diff options
25 files changed, 2519 insertions, 212 deletions
diff --git a/Documentation/devicetree/bindings/tpm/tcg,tpm-tis-i2c.yaml b/Documentation/devicetree/bindings/tpm/tcg,tpm-tis-i2c.yaml index 3ab4434b7352..af7720dc4a12 100644 --- a/Documentation/devicetree/bindings/tpm/tcg,tpm-tis-i2c.yaml +++ b/Documentation/devicetree/bindings/tpm/tcg,tpm-tis-i2c.yaml @@ -32,6 +32,7 @@ properties: - enum: - infineon,slb9673 - nuvoton,npct75x + - st,st33ktpm2xi2c - const: tcg,tpm-tis-i2c - description: TPM 1.2 and 2.0 chips with vendor-specific I²C interface diff --git a/Documentation/security/tpm/index.rst b/Documentation/security/tpm/index.rst index fc40e9f23c85..fa593d960040 100644 --- a/Documentation/security/tpm/index.rst +++ b/Documentation/security/tpm/index.rst @@ -5,6 +5,8 @@ Trusted Platform Module documentation .. toctree:: tpm_event_log + tpm-security + tpm_tis tpm_vtpm_proxy xen-tpmfront tpm_ftpm_tee diff --git a/Documentation/security/tpm/tpm-security.rst b/Documentation/security/tpm/tpm-security.rst new file mode 100644 index 000000000000..4f633f251033 --- /dev/null +++ b/Documentation/security/tpm/tpm-security.rst @@ -0,0 +1,216 @@ +.. SPDX-License-Identifier: GPL-2.0-only + +TPM Security +============ + +The object of this document is to describe how we make the kernel's +use of the TPM reasonably robust in the face of external snooping and +packet alteration attacks (called passive and active interposer attack +in the literature). The current security document is for TPM 2.0. + +Introduction +------------ + +The TPM is usually a discrete chip attached to a PC via some type of +low bandwidth bus. There are exceptions to this such as the Intel +PTT, which is a software TPM running inside a software environment +close to the CPU, which are subject to different attacks, but right at +the moment, most hardened security environments require a discrete +hardware TPM, which is the use case discussed here. + +Snooping and Alteration Attacks against the bus +----------------------------------------------- + +The current state of the art for snooping the `TPM Genie`_ hardware +interposer which is a simple external device that can be installed in +a couple of seconds on any system or laptop. Recently attacks were +successfully demonstrated against the `Windows Bitlocker TPM`_ system. +Most recently the same `attack against TPM based Linux disk +encryption`_ schemes. The next phase of research seems to be hacking +existing devices on the bus to act as interposers, so the fact that +the attacker requires physical access for a few seconds might +evaporate. However, the goal of this document is to protect TPM +secrets and integrity as far as we are able in this environment and to +try to insure that if we can't prevent the attack then at least we can +detect it. + +Unfortunately, most of the TPM functionality, including the hardware +reset capability can be controlled by an attacker who has access to +the bus, so we'll discuss some of the disruption possibilities below. + +Measurement (PCR) Integrity +--------------------------- + +Since the attacker can send their own commands to the TPM, they can +send arbitrary PCR extends and thus disrupt the measurement system, +which would be an annoying denial of service attack. However, there +are two, more serious, classes of attack aimed at entities sealed to +trust measurements. + +1. The attacker could intercept all PCR extends coming from the system + and completely substitute their own values, producing a replay of + an untampered state that would cause PCR measurements to attest to + a trusted state and release secrets + +2. At some point in time the attacker could reset the TPM, clearing + the PCRs and then send down their own measurements which would + effectively overwrite the boot time measurements the TPM has + already done. + +The first can be thwarted by always doing HMAC protection of the PCR +extend and read command meaning measurement values cannot be +substituted without producing a detectable HMAC failure in the +response. However, the second can only really be detected by relying +on some sort of mechanism for protection which would change over TPM +reset. + +Secrets Guarding +---------------- + +Certain information passing in and out of the TPM, such as key sealing +and private key import and random number generation, is vulnerable to +interception which HMAC protection alone cannot protect against, so +for these types of command we must also employ request and response +encryption to prevent the loss of secret information. + +Establishing Initial Trust with the TPM +--------------------------------------- + +In order to provide security from the beginning, an initial shared or +asymmetric secret must be established which must also be unknown to +the attacker. The most obvious avenues for this are the endorsement +and storage seeds, which can be used to derive asymmetric keys. +However, using these keys is difficult because the only way to pass +them into the kernel would be on the command line, which requires +extensive support in the boot system, and there's no guarantee that +either hierarchy would not have some type of authorization. + +The mechanism chosen for the Linux Kernel is to derive the primary +elliptic curve key from the null seed using the standard storage seed +parameters. The null seed has two advantages: firstly the hierarchy +physically cannot have an authorization, so we are always able to use +it and secondly, the null seed changes across TPM resets, meaning if +we establish trust on the null seed at start of day, all sessions +salted with the derived key will fail if the TPM is reset and the seed +changes. + +Obviously using the null seed without any other prior shared secrets, +we have to create and read the initial public key which could, of +course, be intercepted and substituted by the bus interposer. +However, the TPM has a key certification mechanism (using the EK +endorsement certificate, creating an attestation identity key and +certifying the null seed primary with that key) which is too complex +to run within the kernel, so we keep a copy of the null primary key +name, which is what is exported via sysfs so user-space can run the +full certification when it boots. The definitive guarantee here is +that if the null primary key certifies correctly, you know all your +TPM transactions since start of day were secure and if it doesn't, you +know there's an interposer on your system (and that any secret used +during boot may have been leaked). + +Stacking Trust +-------------- + +In the current null primary scenario, the TPM must be completely +cleared before handing it on to the next consumer. However the kernel +hands to user-space the name of the derived null seed key which can +then be verified by certification in user-space. Therefore, this chain +of name handoff can be used between the various boot components as +well (via an unspecified mechanism). For instance, grub could use the +null seed scheme for security and hand the name off to the kernel in +the boot area. The kernel could make its own derivation of the key +and the name and know definitively that if they differ from the handed +off version that tampering has occurred. Thus it becomes possible to +chain arbitrary boot components together (UEFI to grub to kernel) via +the name handoff provided each successive component knows how to +collect the name and verifies it against its derived key. + +Session Properties +------------------ + +All TPM commands the kernel uses allow sessions. HMAC sessions may be +used to check the integrity of requests and responses and decrypt and +encrypt flags may be used to shield parameters and responses. The +HMAC and encryption keys are usually derived from the shared +authorization secret, but for a lot of kernel operations that is well +known (and usually empty). Thus, every HMAC session used by the +kernel must be created using the null primary key as the salt key +which thus provides a cryptographic input into the session key +derivation. Thus, the kernel creates the null primary key once (as a +volatile TPM handle) and keeps it around in a saved context stored in +tpm_chip for every in-kernel use of the TPM. Currently, because of a +lack of de-gapping in the in-kernel resource manager, the session must +be created and destroyed for each operation, but, in future, a single +session may also be reused for the in-kernel HMAC, encryption and +decryption sessions. + +Protection Types +---------------- + +For every in-kernel operation we use null primary salted HMAC to +protect the integrity. Additionally, we use parameter encryption to +protect key sealing and parameter decryption to protect key unsealing +and random number generation. + +Null Primary Key Certification in Userspace +=========================================== + +Every TPM comes shipped with a couple of X.509 certificates for the +primary endorsement key. This document assumes that the Elliptic +Curve version of the certificate exists at 01C00002, but will work +equally well with the RSA certificate (at 01C00001). + +The first step in the certification is primary creation using the +template from the `TCG EK Credential Profile`_ which allows comparison +of the generated primary key against the one in the certificate (the +public key must match). Note that generation of the EK primary +requires the EK hierarchy password, but a pre-generated version of the +EC primary should exist at 81010002 and a TPM2_ReadPublic() may be +performed on this without needing the key authority. Next, the +certificate itself must be verified to chain back to the manufacturer +root (which should be published on the manufacturer website). Once +this is done, an attestation key (AK) is generated within the TPM and +it's name and the EK public key can be used to encrypt a secret using +TPM2_MakeCredential. The TPM then runs TPM2_ActivateCredential which +will only recover the secret if the binding between the TPM, the EK +and the AK is true. the generated AK may now be used to run a +certification of the null primary key whose name the kernel has +exported. Since TPM2_MakeCredential/ActivateCredential are somewhat +complicated, a more simplified process involving an externally +generated private key is described below. + +This process is a simplified abbreviation of the usual privacy CA +based attestation process. The assumption here is that the +attestation is done by the TPM owner who thus has access to only the +owner hierarchy. The owner creates an external public/private key +pair (assume elliptic curve in this case) and wraps the private key +for import using an inner wrapping process and parented to the EC +derived storage primary. The TPM2_Import() is done using a parameter +decryption HMAC session salted to the EK primary (which also does not +require the EK key authority) meaning that the inner wrapping key is +the encrypted parameter and thus the TPM will not be able to perform +the import unless is possesses the certified EK so if the command +succeeds and the HMAC verifies on return we know we have a loadable +copy of the private key only for the certified TPM. This key is now +loaded into the TPM and the Storage primary flushed (to free up space +for the null key generation). + +The null EC primary is now generated using the Storage profile +outlined in the `TCG TPM v2.0 Provisioning Guidance`_; the name of +this key (the hash of the public area) is computed and compared to the +null seed name presented by the kernel in +/sys/class/tpm/tpm0/null_name. If the names do not match, the TPM is +compromised. If the names match, the user performs a TPM2_Certify() +using the null primary as the object handle and the loaded private key +as the sign handle and providing randomized qualifying data. The +signature of the returned certifyInfo is verified against the public +part of the loaded private key and the qualifying data checked to +prevent replay. If all of these tests pass, the user is now assured +that TPM integrity and privacy was preserved across the entire boot +sequence of this kernel. + +.. _TPM Genie: https://www.nccgroup.trust/globalassets/about-us/us/documents/tpm-genie.pdf +.. _Windows Bitlocker TPM: https://dolosgroup.io/blog/2021/7/9/from-stolen-laptop-to-inside-the-company-network +.. _attack against TPM based Linux disk encryption: https://www.secura.com/blog/tpm-sniffing-attacks-against-non-bitlocker-targets +.. _TCG EK Credential Profile: https://trustedcomputinggroup.org/resource/tcg-ek-credential-profile-for-tpm-family-2-0/ +.. _TCG TPM v2.0 Provisioning Guidance: https://trustedcomputinggroup.org/resource/tcg-tpm-v2-0-provisioning-guidance/ diff --git a/Documentation/security/tpm/tpm_tis.rst b/Documentation/security/tpm/tpm_tis.rst new file mode 100644 index 000000000000..b9637f295638 --- /dev/null +++ b/Documentation/security/tpm/tpm_tis.rst @@ -0,0 +1,46 @@ +.. SPDX-License-Identifier: GPL-2.0 + +========================= +TPM FIFO interface driver +========================= + +TCG PTP Specification defines two interface types: FIFO and CRB. The former is +based on sequenced read and write operations, and the latter is based on a +buffer containing the full command or response. + +FIFO (First-In-First-Out) interface is used by the tpm_tis_core dependent +drivers. Originally Linux had only a driver called tpm_tis, which covered +memory mapped (aka MMIO) interface but it was later on extended to cover other +physical interfaces supported by the TCG standard. + +For historical reasons above the original MMIO driver is called tpm_tis and the +framework for FIFO drivers is named as tpm_tis_core. The postfix "tis" in +tpm_tis comes from the TPM Interface Specification, which is the hardware +interface specification for TPM 1.x chips. + +Communication is based on a 20 KiB buffer shared by the TPM chip through a +hardware bus or memory map, depending on the physical wiring. The buffer is +further split into five equal-size 4 KiB buffers, which provide equivalent +sets of registers for communication between the CPU and TPM. These +communication endpoints are called localities in the TCG terminology. + +When the kernel wants to send commands to the TPM chip, it first reserves +locality 0 by setting the requestUse bit in the TPM_ACCESS register. The bit is +cleared by the chip when the access is granted. Once it completes its +communication, the kernel writes the TPM_ACCESS.activeLocality bit. This +informs the chip that the locality has been relinquished. + +Pending localities are served in order by the chip in descending order, one at +a time: + +- Locality 0 has the lowest priority. +- Locality 5 has the highest priority. + +Further information on the purpose and meaning of the localities can be found +in section 3.2 of the TCG PC Client Platform TPM Profile Specification. + +References +========== + +TCG PC Client Platform TPM Profile (PTP) Specification +https://trustedcomputinggroup.org/resource/pc-client-platform-tpm-profile-ptp-specification/ diff --git a/drivers/char/tpm/Kconfig b/drivers/char/tpm/Kconfig index 927088b2c3d3..e63a6a17793c 100644 --- a/drivers/char/tpm/Kconfig +++ b/drivers/char/tpm/Kconfig @@ -27,6 +27,20 @@ menuconfig TCG_TPM if TCG_TPM +config TCG_TPM2_HMAC + bool "Use HMAC and encrypted transactions on the TPM bus" + default y + select CRYPTO_ECDH + select CRYPTO_LIB_AESCFB + select CRYPTO_LIB_SHA256 + help + Setting this causes us to deploy a scheme which uses request + and response HMACs in addition to encryption for + communicating with the TPM to prevent or detect bus snooping + and interposer attacks (see tpm-security.rst). Saying Y + here adds some encryption overhead to all kernel to TPM + transactions. + config HW_RANDOM_TPM bool "TPM HW Random Number Generator support" depends on TCG_TPM && HW_RANDOM && !(TCG_TPM=y && HW_RANDOM=m) @@ -149,6 +163,7 @@ config TCG_NSC config TCG_ATMEL tristate "Atmel TPM Interface" depends on PPC64 || HAS_IOPORT_MAP + depends on HAS_IOPORT help If you have a TPM security chip from Atmel say Yes and it will be accessible from within Linux. To compile this driver @@ -156,7 +171,7 @@ config TCG_ATMEL config TCG_INFINEON tristate "Infineon Technologies TPM Interface" - depends on PNP + depends on PNP || COMPILE_TEST help If you have a TPM security chip from Infineon Technologies (either SLD 9630 TT 1.1 or SLB 9635 TT 1.2) say Yes and it diff --git a/drivers/char/tpm/Makefile b/drivers/char/tpm/Makefile index 0222b1ddb310..4c695b0388f3 100644 --- a/drivers/char/tpm/Makefile +++ b/drivers/char/tpm/Makefile @@ -15,7 +15,9 @@ tpm-y += tpm-sysfs.o tpm-y += eventlog/common.o tpm-y += eventlog/tpm1.o tpm-y += eventlog/tpm2.o +tpm-y += tpm-buf.o +tpm-$(CONFIG_TCG_TPM2_HMAC) += tpm2-sessions.o tpm-$(CONFIG_ACPI) += tpm_ppi.o eventlog/acpi.o tpm-$(CONFIG_EFI) += eventlog/efi.o tpm-$(CONFIG_OF) += eventlog/of.o diff --git a/drivers/char/tpm/eventlog/acpi.c b/drivers/char/tpm/eventlog/acpi.c index bd757d836c5c..69533d0bfb51 100644 --- a/drivers/char/tpm/eventlog/acpi.c +++ b/drivers/char/tpm/eventlog/acpi.c @@ -142,7 +142,6 @@ int tpm_read_log_acpi(struct tpm_chip *chip) log->bios_event_log_end = log->bios_event_log + len; - ret = -EIO; virt = acpi_os_map_iomem(start, len); if (!virt) { dev_warn(&chip->dev, "%s: Failed to map ACPI memory\n", __func__); diff --git a/drivers/char/tpm/tpm-buf.c b/drivers/char/tpm/tpm-buf.c new file mode 100644 index 000000000000..647c6ca92ac3 --- /dev/null +++ b/drivers/char/tpm/tpm-buf.c @@ -0,0 +1,252 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Handling of TPM command and other buffers. + */ + +#include <linux/tpm_command.h> +#include <linux/module.h> +#include <linux/tpm.h> + +/** + * tpm_buf_init() - Allocate and initialize a TPM command + * @buf: A &tpm_buf + * @tag: TPM_TAG_RQU_COMMAND, TPM2_ST_NO_SESSIONS or TPM2_ST_SESSIONS + * @ordinal: A command ordinal + * + * Return: 0 or -ENOMEM + */ +int tpm_buf_init(struct tpm_buf *buf, u16 tag, u32 ordinal) +{ + buf->data = (u8 *)__get_free_page(GFP_KERNEL); + if (!buf->data) + return -ENOMEM; + + tpm_buf_reset(buf, tag, ordinal); + return 0; +} +EXPORT_SYMBOL_GPL(tpm_buf_init); + +/** + * tpm_buf_reset() - Initialize a TPM command + * @buf: A &tpm_buf + * @tag: TPM_TAG_RQU_COMMAND, TPM2_ST_NO_SESSIONS or TPM2_ST_SESSIONS + * @ordinal: A command ordinal + */ +void tpm_buf_reset(struct tpm_buf *buf, u16 tag, u32 ordinal) +{ + struct tpm_header *head = (struct tpm_header *)buf->data; + + WARN_ON(tag != TPM_TAG_RQU_COMMAND && tag != TPM2_ST_NO_SESSIONS && + tag != TPM2_ST_SESSIONS && tag != 0); + + buf->flags = 0; + buf->length = sizeof(*head); + head->tag = cpu_to_be16(tag); + head->length = cpu_to_be32(sizeof(*head)); + head->ordinal = cpu_to_be32(ordinal); + buf->handles = 0; +} +EXPORT_SYMBOL_GPL(tpm_buf_reset); + +/** + * tpm_buf_init_sized() - Allocate and initialize a sized (TPM2B) buffer + * @buf: A @tpm_buf + * + * Return: 0 or -ENOMEM + */ +int tpm_buf_init_sized(struct tpm_buf *buf) +{ + buf->data = (u8 *)__get_free_page(GFP_KERNEL); + if (!buf->data) + return -ENOMEM; + + tpm_buf_reset_sized(buf); + return 0; +} +EXPORT_SYMBOL_GPL(tpm_buf_init_sized); + +/** + * tpm_buf_reset_sized() - Initialize a sized buffer + * @buf: A &tpm_buf + */ +void tpm_buf_reset_sized(struct tpm_buf *buf) +{ + buf->flags = TPM_BUF_TPM2B; + buf->length = 2; + buf->data[0] = 0; + buf->data[1] = 0; +} +EXPORT_SYMBOL_GPL(tpm_buf_reset_sized); + +void tpm_buf_destroy(struct tpm_buf *buf) +{ + free_page((unsigned long)buf->data); +} +EXPORT_SYMBOL_GPL(tpm_buf_destroy); + +/** + * tpm_buf_length() - Return the number of bytes consumed by the data + * @buf: A &tpm_buf + * + * Return: The number of bytes consumed by the buffer + */ +u32 tpm_buf_length(struct tpm_buf *buf) +{ + return buf->length; +} +EXPORT_SYMBOL_GPL(tpm_buf_length); + +/** + * tpm_buf_append() - Append data to an initialized buffer + * @buf: A &tpm_buf + * @new_data: A data blob + * @new_length: Size of the appended data + */ +void tpm_buf_append(struct tpm_buf *buf, const u8 *new_data, u16 new_length) +{ + /* Return silently if overflow has already happened. */ + if (buf->flags & TPM_BUF_OVERFLOW) + return; + + if ((buf->length + new_length) > PAGE_SIZE) { + WARN(1, "tpm_buf: write overflow\n"); + buf->flags |= TPM_BUF_OVERFLOW; + return; + } + + memcpy(&buf->data[buf->length], new_data, new_length); + buf->length += new_length; + + if (buf->flags & TPM_BUF_TPM2B) + ((__be16 *)buf->data)[0] = cpu_to_be16(buf->length - 2); + else + ((struct tpm_header *)buf->data)->length = cpu_to_be32(buf->length); +} +EXPORT_SYMBOL_GPL(tpm_buf_append); + +void tpm_buf_append_u8(struct tpm_buf *buf, const u8 value) +{ + tpm_buf_append(buf, &value, 1); +} +EXPORT_SYMBOL_GPL(tpm_buf_append_u8); + +void tpm_buf_append_u16(struct tpm_buf *buf, const u16 value) +{ + __be16 value2 = cpu_to_be16(value); + + tpm_buf_append(buf, (u8 *)&value2, 2); +} +EXPORT_SYMBOL_GPL(tpm_buf_append_u16); + +void tpm_buf_append_u32(struct tpm_buf *buf, const u32 value) +{ + __be32 value2 = cpu_to_be32(value); + + tpm_buf_append(buf, (u8 *)&value2, 4); +} +EXPORT_SYMBOL_GPL(tpm_buf_append_u32); + +/** + * tpm_buf_read() - Read from a TPM buffer + * @buf: &tpm_buf instance + * @offset: offset within the buffer + * @count: the number of bytes to read + * @output: the output buffer + */ +static void tpm_buf_read(struct tpm_buf *buf, off_t *offset, size_t count, void *output) +{ + off_t next_offset; + + /* Return silently if overflow has already happened. */ + if (buf->flags & TPM_BUF_BOUNDARY_ERROR) + return; + + next_offset = *offset + count; + if (next_offset > buf->length) { + WARN(1, "tpm_buf: read out of boundary\n"); + buf->flags |= TPM_BUF_BOUNDARY_ERROR; + return; + } + + memcpy(output, &buf->data[*offset], count); + *offset = next_offset; +} + +/** + * tpm_buf_read_u8() - Read 8-bit word from a TPM buffer + * @buf: &tpm_buf instance + * @offset: offset within the buffer + * + * Return: next 8-bit word + */ +u8 tpm_buf_read_u8(struct tpm_buf *buf, off_t *offset) +{ + u8 value; + + tpm_buf_read(buf, offset, sizeof(value), &value); + + return value; +} +EXPORT_SYMBOL_GPL(tpm_buf_read_u8); + +/** + * tpm_buf_read_u16() - Read 16-bit word from a TPM buffer + * @buf: &tpm_buf instance + * @offset: offset within the buffer + * + * Return: next 16-bit word + */ +u16 tpm_buf_read_u16(struct tpm_buf *buf, off_t *offset) +{ + u16 value; + + tpm_buf_read(buf, offset, sizeof(value), &value); + + return be16_to_cpu(value); +} +EXPORT_SYMBOL_GPL(tpm_buf_read_u16); + +/** + * tpm_buf_read_u32() - Read 32-bit word from a TPM buffer + * @buf: &tpm_buf instance + * @offset: offset within the buffer + * + * Return: next 32-bit word + */ +u32 tpm_buf_read_u32(struct tpm_buf *buf, off_t *offset) +{ + u32 value; + + tpm_buf_read(buf, offset, sizeof(value), &value); + + return be32_to_cpu(value); +} +EXPORT_SYMBOL_GPL(tpm_buf_read_u32); + +static u16 tpm_buf_tag(struct tpm_buf *buf) +{ + struct tpm_header *head = (struct tpm_header *)buf->data; + + return be16_to_cpu(head->tag); +} + +/** + * tpm_buf_parameters - return the TPM response parameters area of the tpm_buf + * @buf: tpm_buf to use + * + * Where the parameters are located depends on the tag of a TPM + * command (it's immediately after the header for TPM_ST_NO_SESSIONS + * or 4 bytes after for TPM_ST_SESSIONS). Evaluate this and return a + * pointer to the first byte of the parameters area. + * + * @return: pointer to parameters area + */ +u8 *tpm_buf_parameters(struct tpm_buf *buf) +{ + int offset = TPM_HEADER_SIZE; + + if (tpm_buf_tag(buf) == TPM2_ST_SESSIONS) + offset += 4; + + return &buf->data[offset]; +} diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c index 42b1062e33cd..854546000c92 100644 --- a/drivers/char/tpm/tpm-chip.c +++ b/drivers/char/tpm/tpm-chip.c @@ -158,6 +158,9 @@ int tpm_try_get_ops(struct tpm_chip *chip) { int rc = -EIO; + if (chip->flags & TPM_CHIP_FLAG_DISABLE) + return rc; + get_device(&chip->dev); down_read(&chip->ops_sem); @@ -275,6 +278,9 @@ static void tpm_dev_release(struct device *dev) kfree(chip->work_space.context_buf); kfree(chip->work_space.session_buf); kfree(chip->allocated_banks); +#ifdef CONFIG_TCG_TPM2_HMAC + kfree(chip->auth); +#endif kfree(chip); } diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c index 757336324c90..5da134f12c9a 100644 --- a/drivers/char/tpm/tpm-interface.c +++ b/drivers/char/tpm/tpm-interface.c @@ -232,6 +232,7 @@ ssize_t tpm_transmit_cmd(struct tpm_chip *chip, struct tpm_buf *buf, if (len < min_rsp_body_length + TPM_HEADER_SIZE) return -EFAULT; + buf->length = len; return 0; } EXPORT_SYMBOL_GPL(tpm_transmit_cmd); @@ -342,31 +343,6 @@ out: } EXPORT_SYMBOL_GPL(tpm_pcr_extend); -/** - * tpm_send - send a TPM command - * @chip: a &struct tpm_chip instance, %NULL for the default chip - * @cmd: a TPM command buffer - * @buflen: the length of the TPM command buffer - * - * Return: same as with tpm_transmit_cmd() - */ -int tpm_send(struct tpm_chip *chip, void *cmd, size_t buflen) -{ - struct tpm_buf buf; - int rc; - - chip = tpm_find_get_ops(chip); - if (!chip) - return -ENODEV; - - buf.data = cmd; - rc = tpm_transmit_cmd(chip, &buf, 0, "attempting to a send a command"); - - tpm_put_ops(chip); - return rc; -} -EXPORT_SYMBOL_GPL(tpm_send); - int tpm_auto_startup(struct tpm_chip *chip) { int rc; diff --git a/drivers/char/tpm/tpm-sysfs.c b/drivers/char/tpm/tpm-sysfs.c index 54c71473aa29..94231f052ea7 100644 --- a/drivers/char/tpm/tpm-sysfs.c +++ b/drivers/char/tpm/tpm-sysfs.c @@ -309,6 +309,21 @@ static ssize_t tpm_version_major_show(struct device *dev, } static DEVICE_ATTR_RO(tpm_version_major); +#ifdef CONFIG_TCG_TPM2_HMAC +static ssize_t null_name_show(struct device *dev, struct device_attribute *attr, + char *buf) +{ + struct tpm_chip *chip = to_tpm_chip(dev); + int size = TPM2_NAME_SIZE; + + bin2hex(buf, chip->null_key_name, size); + size *= 2; + buf[size++] = '\n'; + return size; +} +static DEVICE_ATTR_RO(null_name); +#endif + static struct attribute *tpm1_dev_attrs[] = { &dev_attr_pubek.attr, &dev_attr_pcrs.attr, @@ -326,6 +341,9 @@ static struct attribute *tpm1_dev_attrs[] = { static struct attribute *tpm2_dev_attrs[] = { &dev_attr_tpm_version_major.attr, +#ifdef CONFIG_TCG_TPM2_HMAC + &dev_attr_null_name.attr, +#endif NULL }; diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h index 61445f1dc46d..6b8b9956ba69 100644 --- a/drivers/char/tpm/tpm.h +++ b/drivers/char/tpm/tpm.h @@ -312,9 +312,23 @@ int tpm2_commit_space(struct tpm_chip *chip, struct tpm_space *space, void *buf, size_t *bufsiz); int tpm_devs_add(struct tpm_chip *chip); void tpm_devs_remove(struct tpm_chip *chip); +int tpm2_save_context(struct tpm_chip *chip, u32 handle, u8 *buf, + unsigned int buf_size, unsigned int *offset); +int tpm2_load_context(struct tpm_chip *chip, u8 *buf, + unsigned int *offset, u32 *handle); void tpm_bios_log_setup(struct tpm_chip *chip); void tpm_bios_log_teardown(struct tpm_chip *chip); int tpm_dev_common_init(void); void tpm_dev_common_exit(void); + +#ifdef CONFIG_TCG_TPM2_HMAC +int tpm2_sessions_init(struct tpm_chip *chip); +#else +static inline int tpm2_sessions_init(struct tpm_chip *chip) +{ + return 0; +} +#endif + #endif diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c index 93545be190a5..0cdf892ec2a7 100644 --- a/drivers/char/tpm/tpm2-cmd.c +++ b/drivers/char/tpm/tpm2-cmd.c @@ -216,13 +216,6 @@ out: return rc; } -struct tpm2_null_auth_area { - __be32 handle; - __be16 nonce_size; - u8 attributes; - __be16 auth_size; -} __packed; - /** * tpm2_pcr_extend() - extend a PCR value * @@ -236,24 +229,22 @@ int tpm2_pcr_extend(struct tpm_chip *chip, u32 pcr_idx, struct tpm_digest *digests) { struct tpm_buf buf; - struct tpm2_null_auth_area auth_area; int rc; int i; - rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_PCR_EXTEND); + rc = tpm2_start_auth_session(chip); if (rc) return rc; - tpm_buf_append_u32(&buf, pcr_idx); + rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_PCR_EXTEND); + if (rc) { + tpm2_end_auth_session(chip); + return rc; + } - auth_area.handle = cpu_to_be32(TPM2_RS_PW); - auth_area.nonce_size = 0; - auth_area.attributes = 0; - auth_area.auth_size = 0; + tpm_buf_append_name(chip, &buf, pcr_idx, NULL); + tpm_buf_append_hmac_session(chip, &buf, 0, NULL, 0); - tpm_buf_append_u32(&buf, sizeof(struct tpm2_null_auth_area)); - tpm_buf_append(&buf, (const unsigned char *)&auth_area, - sizeof(auth_area)); tpm_buf_append_u32(&buf, chip->nr_allocated_banks); for (i = 0; i < chip->nr_allocated_banks; i++) { @@ -262,7 +253,9 @@ int tpm2_pcr_extend(struct tpm_chip *chip, u32 pcr_idx, chip->allocated_banks[i].digest_size); } + tpm_buf_fill_hmac_session(chip, &buf); rc = tpm_transmit_cmd(chip, &buf, 0, "attempting extend a PCR value"); + rc = tpm_buf_check_hmac_response(chip, &buf, rc); tpm_buf_destroy(&buf); @@ -299,25 +292,35 @@ int tpm2_get_random(struct tpm_chip *chip, u8 *dest, size_t max) if (!num_bytes || max > TPM_MAX_RNG_DATA) return -EINVAL; - err = tpm_buf_init(&buf, 0, 0); + err = tpm2_start_auth_session(chip); if (err) return err; + err = tpm_buf_init(&buf, 0, 0); + if (err) { + tpm2_end_auth_session(chip); + return err; + } + do { - tpm_buf_reset(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_GET_RANDOM); + tpm_buf_reset(&buf, TPM2_ST_SESSIONS, TPM2_CC_GET_RANDOM); + tpm_buf_append_hmac_session_opt(chip, &buf, TPM2_SA_ENCRYPT + | TPM2_SA_CONTINUE_SESSION, + NULL, 0); tpm_buf_append_u16(&buf, num_bytes); + tpm_buf_fill_hmac_session(chip, &buf); err = tpm_transmit_cmd(chip, &buf, offsetof(struct tpm2_get_random_out, buffer), "attempting get random"); + err = tpm_buf_check_hmac_response(chip, &buf, err); if (err) { if (err > 0) err = -EIO; goto out; } - out = (struct tpm2_get_random_out *) - &buf.data[TPM_HEADER_SIZE]; + out = (struct tpm2_get_random_out *)tpm_buf_parameters(&buf); recd = min_t(u32, be16_to_cpu(out->size), num_bytes); if (tpm_buf_length(&buf) < TPM_HEADER_SIZE + @@ -334,9 +337,12 @@ int tpm2_get_random(struct tpm_chip *chip, u8 *dest, size_t max) } while (retries-- && total < max); tpm_buf_destroy(&buf); + tpm2_end_auth_session(chip); + return total ? total : -EIO; out: tpm_buf_destroy(&buf); + tpm2_end_auth_session(chip); return err; } @@ -759,6 +765,11 @@ int tpm2_auto_startup(struct tpm_chip *chip) rc = 0; } + if (rc) + goto out; + + rc = tpm2_sessions_init(chip); + out: /* * Infineon TPM in field upgrade mode will return no data for the number diff --git a/drivers/char/tpm/tpm2-sessions.c b/drivers/char/tpm/tpm2-sessions.c new file mode 100644 index 000000000000..ea8860661876 --- /dev/null +++ b/drivers/char/tpm/tpm2-sessions.c @@ -0,0 +1,1286 @@ +// SPDX-License-Identifier: GPL-2.0 + +/* + * Copyright (C) 2018 James.Bottomley@HansenPartnership.com + * + * Cryptographic helper routines for handling TPM2 sessions for + * authorization HMAC and request response encryption. + * + * The idea is to ensure that every TPM command is HMAC protected by a + * session, meaning in-flight tampering would be detected and in + * addition all sensitive inputs and responses should be encrypted. + * + * The basic way this works is to use a TPM feature called salted + * sessions where a random secret used in session construction is + * encrypted to the public part of a known TPM key. The problem is we + * have no known keys, so initially a primary Elliptic Curve key is + * derived from the NULL seed (we use EC because most TPMs generate + * these keys much faster than RSA ones). The curve used is NIST_P256 + * because that's now mandated to be present in 'TCG TPM v2.0 + * Provisioning Guidance' + * + * Threat problems: the initial TPM2_CreatePrimary is not (and cannot + * be) session protected, so a clever Man in the Middle could return a + * public key they control to this command and from there intercept + * and decode all subsequent session based transactions. The kernel + * cannot mitigate this threat but, after boot, userspace can get + * proof this has not happened by asking the TPM to certify the NULL + * key. This certification would chain back to the TPM Endorsement + * Certificate and prove the NULL seed primary had not been tampered + * with and thus all sessions must have been cryptographically secure. + * To assist with this, the initial NULL seed public key name is made + * available in a sysfs file. + * + * Use of these functions: + * + * The design is all the crypto, hash and hmac gunk is confined in this + * file and never needs to be seen even by the kernel internal user. To + * the user there's an init function tpm2_sessions_init() that needs to + * be called once per TPM which generates the NULL seed primary key. + * + * These are the usage functions: + * + * tpm2_start_auth_session() which allocates the opaque auth structure + * and gets a session from the TPM. This must be called before + * any of the following functions. The session is protected by a + * session_key which is derived from a random salt value + * encrypted to the NULL seed. + * tpm2_end_auth_session() kills the session and frees the resources. + * Under normal operation this function is done by + * tpm_buf_check_hmac_response(), so this is only to be used on + * error legs where the latter is not executed. + * tpm_buf_append_name() to add a handle to the buffer. This must be + * used in place of the usual tpm_buf_append_u32() for adding + * handles because handles have to be processed specially when + * calculating the HMAC. In particular, for NV, volatile and + * permanent objects you now need to provide the name. + * tpm_buf_append_hmac_session() which appends the hmac session to the + * buf in the same way tpm_buf_append_auth does(). + * tpm_buf_fill_hmac_session() This calculates the correct hash and + * places it in the buffer. It must be called after the complete + * command buffer is finalized so it can fill in the correct HMAC + * based on the parameters. + * tpm_buf_check_hmac_response() which checks the session response in + * the buffer and calculates what it should be. If there's a + * mismatch it will log a warning and return an error. If + * tpm_buf_append_hmac_session() did not specify + * TPM_SA_CONTINUE_SESSION then the session will be closed (if it + * hasn't been consumed) and the auth structure freed. + */ + +#include "tpm.h" +#include <linux/random.h> +#include <linux/scatterlist.h> +#include <asm/unaligned.h> +#include <crypto/kpp.h> +#include <crypto/ecdh.h> +#include <crypto/hash.h> +#include <crypto/hmac.h> + +/* maximum number of names the TPM must remember for authorization */ +#define AUTH_MAX_NAMES 3 + +static int tpm2_create_primary(struct tpm_chip *chip, u32 hierarchy, + u32 *handle, u8 *name); + +/* + * This is the structure that carries all the auth information (like + * session handle, nonces, session key and auth) from use to use it is + * designed to be opaque to anything outside. + */ +struct tpm2_auth { + u32 handle; + /* + * This has two meanings: before tpm_buf_fill_hmac_session() + * it marks the offset in the buffer of the start of the + * sessions (i.e. after all the handles). Once the buffer has + * been filled it markes the session number of our auth + * session so we can find it again in the response buffer. + * + * The two cases are distinguished because the first offset + * must always be greater than TPM_HEADER_SIZE and the second + * must be less than or equal to 5. + */ + u32 session; + /* + * the size here is variable and set by the size of our_nonce + * which must be between 16 and the name hash length. we set + * the maximum sha256 size for the greatest protection + */ + u8 our_nonce[SHA256_DIGEST_SIZE]; + u8 tpm_nonce[SHA256_DIGEST_SIZE]; + /* + * the salt is only used across the session command/response + * after that it can be used as a scratch area + */ + union { + u8 salt[EC_PT_SZ]; + /* scratch for key + IV */ + u8 scratch[AES_KEY_BYTES + AES_BLOCK_SIZE]; + }; + /* + * the session key and passphrase are the same size as the + * name digest (sha256 again). The session key is constant + * for the use of the session and the passphrase can change + * with every invocation. + * + * Note: these fields must be adjacent and in this order + * because several HMAC/KDF schemes use the combination of the + * session_key and passphrase. + */ + u8 session_key[SHA256_DIGEST_SIZE]; + u8 passphrase[SHA256_DIGEST_SIZE]; + int passphrase_len; + struct crypto_aes_ctx aes_ctx; + /* saved session attributes: */ + u8 attrs; + __be32 ordinal; + + /* + * memory for three authorization handles. We know them by + * handle, but they are part of the session by name, which + * we must compute and remember + */ + u32 name_h[AUTH_MAX_NAMES]; + u8 name[AUTH_MAX_NAMES][2 + SHA512_DIGEST_SIZE]; +}; + +/* + * Name Size based on TPM algorithm (assumes no hash bigger than 255) + */ +static u8 name_size(const u8 *name) +{ + static u8 size_map[] = { + [TPM_ALG_SHA1] = SHA1_DIGEST_SIZE, + [TPM_ALG_SHA256] = SHA256_DIGEST_SIZE, + [TPM_ALG_SHA384] = SHA384_DIGEST_SIZE, + [TPM_ALG_SHA512] = SHA512_DIGEST_SIZE, + }; + u16 alg = get_unaligned_be16(name); + return size_map[alg] + 2; +} + +/* + * It turns out the crypto hmac(sha256) is hard for us to consume + * because it assumes a fixed key and the TPM seems to change the key + * on every operation, so we weld the hmac init and final functions in + * here to give it the same usage characteristics as a regular hash + */ +static void tpm2_hmac_init(struct sha256_state *sctx, u8 *key, u32 key_len) +{ + u8 pad[SHA256_BLOCK_SIZE]; + int i; + + sha256_init(sctx); + for (i = 0; i < sizeof(pad); i++) { + if (i < key_len) + pad[i] = key[i]; + else + pad[i] = 0; + pad[i] ^= HMAC_IPAD_VALUE; + } + sha256_update(sctx, pad, sizeof(pad)); +} + +static void tpm2_hmac_final(struct sha256_state *sctx, u8 *key, u32 key_len, + u8 *out) +{ + u8 pad[SHA256_BLOCK_SIZE]; + int i; + + for (i = 0; i < sizeof(pad); i++) { + if (i < key_len) + pad[i] = key[i]; + else + pad[i] = 0; + pad[i] ^= HMAC_OPAD_VALUE; + } + + /* collect the final hash; use out as temporary storage */ + sha256_final(sctx, out); + + sha256_init(sctx); + sha256_update(sctx, pad, sizeof(pad)); + sha256_update(sctx, out, SHA256_DIGEST_SIZE); + sha256_final(sctx, out); +} + +/* + * assume hash sha256 and nonces u, v of size SHA256_DIGEST_SIZE but + * otherwise standard tpm2_KDFa. Note output is in bytes not bits. + */ +static void tpm2_KDFa(u8 *key, u32 key_len, const char *label, u8 *u, + u8 *v, u32 bytes, u8 *out) +{ + u32 counter = 1; + const __be32 bits = cpu_to_be32(bytes * 8); + + while (bytes > 0) { + struct sha256_state sctx; + __be32 c = cpu_to_be32(counter); + + tpm2_hmac_init(&sctx, key, key_len); + sha256_update(&sctx, (u8 *)&c, sizeof(c)); + sha256_update(&sctx, label, strlen(label)+1); + sha256_update(&sctx, u, SHA256_DIGEST_SIZE); + sha256_update(&sctx, v, SHA256_DIGEST_SIZE); + sha256_update(&sctx, (u8 *)&bits, sizeof(bits)); + tpm2_hmac_final(&sctx, key, key_len, out); + + bytes -= SHA256_DIGEST_SIZE; + counter++; + out += SHA256_DIGEST_SIZE; + } +} + +/* + * Somewhat of a bastardization of the real KDFe. We're assuming + * we're working with known point sizes for the input parameters and + * the hash algorithm is fixed at sha256. Because we know that the + * point size is 32 bytes like the hash size, there's no need to loop + * in this KDF. + */ +static void tpm2_KDFe(u8 z[EC_PT_SZ], const char *str, u8 *pt_u, u8 *pt_v, + u8 *out) +{ + struct sha256_state sctx; + /* + * this should be an iterative counter, but because we know + * we're only taking 32 bytes for the point using a sha256 + * hash which is also 32 bytes, there's only one loop + */ + __be32 c = cpu_to_be32(1); + + sha256_init(&sctx); + /* counter (BE) */ + sha256_update(&sctx, (u8 *)&c, sizeof(c)); + /* secret value */ + sha256_update(&sctx, z, EC_PT_SZ); + /* string including trailing zero */ + sha256_update(&sctx, str, strlen(str)+1); + sha256_update(&sctx, pt_u, EC_PT_SZ); + sha256_update(&sctx, pt_v, EC_PT_SZ); + sha256_final(&sctx, out); +} + +static void tpm_buf_append_salt(struct tpm_buf *buf, struct tpm_chip *chip) +{ + struct crypto_kpp *kpp; + struct kpp_request *req; + struct scatterlist s[2], d[1]; + struct ecdh p = {0}; + u8 encoded_key[EC_PT_SZ], *x, *y; + unsigned int buf_len; + + /* secret is two sized points */ + tpm_buf_append_u16(buf, (EC_PT_SZ + 2)*2); + /* + * we cheat here and append uninitialized data to form + * the points. All we care about is getting the two + * co-ordinate pointers, which will be used to overwrite + * the uninitialized data + */ + tpm_buf_append_u16(buf, EC_PT_SZ); + x = &buf->data[tpm_buf_length(buf)]; + tpm_buf_append(buf, encoded_key, EC_PT_SZ); + tpm_buf_append_u16(buf, EC_PT_SZ); + y = &buf->data[tpm_buf_length(buf)]; + tpm_buf_append(buf, encoded_key, EC_PT_SZ); + sg_init_table(s, 2); + sg_set_buf(&s[0], x, EC_PT_SZ); + sg_set_buf(&s[1], y, EC_PT_SZ); + + kpp = crypto_alloc_kpp("ecdh-nist-p256", CRYPTO_ALG_INTERNAL, 0); + if (IS_ERR(kpp)) { + dev_err(&chip->dev, "crypto ecdh allocation failed\n"); + return; + } + + buf_len = crypto_ecdh_key_len(&p); + if (sizeof(encoded_key) < buf_len) { + dev_err(&chip->dev, "salt buffer too small needs %d\n", + buf_len); + goto out; + } + crypto_ecdh_encode_key(encoded_key, buf_len, &p); + /* this generates a random private key */ + crypto_kpp_set_secret(kpp, encoded_key, buf_len); + + /* salt is now the public point of this private key */ + req = kpp_request_alloc(kpp, GFP_KERNEL); + if (!req) + goto out; + kpp_request_set_input(req, NULL, 0); + kpp_request_set_output(req, s, EC_PT_SZ*2); + crypto_kpp_generate_public_key(req); + /* + * we're not done: now we have to compute the shared secret + * which is our private key multiplied by the tpm_key public + * point, we actually only take the x point and discard the y + * point and feed it through KDFe to get the final secret salt + */ + sg_set_buf(&s[0], chip->null_ec_key_x, EC_PT_SZ); + sg_set_buf(&s[1], chip->null_ec_key_y, EC_PT_SZ); + kpp_request_set_input(req, s, EC_PT_SZ*2); + sg_init_one(d, chip->auth->salt, EC_PT_SZ); + kpp_request_set_output(req, d, EC_PT_SZ); + crypto_kpp_compute_shared_secret(req); + kpp_request_free(req); + + /* + * pass the shared secret through KDFe for salt. Note salt + * area is used both for input shared secret and output salt. + * This works because KDFe fully consumes the secret before it + * writes the salt + */ + tpm2_KDFe(chip->auth->salt, "SECRET", x, chip->null_ec_key_x, + chip->auth->salt); + + out: + crypto_free_kpp(kpp); +} + +/** + * tpm_buf_append_hmac_session() - Append a TPM session element + * @chip: the TPM chip structure + * @buf: The buffer to be appended + * @attributes: The session attributes + * @passphrase: The session authority (NULL if none) + * @passphrase_len: The length of the session authority (0 if none) + * + * This fills in a session structure in the TPM command buffer, except + * for the HMAC which cannot be computed until the command buffer is + * complete. The type of session is controlled by the @attributes, + * the main ones of which are TPM2_SA_CONTINUE_SESSION which means the + * session won't terminate after tpm_buf_check_hmac_response(), + * TPM2_SA_DECRYPT which means this buffers first parameter should be + * encrypted with a session key and TPM2_SA_ENCRYPT, which means the + * response buffer's first parameter needs to be decrypted (confusing, + * but the defines are written from the point of view of the TPM). + * + * Any session appended by this command must be finalized by calling + * tpm_buf_fill_hmac_session() otherwise the HMAC will be incorrect + * and the TPM will reject the command. + * + * As with most tpm_buf operations, success is assumed because failure + * will be caused by an incorrect programming model and indicated by a + * kernel message. + */ +void tpm_buf_append_hmac_session(struct tpm_chip *chip, struct tpm_buf *buf, + u8 attributes, u8 *passphrase, + int passphrase_len) +{ + u8 nonce[SHA256_DIGEST_SIZE]; + u32 len; + struct tpm2_auth *auth = chip->auth; + + /* + * The Architecture Guide requires us to strip trailing zeros + * before computing the HMAC + */ + while (passphrase && passphrase_len > 0 + && passphrase[passphrase_len - 1] == '\0') + passphrase_len--; + + auth->attrs = attributes; + auth->passphrase_len = passphrase_len; + if (passphrase_len) + memcpy(auth->passphrase, passphrase, passphrase_len); + + if (auth->session != tpm_buf_length(buf)) { + /* we're not the first session */ + len = get_unaligned_be32(&buf->data[auth->session]); + if (4 + len + auth->session != tpm_buf_length(buf)) { + WARN(1, "session length mismatch, cannot append"); + return; + } + + /* add our new session */ + len += 9 + 2 * SHA256_DIGEST_SIZE; + put_unaligned_be32(len, &buf->data[auth->session]); + } else { + tpm_buf_append_u32(buf, 9 + 2 * SHA256_DIGEST_SIZE); + } + + /* random number for our nonce */ + get_random_bytes(nonce, sizeof(nonce)); + memcpy(auth->our_nonce, nonce, sizeof(nonce)); + tpm_buf_append_u32(buf, auth->handle); + /* our new nonce */ + tpm_buf_append_u16(buf, SHA256_DIGEST_SIZE); + tpm_buf_append(buf, nonce, SHA256_DIGEST_SIZE); + tpm_buf_append_u8(buf, auth->attrs); + /* and put a placeholder for the hmac */ + tpm_buf_append_u16(buf, SHA256_DIGEST_SIZE); + tpm_buf_append(buf, nonce, SHA256_DIGEST_SIZE); +} +EXPORT_SYMBOL(tpm_buf_append_hmac_session); + +/** + * tpm_buf_fill_hmac_session() - finalize the session HMAC + * @chip: the TPM chip structure + * @buf: The buffer to be appended + * + * This command must not be called until all of the parameters have + * been appended to @buf otherwise the computed HMAC will be + * incorrect. + * + * This function computes and fills in the session HMAC using the + * session key and, if TPM2_SA_DECRYPT was specified, computes the + * encryption key and encrypts the first parameter of the command + * buffer with it. + * + * As with most tpm_buf operations, success is assumed because failure + * will be caused by an incorrect programming model and indicated by a + * kernel message. + */ +void tpm_buf_fill_hmac_session(struct tpm_chip *chip, struct tpm_buf *buf) +{ + u32 cc, handles, val; + struct tpm2_auth *auth = chip->auth; + int i; + struct tpm_header *head = (struct tpm_header *)buf->data; + off_t offset_s = TPM_HEADER_SIZE, offset_p; + u8 *hmac = NULL; + u32 attrs; + u8 cphash[SHA256_DIGEST_SIZE]; + struct sha256_state sctx; + + /* save the command code in BE format */ + auth->ordinal = head->ordinal; + + cc = be32_to_cpu(head->ordinal); + + i = tpm2_find_cc(chip, cc); + if (i < 0) { + dev_err(&chip->dev, "Command 0x%x not found in TPM\n", cc); + return; + } + attrs = chip->cc_attrs_tbl[i]; + + handles = (attrs >> TPM2_CC_ATTR_CHANDLES) & GENMASK(2, 0); + + /* + * just check the names, it's easy to make mistakes. This + * would happen if someone added a handle via + * tpm_buf_append_u32() instead of tpm_buf_append_name() + */ + for (i = 0; i < handles; i++) { + u32 handle = tpm_buf_read_u32(buf, &offset_s); + + if (auth->name_h[i] != handle) { + dev_err(&chip->dev, "TPM: handle %d wrong for name\n", + i); + return; + } + } + /* point offset_s to the start of the sessions */ + val = tpm_buf_read_u32(buf, &offset_s); + /* point offset_p to the start of the parameters */ + offset_p = offset_s + val; + for (i = 1; offset_s < offset_p; i++) { + u32 handle = tpm_buf_read_u32(buf, &offset_s); + u16 len; + u8 a; + + /* nonce (already in auth) */ + len = tpm_buf_read_u16(buf, &offset_s); + offset_s += len; + + a = tpm_buf_read_u8(buf, &offset_s); + + len = tpm_buf_read_u16(buf, &offset_s); + if (handle == auth->handle && auth->attrs == a) { + hmac = &buf->data[offset_s]; + /* + * save our session number so we know which + * session in the response belongs to us + */ + auth->session = i; + } + + offset_s += len; + } + if (offset_s != offset_p) { + dev_err(&chip->dev, "TPM session length is incorrect\n"); + return; + } + if (!hmac) { + dev_err(&chip->dev, "TPM could not find HMAC session\n"); + return; + } + + /* encrypt before HMAC */ + if (auth->attrs & TPM2_SA_DECRYPT) { + u16 len; + + /* need key and IV */ + tpm2_KDFa(auth->session_key, SHA256_DIGEST_SIZE + + auth->passphrase_len, "CFB", auth->our_nonce, + auth->tpm_nonce, AES_KEY_BYTES + AES_BLOCK_SIZE, + auth->scratch); + + len = tpm_buf_read_u16(buf, &offset_p); + aes_expandkey(&auth->aes_ctx, auth->scratch, AES_KEY_BYTES); + aescfb_encrypt(&auth->aes_ctx, &buf->data[offset_p], + &buf->data[offset_p], len, + auth->scratch + AES_KEY_BYTES); + /* reset p to beginning of parameters for HMAC */ + offset_p -= 2; + } + + sha256_init(&sctx); + /* ordinal is already BE */ + sha256_update(&sctx, (u8 *)&head->ordinal, sizeof(head->ordinal)); + /* add the handle names */ + for (i = 0; i < handles; i++) { + enum tpm2_mso_type mso = tpm2_handle_mso(auth->name_h[i]); + + if (mso == TPM2_MSO_PERSISTENT || + mso == TPM2_MSO_VOLATILE || + mso == TPM2_MSO_NVRAM) { + sha256_update(&sctx, auth->name[i], + name_size(auth->name[i])); + } else { + __be32 h = cpu_to_be32(auth->name_h[i]); + + sha256_update(&sctx, (u8 *)&h, 4); + } + } + if (offset_s != tpm_buf_length(buf)) + sha256_update(&sctx, &buf->data[offset_s], + tpm_buf_length(buf) - offset_s); + sha256_final(&sctx, cphash); + + /* now calculate the hmac */ + tpm2_hmac_init(&sctx, auth->session_key, sizeof(auth->session_key) + + auth->passphrase_len); + sha256_update(&sctx, cphash, sizeof(cphash)); + sha256_update(&sctx, auth->our_nonce, sizeof(auth->our_nonce)); + sha256_update(&sctx, auth->tpm_nonce, sizeof(auth->tpm_nonce)); + sha256_update(&sctx, &auth->attrs, 1); + tpm2_hmac_final(&sctx, auth->session_key, sizeof(auth->session_key) + + auth->passphrase_len, hmac); +} +EXPORT_SYMBOL(tpm_buf_fill_hmac_session); + +static int tpm2_parse_read_public(char *name, struct tpm_buf *buf) +{ + struct tpm_header *head = (struct tpm_header *)buf->data; + off_t offset = TPM_HEADER_SIZE; + u32 tot_len = be32_to_cpu(head->length); + u32 val; + + /* we're starting after the header so adjust the length */ + tot_len -= TPM_HEADER_SIZE; + + /* skip public */ + val = tpm_buf_read_u16(buf, &offset); + if (val > tot_len) + return -EINVAL; + offset += val; + /* name */ + val = tpm_buf_read_u16(buf, &offset); + if (val != name_size(&buf->data[offset])) + return -EINVAL; + memcpy(name, &buf->data[offset], val); + /* forget the rest */ + return 0; +} + +static int tpm2_read_public(struct tpm_chip *chip, u32 handle, char *name) +{ + struct tpm_buf buf; + int rc; + + rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_READ_PUBLIC); + if (rc) + return rc; + + tpm_buf_append_u32(&buf, handle); + rc = tpm_transmit_cmd(chip, &buf, 0, "read public"); + if (rc == TPM2_RC_SUCCESS) + rc = tpm2_parse_read_public(name, &buf); + + tpm_buf_destroy(&buf); + + return rc; +} + +/** + * tpm_buf_append_name() - add a handle area to the buffer + * @chip: the TPM chip structure + * @buf: The buffer to be appended + * @handle: The handle to be appended + * @name: The name of the handle (may be NULL) + * + * In order to compute session HMACs, we need to know the names of the + * objects pointed to by the handles. For most objects, this is simply + * the actual 4 byte handle or an empty buf (in these cases @name + * should be NULL) but for volatile objects, permanent objects and NV + * areas, the name is defined as the hash (according to the name + * algorithm which should be set to sha256) of the public area to + * which the two byte algorithm id has been appended. For these + * objects, the @name pointer should point to this. If a name is + * required but @name is NULL, then TPM2_ReadPublic() will be called + * on the handle to obtain the name. + * + * As with most tpm_buf operations, success is assumed because failure + * will be caused by an incorrect programming model and indicated by a + * kernel message. + */ +void tpm_buf_append_name(struct tpm_chip *chip, struct tpm_buf *buf, + u32 handle, u8 *name) +{ + enum tpm2_mso_type mso = tpm2_handle_mso(handle); + struct tpm2_auth *auth = chip->auth; + int slot; + + slot = (tpm_buf_length(buf) - TPM_HEADER_SIZE)/4; + if (slot >= AUTH_MAX_NAMES) { + dev_err(&chip->dev, "TPM: too many handles\n"); + return; + } + WARN(auth->session != tpm_buf_length(buf), + "name added in wrong place\n"); + tpm_buf_append_u32(buf, handle); + auth->session += 4; + + if (mso == TPM2_MSO_PERSISTENT || + mso == TPM2_MSO_VOLATILE || + mso == TPM2_MSO_NVRAM) { + if (!name) + tpm2_read_public(chip, handle, auth->name[slot]); + } else { + if (name) + dev_err(&chip->dev, "TPM: Handle does not require name but one is specified\n"); + } + + auth->name_h[slot] = handle; + if (name) + memcpy(auth->name[slot], name, name_size(name)); +} +EXPORT_SYMBOL(tpm_buf_append_name); + +/** + * tpm_buf_check_hmac_response() - check the TPM return HMAC for correctness + * @chip: the TPM chip structure + * @buf: the original command buffer (which now contains the response) + * @rc: the return code from tpm_transmit_cmd + * + * If @rc is non zero, @buf may not contain an actual return, so @rc + * is passed through as the return and the session cleaned up and + * de-allocated if required (this is required if + * TPM2_SA_CONTINUE_SESSION was not specified as a session flag). + * + * If @rc is zero, the response HMAC is computed against the returned + * @buf and matched to the TPM one in the session area. If there is a + * mismatch, an error is logged and -EINVAL returned. + * + * The reason for this is that the command issue and HMAC check + * sequence should look like: + * + * rc = tpm_transmit_cmd(...); + * rc = tpm_buf_check_hmac_response(&buf, auth, rc); + * if (rc) + * ... + * + * Which is easily layered into the current contrl flow. + * + * Returns: 0 on success or an error. + */ +int tpm_buf_check_hmac_response(struct tpm_chip *chip, struct tpm_buf *buf, + int rc) +{ + struct tpm_header *head = (struct tpm_header *)buf->data; + struct tpm2_auth *auth = chip->auth; + off_t offset_s, offset_p; + u8 rphash[SHA256_DIGEST_SIZE]; + u32 attrs; + struct sha256_state sctx; + u16 tag = be16_to_cpu(head->tag); + u32 cc = be32_to_cpu(auth->ordinal); + int parm_len, len, i, handles; + + if (auth->session >= TPM_HEADER_SIZE) { + WARN(1, "tpm session not filled correctly\n"); + goto out; + } + + if (rc != 0) + /* pass non success rc through and close the session */ + goto out; + + rc = -EINVAL; + if (tag != TPM2_ST_SESSIONS) { + dev_err(&chip->dev, "TPM: HMAC response check has no sessions tag\n"); + goto out; + } + + i = tpm2_find_cc(chip, cc); + if (i < 0) + goto out; + attrs = chip->cc_attrs_tbl[i]; + handles = (attrs >> TPM2_CC_ATTR_RHANDLE) & 1; + + /* point to area beyond handles */ + offset_s = TPM_HEADER_SIZE + handles * 4; + parm_len = tpm_buf_read_u32(buf, &offset_s); + offset_p = offset_s; + offset_s += parm_len; + /* skip over any sessions before ours */ + for (i = 0; i < auth->session - 1; i++) { + len = tpm_buf_read_u16(buf, &offset_s); + offset_s += len + 1; + len = tpm_buf_read_u16(buf, &offset_s); + offset_s += len; + } + /* TPM nonce */ + len = tpm_buf_read_u16(buf, &offset_s); + if (offset_s + len > tpm_buf_length(buf)) + goto out; + if (len != SHA256_DIGEST_SIZE) + goto out; + memcpy(auth->tpm_nonce, &buf->data[offset_s], len); + offset_s += len; + attrs = tpm_buf_read_u8(buf, &offset_s); + len = tpm_buf_read_u16(buf, &offset_s); + if (offset_s + len != tpm_buf_length(buf)) + goto out; + if (len != SHA256_DIGEST_SIZE) + goto out; + /* + * offset_s points to the HMAC. now calculate comparison, beginning + * with rphash + */ + sha256_init(&sctx); + /* yes, I know this is now zero, but it's what the standard says */ + sha256_update(&sctx, (u8 *)&head->return_code, + sizeof(head->return_code)); + /* ordinal is already BE */ + sha256_update(&sctx, (u8 *)&auth->ordinal, sizeof(auth->ordinal)); + sha256_update(&sctx, &buf->data[offset_p], parm_len); + sha256_final(&sctx, rphash); + + /* now calculate the hmac */ + tpm2_hmac_init(&sctx, auth->session_key, sizeof(auth->session_key) + + auth->passphrase_len); + sha256_update(&sctx, rphash, sizeof(rphash)); + sha256_update(&sctx, auth->tpm_nonce, sizeof(auth->tpm_nonce)); + sha256_update(&sctx, auth->our_nonce, sizeof(auth->our_nonce)); + sha256_update(&sctx, &auth->attrs, 1); + /* we're done with the rphash, so put our idea of the hmac there */ + tpm2_hmac_final(&sctx, auth->session_key, sizeof(auth->session_key) + + auth->passphrase_len, rphash); + if (memcmp(rphash, &buf->data[offset_s], SHA256_DIGEST_SIZE) == 0) { + rc = 0; + } else { + dev_err(&chip->dev, "TPM: HMAC check failed\n"); + goto out; + } + + /* now do response decryption */ + if (auth->attrs & TPM2_SA_ENCRYPT) { + /* need key and IV */ + tpm2_KDFa(auth->session_key, SHA256_DIGEST_SIZE + + auth->passphrase_len, "CFB", auth->tpm_nonce, + auth->our_nonce, AES_KEY_BYTES + AES_BLOCK_SIZE, + auth->scratch); + + len = tpm_buf_read_u16(buf, &offset_p); + aes_expandkey(&auth->aes_ctx, auth->scratch, AES_KEY_BYTES); + aescfb_decrypt(&auth->aes_ctx, &buf->data[offset_p], + &buf->data[offset_p], len, + auth->scratch + AES_KEY_BYTES); + } + + out: + if ((auth->attrs & TPM2_SA_CONTINUE_SESSION) == 0) { + if (rc) + /* manually close the session if it wasn't consumed */ + tpm2_flush_context(chip, auth->handle); + memzero_explicit(auth, sizeof(*auth)); + } else { + /* reset for next use */ + auth->session = TPM_HEADER_SIZE; + } + + return rc; +} +EXPORT_SYMBOL(tpm_buf_check_hmac_response); + +/** + * tpm2_end_auth_session() - kill the allocated auth session + * @chip: the TPM chip structure + * + * ends the session started by tpm2_start_auth_session and frees all + * the resources. Under normal conditions, + * tpm_buf_check_hmac_response() will correctly end the session if + * required, so this function is only for use in error legs that will + * bypass the normal invocation of tpm_buf_check_hmac_response(). + */ +void tpm2_end_auth_session(struct tpm_chip *chip) +{ + tpm2_flush_context(chip, chip->auth->handle); + memzero_explicit(chip->auth, sizeof(*chip->auth)); +} +EXPORT_SYMBOL(tpm2_end_auth_session); + +static int tpm2_parse_start_auth_session(struct tpm2_auth *auth, + struct tpm_buf *buf) +{ + struct tpm_header *head = (struct tpm_header *)buf->data; + u32 tot_len = be32_to_cpu(head->length); + off_t offset = TPM_HEADER_SIZE; + u32 val; + + /* we're starting after the header so adjust the length */ + tot_len -= TPM_HEADER_SIZE; + + /* should have handle plus nonce */ + if (tot_len != 4 + 2 + sizeof(auth->tpm_nonce)) + return -EINVAL; + + auth->handle = tpm_buf_read_u32(buf, &offset); + val = tpm_buf_read_u16(buf, &offset); + if (val != sizeof(auth->tpm_nonce)) + return -EINVAL; + memcpy(auth->tpm_nonce, &buf->data[offset], sizeof(auth->tpm_nonce)); + /* now compute the session key from the nonces */ + tpm2_KDFa(auth->salt, sizeof(auth->salt), "ATH", auth->tpm_nonce, + auth->our_nonce, sizeof(auth->session_key), + auth->session_key); + + return 0; +} + +static int tpm2_load_null(struct tpm_chip *chip, u32 *null_key) +{ + int rc; + unsigned int offset = 0; /* dummy offset for null seed context */ + u8 name[SHA256_DIGEST_SIZE + 2]; + + rc = tpm2_load_context(chip, chip->null_key_context, &offset, + null_key); + if (rc != -EINVAL) + return rc; + + /* an integrity failure may mean the TPM has been reset */ + dev_err(&chip->dev, "NULL key integrity failure!\n"); + /* check the null name against what we know */ + tpm2_create_primary(chip, TPM2_RH_NULL, NULL, name); + if (memcmp(name, chip->null_key_name, sizeof(name)) == 0) + /* name unchanged, assume transient integrity failure */ + return rc; + /* + * Fatal TPM failure: the NULL seed has actually changed, so + * the TPM must have been illegally reset. All in-kernel TPM + * operations will fail because the NULL primary can't be + * loaded to salt the sessions, but disable the TPM anyway so + * userspace programmes can't be compromised by it. + */ + dev_err(&chip->dev, "NULL name has changed, disabling TPM due to interference\n"); + chip->flags |= TPM_CHIP_FLAG_DISABLE; + + return rc; +} + +/** + * tpm2_start_auth_session() - create a HMAC authentication session with the TPM + * @chip: the TPM chip structure to create the session with + * + * This function loads the NULL seed from its saved context and starts + * an authentication session on the null seed, fills in the + * @chip->auth structure to contain all the session details necessary + * for performing the HMAC, encrypt and decrypt operations and + * returns. The NULL seed is flushed before this function returns. + * + * Return: zero on success or actual error encountered. + */ +int tpm2_start_auth_session(struct tpm_chip *chip) +{ + struct tpm_buf buf; + struct tpm2_auth *auth = chip->auth; + int rc; + u32 null_key; + + rc = tpm2_load_null(chip, &null_key); + if (rc) + goto out; + + auth->session = TPM_HEADER_SIZE; + + rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_START_AUTH_SESS); + if (rc) + goto out; + + /* salt key handle */ + tpm_buf_append_u32(&buf, null_key); + /* bind key handle */ + tpm_buf_append_u32(&buf, TPM2_RH_NULL); + /* nonce caller */ + get_random_bytes(auth->our_nonce, sizeof(auth->our_nonce)); + tpm_buf_append_u16(&buf, sizeof(auth->our_nonce)); + tpm_buf_append(&buf, auth->our_nonce, sizeof(auth->our_nonce)); + + /* append encrypted salt and squirrel away unencrypted in auth */ + tpm_buf_append_salt(&buf, chip); + /* session type (HMAC, audit or policy) */ + tpm_buf_append_u8(&buf, TPM2_SE_HMAC); + + /* symmetric encryption parameters */ + /* symmetric algorithm */ + tpm_buf_append_u16(&buf, TPM_ALG_AES); + /* bits for symmetric algorithm */ + tpm_buf_append_u16(&buf, AES_KEY_BITS); + /* symmetric algorithm mode (must be CFB) */ + tpm_buf_append_u16(&buf, TPM_ALG_CFB); + /* hash algorithm for session */ + tpm_buf_append_u16(&buf, TPM_ALG_SHA256); + + rc = tpm_transmit_cmd(chip, &buf, 0, "start auth session"); + tpm2_flush_context(chip, null_key); + + if (rc == TPM2_RC_SUCCESS) + rc = tpm2_parse_start_auth_session(auth, &buf); + + tpm_buf_destroy(&buf); + + if (rc) + goto out; + + out: + return rc; +} +EXPORT_SYMBOL(tpm2_start_auth_session); + +/** + * tpm2_parse_create_primary() - parse the data returned from TPM_CC_CREATE_PRIMARY + * + * @chip: The TPM the primary was created under + * @buf: The response buffer from the chip + * @handle: pointer to be filled in with the return handle of the primary + * @hierarchy: The hierarchy the primary was created for + * @name: pointer to be filled in with the primary key name + * + * Return: + * * 0 - OK + * * -errno - A system error + * * TPM_RC - A TPM error + */ +static int tpm2_parse_create_primary(struct tpm_chip *chip, struct tpm_buf *buf, + u32 *handle, u32 hierarchy, u8 *name) +{ + struct tpm_header *head = (struct tpm_header *)buf->data; + off_t offset_r = TPM_HEADER_SIZE, offset_t; + u16 len = TPM_HEADER_SIZE; + u32 total_len = be32_to_cpu(head->length); + u32 val, param_len, keyhandle; + + keyhandle = tpm_buf_read_u32(buf, &offset_r); + if (handle) + *handle = keyhandle; + else + tpm2_flush_context(chip, keyhandle); + + param_len = tpm_buf_read_u32(buf, &offset_r); + /* + * param_len doesn't include the header, but all the other + * lengths and offsets do, so add it to parm len to make + * the comparisons easier + */ + param_len += TPM_HEADER_SIZE; + + if (param_len + 8 > total_len) + return -EINVAL; + len = tpm_buf_read_u16(buf, &offset_r); + offset_t = offset_r; + if (name) { + /* + * now we have the public area, compute the name of + * the object + */ + put_unaligned_be16(TPM_ALG_SHA256, name); + sha256(&buf->data[offset_r], len, name + 2); + } + + /* validate the public key */ + val = tpm_buf_read_u16(buf, &offset_t); + + /* key type (must be what we asked for) */ + if (val != TPM_ALG_ECC) + return -EINVAL; + val = tpm_buf_read_u16(buf, &offset_t); + + /* name algorithm */ + if (val != TPM_ALG_SHA256) + return -EINVAL; + val = tpm_buf_read_u32(buf, &offset_t); + + /* object properties */ + if (val != TPM2_OA_TMPL) + return -EINVAL; + + /* auth policy (empty) */ + val = tpm_buf_read_u16(buf, &offset_t); + if (val != 0) + return -EINVAL; + + /* symmetric key parameters */ + val = tpm_buf_read_u16(buf, &offset_t); + if (val != TPM_ALG_AES) + return -EINVAL; + + /* symmetric key length */ + val = tpm_buf_read_u16(buf, &offset_t); + if (val != AES_KEY_BITS) + return -EINVAL; + + /* symmetric encryption scheme */ + val = tpm_buf_read_u16(buf, &offset_t); + if (val != TPM_ALG_CFB) + return -EINVAL; + + /* signing scheme */ + val = tpm_buf_read_u16(buf, &offset_t); + if (val != TPM_ALG_NULL) + return -EINVAL; + + /* ECC Curve */ + val = tpm_buf_read_u16(buf, &offset_t); + if (val != TPM2_ECC_NIST_P256) + return -EINVAL; + + /* KDF Scheme */ + val = tpm_buf_read_u16(buf, &offset_t); + if (val != TPM_ALG_NULL) + return -EINVAL; + + /* extract public key (x and y points) */ + val = tpm_buf_read_u16(buf, &offset_t); + if (val != EC_PT_SZ) + return -EINVAL; + memcpy(chip->null_ec_key_x, &buf->data[offset_t], val); + offset_t += val; + val = tpm_buf_read_u16(buf, &offset_t); + if (val != EC_PT_SZ) + return -EINVAL; + memcpy(chip->null_ec_key_y, &buf->data[offset_t], val); + offset_t += val; + + /* original length of the whole TPM2B */ + offset_r += len; + + /* should have exactly consumed the TPM2B public structure */ + if (offset_t != offset_r) + return -EINVAL; + if (offset_r > param_len) + return -EINVAL; + + /* creation data (skip) */ + len = tpm_buf_read_u16(buf, &offset_r); + offset_r += len; + if (offset_r > param_len) + return -EINVAL; + + /* creation digest (must be sha256) */ + len = tpm_buf_read_u16(buf, &offset_r); + offset_r += len; + if (len != SHA256_DIGEST_SIZE || offset_r > param_len) + return -EINVAL; + + /* TPMT_TK_CREATION follows */ + /* tag, must be TPM_ST_CREATION (0x8021) */ + val = tpm_buf_read_u16(buf, &offset_r); + if (val != TPM2_ST_CREATION || offset_r > param_len) + return -EINVAL; + + /* hierarchy */ + val = tpm_buf_read_u32(buf, &offset_r); + if (val != hierarchy || offset_r > param_len) + return -EINVAL; + + /* the ticket digest HMAC (might not be sha256) */ + len = tpm_buf_read_u16(buf, &offset_r); + offset_r += len; + if (offset_r > param_len) + return -EINVAL; + + /* + * finally we have the name, which is a sha256 digest plus a 2 + * byte algorithm type + */ + len = tpm_buf_read_u16(buf, &offset_r); + if (offset_r + len != param_len + 8) + return -EINVAL; + if (len != SHA256_DIGEST_SIZE + 2) + return -EINVAL; + + if (memcmp(chip->null_key_name, &buf->data[offset_r], + SHA256_DIGEST_SIZE + 2) != 0) { + dev_err(&chip->dev, "NULL Seed name comparison failed\n"); + return -EINVAL; + } + + return 0; +} + +/** + * tpm2_create_primary() - create a primary key using a fixed P-256 template + * + * @chip: the TPM chip to create under + * @hierarchy: The hierarchy handle to create under + * @handle: The returned volatile handle on success + * @name: The name of the returned key + * + * For platforms that might not have a persistent primary, this can be + * used to create one quickly on the fly (it uses Elliptic Curve not + * RSA, so even slow TPMs can create one fast). The template uses the + * TCG mandated H one for non-endorsement ECC primaries, i.e. P-256 + * elliptic curve (the only current one all TPM2s are required to + * have) a sha256 name hash and no policy. + * + * Return: + * * 0 - OK + * * -errno - A system error + * * TPM_RC - A TPM error + */ +static int tpm2_create_primary(struct tpm_chip *chip, u32 hierarchy, + u32 *handle, u8 *name) +{ + int rc; + struct tpm_buf buf; + struct tpm_buf template; + + rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_CREATE_PRIMARY); + if (rc) + return rc; + + rc = tpm_buf_init_sized(&template); + if (rc) { + tpm_buf_destroy(&buf); + return rc; + } + + /* + * create the template. Note: in order for userspace to + * verify the security of the system, it will have to create + * and certify this NULL primary, meaning all the template + * parameters will have to be identical, so conform exactly to + * the TCG TPM v2.0 Provisioning Guidance for the SRK ECC + * key H template (H has zero size unique points) + */ + + /* key type */ + tpm_buf_append_u16(&template, TPM_ALG_ECC); + + /* name algorithm */ + tpm_buf_append_u16(&template, TPM_ALG_SHA256); + + /* object properties */ + tpm_buf_append_u32(&template, TPM2_OA_TMPL); + + /* sauth policy (empty) */ + tpm_buf_append_u16(&template, 0); + + /* BEGIN parameters: key specific; for ECC*/ + + /* symmetric algorithm */ + tpm_buf_append_u16(&template, TPM_ALG_AES); + + /* bits for symmetric algorithm */ + tpm_buf_append_u16(&template, AES_KEY_BITS); + + /* algorithm mode (must be CFB) */ + tpm_buf_append_u16(&template, TPM_ALG_CFB); + + /* scheme (NULL means any scheme) */ + tpm_buf_append_u16(&template, TPM_ALG_NULL); + + /* ECC Curve ID */ + tpm_buf_append_u16(&template, TPM2_ECC_NIST_P256); + + /* KDF Scheme */ + tpm_buf_append_u16(&template, TPM_ALG_NULL); + + /* unique: key specific; for ECC it is two zero size points */ + tpm_buf_append_u16(&template, 0); + tpm_buf_append_u16(&template, 0); + + /* END parameters */ + + /* primary handle */ + tpm_buf_append_u32(&buf, hierarchy); + tpm_buf_append_empty_auth(&buf, TPM2_RS_PW); + + /* sensitive create size is 4 for two empty buffers */ + tpm_buf_append_u16(&buf, 4); + + /* sensitive create auth data (empty) */ + tpm_buf_append_u16(&buf, 0); + + /* sensitive create sensitive data (empty) */ + tpm_buf_append_u16(&buf, 0); + + /* the public template */ + tpm_buf_append(&buf, template.data, template.length); + tpm_buf_destroy(&template); + + /* outside info (empty) */ + tpm_buf_append_u16(&buf, 0); + + /* creation PCR (none) */ + tpm_buf_append_u32(&buf, 0); + + rc = tpm_transmit_cmd(chip, &buf, 0, + "attempting to create NULL primary"); + + if (rc == TPM2_RC_SUCCESS) + rc = tpm2_parse_create_primary(chip, &buf, handle, hierarchy, + name); + + tpm_buf_destroy(&buf); + + return rc; +} + +static int tpm2_create_null_primary(struct tpm_chip *chip) +{ + u32 null_key; + int rc; + + rc = tpm2_create_primary(chip, TPM2_RH_NULL, &null_key, + chip->null_key_name); + + if (rc == TPM2_RC_SUCCESS) { + unsigned int offset = 0; /* dummy offset for null key context */ + + rc = tpm2_save_context(chip, null_key, chip->null_key_context, + sizeof(chip->null_key_context), &offset); + tpm2_flush_context(chip, null_key); + } + + return rc; +} + +/** + * tpm2_sessions_init() - start of day initialization for the sessions code + * @chip: TPM chip + * + * Derive and context save the null primary and allocate memory in the + * struct tpm_chip for the authorizations. + */ +int tpm2_sessions_init(struct tpm_chip *chip) +{ + int rc; + + rc = tpm2_create_null_primary(chip); + if (rc) + dev_err(&chip->dev, "TPM: security failed (NULL seed derivation): %d\n", rc); + + chip->auth = kmalloc(sizeof(*chip->auth), GFP_KERNEL); + if (!chip->auth) + return -ENOMEM; + + return rc; +} diff --git a/drivers/char/tpm/tpm2-space.c b/drivers/char/tpm/tpm2-space.c index 363afdd4d1d3..4892d491da8d 100644 --- a/drivers/char/tpm/tpm2-space.c +++ b/drivers/char/tpm/tpm2-space.c @@ -68,8 +68,8 @@ void tpm2_del_space(struct tpm_chip *chip, struct tpm_space *space) kfree(space->session_buf); } -static int tpm2_load_context(struct tpm_chip *chip, u8 *buf, - unsigned int *offset, u32 *handle) +int tpm2_load_context(struct tpm_chip *chip, u8 *buf, + unsigned int *offset, u32 *handle) { struct tpm_buf tbuf; struct tpm2_context *ctx; @@ -105,6 +105,9 @@ static int tpm2_load_context(struct tpm_chip *chip, u8 *buf, *handle = 0; tpm_buf_destroy(&tbuf); return -ENOENT; + } else if (tpm2_rc_value(rc) == TPM2_RC_INTEGRITY) { + tpm_buf_destroy(&tbuf); + return -EINVAL; } else if (rc > 0) { dev_warn(&chip->dev, "%s: failed with a TPM error 0x%04X\n", __func__, rc); @@ -119,8 +122,8 @@ static int tpm2_load_context(struct tpm_chip *chip, u8 *buf, return 0; } -static int tpm2_save_context(struct tpm_chip *chip, u32 handle, u8 *buf, - unsigned int buf_size, unsigned int *offset) +int tpm2_save_context(struct tpm_chip *chip, u32 handle, u8 *buf, + unsigned int buf_size, unsigned int *offset) { struct tpm_buf tbuf; unsigned int body_size; diff --git a/drivers/char/tpm/tpm_infineon.c b/drivers/char/tpm/tpm_infineon.c index 9c924a1440a9..2d2ae37153ba 100644 --- a/drivers/char/tpm/tpm_infineon.c +++ b/drivers/char/tpm/tpm_infineon.c @@ -51,34 +51,40 @@ static struct tpm_inf_dev tpm_dev; static inline void tpm_data_out(unsigned char data, unsigned char offset) { +#ifdef CONFIG_HAS_IOPORT if (tpm_dev.iotype == TPM_INF_IO_PORT) outb(data, tpm_dev.data_regs + offset); else +#endif writeb(data, tpm_dev.mem_base + tpm_dev.data_regs + offset); } static inline unsigned char tpm_data_in(unsigned char offset) { +#ifdef CONFIG_HAS_IOPORT if (tpm_dev.iotype == TPM_INF_IO_PORT) return inb(tpm_dev.data_regs + offset); - else - return readb(tpm_dev.mem_base + tpm_dev.data_regs + offset); +#endif + return readb(tpm_dev.mem_base + tpm_dev.data_regs + offset); } static inline void tpm_config_out(unsigned char data, unsigned char offset) { +#ifdef CONFIG_HAS_IOPORT if (tpm_dev.iotype == TPM_INF_IO_PORT) outb(data, tpm_dev.config_port + offset); else +#endif writeb(data, tpm_dev.mem_base + tpm_dev.index_off + offset); } static inline unsigned char tpm_config_in(unsigned char offset) { +#ifdef CONFIG_HAS_IOPORT if (tpm_dev.iotype == TPM_INF_IO_PORT) return inb(tpm_dev.config_port + offset); - else - return readb(tpm_dev.mem_base + tpm_dev.index_off + offset); +#endif + return readb(tpm_dev.mem_base + tpm_dev.index_off + offset); } /* TPM header definitions */ diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c index 714070ebb6e7..176cd8dbf1db 100644 --- a/drivers/char/tpm/tpm_tis_core.c +++ b/drivers/char/tpm/tpm_tis_core.c @@ -1057,11 +1057,6 @@ static void tpm_tis_clkrun_enable(struct tpm_chip *chip, bool value) clkrun_val &= ~LPC_CLKRUN_EN; iowrite32(clkrun_val, data->ilb_base_addr + LPC_CNTRL_OFFSET); - /* - * Write any random value on port 0x80 which is on LPC, to make - * sure LPC clock is running before sending any TPM command. - */ - outb(0xCC, 0x80); } else { data->clkrun_enabled--; if (data->clkrun_enabled) @@ -1072,13 +1067,15 @@ static void tpm_tis_clkrun_enable(struct tpm_chip *chip, bool value) /* Enable LPC CLKRUN# */ clkrun_val |= LPC_CLKRUN_EN; iowrite32(clkrun_val, data->ilb_base_addr + LPC_CNTRL_OFFSET); - - /* - * Write any random value on port 0x80 which is on LPC, to make - * sure LPC clock is running before sending any TPM command. - */ - outb(0xCC, 0x80); } + +#ifdef CONFIG_HAS_IOPORT + /* + * Write any random value on port 0x80 which is on LPC, to make + * sure LPC clock is running before sending any TPM command. + */ + outb(0xCC, 0x80); +#endif } static const struct tpm_class_ops tpm_tis = { diff --git a/include/crypto/aes.h b/include/crypto/aes.h index 2090729701ab..9339da7c20a8 100644 --- a/include/crypto/aes.h +++ b/include/crypto/aes.h @@ -87,4 +87,9 @@ void aes_decrypt(const struct crypto_aes_ctx *ctx, u8 *out, const u8 *in); extern const u8 crypto_aes_sbox[]; extern const u8 crypto_aes_inv_sbox[]; +void aescfb_encrypt(const struct crypto_aes_ctx *ctx, u8 *dst, const u8 *src, + int len, const u8 iv[AES_BLOCK_SIZE]); +void aescfb_decrypt(const struct crypto_aes_ctx *ctx, u8 *dst, const u8 *src, + int len, const u8 iv[AES_BLOCK_SIZE]); + #endif diff --git a/include/keys/trusted_tpm.h b/include/keys/trusted_tpm.h index 7769b726863a..a088b33fd0e3 100644 --- a/include/keys/trusted_tpm.h +++ b/include/keys/trusted_tpm.h @@ -6,8 +6,6 @@ #include <linux/tpm_command.h> /* implementation specific TPM constants */ -#define MAX_BUF_SIZE 1024 -#define TPM_GETRANDOM_SIZE 14 #define TPM_SIZE_OFFSET 2 #define TPM_RETURN_OFFSET 6 #define TPM_DATA_OFFSET 10 diff --git a/include/linux/tpm.h b/include/linux/tpm.h index 4ee9d13749ad..c17e4efbb2e5 100644 --- a/include/linux/tpm.h +++ b/include/linux/tpm.h @@ -23,6 +23,7 @@ #include <linux/fs.h> #include <linux/highmem.h> #include <crypto/hash_info.h> +#include <crypto/aes.h> #define TPM_DIGEST_SIZE 20 /* Max TPM v1.2 PCR size */ #define TPM_MAX_DIGEST_SIZE SHA512_DIGEST_SIZE @@ -30,17 +31,28 @@ struct tpm_chip; struct trusted_key_payload; struct trusted_key_options; +/* opaque structure, holds auth session parameters like the session key */ +struct tpm2_auth; + +enum tpm2_session_types { + TPM2_SE_HMAC = 0x00, + TPM2_SE_POLICY = 0x01, + TPM2_SE_TRIAL = 0x02, +}; /* if you add a new hash to this, increment TPM_MAX_HASHES below */ enum tpm_algorithms { TPM_ALG_ERROR = 0x0000, TPM_ALG_SHA1 = 0x0004, + TPM_ALG_AES = 0x0006, TPM_ALG_KEYEDHASH = 0x0008, TPM_ALG_SHA256 = 0x000B, TPM_ALG_SHA384 = 0x000C, TPM_ALG_SHA512 = 0x000D, TPM_ALG_NULL = 0x0010, TPM_ALG_SM3_256 = 0x0012, + TPM_ALG_ECC = 0x0023, + TPM_ALG_CFB = 0x0043, }; /* @@ -49,6 +61,11 @@ enum tpm_algorithms { */ #define TPM_MAX_HASHES 5 +enum tpm2_curves { + TPM2_ECC_NONE = 0x0000, + TPM2_ECC_NIST_P256 = 0x0003, +}; + struct tpm_digest { u16 alg_id; u8 digest[TPM_MAX_DIGEST_SIZE]; @@ -116,6 +133,20 @@ struct tpm_chip_seqops { const struct seq_operations *seqops; }; +/* fixed define for the curve we use which is NIST_P256 */ +#define EC_PT_SZ 32 + +/* + * fixed define for the size of a name. This is actually HASHALG size + * plus 2, so 32 for SHA256 + */ +#define TPM2_NAME_SIZE 34 + +/* + * The maximum size for an object context + */ +#define TPM2_MAX_CONTEXT_SIZE 4096 + struct tpm_chip { struct device dev; struct device devs; @@ -170,6 +201,18 @@ struct tpm_chip { /* active locality */ int locality; + +#ifdef CONFIG_TCG_TPM2_HMAC + /* details for communication security via sessions */ + + /* saved context for NULL seed */ + u8 null_key_context[TPM2_MAX_CONTEXT_SIZE]; + /* name of NULL seed */ + u8 null_key_name[TPM2_NAME_SIZE]; + u8 null_ec_key_x[EC_PT_SZ]; + u8 null_ec_key_y[EC_PT_SZ]; + struct tpm2_auth *auth; +#endif }; #define TPM_HEADER_SIZE 10 @@ -194,6 +237,7 @@ enum tpm2_timeouts { enum tpm2_structures { TPM2_ST_NO_SESSIONS = 0x8001, TPM2_ST_SESSIONS = 0x8002, + TPM2_ST_CREATION = 0x8021, }; /* Indicates from what layer of the software stack the error comes from */ @@ -204,6 +248,7 @@ enum tpm2_return_codes { TPM2_RC_SUCCESS = 0x0000, TPM2_RC_HASH = 0x0083, /* RC_FMT1 */ TPM2_RC_HANDLE = 0x008B, + TPM2_RC_INTEGRITY = 0x009F, TPM2_RC_INITIALIZE = 0x0100, /* RC_VER1 */ TPM2_RC_FAILURE = 0x0101, TPM2_RC_DISABLED = 0x0120, @@ -231,6 +276,8 @@ enum tpm2_command_codes { TPM2_CC_CONTEXT_LOAD = 0x0161, TPM2_CC_CONTEXT_SAVE = 0x0162, TPM2_CC_FLUSH_CONTEXT = 0x0165, + TPM2_CC_READ_PUBLIC = 0x0173, + TPM2_CC_START_AUTH_SESS = 0x0176, TPM2_CC_VERIFY_SIGNATURE = 0x0177, TPM2_CC_GET_CAPABILITY = 0x017A, TPM2_CC_GET_RANDOM = 0x017B, @@ -243,9 +290,25 @@ enum tpm2_command_codes { }; enum tpm2_permanent_handles { + TPM2_RH_NULL = 0x40000007, TPM2_RS_PW = 0x40000009, }; +/* Most Significant Octet for key types */ +enum tpm2_mso_type { + TPM2_MSO_NVRAM = 0x01, + TPM2_MSO_SESSION = 0x02, + TPM2_MSO_POLICY = 0x03, + TPM2_MSO_PERMANENT = 0x40, + TPM2_MSO_VOLATILE = 0x80, + TPM2_MSO_PERSISTENT = 0x81, +}; + +static inline enum tpm2_mso_type tpm2_handle_mso(u32 handle) +{ + return handle >> 24; +} + enum tpm2_capabilities { TPM2_CAP_HANDLES = 1, TPM2_CAP_COMMANDS = 2, @@ -284,6 +347,7 @@ enum tpm_chip_flags { TPM_CHIP_FLAG_FIRMWARE_UPGRADE = BIT(7), TPM_CHIP_FLAG_SUSPENDED = BIT(8), TPM_CHIP_FLAG_HWRNG_DISABLED = BIT(9), + TPM_CHIP_FLAG_DISABLE = BIT(10), }; #define to_tpm_chip(d) container_of(d, struct tpm_chip, dev) @@ -297,28 +361,61 @@ struct tpm_header { }; } __packed; -/* A string buffer type for constructing TPM commands. This is based on the - * ideas of string buffer code in security/keys/trusted.h but is heap based - * in order to keep the stack usage minimal. - */ - enum tpm_buf_flags { + /* the capacity exceeded: */ TPM_BUF_OVERFLOW = BIT(0), + /* TPM2B format: */ + TPM_BUF_TPM2B = BIT(1), + /* read out of boundary: */ + TPM_BUF_BOUNDARY_ERROR = BIT(2), }; +/* + * A string buffer type for constructing TPM commands. + */ struct tpm_buf { - unsigned int flags; + u32 flags; + u32 length; u8 *data; + u8 handles; }; enum tpm2_object_attributes { TPM2_OA_FIXED_TPM = BIT(1), + TPM2_OA_ST_CLEAR = BIT(2), TPM2_OA_FIXED_PARENT = BIT(4), + TPM2_OA_SENSITIVE_DATA_ORIGIN = BIT(5), TPM2_OA_USER_WITH_AUTH = BIT(6), + TPM2_OA_ADMIN_WITH_POLICY = BIT(7), + TPM2_OA_NO_DA = BIT(10), + TPM2_OA_ENCRYPTED_DUPLICATION = BIT(11), + TPM2_OA_RESTRICTED = BIT(16), + TPM2_OA_DECRYPT = BIT(17), + TPM2_OA_SIGN = BIT(18), }; +/* + * definitions for the canonical template. These are mandated + * by the TCG key template documents + */ + +#define AES_KEY_BYTES AES_KEYSIZE_128 +#define AES_KEY_BITS (AES_KEY_BYTES*8) +#define TPM2_OA_TMPL (TPM2_OA_NO_DA | \ + TPM2_OA_FIXED_TPM | \ + TPM2_OA_FIXED_PARENT | \ + TPM2_OA_SENSITIVE_DATA_ORIGIN | \ + TPM2_OA_USER_WITH_AUTH | \ + TPM2_OA_DECRYPT | \ + TPM2_OA_RESTRICTED) + enum tpm2_session_attributes { TPM2_SA_CONTINUE_SESSION = BIT(0), + TPM2_SA_AUDIT_EXCLUSIVE = BIT(1), + TPM2_SA_AUDIT_RESET = BIT(3), + TPM2_SA_DECRYPT = BIT(5), + TPM2_SA_ENCRYPT = BIT(6), + TPM2_SA_AUDIT = BIT(7), }; struct tpm2_hash { @@ -326,84 +423,21 @@ struct tpm2_hash { unsigned int tpm_id; }; -static inline void tpm_buf_reset(struct tpm_buf *buf, u16 tag, u32 ordinal) -{ - struct tpm_header *head = (struct tpm_header *)buf->data; - - head->tag = cpu_to_be16(tag); - head->length = cpu_to_be32(sizeof(*head)); - head->ordinal = cpu_to_be32(ordinal); -} - -static inline int tpm_buf_init(struct tpm_buf *buf, u16 tag, u32 ordinal) -{ - buf->data = (u8 *)__get_free_page(GFP_KERNEL); - if (!buf->data) - return -ENOMEM; - - buf->flags = 0; - tpm_buf_reset(buf, tag, ordinal); - return 0; -} - -static inline void tpm_buf_destroy(struct tpm_buf *buf) -{ - free_page((unsigned long)buf->data); -} - -static inline u32 tpm_buf_length(struct tpm_buf *buf) -{ - struct tpm_header *head = (struct tpm_header *)buf->data; - - return be32_to_cpu(head->length); -} - -static inline u16 tpm_buf_tag(struct tpm_buf *buf) -{ - struct tpm_header *head = (struct tpm_header *)buf->data; - - return be16_to_cpu(head->tag); -} - -static inline void tpm_buf_append(struct tpm_buf *buf, - const unsigned char *new_data, - unsigned int new_len) -{ - struct tpm_header *head = (struct tpm_header *)buf->data; - u32 len = tpm_buf_length(buf); - - /* Return silently if overflow has already happened. */ - if (buf->flags & TPM_BUF_OVERFLOW) - return; - - if ((len + new_len) > PAGE_SIZE) { - WARN(1, "tpm_buf: overflow\n"); - buf->flags |= TPM_BUF_OVERFLOW; - return; - } - - memcpy(&buf->data[len], new_data, new_len); - head->length = cpu_to_be32(len + new_len); -} - -static inline void tpm_buf_append_u8(struct tpm_buf *buf, const u8 value) -{ - tpm_buf_append(buf, &value, 1); -} - -static inline void tpm_buf_append_u16(struct tpm_buf *buf, const u16 value) -{ - __be16 value2 = cpu_to_be16(value); - - tpm_buf_append(buf, (u8 *) &value2, 2); -} - -static inline void tpm_buf_append_u32(struct tpm_buf *buf, const u32 value) -{ - __be32 value2 = cpu_to_be32(value); - - tpm_buf_append(buf, (u8 *) &value2, 4); -} +int tpm_buf_init(struct tpm_buf *buf, u16 tag, u32 ordinal); +void tpm_buf_reset(struct tpm_buf *buf, u16 tag, u32 ordinal); +int tpm_buf_init_sized(struct tpm_buf *buf); +void tpm_buf_reset_sized(struct tpm_buf *buf); +void tpm_buf_destroy(struct tpm_buf *buf); +u32 tpm_buf_length(struct tpm_buf *buf); +void tpm_buf_append(struct tpm_buf *buf, const u8 *new_data, u16 new_length); +void tpm_buf_append_u8(struct tpm_buf *buf, const u8 value); +void tpm_buf_append_u16(struct tpm_buf *buf, const u16 value); +void tpm_buf_append_u32(struct tpm_buf *buf, const u32 value); +u8 tpm_buf_read_u8(struct tpm_buf *buf, off_t *offset); +u16 tpm_buf_read_u16(struct tpm_buf *buf, off_t *offset); +u32 tpm_buf_read_u32(struct tpm_buf *buf, off_t *offset); + +u8 *tpm_buf_parameters(struct tpm_buf *buf); /* * Check if TPM device is in the firmware upgrade mode. @@ -415,7 +449,7 @@ static inline bool tpm_is_firmware_upgrade(struct tpm_chip *chip) static inline u32 tpm2_rc_value(u32 rc) { - return (rc & BIT(7)) ? rc & 0xff : rc; + return (rc & BIT(7)) ? rc & 0xbf : rc; } #if defined(CONFIG_TCG_TPM) || defined(CONFIG_TCG_TPM_MODULE) @@ -429,10 +463,19 @@ extern int tpm_pcr_read(struct tpm_chip *chip, u32 pcr_idx, struct tpm_digest *digest); extern int tpm_pcr_extend(struct tpm_chip *chip, u32 pcr_idx, struct tpm_digest *digests); -extern int tpm_send(struct tpm_chip *chip, void *cmd, size_t buflen); extern int tpm_get_random(struct tpm_chip *chip, u8 *data, size_t max); extern struct tpm_chip *tpm_default_chip(void); void tpm2_flush_context(struct tpm_chip *chip, u32 handle); + +static inline void tpm_buf_append_empty_auth(struct tpm_buf *buf, u32 handle) +{ + /* simple authorization for empty auth */ + tpm_buf_append_u32(buf, 9); /* total length of auth */ + tpm_buf_append_u32(buf, handle); + tpm_buf_append_u16(buf, 0); /* nonce len */ + tpm_buf_append_u8(buf, 0); /* attributes */ + tpm_buf_append_u16(buf, 0); /* hmac len */ +} #else static inline int tpm_is_tpm2(struct tpm_chip *chip) { @@ -450,10 +493,6 @@ static inline int tpm_pcr_extend(struct tpm_chip *chip, u32 pcr_idx, return -ENODEV; } -static inline int tpm_send(struct tpm_chip *chip, void *cmd, size_t buflen) -{ - return -ENODEV; -} static inline int tpm_get_random(struct tpm_chip *chip, u8 *data, size_t max) { return -ENODEV; @@ -463,5 +502,102 @@ static inline struct tpm_chip *tpm_default_chip(void) { return NULL; } + +static inline void tpm_buf_append_empty_auth(struct tpm_buf *buf, u32 handle) +{ +} #endif +#ifdef CONFIG_TCG_TPM2_HMAC + +int tpm2_start_auth_session(struct tpm_chip *chip); +void tpm_buf_append_name(struct tpm_chip *chip, struct tpm_buf *buf, + u32 handle, u8 *name); +void tpm_buf_append_hmac_session(struct tpm_chip *chip, struct tpm_buf *buf, + u8 attributes, u8 *passphrase, + int passphraselen); +static inline void tpm_buf_append_hmac_session_opt(struct tpm_chip *chip, + struct tpm_buf *buf, + u8 attributes, + u8 *passphrase, + int passphraselen) +{ + tpm_buf_append_hmac_session(chip, buf, attributes, passphrase, + passphraselen); +} +void tpm_buf_fill_hmac_session(struct tpm_chip *chip, struct tpm_buf *buf); +int tpm_buf_check_hmac_response(struct tpm_chip *chip, struct tpm_buf *buf, + int rc); +void tpm2_end_auth_session(struct tpm_chip *chip); +#else +#include <asm/unaligned.h> + +static inline int tpm2_start_auth_session(struct tpm_chip *chip) +{ + return 0; +} +static inline void tpm2_end_auth_session(struct tpm_chip *chip) +{ +} +static inline void tpm_buf_append_name(struct tpm_chip *chip, + struct tpm_buf *buf, + u32 handle, u8 *name) +{ + tpm_buf_append_u32(buf, handle); + /* count the number of handles in the upper bits of flags */ + buf->handles++; +} +static inline void tpm_buf_append_hmac_session(struct tpm_chip *chip, + struct tpm_buf *buf, + u8 attributes, u8 *passphrase, + int passphraselen) +{ + /* offset tells us where the sessions area begins */ + int offset = buf->handles * 4 + TPM_HEADER_SIZE; + u32 len = 9 + passphraselen; + + if (tpm_buf_length(buf) != offset) { + /* not the first session so update the existing length */ + len += get_unaligned_be32(&buf->data[offset]); + put_unaligned_be32(len, &buf->data[offset]); + } else { + tpm_buf_append_u32(buf, len); + } + /* auth handle */ + tpm_buf_append_u32(buf, TPM2_RS_PW); + /* nonce */ + tpm_buf_append_u16(buf, 0); + /* attributes */ + tpm_buf_append_u8(buf, 0); + /* passphrase */ + tpm_buf_append_u16(buf, passphraselen); + tpm_buf_append(buf, passphrase, passphraselen); +} +static inline void tpm_buf_append_hmac_session_opt(struct tpm_chip *chip, + struct tpm_buf *buf, + u8 attributes, + u8 *passphrase, + int passphraselen) +{ + int offset = buf->handles * 4 + TPM_HEADER_SIZE; + struct tpm_header *head = (struct tpm_header *) buf->data; + + /* + * if the only sessions are optional, the command tag + * must change to TPM2_ST_NO_SESSIONS + */ + if (tpm_buf_length(buf) == offset) + head->tag = cpu_to_be16(TPM2_ST_NO_SESSIONS); +} +static inline void tpm_buf_fill_hmac_session(struct tpm_chip *chip, + struct tpm_buf *buf) +{ +} +static inline int tpm_buf_check_hmac_response(struct tpm_chip *chip, + struct tpm_buf *buf, + int rc) +{ + return rc; +} +#endif /* CONFIG_TCG_TPM2_HMAC */ + #endif diff --git a/lib/crypto/Kconfig b/lib/crypto/Kconfig index 45436bfc6dff..b01253cac70a 100644 --- a/lib/crypto/Kconfig +++ b/lib/crypto/Kconfig @@ -8,6 +8,11 @@ config CRYPTO_LIB_UTILS config CRYPTO_LIB_AES tristate +config CRYPTO_LIB_AESCFB + tristate + select CRYPTO_LIB_AES + select CRYPTO_LIB_UTILS + config CRYPTO_LIB_AESGCM tristate select CRYPTO_LIB_AES diff --git a/lib/crypto/Makefile b/lib/crypto/Makefile index 8d1446c2be71..969baab8c805 100644 --- a/lib/crypto/Makefile +++ b/lib/crypto/Makefile @@ -10,6 +10,9 @@ obj-$(CONFIG_CRYPTO_LIB_CHACHA_GENERIC) += libchacha.o obj-$(CONFIG_CRYPTO_LIB_AES) += libaes.o libaes-y := aes.o +obj-$(CONFIG_CRYPTO_LIB_AESCFB) += libaescfb.o +libaescfb-y := aescfb.o + obj-$(CONFIG_CRYPTO_LIB_AESGCM) += libaesgcm.o libaesgcm-y := aesgcm.o diff --git a/lib/crypto/aescfb.c b/lib/crypto/aescfb.c new file mode 100644 index 000000000000..749dc1258a44 --- /dev/null +++ b/lib/crypto/aescfb.c @@ -0,0 +1,257 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Minimal library implementation of AES in CFB mode + * + * Copyright 2023 Google LLC + */ + +#include <linux/module.h> + +#include <crypto/algapi.h> +#include <crypto/aes.h> + +#include <asm/irqflags.h> + +static void aescfb_encrypt_block(const struct crypto_aes_ctx *ctx, void *dst, + const void *src) +{ + unsigned long flags; + + /* + * In AES-CFB, the AES encryption operates on known 'plaintext' (the IV + * and ciphertext), making it susceptible to timing attacks on the + * encryption key. The AES library already mitigates this risk to some + * extent by pulling the entire S-box into the caches before doing any + * substitutions, but this strategy is more effective when running with + * interrupts disabled. + */ + local_irq_save(flags); + aes_encrypt(ctx, dst, src); + local_irq_restore(flags); +} + +/** + * aescfb_encrypt - Perform AES-CFB encryption on a block of data + * + * @ctx: The AES-CFB key schedule + * @dst: Pointer to the ciphertext output buffer + * @src: Pointer the plaintext (may equal @dst for encryption in place) + * @len: The size in bytes of the plaintext and ciphertext. + * @iv: The initialization vector (IV) to use for this block of data + */ +void aescfb_encrypt(const struct crypto_aes_ctx *ctx, u8 *dst, const u8 *src, + int len, const u8 iv[AES_BLOCK_SIZE]) +{ + u8 ks[AES_BLOCK_SIZE]; + const u8 *v = iv; + + while (len > 0) { + aescfb_encrypt_block(ctx, ks, v); + crypto_xor_cpy(dst, src, ks, min(len, AES_BLOCK_SIZE)); + v = dst; + + dst += AES_BLOCK_SIZE; + src += AES_BLOCK_SIZE; + len -= AES_BLOCK_SIZE; + } + + memzero_explicit(ks, sizeof(ks)); +} +EXPORT_SYMBOL(aescfb_encrypt); + +/** + * aescfb_decrypt - Perform AES-CFB decryption on a block of data + * + * @ctx: The AES-CFB key schedule + * @dst: Pointer to the plaintext output buffer + * @src: Pointer the ciphertext (may equal @dst for decryption in place) + * @len: The size in bytes of the plaintext and ciphertext. + * @iv: The initialization vector (IV) to use for this block of data + */ +void aescfb_decrypt(const struct crypto_aes_ctx *ctx, u8 *dst, const u8 *src, + int len, const u8 iv[AES_BLOCK_SIZE]) +{ + u8 ks[2][AES_BLOCK_SIZE]; + + aescfb_encrypt_block(ctx, ks[0], iv); + + for (int i = 0; len > 0; i ^= 1) { + if (len > AES_BLOCK_SIZE) + /* + * Generate the keystream for the next block before + * performing the XOR, as that may update in place and + * overwrite the ciphertext. + */ + aescfb_encrypt_block(ctx, ks[!i], src); + + crypto_xor_cpy(dst, src, ks[i], min(len, AES_BLOCK_SIZE)); + + dst += AES_BLOCK_SIZE; + src += AES_BLOCK_SIZE; + len -= AES_BLOCK_SIZE; + } + + memzero_explicit(ks, sizeof(ks)); +} +EXPORT_SYMBOL(aescfb_decrypt); + +MODULE_DESCRIPTION("Generic AES-CFB library"); +MODULE_AUTHOR("Ard Biesheuvel <ardb@kernel.org>"); +MODULE_LICENSE("GPL"); + +#ifndef CONFIG_CRYPTO_MANAGER_DISABLE_TESTS + +/* + * Test code below. Vectors taken from crypto/testmgr.h + */ + +static struct { + u8 ptext[64]; + u8 ctext[64]; + + u8 key[AES_MAX_KEY_SIZE]; + u8 iv[AES_BLOCK_SIZE]; + + int klen; + int len; +} const aescfb_tv[] __initconst = { + { /* From NIST SP800-38A */ + .key = "\x2b\x7e\x15\x16\x28\xae\xd2\xa6" + "\xab\xf7\x15\x88\x09\xcf\x4f\x3c", + .klen = 16, + .iv = "\x00\x01\x02\x03\x04\x05\x06\x07" + "\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f", + .ptext = "\x6b\xc1\xbe\xe2\x2e\x40\x9f\x96" + "\xe9\x3d\x7e\x11\x73\x93\x17\x2a" + "\xae\x2d\x8a\x57\x1e\x03\xac\x9c" + "\x9e\xb7\x6f\xac\x45\xaf\x8e\x51" + "\x30\xc8\x1c\x46\xa3\x5c\xe4\x11" + "\xe5\xfb\xc1\x19\x1a\x0a\x52\xef" + "\xf6\x9f\x24\x45\xdf\x4f\x9b\x17" + "\xad\x2b\x41\x7b\xe6\x6c\x37\x10", + .ctext = "\x3b\x3f\xd9\x2e\xb7\x2d\xad\x20" + "\x33\x34\x49\xf8\xe8\x3c\xfb\x4a" + "\xc8\xa6\x45\x37\xa0\xb3\xa9\x3f" + "\xcd\xe3\xcd\xad\x9f\x1c\xe5\x8b" + "\x26\x75\x1f\x67\xa3\xcb\xb1\x40" + "\xb1\x80\x8c\xf1\x87\xa4\xf4\xdf" + "\xc0\x4b\x05\x35\x7c\x5d\x1c\x0e" + "\xea\xc4\xc6\x6f\x9f\xf7\xf2\xe6", + .len = 64, + }, { + .key = "\x8e\x73\xb0\xf7\xda\x0e\x64\x52" + "\xc8\x10\xf3\x2b\x80\x90\x79\xe5" + "\x62\xf8\xea\xd2\x52\x2c\x6b\x7b", + .klen = 24, + .iv = "\x00\x01\x02\x03\x04\x05\x06\x07" + "\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f", + .ptext = "\x6b\xc1\xbe\xe2\x2e\x40\x9f\x96" + "\xe9\x3d\x7e\x11\x73\x93\x17\x2a" + "\xae\x2d\x8a\x57\x1e\x03\xac\x9c" + "\x9e\xb7\x6f\xac\x45\xaf\x8e\x51" + "\x30\xc8\x1c\x46\xa3\x5c\xe4\x11" + "\xe5\xfb\xc1\x19\x1a\x0a\x52\xef" + "\xf6\x9f\x24\x45\xdf\x4f\x9b\x17" + "\xad\x2b\x41\x7b\xe6\x6c\x37\x10", + .ctext = "\xcd\xc8\x0d\x6f\xdd\xf1\x8c\xab" + "\x34\xc2\x59\x09\xc9\x9a\x41\x74" + "\x67\xce\x7f\x7f\x81\x17\x36\x21" + "\x96\x1a\x2b\x70\x17\x1d\x3d\x7a" + "\x2e\x1e\x8a\x1d\xd5\x9b\x88\xb1" + "\xc8\xe6\x0f\xed\x1e\xfa\xc4\xc9" + "\xc0\x5f\x9f\x9c\xa9\x83\x4f\xa0" + "\x42\xae\x8f\xba\x58\x4b\x09\xff", + .len = 64, + }, { + .key = "\x60\x3d\xeb\x10\x15\xca\x71\xbe" + "\x2b\x73\xae\xf0\x85\x7d\x77\x81" + "\x1f\x35\x2c\x07\x3b\x61\x08\xd7" + "\x2d\x98\x10\xa3\x09\x14\xdf\xf4", + .klen = 32, + .iv = "\x00\x01\x02\x03\x04\x05\x06\x07" + "\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f", + .ptext = "\x6b\xc1\xbe\xe2\x2e\x40\x9f\x96" + "\xe9\x3d\x7e\x11\x73\x93\x17\x2a" + "\xae\x2d\x8a\x57\x1e\x03\xac\x9c" + "\x9e\xb7\x6f\xac\x45\xaf\x8e\x51" + "\x30\xc8\x1c\x46\xa3\x5c\xe4\x11" + "\xe5\xfb\xc1\x19\x1a\x0a\x52\xef" + "\xf6\x9f\x24\x45\xdf\x4f\x9b\x17" + "\xad\x2b\x41\x7b\xe6\x6c\x37\x10", + .ctext = "\xdc\x7e\x84\xbf\xda\x79\x16\x4b" + "\x7e\xcd\x84\x86\x98\x5d\x38\x60" + "\x39\xff\xed\x14\x3b\x28\xb1\xc8" + "\x32\x11\x3c\x63\x31\xe5\x40\x7b" + "\xdf\x10\x13\x24\x15\xe5\x4b\x92" + "\xa1\x3e\xd0\xa8\x26\x7a\xe2\xf9" + "\x75\xa3\x85\x74\x1a\xb9\xce\xf8" + "\x20\x31\x62\x3d\x55\xb1\xe4\x71", + .len = 64, + }, { /* > 16 bytes, not a multiple of 16 bytes */ + .key = "\x2b\x7e\x15\x16\x28\xae\xd2\xa6" + "\xab\xf7\x15\x88\x09\xcf\x4f\x3c", + .klen = 16, + .iv = "\x00\x01\x02\x03\x04\x05\x06\x07" + "\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f", + .ptext = "\x6b\xc1\xbe\xe2\x2e\x40\x9f\x96" + "\xe9\x3d\x7e\x11\x73\x93\x17\x2a" + "\xae", + .ctext = "\x3b\x3f\xd9\x2e\xb7\x2d\xad\x20" + "\x33\x34\x49\xf8\xe8\x3c\xfb\x4a" + "\xc8", + .len = 17, + }, { /* < 16 bytes */ + .key = "\x2b\x7e\x15\x16\x28\xae\xd2\xa6" + "\xab\xf7\x15\x88\x09\xcf\x4f\x3c", + .klen = 16, + .iv = "\x00\x01\x02\x03\x04\x05\x06\x07" + "\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f", + .ptext = "\x6b\xc1\xbe\xe2\x2e\x40\x9f", + .ctext = "\x3b\x3f\xd9\x2e\xb7\x2d\xad", + .len = 7, + }, +}; + +static int __init libaescfb_init(void) +{ + for (int i = 0; i < ARRAY_SIZE(aescfb_tv); i++) { + struct crypto_aes_ctx ctx; + u8 buf[64]; + + if (aes_expandkey(&ctx, aescfb_tv[i].key, aescfb_tv[i].klen)) { + pr_err("aes_expandkey() failed on vector %d\n", i); + return -ENODEV; + } + + aescfb_encrypt(&ctx, buf, aescfb_tv[i].ptext, aescfb_tv[i].len, + aescfb_tv[i].iv); + if (memcmp(buf, aescfb_tv[i].ctext, aescfb_tv[i].len)) { + pr_err("aescfb_encrypt() #1 failed on vector %d\n", i); + return -ENODEV; + } + + /* decrypt in place */ + aescfb_decrypt(&ctx, buf, buf, aescfb_tv[i].len, aescfb_tv[i].iv); + if (memcmp(buf, aescfb_tv[i].ptext, aescfb_tv[i].len)) { + pr_err("aescfb_decrypt() failed on vector %d\n", i); + return -ENODEV; + } + + /* encrypt in place */ + aescfb_encrypt(&ctx, buf, buf, aescfb_tv[i].len, aescfb_tv[i].iv); + if (memcmp(buf, aescfb_tv[i].ctext, aescfb_tv[i].len)) { + pr_err("aescfb_encrypt() #2 failed on vector %d\n", i); + + return -ENODEV; + } + + } + return 0; +} +module_init(libaescfb_init); + +static void __exit libaescfb_exit(void) +{ +} +module_exit(libaescfb_exit); +#endif diff --git a/security/keys/trusted-keys/trusted_tpm1.c b/security/keys/trusted-keys/trusted_tpm1.c index aa108bea6739..89c9798d1800 100644 --- a/security/keys/trusted-keys/trusted_tpm1.c +++ b/security/keys/trusted-keys/trusted_tpm1.c @@ -356,17 +356,28 @@ out: */ int trusted_tpm_send(unsigned char *cmd, size_t buflen) { + struct tpm_buf buf; int rc; if (!chip) return -ENODEV; + rc = tpm_try_get_ops(chip); + if (rc) + return rc; + + buf.flags = 0; + buf.length = buflen; + buf.data = cmd; dump_tpm_buf(cmd); - rc = tpm_send(chip, cmd, buflen); + rc = tpm_transmit_cmd(chip, &buf, 4, "sending data"); dump_tpm_buf(cmd); + if (rc > 0) - /* Can't return positive return codes values to keyctl */ + /* TPM error */ rc = -EPERM; + + tpm_put_ops(chip); return rc; } EXPORT_SYMBOL_GPL(trusted_tpm_send); @@ -407,7 +418,7 @@ static int osap(struct tpm_buf *tb, struct osapsess *s, tpm_buf_append_u32(tb, handle); tpm_buf_append(tb, ononce, TPM_NONCE_SIZE); - ret = trusted_tpm_send(tb->data, MAX_BUF_SIZE); + ret = trusted_tpm_send(tb->data, tb->length); if (ret < 0) return ret; @@ -431,7 +442,7 @@ int oiap(struct tpm_buf *tb, uint32_t *handle, unsigned char *nonce) return -ENODEV; tpm_buf_reset(tb, TPM_TAG_RQU_COMMAND, TPM_ORD_OIAP); - ret = trusted_tpm_send(tb->data, MAX_BUF_SIZE); + ret = trusted_tpm_send(tb->data, tb->length); if (ret < 0) return ret; @@ -543,7 +554,7 @@ static int tpm_seal(struct tpm_buf *tb, uint16_t keytype, tpm_buf_append_u8(tb, cont); tpm_buf_append(tb, td->pubauth, SHA1_DIGEST_SIZE); - ret = trusted_tpm_send(tb->data, MAX_BUF_SIZE); + ret = trusted_tpm_send(tb->data, tb->length); if (ret < 0) goto out; @@ -634,7 +645,7 @@ static int tpm_unseal(struct tpm_buf *tb, tpm_buf_append_u8(tb, cont); tpm_buf_append(tb, authdata2, SHA1_DIGEST_SIZE); - ret = trusted_tpm_send(tb->data, MAX_BUF_SIZE); + ret = trusted_tpm_send(tb->data, tb->length); if (ret < 0) { pr_info("authhmac failed (%d)\n", ret); return ret; diff --git a/security/keys/trusted-keys/trusted_tpm2.c b/security/keys/trusted-keys/trusted_tpm2.c index bc700f85f80b..dfeec06301ce 100644 --- a/security/keys/trusted-keys/trusted_tpm2.c +++ b/security/keys/trusted-keys/trusted_tpm2.c @@ -228,8 +228,9 @@ int tpm2_seal_trusted(struct tpm_chip *chip, struct trusted_key_payload *payload, struct trusted_key_options *options) { + off_t offset = TPM_HEADER_SIZE; + struct tpm_buf buf, sized; int blob_len = 0; - struct tpm_buf buf; u32 hash; u32 flags; int i; @@ -252,50 +253,58 @@ int tpm2_seal_trusted(struct tpm_chip *chip, if (rc) return rc; + rc = tpm2_start_auth_session(chip); + if (rc) + goto out_put; + rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_CREATE); if (rc) { - tpm_put_ops(chip); - return rc; + tpm2_end_auth_session(chip); + goto out_put; } - tpm_buf_append_u32(&buf, options->keyhandle); - tpm2_buf_append_auth(&buf, TPM2_RS_PW, - NULL /* nonce */, 0, - 0 /* session_attributes */, - options->keyauth /* hmac */, - TPM_DIGEST_SIZE); + rc = tpm_buf_init_sized(&sized); + if (rc) { + tpm_buf_destroy(&buf); + tpm2_end_auth_session(chip); + goto out_put; + } + + tpm_buf_append_name(chip, &buf, options->keyhandle, NULL); + tpm_buf_append_hmac_session(chip, &buf, TPM2_SA_DECRYPT, + options->keyauth, TPM_DIGEST_SIZE); /* sensitive */ - tpm_buf_append_u16(&buf, 4 + options->blobauth_len + payload->key_len); + tpm_buf_append_u16(&sized, options->blobauth_len); - tpm_buf_append_u16(&buf, options->blobauth_len); if (options->blobauth_len) - tpm_buf_append(&buf, options->blobauth, options->blobauth_len); + tpm_buf_append(&sized, options->blobauth, options->blobauth_len); - tpm_buf_append_u16(&buf, payload->key_len); - tpm_buf_append(&buf, payload->key, payload->key_len); + tpm_buf_append_u16(&sized, payload->key_len); + tpm_buf_append(&sized, payload->key, payload->key_len); + tpm_buf_append(&buf, sized.data, sized.length); /* public */ - tpm_buf_append_u16(&buf, 14 + options->policydigest_len); - tpm_buf_append_u16(&buf, TPM_ALG_KEYEDHASH); - tpm_buf_append_u16(&buf, hash); + tpm_buf_reset_sized(&sized); + tpm_buf_append_u16(&sized, TPM_ALG_KEYEDHASH); + tpm_buf_append_u16(&sized, hash); /* key properties */ flags = 0; flags |= options->policydigest_len ? 0 : TPM2_OA_USER_WITH_AUTH; - flags |= payload->migratable ? 0 : (TPM2_OA_FIXED_TPM | - TPM2_OA_FIXED_PARENT); - tpm_buf_append_u32(&buf, flags); + flags |= payload->migratable ? 0 : (TPM2_OA_FIXED_TPM | TPM2_OA_FIXED_PARENT); + tpm_buf_append_u32(&sized, flags); /* policy */ - tpm_buf_append_u16(&buf, options->policydigest_len); + tpm_buf_append_u16(&sized, options->policydigest_len); if (options->policydigest_len) - tpm_buf_append(&buf, options->policydigest, - options->policydigest_len); + tpm_buf_append(&sized, options->policydigest, options->policydigest_len); /* public parameters */ - tpm_buf_append_u16(&buf, TPM_ALG_NULL); - tpm_buf_append_u16(&buf, 0); + tpm_buf_append_u16(&sized, TPM_ALG_NULL); + tpm_buf_append_u16(&sized, 0); + + tpm_buf_append(&buf, sized.data, sized.length); /* outside info */ tpm_buf_append_u16(&buf, 0); @@ -305,28 +314,30 @@ int tpm2_seal_trusted(struct tpm_chip *chip, if (buf.flags & TPM_BUF_OVERFLOW) { rc = -E2BIG; + tpm2_end_auth_session(chip); goto out; } + tpm_buf_fill_hmac_session(chip, &buf); rc = tpm_transmit_cmd(chip, &buf, 4, "sealing data"); + rc = tpm_buf_check_hmac_response(chip, &buf, rc); if (rc) goto out; - blob_len = be32_to_cpup((__be32 *) &buf.data[TPM_HEADER_SIZE]); - if (blob_len > MAX_BLOB_SIZE) { + blob_len = tpm_buf_read_u32(&buf, &offset); + if (blob_len > MAX_BLOB_SIZE || buf.flags & TPM_BUF_BOUNDARY_ERROR) { rc = -E2BIG; goto out; } - if (tpm_buf_length(&buf) < TPM_HEADER_SIZE + 4 + blob_len) { + if (buf.length - offset < blob_len) { rc = -EFAULT; goto out; } - blob_len = tpm2_key_encode(payload, options, - &buf.data[TPM_HEADER_SIZE + 4], - blob_len); + blob_len = tpm2_key_encode(payload, options, &buf.data[offset], blob_len); out: + tpm_buf_destroy(&sized); tpm_buf_destroy(&buf); if (rc > 0) { @@ -340,6 +351,7 @@ out: else payload->blob_len = blob_len; +out_put: tpm_put_ops(chip); return rc; } @@ -409,25 +421,31 @@ static int tpm2_load_cmd(struct tpm_chip *chip, if (blob_len > payload->blob_len) return -E2BIG; - rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_LOAD); + rc = tpm2_start_auth_session(chip); if (rc) return rc; - tpm_buf_append_u32(&buf, options->keyhandle); - tpm2_buf_append_auth(&buf, TPM2_RS_PW, - NULL /* nonce */, 0, - 0 /* session_attributes */, - options->keyauth /* hmac */, - TPM_DIGEST_SIZE); + rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_LOAD); + if (rc) { + tpm2_end_auth_session(chip); + return rc; + } + + tpm_buf_append_name(chip, &buf, options->keyhandle, NULL); + tpm_buf_append_hmac_session(chip, &buf, 0, options->keyauth, + TPM_DIGEST_SIZE); tpm_buf_append(&buf, blob, blob_len); if (buf.flags & TPM_BUF_OVERFLOW) { rc = -E2BIG; + tpm2_end_auth_session(chip); goto out; } + tpm_buf_fill_hmac_session(chip, &buf); rc = tpm_transmit_cmd(chip, &buf, 4, "loading blob"); + rc = tpm_buf_check_hmac_response(chip, &buf, rc); if (!rc) *blob_handle = be32_to_cpup( (__be32 *) &buf.data[TPM_HEADER_SIZE]); @@ -465,20 +483,44 @@ static int tpm2_unseal_cmd(struct tpm_chip *chip, u8 *data; int rc; - rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_UNSEAL); + rc = tpm2_start_auth_session(chip); if (rc) return rc; - tpm_buf_append_u32(&buf, blob_handle); - tpm2_buf_append_auth(&buf, - options->policyhandle ? - options->policyhandle : TPM2_RS_PW, - NULL /* nonce */, 0, - TPM2_SA_CONTINUE_SESSION, - options->blobauth /* hmac */, - options->blobauth_len); + rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_UNSEAL); + if (rc) { + tpm2_end_auth_session(chip); + return rc; + } + + tpm_buf_append_name(chip, &buf, blob_handle, NULL); + + if (!options->policyhandle) { + tpm_buf_append_hmac_session(chip, &buf, TPM2_SA_ENCRYPT, + options->blobauth, + options->blobauth_len); + } else { + /* + * FIXME: The policy session was generated outside the + * kernel so we don't known the nonce and thus can't + * calculate a HMAC on it. Therefore, the user can + * only really use TPM2_PolicyPassword and we must + * send down the plain text password, which could be + * intercepted. We can still encrypt the returned + * key, but that's small comfort since the interposer + * could repeat our actions with the exfiltrated + * password. + */ + tpm2_buf_append_auth(&buf, options->policyhandle, + NULL /* nonce */, 0, 0, + options->blobauth, options->blobauth_len); + tpm_buf_append_hmac_session_opt(chip, &buf, TPM2_SA_ENCRYPT, + NULL, 0); + } + tpm_buf_fill_hmac_session(chip, &buf); rc = tpm_transmit_cmd(chip, &buf, 6, "unsealing"); + rc = tpm_buf_check_hmac_response(chip, &buf, rc); if (rc > 0) rc = -EPERM; |