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* evm: prevent racing during tfm allocationDmitry Kasatkin2011-12-201-0/+9
| | | | | | | | | There is a small chance of racing during tfm allocation. This patch fixes it. Signed-off-by: Dmitry Kasatkin <dmitry.kasatkin@intel.com> Acked-by: Mimi Zohar <zohar@us.ibm.com> Signed-off-by: James Morris <jmorris@namei.org>
* evm: key must be set once during initializationDmitry Kasatkin2011-12-201-4/+6
| | | | | | | | | | | On multi-core systems, setting of the key before every caclculation, causes invalid HMAC calculation for other tfm users, because internal state (ipad, opad) can be invalid before set key call returns. It needs to be set only once during initialization. Signed-off-by: Dmitry Kasatkin <dmitry.kasatkin@intel.com> Acked-by: Mimi Zohar <zohar@us.ibm.com> Signed-off-by: James Morris <jmorris@namei.org>
* evm: permit mode bits to be updatedMimi Zohar2011-09-141-17/+13
| | | | | | | | | | | Before permitting 'security.evm' to be updated, 'security.evm' must exist and be valid. In the case that there are no existing EVM protected xattrs, it is safe for posix acls to update the mode bits. To differentiate between no 'security.evm' xattr and no xattrs used to calculate 'security.evm', this patch defines INTEGRITY_NOXATTR. Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
* evm: posix acls modify i_modeMimi Zohar2011-09-143-5/+46
| | | | | | | | | | The posix xattr acls are 'system' prefixed, which normally would not affect security.evm. An interesting side affect of writing posix xattr acls is their modifying of the i_mode, which is included in security.evm. This patch updates security.evm when posix xattr acls are written. Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
* evm: limit verifying current security.evm integrityMimi Zohar2011-09-141-34/+24
| | | | | | | | | evm_protect_xattr unnecessarily validates the current security.evm integrity, before updating non-evm protected extended attributes and other file metadata. This patch limits validating the current security.evm integrity to evm protected metadata. Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
* evm: remove TCG_TPM dependencyMimi Zohar2011-09-141-2/+1
| | | | | | | | | | | | | | | | | | All tristates selected by EVM(boolean) are forced to be builtin, except in the TCG_TPM(tristate) dependency case. Arnaud Lacombe summarizes the Kconfig bug as, "So it would seem direct dependency state influence the state of reverse dependencies.." For a detailed explanation, refer to Arnaud Lacombe's posting http://lkml.org/lkml/2011/8/23/498. With the "encrypted-keys: remove trusted-keys dependency" patch, EVM can now be built without a dependency on TCG_TPM. The trusted-keys dependency requires trusted-keys to either be builtin or not selected. This dependency will prevent the boolean/tristate mismatch from occuring. Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>, Randy Dunlap <rdunlap@xenotimenet> Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
* evm: add Kconfig TCG_TPM dependencyMimi Zohar2011-08-181-1/+1
| | | | | | | | | | | | | | | Although the EVM encrypted-key should be encrypted/decrypted using a trusted-key, a user-defined key could be used instead. When using a user- defined key, a TCG_TPM dependency should not be required. Unfortunately, the encrypted-key code needs to be refactored a bit in order to remove this dependency. This patch adds the TCG_TPM dependency. Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>, Randy Dunlap <rdunlap@xenotimenet> Signed-off-by: Mimi Zohar <zohar@us.ibm.com> Signed-off-by: James Morris <jmorris@namei.org>
* evm: fix evm_inode_init_security return codeMimi Zohar2011-08-111-1/+1
| | | | | | | | evm_inode_init_security() should return 0, when EVM is not enabled. (Returning an error is a remnant of evm_inode_post_init_security.) Signed-off-by: Mimi Zohar <zohar@us.ibm.com> Signed-off-by: James Morris <jmorris@namei.org>
* EVM: ensure trusted and encypted key symbols are available to EVMJames Morris2011-08-091-1/+3
| | | | | | | | | Select trusted and encrypted keys if EVM is selected, to ensure the requisite symbols are available. Otherwise, these can be selected as modules while EVM is static, leading to a kernel build failure. Signed-off-by: James Morris <jmorris@namei.org>
* evm: add evm_inode_setattr to prevent updating an invalid security.evmMimi Zohar2011-07-181-0/+15
| | | | | | | Permit changing of security.evm only when valid, unless in fixmode. Reported-by: Roberto Sassu <roberto.sassu@polito.it> Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
* evm: permit only valid security.evm xattrs to be updatedMimi Zohar2011-07-181-14/+63
| | | | | | | | | | | | | In addition to requiring CAP_SYS_ADMIN permission to modify/delete security.evm, prohibit invalid security.evm xattrs from changing, unless in fixmode. This patch prevents inadvertent 'fixing' of security.evm to reflect offline modifications. Changelog v7: - rename boot paramater 'evm_mode' to 'evm' Reported-by: Roberto Sassu <roberto.sassu@polito.it> Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
* evm: replace hmac_status with evm_statusDmitry Kasatkin2011-07-181-7/+7
| | | | | | | We will use digital signatures in addtion to hmac. Signed-off-by: Dmitry Kasatkin <dmitry.kasatkin@nokia.com> Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
* evm: evm_verify_hmac must not return INTEGRITY_UNKNOWNDmitry Kasatkin2011-07-181-6/+5
| | | | | | | | | | | | | | | | | | | If EVM is not supported or enabled, evm_verify_hmac() returns INTEGRITY_UNKNOWN, which ima_appraise_measurement() ignores and sets the appraisal status based solely on the security.ima verification. evm_verify_hmac() also returns INTEGRITY_UNKNOWN for other failures, such as temporary failures like -ENOMEM, resulting in possible attack vectors. This patch changes the default return code for temporary/unexpected failures, like -ENOMEM, from INTEGRITY_UNKNOWN to INTEGRITY_FAIL, making evm_verify_hmac() fail safe. As a result, failures need to be re-evaluated in order to catch both temporary errors, such as the -ENOMEM, as well as errors that have been resolved in fix mode. Signed-off-by: Dmitry Kasatkin <dmitry.kasatkin@nokia.com> Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
* evm: additional parameter to pass integrity cache entry 'iint'Dmitry Kasatkin2011-07-181-10/+8
| | | | | | | Additional iint parameter allows to skip lookup in the cache. Signed-off-by: Dmitry Kasatkin <dmitry.kasatkin@nokia.com> Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
* evm: crypto hash replaced by shashDmitry Kasatkin2011-07-183-45/+57
| | | | | | | | | | | | Using shash is more efficient, because the algorithm is allocated only once. Only the descriptor to store the hash state needs to be allocated for every operation. Changelog v6: - check for crypto_shash_setkey failure Signed-off-by: Dmitry Kasatkin <dmitry.kasatkin@nokia.com> Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
* evm: add evm_inode_init_security to initialize new filesMimi Zohar2011-07-183-0/+61
| | | | | | | | | | | | | Initialize 'security.evm' for new files. Changelog v7: - renamed evm_inode_post_init_security to evm_inode_init_security - moved struct xattr definition to earlier patch - allocate xattr name Changelog v6: - Use 'struct evm_ima_xattr_data' Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
* security: imbed evm calls in security hooksMimi Zohar2011-07-181-0/+1
| | | | | | | | | | | | | | | | Imbed the evm calls evm_inode_setxattr(), evm_inode_post_setxattr(), evm_inode_removexattr() in the security hooks. evm_inode_setxattr() protects security.evm xattr. evm_inode_post_setxattr() and evm_inode_removexattr() updates the hmac associated with an inode. (Assumes an LSM module protects the setting/removing of xattr.) Changelog: - Don't define evm_verifyxattr(), unless CONFIG_INTEGRITY is enabled. - xattr_name is a 'const', value is 'void *' Signed-off-by: Mimi Zohar <zohar@us.ibm.com> Acked-by: Serge Hallyn <serge.hallyn@ubuntu.com>
* evm: add support for different security.evm data typesDmitry Kasatkin2011-07-182-9/+12
| | | | | | | | | | | | | | | | | | | EVM protects a file's security extended attributes(xattrs) against integrity attacks. The current patchset maintains an HMAC-sha1 value across the security xattrs, storing the value as the extended attribute 'security.evm'. We anticipate other methods for protecting the security extended attributes. This patch reserves the first byte of 'security.evm' as a place holder for the type of method. Changelog v6: - move evm_ima_xattr_type definition to security/integrity/integrity.h - defined a structure for the EVM xattr called evm_ima_xattr_data (based on Serge Hallyn's suggestion) - removed unnecessary memset Signed-off-by: Dmitry Kasatkin <dmitry.kasatkin@nokia.com> Signed-off-by: Mimi Zohar <zohar@us.ibm.com> Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
* evm: re-releaseMimi Zohar2011-07-186-0/+626
EVM protects a file's security extended attributes(xattrs) against integrity attacks. This patchset provides the framework and an initial method. The initial method maintains an HMAC-sha1 value across the security extended attributes, storing the HMAC value as the extended attribute 'security.evm'. Other methods of validating the integrity of a file's metadata will be posted separately (eg. EVM-digital-signatures). While this patchset does authenticate the security xattrs, and cryptographically binds them to the inode, coming extensions will bind other directory and inode metadata for more complete protection. To help simplify the review and upstreaming process, each extension will be posted separately (eg. IMA-appraisal, IMA-appraisal-directory). For a general overview of the proposed Linux integrity subsystem, refer to Dave Safford's whitepaper: http://downloads.sf.net/project/linux-ima/linux-ima/Integrity_overview.pdf. EVM depends on the Kernel Key Retention System to provide it with a trusted/encrypted key for the HMAC-sha1 operation. The key is loaded onto the root's keyring using keyctl. Until EVM receives notification that the key has been successfully loaded onto the keyring (echo 1 > <securityfs>/evm), EVM can not create or validate the 'security.evm' xattr, but returns INTEGRITY_UNKNOWN. Loading the key and signaling EVM should be done as early as possible. Normally this is done in the initramfs, which has already been measured as part of the trusted boot. For more information on creating and loading existing trusted/encrypted keys, refer to Documentation/keys-trusted-encrypted.txt. A sample dracut patch, which loads the trusted/encrypted key and enables EVM, is available from http://linux-ima.sourceforge.net/#EVM. Based on the LSMs enabled, the set of EVM protected security xattrs is defined at compile. EVM adds the following three calls to the existing security hooks: evm_inode_setxattr(), evm_inode_post_setxattr(), and evm_inode_removexattr. To initialize and update the 'security.evm' extended attribute, EVM defines three calls: evm_inode_post_init(), evm_inode_post_setattr() and evm_inode_post_removexattr() hooks. To verify the integrity of a security xattr, EVM exports evm_verifyxattr(). Changelog v7: - Fixed URL in EVM ABI documentation Changelog v6: (based on Serge Hallyn's review) - fix URL in patch description - remove evm_hmac_size definition - use SHA1_DIGEST_SIZE (removed both MAX_DIGEST_SIZE and evm_hmac_size) - moved linux include before other includes - test for crypto_hash_setkey failure - fail earlier for invalid key - clear entire encrypted key, even on failure - check xattr name length before comparing xattr names Changelog: - locking based on i_mutex, remove evm_mutex - using trusted/encrypted keys for storing the EVM key used in the HMAC-sha1 operation. - replaced crypto hash with shash (Dmitry Kasatkin) - support for additional methods of verifying the security xattrs (Dmitry Kasatkin) - iint not allocated for all regular files, but only for those appraised - Use cap_sys_admin in lieu of cap_mac_admin - Use __vfs_setxattr_noperm(), without permission checks, from EVM Signed-off-by: Mimi Zohar <zohar@us.ibm.com> Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
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