diff options
Diffstat (limited to 'fs/crypto/policy.c')
| -rw-r--r-- | fs/crypto/policy.c | 228 |
1 files changed, 210 insertions, 18 deletions
diff --git a/fs/crypto/policy.c b/fs/crypto/policy.c index cf2a9d26ef7d..2d73fd39ad96 100644 --- a/fs/crypto/policy.c +++ b/fs/crypto/policy.c @@ -11,12 +11,15 @@ */ #include <linux/random.h> +#include <linux/seq_file.h> #include <linux/string.h> #include <linux/mount.h> #include "fscrypt_private.h" /** - * fscrypt_policies_equal - check whether two encryption policies are the same + * fscrypt_policies_equal() - check whether two encryption policies are the same + * @policy1: the first policy + * @policy2: the second policy * * Return: %true if equal, else %false */ @@ -66,18 +69,28 @@ static bool supported_direct_key_modes(const struct inode *inode, return true; } -static bool supported_iv_ino_lblk_64_policy( - const struct fscrypt_policy_v2 *policy, - const struct inode *inode) +static bool supported_iv_ino_lblk_policy(const struct fscrypt_policy_v2 *policy, + const struct inode *inode, + const char *type, + int max_ino_bits, int max_lblk_bits) { struct super_block *sb = inode->i_sb; int ino_bits = 64, lblk_bits = 64; - if (policy->flags & FSCRYPT_POLICY_FLAG_DIRECT_KEY) { + /* + * IV_INO_LBLK_* exist only because of hardware limitations, and + * currently the only known use case for them involves AES-256-XTS. + * That's also all we test currently. For these reasons, for now only + * allow AES-256-XTS here. This can be relaxed later if a use case for + * IV_INO_LBLK_* with other encryption modes arises. + */ + if (policy->contents_encryption_mode != FSCRYPT_MODE_AES_256_XTS) { fscrypt_warn(inode, - "The DIRECT_KEY and IV_INO_LBLK_64 flags are mutually exclusive"); + "Can't use %s policy with contents mode other than AES-256-XTS", + type); return false; } + /* * It's unsafe to include inode numbers in the IVs if the filesystem can * potentially renumber inodes, e.g. via filesystem shrinking. @@ -85,16 +98,22 @@ static bool supported_iv_ino_lblk_64_policy( if (!sb->s_cop->has_stable_inodes || !sb->s_cop->has_stable_inodes(sb)) { fscrypt_warn(inode, - "Can't use IV_INO_LBLK_64 policy on filesystem '%s' because it doesn't have stable inode numbers", - sb->s_id); + "Can't use %s policy on filesystem '%s' because it doesn't have stable inode numbers", + type, sb->s_id); return false; } if (sb->s_cop->get_ino_and_lblk_bits) sb->s_cop->get_ino_and_lblk_bits(sb, &ino_bits, &lblk_bits); - if (ino_bits > 32 || lblk_bits > 32) { + if (ino_bits > max_ino_bits) { fscrypt_warn(inode, - "Can't use IV_INO_LBLK_64 policy on filesystem '%s' because it doesn't use 32-bit inode and block numbers", - sb->s_id); + "Can't use %s policy on filesystem '%s' because its inode numbers are too long", + type, sb->s_id); + return false; + } + if (lblk_bits > max_lblk_bits) { + fscrypt_warn(inode, + "Can't use %s policy on filesystem '%s' because its block numbers are too long", + type, sb->s_id); return false; } return true; @@ -137,6 +156,8 @@ static bool fscrypt_supported_v1_policy(const struct fscrypt_policy_v1 *policy, static bool fscrypt_supported_v2_policy(const struct fscrypt_policy_v2 *policy, const struct inode *inode) { + int count = 0; + if (!fscrypt_valid_enc_modes(policy->contents_encryption_mode, policy->filenames_encryption_mode)) { fscrypt_warn(inode, @@ -152,13 +173,29 @@ static bool fscrypt_supported_v2_policy(const struct fscrypt_policy_v2 *policy, return false; } + count += !!(policy->flags & FSCRYPT_POLICY_FLAG_DIRECT_KEY); + count += !!(policy->flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_64); + count += !!(policy->flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32); + if (count > 1) { + fscrypt_warn(inode, "Mutually exclusive encryption flags (0x%02x)", + policy->flags); + return false; + } + if ((policy->flags & FSCRYPT_POLICY_FLAG_DIRECT_KEY) && !supported_direct_key_modes(inode, policy->contents_encryption_mode, policy->filenames_encryption_mode)) return false; if ((policy->flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_64) && - !supported_iv_ino_lblk_64_policy(policy, inode)) + !supported_iv_ino_lblk_policy(policy, inode, "IV_INO_LBLK_64", + 32, 32)) + return false; + + if ((policy->flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32) && + /* This uses hashed inode numbers, so ino_bits doesn't matter. */ + !supported_iv_ino_lblk_policy(policy, inode, "IV_INO_LBLK_32", + INT_MAX, 32)) return false; if (memchr_inv(policy->__reserved, 0, sizeof(policy->__reserved))) { @@ -170,7 +207,9 @@ static bool fscrypt_supported_v2_policy(const struct fscrypt_policy_v2 *policy, } /** - * fscrypt_supported_policy - check whether an encryption policy is supported + * fscrypt_supported_policy() - check whether an encryption policy is supported + * @policy_u: the encryption policy + * @inode: the inode on which the policy will be used * * Given an encryption policy, check whether all its encryption modes and other * settings are supported by this kernel on the given inode. (But we don't @@ -192,7 +231,10 @@ bool fscrypt_supported_policy(const union fscrypt_policy *policy_u, } /** - * fscrypt_new_context_from_policy - create a new fscrypt_context from a policy + * fscrypt_new_context_from_policy() - create a new fscrypt_context from + * an fscrypt_policy + * @ctx_u: output context + * @policy_u: input policy * * Create an fscrypt_context for an inode that is being assigned the given * encryption policy. A new nonce is randomly generated. @@ -242,7 +284,11 @@ static int fscrypt_new_context_from_policy(union fscrypt_context *ctx_u, } /** - * fscrypt_policy_from_context - convert an fscrypt_context to an fscrypt_policy + * fscrypt_policy_from_context() - convert an fscrypt_context to + * an fscrypt_policy + * @policy_u: output policy + * @ctx_u: input context + * @ctx_size: size of input context in bytes * * Given an fscrypt_context, build the corresponding fscrypt_policy. * @@ -258,7 +304,7 @@ int fscrypt_policy_from_context(union fscrypt_policy *policy_u, { memset(policy_u, 0, sizeof(*policy_u)); - if (ctx_size <= 0 || ctx_size != fscrypt_context_size(ctx_u)) + if (!fscrypt_context_is_valid(ctx_u, ctx_size)) return -EINVAL; switch (ctx_u->version) { @@ -306,7 +352,7 @@ static int fscrypt_get_policy(struct inode *inode, union fscrypt_policy *policy) union fscrypt_context ctx; int ret; - ci = READ_ONCE(inode->i_crypt_info); + ci = fscrypt_get_info(inode); if (ci) { /* key available, use the cached policy */ *policy = ci->ci_policy; @@ -354,6 +400,9 @@ static int set_encryption_policy(struct inode *inode, policy->v2.master_key_identifier); if (err) return err; + if (policy->v2.flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32) + pr_warn_once("%s (pid %d) is setting an IV_INO_LBLK_32 encryption policy. This should only be used if there are certain hardware limitations.\n", + current->comm, current->pid); break; default: WARN_ON(1); @@ -481,6 +530,25 @@ int fscrypt_ioctl_get_policy_ex(struct file *filp, void __user *uarg) } EXPORT_SYMBOL_GPL(fscrypt_ioctl_get_policy_ex); +/* FS_IOC_GET_ENCRYPTION_NONCE: retrieve file's encryption nonce for testing */ +int fscrypt_ioctl_get_nonce(struct file *filp, void __user *arg) +{ + struct inode *inode = file_inode(filp); + union fscrypt_context ctx; + int ret; + + ret = inode->i_sb->s_cop->get_context(inode, &ctx, sizeof(ctx)); + if (ret < 0) + return ret; + if (!fscrypt_context_is_valid(&ctx, ret)) + return -EINVAL; + if (copy_to_user(arg, fscrypt_context_nonce(&ctx), + FSCRYPT_FILE_NONCE_SIZE)) + return -EFAULT; + return 0; +} +EXPORT_SYMBOL_GPL(fscrypt_ioctl_get_nonce); + /** * fscrypt_has_permitted_context() - is a file's encryption policy permitted * within its directory? @@ -573,7 +641,7 @@ int fscrypt_inherit_context(struct inode *parent, struct inode *child, if (res < 0) return res; - ci = READ_ONCE(parent->i_crypt_info); + ci = fscrypt_get_info(parent); if (ci == NULL) return -ENOKEY; @@ -586,3 +654,127 @@ int fscrypt_inherit_context(struct inode *parent, struct inode *child, return preload ? fscrypt_get_encryption_info(child): 0; } EXPORT_SYMBOL(fscrypt_inherit_context); + +/** + * fscrypt_set_test_dummy_encryption() - handle '-o test_dummy_encryption' + * @sb: the filesystem on which test_dummy_encryption is being specified + * @arg: the argument to the test_dummy_encryption option. + * If no argument was specified, then @arg->from == NULL. + * @dummy_ctx: the filesystem's current dummy context (input/output, see below) + * + * Handle the test_dummy_encryption mount option by creating a dummy encryption + * context, saving it in @dummy_ctx, and adding the corresponding dummy + * encryption key to the filesystem. If the @dummy_ctx is already set, then + * instead validate that it matches @arg. Don't support changing it via + * remount, as that is difficult to do safely. + * + * The reason we use an fscrypt_context rather than an fscrypt_policy is because + * we mustn't generate a new nonce each time we access a dummy-encrypted + * directory, as that would change the way filenames are encrypted. + * + * Return: 0 on success (dummy context set, or the same context is already set); + * -EEXIST if a different dummy context is already set; + * or another -errno value. + */ +int fscrypt_set_test_dummy_encryption(struct super_block *sb, + const substring_t *arg, + struct fscrypt_dummy_context *dummy_ctx) +{ + const char *argstr = "v2"; + const char *argstr_to_free = NULL; + struct fscrypt_key_specifier key_spec = { 0 }; + int version; + union fscrypt_context *ctx = NULL; + int err; + + if (arg->from) { + argstr = argstr_to_free = match_strdup(arg); + if (!argstr) + return -ENOMEM; + } + + if (!strcmp(argstr, "v1")) { + version = FSCRYPT_CONTEXT_V1; + key_spec.type = FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR; + memset(key_spec.u.descriptor, 0x42, + FSCRYPT_KEY_DESCRIPTOR_SIZE); + } else if (!strcmp(argstr, "v2")) { + version = FSCRYPT_CONTEXT_V2; + key_spec.type = FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER; + /* key_spec.u.identifier gets filled in when adding the key */ + } else { + err = -EINVAL; + goto out; + } + + if (dummy_ctx->ctx) { + /* + * Note: if we ever make test_dummy_encryption support + * specifying other encryption settings, such as the encryption + * modes, we'll need to compare those settings here. + */ + if (dummy_ctx->ctx->version == version) + err = 0; + else + err = -EEXIST; + goto out; + } + + ctx = kzalloc(sizeof(*ctx), GFP_KERNEL); + if (!ctx) { + err = -ENOMEM; + goto out; + } + + err = fscrypt_add_test_dummy_key(sb, &key_spec); + if (err) + goto out; + + ctx->version = version; + switch (ctx->version) { + case FSCRYPT_CONTEXT_V1: + ctx->v1.contents_encryption_mode = FSCRYPT_MODE_AES_256_XTS; + ctx->v1.filenames_encryption_mode = FSCRYPT_MODE_AES_256_CTS; + memcpy(ctx->v1.master_key_descriptor, key_spec.u.descriptor, + FSCRYPT_KEY_DESCRIPTOR_SIZE); + break; + case FSCRYPT_CONTEXT_V2: + ctx->v2.contents_encryption_mode = FSCRYPT_MODE_AES_256_XTS; + ctx->v2.filenames_encryption_mode = FSCRYPT_MODE_AES_256_CTS; + memcpy(ctx->v2.master_key_identifier, key_spec.u.identifier, + FSCRYPT_KEY_IDENTIFIER_SIZE); + break; + default: + WARN_ON(1); + err = -EINVAL; + goto out; + } + dummy_ctx->ctx = ctx; + ctx = NULL; + err = 0; +out: + kfree(ctx); + kfree(argstr_to_free); + return err; +} +EXPORT_SYMBOL_GPL(fscrypt_set_test_dummy_encryption); + +/** + * fscrypt_show_test_dummy_encryption() - show '-o test_dummy_encryption' + * @seq: the seq_file to print the option to + * @sep: the separator character to use + * @sb: the filesystem whose options are being shown + * + * Show the test_dummy_encryption mount option, if it was specified. + * This is mainly used for /proc/mounts. + */ +void fscrypt_show_test_dummy_encryption(struct seq_file *seq, char sep, + struct super_block *sb) +{ + const union fscrypt_context *ctx = fscrypt_get_dummy_context(sb); + + if (!ctx) + return; + seq_printf(seq, "%ctest_dummy_encryption=v%d", sep, ctx->version); +} +EXPORT_SYMBOL_GPL(fscrypt_show_test_dummy_encryption); |