diff options
| -rw-r--r-- | security/integrity/ima/ima_appraise.c | 141 |
1 files changed, 81 insertions, 60 deletions
diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c index 89b83194d1dc..d3298045737f 100644 --- a/security/integrity/ima/ima_appraise.c +++ b/security/integrity/ima/ima_appraise.c @@ -200,6 +200,83 @@ int ima_read_xattr(struct dentry *dentry, } /* + * xattr_verify - verify xattr digest or signature + * + * Verify whether the hash or signature matches the file contents. + * + * Return 0 on success, error code otherwise. + */ +static int xattr_verify(enum ima_hooks func, struct integrity_iint_cache *iint, + struct evm_ima_xattr_data *xattr_value, int xattr_len, + enum integrity_status *status, const char **cause) +{ + int rc = -EINVAL, hash_start = 0; + + switch (xattr_value->type) { + case IMA_XATTR_DIGEST_NG: + /* first byte contains algorithm id */ + hash_start = 1; + /* fall through */ + case IMA_XATTR_DIGEST: + if (iint->flags & IMA_DIGSIG_REQUIRED) { + *cause = "IMA-signature-required"; + *status = INTEGRITY_FAIL; + break; + } + clear_bit(IMA_DIGSIG, &iint->atomic_flags); + if (xattr_len - sizeof(xattr_value->type) - hash_start >= + iint->ima_hash->length) + /* + * xattr length may be longer. md5 hash in previous + * version occupied 20 bytes in xattr, instead of 16 + */ + rc = memcmp(&xattr_value->data[hash_start], + iint->ima_hash->digest, + iint->ima_hash->length); + else + rc = -EINVAL; + if (rc) { + *cause = "invalid-hash"; + *status = INTEGRITY_FAIL; + break; + } + *status = INTEGRITY_PASS; + break; + case EVM_IMA_XATTR_DIGSIG: + set_bit(IMA_DIGSIG, &iint->atomic_flags); + rc = integrity_digsig_verify(INTEGRITY_KEYRING_IMA, + (const char *)xattr_value, + xattr_len, + iint->ima_hash->digest, + iint->ima_hash->length); + if (rc == -EOPNOTSUPP) { + *status = INTEGRITY_UNKNOWN; + break; + } + if (IS_ENABLED(CONFIG_INTEGRITY_PLATFORM_KEYRING) && rc && + func == KEXEC_KERNEL_CHECK) + rc = integrity_digsig_verify(INTEGRITY_KEYRING_PLATFORM, + (const char *)xattr_value, + xattr_len, + iint->ima_hash->digest, + iint->ima_hash->length); + if (rc) { + *cause = "invalid-signature"; + *status = INTEGRITY_FAIL; + } else { + *status = INTEGRITY_PASS; + } + break; + default: + *status = INTEGRITY_UNKNOWN; + *cause = "unknown-ima-data"; + break; + } + + return rc; +} + +/* * ima_appraise_measurement - appraise file measurement * * Call evm_verifyxattr() to verify the integrity of 'security.ima'. @@ -218,7 +295,7 @@ int ima_appraise_measurement(enum ima_hooks func, struct dentry *dentry = file_dentry(file); struct inode *inode = d_backing_inode(dentry); enum integrity_status status = INTEGRITY_UNKNOWN; - int rc = xattr_len, hash_start = 0; + int rc = xattr_len; if (!(inode->i_opflags & IOP_XATTR)) return INTEGRITY_UNKNOWN; @@ -256,65 +333,9 @@ int ima_appraise_measurement(enum ima_hooks func, WARN_ONCE(true, "Unexpected integrity status %d\n", status); } - switch (xattr_value->type) { - case IMA_XATTR_DIGEST_NG: - /* first byte contains algorithm id */ - hash_start = 1; - /* fall through */ - case IMA_XATTR_DIGEST: - if (iint->flags & IMA_DIGSIG_REQUIRED) { - cause = "IMA-signature-required"; - status = INTEGRITY_FAIL; - break; - } - clear_bit(IMA_DIGSIG, &iint->atomic_flags); - if (xattr_len - sizeof(xattr_value->type) - hash_start >= - iint->ima_hash->length) - /* xattr length may be longer. md5 hash in previous - version occupied 20 bytes in xattr, instead of 16 - */ - rc = memcmp(&xattr_value->data[hash_start], - iint->ima_hash->digest, - iint->ima_hash->length); - else - rc = -EINVAL; - if (rc) { - cause = "invalid-hash"; - status = INTEGRITY_FAIL; - break; - } - status = INTEGRITY_PASS; - break; - case EVM_IMA_XATTR_DIGSIG: - set_bit(IMA_DIGSIG, &iint->atomic_flags); - rc = integrity_digsig_verify(INTEGRITY_KEYRING_IMA, - (const char *)xattr_value, - xattr_len, - iint->ima_hash->digest, - iint->ima_hash->length); - if (rc == -EOPNOTSUPP) { - status = INTEGRITY_UNKNOWN; - break; - } - if (IS_ENABLED(CONFIG_INTEGRITY_PLATFORM_KEYRING) && rc && - func == KEXEC_KERNEL_CHECK) - rc = integrity_digsig_verify(INTEGRITY_KEYRING_PLATFORM, - (const char *)xattr_value, - xattr_len, - iint->ima_hash->digest, - iint->ima_hash->length); - if (rc) { - cause = "invalid-signature"; - status = INTEGRITY_FAIL; - } else { - status = INTEGRITY_PASS; - } - break; - default: - status = INTEGRITY_UNKNOWN; - cause = "unknown-ima-data"; - break; - } + if (xattr_value) + rc = xattr_verify(func, iint, xattr_value, xattr_len, &status, + &cause); out: /* |