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| author | Dmitry Kasatkin <dmitry.kasatkin@nokia.com> | 2011-05-06 12:34:14 +0400 |
|---|---|---|
| committer | Mimi Zohar <zohar@linux.vnet.ibm.com> | 2011-07-18 20:29:48 +0400 |
| commit | 6d38ca01c0c2d6c2e46ec1984db9ada6bad6ca26 (patch) | |
| tree | 6084a84cd87d18c261d62dc816d48335ce602447 /security/integrity | |
| parent | 2960e6cb5f7c662b8edb6b0d2edc72095b4f5672 (diff) | |
| download | linux-6d38ca01c0c2d6c2e46ec1984db9ada6bad6ca26.tar.xz | |
evm: evm_verify_hmac must not return INTEGRITY_UNKNOWN
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>
Diffstat (limited to 'security/integrity')
| -rw-r--r-- | security/integrity/evm/evm_main.c | 11 |
1 files changed, 5 insertions, 6 deletions
diff --git a/security/integrity/evm/evm_main.c b/security/integrity/evm/evm_main.c index 0fa8261c3655..bfe44dff61bb 100644 --- a/security/integrity/evm/evm_main.c +++ b/security/integrity/evm/evm_main.c @@ -56,13 +56,15 @@ static enum integrity_status evm_verify_hmac(struct dentry *dentry, struct evm_ima_xattr_data xattr_data; int rc; - if (iint->hmac_status != INTEGRITY_UNKNOWN) + if (iint->hmac_status == INTEGRITY_PASS) return iint->hmac_status; + /* if status is not PASS, try to check again - against -ENOMEM */ + rc = evm_calc_hmac(dentry, xattr_name, xattr_value, xattr_value_len, xattr_data.digest); if (rc < 0) - return INTEGRITY_UNKNOWN; + goto err_out; xattr_data.type = EVM_XATTR_HMAC; rc = vfs_xattr_cmp(dentry, XATTR_NAME_EVM, (u8 *)&xattr_data, @@ -77,11 +79,8 @@ err_out: case -ENODATA: /* file not labelled */ iint->hmac_status = INTEGRITY_NOLABEL; break; - case -EINVAL: - iint->hmac_status = INTEGRITY_FAIL; - break; default: - iint->hmac_status = INTEGRITY_UNKNOWN; + iint->hmac_status = INTEGRITY_FAIL; } return iint->hmac_status; } |