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| author | Seth Forshee <seth.forshee@canonical.com> | 2016-08-01 08:19:10 -0500 |
|---|---|---|
| committer | Mimi Zohar <zohar@linux.vnet.ibm.com> | 2016-11-13 22:50:11 -0500 |
| commit | b4bfec7f4a86424b114f94f41c4e1841ec102df3 (patch) | |
| tree | 9f4a668c3d28ef3de0743d3dda285829b38a85a3 /security | |
| parent | 5465d02a4970990d8ec692c7539af5fdde95e613 (diff) | |
| download | lwn-b4bfec7f4a86424b114f94f41c4e1841ec102df3.tar.gz lwn-b4bfec7f4a86424b114f94f41c4e1841ec102df3.zip | |
security/integrity: Harden against malformed xattrs
In general the handling of IMA/EVM xattrs is good, but I found
a few locations where either the xattr size or the value of the
type field in the xattr are not checked. Add a few simple checks
to these locations to prevent malformed or malicious xattrs from
causing problems.
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Diffstat (limited to 'security')
| -rw-r--r-- | security/integrity/digsig.c | 2 | ||||
| -rw-r--r-- | security/integrity/evm/evm_main.c | 4 | ||||
| -rw-r--r-- | security/integrity/ima/ima_appraise.c | 5 |
3 files changed, 9 insertions, 2 deletions
diff --git a/security/integrity/digsig.c b/security/integrity/digsig.c index 4304372b323f..106e855e2d9d 100644 --- a/security/integrity/digsig.c +++ b/security/integrity/digsig.c @@ -51,7 +51,7 @@ static bool init_keyring __initdata; int integrity_digsig_verify(const unsigned int id, const char *sig, int siglen, const char *digest, int digestlen) { - if (id >= INTEGRITY_KEYRING_MAX) + if (id >= INTEGRITY_KEYRING_MAX || siglen < 2) return -EINVAL; if (!keyring[id]) { diff --git a/security/integrity/evm/evm_main.c b/security/integrity/evm/evm_main.c index ba8615576d4d..e2ed498c0f5f 100644 --- a/security/integrity/evm/evm_main.c +++ b/security/integrity/evm/evm_main.c @@ -145,6 +145,10 @@ static enum integrity_status evm_verify_hmac(struct dentry *dentry, /* check value type */ switch (xattr_data->type) { case EVM_XATTR_HMAC: + if (xattr_len != sizeof(struct evm_ima_xattr_data)) { + evm_status = INTEGRITY_FAIL; + goto out; + } rc = evm_calc_hmac(dentry, xattr_name, xattr_value, xattr_value_len, calc.digest); if (rc) diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c index a705598ced5f..1fd9539a969d 100644 --- a/security/integrity/ima/ima_appraise.c +++ b/security/integrity/ima/ima_appraise.c @@ -130,6 +130,7 @@ enum hash_algo ima_get_hash_algo(struct evm_ima_xattr_data *xattr_value, int xattr_len) { struct signature_v2_hdr *sig; + enum hash_algo ret; if (!xattr_value || xattr_len < 2) /* return default hash algo */ @@ -143,7 +144,9 @@ enum hash_algo ima_get_hash_algo(struct evm_ima_xattr_data *xattr_value, return sig->hash_algo; break; case IMA_XATTR_DIGEST_NG: - return xattr_value->digest[0]; + ret = xattr_value->digest[0]; + if (ret < HASH_ALGO__LAST) + return ret; break; case IMA_XATTR_DIGEST: /* this is for backward compatibility */ |