[PATCH] ima: Fix sigv3 signature handling for EVM_IMA_XATTR_DIGSIG

[Kamlesh Kumar <kamlesh0hrs@gmail.com>]

ima_get_hash_algo() only recognizes version 2 signatures when the xattr
type is EVM_IMA_XATTR_DIGSIG. Since sigv3 signatures also use
EVM_IMA_XATTR_DIGSIG as the xattr type, version 3 must be accepted as
well to correctly determine the hash algorithm.

Additionally, ima_validate_rule() does not include IMA_SIGV3_REQUIRED in
the allowed flags bitmask for MODULE_CHECK, KEXEC_KERNEL_CHECK, and
KEXEC_INITRAMFS_CHECK hook functions. As a result, policy rules with
"appraise_type=sigv3" are rejected for these functions.

Add version 3 to the accepted versions in ima_get_hash_algo() for
EVM_IMA_XATTR_DIGSIG, and add IMA_SIGV3_REQUIRED to the allowed flags
for MODULE_CHECK, KEXEC_KERNEL_CHECK, and KEXEC_INITRAMFS_CHECK in
ima_validate_rule().

Signed-off-by: Kamlesh Kumar <kam@juniper.net>
---
 security/integrity/ima/ima_appraise.c | 5 +++--
 security/integrity/ima/ima_policy.c   | 3 ++-
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c
index de963b9f3634..2dd231567710 100644
--- a/security/integrity/ima/ima_appraise.c
+++ b/security/integrity/ima/ima_appraise.c
@@ -195,8 +195,9 @@ enum hash_algo ima_get_hash_algo(const struct evm_ima_xattr_data *xattr_value,
 		return sig->hash_algo;
 	case EVM_IMA_XATTR_DIGSIG:
 		sig = (typeof(sig))xattr_value;
-		if (sig->version != 2 || xattr_len <= sizeof(*sig)
-		    || sig->hash_algo >= HASH_ALGO__LAST)
+		if ((sig->version != 2 && sig->version != 3) ||
+		    xattr_len <= sizeof(*sig) ||
+		    sig->hash_algo >= HASH_ALGO__LAST)
 			return ima_hash_algo;
 		return sig->hash_algo;
 	case IMA_XATTR_DIGEST_NG:
diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index f7f940a76922..b1c010e8eb13 100644
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c
@@ -1313,7 +1313,8 @@ static bool ima_validate_rule(struct ima_rule_entry *entry)
 				     IMA_GID | IMA_EGID |
 				     IMA_FGROUP | IMA_DIGSIG_REQUIRED |
 				     IMA_PERMIT_DIRECTIO | IMA_MODSIG_ALLOWED |
-				     IMA_CHECK_BLACKLIST | IMA_VALIDATE_ALGOS))
+				     IMA_CHECK_BLACKLIST | IMA_VALIDATE_ALGOS |
+				     IMA_SIGV3_REQUIRED))
 			return false;
 
 		break;

base-commit: 82bbd447199ff1441031d2eaf9afe041550cf525
-- 
2.34.1