Patch "PKCS#7: fix certificate blacklisting" has been added to the 4.15-stable tree

This is a note to let you know that I've just added the patch titled

PKCS#7: fix certificate blacklisting

to the 4.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
pkcs-7-fix-certificate-blacklisting.patch
and it can be found in the queue-4.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Eric Biggers <[email protected]>
Date: Thu, 22 Feb 2018 14:38:33 +0000
Subject: PKCS#7: fix certificate blacklisting

From: Eric Biggers <[email protected]>

commit 29f4a67c17e19314b7d74b8569be935e6c7edf50 upstream.

If there is a blacklisted certificate in a SignerInfo's certificate chain, then pkcs7_verify_sig_chain() sets sinfo->blacklisted and returns
0. But, pkcs7_verify() fails to handle this case appropriately, as it actually continues on to the line 'actual_ret = 0;', indicating that the SignerInfo has passed verification. Consequently, PKCS#7 signature verification ignores the certificate blacklist.

Fix this by not considering blacklisted SignerInfos to have passed verification.

Also fix the function comment with regards to when 0 is returned.

---
 crypto/asymmetric_keys/pkcs7_verify.c |   10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

@@ -366,8 +366,7 @@ static int pkcs7_verify_one(struct pkcs7
  *
  *  (*) -EBADMSG if some part of the message was invalid, or:
  *
- *  (*) 0 if no signature chains were found to be blacklisted or to contain
- *	unsupported crypto, or:
+ *  (*) 0 if a signature chain passed verification, or:
  *
  *  (*) -EKEYREJECTED if a blacklisted key was encountered, or:
  *

@@ -423,8 +422,11 @@ int pkcs7_verify(struct pkcs7_message *p
 
 	for (sinfo = pkcs7->signed_infos; sinfo; sinfo = sinfo->next) {
 		ret = pkcs7_verify_one(pkcs7, sinfo);
-		if (sinfo->blacklisted && actual_ret == -ENOPKG)
-			actual_ret = -EKEYREJECTED;
+		if (sinfo->blacklisted) {
+			if (actual_ret == -ENOPKG)
+				actual_ret = -EKEYREJECTED;
+			continue;
+		}
 		if (ret < 0) {
 			if (ret == -ENOPKG) {
 				sinfo->unsupported_crypto = true;

Patches currently in stable-queue which might be from [email protected] are

queue-4.15/pkcs-7-fix-certificate-blacklisting.patch queue-4.15/x.509-fix-null-dereference-when-restricting-key-with-unsupported_sig.patch queue-4.15/x.509-fix-bug_on-when-hash-algorithm-is-unsupported.patch queue-4.15/pkcs-7-fix-certificate-chain-verification.patch