Commit 29f4a67c authored Feb 22, 2018 by Eric Biggers Committed by David Howells Feb 22, 2018

PKCS#7: fix certificate blacklisting



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.

Fixes: 03bb7931 ("PKCS#7: Handle blacklisted certificates")
Cc: <stable@vger.kernel.org> # v4.12+
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>

parent 971b42c0

crypto/asymmetric_keys/pkcs7_verify.c

+6 −4

Original line number	Diff line number	Diff line
		@@ -366,8 +366,7 @@ static int pkcs7_verify_one(struct pkcs7_message *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 *pkcs7,

		for (sinfo = pkcs7->signed_infos; sinfo; sinfo = sinfo->next) {
		ret = pkcs7_verify_one(pkcs7, sinfo);
		if (sinfo->blacklisted && actual_ret == -ENOPKG)
		if (sinfo->blacklisted) {
		if (actual_ret == -ENOPKG)
		actual_ret = -EKEYREJECTED;
		continue;
		}
		if (ret < 0) {
		if (ret == -ENOPKG) {
		sinfo->unsupported_crypto = true;