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PKCS#7: fix certificate blacklisting

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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: 03bb79315d ("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>
This commit is contained in:
Eric Biggers 2018-02-22 14:38:33 +00:00 committed by David Howells
parent 971b42c038
commit 29f4a67c17
1 changed files with 6 additions and 4 deletions
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10
crypto/asymmetric_keys/pkcs7_verify.c
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@ -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)
actual_ret = -EKEYREJECTED;
if (sinfo->blacklisted) {
if (actual_ret == -ENOPKG)
actual_ret = -EKEYREJECTED;
continue;
}
if (ret < 0) {
if (ret == -ENOPKG) {
sinfo->unsupported_crypto = true;