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Subject[PATCH 4.15 14/64] PKCS#7: fix certificate blacklisting
Date
4.15-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Eric Biggers <ebiggers@google.com>

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.

Fixes: 03bb79315ddc ("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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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

--- a/crypto/asymmetric_keys/pkcs7_verify.c
+++ b/crypto/asymmetric_keys/pkcs7_verify.c
@@ -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;

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