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Commit 4d7388a1 authored by Eric Biggers's avatar Eric Biggers Committed by Greg Kroah-Hartman
Browse files

PKCS#7: fix direct verification of SignerInfo signature 



[ Upstream commit 6459ae386699a5fe0dc52cf30255f75274fa43a4 ]

If none of the certificates in a SignerInfo's certificate chain match a
trusted key, nor is the last certificate signed by a trusted key, then
pkcs7_validate_trust_one() tries to check whether the SignerInfo's
signature was made directly by a trusted key.  But, it actually fails to
set the 'sig' variable correctly, so it actually verifies the last
signature seen.  That will only be the SignerInfo's signature if the
certificate chain is empty; otherwise it will actually be the last
certificate's signature.

This is not by itself a security problem, since verifying any of the
certificates in the chain should be sufficient to verify the SignerInfo.
Still, it's not working as intended so it should be fixed.

Fix it by setting 'sig' correctly for the direct verification case.

Fixes: 757932e6 ("PKCS#7: Handle PKCS#7 messages that contain no X.509 certs")
Signed-off-by: default avatarEric Biggers <ebiggers@google.com>
Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
Signed-off-by: default avatarSasha Levin <alexander.levin@microsoft.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent f18fb145

crypto/asymmetric_keys/pkcs7_trust.c

+1 −0
Original line number Diff line number Diff line
@@ -106,6 +106,7 @@ static int pkcs7_validate_trust_one(struct pkcs7_message *pkcs7, 
		pr_devel("sinfo %u: Direct signer is key %x\n",

			 sinfo->index, key_serial(key));

		x509 = NULL;

		sig = sinfo->sig;

		goto matched;

	}

	if (PTR_ERR(key) != -ENOKEY)