4.9-stable review patch. If anyone has any objections, please let me know.
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From: Eric Biggers ebiggers@google.com
[ 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: 757932e6da6d ("PKCS#7: Handle PKCS#7 messages that contain no X.509 certs") Signed-off-by: Eric Biggers ebiggers@google.com Signed-off-by: David Howells dhowells@redhat.com Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- crypto/asymmetric_keys/pkcs7_trust.c | 1 + 1 file changed, 1 insertion(+)
--- a/crypto/asymmetric_keys/pkcs7_trust.c +++ b/crypto/asymmetric_keys/pkcs7_trust.c @@ -106,6 +106,7 @@ static int pkcs7_validate_trust_one(stru 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)