2017-11-27 07:19:47

by Eric Biggers

Subject: [PATCH] pkcs7: fix check for self-signed certificate

From: Eric Biggers <[email protected]>

pkcs7_validate_trust_one() used 'x509->next == x509' to identify a
self-signed certificate. That's wrong; ->next is simply the link in the
linked list of certificates in the PKCS#7 message. It should be
checking ->signer instead. Fix it.

Fortunately this didn't actually matter because when we re-visited
'x509' on the next iteration via 'x509->signer', it was already seen and
not verified, so we returned -ENOKEY anyway.

Signed-off-by: Eric Biggers <[email protected]>
---
crypto/asymmetric_keys/pkcs7_trust.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/crypto/asymmetric_keys/pkcs7_trust.c b/crypto/asymmetric_keys/pkcs7_trust.c
index f6a009d88a33..1f4e25f10049 100644
--- a/crypto/asymmetric_keys/pkcs7_trust.c
+++ b/crypto/asymmetric_keys/pkcs7_trust.c
@@ -69,7 +69,7 @@ static int pkcs7_validate_trust_one(struct pkcs7_message *pkcs7,
/* Self-signed certificates form roots of their own, and if we
* don't know them, then we can't accept them.
*/
- if (x509->next == x509) {
+ if (x509->signer == x509) {
kleave(" = -ENOKEY [unknown self-signed]");
return -ENOKEY;
}
--
2.15.0

2017-11-27 09:55:08

by James Morris

Subject: Re: [PATCH] pkcs7: fix check for self-signed certificate

On Sun, 26 Nov 2017, Eric Biggers wrote:

> From: Eric Biggers <[email protected]>
>
> pkcs7_validate_trust_one() used 'x509->next == x509' to identify a
> self-signed certificate. That's wrong; ->next is simply the link in the
> linked list of certificates in the PKCS#7 message. It should be
> checking ->signer instead. Fix it.
>
> Fortunately this didn't actually matter because when we re-visited
> 'x509' on the next iteration via 'x509->signer', it was already seen and
> not verified, so we returned -ENOKEY anyway.
>
> Signed-off-by: Eric Biggers <[email protected]>
> ---
> crypto/asymmetric_keys/pkcs7_trust.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/crypto/asymmetric_keys/pkcs7_trust.c b/crypto/asymmetric_keys/pkcs7_trust.c
> index f6a009d88a33..1f4e25f10049 100644
> --- a/crypto/asymmetric_keys/pkcs7_trust.c
> +++ b/crypto/asymmetric_keys/pkcs7_trust.c
> @@ -69,7 +69,7 @@ static int pkcs7_validate_trust_one(struct pkcs7_message *pkcs7,
> /* Self-signed certificates form roots of their own, and if we
> * don't know them, then we can't accept them.
> */
> - if (x509->next == x509) {
> + if (x509->signer == x509) {
> kleave(" = -ENOKEY [unknown self-signed]");
> return -ENOKEY;
> }
> --


Reviewed-by: James Morris <[email protected]>

--
James Morris
<[email protected]>