On Tue, 2016-01-05 at 15:47 +0000, David Howells wrote: > If a certificate is self-signed, don't bother checking the validity of the > signature. The cert cannot be checked by validation against the next one > in the chain as this is the root of the chain. Trust for this certificate > can only be determined by whether we obtained it from a trusted location > (ie. it was built into the kernel at compile time). > > This also fixes a bug whereby certificates were being assumed to be > self-signed if they had neither AKID nor SKID, the symptoms of which show > up as an attempt to load a certificate failing with -ERANGE or -EBADMSG. > This is produced from the RSA module when the result of calculating "m = > s^e mod n" is checked. > > Signed-off-by: David Howells <dhowe...@redhat.com> > cc: David Woodhouse <david.woodho...@intel.com> > cc: Mimi Zohar <zo...@linux.vnet.ibm.com> > --- > > crypto/asymmetric_keys/x509_public_key.c | 25 ++++++++++++++++--------- > 1 file changed, 16 insertions(+), 9 deletions(-) > > diff --git a/crypto/asymmetric_keys/x509_public_key.c > b/crypto/asymmetric_keys/x509_public_key.c > index 2a44b3752471..26e1937af7f4 100644 > --- a/crypto/asymmetric_keys/x509_public_key.c > +++ b/crypto/asymmetric_keys/x509_public_key.c > @@ -255,6 +255,9 @@ static int x509_validate_trust(struct x509_certificate > *cert, > struct key *key; > int ret = 1; > > + if (!cert->akid_id || !cert->akid_skid) > + return 1; > + > if (!trust_keyring) > return -EOPNOTSUPP; > > @@ -312,17 +315,21 @@ static int x509_key_preparse(struct > key_preparsed_payload *prep) > cert->pub->algo = pkey_algo[cert->pub->pkey_algo]; > cert->pub->id_type = PKEY_ID_X509; > > - /* Check the signature on the key if it appears to be self-signed */ > - if ((!cert->akid_skid && !cert->akid_id) || > - asymmetric_key_id_same(cert->skid, cert->akid_skid) || > - asymmetric_key_id_same(cert->id, cert->akid_id)) { > - ret = x509_check_signature(cert->pub, cert); /* self-signed */ > - if (ret < 0) > - goto error_free_cert; > - } else if (!prep->trusted) { > + /* See if we can derive the trustability of this certificate. > + * > + * When it comes to self-signed certificates, we cannot evaluate > + * trustedness except by the fact that we obtained it from a trusted > + * location. So we just rely on x509_validate_trust() failing in this > + * case. > + * > + * Note that there's a possibility of a self-signed cert matching a > + * cert that we have (most likely a duplicate that we already trust) - > + * in which case it will be marked trusted. > + */ > + if (!prep->trusted) { > ret = x509_validate_trust(cert, get_system_trusted_keyring()); > if (!ret) > - prep->trusted = 1; > + prep->trusted = true; > }
You're missing Petko's patch: 41c89b6 IMA: create machine owner and blacklist keyrings Mimi > > /* Propose a description */ > -- To unsubscribe from this list: send the line "unsubscribe linux-security-module" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html