Re: [PATCH] X.509: Fix determination of self-signedness
On Thu, Dec 17, 2015 at 7:03 PM, David Howellswrote: > Fix determination of whether an X.509 certificate is self-signed or not. > > It is currently assumed that a cert is self-signed if has no > authorityKeyIdentifier or the authorityKeyIdentifier matches the > subjectKeyIdentifier. However, it is possible to encounter a certificate > that has neither AKID not SKID but is not self-signed. > > This symptoms of this show up as an attempt to load a certificate failing > with -ERANGE or -EBADMSG, produced from the RSA module when the result of > calculating "m = s^e mod n" is checked. > > To fix this, don't check to see if a certificate is self-signed if the > Issuer and Subject names differ. > > Signed-off-by: David Howells > cc: David Woodhouse Should this also be Cc'd to stable? josh > --- > > crypto/asymmetric_keys/x509_public_key.c | 11 --- > 1 file changed, 8 insertions(+), 3 deletions(-) > > diff --git a/crypto/asymmetric_keys/x509_public_key.c > b/crypto/asymmetric_keys/x509_public_key.c > index 2a44b3752471..6236e7996f19 100644 > --- a/crypto/asymmetric_keys/x509_public_key.c > +++ b/crypto/asymmetric_keys/x509_public_key.c > @@ -313,9 +313,14 @@ static int x509_key_preparse(struct > key_preparsed_payload *prep) > 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)) { > + if ((!cert->akid_skid && !cert->akid_id)) { > + if (cert->raw_issuer_size == cert->raw_subject_size && > + memcmp(cert->raw_issuer, cert->raw_subject, > + cert->raw_subject_size) == 0) > + goto self_signed; > + } else if (asymmetric_key_id_same(cert->skid, cert->akid_skid) || > + asymmetric_key_id_same(cert->id, cert->akid_id)) { > +self_signed: > ret = x509_check_signature(cert->pub, cert); /* self-signed */ > if (ret < 0) > goto error_free_cert; > -- 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
Re: [PATCH] X.509: Fix determination of self-signedness
Josh Boyerwrote: > Should this also be Cc'd to stable? Argh. Probably. David -- 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
[PATCH] X.509: Fix determination of self-signedness
Fix determination of whether an X.509 certificate is self-signed or not. It is currently assumed that a cert is self-signed if has no authorityKeyIdentifier or the authorityKeyIdentifier matches the subjectKeyIdentifier. However, it is possible to encounter a certificate that has neither AKID not SKID but is not self-signed. This symptoms of this show up as an attempt to load a certificate failing with -ERANGE or -EBADMSG, produced from the RSA module when the result of calculating "m = s^e mod n" is checked. To fix this, don't check to see if a certificate is self-signed if the Issuer and Subject names differ. Signed-off-by: David Howellscc: David Woodhouse --- crypto/asymmetric_keys/x509_public_key.c | 11 --- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/crypto/asymmetric_keys/x509_public_key.c b/crypto/asymmetric_keys/x509_public_key.c index 2a44b3752471..6236e7996f19 100644 --- a/crypto/asymmetric_keys/x509_public_key.c +++ b/crypto/asymmetric_keys/x509_public_key.c @@ -313,9 +313,14 @@ static int x509_key_preparse(struct key_preparsed_payload *prep) 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)) { + if ((!cert->akid_skid && !cert->akid_id)) { + if (cert->raw_issuer_size == cert->raw_subject_size && + memcmp(cert->raw_issuer, cert->raw_subject, + cert->raw_subject_size) == 0) + goto self_signed; + } else if (asymmetric_key_id_same(cert->skid, cert->akid_skid) || + asymmetric_key_id_same(cert->id, cert->akid_id)) { +self_signed: ret = x509_check_signature(cert->pub, cert); /* self-signed */ if (ret < 0) goto error_free_cert; -- 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