Messages in this thread Patch in this message | | | Subject | [PATCH] X.509: Fix determination of self-signedness | From | David Howells <> | Date | Fri, 18 Dec 2015 00:03:02 +0000 |
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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 <dhowells@redhat.com> cc: David Woodhouse <David.Woodhouse@intel.com> ---
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;
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