| Message ID | 88da0c24-385c-64a9-6d56-36696d433bc7@maciej.szmigiero.name (mailing list archive) |
|---|---|
| State | Not Applicable |
| Delegated to: | Herbert Xu |
| Headers | show |
Maciej S. Szmigiero <mail@maciej.szmigiero.name> wrote:
> + if (!strcmp(ctx->cert->sig->pkey_algo, "rsa")) {
I'm going to change this to '== 0' rather than '!'.
David
On 07.03.2018 16:44, David Howells wrote: > Maciej S. Szmigiero <mail@maciej.szmigiero.name> wrote: > >> + if (!strcmp(ctx->cert->sig->pkey_algo, "rsa")) { > > I'm going to change this to '== 0' rather than '!'. No problem. > David > Thanks, Maciej
On 07.03.2018 18:56, Maciej S. Szmigiero wrote: > On 07.03.2018 16:44, David Howells wrote: >> Maciej S. Szmigiero <mail@maciej.szmigiero.name> wrote: >> >>> + if (!strcmp(ctx->cert->sig->pkey_algo, "rsa")) { >> >> I'm going to change this to '== 0' rather than '!'. > > No problem. I cannot find this patch in any tree that I have looked at. Are you going to pick it up later or am I not looking at the right place? Thanks, Maciej
diff --git a/crypto/asymmetric_keys/x509_cert_parser.c b/crypto/asymmetric_keys/x509_cert_parser.c index ce2df8c9c583..88c26a4538ae 100644 --- a/crypto/asymmetric_keys/x509_cert_parser.c +++ b/crypto/asymmetric_keys/x509_cert_parser.c @@ -249,6 +249,15 @@ int x509_note_signature(void *context, size_t hdrlen, return -EINVAL; } + if (!strcmp(ctx->cert->sig->pkey_algo, "rsa")) { + /* Discard the BIT STRING metadata */ + if (vlen < 1 || *(const u8 *)value != 0) + return -EBADMSG; + + value++; + vlen--; + } + ctx->cert->raw_sig = value; ctx->cert->raw_sig_size = vlen; return 0;
The signatureValue field of a X.509 certificate is encoded as a BIT STRING. For RSA signatures this BIT STRING is of so-called primitive subtype, which contains a u8 prefix indicating a count of unused bits in the encoding. We have to strip this prefix from signature data, just as we already do for key data in x509_extract_key_data() function. This wasn't noticed earlier because this prefix byte is zero for RSA key sizes divisible by 8. Since BIT STRING is a big-endian encoding adding zero prefixes has no bearing on its value. The signature length, however was incorrect, which is a problem for RSA implementations that need it to be exactly correct (like AMD CCP). Signed-off-by: Maciej S. Szmigiero <mail@maciej.szmigiero.name> Fixes: c26fd69fa009 ("X.509: Add a crypto key parser for binary (DER) X.509 certificates") Cc: stable@vger.kernel.org --- This is a resend without changes of a patch that was previously submitted in one series with CCP driver changes since this particular patch should go through the security (rather than crypto) tree. crypto/asymmetric_keys/x509_cert_parser.c | 9 +++++++++ 1 file changed, 9 insertions(+)