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authorMaciej S. Szmigiero <mail@maciej.szmigiero.name>2018-05-19 15:23:54 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-07-03 12:23:11 +0300
commit41b1d57a672f45f1d3a158cf28c24f1885201c9e (patch)
treedff0d9109f6a703647c67d10eb3dbbba52cc2211 /crypto
parent8fd86587ea975c2dc324c7c5bf804619bcea22b6 (diff)
downloadlinux-41b1d57a672f45f1d3a158cf28c24f1885201c9e.tar.xz
X.509: unpack RSA signatureValue field from BIT STRING
commit b65c32ec5a942ab3ada93a048089a938918aba7f upstream. 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 Signed-off-by: James Morris <james.morris@microsoft.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'crypto')
-rw-r--r--crypto/asymmetric_keys/x509_cert_parser.c9
1 files changed, 9 insertions, 0 deletions
diff --git a/crypto/asymmetric_keys/x509_cert_parser.c b/crypto/asymmetric_keys/x509_cert_parser.c
index ce2df8c9c583..7e6a43ffdcbe 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") == 0) {
+ /* 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;