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| author | Maciej S. Szmigiero <mail@maciej.szmigiero.name> | 2018-05-19 14:23:54 +0200 |
|---|---|---|
| committer | James Morris <james.morris@microsoft.com> | 2018-06-25 12:17:08 -0700 |
| commit | b65c32ec5a942ab3ada93a048089a938918aba7f (patch) | |
| tree | d2925b709736bacd96191013a9309f4b875b0c0d | |
| parent | 7b4e88434c4e7982fb053c49657e1c8bbb8692d9 (diff) | |
| download | linux-next-b65c32ec5a942ab3ada93a048089a938918aba7f.tar.gz | |
X.509: unpack RSA signatureValue field from BIT STRING
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>
| -rw-r--r-- | crypto/asymmetric_keys/x509_cert_parser.c | 9 |
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 7d81e6bb461a..b6cabac4b62b 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; |