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PKCS#7: Find the right key in the PKCS#7 key list and verify the signature 

Find the appropriate key in the PKCS#7 key list and verify the signature with
it.  There may be several keys in there forming a chain.  Any link in that
chain or the root of that chain may be in our keyrings.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
This commit is contained in:
David Howells 2014-07-01 16:40:19 +01:00
parent 9f0d33146e
commit a4730357ee
2 changed files with 69 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

64
crypto/asymmetric_keys/pkcs7_verify.c
View File

@ -120,6 +120,55 @@ error_no_desc:
}
/*
* Find the key (X.509 certificate) to use to verify a PKCS#7 message. PKCS#7
* uses the issuer's name and the issuing certificate serial number for
* matching purposes. These must match the certificate issuer's name (not
* subject's name) and the certificate serial number [RFC 2315 6.7].
*/
static int pkcs7_find_key(struct pkcs7_message *pkcs7,
struct pkcs7_signed_info *sinfo)
{
struct x509_certificate *x509;
unsigned certix = 1;
kenter("%u,%u,%u",
sinfo->index, sinfo->raw_serial_size, sinfo->raw_issuer_size);
for (x509 = pkcs7->certs; x509; x509 = x509->next, certix++) {
/* I'm _assuming_ that the generator of the PKCS#7 message will
* encode the fields from the X.509 cert in the same way in the
* PKCS#7 message - but I can't be 100% sure of that. It's
* possible this will need element-by-element comparison.
*/
if (x509->raw_serial_size != sinfo->raw_serial_size ||
memcmp(x509->raw_serial, sinfo->raw_serial,
sinfo->raw_serial_size) != 0)
continue;
pr_devel("Sig %u: Found cert serial match X.509[%u]\n",
sinfo->index, certix);
if (x509->raw_issuer_size != sinfo->raw_issuer_size ||
memcmp(x509->raw_issuer, sinfo->raw_issuer,
sinfo->raw_issuer_size) != 0) {
pr_warn("Sig %u: X.509 subject and PKCS#7 issuer don't match\n",
sinfo->index);
continue;
}
if (x509->pub->pkey_algo != sinfo->sig.pkey_algo) {
pr_warn("Sig %u: X.509 algo and PKCS#7 sig algo don't match\n",
sinfo->index);
continue;
}
sinfo->signer = x509;
return 0;
}
pr_warn("Sig %u: Issuing X.509 cert not found (#%*ph)\n",
sinfo->index, sinfo->raw_serial_size, sinfo->raw_serial);
return -ENOKEY;
}
/*
* Verify one signed information block from a PKCS#7 message.
*/
@ -137,6 +186,21 @@ static int pkcs7_verify_one(struct pkcs7_message *pkcs7,
if (ret < 0)
return ret;
/* Find the key for the signature */
ret = pkcs7_find_key(pkcs7, sinfo);
if (ret < 0)
return ret;
pr_devel("Using X.509[%u] for sig %u\n",
sinfo->signer->index, sinfo->index);
/* Verify the PKCS#7 binary against the key */
ret = public_key_verify_signature(sinfo->signer->pub, &sinfo->sig);
if (ret < 0)
return ret;
pr_devel("Verified signature %u\n", sinfo->index);
return 0;
}

5
include/crypto/pkcs7.h
View File

@ -21,3 +21,8 @@ extern void pkcs7_free_message(struct pkcs7_message *pkcs7);
extern int pkcs7_get_content_data(const struct pkcs7_message *pkcs7,
const void **_data, size_t *_datalen,
bool want_wrapper);
/*
* pkcs7_verify.c
*/
extern int pkcs7_verify(struct pkcs7_message *pkcs7);