pefile: Parse the presumed PKCS#7 content of the certificate blob

Parse the content of the certificate blob, presuming it to be PKCS#7 format.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Reviewed-by: Kees Cook <keescook@chromium.org>

1 files changed, 20 insertions, 1 deletions

diff --git a/crypto/asymmetric_keys/verify_pefile.c b/crypto/asymmetric_keys/verify_pefile.c
index 2f5268cb843d..13f3b44b5046 100644
--- a/crypto/asymmetric_keys/verify_pefile.c
+++ b/crypto/asymmetric_keys/verify_pefile.c
@@ -216,7 +216,10 @@ static int pefile_strip_sig_wrapper(const void *pebuf,
 int verify_pefile_signature(const void *pebuf, unsigned pelen,
                             struct key *trusted_keyring, bool *_trusted)
 {
+        struct pkcs7_message *pkcs7;
         struct pefile_context ctx;
+        const void *data;
+        size_t datalen;
         int ret;
 
         kenter("");
@@ -230,5 +233,21 @@ int verify_pefile_signature(const void *pebuf, unsigned pelen,
         if (ret < 0)
                 return ret;
 
-        return -ENOANO; // Not yet complete
+        pkcs7 = pkcs7_parse_message(pebuf + ctx.sig_offset, ctx.sig_len);
+        if (IS_ERR(pkcs7))
+                return PTR_ERR(pkcs7);
+        ctx.pkcs7 = pkcs7;
+
+        ret = pkcs7_get_content_data(ctx.pkcs7, &data, &datalen, false);
+        if (ret < 0 || datalen == 0) {
+                pr_devel("PKCS#7 message does not contain data\n");
+                ret = -EBADMSG;
+                goto error;
+        }
+
+        ret = -ENOANO; // Not yet complete
+
+error:
+        pkcs7_free_message(ctx.pkcs7);
+        return ret;
 }