MODSIGN: Move the magic string to the end of a module and eliminate the search

[karo-tx-linux.git] / kernel / module_signing.c

diff --git a/kernel/module_signing.c b/kernel/module_signing.c
index 6b09f6983ac0d75ef35828ebacccb74db57a1817..d492a23df99c8a4fa99527b89c1223941229cb41 100644 (file)
--- a/kernel/module_signing.c
+++ b/kernel/module_signing.c
@@ -183,27 +183,33 @@ static struct key *request_asymmetric_key(const char *signer, size_t signer_len,
 /*
  * Verify the signature on a module.
  */
-int mod_verify_sig(const void *mod, unsigned long modlen,
-                  const void *sig, unsigned long siglen)
+int mod_verify_sig(const void *mod, unsigned long *_modlen)
 {
        struct public_key_signature *pks;
        struct module_signature ms;
        struct key *key;
-       size_t sig_len;
+       const void *sig;
+       size_t modlen = *_modlen, sig_len;
        int ret;
 
-       pr_devel("==>%s(,%lu,,%lu,)\n", __func__, modlen, siglen);
+       pr_devel("==>%s(,%lu)\n", __func__, modlen);
 
-       if (siglen <= sizeof(ms))
+       if (modlen <= sizeof(ms))
                return -EBADMSG;
 
-       memcpy(&ms, sig + (siglen - sizeof(ms)), sizeof(ms));
-       siglen -= sizeof(ms);
+       memcpy(&ms, mod + (modlen - sizeof(ms)), sizeof(ms));
+       modlen -= sizeof(ms);
 
        sig_len = be32_to_cpu(ms.sig_len);
-       if (sig_len >= siglen ||
-           siglen - sig_len != (size_t)ms.signer_len + ms.key_id_len)
+       if (sig_len >= modlen)
                return -EBADMSG;
+       modlen -= sig_len;
+       if ((size_t)ms.signer_len + ms.key_id_len >= modlen)
+               return -EBADMSG;
+       modlen -= (size_t)ms.signer_len + ms.key_id_len;
+
+       *_modlen = modlen;
+       sig = mod + modlen;
 
        /* For the moment, only support RSA and X.509 identifiers */
        if (ms.algo != PKEY_ALGO_RSA ||