Check packet types of signatures and public keys

pgpVerifySignature() should check that the provided signature is in fact
a signature, and that provided key is in fact a public key.  Otherwise,
a type confusion bug could result if something that is not a signature
or public key is passed.  RPM itself never calls pgpVerifySignature()
without having checked the types so all calls in RPM are safe.

1 files changed, 11 insertions, 3 deletions

diff --git a/rpmio/rpmpgp_internal.c b/rpmio/rpmpgp_internal.c
index e2615a22c..3ae6ebd9d 100644
--- a/rpmio/rpmpgp_internal.c
+++ b/rpmio/rpmpgp_internal.c
@@ -568,6 +568,11 @@ static int pgpCurveByOid(const uint8_t *p, int l)
     return 0;
 }
 
+static int isKey(pgpDigParams keyp)
+{
+    return keyp->tag == PGPTAG_PUBLIC_KEY || keyp->tag == PGPTAG_PUBLIC_SUBKEY;
+}
+
 static int pgpPrtPubkeyParams(uint8_t pubkey_algo,
 		const uint8_t *p, const uint8_t *h, size_t hlen,
 		pgpDigParams keyp)
@@ -586,9 +591,7 @@ static int pgpPrtPubkeyParams(uint8_t pubkey_algo,
     rc = processMpis(keyalg->mpis, keyalg, p, pend);
 
     /* We can't handle more than one key at a time */
-    if (rc == 0 && keyp->alg == NULL && (keyp->tag == PGPTAG_PUBLIC_KEY ||
-	keyp->tag == PGPTAG_PUBLIC_SUBKEY))
-
+    if (rc == 0 && keyp->alg == NULL && isKey(keyp))
 	keyp->alg = keyalg;
     else
 	pgpDigAlgFree(keyalg);
@@ -1124,6 +1127,9 @@ rpmRC pgpVerifySignature(pgpDigParams key, pgpDigParams sig, DIGEST_CTX hashctx)
     if (sig == NULL || ctx == NULL)
 	goto exit;
 
+    if (sig->tag != PGPTAG_SIGNATURE)
+	goto exit;
+
     if (sig->hash != NULL)
 	rpmDigestUpdate(ctx, sig->hash, sig->hashlen);
 
@@ -1150,6 +1156,8 @@ rpmRC pgpVerifySignature(pgpDigParams key, pgpDigParams sig, DIGEST_CTX hashctx)
      * done all we can, return NOKEY to indicate "looks okay but dunno."
      */
     if (key && key->alg) {
+	if (!isKey(key))
+	    goto exit;
 	pgpDigAlg sa = sig->alg;
 	pgpDigAlg ka = key->alg;
 	if (sa && sa->verify && sig->pubkey_algo == key->pubkey_algo) {