commit 6262a0522ddc2c0f2e9358dcb68d59b46e9c533e
author markus@openbsd.org <markus@openbsd.org> Mon Dec 07 20:04:09 2015 +0000
committer Damien Miller <djm@mindrot.org> Fri Dec 11 13:23:13 2015 +1100
tree 85aa7d8b0cee6dfbc2115fc082822c490086008d
parent d86a3ba7af160c13496102aed861ae48a4297072

upstream commit

stricter encoding type checks for ssh-rsa; ok djm@

Upstream-ID: 8cca7c787599a5e8391e184d0b4f36fdc3665650

ssh-rsa.c

diff --git a/ssh-rsa.c b/ssh-rsa.c
index 81dab05..6b85895 100644
--- a/ssh-rsa.c
+++ b/ssh-rsa.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssh-rsa.c,v 1.55 2015/12/04 16:41:28 markus Exp $ */
+/* $OpenBSD: ssh-rsa.c,v 1.56 2015/12/07 20:04:09 markus Exp $ */
 /*
  * Copyright (c) 2000, 2003 Markus Friedl <markus@openbsd.org>
  *
@@ -53,16 +53,12 @@
 static int
 rsa_hash_alg_from_ident(const char *ident)
 {
-	if (ident == NULL || strlen(ident) == 0)
-		return SSH_DIGEST_SHA1;
 	if (strcmp(ident, "ssh-rsa") == 0)
 		return SSH_DIGEST_SHA1;
 	if (strcmp(ident, "rsa-sha2-256") == 0)
 		return SSH_DIGEST_SHA256;
 	if (strcmp(ident, "rsa-sha2-512") == 0)
 		return SSH_DIGEST_SHA512;
-	if (strncmp(ident, "ssh-rsa-cert", strlen("ssh-rsa-cert")) == 0)
-		return SSH_DIGEST_SHA1;
 	return -1;
 }
 
@@ -97,7 +93,11 @@
 	if (sigp != NULL)
 		*sigp = NULL;
 
-	hash_alg = rsa_hash_alg_from_ident(alg_ident);
+	if (alg_ident == NULL || strlen(alg_ident) == 0 ||
+	    strncmp(alg_ident, "ssh-rsa-cert", strlen("ssh-rsa-cert")) == 0)
+		hash_alg = SSH_DIGEST_SHA1;
+	else
+		hash_alg = rsa_hash_alg_from_ident(alg_ident);
 	if (key == NULL || key->rsa == NULL || hash_alg == -1 ||
 	    sshkey_type_plain(key->type) != KEY_RSA ||
 	    BN_num_bits(key->rsa->n) < SSH_RSA_MINIMUM_MODULUS_SIZE)