upstream commit

Refuse RSA keys <1024 bits in length. Improve reporting
for keys that do not meet this requirement. ok markus@

Upstream-ID: b385e2a7b13b1484792ee681daaf79e1e203df6c

diff --git a/ssh-keygen.c b/ssh-keygen.c
index 51c24bc55902ba6a88a0dfa834ad4f1d1fed4850..7886582d790621c6673286adc3291d813e18f6e7 100644 (file)
--- a/ssh-keygen.c
+++ b/ssh-keygen.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssh-keygen.c,v 1.302 2017/04/30 23:18:44 djm Exp $ */
+/* $OpenBSD: ssh-keygen.c,v 1.303 2017/05/07 23:15:59 djm Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1994 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -226,13 +226,21 @@ type_bits_valid(int type, const char *name, u_int32_t *bitsp)
            OPENSSL_DSA_MAX_MODULUS_BITS : OPENSSL_RSA_MAX_MODULUS_BITS;
        if (*bitsp > maxbits)
                fatal("key bits exceeds maximum %d", maxbits);
-       if (type == KEY_DSA && *bitsp != 1024)
-               fatal("DSA keys must be 1024 bits");
-       else if (type != KEY_ECDSA && type != KEY_ED25519 && *bitsp < 1024)
-               fatal("Key must at least be 1024 bits");
-       else if (type == KEY_ECDSA && sshkey_ecdsa_bits_to_nid(*bitsp) == -1)
-               fatal("Invalid ECDSA key length - valid lengths are "
-                   "256, 384 or 521 bits");
+       switch (type) {
+       case KEY_DSA:
+               if (*bitsp != 1024)
+                       fatal("Invalid DSA key length: must be 1024 bits");
+               break;
+       case KEY_RSA:
+               if (*bitsp < SSH_RSA_MINIMUM_MODULUS_SIZE)
+                       fatal("Invalid RSA key length: minimum is %d bits",
+                           SSH_RSA_MINIMUM_MODULUS_SIZE);
+               break;
+       case KEY_ECDSA:
+               if (sshkey_ecdsa_bits_to_nid(*bitsp) == -1)
+                       fatal("Invalid ECDSA key length: valid lengths are "
+                           "256, 384 or 521 bits");
+       }
 #endif
 }
 

diff --git a/ssh-rsa.c b/ssh-rsa.c
index cde05df10143c9561d0b44c24246037993c59a5f..e8acc01fa8a8a82eafbb7f1279f66851c55aad2d 100644 (file)
--- a/ssh-rsa.c
+++ b/ssh-rsa.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssh-rsa.c,v 1.60 2016/09/12 23:39:34 djm Exp $ */
+/* $OpenBSD: ssh-rsa.c,v 1.61 2017/05/07 23:15:59 djm Exp $ */
 /*
  * Copyright (c) 2000, 2003 Markus Friedl <markus@openbsd.org>
  *
@@ -99,9 +99,10 @@ ssh_rsa_sign(const struct sshkey *key, u_char **sigp, size_t *lenp,
        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)
+           sshkey_type_plain(key->type) != KEY_RSA)
                return SSH_ERR_INVALID_ARGUMENT;
+       if (BN_num_bits(key->rsa->n) < SSH_RSA_MINIMUM_MODULUS_SIZE)
+               return SSH_ERR_KEY_LENGTH;
        slen = RSA_size(key->rsa);
        if (slen <= 0 || slen > SSHBUF_MAX_BIGNUM)
                return SSH_ERR_INVALID_ARGUMENT;
@@ -172,9 +173,10 @@ ssh_rsa_verify(const struct sshkey *key,
 
        if (key == NULL || key->rsa == NULL ||
            sshkey_type_plain(key->type) != KEY_RSA ||
-           BN_num_bits(key->rsa->n) < SSH_RSA_MINIMUM_MODULUS_SIZE ||
            sig == NULL || siglen == 0)
                return SSH_ERR_INVALID_ARGUMENT;
+       if (BN_num_bits(key->rsa->n) < SSH_RSA_MINIMUM_MODULUS_SIZE)
+               return SSH_ERR_KEY_LENGTH;
 
        if ((b = sshbuf_from(sig, siglen)) == NULL)
                return SSH_ERR_ALLOC_FAIL;

diff --git a/ssh.h b/ssh.h
index 08d05ce293c224f4c36353bd5b053ee16b36c81f..12d80092250caad23011b9e37cd4e3f4bd955f5f 100644 (file)
--- a/ssh.h
+++ b/ssh.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssh.h,v 1.86 2017/05/03 21:08:09 naddy Exp $ */
+/* $OpenBSD: ssh.h,v 1.87 2017/05/07 23:15:59 djm Exp $ */
 
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
@@ -98,8 +98,5 @@
 #define SSH_PRIVSEP_USER               "sshd"
 #endif
 
-/* Minimum modulus size (n) for RSA keys. */
-#define SSH_RSA_MINIMUM_MODULUS_SIZE   768
-
 /* Listen backlog for sshd, ssh-agent and forwarding sockets */
 #define SSH_LISTEN_BACKLOG             128

diff --git a/ssherr.c b/ssherr.c
index 68020706381ca1d15dc3810451e191e346f5cc2e..4bd5f59cc9ca4d443949d8a42b6076357b950cb0 100644 (file)
--- a/ssherr.c
+++ b/ssherr.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: ssherr.c,v 1.5 2015/09/13 14:39:16 tim Exp $  */
+/*     $OpenBSD: ssherr.c,v 1.6 2017/05/07 23:15:59 djm Exp $  */
 /*
  * Copyright (c) 2011 Damien Miller
  *
@@ -135,6 +135,8 @@ ssh_err(int n)
                return "Connection corrupted";
        case SSH_ERR_PROTOCOL_ERROR:
                return "Protocol error";
+       case SSH_ERR_KEY_LENGTH:
+               return "Invalid key length";
        default:
                return "unknown error";
        }

diff --git a/ssherr.h b/ssherr.h
index 6f771b4b78be376b5ace7a1fcfc0b1ca595ac9f0..a30781620fa9d5ea507be4a9356cf9652ce39cf7 100644 (file)
--- a/ssherr.h
+++ b/ssherr.h
@@ -1,4 +1,4 @@
-/*     $OpenBSD: ssherr.h,v 1.3 2015/01/30 01:13:33 djm Exp $  */
+/*     $OpenBSD: ssherr.h,v 1.4 2017/05/07 23:15:59 djm Exp $  */
 /*
  * Copyright (c) 2011 Damien Miller
  *
@@ -77,6 +77,7 @@
 #define SSH_ERR_CONN_TIMEOUT                   -53
 #define SSH_ERR_CONN_CORRUPT                   -54
 #define SSH_ERR_PROTOCOL_ERROR                 -55
+#define SSH_ERR_KEY_LENGTH                     -56
 
 /* Translate a numeric error code to a human-readable error string */
 const char *ssh_err(int n);

diff --git a/sshkey.c b/sshkey.c
index 0f6468197b0d80349f62010aa8bcefcc16736ed2..6518c6f0ba0d86e564fe5819ac8f43ac377488eb 100644 (file)
--- a/sshkey.c
+++ b/sshkey.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: sshkey.c,v 1.48 2017/04/30 23:18:44 djm Exp $ */
+/* $OpenBSD: sshkey.c,v 1.49 2017/05/07 23:15:59 djm Exp $ */
 /*
  * Copyright (c) 2000, 2001 Markus Friedl.  All rights reserved.
  * Copyright (c) 2008 Alexander von Gernler.  All rights reserved.
@@ -1392,10 +1392,11 @@ rsa_generate_private_key(u_int bits, RSA **rsap)
        BIGNUM *f4 = NULL;
        int ret = SSH_ERR_INTERNAL_ERROR;
 
-       if (rsap == NULL ||
-           bits < SSH_RSA_MINIMUM_MODULUS_SIZE ||
-           bits > SSHBUF_MAX_BIGNUM * 8)
+       if (rsap == NULL)
                return SSH_ERR_INVALID_ARGUMENT;
+       if (bits < SSH_RSA_MINIMUM_MODULUS_SIZE ||
+           bits > SSHBUF_MAX_BIGNUM * 8)
+               return SSH_ERR_KEY_LENGTH;
        *rsap = NULL;
        if ((private = RSA_new()) == NULL || (f4 = BN_new()) == NULL) {
                ret = SSH_ERR_ALLOC_FAIL;
@@ -1423,8 +1424,10 @@ dsa_generate_private_key(u_int bits, DSA **dsap)
        DSA *private;
        int ret = SSH_ERR_INTERNAL_ERROR;
 
-       if (dsap == NULL || bits != 1024)
+       if (dsap == NULL)
                return SSH_ERR_INVALID_ARGUMENT;
+       if (bits != 1024)
+               return SSH_ERR_KEY_LENGTH;
        if ((private = DSA_new()) == NULL) {
                ret = SSH_ERR_ALLOC_FAIL;
                goto out;
@@ -1876,6 +1879,10 @@ sshkey_from_blob_internal(struct sshbuf *b, struct sshkey **keyp,
                        ret = SSH_ERR_INVALID_FORMAT;
                        goto out;
                }
+               if (BN_num_bits(key->rsa->n) < SSH_RSA_MINIMUM_MODULUS_SIZE) {
+                       ret = SSH_ERR_KEY_LENGTH;
+                       goto out;
+               }
 #ifdef DEBUG_PK
                RSA_print_fp(stderr, key->rsa, 8);
 #endif
@@ -2643,6 +2650,10 @@ sshkey_private_deserialize(struct sshbuf *buf, struct sshkey **kp)
                    (r = sshbuf_get_bignum2(buf, k->rsa->q)) != 0 ||
                    (r = rsa_generate_additional_parameters(k->rsa)) != 0)
                        goto out;
+               if (BN_num_bits(k->rsa->n) < SSH_RSA_MINIMUM_MODULUS_SIZE) {
+                       r = SSH_ERR_KEY_LENGTH;
+                       goto out;
+               }
                break;
        case KEY_RSA_CERT:
                if ((r = sshkey_froms(buf, &k)) != 0 ||
@@ -2653,6 +2664,10 @@ sshkey_private_deserialize(struct sshbuf *buf, struct sshkey **kp)
                    (r = sshbuf_get_bignum2(buf, k->rsa->q)) != 0 ||
                    (r = rsa_generate_additional_parameters(k->rsa)) != 0)
                        goto out;
+               if (BN_num_bits(k->rsa->n) < SSH_RSA_MINIMUM_MODULUS_SIZE) {
+                       r = SSH_ERR_KEY_LENGTH;
+                       goto out;
+               }
                break;
 #endif /* WITH_OPENSSL */
        case KEY_ED25519:
@@ -3427,6 +3442,10 @@ sshkey_parse_private_pem_fileblob(struct sshbuf *blob, int type,
                        r = SSH_ERR_LIBCRYPTO_ERROR;
                        goto out;
                }
+               if (BN_num_bits(prv->rsa->n) < SSH_RSA_MINIMUM_MODULUS_SIZE) {
+                       r = SSH_ERR_KEY_LENGTH;
+                       goto out;
+               }
        } else if (pk->type == EVP_PKEY_DSA &&
            (type == KEY_UNSPEC || type == KEY_DSA)) {
                if ((prv = sshkey_new(KEY_UNSPEC)) == NULL) {

diff --git a/sshkey.h b/sshkey.h
index fc19566054c69a7188c4a5b8d9727c3f1ed0afd5..b0b5b2749bf17af36a43ba3b1ce304d8b8025a7e 100644 (file)
--- a/sshkey.h
+++ b/sshkey.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: sshkey.h,v 1.17 2017/05/03 21:08:09 naddy Exp $ */
+/* $OpenBSD: sshkey.h,v 1.18 2017/05/07 23:15:59 djm Exp $ */
 
 /*
  * Copyright (c) 2000, 2001 Markus Friedl.  All rights reserved.
@@ -46,7 +46,7 @@
 # define EC_POINT      void
 #endif /* WITH_OPENSSL */
 
-#define SSH_RSA_MINIMUM_MODULUS_SIZE   768
+#define SSH_RSA_MINIMUM_MODULUS_SIZE   1024
 #define SSH_KEY_MAX_SIGN_DATA_SIZE     (1 << 20)
 
 struct sshbuf;