This release fixes a number of security bugs and has minor new features and bug fixes. Security fixes, from the release notes (https://www.openssh.com/txt/release-9.3): This release contains fixes for a security problem and a memory safety problem. The memory safety problem is not believed to be exploitable, but we report most network-reachable memory faults as security bugs. * ssh-add(1): when adding smartcard keys to ssh-agent(1) with the per-hop destination constraints (ssh-add -h ...) added in OpenSSH 8.9, a logic error prevented the constraints from being communicated to the agent. This resulted in the keys being added without constraints. The common cases of non-smartcard keys and keys without destination constraints are unaffected. This problem was reported by Luci Stanescu. * ssh(1): Portable OpenSSH provides an implementation of the getrrsetbyname(3) function if the standard library does not provide it, for use by the VerifyHostKeyDNS feature. A specifically crafted DNS response could cause this function to perform an out-of-bounds read of adjacent stack data, but this condition does not appear to be exploitable beyond denial-of- service to the ssh(1) client. The getrrsetbyname(3) replacement is only included if the system's standard library lacks this function and portable OpenSSH was not compiled with the ldns library (--with-ldns). getrrsetbyname(3) is only invoked if using VerifyHostKeyDNS to fetch SSHFP records. This problem was found by the Coverity static analyzer. Sponsored by: The FreeBSD Foundation
469 lines
12 KiB
C
469 lines
12 KiB
C
/* $OpenBSD: ssh-ecdsa.c,v 1.26 2023/03/08 04:43:12 guenther Exp $ */
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/*
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* Copyright (c) 2000 Markus Friedl. All rights reserved.
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* Copyright (c) 2010 Damien Miller. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "includes.h"
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#if defined(WITH_OPENSSL) && defined(OPENSSL_HAS_ECC)
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#include <sys/types.h>
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#include <openssl/bn.h>
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#include <openssl/ec.h>
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#include <openssl/ecdsa.h>
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#include <openssl/evp.h>
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#include <string.h>
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#include "sshbuf.h"
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#include "ssherr.h"
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#include "digest.h"
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#define SSHKEY_INTERNAL
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#include "sshkey.h"
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#include "openbsd-compat/openssl-compat.h"
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static u_int
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ssh_ecdsa_size(const struct sshkey *key)
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{
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switch (key->ecdsa_nid) {
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case NID_X9_62_prime256v1:
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return 256;
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case NID_secp384r1:
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return 384;
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#ifdef OPENSSL_HAS_NISTP521
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case NID_secp521r1:
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return 521;
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#endif
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default:
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return 0;
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}
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}
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static void
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ssh_ecdsa_cleanup(struct sshkey *k)
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{
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EC_KEY_free(k->ecdsa);
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k->ecdsa = NULL;
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}
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static int
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ssh_ecdsa_equal(const struct sshkey *a, const struct sshkey *b)
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{
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const EC_GROUP *grp_a, *grp_b;
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const EC_POINT *pub_a, *pub_b;
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if (a->ecdsa == NULL || b->ecdsa == NULL)
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return 0;
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if ((grp_a = EC_KEY_get0_group(a->ecdsa)) == NULL ||
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(grp_b = EC_KEY_get0_group(b->ecdsa)) == NULL)
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return 0;
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if ((pub_a = EC_KEY_get0_public_key(a->ecdsa)) == NULL ||
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(pub_b = EC_KEY_get0_public_key(b->ecdsa)) == NULL)
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return 0;
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if (EC_GROUP_cmp(grp_a, grp_b, NULL) != 0)
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return 0;
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if (EC_POINT_cmp(grp_a, pub_a, pub_b, NULL) != 0)
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return 0;
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return 1;
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}
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static int
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ssh_ecdsa_serialize_public(const struct sshkey *key, struct sshbuf *b,
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enum sshkey_serialize_rep opts)
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{
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int r;
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if (key->ecdsa == NULL)
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return SSH_ERR_INVALID_ARGUMENT;
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if ((r = sshbuf_put_cstring(b,
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sshkey_curve_nid_to_name(key->ecdsa_nid))) != 0 ||
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(r = sshbuf_put_eckey(b, key->ecdsa)) != 0)
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return r;
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return 0;
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}
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static int
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ssh_ecdsa_serialize_private(const struct sshkey *key, struct sshbuf *b,
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enum sshkey_serialize_rep opts)
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{
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int r;
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if (!sshkey_is_cert(key)) {
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if ((r = ssh_ecdsa_serialize_public(key, b, opts)) != 0)
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return r;
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}
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if ((r = sshbuf_put_bignum2(b,
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EC_KEY_get0_private_key(key->ecdsa))) != 0)
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return r;
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return 0;
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}
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static int
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ssh_ecdsa_generate(struct sshkey *k, int bits)
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{
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EC_KEY *private;
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if ((k->ecdsa_nid = sshkey_ecdsa_bits_to_nid(bits)) == -1)
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return SSH_ERR_KEY_LENGTH;
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if ((private = EC_KEY_new_by_curve_name(k->ecdsa_nid)) == NULL)
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return SSH_ERR_ALLOC_FAIL;
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if (EC_KEY_generate_key(private) != 1) {
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EC_KEY_free(private);
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return SSH_ERR_LIBCRYPTO_ERROR;
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}
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EC_KEY_set_asn1_flag(private, OPENSSL_EC_NAMED_CURVE);
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k->ecdsa = private;
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return 0;
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}
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static int
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ssh_ecdsa_copy_public(const struct sshkey *from, struct sshkey *to)
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{
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to->ecdsa_nid = from->ecdsa_nid;
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if ((to->ecdsa = EC_KEY_new_by_curve_name(from->ecdsa_nid)) == NULL)
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return SSH_ERR_ALLOC_FAIL;
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if (EC_KEY_set_public_key(to->ecdsa,
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EC_KEY_get0_public_key(from->ecdsa)) != 1)
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return SSH_ERR_LIBCRYPTO_ERROR; /* caller will free k->ecdsa */
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return 0;
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}
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static int
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ssh_ecdsa_deserialize_public(const char *ktype, struct sshbuf *b,
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struct sshkey *key)
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{
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int r;
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char *curve = NULL;
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if ((key->ecdsa_nid = sshkey_ecdsa_nid_from_name(ktype)) == -1)
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return SSH_ERR_INVALID_ARGUMENT;
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if ((r = sshbuf_get_cstring(b, &curve, NULL)) != 0)
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goto out;
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if (key->ecdsa_nid != sshkey_curve_name_to_nid(curve)) {
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r = SSH_ERR_EC_CURVE_MISMATCH;
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goto out;
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}
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EC_KEY_free(key->ecdsa);
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key->ecdsa = NULL;
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if ((key->ecdsa = EC_KEY_new_by_curve_name(key->ecdsa_nid)) == NULL) {
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r = SSH_ERR_LIBCRYPTO_ERROR;
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goto out;
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}
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if ((r = sshbuf_get_eckey(b, key->ecdsa)) != 0)
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goto out;
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if (sshkey_ec_validate_public(EC_KEY_get0_group(key->ecdsa),
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EC_KEY_get0_public_key(key->ecdsa)) != 0) {
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r = SSH_ERR_KEY_INVALID_EC_VALUE;
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goto out;
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}
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/* success */
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r = 0;
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#ifdef DEBUG_PK
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sshkey_dump_ec_point(EC_KEY_get0_group(key->ecdsa),
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EC_KEY_get0_public_key(key->ecdsa));
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#endif
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out:
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free(curve);
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if (r != 0) {
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EC_KEY_free(key->ecdsa);
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key->ecdsa = NULL;
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}
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return r;
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}
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static int
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ssh_ecdsa_deserialize_private(const char *ktype, struct sshbuf *b,
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struct sshkey *key)
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{
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int r;
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BIGNUM *exponent = NULL;
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if (!sshkey_is_cert(key)) {
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if ((r = ssh_ecdsa_deserialize_public(ktype, b, key)) != 0)
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return r;
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}
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if ((r = sshbuf_get_bignum2(b, &exponent)) != 0)
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goto out;
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if (EC_KEY_set_private_key(key->ecdsa, exponent) != 1) {
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r = SSH_ERR_LIBCRYPTO_ERROR;
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goto out;
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}
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if ((r = sshkey_ec_validate_private(key->ecdsa)) != 0)
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goto out;
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/* success */
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r = 0;
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out:
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BN_clear_free(exponent);
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return r;
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}
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static int
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ssh_ecdsa_sign(struct sshkey *key,
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u_char **sigp, size_t *lenp,
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const u_char *data, size_t dlen,
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const char *alg, const char *sk_provider, const char *sk_pin, u_int compat)
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{
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ECDSA_SIG *esig = NULL;
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const BIGNUM *sig_r, *sig_s;
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int hash_alg;
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u_char digest[SSH_DIGEST_MAX_LENGTH];
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size_t len, hlen;
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struct sshbuf *b = NULL, *bb = NULL;
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int ret = SSH_ERR_INTERNAL_ERROR;
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if (lenp != NULL)
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*lenp = 0;
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if (sigp != NULL)
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*sigp = NULL;
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if (key == NULL || key->ecdsa == NULL ||
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sshkey_type_plain(key->type) != KEY_ECDSA)
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return SSH_ERR_INVALID_ARGUMENT;
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if ((hash_alg = sshkey_ec_nid_to_hash_alg(key->ecdsa_nid)) == -1 ||
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(hlen = ssh_digest_bytes(hash_alg)) == 0)
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return SSH_ERR_INTERNAL_ERROR;
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if ((ret = ssh_digest_memory(hash_alg, data, dlen,
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digest, sizeof(digest))) != 0)
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goto out;
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if ((esig = ECDSA_do_sign(digest, hlen, key->ecdsa)) == NULL) {
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ret = SSH_ERR_LIBCRYPTO_ERROR;
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goto out;
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}
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if ((bb = sshbuf_new()) == NULL || (b = sshbuf_new()) == NULL) {
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ret = SSH_ERR_ALLOC_FAIL;
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goto out;
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}
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ECDSA_SIG_get0(esig, &sig_r, &sig_s);
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if ((ret = sshbuf_put_bignum2(bb, sig_r)) != 0 ||
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(ret = sshbuf_put_bignum2(bb, sig_s)) != 0)
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goto out;
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if ((ret = sshbuf_put_cstring(b, sshkey_ssh_name_plain(key))) != 0 ||
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(ret = sshbuf_put_stringb(b, bb)) != 0)
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goto out;
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len = sshbuf_len(b);
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if (sigp != NULL) {
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if ((*sigp = malloc(len)) == NULL) {
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ret = SSH_ERR_ALLOC_FAIL;
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goto out;
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}
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memcpy(*sigp, sshbuf_ptr(b), len);
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}
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if (lenp != NULL)
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*lenp = len;
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ret = 0;
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out:
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explicit_bzero(digest, sizeof(digest));
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sshbuf_free(b);
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sshbuf_free(bb);
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ECDSA_SIG_free(esig);
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return ret;
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}
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static int
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ssh_ecdsa_verify(const struct sshkey *key,
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const u_char *sig, size_t siglen,
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const u_char *data, size_t dlen, const char *alg, u_int compat,
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struct sshkey_sig_details **detailsp)
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{
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ECDSA_SIG *esig = NULL;
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BIGNUM *sig_r = NULL, *sig_s = NULL;
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int hash_alg;
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u_char digest[SSH_DIGEST_MAX_LENGTH];
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size_t hlen;
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int ret = SSH_ERR_INTERNAL_ERROR;
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struct sshbuf *b = NULL, *sigbuf = NULL;
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char *ktype = NULL;
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if (key == NULL || key->ecdsa == NULL ||
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sshkey_type_plain(key->type) != KEY_ECDSA ||
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sig == NULL || siglen == 0)
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return SSH_ERR_INVALID_ARGUMENT;
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if ((hash_alg = sshkey_ec_nid_to_hash_alg(key->ecdsa_nid)) == -1 ||
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(hlen = ssh_digest_bytes(hash_alg)) == 0)
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return SSH_ERR_INTERNAL_ERROR;
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/* fetch signature */
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if ((b = sshbuf_from(sig, siglen)) == NULL)
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return SSH_ERR_ALLOC_FAIL;
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if (sshbuf_get_cstring(b, &ktype, NULL) != 0 ||
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sshbuf_froms(b, &sigbuf) != 0) {
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ret = SSH_ERR_INVALID_FORMAT;
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goto out;
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}
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if (strcmp(sshkey_ssh_name_plain(key), ktype) != 0) {
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ret = SSH_ERR_KEY_TYPE_MISMATCH;
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goto out;
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}
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if (sshbuf_len(b) != 0) {
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ret = SSH_ERR_UNEXPECTED_TRAILING_DATA;
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goto out;
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}
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/* parse signature */
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if (sshbuf_get_bignum2(sigbuf, &sig_r) != 0 ||
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sshbuf_get_bignum2(sigbuf, &sig_s) != 0) {
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ret = SSH_ERR_INVALID_FORMAT;
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goto out;
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}
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if ((esig = ECDSA_SIG_new()) == NULL) {
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ret = SSH_ERR_ALLOC_FAIL;
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goto out;
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}
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if (!ECDSA_SIG_set0(esig, sig_r, sig_s)) {
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ret = SSH_ERR_LIBCRYPTO_ERROR;
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goto out;
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}
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sig_r = sig_s = NULL; /* transferred */
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if (sshbuf_len(sigbuf) != 0) {
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ret = SSH_ERR_UNEXPECTED_TRAILING_DATA;
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goto out;
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}
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if ((ret = ssh_digest_memory(hash_alg, data, dlen,
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digest, sizeof(digest))) != 0)
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goto out;
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switch (ECDSA_do_verify(digest, hlen, esig, key->ecdsa)) {
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case 1:
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ret = 0;
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break;
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case 0:
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ret = SSH_ERR_SIGNATURE_INVALID;
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goto out;
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default:
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ret = SSH_ERR_LIBCRYPTO_ERROR;
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goto out;
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}
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out:
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explicit_bzero(digest, sizeof(digest));
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sshbuf_free(sigbuf);
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sshbuf_free(b);
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ECDSA_SIG_free(esig);
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BN_clear_free(sig_r);
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BN_clear_free(sig_s);
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free(ktype);
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return ret;
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}
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/* NB. not static; used by ECDSA-SK */
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const struct sshkey_impl_funcs sshkey_ecdsa_funcs = {
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/* .size = */ ssh_ecdsa_size,
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/* .alloc = */ NULL,
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/* .cleanup = */ ssh_ecdsa_cleanup,
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/* .equal = */ ssh_ecdsa_equal,
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/* .ssh_serialize_public = */ ssh_ecdsa_serialize_public,
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/* .ssh_deserialize_public = */ ssh_ecdsa_deserialize_public,
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/* .ssh_serialize_private = */ ssh_ecdsa_serialize_private,
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/* .ssh_deserialize_private = */ ssh_ecdsa_deserialize_private,
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/* .generate = */ ssh_ecdsa_generate,
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/* .copy_public = */ ssh_ecdsa_copy_public,
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/* .sign = */ ssh_ecdsa_sign,
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/* .verify = */ ssh_ecdsa_verify,
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};
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const struct sshkey_impl sshkey_ecdsa_nistp256_impl = {
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/* .name = */ "ecdsa-sha2-nistp256",
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/* .shortname = */ "ECDSA",
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/* .sigalg = */ NULL,
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/* .type = */ KEY_ECDSA,
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/* .nid = */ NID_X9_62_prime256v1,
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/* .cert = */ 0,
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/* .sigonly = */ 0,
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/* .keybits = */ 0,
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/* .funcs = */ &sshkey_ecdsa_funcs,
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};
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const struct sshkey_impl sshkey_ecdsa_nistp256_cert_impl = {
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/* .name = */ "ecdsa-sha2-nistp256-cert-v01@openssh.com",
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/* .shortname = */ "ECDSA-CERT",
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/* .sigalg = */ NULL,
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/* .type = */ KEY_ECDSA_CERT,
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/* .nid = */ NID_X9_62_prime256v1,
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/* .cert = */ 1,
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/* .sigonly = */ 0,
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/* .keybits = */ 0,
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/* .funcs = */ &sshkey_ecdsa_funcs,
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};
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const struct sshkey_impl sshkey_ecdsa_nistp384_impl = {
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/* .name = */ "ecdsa-sha2-nistp384",
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/* .shortname = */ "ECDSA",
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/* .sigalg = */ NULL,
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/* .type = */ KEY_ECDSA,
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/* .nid = */ NID_secp384r1,
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/* .cert = */ 0,
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/* .sigonly = */ 0,
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/* .keybits = */ 0,
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/* .funcs = */ &sshkey_ecdsa_funcs,
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};
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|
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const struct sshkey_impl sshkey_ecdsa_nistp384_cert_impl = {
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/* .name = */ "ecdsa-sha2-nistp384-cert-v01@openssh.com",
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/* .shortname = */ "ECDSA-CERT",
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/* .sigalg = */ NULL,
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/* .type = */ KEY_ECDSA_CERT,
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|
/* .nid = */ NID_secp384r1,
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/* .cert = */ 1,
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/* .sigonly = */ 0,
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/* .keybits = */ 0,
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/* .funcs = */ &sshkey_ecdsa_funcs,
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};
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#ifdef OPENSSL_HAS_NISTP521
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const struct sshkey_impl sshkey_ecdsa_nistp521_impl = {
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/* .name = */ "ecdsa-sha2-nistp521",
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/* .shortname = */ "ECDSA",
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/* .sigalg = */ NULL,
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/* .type = */ KEY_ECDSA,
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/* .nid = */ NID_secp521r1,
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/* .cert = */ 0,
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/* .sigonly = */ 0,
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/* .keybits = */ 0,
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/* .funcs = */ &sshkey_ecdsa_funcs,
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};
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const struct sshkey_impl sshkey_ecdsa_nistp521_cert_impl = {
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/* .name = */ "ecdsa-sha2-nistp521-cert-v01@openssh.com",
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/* .shortname = */ "ECDSA-CERT",
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/* .sigalg = */ NULL,
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/* .type = */ KEY_ECDSA_CERT,
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/* .nid = */ NID_secp521r1,
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/* .cert = */ 1,
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/* .sigonly = */ 0,
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/* .keybits = */ 0,
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/* .funcs = */ &sshkey_ecdsa_funcs,
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};
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#endif
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#endif /* WITH_OPENSSL && OPENSSL_HAS_ECC */
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