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-rw-r--r--ssh-dss.c457
1 files changed, 457 insertions, 0 deletions
diff --git a/ssh-dss.c b/ssh-dss.c
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+++ b/ssh-dss.c
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+/* $OpenBSD: ssh-dss.c,v 1.48 2022/10/28 00:44:44 djm Exp $ */
+/*
+ * Copyright (c) 2000 Markus Friedl. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "includes.h"
+
+#ifdef WITH_OPENSSL
+
+#include <sys/types.h>
+
+#include <openssl/bn.h>
+#include <openssl/dsa.h>
+#include <openssl/evp.h>
+
+#include <stdarg.h>
+#include <string.h>
+
+#include "sshbuf.h"
+#include "compat.h"
+#include "ssherr.h"
+#include "digest.h"
+#define SSHKEY_INTERNAL
+#include "sshkey.h"
+
+#include "openbsd-compat/openssl-compat.h"
+
+#define INTBLOB_LEN 20
+#define SIGBLOB_LEN (2*INTBLOB_LEN)
+
+static u_int
+ssh_dss_size(const struct sshkey *key)
+{
+ const BIGNUM *dsa_p;
+
+ if (key->dsa == NULL)
+ return 0;
+ DSA_get0_pqg(key->dsa, &dsa_p, NULL, NULL);
+ return BN_num_bits(dsa_p);
+}
+
+static int
+ssh_dss_alloc(struct sshkey *k)
+{
+ if ((k->dsa = DSA_new()) == NULL)
+ return SSH_ERR_ALLOC_FAIL;
+ return 0;
+}
+
+static void
+ssh_dss_cleanup(struct sshkey *k)
+{
+ DSA_free(k->dsa);
+ k->dsa = NULL;
+}
+
+static int
+ssh_dss_equal(const struct sshkey *a, const struct sshkey *b)
+{
+ const BIGNUM *dsa_p_a, *dsa_q_a, *dsa_g_a, *dsa_pub_key_a;
+ const BIGNUM *dsa_p_b, *dsa_q_b, *dsa_g_b, *dsa_pub_key_b;
+
+ if (a->dsa == NULL || b->dsa == NULL)
+ return 0;
+ DSA_get0_pqg(a->dsa, &dsa_p_a, &dsa_q_a, &dsa_g_a);
+ DSA_get0_pqg(b->dsa, &dsa_p_b, &dsa_q_b, &dsa_g_b);
+ DSA_get0_key(a->dsa, &dsa_pub_key_a, NULL);
+ DSA_get0_key(b->dsa, &dsa_pub_key_b, NULL);
+ if (dsa_p_a == NULL || dsa_p_b == NULL ||
+ dsa_q_a == NULL || dsa_q_b == NULL ||
+ dsa_g_a == NULL || dsa_g_b == NULL ||
+ dsa_pub_key_a == NULL || dsa_pub_key_b == NULL)
+ return 0;
+ if (BN_cmp(dsa_p_a, dsa_p_b) != 0)
+ return 0;
+ if (BN_cmp(dsa_q_a, dsa_q_b) != 0)
+ return 0;
+ if (BN_cmp(dsa_g_a, dsa_g_b) != 0)
+ return 0;
+ if (BN_cmp(dsa_pub_key_a, dsa_pub_key_b) != 0)
+ return 0;
+ return 1;
+}
+
+static int
+ssh_dss_serialize_public(const struct sshkey *key, struct sshbuf *b,
+ enum sshkey_serialize_rep opts)
+{
+ int r;
+ const BIGNUM *dsa_p, *dsa_q, *dsa_g, *dsa_pub_key;
+
+ if (key->dsa == NULL)
+ return SSH_ERR_INVALID_ARGUMENT;
+ DSA_get0_pqg(key->dsa, &dsa_p, &dsa_q, &dsa_g);
+ DSA_get0_key(key->dsa, &dsa_pub_key, NULL);
+ if (dsa_p == NULL || dsa_q == NULL ||
+ dsa_g == NULL || dsa_pub_key == NULL)
+ return SSH_ERR_INTERNAL_ERROR;
+ if ((r = sshbuf_put_bignum2(b, dsa_p)) != 0 ||
+ (r = sshbuf_put_bignum2(b, dsa_q)) != 0 ||
+ (r = sshbuf_put_bignum2(b, dsa_g)) != 0 ||
+ (r = sshbuf_put_bignum2(b, dsa_pub_key)) != 0)
+ return r;
+
+ return 0;
+}
+
+static int
+ssh_dss_serialize_private(const struct sshkey *key, struct sshbuf *b,
+ enum sshkey_serialize_rep opts)
+{
+ int r;
+ const BIGNUM *dsa_priv_key;
+
+ DSA_get0_key(key->dsa, NULL, &dsa_priv_key);
+ if (!sshkey_is_cert(key)) {
+ if ((r = ssh_dss_serialize_public(key, b, opts)) != 0)
+ return r;
+ }
+ if ((r = sshbuf_put_bignum2(b, dsa_priv_key)) != 0)
+ return r;
+
+ return 0;
+}
+
+static int
+ssh_dss_generate(struct sshkey *k, int bits)
+{
+ DSA *private;
+
+ if (bits != 1024)
+ return SSH_ERR_KEY_LENGTH;
+ if ((private = DSA_new()) == NULL)
+ return SSH_ERR_ALLOC_FAIL;
+ if (!DSA_generate_parameters_ex(private, bits, NULL, 0, NULL,
+ NULL, NULL) || !DSA_generate_key(private)) {
+ DSA_free(private);
+ return SSH_ERR_LIBCRYPTO_ERROR;
+ }
+ k->dsa = private;
+ return 0;
+}
+
+static int
+ssh_dss_copy_public(const struct sshkey *from, struct sshkey *to)
+{
+ const BIGNUM *dsa_p, *dsa_q, *dsa_g, *dsa_pub_key;
+ BIGNUM *dsa_p_dup = NULL, *dsa_q_dup = NULL, *dsa_g_dup = NULL;
+ BIGNUM *dsa_pub_key_dup = NULL;
+ int r = SSH_ERR_INTERNAL_ERROR;
+
+ DSA_get0_pqg(from->dsa, &dsa_p, &dsa_q, &dsa_g);
+ DSA_get0_key(from->dsa, &dsa_pub_key, NULL);
+ if ((dsa_p_dup = BN_dup(dsa_p)) == NULL ||
+ (dsa_q_dup = BN_dup(dsa_q)) == NULL ||
+ (dsa_g_dup = BN_dup(dsa_g)) == NULL ||
+ (dsa_pub_key_dup = BN_dup(dsa_pub_key)) == NULL) {
+ r = SSH_ERR_ALLOC_FAIL;
+ goto out;
+ }
+ if (!DSA_set0_pqg(to->dsa, dsa_p_dup, dsa_q_dup, dsa_g_dup)) {
+ r = SSH_ERR_LIBCRYPTO_ERROR;
+ goto out;
+ }
+ dsa_p_dup = dsa_q_dup = dsa_g_dup = NULL; /* transferred */
+ if (!DSA_set0_key(to->dsa, dsa_pub_key_dup, NULL)) {
+ r = SSH_ERR_LIBCRYPTO_ERROR;
+ goto out;
+ }
+ dsa_pub_key_dup = NULL; /* transferred */
+ /* success */
+ r = 0;
+ out:
+ BN_clear_free(dsa_p_dup);
+ BN_clear_free(dsa_q_dup);
+ BN_clear_free(dsa_g_dup);
+ BN_clear_free(dsa_pub_key_dup);
+ return r;
+}
+
+static int
+ssh_dss_deserialize_public(const char *ktype, struct sshbuf *b,
+ struct sshkey *key)
+{
+ int ret = SSH_ERR_INTERNAL_ERROR;
+ BIGNUM *dsa_p = NULL, *dsa_q = NULL, *dsa_g = NULL, *dsa_pub_key = NULL;
+
+ if (sshbuf_get_bignum2(b, &dsa_p) != 0 ||
+ sshbuf_get_bignum2(b, &dsa_q) != 0 ||
+ sshbuf_get_bignum2(b, &dsa_g) != 0 ||
+ sshbuf_get_bignum2(b, &dsa_pub_key) != 0) {
+ ret = SSH_ERR_INVALID_FORMAT;
+ goto out;
+ }
+ if (!DSA_set0_pqg(key->dsa, dsa_p, dsa_q, dsa_g)) {
+ ret = SSH_ERR_LIBCRYPTO_ERROR;
+ goto out;
+ }
+ dsa_p = dsa_q = dsa_g = NULL; /* transferred */
+ if (!DSA_set0_key(key->dsa, dsa_pub_key, NULL)) {
+ ret = SSH_ERR_LIBCRYPTO_ERROR;
+ goto out;
+ }
+ dsa_pub_key = NULL; /* transferred */
+#ifdef DEBUG_PK
+ DSA_print_fp(stderr, key->dsa, 8);
+#endif
+ /* success */
+ ret = 0;
+ out:
+ BN_clear_free(dsa_p);
+ BN_clear_free(dsa_q);
+ BN_clear_free(dsa_g);
+ BN_clear_free(dsa_pub_key);
+ return ret;
+}
+
+static int
+ssh_dss_deserialize_private(const char *ktype, struct sshbuf *b,
+ struct sshkey *key)
+{
+ int r;
+ BIGNUM *dsa_priv_key = NULL;
+
+ if (!sshkey_is_cert(key)) {
+ if ((r = ssh_dss_deserialize_public(ktype, b, key)) != 0)
+ return r;
+ }
+
+ if ((r = sshbuf_get_bignum2(b, &dsa_priv_key)) != 0)
+ return r;
+ if (!DSA_set0_key(key->dsa, NULL, dsa_priv_key)) {
+ BN_clear_free(dsa_priv_key);
+ return SSH_ERR_LIBCRYPTO_ERROR;
+ }
+ return 0;
+}
+
+static int
+ssh_dss_sign(struct sshkey *key,
+ u_char **sigp, size_t *lenp,
+ const u_char *data, size_t datalen,
+ const char *alg, const char *sk_provider, const char *sk_pin, u_int compat)
+{
+ DSA_SIG *sig = NULL;
+ const BIGNUM *sig_r, *sig_s;
+ u_char digest[SSH_DIGEST_MAX_LENGTH], sigblob[SIGBLOB_LEN];
+ size_t rlen, slen, len, dlen = ssh_digest_bytes(SSH_DIGEST_SHA1);
+ struct sshbuf *b = NULL;
+ int ret = SSH_ERR_INVALID_ARGUMENT;
+
+ if (lenp != NULL)
+ *lenp = 0;
+ if (sigp != NULL)
+ *sigp = NULL;
+
+ if (key == NULL || key->dsa == NULL ||
+ sshkey_type_plain(key->type) != KEY_DSA)
+ return SSH_ERR_INVALID_ARGUMENT;
+ if (dlen == 0)
+ return SSH_ERR_INTERNAL_ERROR;
+
+ if ((ret = ssh_digest_memory(SSH_DIGEST_SHA1, data, datalen,
+ digest, sizeof(digest))) != 0)
+ goto out;
+
+ if ((sig = DSA_do_sign(digest, dlen, key->dsa)) == NULL) {
+ ret = SSH_ERR_LIBCRYPTO_ERROR;
+ goto out;
+ }
+
+ DSA_SIG_get0(sig, &sig_r, &sig_s);
+ rlen = BN_num_bytes(sig_r);
+ slen = BN_num_bytes(sig_s);
+ if (rlen > INTBLOB_LEN || slen > INTBLOB_LEN) {
+ ret = SSH_ERR_INTERNAL_ERROR;
+ goto out;
+ }
+ explicit_bzero(sigblob, SIGBLOB_LEN);
+ BN_bn2bin(sig_r, sigblob + SIGBLOB_LEN - INTBLOB_LEN - rlen);
+ BN_bn2bin(sig_s, sigblob + SIGBLOB_LEN - slen);
+
+ if ((b = sshbuf_new()) == NULL) {
+ ret = SSH_ERR_ALLOC_FAIL;
+ goto out;
+ }
+ if ((ret = sshbuf_put_cstring(b, "ssh-dss")) != 0 ||
+ (ret = sshbuf_put_string(b, sigblob, SIGBLOB_LEN)) != 0)
+ goto out;
+
+ len = sshbuf_len(b);
+ if (sigp != NULL) {
+ if ((*sigp = malloc(len)) == NULL) {
+ ret = SSH_ERR_ALLOC_FAIL;
+ goto out;
+ }
+ memcpy(*sigp, sshbuf_ptr(b), len);
+ }
+ if (lenp != NULL)
+ *lenp = len;
+ ret = 0;
+ out:
+ explicit_bzero(digest, sizeof(digest));
+ DSA_SIG_free(sig);
+ sshbuf_free(b);
+ return ret;
+}
+
+static int
+ssh_dss_verify(const struct sshkey *key,
+ const u_char *sig, size_t siglen,
+ const u_char *data, size_t dlen, const char *alg, u_int compat,
+ struct sshkey_sig_details **detailsp)
+{
+ DSA_SIG *dsig = NULL;
+ BIGNUM *sig_r = NULL, *sig_s = NULL;
+ u_char digest[SSH_DIGEST_MAX_LENGTH], *sigblob = NULL;
+ size_t len, hlen = ssh_digest_bytes(SSH_DIGEST_SHA1);
+ int ret = SSH_ERR_INTERNAL_ERROR;
+ struct sshbuf *b = NULL;
+ char *ktype = NULL;
+
+ if (key == NULL || key->dsa == NULL ||
+ sshkey_type_plain(key->type) != KEY_DSA ||
+ sig == NULL || siglen == 0)
+ return SSH_ERR_INVALID_ARGUMENT;
+ if (hlen == 0)
+ return SSH_ERR_INTERNAL_ERROR;
+
+ /* fetch signature */
+ if ((b = sshbuf_from(sig, siglen)) == NULL)
+ return SSH_ERR_ALLOC_FAIL;
+ if (sshbuf_get_cstring(b, &ktype, NULL) != 0 ||
+ sshbuf_get_string(b, &sigblob, &len) != 0) {
+ ret = SSH_ERR_INVALID_FORMAT;
+ goto out;
+ }
+ if (strcmp("ssh-dss", ktype) != 0) {
+ ret = SSH_ERR_KEY_TYPE_MISMATCH;
+ goto out;
+ }
+ if (sshbuf_len(b) != 0) {
+ ret = SSH_ERR_UNEXPECTED_TRAILING_DATA;
+ goto out;
+ }
+
+ if (len != SIGBLOB_LEN) {
+ ret = SSH_ERR_INVALID_FORMAT;
+ goto out;
+ }
+
+ /* parse signature */
+ if ((dsig = DSA_SIG_new()) == NULL ||
+ (sig_r = BN_new()) == NULL ||
+ (sig_s = BN_new()) == NULL) {
+ ret = SSH_ERR_ALLOC_FAIL;
+ goto out;
+ }
+ if ((BN_bin2bn(sigblob, INTBLOB_LEN, sig_r) == NULL) ||
+ (BN_bin2bn(sigblob + INTBLOB_LEN, INTBLOB_LEN, sig_s) == NULL)) {
+ ret = SSH_ERR_LIBCRYPTO_ERROR;
+ goto out;
+ }
+ if (!DSA_SIG_set0(dsig, sig_r, sig_s)) {
+ ret = SSH_ERR_LIBCRYPTO_ERROR;
+ goto out;
+ }
+ sig_r = sig_s = NULL; /* transferred */
+
+ /* sha1 the data */
+ if ((ret = ssh_digest_memory(SSH_DIGEST_SHA1, data, dlen,
+ digest, sizeof(digest))) != 0)
+ goto out;
+
+ switch (DSA_do_verify(digest, hlen, dsig, key->dsa)) {
+ case 1:
+ ret = 0;
+ break;
+ case 0:
+ ret = SSH_ERR_SIGNATURE_INVALID;
+ goto out;
+ default:
+ ret = SSH_ERR_LIBCRYPTO_ERROR;
+ goto out;
+ }
+
+ out:
+ explicit_bzero(digest, sizeof(digest));
+ DSA_SIG_free(dsig);
+ BN_clear_free(sig_r);
+ BN_clear_free(sig_s);
+ sshbuf_free(b);
+ free(ktype);
+ if (sigblob != NULL)
+ freezero(sigblob, len);
+ return ret;
+}
+
+static const struct sshkey_impl_funcs sshkey_dss_funcs = {
+ /* .size = */ ssh_dss_size,
+ /* .alloc = */ ssh_dss_alloc,
+ /* .cleanup = */ ssh_dss_cleanup,
+ /* .equal = */ ssh_dss_equal,
+ /* .ssh_serialize_public = */ ssh_dss_serialize_public,
+ /* .ssh_deserialize_public = */ ssh_dss_deserialize_public,
+ /* .ssh_serialize_private = */ ssh_dss_serialize_private,
+ /* .ssh_deserialize_private = */ ssh_dss_deserialize_private,
+ /* .generate = */ ssh_dss_generate,
+ /* .copy_public = */ ssh_dss_copy_public,
+ /* .sign = */ ssh_dss_sign,
+ /* .verify = */ ssh_dss_verify,
+};
+
+const struct sshkey_impl sshkey_dss_impl = {
+ /* .name = */ "ssh-dss",
+ /* .shortname = */ "DSA",
+ /* .sigalg = */ NULL,
+ /* .type = */ KEY_DSA,
+ /* .nid = */ 0,
+ /* .cert = */ 0,
+ /* .sigonly = */ 0,
+ /* .keybits = */ 0,
+ /* .funcs = */ &sshkey_dss_funcs,
+};
+
+const struct sshkey_impl sshkey_dsa_cert_impl = {
+ /* .name = */ "ssh-dss-cert-v01@openssh.com",
+ /* .shortname = */ "DSA-CERT",
+ /* .sigalg = */ NULL,
+ /* .type = */ KEY_DSA_CERT,
+ /* .nid = */ 0,
+ /* .cert = */ 1,
+ /* .sigonly = */ 0,
+ /* .keybits = */ 0,
+ /* .funcs = */ &sshkey_dss_funcs,
+};
+#endif /* WITH_OPENSSL */