1/*	$OpenBSD: sshbuf-getput-crypto.c,v 1.11 2024/02/01 02:37:33 djm Exp $	*/
2/*
3 * Copyright (c) 2011 Damien Miller
4 *
5 * Permission to use, copy, modify, and distribute this software for any
6 * purpose with or without fee is hereby granted, provided that the above
7 * copyright notice and this permission notice appear in all copies.
8 *
9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16 */
17
18#define SSHBUF_INTERNAL
19#include "includes.h"
20
21#include <sys/types.h>
22#include <stdlib.h>
23#include <stdio.h>
24#include <string.h>
25
26#ifdef WITH_OPENSSL
27#include <openssl/bn.h>
28#ifdef OPENSSL_HAS_ECC
29# include <openssl/ec.h>
30#endif /* OPENSSL_HAS_ECC */
31
32#include "ssherr.h"
33#include "sshbuf.h"
34
35int
36sshbuf_get_bignum2(struct sshbuf *buf, BIGNUM **valp)
37{
38	BIGNUM *v;
39	const u_char *d;
40	size_t len;
41	int r;
42
43	if (valp != NULL)
44		*valp = NULL;
45	if ((r = sshbuf_get_bignum2_bytes_direct(buf, &d, &len)) != 0)
46		return r;
47	if (valp != NULL) {
48		if ((v = BN_new()) == NULL ||
49		    BN_bin2bn(d, len, v) == NULL) {
50			BN_clear_free(v);
51			return SSH_ERR_ALLOC_FAIL;
52		}
53		*valp = v;
54	}
55	return 0;
56}
57
58#ifdef OPENSSL_HAS_ECC
59static int
60get_ec(const u_char *d, size_t len, EC_POINT *v, const EC_GROUP *g)
61{
62	/* Refuse overlong bignums */
63	if (len == 0 || len > SSHBUF_MAX_ECPOINT)
64		return SSH_ERR_ECPOINT_TOO_LARGE;
65	/* Only handle uncompressed points */
66	if (*d != POINT_CONVERSION_UNCOMPRESSED)
67		return SSH_ERR_INVALID_FORMAT;
68	if (v != NULL && EC_POINT_oct2point(g, v, d, len, NULL) != 1)
69		return SSH_ERR_INVALID_FORMAT; /* XXX assumption */
70	return 0;
71}
72
73int
74sshbuf_get_ec(struct sshbuf *buf, EC_POINT *v, const EC_GROUP *g)
75{
76	const u_char *d;
77	size_t len;
78	int r;
79
80	if ((r = sshbuf_peek_string_direct(buf, &d, &len)) < 0)
81		return r;
82	if ((r = get_ec(d, len, v, g)) != 0)
83		return r;
84	/* Skip string */
85	if (sshbuf_get_string_direct(buf, NULL, NULL) != 0) {
86		/* Shouldn't happen */
87		SSHBUF_DBG(("SSH_ERR_INTERNAL_ERROR"));
88		SSHBUF_ABORT();
89		return SSH_ERR_INTERNAL_ERROR;
90	}
91	return 0;
92}
93
94int
95sshbuf_get_eckey(struct sshbuf *buf, EC_KEY *v)
96{
97	EC_POINT *pt = EC_POINT_new(EC_KEY_get0_group(v));
98	int r;
99	const u_char *d;
100	size_t len;
101
102	if (pt == NULL) {
103		SSHBUF_DBG(("SSH_ERR_ALLOC_FAIL"));
104		return SSH_ERR_ALLOC_FAIL;
105	}
106	if ((r = sshbuf_peek_string_direct(buf, &d, &len)) < 0) {
107		EC_POINT_free(pt);
108		return r;
109	}
110	if ((r = get_ec(d, len, pt, EC_KEY_get0_group(v))) != 0) {
111		EC_POINT_free(pt);
112		return r;
113	}
114	if (EC_KEY_set_public_key(v, pt) != 1) {
115		EC_POINT_free(pt);
116		return SSH_ERR_ALLOC_FAIL; /* XXX assumption */
117	}
118	EC_POINT_free(pt);
119	/* Skip string */
120	if (sshbuf_get_string_direct(buf, NULL, NULL) != 0) {
121		/* Shouldn't happen */
122		SSHBUF_DBG(("SSH_ERR_INTERNAL_ERROR"));
123		SSHBUF_ABORT();
124		return SSH_ERR_INTERNAL_ERROR;
125	}
126	return 0;
127}
128#endif /* OPENSSL_HAS_ECC */
129
130int
131sshbuf_put_bignum2(struct sshbuf *buf, const BIGNUM *v)
132{
133	u_char d[SSHBUF_MAX_BIGNUM + 1];
134	int len = BN_num_bytes(v), prepend = 0, r;
135
136	if (len < 0 || len > SSHBUF_MAX_BIGNUM)
137		return SSH_ERR_INVALID_ARGUMENT;
138	*d = '\0';
139	if (BN_bn2bin(v, d + 1) != len)
140		return SSH_ERR_INTERNAL_ERROR; /* Shouldn't happen */
141	/* If MSB is set, prepend a \0 */
142	if (len > 0 && (d[1] & 0x80) != 0)
143		prepend = 1;
144	if ((r = sshbuf_put_string(buf, d + 1 - prepend, len + prepend)) < 0) {
145		explicit_bzero(d, sizeof(d));
146		return r;
147	}
148	explicit_bzero(d, sizeof(d));
149	return 0;
150}
151
152#ifdef OPENSSL_HAS_ECC
153int
154sshbuf_put_ec(struct sshbuf *buf, const EC_POINT *v, const EC_GROUP *g)
155{
156	u_char d[SSHBUF_MAX_ECPOINT];
157	size_t len;
158	int ret;
159
160	if ((len = EC_POINT_point2oct(g, v, POINT_CONVERSION_UNCOMPRESSED,
161	    NULL, 0, NULL)) > SSHBUF_MAX_ECPOINT) {
162		return SSH_ERR_INVALID_ARGUMENT;
163	}
164	if (EC_POINT_point2oct(g, v, POINT_CONVERSION_UNCOMPRESSED,
165	    d, len, NULL) != len) {
166		return SSH_ERR_INTERNAL_ERROR; /* Shouldn't happen */
167	}
168	ret = sshbuf_put_string(buf, d, len);
169	explicit_bzero(d, len);
170	return ret;
171}
172
173int
174sshbuf_put_eckey(struct sshbuf *buf, const EC_KEY *v)
175{
176	return sshbuf_put_ec(buf, EC_KEY_get0_public_key(v),
177	    EC_KEY_get0_group(v));
178}
179#endif /* OPENSSL_HAS_ECC */
180#endif /* WITH_OPENSSL */
181