Coverage Report

Created: 2025-06-20 06:24

/src/openssh/kex-names.c
Line
Count
Source (jump to first uncovered line)
1
/* $OpenBSD: kex-names.c,v 1.4 2024/09/09 02:39:57 djm Exp $ */
2
/*
3
 * Copyright (c) 2000, 2001 Markus Friedl.  All rights reserved.
4
 *
5
 * Redistribution and use in source and binary forms, with or without
6
 * modification, are permitted provided that the following conditions
7
 * are met:
8
 * 1. Redistributions of source code must retain the above copyright
9
 *    notice, this list of conditions and the following disclaimer.
10
 * 2. Redistributions in binary form must reproduce the above copyright
11
 *    notice, this list of conditions and the following disclaimer in the
12
 *    documentation and/or other materials provided with the distribution.
13
 *
14
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
15
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
16
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
17
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
18
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
19
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
20
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
21
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
23
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24
 */
25
26
#include "includes.h"
27
28
#include <stdio.h>
29
#include <stdlib.h>
30
#include <string.h>
31
#include <unistd.h>
32
#include <signal.h>
33
34
#ifdef WITH_OPENSSL
35
#include <openssl/crypto.h>
36
#include <openssl/evp.h>
37
#endif
38
39
#include "kex.h"
40
#include "log.h"
41
#include "match.h"
42
#include "digest.h"
43
#include "misc.h"
44
45
#include "ssherr.h"
46
#include "xmalloc.h"
47
48
struct kexalg {
49
  char *name;
50
  u_int type;
51
  int ec_nid;
52
  int hash_alg;
53
};
54
static const struct kexalg kexalgs[] = {
55
#ifdef WITH_OPENSSL
56
  { KEX_DH1, KEX_DH_GRP1_SHA1, 0, SSH_DIGEST_SHA1 },
57
  { KEX_DH14_SHA1, KEX_DH_GRP14_SHA1, 0, SSH_DIGEST_SHA1 },
58
  { KEX_DH14_SHA256, KEX_DH_GRP14_SHA256, 0, SSH_DIGEST_SHA256 },
59
  { KEX_DH16_SHA512, KEX_DH_GRP16_SHA512, 0, SSH_DIGEST_SHA512 },
60
  { KEX_DH18_SHA512, KEX_DH_GRP18_SHA512, 0, SSH_DIGEST_SHA512 },
61
  { KEX_DHGEX_SHA1, KEX_DH_GEX_SHA1, 0, SSH_DIGEST_SHA1 },
62
#ifdef HAVE_EVP_SHA256
63
  { KEX_DHGEX_SHA256, KEX_DH_GEX_SHA256, 0, SSH_DIGEST_SHA256 },
64
#endif /* HAVE_EVP_SHA256 */
65
#ifdef OPENSSL_HAS_ECC
66
  { KEX_ECDH_SHA2_NISTP256, KEX_ECDH_SHA2,
67
      NID_X9_62_prime256v1, SSH_DIGEST_SHA256 },
68
  { KEX_ECDH_SHA2_NISTP384, KEX_ECDH_SHA2, NID_secp384r1,
69
      SSH_DIGEST_SHA384 },
70
# ifdef OPENSSL_HAS_NISTP521
71
  { KEX_ECDH_SHA2_NISTP521, KEX_ECDH_SHA2, NID_secp521r1,
72
      SSH_DIGEST_SHA512 },
73
# endif /* OPENSSL_HAS_NISTP521 */
74
#endif /* OPENSSL_HAS_ECC */
75
#endif /* WITH_OPENSSL */
76
#if defined(HAVE_EVP_SHA256) || !defined(WITH_OPENSSL)
77
  { KEX_CURVE25519_SHA256, KEX_C25519_SHA256, 0, SSH_DIGEST_SHA256 },
78
  { KEX_CURVE25519_SHA256_OLD, KEX_C25519_SHA256, 0, SSH_DIGEST_SHA256 },
79
#ifdef USE_SNTRUP761X25519
80
  { KEX_SNTRUP761X25519_SHA512, KEX_KEM_SNTRUP761X25519_SHA512, 0,
81
      SSH_DIGEST_SHA512 },
82
  { KEX_SNTRUP761X25519_SHA512_OLD, KEX_KEM_SNTRUP761X25519_SHA512, 0,
83
      SSH_DIGEST_SHA512 },
84
#endif
85
#ifdef USE_MLKEM768X25519
86
  { KEX_MLKEM768X25519_SHA256, KEX_KEM_MLKEM768X25519_SHA256, 0,
87
      SSH_DIGEST_SHA256 },
88
#endif
89
#endif /* HAVE_EVP_SHA256 || !WITH_OPENSSL */
90
  { NULL, 0, -1, -1},
91
};
92
93
char *
94
kex_alg_list(char sep)
95
0
{
96
0
  char *ret = NULL, *tmp;
97
0
  size_t nlen, rlen = 0;
98
0
  const struct kexalg *k;
99
100
0
  for (k = kexalgs; k->name != NULL; k++) {
101
0
    if (ret != NULL)
102
0
      ret[rlen++] = sep;
103
0
    nlen = strlen(k->name);
104
0
    if ((tmp = realloc(ret, rlen + nlen + 2)) == NULL) {
105
0
      free(ret);
106
0
      return NULL;
107
0
    }
108
0
    ret = tmp;
109
0
    memcpy(ret + rlen, k->name, nlen + 1);
110
0
    rlen += nlen;
111
0
  }
112
0
  return ret;
113
0
}
114
115
static const struct kexalg *
116
kex_alg_by_name(const char *name)
117
85.4k
{
118
85.4k
  const struct kexalg *k;
119
120
718k
  for (k = kexalgs; k->name != NULL; k++) {
121
718k
    if (strcmp(k->name, name) == 0)
122
85.3k
      return k;
123
718k
  }
124
90
  return NULL;
125
85.4k
}
126
127
int
128
kex_name_valid(const char *name)
129
21.4k
{
130
21.4k
  return kex_alg_by_name(name) != NULL;
131
21.4k
}
132
133
u_int
134
kex_type_from_name(const char *name)
135
21.3k
{
136
21.3k
  const struct kexalg *k;
137
138
21.3k
  if ((k = kex_alg_by_name(name)) == NULL)
139
0
    return 0;
140
21.3k
  return k->type;
141
21.3k
}
142
143
int
144
kex_hash_from_name(const char *name)
145
21.3k
{
146
21.3k
  const struct kexalg *k;
147
148
21.3k
  if ((k = kex_alg_by_name(name)) == NULL)
149
0
    return -1;
150
21.3k
  return k->hash_alg;
151
21.3k
}
152
153
int
154
kex_nid_from_name(const char *name)
155
21.3k
{
156
21.3k
  const struct kexalg *k;
157
158
21.3k
  if ((k = kex_alg_by_name(name)) == NULL)
159
0
    return -1;
160
21.3k
  return k->ec_nid;
161
21.3k
}
162
163
/* Validate KEX method name list */
164
int
165
kex_names_valid(const char *names)
166
0
{
167
0
  char *s, *cp, *p;
168
169
0
  if (names == NULL || strcmp(names, "") == 0)
170
0
    return 0;
171
0
  if ((s = cp = strdup(names)) == NULL)
172
0
    return 0;
173
0
  for ((p = strsep(&cp, ",")); p && *p != '\0';
174
0
      (p = strsep(&cp, ","))) {
175
0
    if (kex_alg_by_name(p) == NULL) {
176
0
      error("Unsupported KEX algorithm \"%.100s\"", p);
177
0
      free(s);
178
0
      return 0;
179
0
    }
180
0
  }
181
0
  debug3("kex names ok: [%s]", names);
182
0
  free(s);
183
0
  return 1;
184
0
}
185
186
/* returns non-zero if proposal contains any algorithm from algs */
187
int
188
kex_has_any_alg(const char *proposal, const char *algs)
189
581k
{
190
581k
  char *cp;
191
192
581k
  if ((cp = match_list(proposal, algs, NULL)) == NULL)
193
563k
    return 0;
194
17.5k
  free(cp);
195
17.5k
  return 1;
196
581k
}
197
198
/*
199
 * Concatenate algorithm names, avoiding duplicates in the process.
200
 * Caller must free returned string.
201
 */
202
char *
203
kex_names_cat(const char *a, const char *b)
204
179k
{
205
179k
  char *ret = NULL, *tmp = NULL, *cp, *p;
206
179k
  size_t len;
207
208
179k
  if (a == NULL || *a == '\0')
209
0
    return strdup(b);
210
179k
  if (b == NULL || *b == '\0')
211
0
    return strdup(a);
212
179k
  if (strlen(b) > 1024*1024)
213
0
    return NULL;
214
179k
  len = strlen(a) + strlen(b) + 2;
215
179k
  if ((tmp = cp = strdup(b)) == NULL ||
216
179k
      (ret = calloc(1, len)) == NULL) {
217
0
    free(tmp);
218
0
    return NULL;
219
0
  }
220
179k
  strlcpy(ret, a, len);
221
537k
  for ((p = strsep(&cp, ",")); p && *p != '\0'; (p = strsep(&cp, ","))) {
222
358k
    if (kex_has_any_alg(ret, p))
223
0
      continue; /* Algorithm already present */
224
358k
    if (strlcat(ret, ",", len) >= len ||
225
358k
        strlcat(ret, p, len) >= len) {
226
0
      free(tmp);
227
0
      free(ret);
228
0
      return NULL; /* Shouldn't happen */
229
0
    }
230
358k
  }
231
179k
  free(tmp);
232
179k
  return ret;
233
179k
}
234
235
/*
236
 * Assemble a list of algorithms from a default list and a string from a
237
 * configuration file. The user-provided string may begin with '+' to
238
 * indicate that it should be appended to the default, '-' that the
239
 * specified names should be removed, or '^' that they should be placed
240
 * at the head.
241
 */
242
int
243
kex_assemble_names(char **listp, const char *def, const char *all)
244
0
{
245
0
  char *cp, *tmp, *patterns;
246
0
  char *list = NULL, *ret = NULL, *matching = NULL, *opatterns = NULL;
247
0
  int r = SSH_ERR_INTERNAL_ERROR;
248
249
0
  if (listp == NULL || def == NULL || all == NULL)
250
0
    return SSH_ERR_INVALID_ARGUMENT;
251
252
0
  if (*listp == NULL || **listp == '\0') {
253
0
    if ((*listp = strdup(def)) == NULL)
254
0
      return SSH_ERR_ALLOC_FAIL;
255
0
    return 0;
256
0
  }
257
258
0
  list = *listp;
259
0
  *listp = NULL;
260
0
  if (*list == '+') {
261
    /* Append names to default list */
262
0
    if ((tmp = kex_names_cat(def, list + 1)) == NULL) {
263
0
      r = SSH_ERR_ALLOC_FAIL;
264
0
      goto fail;
265
0
    }
266
0
    free(list);
267
0
    list = tmp;
268
0
  } else if (*list == '-') {
269
    /* Remove names from default list */
270
0
    if ((*listp = match_filter_denylist(def, list + 1)) == NULL) {
271
0
      r = SSH_ERR_ALLOC_FAIL;
272
0
      goto fail;
273
0
    }
274
0
    free(list);
275
    /* filtering has already been done */
276
0
    return 0;
277
0
  } else if (*list == '^') {
278
    /* Place names at head of default list */
279
0
    if ((tmp = kex_names_cat(list + 1, def)) == NULL) {
280
0
      r = SSH_ERR_ALLOC_FAIL;
281
0
      goto fail;
282
0
    }
283
0
    free(list);
284
0
    list = tmp;
285
0
  } else {
286
    /* Explicit list, overrides default - just use "list" as is */
287
0
  }
288
289
  /*
290
   * The supplied names may be a pattern-list. For the -list case,
291
   * the patterns are applied above. For the +list and explicit list
292
   * cases we need to do it now.
293
   */
294
0
  ret = NULL;
295
0
  if ((patterns = opatterns = strdup(list)) == NULL) {
296
0
    r = SSH_ERR_ALLOC_FAIL;
297
0
    goto fail;
298
0
  }
299
  /* Apply positive (i.e. non-negated) patterns from the list */
300
0
  while ((cp = strsep(&patterns, ",")) != NULL) {
301
0
    if (*cp == '!') {
302
      /* negated matches are not supported here */
303
0
      r = SSH_ERR_INVALID_ARGUMENT;
304
0
      goto fail;
305
0
    }
306
0
    free(matching);
307
0
    if ((matching = match_filter_allowlist(all, cp)) == NULL) {
308
0
      r = SSH_ERR_ALLOC_FAIL;
309
0
      goto fail;
310
0
    }
311
0
    if ((tmp = kex_names_cat(ret, matching)) == NULL) {
312
0
      r = SSH_ERR_ALLOC_FAIL;
313
0
      goto fail;
314
0
    }
315
0
    free(ret);
316
0
    ret = tmp;
317
0
  }
318
0
  if (ret == NULL || *ret == '\0') {
319
    /* An empty name-list is an error */
320
    /* XXX better error code? */
321
0
    r = SSH_ERR_INVALID_ARGUMENT;
322
0
    goto fail;
323
0
  }
324
325
  /* success */
326
0
  *listp = ret;
327
0
  ret = NULL;
328
0
  r = 0;
329
330
0
 fail:
331
0
  free(matching);
332
0
  free(opatterns);
333
0
  free(list);
334
0
  free(ret);
335
0
  return r;
336
0
}