1 /* $OpenBSD: sshbuf.c,v 1.4 2015/10/05 17:11:21 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/param.h> /* roundup */
22 #include <sys/types.h>
23 #include <signal.h>
24 #include <stdlib.h>
25 #include <stdio.h>
26 #include <string.h>
27
28 #include "ssherr.h"
29 #include "sshbuf.h"
30
31 static inline int
sshbuf_check_sanity(const struct sshbuf * buf)32 sshbuf_check_sanity(const struct sshbuf *buf)
33 {
34 SSHBUF_TELL("sanity");
35 if (__predict_false(buf == NULL ||
36 (!buf->readonly && buf->d != buf->cd) ||
37 buf->refcount < 1 || buf->refcount > SSHBUF_REFS_MAX ||
38 buf->cd == NULL ||
39 (buf->dont_free && (buf->readonly || buf->parent != NULL)) ||
40 buf->max_size > SSHBUF_SIZE_MAX ||
41 buf->alloc > buf->max_size ||
42 buf->size > buf->alloc ||
43 buf->off > buf->size)) {
44 /* Do not try to recover from corrupted buffer internals */
45 SSHBUF_DBG(("SSH_ERR_INTERNAL_ERROR"));
46 signal(SIGSEGV, SIG_DFL);
47 raise(SIGSEGV);
48 return SSH_ERR_INTERNAL_ERROR;
49 }
50 return 0;
51 }
52
53 static void
sshbuf_maybe_pack(struct sshbuf * buf,int force)54 sshbuf_maybe_pack(struct sshbuf *buf, int force)
55 {
56 SSHBUF_DBG(("force %d", force));
57 SSHBUF_TELL("pre-pack");
58 if (buf->off == 0 || buf->readonly || buf->refcount > 1)
59 return;
60 if (force ||
61 (buf->off >= SSHBUF_PACK_MIN && buf->off >= buf->size / 2)) {
62 memmove(buf->d, buf->d + buf->off, buf->size - buf->off);
63 buf->size -= buf->off;
64 buf->off = 0;
65 SSHBUF_TELL("packed");
66 }
67 }
68
69 struct sshbuf *
sshbuf_new(void)70 sshbuf_new(void)
71 {
72 struct sshbuf *ret;
73
74 if ((ret = calloc(sizeof(*ret), 1)) == NULL)
75 return NULL;
76 ret->alloc = SSHBUF_SIZE_INIT;
77 ret->max_size = SSHBUF_SIZE_MAX;
78 ret->readonly = 0;
79 ret->refcount = 1;
80 ret->parent = NULL;
81 if ((ret->cd = ret->d = calloc(1, ret->alloc)) == NULL) {
82 free(ret);
83 return NULL;
84 }
85 return ret;
86 }
87
88 struct sshbuf *
sshbuf_from(const void * blob,size_t len)89 sshbuf_from(const void *blob, size_t len)
90 {
91 struct sshbuf *ret;
92
93 if (blob == NULL || len > SSHBUF_SIZE_MAX ||
94 (ret = calloc(sizeof(*ret), 1)) == NULL)
95 return NULL;
96 ret->alloc = ret->size = ret->max_size = len;
97 ret->readonly = 1;
98 ret->refcount = 1;
99 ret->parent = NULL;
100 ret->cd = blob;
101 ret->d = NULL;
102 return ret;
103 }
104
105 int
sshbuf_set_parent(struct sshbuf * child,struct sshbuf * parent)106 sshbuf_set_parent(struct sshbuf *child, struct sshbuf *parent)
107 {
108 int r;
109
110 if ((r = sshbuf_check_sanity(child)) != 0 ||
111 (r = sshbuf_check_sanity(parent)) != 0)
112 return r;
113 child->parent = parent;
114 child->parent->refcount++;
115 return 0;
116 }
117
118 struct sshbuf *
sshbuf_fromb(struct sshbuf * buf)119 sshbuf_fromb(struct sshbuf *buf)
120 {
121 struct sshbuf *ret;
122
123 if (sshbuf_check_sanity(buf) != 0)
124 return NULL;
125 if ((ret = sshbuf_from(sshbuf_ptr(buf), sshbuf_len(buf))) == NULL)
126 return NULL;
127 if (sshbuf_set_parent(ret, buf) != 0) {
128 sshbuf_free(ret);
129 return NULL;
130 }
131 return ret;
132 }
133
134 void
sshbuf_init(struct sshbuf * ret)135 sshbuf_init(struct sshbuf *ret)
136 {
137 explicit_bzero(ret, sizeof(*ret));
138 ret->alloc = SSHBUF_SIZE_INIT;
139 ret->max_size = SSHBUF_SIZE_MAX;
140 ret->readonly = 0;
141 ret->dont_free = 1;
142 ret->refcount = 1;
143 if ((ret->cd = ret->d = calloc(1, ret->alloc)) == NULL)
144 ret->alloc = 0;
145 }
146
147 void
sshbuf_free(struct sshbuf * buf)148 sshbuf_free(struct sshbuf *buf)
149 {
150 int dont_free = 0;
151
152 if (buf == NULL)
153 return;
154 /*
155 * The following will leak on insane buffers, but this is the safest
156 * course of action - an invalid pointer or already-freed pointer may
157 * have been passed to us and continuing to scribble over memory would
158 * be bad.
159 */
160 if (sshbuf_check_sanity(buf) != 0)
161 return;
162 /*
163 * If we are a child, the free our parent to decrement its reference
164 * count and possibly free it.
165 */
166 if (buf->parent != NULL) {
167 sshbuf_free(buf->parent);
168 buf->parent = NULL;
169 }
170 /*
171 * If we are a parent with still-extant children, then don't free just
172 * yet. The last child's call to sshbuf_free should decrement our
173 * refcount to 0 and trigger the actual free.
174 */
175 buf->refcount--;
176 if (buf->refcount > 0)
177 return;
178 dont_free = buf->dont_free;
179 if (!buf->readonly) {
180 explicit_bzero(buf->d, buf->alloc);
181 free(buf->d);
182 }
183 explicit_bzero(buf, sizeof(*buf));
184 if (!dont_free)
185 free(buf);
186 }
187
188 void
sshbuf_reset(struct sshbuf * buf)189 sshbuf_reset(struct sshbuf *buf)
190 {
191 u_char *d;
192
193 if (buf->readonly || buf->refcount > 1) {
194 /* Nonsensical. Just make buffer appear empty */
195 buf->off = buf->size;
196 return;
197 }
198 if (sshbuf_check_sanity(buf) == 0)
199 explicit_bzero(buf->d, buf->alloc);
200 buf->off = buf->size = 0;
201 if (buf->alloc != SSHBUF_SIZE_INIT) {
202 if ((d = realloc(buf->d, SSHBUF_SIZE_INIT)) != NULL) {
203 buf->cd = buf->d = d;
204 buf->alloc = SSHBUF_SIZE_INIT;
205 }
206 }
207 }
208
209 size_t
sshbuf_max_size(const struct sshbuf * buf)210 sshbuf_max_size(const struct sshbuf *buf)
211 {
212 return buf->max_size;
213 }
214
215 size_t
sshbuf_alloc(const struct sshbuf * buf)216 sshbuf_alloc(const struct sshbuf *buf)
217 {
218 return buf->alloc;
219 }
220
221 const struct sshbuf *
sshbuf_parent(const struct sshbuf * buf)222 sshbuf_parent(const struct sshbuf *buf)
223 {
224 return buf->parent;
225 }
226
227 u_int
sshbuf_refcount(const struct sshbuf * buf)228 sshbuf_refcount(const struct sshbuf *buf)
229 {
230 return buf->refcount;
231 }
232
233 int
sshbuf_set_max_size(struct sshbuf * buf,size_t max_size)234 sshbuf_set_max_size(struct sshbuf *buf, size_t max_size)
235 {
236 size_t rlen;
237 u_char *dp;
238 int r;
239
240 SSHBUF_DBG(("set max buf = %p len = %zu", buf, max_size));
241 if ((r = sshbuf_check_sanity(buf)) != 0)
242 return r;
243 if (max_size == buf->max_size)
244 return 0;
245 if (buf->readonly || buf->refcount > 1)
246 return SSH_ERR_BUFFER_READ_ONLY;
247 if (max_size > SSHBUF_SIZE_MAX)
248 return SSH_ERR_NO_BUFFER_SPACE;
249 /* pack and realloc if necessary */
250 sshbuf_maybe_pack(buf, max_size < buf->size);
251 if (max_size < buf->alloc && max_size > buf->size) {
252 if (buf->size < SSHBUF_SIZE_INIT)
253 rlen = SSHBUF_SIZE_INIT;
254 else
255 rlen = roundup(buf->size, SSHBUF_SIZE_INC);
256 if (rlen > max_size)
257 rlen = max_size;
258 explicit_bzero(buf->d + buf->size, buf->alloc - buf->size);
259 SSHBUF_DBG(("new alloc = %zu", rlen));
260 if ((dp = realloc(buf->d, rlen)) == NULL)
261 return SSH_ERR_ALLOC_FAIL;
262 buf->cd = buf->d = dp;
263 buf->alloc = rlen;
264 }
265 SSHBUF_TELL("new-max");
266 if (max_size < buf->alloc)
267 return SSH_ERR_NO_BUFFER_SPACE;
268 buf->max_size = max_size;
269 return 0;
270 }
271
272 size_t
sshbuf_len(const struct sshbuf * buf)273 sshbuf_len(const struct sshbuf *buf)
274 {
275 if (sshbuf_check_sanity(buf) != 0)
276 return 0;
277 return buf->size - buf->off;
278 }
279
280 size_t
sshbuf_avail(const struct sshbuf * buf)281 sshbuf_avail(const struct sshbuf *buf)
282 {
283 if (sshbuf_check_sanity(buf) != 0 || buf->readonly || buf->refcount > 1)
284 return 0;
285 return buf->max_size - (buf->size - buf->off);
286 }
287
288 const u_char *
sshbuf_ptr(const struct sshbuf * buf)289 sshbuf_ptr(const struct sshbuf *buf)
290 {
291 if (sshbuf_check_sanity(buf) != 0)
292 return NULL;
293 return buf->cd + buf->off;
294 }
295
296 u_char *
sshbuf_mutable_ptr(const struct sshbuf * buf)297 sshbuf_mutable_ptr(const struct sshbuf *buf)
298 {
299 if (sshbuf_check_sanity(buf) != 0 || buf->readonly || buf->refcount > 1)
300 return NULL;
301 return buf->d + buf->off;
302 }
303
304 int
sshbuf_check_reserve(const struct sshbuf * buf,size_t len)305 sshbuf_check_reserve(const struct sshbuf *buf, size_t len)
306 {
307 int r;
308
309 if ((r = sshbuf_check_sanity(buf)) != 0)
310 return r;
311 if (buf->readonly || buf->refcount > 1)
312 return SSH_ERR_BUFFER_READ_ONLY;
313 SSHBUF_TELL("check");
314 /* Check that len is reasonable and that max_size + available < len */
315 if (len > buf->max_size || buf->max_size - len < buf->size - buf->off)
316 return SSH_ERR_NO_BUFFER_SPACE;
317 return 0;
318 }
319
320 int
sshbuf_reserve(struct sshbuf * buf,size_t len,u_char ** dpp)321 sshbuf_reserve(struct sshbuf *buf, size_t len, u_char **dpp)
322 {
323 size_t rlen, need;
324 u_char *dp;
325 int r;
326
327 if (dpp != NULL)
328 *dpp = NULL;
329
330 SSHBUF_DBG(("reserve buf = %p len = %zu", buf, len));
331 if ((r = sshbuf_check_reserve(buf, len)) != 0)
332 return r;
333 /*
334 * If the requested allocation appended would push us past max_size
335 * then pack the buffer, zeroing buf->off.
336 */
337 sshbuf_maybe_pack(buf, buf->size + len > buf->max_size);
338 SSHBUF_TELL("reserve");
339 if (len + buf->size > buf->alloc) {
340 /*
341 * Prefer to alloc in SSHBUF_SIZE_INC units, but
342 * allocate less if doing so would overflow max_size.
343 */
344 need = len + buf->size - buf->alloc;
345 rlen = roundup(buf->alloc + need, SSHBUF_SIZE_INC);
346 SSHBUF_DBG(("need %zu initial rlen %zu", need, rlen));
347 if (rlen > buf->max_size)
348 rlen = buf->alloc + need;
349 SSHBUF_DBG(("adjusted rlen %zu", rlen));
350 if ((dp = realloc(buf->d, rlen)) == NULL) {
351 SSHBUF_DBG(("realloc fail"));
352 if (dpp != NULL)
353 *dpp = NULL;
354 return SSH_ERR_ALLOC_FAIL;
355 }
356 buf->alloc = rlen;
357 buf->cd = buf->d = dp;
358 if ((r = sshbuf_check_reserve(buf, len)) < 0) {
359 /* shouldn't fail */
360 if (dpp != NULL)
361 *dpp = NULL;
362 return r;
363 }
364 }
365 dp = buf->d + buf->size;
366 buf->size += len;
367 SSHBUF_TELL("done");
368 if (dpp != NULL)
369 *dpp = dp;
370 return 0;
371 }
372
373 int
sshbuf_consume(struct sshbuf * buf,size_t len)374 sshbuf_consume(struct sshbuf *buf, size_t len)
375 {
376 int r;
377
378 SSHBUF_DBG(("len = %zu", len));
379 if ((r = sshbuf_check_sanity(buf)) != 0)
380 return r;
381 if (len == 0)
382 return 0;
383 if (len > sshbuf_len(buf))
384 return SSH_ERR_MESSAGE_INCOMPLETE;
385 buf->off += len;
386 SSHBUF_TELL("done");
387 return 0;
388 }
389
390 int
sshbuf_consume_end(struct sshbuf * buf,size_t len)391 sshbuf_consume_end(struct sshbuf *buf, size_t len)
392 {
393 int r;
394
395 SSHBUF_DBG(("len = %zu", len));
396 if ((r = sshbuf_check_sanity(buf)) != 0)
397 return r;
398 if (len == 0)
399 return 0;
400 if (len > sshbuf_len(buf))
401 return SSH_ERR_MESSAGE_INCOMPLETE;
402 buf->size -= len;
403 SSHBUF_TELL("done");
404 return 0;
405 }
406
407