1 /* $OpenBSD: sshbuf.c,v 1.8 2016/11/25 23:22:04 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 <signal.h>
23 #include <stdlib.h>
24 #include <stdio.h>
25 #include <string.h>
26
27 #include "ssherr.h"
28 #include "sshbuf.h"
29 #include "misc.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 sshbuf_free(buf->parent);
167 buf->parent = NULL;
168 /*
169 * If we are a parent with still-extant children, then don't free just
170 * yet. The last child's call to sshbuf_free should decrement our
171 * refcount to 0 and trigger the actual free.
172 */
173 buf->refcount--;
174 if (buf->refcount > 0)
175 return;
176 dont_free = buf->dont_free;
177 if (!buf->readonly) {
178 explicit_bzero(buf->d, buf->alloc);
179 free(buf->d);
180 }
181 explicit_bzero(buf, sizeof(*buf));
182 if (!dont_free)
183 free(buf);
184 }
185
186 void
sshbuf_reset(struct sshbuf * buf)187 sshbuf_reset(struct sshbuf *buf)
188 {
189 u_char *d;
190
191 if (buf->readonly || buf->refcount > 1) {
192 /* Nonsensical. Just make buffer appear empty */
193 buf->off = buf->size;
194 return;
195 }
196 if (sshbuf_check_sanity(buf) == 0)
197 explicit_bzero(buf->d, buf->alloc);
198 buf->off = buf->size = 0;
199 if (buf->alloc != SSHBUF_SIZE_INIT) {
200 if ((d = realloc(buf->d, SSHBUF_SIZE_INIT)) != NULL) {
201 buf->cd = buf->d = d;
202 buf->alloc = SSHBUF_SIZE_INIT;
203 }
204 }
205 }
206
207 size_t
sshbuf_max_size(const struct sshbuf * buf)208 sshbuf_max_size(const struct sshbuf *buf)
209 {
210 return buf->max_size;
211 }
212
213 size_t
sshbuf_alloc(const struct sshbuf * buf)214 sshbuf_alloc(const struct sshbuf *buf)
215 {
216 return buf->alloc;
217 }
218
219 const struct sshbuf *
sshbuf_parent(const struct sshbuf * buf)220 sshbuf_parent(const struct sshbuf *buf)
221 {
222 return buf->parent;
223 }
224
225 u_int
sshbuf_refcount(const struct sshbuf * buf)226 sshbuf_refcount(const struct sshbuf *buf)
227 {
228 return buf->refcount;
229 }
230
231 int
sshbuf_set_max_size(struct sshbuf * buf,size_t max_size)232 sshbuf_set_max_size(struct sshbuf *buf, size_t max_size)
233 {
234 size_t rlen;
235 u_char *dp;
236 int r;
237
238 SSHBUF_DBG(("set max buf = %p len = %zu", buf, max_size));
239 if ((r = sshbuf_check_sanity(buf)) != 0)
240 return r;
241 if (max_size == buf->max_size)
242 return 0;
243 if (buf->readonly || buf->refcount > 1)
244 return SSH_ERR_BUFFER_READ_ONLY;
245 if (max_size > SSHBUF_SIZE_MAX)
246 return SSH_ERR_NO_BUFFER_SPACE;
247 /* pack and realloc if necessary */
248 sshbuf_maybe_pack(buf, max_size < buf->size);
249 if (max_size < buf->alloc && max_size > buf->size) {
250 if (buf->size < SSHBUF_SIZE_INIT)
251 rlen = SSHBUF_SIZE_INIT;
252 else
253 rlen = ROUNDUP(buf->size, SSHBUF_SIZE_INC);
254 if (rlen > max_size)
255 rlen = max_size;
256 explicit_bzero(buf->d + buf->size, buf->alloc - buf->size);
257 SSHBUF_DBG(("new alloc = %zu", rlen));
258 if ((dp = realloc(buf->d, rlen)) == NULL)
259 return SSH_ERR_ALLOC_FAIL;
260 buf->cd = buf->d = dp;
261 buf->alloc = rlen;
262 }
263 SSHBUF_TELL("new-max");
264 if (max_size < buf->alloc)
265 return SSH_ERR_NO_BUFFER_SPACE;
266 buf->max_size = max_size;
267 return 0;
268 }
269
270 size_t
sshbuf_len(const struct sshbuf * buf)271 sshbuf_len(const struct sshbuf *buf)
272 {
273 if (sshbuf_check_sanity(buf) != 0)
274 return 0;
275 return buf->size - buf->off;
276 }
277
278 size_t
sshbuf_avail(const struct sshbuf * buf)279 sshbuf_avail(const struct sshbuf *buf)
280 {
281 if (sshbuf_check_sanity(buf) != 0 || buf->readonly || buf->refcount > 1)
282 return 0;
283 return buf->max_size - (buf->size - buf->off);
284 }
285
286 const u_char *
sshbuf_ptr(const struct sshbuf * buf)287 sshbuf_ptr(const struct sshbuf *buf)
288 {
289 if (sshbuf_check_sanity(buf) != 0)
290 return NULL;
291 return buf->cd + buf->off;
292 }
293
294 u_char *
sshbuf_mutable_ptr(const struct sshbuf * buf)295 sshbuf_mutable_ptr(const struct sshbuf *buf)
296 {
297 if (sshbuf_check_sanity(buf) != 0 || buf->readonly || buf->refcount > 1)
298 return NULL;
299 return buf->d + buf->off;
300 }
301
302 int
sshbuf_check_reserve(const struct sshbuf * buf,size_t len)303 sshbuf_check_reserve(const struct sshbuf *buf, size_t len)
304 {
305 int r;
306
307 if ((r = sshbuf_check_sanity(buf)) != 0)
308 return r;
309 if (buf->readonly || buf->refcount > 1)
310 return SSH_ERR_BUFFER_READ_ONLY;
311 SSHBUF_TELL("check");
312 /* Check that len is reasonable and that max_size + available < len */
313 if (len > buf->max_size || buf->max_size - len < buf->size - buf->off)
314 return SSH_ERR_NO_BUFFER_SPACE;
315 return 0;
316 }
317
318 int
sshbuf_allocate(struct sshbuf * buf,size_t len)319 sshbuf_allocate(struct sshbuf *buf, size_t len)
320 {
321 size_t rlen, need;
322 u_char *dp;
323 int r;
324
325 SSHBUF_DBG(("allocate buf = %p len = %zu", buf, len));
326 if ((r = sshbuf_check_reserve(buf, len)) != 0)
327 return r;
328 /*
329 * If the requested allocation appended would push us past max_size
330 * then pack the buffer, zeroing buf->off.
331 */
332 sshbuf_maybe_pack(buf, buf->size + len > buf->max_size);
333 SSHBUF_TELL("allocate");
334 if (len + buf->size <= buf->alloc)
335 return 0; /* already have it. */
336
337 /*
338 * Prefer to alloc in SSHBUF_SIZE_INC units, but
339 * allocate less if doing so would overflow max_size.
340 */
341 need = len + buf->size - buf->alloc;
342 rlen = ROUNDUP(buf->alloc + need, SSHBUF_SIZE_INC);
343 SSHBUF_DBG(("need %zu initial rlen %zu", need, rlen));
344 if (rlen > buf->max_size)
345 rlen = buf->alloc + need;
346 SSHBUF_DBG(("adjusted rlen %zu", rlen));
347 if ((dp = realloc(buf->d, rlen)) == NULL) {
348 SSHBUF_DBG(("realloc fail"));
349 return SSH_ERR_ALLOC_FAIL;
350 }
351 buf->alloc = rlen;
352 buf->cd = buf->d = dp;
353 if ((r = sshbuf_check_reserve(buf, len)) < 0) {
354 /* shouldn't fail */
355 return r;
356 }
357 SSHBUF_TELL("done");
358 return 0;
359 }
360
361 int
sshbuf_reserve(struct sshbuf * buf,size_t len,u_char ** dpp)362 sshbuf_reserve(struct sshbuf *buf, size_t len, u_char **dpp)
363 {
364 u_char *dp;
365 int r;
366
367 if (dpp != NULL)
368 *dpp = NULL;
369
370 SSHBUF_DBG(("reserve buf = %p len = %zu", buf, len));
371 if ((r = sshbuf_allocate(buf, len)) != 0)
372 return r;
373
374 dp = buf->d + buf->size;
375 buf->size += len;
376 if (dpp != NULL)
377 *dpp = dp;
378 return 0;
379 }
380
381 int
sshbuf_consume(struct sshbuf * buf,size_t len)382 sshbuf_consume(struct sshbuf *buf, size_t len)
383 {
384 int r;
385
386 SSHBUF_DBG(("len = %zu", len));
387 if ((r = sshbuf_check_sanity(buf)) != 0)
388 return r;
389 if (len == 0)
390 return 0;
391 if (len > sshbuf_len(buf))
392 return SSH_ERR_MESSAGE_INCOMPLETE;
393 buf->off += len;
394 SSHBUF_TELL("done");
395 return 0;
396 }
397
398 int
sshbuf_consume_end(struct sshbuf * buf,size_t len)399 sshbuf_consume_end(struct sshbuf *buf, size_t len)
400 {
401 int r;
402
403 SSHBUF_DBG(("len = %zu", len));
404 if ((r = sshbuf_check_sanity(buf)) != 0)
405 return r;
406 if (len == 0)
407 return 0;
408 if (len > sshbuf_len(buf))
409 return SSH_ERR_MESSAGE_INCOMPLETE;
410 buf->size -= len;
411 SSHBUF_TELL("done");
412 return 0;
413 }
414
415