1 /* $OpenBSD: sshbuf.c,v 1.12 2018/07/09 21:56:06 markus 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 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->max_size > SSHBUF_SIZE_MAX || 40 buf->alloc > buf->max_size || 41 buf->size > buf->alloc || 42 buf->off > buf->size)) { 43 /* Do not try to recover from corrupted buffer internals */ 44 SSHBUF_DBG(("SSH_ERR_INTERNAL_ERROR")); 45 signal(SIGSEGV, SIG_DFL); 46 raise(SIGSEGV); 47 return SSH_ERR_INTERNAL_ERROR; 48 } 49 return 0; 50 } 51 52 static void 53 sshbuf_maybe_pack(struct sshbuf *buf, int force) 54 { 55 SSHBUF_DBG(("force %d", force)); 56 SSHBUF_TELL("pre-pack"); 57 if (buf->off == 0 || buf->readonly || buf->refcount > 1) 58 return; 59 if (force || 60 (buf->off >= SSHBUF_PACK_MIN && buf->off >= buf->size / 2)) { 61 memmove(buf->d, buf->d + buf->off, buf->size - buf->off); 62 buf->size -= buf->off; 63 buf->off = 0; 64 SSHBUF_TELL("packed"); 65 } 66 } 67 68 struct sshbuf * 69 sshbuf_new(void) 70 { 71 struct sshbuf *ret; 72 73 if ((ret = calloc(sizeof(*ret), 1)) == NULL) 74 return NULL; 75 ret->alloc = SSHBUF_SIZE_INIT; 76 ret->max_size = SSHBUF_SIZE_MAX; 77 ret->readonly = 0; 78 ret->refcount = 1; 79 ret->parent = NULL; 80 if ((ret->cd = ret->d = calloc(1, ret->alloc)) == NULL) { 81 free(ret); 82 return NULL; 83 } 84 return ret; 85 } 86 87 struct sshbuf * 88 sshbuf_from(const void *blob, size_t len) 89 { 90 struct sshbuf *ret; 91 92 if (blob == NULL || len > SSHBUF_SIZE_MAX || 93 (ret = calloc(sizeof(*ret), 1)) == NULL) 94 return NULL; 95 ret->alloc = ret->size = ret->max_size = len; 96 ret->readonly = 1; 97 ret->refcount = 1; 98 ret->parent = NULL; 99 ret->cd = blob; 100 ret->d = NULL; 101 return ret; 102 } 103 104 int 105 sshbuf_set_parent(struct sshbuf *child, struct sshbuf *parent) 106 { 107 int r; 108 109 if ((r = sshbuf_check_sanity(child)) != 0 || 110 (r = sshbuf_check_sanity(parent)) != 0) 111 return r; 112 child->parent = parent; 113 child->parent->refcount++; 114 return 0; 115 } 116 117 struct sshbuf * 118 sshbuf_fromb(struct sshbuf *buf) 119 { 120 struct sshbuf *ret; 121 122 if (sshbuf_check_sanity(buf) != 0) 123 return NULL; 124 if ((ret = sshbuf_from(sshbuf_ptr(buf), sshbuf_len(buf))) == NULL) 125 return NULL; 126 if (sshbuf_set_parent(ret, buf) != 0) { 127 sshbuf_free(ret); 128 return NULL; 129 } 130 return ret; 131 } 132 133 void 134 sshbuf_free(struct sshbuf *buf) 135 { 136 if (buf == NULL) 137 return; 138 /* 139 * The following will leak on insane buffers, but this is the safest 140 * course of action - an invalid pointer or already-freed pointer may 141 * have been passed to us and continuing to scribble over memory would 142 * be bad. 143 */ 144 if (sshbuf_check_sanity(buf) != 0) 145 return; 146 /* 147 * If we are a child, the free our parent to decrement its reference 148 * count and possibly free it. 149 */ 150 sshbuf_free(buf->parent); 151 buf->parent = NULL; 152 /* 153 * If we are a parent with still-extant children, then don't free just 154 * yet. The last child's call to sshbuf_free should decrement our 155 * refcount to 0 and trigger the actual free. 156 */ 157 buf->refcount--; 158 if (buf->refcount > 0) 159 return; 160 if (!buf->readonly) { 161 explicit_bzero(buf->d, buf->alloc); 162 free(buf->d); 163 } 164 explicit_bzero(buf, sizeof(*buf)); 165 free(buf); 166 } 167 168 void 169 sshbuf_reset(struct sshbuf *buf) 170 { 171 u_char *d; 172 173 if (buf->readonly || buf->refcount > 1) { 174 /* Nonsensical. Just make buffer appear empty */ 175 buf->off = buf->size; 176 return; 177 } 178 (void) sshbuf_check_sanity(buf); 179 buf->off = buf->size = 0; 180 if (buf->alloc != SSHBUF_SIZE_INIT) { 181 if ((d = recallocarray(buf->d, buf->alloc, SSHBUF_SIZE_INIT, 182 1)) != NULL) { 183 buf->cd = buf->d = d; 184 buf->alloc = SSHBUF_SIZE_INIT; 185 } 186 } 187 explicit_bzero(buf->d, SSHBUF_SIZE_INIT); 188 } 189 190 size_t 191 sshbuf_max_size(const struct sshbuf *buf) 192 { 193 return buf->max_size; 194 } 195 196 size_t 197 sshbuf_alloc(const struct sshbuf *buf) 198 { 199 return buf->alloc; 200 } 201 202 const struct sshbuf * 203 sshbuf_parent(const struct sshbuf *buf) 204 { 205 return buf->parent; 206 } 207 208 u_int 209 sshbuf_refcount(const struct sshbuf *buf) 210 { 211 return buf->refcount; 212 } 213 214 int 215 sshbuf_set_max_size(struct sshbuf *buf, size_t max_size) 216 { 217 size_t rlen; 218 u_char *dp; 219 int r; 220 221 SSHBUF_DBG(("set max buf = %p len = %zu", buf, max_size)); 222 if ((r = sshbuf_check_sanity(buf)) != 0) 223 return r; 224 if (max_size == buf->max_size) 225 return 0; 226 if (buf->readonly || buf->refcount > 1) 227 return SSH_ERR_BUFFER_READ_ONLY; 228 if (max_size > SSHBUF_SIZE_MAX) 229 return SSH_ERR_NO_BUFFER_SPACE; 230 /* pack and realloc if necessary */ 231 sshbuf_maybe_pack(buf, max_size < buf->size); 232 if (max_size < buf->alloc && max_size > buf->size) { 233 if (buf->size < SSHBUF_SIZE_INIT) 234 rlen = SSHBUF_SIZE_INIT; 235 else 236 rlen = ROUNDUP(buf->size, SSHBUF_SIZE_INC); 237 if (rlen > max_size) 238 rlen = max_size; 239 SSHBUF_DBG(("new alloc = %zu", rlen)); 240 if ((dp = recallocarray(buf->d, buf->alloc, rlen, 1)) == NULL) 241 return SSH_ERR_ALLOC_FAIL; 242 buf->cd = buf->d = dp; 243 buf->alloc = rlen; 244 } 245 SSHBUF_TELL("new-max"); 246 if (max_size < buf->alloc) 247 return SSH_ERR_NO_BUFFER_SPACE; 248 buf->max_size = max_size; 249 return 0; 250 } 251 252 size_t 253 sshbuf_len(const struct sshbuf *buf) 254 { 255 if (sshbuf_check_sanity(buf) != 0) 256 return 0; 257 return buf->size - buf->off; 258 } 259 260 size_t 261 sshbuf_avail(const struct sshbuf *buf) 262 { 263 if (sshbuf_check_sanity(buf) != 0 || buf->readonly || buf->refcount > 1) 264 return 0; 265 return buf->max_size - (buf->size - buf->off); 266 } 267 268 const u_char * 269 sshbuf_ptr(const struct sshbuf *buf) 270 { 271 if (sshbuf_check_sanity(buf) != 0) 272 return NULL; 273 return buf->cd + buf->off; 274 } 275 276 u_char * 277 sshbuf_mutable_ptr(const struct sshbuf *buf) 278 { 279 if (sshbuf_check_sanity(buf) != 0 || buf->readonly || buf->refcount > 1) 280 return NULL; 281 return buf->d + buf->off; 282 } 283 284 int 285 sshbuf_check_reserve(const struct sshbuf *buf, size_t len) 286 { 287 int r; 288 289 if ((r = sshbuf_check_sanity(buf)) != 0) 290 return r; 291 if (buf->readonly || buf->refcount > 1) 292 return SSH_ERR_BUFFER_READ_ONLY; 293 SSHBUF_TELL("check"); 294 /* Check that len is reasonable and that max_size + available < len */ 295 if (len > buf->max_size || buf->max_size - len < buf->size - buf->off) 296 return SSH_ERR_NO_BUFFER_SPACE; 297 return 0; 298 } 299 300 int 301 sshbuf_allocate(struct sshbuf *buf, size_t len) 302 { 303 size_t rlen, need; 304 u_char *dp; 305 int r; 306 307 SSHBUF_DBG(("allocate buf = %p len = %zu", buf, len)); 308 if ((r = sshbuf_check_reserve(buf, len)) != 0) 309 return r; 310 /* 311 * If the requested allocation appended would push us past max_size 312 * then pack the buffer, zeroing buf->off. 313 */ 314 sshbuf_maybe_pack(buf, buf->size + len > buf->max_size); 315 SSHBUF_TELL("allocate"); 316 if (len + buf->size <= buf->alloc) 317 return 0; /* already have it. */ 318 319 /* 320 * Prefer to alloc in SSHBUF_SIZE_INC units, but 321 * allocate less if doing so would overflow max_size. 322 */ 323 need = len + buf->size - buf->alloc; 324 rlen = ROUNDUP(buf->alloc + need, SSHBUF_SIZE_INC); 325 SSHBUF_DBG(("need %zu initial rlen %zu", need, rlen)); 326 if (rlen > buf->max_size) 327 rlen = buf->alloc + need; 328 SSHBUF_DBG(("adjusted rlen %zu", rlen)); 329 if ((dp = recallocarray(buf->d, buf->alloc, rlen, 1)) == NULL) { 330 SSHBUF_DBG(("realloc fail")); 331 return SSH_ERR_ALLOC_FAIL; 332 } 333 buf->alloc = rlen; 334 buf->cd = buf->d = dp; 335 if ((r = sshbuf_check_reserve(buf, len)) < 0) { 336 /* shouldn't fail */ 337 return r; 338 } 339 SSHBUF_TELL("done"); 340 return 0; 341 } 342 343 int 344 sshbuf_reserve(struct sshbuf *buf, size_t len, u_char **dpp) 345 { 346 u_char *dp; 347 int r; 348 349 if (dpp != NULL) 350 *dpp = NULL; 351 352 SSHBUF_DBG(("reserve buf = %p len = %zu", buf, len)); 353 if ((r = sshbuf_allocate(buf, len)) != 0) 354 return r; 355 356 dp = buf->d + buf->size; 357 buf->size += len; 358 if (dpp != NULL) 359 *dpp = dp; 360 return 0; 361 } 362 363 int 364 sshbuf_consume(struct sshbuf *buf, size_t len) 365 { 366 int r; 367 368 SSHBUF_DBG(("len = %zu", len)); 369 if ((r = sshbuf_check_sanity(buf)) != 0) 370 return r; 371 if (len == 0) 372 return 0; 373 if (len > sshbuf_len(buf)) 374 return SSH_ERR_MESSAGE_INCOMPLETE; 375 buf->off += len; 376 /* deal with empty buffer */ 377 if (buf->off == buf->size) 378 buf->off = buf->size = 0; 379 SSHBUF_TELL("done"); 380 return 0; 381 } 382 383 int 384 sshbuf_consume_end(struct sshbuf *buf, size_t len) 385 { 386 int r; 387 388 SSHBUF_DBG(("len = %zu", len)); 389 if ((r = sshbuf_check_sanity(buf)) != 0) 390 return r; 391 if (len == 0) 392 return 0; 393 if (len > sshbuf_len(buf)) 394 return SSH_ERR_MESSAGE_INCOMPLETE; 395 buf->size -= len; 396 SSHBUF_TELL("done"); 397 return 0; 398 } 399 400