1 /*	$OpenBSD: sshbuf-getput-basic.c,v 1.11 2020/06/05 03:25:35 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 
23 #include <stdarg.h>
24 #include <stdlib.h>
25 #include <stdio.h>
26 #include <string.h>
27 #ifdef HAVE_STDINT_H
28 # include <stdint.h>
29 #endif
30 
31 #include "ssherr.h"
32 #include "sshbuf.h"
33 
34 int
sshbuf_get(struct sshbuf * buf,void * v,size_t len)35 sshbuf_get(struct sshbuf *buf, void *v, size_t len)
36 {
37 	const u_char *p = sshbuf_ptr(buf);
38 	int r;
39 
40 	if ((r = sshbuf_consume(buf, len)) < 0)
41 		return r;
42 	if (v != NULL && len != 0)
43 		memcpy(v, p, len);
44 	return 0;
45 }
46 
47 int
sshbuf_get_u64(struct sshbuf * buf,u_int64_t * valp)48 sshbuf_get_u64(struct sshbuf *buf, u_int64_t *valp)
49 {
50 	const u_char *p = sshbuf_ptr(buf);
51 	int r;
52 
53 	if ((r = sshbuf_consume(buf, 8)) < 0)
54 		return r;
55 	if (valp != NULL)
56 		*valp = PEEK_U64(p);
57 	return 0;
58 }
59 
60 int
sshbuf_get_u32(struct sshbuf * buf,u_int32_t * valp)61 sshbuf_get_u32(struct sshbuf *buf, u_int32_t *valp)
62 {
63 	const u_char *p = sshbuf_ptr(buf);
64 	int r;
65 
66 	if ((r = sshbuf_consume(buf, 4)) < 0)
67 		return r;
68 	if (valp != NULL)
69 		*valp = PEEK_U32(p);
70 	return 0;
71 }
72 
73 int
sshbuf_get_u16(struct sshbuf * buf,u_int16_t * valp)74 sshbuf_get_u16(struct sshbuf *buf, u_int16_t *valp)
75 {
76 	const u_char *p = sshbuf_ptr(buf);
77 	int r;
78 
79 	if ((r = sshbuf_consume(buf, 2)) < 0)
80 		return r;
81 	if (valp != NULL)
82 		*valp = PEEK_U16(p);
83 	return 0;
84 }
85 
86 int
sshbuf_get_u8(struct sshbuf * buf,u_char * valp)87 sshbuf_get_u8(struct sshbuf *buf, u_char *valp)
88 {
89 	const u_char *p = sshbuf_ptr(buf);
90 	int r;
91 
92 	if ((r = sshbuf_consume(buf, 1)) < 0)
93 		return r;
94 	if (valp != NULL)
95 		*valp = (u_int8_t)*p;
96 	return 0;
97 }
98 
99 static int
check_offset(const struct sshbuf * buf,int wr,size_t offset,size_t len)100 check_offset(const struct sshbuf *buf, int wr, size_t offset, size_t len)
101 {
102 	if (sshbuf_ptr(buf) == NULL) /* calls sshbuf_check_sanity() */
103 		return SSH_ERR_INTERNAL_ERROR;
104 	if (offset >= SIZE_MAX - len)
105 		return SSH_ERR_INVALID_ARGUMENT;
106 	if (offset + len > sshbuf_len(buf)) {
107 		return wr ?
108 		    SSH_ERR_NO_BUFFER_SPACE : SSH_ERR_MESSAGE_INCOMPLETE;
109 	}
110 	return 0;
111 }
112 
113 static int
check_roffset(const struct sshbuf * buf,size_t offset,size_t len,const u_char ** p)114 check_roffset(const struct sshbuf *buf, size_t offset, size_t len,
115     const u_char **p)
116 {
117 	int r;
118 
119 	*p = NULL;
120 	if ((r = check_offset(buf, 0, offset, len)) != 0)
121 		return r;
122 	*p = sshbuf_ptr(buf) + offset;
123 	return 0;
124 }
125 
126 int
sshbuf_peek_u64(const struct sshbuf * buf,size_t offset,u_int64_t * valp)127 sshbuf_peek_u64(const struct sshbuf *buf, size_t offset, u_int64_t *valp)
128 {
129 	const u_char *p = NULL;
130 	int r;
131 
132 	if (valp != NULL)
133 		*valp = 0;
134 	if ((r = check_roffset(buf, offset, 8, &p)) != 0)
135 		return r;
136 	if (valp != NULL)
137 		*valp = PEEK_U64(p);
138 	return 0;
139 }
140 
141 int
sshbuf_peek_u32(const struct sshbuf * buf,size_t offset,u_int32_t * valp)142 sshbuf_peek_u32(const struct sshbuf *buf, size_t offset, u_int32_t *valp)
143 {
144 	const u_char *p = NULL;
145 	int r;
146 
147 	if (valp != NULL)
148 		*valp = 0;
149 	if ((r = check_roffset(buf, offset, 4, &p)) != 0)
150 		return r;
151 	if (valp != NULL)
152 		*valp = PEEK_U32(p);
153 	return 0;
154 }
155 
156 int
sshbuf_peek_u16(const struct sshbuf * buf,size_t offset,u_int16_t * valp)157 sshbuf_peek_u16(const struct sshbuf *buf, size_t offset, u_int16_t *valp)
158 {
159 	const u_char *p = NULL;
160 	int r;
161 
162 	if (valp != NULL)
163 		*valp = 0;
164 	if ((r = check_roffset(buf, offset, 2, &p)) != 0)
165 		return r;
166 	if (valp != NULL)
167 		*valp = PEEK_U16(p);
168 	return 0;
169 }
170 
171 int
sshbuf_peek_u8(const struct sshbuf * buf,size_t offset,u_char * valp)172 sshbuf_peek_u8(const struct sshbuf *buf, size_t offset, u_char *valp)
173 {
174 	const u_char *p = NULL;
175 	int r;
176 
177 	if (valp != NULL)
178 		*valp = 0;
179 	if ((r = check_roffset(buf, offset, 1, &p)) != 0)
180 		return r;
181 	if (valp != NULL)
182 		*valp = *p;
183 	return 0;
184 }
185 
186 int
sshbuf_get_string(struct sshbuf * buf,u_char ** valp,size_t * lenp)187 sshbuf_get_string(struct sshbuf *buf, u_char **valp, size_t *lenp)
188 {
189 	const u_char *val;
190 	size_t len;
191 	int r;
192 
193 	if (valp != NULL)
194 		*valp = NULL;
195 	if (lenp != NULL)
196 		*lenp = 0;
197 	if ((r = sshbuf_get_string_direct(buf, &val, &len)) < 0)
198 		return r;
199 	if (valp != NULL) {
200 		if ((*valp = malloc(len + 1)) == NULL) {
201 			SSHBUF_DBG(("SSH_ERR_ALLOC_FAIL"));
202 			return SSH_ERR_ALLOC_FAIL;
203 		}
204 		if (len != 0)
205 			memcpy(*valp, val, len);
206 		(*valp)[len] = '\0';
207 	}
208 	if (lenp != NULL)
209 		*lenp = len;
210 	return 0;
211 }
212 
213 int
sshbuf_get_string_direct(struct sshbuf * buf,const u_char ** valp,size_t * lenp)214 sshbuf_get_string_direct(struct sshbuf *buf, const u_char **valp, size_t *lenp)
215 {
216 	size_t len;
217 	const u_char *p;
218 	int r;
219 
220 	if (valp != NULL)
221 		*valp = NULL;
222 	if (lenp != NULL)
223 		*lenp = 0;
224 	if ((r = sshbuf_peek_string_direct(buf, &p, &len)) < 0)
225 		return r;
226 	if (valp != NULL)
227 		*valp = p;
228 	if (lenp != NULL)
229 		*lenp = len;
230 	if (sshbuf_consume(buf, len + 4) != 0) {
231 		/* Shouldn't happen */
232 		SSHBUF_DBG(("SSH_ERR_INTERNAL_ERROR"));
233 		SSHBUF_ABORT();
234 		return SSH_ERR_INTERNAL_ERROR;
235 	}
236 	return 0;
237 }
238 
239 int
sshbuf_peek_string_direct(const struct sshbuf * buf,const u_char ** valp,size_t * lenp)240 sshbuf_peek_string_direct(const struct sshbuf *buf, const u_char **valp,
241     size_t *lenp)
242 {
243 	u_int32_t len;
244 	const u_char *p = sshbuf_ptr(buf);
245 
246 	if (valp != NULL)
247 		*valp = NULL;
248 	if (lenp != NULL)
249 		*lenp = 0;
250 	if (sshbuf_len(buf) < 4) {
251 		SSHBUF_DBG(("SSH_ERR_MESSAGE_INCOMPLETE"));
252 		return SSH_ERR_MESSAGE_INCOMPLETE;
253 	}
254 	len = PEEK_U32(p);
255 	if (len > SSHBUF_SIZE_MAX - 4) {
256 		SSHBUF_DBG(("SSH_ERR_STRING_TOO_LARGE"));
257 		return SSH_ERR_STRING_TOO_LARGE;
258 	}
259 	if (sshbuf_len(buf) - 4 < len) {
260 		SSHBUF_DBG(("SSH_ERR_MESSAGE_INCOMPLETE"));
261 		return SSH_ERR_MESSAGE_INCOMPLETE;
262 	}
263 	if (valp != NULL)
264 		*valp = p + 4;
265 	if (lenp != NULL)
266 		*lenp = len;
267 	return 0;
268 }
269 
270 int
sshbuf_get_cstring(struct sshbuf * buf,char ** valp,size_t * lenp)271 sshbuf_get_cstring(struct sshbuf *buf, char **valp, size_t *lenp)
272 {
273 	size_t len;
274 	const u_char *p, *z;
275 	int r;
276 
277 	if (valp != NULL)
278 		*valp = NULL;
279 	if (lenp != NULL)
280 		*lenp = 0;
281 	if ((r = sshbuf_peek_string_direct(buf, &p, &len)) != 0)
282 		return r;
283 	/* Allow a \0 only at the end of the string */
284 	if (len > 0 &&
285 	    (z = memchr(p , '\0', len)) != NULL && z < p + len - 1) {
286 		SSHBUF_DBG(("SSH_ERR_INVALID_FORMAT"));
287 		return SSH_ERR_INVALID_FORMAT;
288 	}
289 	if ((r = sshbuf_skip_string(buf)) != 0)
290 		return -1;
291 	if (valp != NULL) {
292 		if ((*valp = malloc(len + 1)) == NULL) {
293 			SSHBUF_DBG(("SSH_ERR_ALLOC_FAIL"));
294 			return SSH_ERR_ALLOC_FAIL;
295 		}
296 		if (len != 0)
297 			memcpy(*valp, p, len);
298 		(*valp)[len] = '\0';
299 	}
300 	if (lenp != NULL)
301 		*lenp = (size_t)len;
302 	return 0;
303 }
304 
305 int
sshbuf_get_stringb(struct sshbuf * buf,struct sshbuf * v)306 sshbuf_get_stringb(struct sshbuf *buf, struct sshbuf *v)
307 {
308 	u_int32_t len;
309 	u_char *p;
310 	int r;
311 
312 	/*
313 	 * Use sshbuf_peek_string_direct() to figure out if there is
314 	 * a complete string in 'buf' and copy the string directly
315 	 * into 'v'.
316 	 */
317 	if ((r = sshbuf_peek_string_direct(buf, NULL, NULL)) != 0 ||
318 	    (r = sshbuf_get_u32(buf, &len)) != 0 ||
319 	    (r = sshbuf_reserve(v, len, &p)) != 0 ||
320 	    (r = sshbuf_get(buf, p, len)) != 0)
321 		return r;
322 	return 0;
323 }
324 
325 int
sshbuf_put(struct sshbuf * buf,const void * v,size_t len)326 sshbuf_put(struct sshbuf *buf, const void *v, size_t len)
327 {
328 	u_char *p;
329 	int r;
330 
331 	if ((r = sshbuf_reserve(buf, len, &p)) < 0)
332 		return r;
333 	if (len != 0)
334 		memcpy(p, v, len);
335 	return 0;
336 }
337 
338 int
sshbuf_putb(struct sshbuf * buf,const struct sshbuf * v)339 sshbuf_putb(struct sshbuf *buf, const struct sshbuf *v)
340 {
341 	if (v == NULL)
342 		return 0;
343 	return sshbuf_put(buf, sshbuf_ptr(v), sshbuf_len(v));
344 }
345 
346 int
sshbuf_putf(struct sshbuf * buf,const char * fmt,...)347 sshbuf_putf(struct sshbuf *buf, const char *fmt, ...)
348 {
349 	va_list ap;
350 	int r;
351 
352 	va_start(ap, fmt);
353 	r = sshbuf_putfv(buf, fmt, ap);
354 	va_end(ap);
355 	return r;
356 }
357 
358 int
sshbuf_putfv(struct sshbuf * buf,const char * fmt,va_list ap)359 sshbuf_putfv(struct sshbuf *buf, const char *fmt, va_list ap)
360 {
361 	va_list ap2;
362 	int r, len;
363 	u_char *p;
364 
365 	VA_COPY(ap2, ap);
366 	if ((len = vsnprintf(NULL, 0, fmt, ap2)) < 0) {
367 		r = SSH_ERR_INVALID_ARGUMENT;
368 		goto out;
369 	}
370 	if (len == 0) {
371 		r = 0;
372 		goto out; /* Nothing to do */
373 	}
374 	va_end(ap2);
375 	VA_COPY(ap2, ap);
376 	if ((r = sshbuf_reserve(buf, (size_t)len + 1, &p)) < 0)
377 		goto out;
378 	if ((r = vsnprintf((char *)p, len + 1, fmt, ap2)) != len) {
379 		r = SSH_ERR_INTERNAL_ERROR;
380 		goto out; /* Shouldn't happen */
381 	}
382 	/* Consume terminating \0 */
383 	if ((r = sshbuf_consume_end(buf, 1)) != 0)
384 		goto out;
385 	r = 0;
386  out:
387 	va_end(ap2);
388 	return r;
389 }
390 
391 int
sshbuf_put_u64(struct sshbuf * buf,u_int64_t val)392 sshbuf_put_u64(struct sshbuf *buf, u_int64_t val)
393 {
394 	u_char *p;
395 	int r;
396 
397 	if ((r = sshbuf_reserve(buf, 8, &p)) < 0)
398 		return r;
399 	POKE_U64(p, val);
400 	return 0;
401 }
402 
403 int
sshbuf_put_u32(struct sshbuf * buf,u_int32_t val)404 sshbuf_put_u32(struct sshbuf *buf, u_int32_t val)
405 {
406 	u_char *p;
407 	int r;
408 
409 	if ((r = sshbuf_reserve(buf, 4, &p)) < 0)
410 		return r;
411 	POKE_U32(p, val);
412 	return 0;
413 }
414 
415 int
sshbuf_put_u16(struct sshbuf * buf,u_int16_t val)416 sshbuf_put_u16(struct sshbuf *buf, u_int16_t val)
417 {
418 	u_char *p;
419 	int r;
420 
421 	if ((r = sshbuf_reserve(buf, 2, &p)) < 0)
422 		return r;
423 	POKE_U16(p, val);
424 	return 0;
425 }
426 
427 int
sshbuf_put_u8(struct sshbuf * buf,u_char val)428 sshbuf_put_u8(struct sshbuf *buf, u_char val)
429 {
430 	u_char *p;
431 	int r;
432 
433 	if ((r = sshbuf_reserve(buf, 1, &p)) < 0)
434 		return r;
435 	p[0] = val;
436 	return 0;
437 }
438 
439 static int
check_woffset(struct sshbuf * buf,size_t offset,size_t len,u_char ** p)440 check_woffset(struct sshbuf *buf, size_t offset, size_t len, u_char **p)
441 {
442 	int r;
443 
444 	*p = NULL;
445 	if ((r = check_offset(buf, 1, offset, len)) != 0)
446 		return r;
447 	if (sshbuf_mutable_ptr(buf) == NULL)
448 		return SSH_ERR_BUFFER_READ_ONLY;
449 	*p = sshbuf_mutable_ptr(buf) + offset;
450 	return 0;
451 }
452 
453 int
sshbuf_poke_u64(struct sshbuf * buf,size_t offset,u_int64_t val)454 sshbuf_poke_u64(struct sshbuf *buf, size_t offset, u_int64_t val)
455 {
456 	u_char *p = NULL;
457 	int r;
458 
459 	if ((r = check_woffset(buf, offset, 8, &p)) != 0)
460 		return r;
461 	POKE_U64(p, val);
462 	return 0;
463 }
464 
465 int
sshbuf_poke_u32(struct sshbuf * buf,size_t offset,u_int32_t val)466 sshbuf_poke_u32(struct sshbuf *buf, size_t offset, u_int32_t val)
467 {
468 	u_char *p = NULL;
469 	int r;
470 
471 	if ((r = check_woffset(buf, offset, 4, &p)) != 0)
472 		return r;
473 	POKE_U32(p, val);
474 	return 0;
475 }
476 
477 int
sshbuf_poke_u16(struct sshbuf * buf,size_t offset,u_int16_t val)478 sshbuf_poke_u16(struct sshbuf *buf, size_t offset, u_int16_t val)
479 {
480 	u_char *p = NULL;
481 	int r;
482 
483 	if ((r = check_woffset(buf, offset, 2, &p)) != 0)
484 		return r;
485 	POKE_U16(p, val);
486 	return 0;
487 }
488 
489 int
sshbuf_poke_u8(struct sshbuf * buf,size_t offset,u_char val)490 sshbuf_poke_u8(struct sshbuf *buf, size_t offset, u_char val)
491 {
492 	u_char *p = NULL;
493 	int r;
494 
495 	if ((r = check_woffset(buf, offset, 1, &p)) != 0)
496 		return r;
497 	*p = val;
498 	return 0;
499 }
500 
501 int
sshbuf_poke(struct sshbuf * buf,size_t offset,void * v,size_t len)502 sshbuf_poke(struct sshbuf *buf, size_t offset, void *v, size_t len)
503 {
504 	u_char *p = NULL;
505 	int r;
506 
507 	if ((r = check_woffset(buf, offset, len, &p)) != 0)
508 		return r;
509 	memcpy(p, v, len);
510 	return 0;
511 }
512 
513 int
sshbuf_put_string(struct sshbuf * buf,const void * v,size_t len)514 sshbuf_put_string(struct sshbuf *buf, const void *v, size_t len)
515 {
516 	u_char *d;
517 	int r;
518 
519 	if (len > SSHBUF_SIZE_MAX - 4) {
520 		SSHBUF_DBG(("SSH_ERR_NO_BUFFER_SPACE"));
521 		return SSH_ERR_NO_BUFFER_SPACE;
522 	}
523 	if ((r = sshbuf_reserve(buf, len + 4, &d)) < 0)
524 		return r;
525 	POKE_U32(d, len);
526 	if (len != 0)
527 		memcpy(d + 4, v, len);
528 	return 0;
529 }
530 
531 int
sshbuf_put_cstring(struct sshbuf * buf,const char * v)532 sshbuf_put_cstring(struct sshbuf *buf, const char *v)
533 {
534 	return sshbuf_put_string(buf, v, v == NULL ? 0 : strlen(v));
535 }
536 
537 int
sshbuf_put_stringb(struct sshbuf * buf,const struct sshbuf * v)538 sshbuf_put_stringb(struct sshbuf *buf, const struct sshbuf *v)
539 {
540 	if (v == NULL)
541 		return sshbuf_put_string(buf, NULL, 0);
542 
543 	return sshbuf_put_string(buf, sshbuf_ptr(v), sshbuf_len(v));
544 }
545 
546 int
sshbuf_froms(struct sshbuf * buf,struct sshbuf ** bufp)547 sshbuf_froms(struct sshbuf *buf, struct sshbuf **bufp)
548 {
549 	const u_char *p;
550 	size_t len;
551 	struct sshbuf *ret;
552 	int r;
553 
554 	if (buf == NULL || bufp == NULL)
555 		return SSH_ERR_INVALID_ARGUMENT;
556 	*bufp = NULL;
557 	if ((r = sshbuf_peek_string_direct(buf, &p, &len)) != 0)
558 		return r;
559 	if ((ret = sshbuf_from(p, len)) == NULL)
560 		return SSH_ERR_ALLOC_FAIL;
561 	if ((r = sshbuf_consume(buf, len + 4)) != 0 ||  /* Shouldn't happen */
562 	    (r = sshbuf_set_parent(ret, buf)) != 0) {
563 		sshbuf_free(ret);
564 		return r;
565 	}
566 	*bufp = ret;
567 	return 0;
568 }
569 
570 int
sshbuf_put_bignum2_bytes(struct sshbuf * buf,const void * v,size_t len)571 sshbuf_put_bignum2_bytes(struct sshbuf *buf, const void *v, size_t len)
572 {
573 	u_char *d;
574 	const u_char *s = (const u_char *)v;
575 	int r, prepend;
576 
577 	if (len > SSHBUF_SIZE_MAX - 5) {
578 		SSHBUF_DBG(("SSH_ERR_NO_BUFFER_SPACE"));
579 		return SSH_ERR_NO_BUFFER_SPACE;
580 	}
581 	/* Skip leading zero bytes */
582 	for (; len > 0 && *s == 0; len--, s++)
583 		;
584 	/*
585 	 * If most significant bit is set then prepend a zero byte to
586 	 * avoid interpretation as a negative number.
587 	 */
588 	prepend = len > 0 && (s[0] & 0x80) != 0;
589 	if ((r = sshbuf_reserve(buf, len + 4 + prepend, &d)) < 0)
590 		return r;
591 	POKE_U32(d, len + prepend);
592 	if (prepend)
593 		d[4] = 0;
594 	if (len != 0)
595 		memcpy(d + 4 + prepend, s, len);
596 	return 0;
597 }
598 
599 int
sshbuf_get_bignum2_bytes_direct(struct sshbuf * buf,const u_char ** valp,size_t * lenp)600 sshbuf_get_bignum2_bytes_direct(struct sshbuf *buf,
601     const u_char **valp, size_t *lenp)
602 {
603 	const u_char *d;
604 	size_t len, olen;
605 	int r;
606 
607 	if ((r = sshbuf_peek_string_direct(buf, &d, &olen)) < 0)
608 		return r;
609 	len = olen;
610 	/* Refuse negative (MSB set) bignums */
611 	if ((len != 0 && (*d & 0x80) != 0))
612 		return SSH_ERR_BIGNUM_IS_NEGATIVE;
613 	/* Refuse overlong bignums, allow prepended \0 to avoid MSB set */
614 	if (len > SSHBUF_MAX_BIGNUM + 1 ||
615 	    (len == SSHBUF_MAX_BIGNUM + 1 && *d != 0))
616 		return SSH_ERR_BIGNUM_TOO_LARGE;
617 	/* Trim leading zeros */
618 	while (len > 0 && *d == 0x00) {
619 		d++;
620 		len--;
621 	}
622 	if (valp != NULL)
623 		*valp = d;
624 	if (lenp != NULL)
625 		*lenp = len;
626 	if (sshbuf_consume(buf, olen + 4) != 0) {
627 		/* Shouldn't happen */
628 		SSHBUF_DBG(("SSH_ERR_INTERNAL_ERROR"));
629 		SSHBUF_ABORT();
630 		return SSH_ERR_INTERNAL_ERROR;
631 	}
632 	return 0;
633 }
634