sshbuf-getput-basic.c revision 1.10 
1/*	$OpenBSD: sshbuf-getput-basic.c,v 1.10 2019/12/13 19:09:37 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#include <sys/types.h>
19
20#include <stdarg.h>
21#include <stdlib.h>
22#include <stdio.h>
23#include <string.h>
24#include <stdint.h>
25
26#include "ssherr.h"
27#define SSHBUF_INTERNAL
28#include "sshbuf.h"
29
30int
31sshbuf_get(struct sshbuf *buf, void *v, size_t len)
32{
33	const u_char *p = sshbuf_ptr(buf);
34	int r;
35
36	if ((r = sshbuf_consume(buf, len)) < 0)
37		return r;
38	if (v != NULL && len != 0)
39		memcpy(v, p, len);
40	return 0;
41}
42
43int
44sshbuf_get_u64(struct sshbuf *buf, u_int64_t *valp)
45{
46	const u_char *p = sshbuf_ptr(buf);
47	int r;
48
49	if ((r = sshbuf_consume(buf, 8)) < 0)
50		return r;
51	if (valp != NULL)
52		*valp = PEEK_U64(p);
53	return 0;
54}
55
56int
57sshbuf_get_u32(struct sshbuf *buf, u_int32_t *valp)
58{
59	const u_char *p = sshbuf_ptr(buf);
60	int r;
61
62	if ((r = sshbuf_consume(buf, 4)) < 0)
63		return r;
64	if (valp != NULL)
65		*valp = PEEK_U32(p);
66	return 0;
67}
68
69int
70sshbuf_get_u16(struct sshbuf *buf, u_int16_t *valp)
71{
72	const u_char *p = sshbuf_ptr(buf);
73	int r;
74
75	if ((r = sshbuf_consume(buf, 2)) < 0)
76		return r;
77	if (valp != NULL)
78		*valp = PEEK_U16(p);
79	return 0;
80}
81
82int
83sshbuf_get_u8(struct sshbuf *buf, u_char *valp)
84{
85	const u_char *p = sshbuf_ptr(buf);
86	int r;
87
88	if ((r = sshbuf_consume(buf, 1)) < 0)
89		return r;
90	if (valp != NULL)
91		*valp = (u_int8_t)*p;
92	return 0;
93}
94
95static int
96check_offset(const struct sshbuf *buf, int wr, size_t offset, size_t len)
97{
98	if (sshbuf_ptr(buf) == NULL) /* calls sshbuf_check_sanity() */
99		return SSH_ERR_INTERNAL_ERROR;
100	if (offset >= SIZE_MAX - len)
101		return SSH_ERR_INVALID_ARGUMENT;
102	if (offset + len > sshbuf_len(buf)) {
103		return wr ?
104		    SSH_ERR_NO_BUFFER_SPACE : SSH_ERR_MESSAGE_INCOMPLETE;
105	}
106	return 0;
107}
108
109static int
110check_roffset(const struct sshbuf *buf, size_t offset, size_t len,
111    const u_char **p)
112{
113	int r;
114
115	*p = NULL;
116	if ((r = check_offset(buf, 0, offset, len)) != 0)
117		return r;
118	*p = sshbuf_ptr(buf) + offset;
119	return 0;
120}
121
122int
123sshbuf_peek_u64(const struct sshbuf *buf, size_t offset, u_int64_t *valp)
124{
125	const u_char *p = NULL;
126	int r;
127
128	if (valp != NULL)
129		*valp = 0;
130	if ((r = check_roffset(buf, offset, 8, &p)) != 0)
131		return r;
132	if (valp != NULL)
133		*valp = PEEK_U64(p);
134	return 0;
135}
136
137int
138sshbuf_peek_u32(const struct sshbuf *buf, size_t offset, u_int32_t *valp)
139{
140	const u_char *p = NULL;
141	int r;
142
143	if (valp != NULL)
144		*valp = 0;
145	if ((r = check_roffset(buf, offset, 4, &p)) != 0)
146		return r;
147	if (valp != NULL)
148		*valp = PEEK_U32(p);
149	return 0;
150}
151
152int
153sshbuf_peek_u16(const struct sshbuf *buf, size_t offset, u_int16_t *valp)
154{
155	const u_char *p = NULL;
156	int r;
157
158	if (valp != NULL)
159		*valp = 0;
160	if ((r = check_roffset(buf, offset, 2, &p)) != 0)
161		return r;
162	if (valp != NULL)
163		*valp = PEEK_U16(p);
164	return 0;
165}
166
167int
168sshbuf_peek_u8(const struct sshbuf *buf, size_t offset, u_char *valp)
169{
170	const u_char *p = NULL;
171	int r;
172
173	if (valp != NULL)
174		*valp = 0;
175	if ((r = check_roffset(buf, offset, 1, &p)) != 0)
176		return r;
177	if (valp != NULL)
178		*valp = *p;
179	return 0;
180}
181
182int
183sshbuf_get_string(struct sshbuf *buf, u_char **valp, size_t *lenp)
184{
185	const u_char *val;
186	size_t len;
187	int r;
188
189	if (valp != NULL)
190		*valp = NULL;
191	if (lenp != NULL)
192		*lenp = 0;
193	if ((r = sshbuf_get_string_direct(buf, &val, &len)) < 0)
194		return r;
195	if (valp != NULL) {
196		if ((*valp = malloc(len + 1)) == NULL) {
197			SSHBUF_DBG(("SSH_ERR_ALLOC_FAIL"));
198			return SSH_ERR_ALLOC_FAIL;
199		}
200		if (len != 0)
201			memcpy(*valp, val, len);
202		(*valp)[len] = '\0';
203	}
204	if (lenp != NULL)
205		*lenp = len;
206	return 0;
207}
208
209int
210sshbuf_get_string_direct(struct sshbuf *buf, const u_char **valp, size_t *lenp)
211{
212	size_t len;
213	const u_char *p;
214	int r;
215
216	if (valp != NULL)
217		*valp = NULL;
218	if (lenp != NULL)
219		*lenp = 0;
220	if ((r = sshbuf_peek_string_direct(buf, &p, &len)) < 0)
221		return r;
222	if (valp != NULL)
223		*valp = p;
224	if (lenp != NULL)
225		*lenp = len;
226	if (sshbuf_consume(buf, len + 4) != 0) {
227		/* Shouldn't happen */
228		SSHBUF_DBG(("SSH_ERR_INTERNAL_ERROR"));
229		SSHBUF_ABORT();
230		return SSH_ERR_INTERNAL_ERROR;
231	}
232	return 0;
233}
234
235int
236sshbuf_peek_string_direct(const struct sshbuf *buf, const u_char **valp,
237    size_t *lenp)
238{
239	u_int32_t len;
240	const u_char *p = sshbuf_ptr(buf);
241
242	if (valp != NULL)
243		*valp = NULL;
244	if (lenp != NULL)
245		*lenp = 0;
246	if (sshbuf_len(buf) < 4) {
247		SSHBUF_DBG(("SSH_ERR_MESSAGE_INCOMPLETE"));
248		return SSH_ERR_MESSAGE_INCOMPLETE;
249	}
250	len = PEEK_U32(p);
251	if (len > SSHBUF_SIZE_MAX - 4) {
252		SSHBUF_DBG(("SSH_ERR_STRING_TOO_LARGE"));
253		return SSH_ERR_STRING_TOO_LARGE;
254	}
255	if (sshbuf_len(buf) - 4 < len) {
256		SSHBUF_DBG(("SSH_ERR_MESSAGE_INCOMPLETE"));
257		return SSH_ERR_MESSAGE_INCOMPLETE;
258	}
259	if (valp != NULL)
260		*valp = p + 4;
261	if (lenp != NULL)
262		*lenp = len;
263	return 0;
264}
265
266int
267sshbuf_get_cstring(struct sshbuf *buf, char **valp, size_t *lenp)
268{
269	size_t len;
270	const u_char *p, *z;
271	int r;
272
273	if (valp != NULL)
274		*valp = NULL;
275	if (lenp != NULL)
276		*lenp = 0;
277	if ((r = sshbuf_peek_string_direct(buf, &p, &len)) != 0)
278		return r;
279	/* Allow a \0 only at the end of the string */
280	if (len > 0 &&
281	    (z = memchr(p , '\0', len)) != NULL && z < p + len - 1) {
282		SSHBUF_DBG(("SSH_ERR_INVALID_FORMAT"));
283		return SSH_ERR_INVALID_FORMAT;
284	}
285	if ((r = sshbuf_skip_string(buf)) != 0)
286		return -1;
287	if (valp != NULL) {
288		if ((*valp = malloc(len + 1)) == NULL) {
289			SSHBUF_DBG(("SSH_ERR_ALLOC_FAIL"));
290			return SSH_ERR_ALLOC_FAIL;
291		}
292		if (len != 0)
293			memcpy(*valp, p, len);
294		(*valp)[len] = '\0';
295	}
296	if (lenp != NULL)
297		*lenp = (size_t)len;
298	return 0;
299}
300
301int
302sshbuf_get_stringb(struct sshbuf *buf, struct sshbuf *v)
303{
304	u_int32_t len;
305	u_char *p;
306	int r;
307
308	/*
309	 * Use sshbuf_peek_string_direct() to figure out if there is
310	 * a complete string in 'buf' and copy the string directly
311	 * into 'v'.
312	 */
313	if ((r = sshbuf_peek_string_direct(buf, NULL, NULL)) != 0 ||
314	    (r = sshbuf_get_u32(buf, &len)) != 0 ||
315	    (r = sshbuf_reserve(v, len, &p)) != 0 ||
316	    (r = sshbuf_get(buf, p, len)) != 0)
317		return r;
318	return 0;
319}
320
321int
322sshbuf_put(struct sshbuf *buf, const void *v, size_t len)
323{
324	u_char *p;
325	int r;
326
327	if ((r = sshbuf_reserve(buf, len, &p)) < 0)
328		return r;
329	if (len != 0)
330		memcpy(p, v, len);
331	return 0;
332}
333
334int
335sshbuf_putb(struct sshbuf *buf, const struct sshbuf *v)
336{
337	return sshbuf_put(buf, sshbuf_ptr(v), sshbuf_len(v));
338}
339
340int
341sshbuf_putf(struct sshbuf *buf, const char *fmt, ...)
342{
343	va_list ap;
344	int r;
345
346	va_start(ap, fmt);
347	r = sshbuf_putfv(buf, fmt, ap);
348	va_end(ap);
349	return r;
350}
351
352int
353sshbuf_putfv(struct sshbuf *buf, const char *fmt, va_list ap)
354{
355	va_list ap2;
356	int r, len;
357	u_char *p;
358
359	va_copy(ap2, ap);
360	if ((len = vsnprintf(NULL, 0, fmt, ap2)) < 0) {
361		r = SSH_ERR_INVALID_ARGUMENT;
362		goto out;
363	}
364	if (len == 0) {
365		r = 0;
366		goto out; /* Nothing to do */
367	}
368	va_end(ap2);
369	va_copy(ap2, ap);
370	if ((r = sshbuf_reserve(buf, (size_t)len + 1, &p)) < 0)
371		goto out;
372	if ((r = vsnprintf((char *)p, len + 1, fmt, ap2)) != len) {
373		r = SSH_ERR_INTERNAL_ERROR;
374		goto out; /* Shouldn't happen */
375	}
376	/* Consume terminating \0 */
377	if ((r = sshbuf_consume_end(buf, 1)) != 0)
378		goto out;
379	r = 0;
380 out:
381	va_end(ap2);
382	return r;
383}
384
385int
386sshbuf_put_u64(struct sshbuf *buf, u_int64_t val)
387{
388	u_char *p;
389	int r;
390
391	if ((r = sshbuf_reserve(buf, 8, &p)) < 0)
392		return r;
393	POKE_U64(p, val);
394	return 0;
395}
396
397int
398sshbuf_put_u32(struct sshbuf *buf, u_int32_t val)
399{
400	u_char *p;
401	int r;
402
403	if ((r = sshbuf_reserve(buf, 4, &p)) < 0)
404		return r;
405	POKE_U32(p, val);
406	return 0;
407}
408
409int
410sshbuf_put_u16(struct sshbuf *buf, u_int16_t val)
411{
412	u_char *p;
413	int r;
414
415	if ((r = sshbuf_reserve(buf, 2, &p)) < 0)
416		return r;
417	POKE_U16(p, val);
418	return 0;
419}
420
421int
422sshbuf_put_u8(struct sshbuf *buf, u_char val)
423{
424	u_char *p;
425	int r;
426
427	if ((r = sshbuf_reserve(buf, 1, &p)) < 0)
428		return r;
429	p[0] = val;
430	return 0;
431}
432
433static int
434check_woffset(struct sshbuf *buf, size_t offset, size_t len, u_char **p)
435{
436	int r;
437
438	*p = NULL;
439	if ((r = check_offset(buf, 1, offset, len)) != 0)
440		return r;
441	if (sshbuf_mutable_ptr(buf) == NULL)
442		return SSH_ERR_BUFFER_READ_ONLY;
443	*p = sshbuf_mutable_ptr(buf) + offset;
444	return 0;
445}
446
447int
448sshbuf_poke_u64(struct sshbuf *buf, size_t offset, u_int64_t val)
449{
450	u_char *p = NULL;
451	int r;
452
453	if ((r = check_woffset(buf, offset, 8, &p)) != 0)
454		return r;
455	POKE_U64(p, val);
456	return 0;
457}
458
459int
460sshbuf_poke_u32(struct sshbuf *buf, size_t offset, u_int32_t val)
461{
462	u_char *p = NULL;
463	int r;
464
465	if ((r = check_woffset(buf, offset, 4, &p)) != 0)
466		return r;
467	POKE_U32(p, val);
468	return 0;
469}
470
471int
472sshbuf_poke_u16(struct sshbuf *buf, size_t offset, u_int16_t val)
473{
474	u_char *p = NULL;
475	int r;
476
477	if ((r = check_woffset(buf, offset, 2, &p)) != 0)
478		return r;
479	POKE_U16(p, val);
480	return 0;
481}
482
483int
484sshbuf_poke_u8(struct sshbuf *buf, size_t offset, u_char val)
485{
486	u_char *p = NULL;
487	int r;
488
489	if ((r = check_woffset(buf, offset, 1, &p)) != 0)
490		return r;
491	*p = val;
492	return 0;
493}
494
495int
496sshbuf_poke(struct sshbuf *buf, size_t offset, void *v, size_t len)
497{
498	u_char *p = NULL;
499	int r;
500
501	if ((r = check_woffset(buf, offset, len, &p)) != 0)
502		return r;
503	memcpy(p, v, len);
504	return 0;
505}
506
507int
508sshbuf_put_string(struct sshbuf *buf, const void *v, size_t len)
509{
510	u_char *d;
511	int r;
512
513	if (len > SSHBUF_SIZE_MAX - 4) {
514		SSHBUF_DBG(("SSH_ERR_NO_BUFFER_SPACE"));
515		return SSH_ERR_NO_BUFFER_SPACE;
516	}
517	if ((r = sshbuf_reserve(buf, len + 4, &d)) < 0)
518		return r;
519	POKE_U32(d, len);
520	if (len != 0)
521		memcpy(d + 4, v, len);
522	return 0;
523}
524
525int
526sshbuf_put_cstring(struct sshbuf *buf, const char *v)
527{
528	return sshbuf_put_string(buf, v, v == NULL ? 0 : strlen(v));
529}
530
531int
532sshbuf_put_stringb(struct sshbuf *buf, const struct sshbuf *v)
533{
534	if (v == NULL)
535		return sshbuf_put_string(buf, NULL, 0);
536
537	return sshbuf_put_string(buf, sshbuf_ptr(v), sshbuf_len(v));
538}
539
540int
541sshbuf_froms(struct sshbuf *buf, struct sshbuf **bufp)
542{
543	const u_char *p;
544	size_t len;
545	struct sshbuf *ret;
546	int r;
547
548	if (buf == NULL || bufp == NULL)
549		return SSH_ERR_INVALID_ARGUMENT;
550	*bufp = NULL;
551	if ((r = sshbuf_peek_string_direct(buf, &p, &len)) != 0)
552		return r;
553	if ((ret = sshbuf_from(p, len)) == NULL)
554		return SSH_ERR_ALLOC_FAIL;
555	if ((r = sshbuf_consume(buf, len + 4)) != 0 ||  /* Shouldn't happen */
556	    (r = sshbuf_set_parent(ret, buf)) != 0) {
557		sshbuf_free(ret);
558		return r;
559	}
560	*bufp = ret;
561	return 0;
562}
563
564int
565sshbuf_put_bignum2_bytes(struct sshbuf *buf, const void *v, size_t len)
566{
567	u_char *d;
568	const u_char *s = (const u_char *)v;
569	int r, prepend;
570
571	if (len > SSHBUF_SIZE_MAX - 5) {
572		SSHBUF_DBG(("SSH_ERR_NO_BUFFER_SPACE"));
573		return SSH_ERR_NO_BUFFER_SPACE;
574	}
575	/* Skip leading zero bytes */
576	for (; len > 0 && *s == 0; len--, s++)
577		;
578	/*
579	 * If most significant bit is set then prepend a zero byte to
580	 * avoid interpretation as a negative number.
581	 */
582	prepend = len > 0 && (s[0] & 0x80) != 0;
583	if ((r = sshbuf_reserve(buf, len + 4 + prepend, &d)) < 0)
584		return r;
585	POKE_U32(d, len + prepend);
586	if (prepend)
587		d[4] = 0;
588	if (len != 0)
589		memcpy(d + 4 + prepend, s, len);
590	return 0;
591}
592
593int
594sshbuf_get_bignum2_bytes_direct(struct sshbuf *buf,
595    const u_char **valp, size_t *lenp)
596{
597	const u_char *d;
598	size_t len, olen;
599	int r;
600
601	if ((r = sshbuf_peek_string_direct(buf, &d, &olen)) < 0)
602		return r;
603	len = olen;
604	/* Refuse negative (MSB set) bignums */
605	if ((len != 0 && (*d & 0x80) != 0))
606		return SSH_ERR_BIGNUM_IS_NEGATIVE;
607	/* Refuse overlong bignums, allow prepended \0 to avoid MSB set */
608	if (len > SSHBUF_MAX_BIGNUM + 1 ||
609	    (len == SSHBUF_MAX_BIGNUM + 1 && *d != 0))
610		return SSH_ERR_BIGNUM_TOO_LARGE;
611	/* Trim leading zeros */
612	while (len > 0 && *d == 0x00) {
613		d++;
614		len--;
615	}
616	if (valp != NULL)
617		*valp = d;
618	if (lenp != NULL)
619		*lenp = len;
620	if (sshbuf_consume(buf, olen + 4) != 0) {
621		/* Shouldn't happen */
622		SSHBUF_DBG(("SSH_ERR_INTERNAL_ERROR"));
623		SSHBUF_ABORT();
624		return SSH_ERR_INTERNAL_ERROR;
625	}
626	return 0;
627}
628