sshbuf-getput-basic.c revision 1.13 
1/*	$OpenBSD: sshbuf-getput-basic.c,v 1.13 2022/05/25 06:03:44 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	if (v == NULL)
338		return 0;
339	return sshbuf_put(buf, sshbuf_ptr(v), sshbuf_len(v));
340}
341
342int
343sshbuf_putf(struct sshbuf *buf, const char *fmt, ...)
344{
345	va_list ap;
346	int r;
347
348	va_start(ap, fmt);
349	r = sshbuf_putfv(buf, fmt, ap);
350	va_end(ap);
351	return r;
352}
353
354int
355sshbuf_putfv(struct sshbuf *buf, const char *fmt, va_list ap)
356{
357	va_list ap2;
358	int r, len;
359	u_char *p;
360
361	va_copy(ap2, ap);
362	if ((len = vsnprintf(NULL, 0, fmt, ap2)) < 0) {
363		r = SSH_ERR_INVALID_ARGUMENT;
364		goto out;
365	}
366	if (len == 0) {
367		r = 0;
368		goto out; /* Nothing to do */
369	}
370	va_end(ap2);
371	va_copy(ap2, ap);
372	if ((r = sshbuf_reserve(buf, (size_t)len + 1, &p)) < 0)
373		goto out;
374	if ((r = vsnprintf((char *)p, len + 1, fmt, ap2)) != len) {
375		r = SSH_ERR_INTERNAL_ERROR;
376		goto out; /* Shouldn't happen */
377	}
378	/* Consume terminating \0 */
379	if ((r = sshbuf_consume_end(buf, 1)) != 0)
380		goto out;
381	r = 0;
382 out:
383	va_end(ap2);
384	return r;
385}
386
387int
388sshbuf_put_u64(struct sshbuf *buf, u_int64_t val)
389{
390	u_char *p;
391	int r;
392
393	if ((r = sshbuf_reserve(buf, 8, &p)) < 0)
394		return r;
395	POKE_U64(p, val);
396	return 0;
397}
398
399int
400sshbuf_put_u32(struct sshbuf *buf, u_int32_t val)
401{
402	u_char *p;
403	int r;
404
405	if ((r = sshbuf_reserve(buf, 4, &p)) < 0)
406		return r;
407	POKE_U32(p, val);
408	return 0;
409}
410
411int
412sshbuf_put_u16(struct sshbuf *buf, u_int16_t val)
413{
414	u_char *p;
415	int r;
416
417	if ((r = sshbuf_reserve(buf, 2, &p)) < 0)
418		return r;
419	POKE_U16(p, val);
420	return 0;
421}
422
423int
424sshbuf_put_u8(struct sshbuf *buf, u_char val)
425{
426	u_char *p;
427	int r;
428
429	if ((r = sshbuf_reserve(buf, 1, &p)) < 0)
430		return r;
431	p[0] = val;
432	return 0;
433}
434
435static int
436check_woffset(struct sshbuf *buf, size_t offset, size_t len, u_char **p)
437{
438	int r;
439
440	*p = NULL;
441	if ((r = check_offset(buf, 1, offset, len)) != 0)
442		return r;
443	if (sshbuf_mutable_ptr(buf) == NULL)
444		return SSH_ERR_BUFFER_READ_ONLY;
445	*p = sshbuf_mutable_ptr(buf) + offset;
446	return 0;
447}
448
449int
450sshbuf_poke_u64(struct sshbuf *buf, size_t offset, u_int64_t val)
451{
452	u_char *p = NULL;
453	int r;
454
455	if ((r = check_woffset(buf, offset, 8, &p)) != 0)
456		return r;
457	POKE_U64(p, val);
458	return 0;
459}
460
461int
462sshbuf_poke_u32(struct sshbuf *buf, size_t offset, u_int32_t val)
463{
464	u_char *p = NULL;
465	int r;
466
467	if ((r = check_woffset(buf, offset, 4, &p)) != 0)
468		return r;
469	POKE_U32(p, val);
470	return 0;
471}
472
473int
474sshbuf_poke_u16(struct sshbuf *buf, size_t offset, u_int16_t val)
475{
476	u_char *p = NULL;
477	int r;
478
479	if ((r = check_woffset(buf, offset, 2, &p)) != 0)
480		return r;
481	POKE_U16(p, val);
482	return 0;
483}
484
485int
486sshbuf_poke_u8(struct sshbuf *buf, size_t offset, u_char val)
487{
488	u_char *p = NULL;
489	int r;
490
491	if ((r = check_woffset(buf, offset, 1, &p)) != 0)
492		return r;
493	*p = val;
494	return 0;
495}
496
497int
498sshbuf_poke(struct sshbuf *buf, size_t offset, void *v, size_t len)
499{
500	u_char *p = NULL;
501	int r;
502
503	if ((r = check_woffset(buf, offset, len, &p)) != 0)
504		return r;
505	memcpy(p, v, len);
506	return 0;
507}
508
509int
510sshbuf_put_string(struct sshbuf *buf, const void *v, size_t len)
511{
512	u_char *d;
513	int r;
514
515	if (len > SSHBUF_SIZE_MAX - 4) {
516		SSHBUF_DBG(("SSH_ERR_NO_BUFFER_SPACE"));
517		return SSH_ERR_NO_BUFFER_SPACE;
518	}
519	if ((r = sshbuf_reserve(buf, len + 4, &d)) < 0)
520		return r;
521	POKE_U32(d, len);
522	if (len != 0)
523		memcpy(d + 4, v, len);
524	return 0;
525}
526
527int
528sshbuf_put_cstring(struct sshbuf *buf, const char *v)
529{
530	return sshbuf_put_string(buf, v, v == NULL ? 0 : strlen(v));
531}
532
533int
534sshbuf_put_stringb(struct sshbuf *buf, const struct sshbuf *v)
535{
536	if (v == NULL)
537		return sshbuf_put_string(buf, NULL, 0);
538
539	return sshbuf_put_string(buf, sshbuf_ptr(v), sshbuf_len(v));
540}
541
542int
543sshbuf_froms(struct sshbuf *buf, struct sshbuf **bufp)
544{
545	const u_char *p;
546	size_t len;
547	struct sshbuf *ret;
548	int r;
549
550	if (buf == NULL || bufp == NULL)
551		return SSH_ERR_INVALID_ARGUMENT;
552	*bufp = NULL;
553	if ((r = sshbuf_peek_string_direct(buf, &p, &len)) != 0)
554		return r;
555	if ((ret = sshbuf_from(p, len)) == NULL)
556		return SSH_ERR_ALLOC_FAIL;
557	if ((r = sshbuf_consume(buf, len + 4)) != 0 ||  /* Shouldn't happen */
558	    (r = sshbuf_set_parent(ret, buf)) != 0) {
559		sshbuf_free(ret);
560		return r;
561	}
562	*bufp = ret;
563	return 0;
564}
565
566int
567sshbuf_put_bignum2_bytes(struct sshbuf *buf, const void *v, size_t len)
568{
569	u_char *d;
570	const u_char *s = (const u_char *)v;
571	int r, prepend;
572
573	if (len > SSHBUF_SIZE_MAX - 5) {
574		SSHBUF_DBG(("SSH_ERR_NO_BUFFER_SPACE"));
575		return SSH_ERR_NO_BUFFER_SPACE;
576	}
577	/* Skip leading zero bytes */
578	for (; len > 0 && *s == 0; len--, s++)
579		;
580	/*
581	 * If most significant bit is set then prepend a zero byte to
582	 * avoid interpretation as a negative number.
583	 */
584	prepend = len > 0 && (s[0] & 0x80) != 0;
585	if ((r = sshbuf_reserve(buf, len + 4 + prepend, &d)) < 0)
586		return r;
587	POKE_U32(d, len + prepend);
588	if (prepend)
589		d[4] = 0;
590	if (len != 0)
591		memcpy(d + 4 + prepend, s, len);
592	return 0;
593}
594
595int
596sshbuf_get_bignum2_bytes_direct(struct sshbuf *buf,
597    const u_char **valp, size_t *lenp)
598{
599	const u_char *d;
600	size_t len, olen;
601	int r;
602
603	if ((r = sshbuf_peek_string_direct(buf, &d, &olen)) < 0)
604		return r;
605	len = olen;
606	/* Refuse negative (MSB set) bignums */
607	if ((len != 0 && (*d & 0x80) != 0))
608		return SSH_ERR_BIGNUM_IS_NEGATIVE;
609	/* Refuse overlong bignums, allow prepended \0 to avoid MSB set */
610	if (len > SSHBUF_MAX_BIGNUM + 1 ||
611	    (len == SSHBUF_MAX_BIGNUM + 1 && *d != 0))
612		return SSH_ERR_BIGNUM_TOO_LARGE;
613	/* Trim leading zeros */
614	while (len > 0 && *d == 0x00) {
615		d++;
616		len--;
617	}
618	if (valp != NULL)
619		*valp = d;
620	if (lenp != NULL)
621		*lenp = len;
622	if (sshbuf_consume(buf, olen + 4) != 0) {
623		/* Shouldn't happen */
624		SSHBUF_DBG(("SSH_ERR_INTERNAL_ERROR"));
625		SSHBUF_ABORT();
626		return SSH_ERR_INTERNAL_ERROR;
627	}
628	return 0;
629}
630