summaryrefslogtreecommitdiffstats
path: root/sshbuf.h
blob: 2ad0e61be120d9d657b9b124618ad4a21b0ae78f (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
/*	$OpenBSD: sshbuf.h,v 1.23 2020/06/22 05:54:10 djm Exp $	*/
/*
 * Copyright (c) 2011 Damien Miller
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#ifndef _SSHBUF_H
#define _SSHBUF_H

#include <sys/types.h>
#include <stdarg.h>
#include <stdio.h>
#ifdef WITH_OPENSSL
# include <openssl/bn.h>
# ifdef OPENSSL_HAS_ECC
#  include <openssl/ec.h>
# endif /* OPENSSL_HAS_ECC */
#endif /* WITH_OPENSSL */

#define SSHBUF_SIZE_MAX		0x8000000	/* Hard maximum size */
#define SSHBUF_REFS_MAX		0x100000	/* Max child buffers */
#define SSHBUF_MAX_BIGNUM	(16384 / 8)	/* Max bignum *bytes* */
#define SSHBUF_MAX_ECPOINT	((528 * 2 / 8) + 1) /* Max EC point *bytes* */

/*
 * NB. do not depend on the internals of this. It will be made opaque
 * one day.
 */
struct sshbuf {
	u_char *d;		/* Data */
	const u_char *cd;	/* Const data */
	size_t off;		/* First available byte is buf->d + buf->off */
	size_t size;		/* Last byte is buf->d + buf->size - 1 */
	size_t max_size;	/* Maximum size of buffer */
	size_t alloc;		/* Total bytes allocated to buf->d */
	int readonly;		/* Refers to external, const data */
	int dont_free;		/* Kludge to support sshbuf_init */
	u_int refcount;		/* Tracks self and number of child buffers */
	struct sshbuf *parent;	/* If child, pointer to parent */
};

/*
 * Create a new sshbuf buffer.
 * Returns pointer to buffer on success, or NULL on allocation failure.
 */
struct sshbuf *sshbuf_new(void);

/*
 * Create a new, read-only sshbuf buffer from existing data.
 * Returns pointer to buffer on success, or NULL on allocation failure.
 */
struct sshbuf *sshbuf_from(const void *blob, size_t len);

/*
 * Create a new, read-only sshbuf buffer from the contents of an existing
 * buffer. The contents of "buf" must not change in the lifetime of the
 * resultant buffer.
 * Returns pointer to buffer on success, or NULL on allocation failure.
 */
struct sshbuf *sshbuf_fromb(struct sshbuf *buf);

/*
 * Create a new, read-only sshbuf buffer from the contents of a string in
 * an existing buffer (the string is consumed in the process).
 * The contents of "buf" must not change in the lifetime of the resultant
 * buffer.
 * Returns pointer to buffer on success, or NULL on allocation failure.
 */
int	sshbuf_froms(struct sshbuf *buf, struct sshbuf **bufp);

/*
 * Clear and free buf
 */
void	sshbuf_free(struct sshbuf *buf);

/*
 * Reset buf, clearing its contents. NB. max_size is preserved.
 */
void	sshbuf_reset(struct sshbuf *buf);

/*
 * Return the maximum size of buf
 */
size_t	sshbuf_max_size(const struct sshbuf *buf);

/*
 * Set the maximum size of buf
 * Returns 0 on success, or a negative SSH_ERR_* error code on failure.
 */
int	sshbuf_set_max_size(struct sshbuf *buf, size_t max_size);

/*
 * Returns the length of data in buf
 */
size_t	sshbuf_len(const struct sshbuf *buf);

/*
 * Returns number of bytes left in buffer before hitting max_size.
 */
size_t	sshbuf_avail(const struct sshbuf *buf);

/*
 * Returns a read-only pointer to the start of the data in buf
 */
const u_char *sshbuf_ptr(const struct sshbuf *buf);

/*
 * Returns a mutable pointer to the start of the data in buf, or
 * NULL if the buffer is read-only.
 */
u_char *sshbuf_mutable_ptr(const struct sshbuf *buf);

/*
 * Check whether a reservation of size len will succeed in buf
 * Safer to use than direct comparisons again sshbuf_avail as it copes
 * with unsigned overflows correctly.
 * Returns 0 on success, or a negative SSH_ERR_* error code on failure.
 */
int	sshbuf_check_reserve(const struct sshbuf *buf, size_t len);

/*
 * Preallocates len additional bytes in buf.
 * Useful for cases where the caller knows how many bytes will ultimately be
 * required to avoid realloc in the buffer code.
 * Returns 0 on success, or a negative SSH_ERR_* error code on failure.
 */
int	sshbuf_allocate(struct sshbuf *buf, size_t len);

/*
 * Reserve len bytes in buf.
 * Returns 0 on success and a pointer to the first reserved byte via the
 * optional dpp parameter or a negative SSH_ERR_* error code on failure.
 */
int	sshbuf_reserve(struct sshbuf *buf, size_t len, u_char **dpp);

/*
 * Consume len bytes from the start of buf
 * Returns 0 on success, or a negative SSH_ERR_* error code on failure.
 */
int	sshbuf_consume(struct sshbuf *buf, size_t len);

/*
 * Consume len bytes from the end of buf
 * Returns 0 on success, or a negative SSH_ERR_* error code on failure.
 */
int	sshbuf_consume_end(struct sshbuf *buf, size_t len);

/* Extract or deposit some bytes */
int	sshbuf_get(struct sshbuf *buf, void *v, size_t len);
int	sshbuf_put(struct sshbuf *buf, const void *v, size_t len);
int	sshbuf_putb(struct sshbuf *buf, const struct sshbuf *v);

/* Append using a printf(3) format */
int	sshbuf_putf(struct sshbuf *buf, const char *fmt, ...)
	    __attribute__((format(printf, 2, 3)));
int	sshbuf_putfv(struct sshbuf *buf, const char *fmt, va_list ap);

/* Functions to extract or store big-endian words of various sizes */
int	sshbuf_get_u64(struct sshbuf *buf, u_int64_t *valp);
int	sshbuf_get_u32(struct sshbuf *buf, u_int32_t *valp);
int	sshbuf_get_u16(struct sshbuf *buf, u_int16_t *valp);
int	sshbuf_get_u8(struct sshbuf *buf, u_char *valp);
int	sshbuf_put_u64(struct sshbuf *buf, u_int64_t val);
int	sshbuf_put_u32(struct sshbuf *buf, u_int32_t val);
int	sshbuf_put_u16(struct sshbuf *buf, u_int16_t val);
int	sshbuf_put_u8(struct sshbuf *buf, u_char val);

/* Functions to peek at the contents of a buffer without modifying it. */
int	sshbuf_peek_u64(const struct sshbuf *buf, size_t offset,
    u_int64_t *valp);
int	sshbuf_peek_u32(const struct sshbuf *buf, size_t offset,
    u_int32_t *valp);
int	sshbuf_peek_u16(const struct sshbuf *buf, size_t offset,
    u_int16_t *valp);
int	sshbuf_peek_u8(const struct sshbuf *buf, size_t offset,
    u_char *valp);

/*
 * Functions to poke values into an existing buffer (e.g. a length header
 * to a packet). The destination bytes must already exist in the buffer.
 */
int sshbuf_poke_u64(struct sshbuf *buf, size_t offset, u_int64_t val);
int sshbuf_poke_u32(struct sshbuf *buf, size_t offset, u_int32_t val);
int sshbuf_poke_u16(struct sshbuf *buf, size_t offset, u_int16_t val);
int sshbuf_poke_u8(struct sshbuf *buf, size_t offset, u_char val);
int sshbuf_poke(struct sshbuf *buf, size_t offset, void *v, size_t len);

/*
 * Functions to extract or store SSH wire encoded strings (u32 len || data)
 * The "cstring" variants admit no \0 characters in the string contents.
 * Caller must free *valp.
 */
int	sshbuf_get_string(struct sshbuf *buf, u_char **valp, size_t *lenp);
int	sshbuf_get_cstring(struct sshbuf *buf, char **valp, size_t *lenp);
int	sshbuf_get_stringb(struct sshbuf *buf, struct sshbuf *v);
int	sshbuf_put_string(struct sshbuf *buf, const void *v, size_t len);
int	sshbuf_put_cstring(struct sshbuf *buf, const char *v);
int	sshbuf_put_stringb(struct sshbuf *buf, const struct sshbuf *v);

/*
 * "Direct" variant of sshbuf_get_string, returns pointer into the sshbuf to
 * avoid an malloc+memcpy. The pointer is guaranteed to be valid until the
 * next sshbuf-modifying function call. Caller does not free.
 */
int	sshbuf_get_string_direct(struct sshbuf *buf, const u_char **valp,
	    size_t *lenp);

/* Skip past a string */
#define sshbuf_skip_string(buf) sshbuf_get_string_direct(buf, NULL, NULL)

/* Another variant: "peeks" into the buffer without modifying it */
int	sshbuf_peek_string_direct(const struct sshbuf *buf, const u_char **valp,
	    size_t *lenp);

/*
 * Functions to extract or store SSH wire encoded bignums and elliptic
 * curve points.
 */
int	sshbuf_put_bignum2_bytes(struct sshbuf *buf, const void *v, size_t len);
int	sshbuf_get_bignum2_bytes_direct(struct sshbuf *buf,
	    const u_char **valp, size_t *lenp);
#ifdef WITH_OPENSSL
int	sshbuf_get_bignum2(struct sshbuf *buf, BIGNUM **valp);
int	sshbuf_put_bignum2(struct sshbuf *buf, const BIGNUM *v);
# ifdef OPENSSL_HAS_ECC
int	sshbuf_get_ec(struct sshbuf *buf, EC_POINT *v, const EC_GROUP *g);
int	sshbuf_get_eckey(struct sshbuf *buf, EC_KEY *v);
int	sshbuf_put_ec(struct sshbuf *buf, const EC_POINT *v, const EC_GROUP *g);
int	sshbuf_put_eckey(struct sshbuf *buf, const EC_KEY *v);
# endif /* OPENSSL_HAS_ECC */
#endif /* WITH_OPENSSL */

/* Dump the contents of the buffer in a human-readable format */
void	sshbuf_dump(const struct sshbuf *buf, FILE *f);

/* Dump specified memory in a human-readable format */
void	sshbuf_dump_data(const void *s, size_t len, FILE *f);

/* Return the hexadecimal representation of the contents of the buffer */
char	*sshbuf_dtob16(struct sshbuf *buf);

/* Encode the contents of the buffer as base64 */
char	*sshbuf_dtob64_string(const struct sshbuf *buf, int wrap);
int	sshbuf_dtob64(const struct sshbuf *d, struct sshbuf *b64, int wrap);
/* RFC4648 "base64url" encoding variant */
int	sshbuf_dtourlb64(const struct sshbuf *d, struct sshbuf *b64, int wrap);

/* Decode base64 data and append it to the buffer */
int	sshbuf_b64tod(struct sshbuf *buf, const char *b64);

/*
 * Tests whether the buffer contains the specified byte sequence at the
 * specified offset. Returns 0 on successful match, or a ssherr.h code
 * otherwise. SSH_ERR_INVALID_FORMAT indicates sufficient bytes were
 * present but the buffer contents did not match those supplied. Zero-
 * length comparisons are not allowed.
 *
 * If sufficient data is present to make a comparison, then it is
 * performed with timing independent of the value of the data. If
 * insufficient data is present then the comparison is not attempted at
 * all.
 */
int	sshbuf_cmp(const struct sshbuf *b, size_t offset,
    const void *s, size_t len);

/*
 * Searches the buffer for the specified string. Returns 0 on success
 * and updates *offsetp with the offset of the first match, relative to
 * the start of the buffer. Otherwise sshbuf_find will return a ssherr.h
 * error code. SSH_ERR_INVALID_FORMAT indicates sufficient bytes were
 * present in the buffer for a match to be possible but none was found.
 * Searches for zero-length data are not allowed.
 */
int
sshbuf_find(const struct sshbuf *b, size_t start_offset,
    const void *s, size_t len, size_t *offsetp);

/*
 * Duplicate the contents of a buffer to a string (caller to free).
 * Returns NULL on buffer error, or if the buffer contains a premature
 * nul character.
 */
char *sshbuf_dup_string(struct sshbuf *buf);

/*
 * Fill a buffer from a file descriptor or filename. Both allocate the
 * buffer for the caller.
 */
int sshbuf_load_fd(int, struct sshbuf **)
    __attribute__((__nonnull__ (2)));
int sshbuf_load_file(const char *, struct sshbuf **)
    __attribute__((__nonnull__ (2)));

/*
 * Write a buffer to a path, creating/truncating as needed (mode 0644,
 * subject to umask). The buffer contents are not modified.
 */
int sshbuf_write_file(const char *path, struct sshbuf *buf)
    __attribute__((__nonnull__ (2)));

/* Macros for decoding/encoding integers */
#define PEEK_U64(p) \
	(((u_int64_t)(((const u_char *)(p))[0]) << 56) | \
	 ((u_int64_t)(((const u_char *)(p))[1]) << 48) | \
	 ((u_int64_t)(((const u_char *)(p))[2]) << 40) | \
	 ((u_int64_t)(((const u_char *)(p))[3]) << 32) | \
	 ((u_int64_t)(((const u_char *)(p))[4]) << 24) | \
	 ((u_int64_t)(((const u_char *)(p))[5]) << 16) | \
	 ((u_int64_t)(((const u_char *)(p))[6]) << 8) | \
	  (u_int64_t)(((const u_char *)(p))[7]))
#define PEEK_U32(p) \
	(((u_int32_t)(((const u_char *)(p))[0]) << 24) | \
	 ((u_int32_t)(((const u_char *)(p))[1]) << 16) | \
	 ((u_int32_t)(((const u_char *)(p))[2]) << 8) | \
	  (u_int32_t)(((const u_char *)(p))[3]))
#define PEEK_U16(p) \
	(((u_int16_t)(((const u_char *)(p))[0]) << 8) | \
	  (u_int16_t)(((const u_char *)(p))[1]))

#define POKE_U64(p, v) \
	do { \
		const u_int64_t __v = (v); \
		((u_char *)(p))[0] = (__v >> 56) & 0xff; \
		((u_char *)(p))[1] = (__v >> 48) & 0xff; \
		((u_char *)(p))[2] = (__v >> 40) & 0xff; \
		((u_char *)(p))[3] = (__v >> 32) & 0xff; \
		((u_char *)(p))[4] = (__v >> 24) & 0xff; \
		((u_char *)(p))[5] = (__v >> 16) & 0xff; \
		((u_char *)(p))[6] = (__v >> 8) & 0xff; \
		((u_char *)(p))[7] = __v & 0xff; \
	} while (0)
#define POKE_U32(p, v) \
	do { \
		const u_int32_t __v = (v); \
		((u_char *)(p))[0] = (__v >> 24) & 0xff; \
		((u_char *)(p))[1] = (__v >> 16) & 0xff; \
		((u_char *)(p))[2] = (__v >> 8) & 0xff; \
		((u_char *)(p))[3] = __v & 0xff; \
	} while (0)
#define POKE_U16(p, v) \
	do { \
		const u_int16_t __v = (v); \
		((u_char *)(p))[0] = (__v >> 8) & 0xff; \
		((u_char *)(p))[1] = __v & 0xff; \
	} while (0)

/* Internal definitions follow. Exposed for regress tests */
#ifdef SSHBUF_INTERNAL

/*
 * Return the allocation size of buf
 */
size_t	sshbuf_alloc(const struct sshbuf *buf);

/*
 * Increment the reference count of buf.
 */
int	sshbuf_set_parent(struct sshbuf *child, struct sshbuf *parent);

/*
 * Return the parent buffer of buf, or NULL if it has no parent.
 */
const struct sshbuf *sshbuf_parent(const struct sshbuf *buf);

/*
 * Return the reference count of buf
 */
u_int	sshbuf_refcount(const struct sshbuf *buf);

# define SSHBUF_SIZE_INIT	256		/* Initial allocation */
# define SSHBUF_SIZE_INC	256		/* Preferred increment length */
# define SSHBUF_PACK_MIN	8192		/* Minimim packable offset */

/* # define SSHBUF_ABORT abort */
/* # define SSHBUF_DEBUG */

# ifndef SSHBUF_ABORT
#  define SSHBUF_ABORT()
# endif

# ifdef SSHBUF_DEBUG
#  define SSHBUF_TELL(what) do { \
		printf("%s:%d %s: %s size %zu alloc %zu off %zu max %zu\n", \
		    __FILE__, __LINE__, __func__, what, \
		    buf->size, buf->alloc, buf->off, buf->max_size); \
		fflush(stdout); \
	} while (0)
#  define SSHBUF_DBG(x) do { \
		printf("%s:%d %s: ", __FILE__, __LINE__, __func__); \
		printf x; \
		printf("\n"); \
		fflush(stdout); \
	} while (0)
# else
#  define SSHBUF_TELL(what)
#  define SSHBUF_DBG(x)
# endif
#endif /* SSHBUF_INTERNAL */

#endif /* _SSHBUF_H */