crypto/openssh/sshbuf.h

   1 /*      $OpenBSD: sshbuf.h,v 1.27 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 #ifndef _SSHBUF_H
  19 #define _SSHBUF_H
  20
  21 #include <sys/types.h>
  22 #include <stdarg.h>
  23 #include <stdio.h>
  24 #ifdef WITH_OPENSSL
  25 # include <openssl/bn.h>
  26 # ifdef OPENSSL_HAS_ECC
  27 #  include <openssl/ec.h>
  28 # endif /* OPENSSL_HAS_ECC */
  29 #endif /* WITH_OPENSSL */
  30
  31 #define SSHBUF_SIZE_MAX         0x8000000       /* Hard maximum size */
  32 #define SSHBUF_REFS_MAX         0x100000        /* Max child buffers */
  33 #define SSHBUF_MAX_BIGNUM       (16384 / 8)     /* Max bignum *bytes* */
  34 #define SSHBUF_MAX_ECPOINT      ((528 * 2 / 8) + 1) /* Max EC point *bytes* */
  35
  36 /*
  37  * NB. do not depend on the internals of this. It will be made opaque
  38  * one day.
  39  */
  40 struct sshbuf {
  41         u_char *d;              /* Data */
  42         const u_char *cd;       /* Const data */
  43         size_t off;             /* First available byte is buf->d + buf->off */
  44         size_t size;            /* Last byte is buf->d + buf->size - 1 */
  45         size_t max_size;        /* Maximum size of buffer */
  46         size_t alloc;           /* Total bytes allocated to buf->d */
  47         int readonly;           /* Refers to external, const data */
  48         int dont_free;          /* Kludge to support sshbuf_init */
  49         u_int refcount;         /* Tracks self and number of child buffers */
  50         struct sshbuf *parent;  /* If child, pointer to parent */
  51 };
  52
  53 /*
  54  * Create a new sshbuf buffer.
  55  * Returns pointer to buffer on success, or NULL on allocation failure.
  56  */
  57 struct sshbuf *sshbuf_new(void);
  58
  59 /*
  60  * Create a new, read-only sshbuf buffer from existing data.
  61  * Returns pointer to buffer on success, or NULL on allocation failure.
  62  */
  63 struct sshbuf *sshbuf_from(const void *blob, size_t len);
  64
  65 /*
  66  * Create a new, read-only sshbuf buffer from the contents of an existing
  67  * buffer. The contents of "buf" must not change in the lifetime of the
  68  * resultant buffer.
  69  * Returns pointer to buffer on success, or NULL on allocation failure.
  70  */
  71 struct sshbuf *sshbuf_fromb(struct sshbuf *buf);
  72
  73 /*
  74  * Create a new, read-only sshbuf buffer from the contents of a string in
  75  * an existing buffer (the string is consumed in the process).
  76  * The contents of "buf" must not change in the lifetime of the resultant
  77  * buffer.
  78  * Returns pointer to buffer on success, or NULL on allocation failure.
  79  */
  80 int     sshbuf_froms(struct sshbuf *buf, struct sshbuf **bufp);
  81
  82 /*
  83  * Clear and free buf
  84  */
  85 void    sshbuf_free(struct sshbuf *buf);
  86
  87 /*
  88  * Reset buf, clearing its contents. NB. max_size is preserved.
  89  */
  90 void    sshbuf_reset(struct sshbuf *buf);
  91
  92 /*
  93  * Return the maximum size of buf
  94  */
  95 size_t  sshbuf_max_size(const struct sshbuf *buf);
  96
  97 /*
  98  * Set the maximum size of buf
  99  * Returns 0 on success, or a negative SSH_ERR_* error code on failure.
 100  */
 101 int     sshbuf_set_max_size(struct sshbuf *buf, size_t max_size);
 102
 103 /*
 104  * Returns the length of data in buf
 105  */
 106 size_t  sshbuf_len(const struct sshbuf *buf);
 107
 108 /*
 109  * Returns number of bytes left in buffer before hitting max_size.
 110  */
 111 size_t  sshbuf_avail(const struct sshbuf *buf);
 112
 113 /*
 114  * Returns a read-only pointer to the start of the data in buf
 115  */
 116 const u_char *sshbuf_ptr(const struct sshbuf *buf);
 117
 118 /*
 119  * Returns a mutable pointer to the start of the data in buf, or
 120  * NULL if the buffer is read-only.
 121  */
 122 u_char *sshbuf_mutable_ptr(const struct sshbuf *buf);
 123
 124 /*
 125  * Check whether a reservation of size len will succeed in buf
 126  * Safer to use than direct comparisons again sshbuf_avail as it copes
 127  * with unsigned overflows correctly.
 128  * Returns 0 on success, or a negative SSH_ERR_* error code on failure.
 129  */
 130 int     sshbuf_check_reserve(const struct sshbuf *buf, size_t len);
 131
 132 /*
 133  * Preallocates len additional bytes in buf.
 134  * Useful for cases where the caller knows how many bytes will ultimately be
 135  * required to avoid realloc in the buffer code.
 136  * Returns 0 on success, or a negative SSH_ERR_* error code on failure.
 137  */
 138 int     sshbuf_allocate(struct sshbuf *buf, size_t len);
 139
 140 /*
 141  * Reserve len bytes in buf.
 142  * Returns 0 on success and a pointer to the first reserved byte via the
 143  * optional dpp parameter or a negative SSH_ERR_* error code on failure.
 144  */
 145 int     sshbuf_reserve(struct sshbuf *buf, size_t len, u_char **dpp);
 146
 147 /*
 148  * Consume len bytes from the start of buf
 149  * Returns 0 on success, or a negative SSH_ERR_* error code on failure.
 150  */
 151 int     sshbuf_consume(struct sshbuf *buf, size_t len);
 152
 153 /*
 154  * Consume len bytes from the end of buf
 155  * Returns 0 on success, or a negative SSH_ERR_* error code on failure.
 156  */
 157 int     sshbuf_consume_end(struct sshbuf *buf, size_t len);
 158
 159 /* Extract or deposit some bytes */
 160 int     sshbuf_get(struct sshbuf *buf, void *v, size_t len);
 161 int     sshbuf_put(struct sshbuf *buf, const void *v, size_t len);
 162 int     sshbuf_putb(struct sshbuf *buf, const struct sshbuf *v);
 163
 164 /* Append using a printf(3) format */
 165 int     sshbuf_putf(struct sshbuf *buf, const char *fmt, ...)
 166             __attribute__((format(printf, 2, 3)));
 167 int     sshbuf_putfv(struct sshbuf *buf, const char *fmt, va_list ap);
 168
 169 /* Functions to extract or store big-endian words of various sizes */
 170 int     sshbuf_get_u64(struct sshbuf *buf, u_int64_t *valp);
 171 int     sshbuf_get_u32(struct sshbuf *buf, u_int32_t *valp);
 172 int     sshbuf_get_u16(struct sshbuf *buf, u_int16_t *valp);
 173 int     sshbuf_get_u8(struct sshbuf *buf, u_char *valp);
 174 int     sshbuf_put_u64(struct sshbuf *buf, u_int64_t val);
 175 int     sshbuf_put_u32(struct sshbuf *buf, u_int32_t val);
 176 int     sshbuf_put_u16(struct sshbuf *buf, u_int16_t val);
 177 int     sshbuf_put_u8(struct sshbuf *buf, u_char val);
 178
 179 /* Functions to peek at the contents of a buffer without modifying it. */
 180 int     sshbuf_peek_u64(const struct sshbuf *buf, size_t offset,
 181     u_int64_t *valp);
 182 int     sshbuf_peek_u32(const struct sshbuf *buf, size_t offset,
 183     u_int32_t *valp);
 184 int     sshbuf_peek_u16(const struct sshbuf *buf, size_t offset,
 185     u_int16_t *valp);
 186 int     sshbuf_peek_u8(const struct sshbuf *buf, size_t offset,
 187     u_char *valp);
 188
 189 /*
 190  * Functions to poke values into an existing buffer (e.g. a length header
 191  * to a packet). The destination bytes must already exist in the buffer.
 192  */
 193 int sshbuf_poke_u64(struct sshbuf *buf, size_t offset, u_int64_t val);
 194 int sshbuf_poke_u32(struct sshbuf *buf, size_t offset, u_int32_t val);
 195 int sshbuf_poke_u16(struct sshbuf *buf, size_t offset, u_int16_t val);
 196 int sshbuf_poke_u8(struct sshbuf *buf, size_t offset, u_char val);
 197 int sshbuf_poke(struct sshbuf *buf, size_t offset, void *v, size_t len);
 198
 199 /*
 200  * Functions to extract or store SSH wire encoded strings (u32 len || data)
 201  * The "cstring" variants admit no \0 characters in the string contents.
 202  * Caller must free *valp.
 203  */
 204 int     sshbuf_get_string(struct sshbuf *buf, u_char **valp, size_t *lenp);
 205 int     sshbuf_get_cstring(struct sshbuf *buf, char **valp, size_t *lenp);
 206 int     sshbuf_get_stringb(struct sshbuf *buf, struct sshbuf *v);
 207 int     sshbuf_put_string(struct sshbuf *buf, const void *v, size_t len);
 208 int     sshbuf_put_cstring(struct sshbuf *buf, const char *v);
 209 int     sshbuf_put_stringb(struct sshbuf *buf, const struct sshbuf *v);
 210
 211 /*
 212  * "Direct" variant of sshbuf_get_string, returns pointer into the sshbuf to
 213  * avoid an malloc+memcpy. The pointer is guaranteed to be valid until the
 214  * next sshbuf-modifying function call. Caller does not free.
 215  */
 216 int     sshbuf_get_string_direct(struct sshbuf *buf, const u_char **valp,
 217             size_t *lenp);
 218
 219 /* Skip past a string */
 220 #define sshbuf_skip_string(buf) sshbuf_get_string_direct(buf, NULL, NULL)
 221
 222 /* Another variant: "peeks" into the buffer without modifying it */
 223 int     sshbuf_peek_string_direct(const struct sshbuf *buf, const u_char **valp,
 224             size_t *lenp);
 225
 226 /*
 227  * Functions to extract or store SSH wire encoded bignums and elliptic
 228  * curve points.
 229  */
 230 int     sshbuf_put_bignum2_bytes(struct sshbuf *buf, const void *v, size_t len);
 231 int     sshbuf_get_bignum2_bytes_direct(struct sshbuf *buf,
 232             const u_char **valp, size_t *lenp);
 233 #ifdef WITH_OPENSSL
 234 int     sshbuf_get_bignum2(struct sshbuf *buf, BIGNUM **valp);
 235 int     sshbuf_put_bignum2(struct sshbuf *buf, const BIGNUM *v);
 236 # ifdef OPENSSL_HAS_ECC
 237 int     sshbuf_get_ec(struct sshbuf *buf, EC_POINT *v, const EC_GROUP *g);
 238 int     sshbuf_get_eckey(struct sshbuf *buf, EC_KEY *v);
 239 int     sshbuf_put_ec(struct sshbuf *buf, const EC_POINT *v, const EC_GROUP *g);
 240 int     sshbuf_put_eckey(struct sshbuf *buf, const EC_KEY *v);
 241 # endif /* OPENSSL_HAS_ECC */
 242 #endif /* WITH_OPENSSL */
 243
 244 /* Dump the contents of the buffer in a human-readable format */
 245 void    sshbuf_dump(const struct sshbuf *buf, FILE *f);
 246
 247 /* Dump specified memory in a human-readable format */
 248 void    sshbuf_dump_data(const void *s, size_t len, FILE *f);
 249
 250 /* Return the hexadecimal representation of the contents of the buffer */
 251 char    *sshbuf_dtob16(struct sshbuf *buf);
 252
 253 /* Encode the contents of the buffer as base64 */
 254 char    *sshbuf_dtob64_string(const struct sshbuf *buf, int wrap);
 255 int     sshbuf_dtob64(const struct sshbuf *d, struct sshbuf *b64, int wrap);
 256 /* RFC4648 "base64url" encoding variant */
 257 int     sshbuf_dtourlb64(const struct sshbuf *d, struct sshbuf *b64, int wrap);
 258
 259 /* Decode base64 data and append it to the buffer */
 260 int     sshbuf_b64tod(struct sshbuf *buf, const char *b64);
 261
 262 /*
 263  * Tests whether the buffer contains the specified byte sequence at the
 264  * specified offset. Returns 0 on successful match, or a ssherr.h code
 265  * otherwise. SSH_ERR_INVALID_FORMAT indicates sufficient bytes were
 266  * present but the buffer contents did not match those supplied. Zero-
 267  * length comparisons are not allowed.
 268  *
 269  * If sufficient data is present to make a comparison, then it is
 270  * performed with timing independent of the value of the data. If
 271  * insufficient data is present then the comparison is not attempted at
 272  * all.
 273  */
 274 int     sshbuf_cmp(const struct sshbuf *b, size_t offset,
 275     const void *s, size_t len);
 276
 277 /*
 278  * Searches the buffer for the specified string. Returns 0 on success
 279  * and updates *offsetp with the offset of the first match, relative to
 280  * the start of the buffer. Otherwise sshbuf_find will return a ssherr.h
 281  * error code. SSH_ERR_INVALID_FORMAT indicates sufficient bytes were
 282  * present in the buffer for a match to be possible but none was found.
 283  * Searches for zero-length data are not allowed.
 284  */
 285 int
 286 sshbuf_find(const struct sshbuf *b, size_t start_offset,
 287     const void *s, size_t len, size_t *offsetp);
 288
 289 /*
 290  * Duplicate the contents of a buffer to a string (caller to free).
 291  * Returns NULL on buffer error, or if the buffer contains a premature
 292  * nul character.
 293  */
 294 char *sshbuf_dup_string(struct sshbuf *buf);
 295
 296 /*
 297  * Fill a buffer from a file descriptor or filename. Both allocate the
 298  * buffer for the caller.
 299  */
 300 int sshbuf_load_fd(int, struct sshbuf **)
 301     __attribute__((__nonnull__ (2)));
 302 int sshbuf_load_file(const char *, struct sshbuf **)
 303     __attribute__((__nonnull__ (2)));
 304
 305 /*
 306  * Write a buffer to a path, creating/truncating as needed (mode 0644,
 307  * subject to umask). The buffer contents are not modified.
 308  */
 309 int sshbuf_write_file(const char *path, struct sshbuf *buf)
 310     __attribute__((__nonnull__ (2)));
 311
 312 /* Read up to maxlen bytes from a fd directly to a buffer */
 313 int sshbuf_read(int, struct sshbuf *, size_t, size_t *)
 314     __attribute__((__nonnull__ (2)));
 315
 316 /* Macros for decoding/encoding integers */
 317 #define PEEK_U64(p) \
 318         (((u_int64_t)(((const u_char *)(p))[0]) << 56) | \
 319          ((u_int64_t)(((const u_char *)(p))[1]) << 48) | \
 320          ((u_int64_t)(((const u_char *)(p))[2]) << 40) | \
 321          ((u_int64_t)(((const u_char *)(p))[3]) << 32) | \
 322          ((u_int64_t)(((const u_char *)(p))[4]) << 24) | \
 323          ((u_int64_t)(((const u_char *)(p))[5]) << 16) | \
 324          ((u_int64_t)(((const u_char *)(p))[6]) << 8) | \
 325           (u_int64_t)(((const u_char *)(p))[7]))
 326 #define PEEK_U32(p) \
 327         (((u_int32_t)(((const u_char *)(p))[0]) << 24) | \
 328          ((u_int32_t)(((const u_char *)(p))[1]) << 16) | \
 329          ((u_int32_t)(((const u_char *)(p))[2]) << 8) | \
 330           (u_int32_t)(((const u_char *)(p))[3]))
 331 #define PEEK_U16(p) \
 332         (((u_int16_t)(((const u_char *)(p))[0]) << 8) | \
 333           (u_int16_t)(((const u_char *)(p))[1]))
 334
 335 #define POKE_U64(p, v) \
 336         do { \
 337                 const u_int64_t __v = (v); \
 338                 ((u_char *)(p))[0] = (__v >> 56) & 0xff; \
 339                 ((u_char *)(p))[1] = (__v >> 48) & 0xff; \
 340                 ((u_char *)(p))[2] = (__v >> 40) & 0xff; \
 341                 ((u_char *)(p))[3] = (__v >> 32) & 0xff; \
 342                 ((u_char *)(p))[4] = (__v >> 24) & 0xff; \
 343                 ((u_char *)(p))[5] = (__v >> 16) & 0xff; \
 344                 ((u_char *)(p))[6] = (__v >> 8) & 0xff; \
 345                 ((u_char *)(p))[7] = __v & 0xff; \
 346         } while (0)
 347 #define POKE_U32(p, v) \
 348         do { \
 349                 const u_int32_t __v = (v); \
 350                 ((u_char *)(p))[0] = (__v >> 24) & 0xff; \
 351                 ((u_char *)(p))[1] = (__v >> 16) & 0xff; \
 352                 ((u_char *)(p))[2] = (__v >> 8) & 0xff; \
 353                 ((u_char *)(p))[3] = __v & 0xff; \
 354         } while (0)
 355 #define POKE_U16(p, v) \
 356         do { \
 357                 const u_int16_t __v = (v); \
 358                 ((u_char *)(p))[0] = (__v >> 8) & 0xff; \
 359                 ((u_char *)(p))[1] = __v & 0xff; \
 360         } while (0)
 361
 362 /* Internal definitions follow. Exposed for regress tests */
 363 #ifdef SSHBUF_INTERNAL
 364
 365 /*
 366  * Return the allocation size of buf
 367  */
 368 size_t  sshbuf_alloc(const struct sshbuf *buf);
 369
 370 /*
 371  * Increment the reference count of buf.
 372  */
 373 int     sshbuf_set_parent(struct sshbuf *child, struct sshbuf *parent);
 374
 375 /*
 376  * Return the parent buffer of buf, or NULL if it has no parent.
 377  */
 378 const struct sshbuf *sshbuf_parent(const struct sshbuf *buf);
 379
 380 /*
 381  * Return the reference count of buf
 382  */
 383 u_int   sshbuf_refcount(const struct sshbuf *buf);
 384
 385 # define SSHBUF_SIZE_INIT       256             /* Initial allocation */
 386 # define SSHBUF_SIZE_INC        256             /* Preferred increment length */
 387 # define SSHBUF_PACK_MIN        8192            /* Minimum packable offset */
 388
 389 /* # define SSHBUF_ABORT abort */
 390 /* # define SSHBUF_DEBUG */
 391
 392 # ifndef SSHBUF_ABORT
 393 #  define SSHBUF_ABORT()
 394 # endif
 395
 396 # ifdef SSHBUF_DEBUG
 397 #  define SSHBUF_TELL(what) do { \
 398                 printf("%s:%d %s: %s size %zu alloc %zu off %zu max %zu\n", \
 399                     __FILE__, __LINE__, __func__, what, \
 400                     buf->size, buf->alloc, buf->off, buf->max_size); \
 401                 fflush(stdout); \
 402         } while (0)
 403 #  define SSHBUF_DBG(x) do { \
 404                 printf("%s:%d %s: ", __FILE__, __LINE__, __func__); \
 405                 printf x; \
 406                 printf("\n"); \
 407                 fflush(stdout); \
 408         } while (0)
 409 # else
 410 #  define SSHBUF_TELL(what)
 411 #  define SSHBUF_DBG(x)
 412 # endif
 413 #endif /* SSHBUF_INTERNAL */
 414
 415 #endif /* _SSHBUF_H */