crypto/evp/bio_enc.c

   1 /*
   2  * Copyright 1995-2024 The OpenSSL Project Authors. All Rights Reserved.
   3  *
   4  * Licensed under the Apache License 2.0 (the "License").  You may not use
   5  * this file except in compliance with the License.  You can obtain a copy
   6  * in the file LICENSE in the source distribution or at
   7  * https://www.openssl.org/source/license.html
   8  */
   9
  10 #define OPENSSL_SUPPRESS_DEPRECATED /* for BIO_get_callback */
  11
  12 #include <stdio.h>
  13 #include <errno.h>
  14 #include "internal/cryptlib.h"
  15 #include <openssl/buffer.h>
  16 #include <openssl/evp.h>
  17 #include "internal/bio.h"
  18
  19 static int enc_write(BIO *h, const char *buf, int num);
  20 static int enc_read(BIO *h, char *buf, int size);
  21 static long enc_ctrl(BIO *h, int cmd, long arg1, void *arg2);
  22 static int enc_new(BIO *h);
  23 static int enc_free(BIO *data);
  24 static long enc_callback_ctrl(BIO *h, int cmd, BIO_info_cb *fps);
  25 #define ENC_BLOCK_SIZE  (1024*4)
  26 #define ENC_MIN_CHUNK   (256)
  27 #define BUF_OFFSET      (ENC_MIN_CHUNK + EVP_MAX_BLOCK_LENGTH)
  28
  29 typedef struct enc_struct {
  30     int buf_len;
  31     int buf_off;
  32     int cont;                   /* <= 0 when finished */
  33     int finished;
  34     int ok;                     /* bad decrypt */
  35     EVP_CIPHER_CTX *cipher;
  36     unsigned char *read_start, *read_end;
  37     /*
  38      * buf is larger than ENC_BLOCK_SIZE because EVP_DecryptUpdate can return
  39      * up to a block more data than is presented to it
  40      */
  41     unsigned char buf[BUF_OFFSET + ENC_BLOCK_SIZE];
  42 } BIO_ENC_CTX;
  43
  44 static const BIO_METHOD methods_enc = {
  45     BIO_TYPE_CIPHER,
  46     "cipher",
  47     bwrite_conv,
  48     enc_write,
  49     bread_conv,
  50     enc_read,
  51     NULL,                       /* enc_puts, */
  52     NULL,                       /* enc_gets, */
  53     enc_ctrl,
  54     enc_new,
  55     enc_free,
  56     enc_callback_ctrl,
  57 };
  58
  59 const BIO_METHOD *BIO_f_cipher(void)
  60 {
  61     return &methods_enc;
  62 }
  63
  64 static int enc_new(BIO *bi)
  65 {
  66     BIO_ENC_CTX *ctx;
  67
  68     if ((ctx = OPENSSL_zalloc(sizeof(*ctx))) == NULL)
  69         return 0;
  70
  71     ctx->cipher = EVP_CIPHER_CTX_new();
  72     if (ctx->cipher == NULL) {
  73         OPENSSL_free(ctx);
  74         return 0;
  75     }
  76     ctx->cont = 1;
  77     ctx->ok = 1;
  78     ctx->read_end = ctx->read_start = &(ctx->buf[BUF_OFFSET]);
  79     BIO_set_data(bi, ctx);
  80     BIO_set_init(bi, 1);
  81
  82     return 1;
  83 }
  84
  85 static int enc_free(BIO *a)
  86 {
  87     BIO_ENC_CTX *b;
  88
  89     if (a == NULL)
  90         return 0;
  91
  92     b = BIO_get_data(a);
  93     if (b == NULL)
  94         return 0;
  95
  96     EVP_CIPHER_CTX_free(b->cipher);
  97     OPENSSL_clear_free(b, sizeof(BIO_ENC_CTX));
  98     BIO_set_data(a, NULL);
  99     BIO_set_init(a, 0);
 100
 101     return 1;
 102 }
 103
 104 static int enc_read(BIO *b, char *out, int outl)
 105 {
 106     int ret = 0, i, blocksize;
 107     BIO_ENC_CTX *ctx;
 108     BIO *next;
 109
 110     if (out == NULL)
 111         return 0;
 112     ctx = BIO_get_data(b);
 113
 114     next = BIO_next(b);
 115     if ((ctx == NULL) || (next == NULL))
 116         return 0;
 117
 118     /* First check if there are bytes decoded/encoded */
 119     if (ctx->buf_len > 0) {
 120         i = ctx->buf_len - ctx->buf_off;
 121         if (i > outl)
 122             i = outl;
 123         memcpy(out, &(ctx->buf[ctx->buf_off]), i);
 124         ret = i;
 125         out += i;
 126         outl -= i;
 127         ctx->buf_off += i;
 128         if (ctx->buf_len == ctx->buf_off) {
 129             ctx->buf_len = 0;
 130             ctx->buf_off = 0;
 131         }
 132     }
 133
 134     blocksize = EVP_CIPHER_CTX_get_block_size(ctx->cipher);
 135
 136     if (blocksize == 0)
 137         return 0;
 138
 139     if (blocksize == 1)
 140         blocksize = 0;
 141
 142     /*
 143      * At this point, we have room of outl bytes and an empty buffer, so we
 144      * should read in some more.
 145      */
 146
 147     while (outl > 0) {
 148         if (ctx->cont <= 0)
 149             break;
 150
 151         if (ctx->read_start == ctx->read_end) { /* time to read more data */
 152             ctx->read_end = ctx->read_start = &(ctx->buf[BUF_OFFSET]);
 153             i = BIO_read(next, ctx->read_start, ENC_BLOCK_SIZE);
 154             if (i > 0)
 155                 ctx->read_end += i;
 156         } else {
 157             i = ctx->read_end - ctx->read_start;
 158         }
 159
 160         if (i <= 0) {
 161             /* Should be continue next time we are called? */
 162             if (!BIO_should_retry(next)) {
 163                 ctx->cont = i;
 164                 i = EVP_CipherFinal_ex(ctx->cipher,
 165                                        ctx->buf, &(ctx->buf_len));
 166                 ctx->ok = i;
 167                 ctx->buf_off = 0;
 168             } else {
 169                 ret = (ret == 0) ? i : ret;
 170                 break;
 171             }
 172         } else {
 173             if (outl > ENC_MIN_CHUNK) {
 174                 /*
 175                  * Depending on flags block cipher decrypt can write
 176                  * one extra block and then back off, i.e. output buffer
 177                  * has to accommodate extra block...
 178                  */
 179                 int j = outl - blocksize, buf_len;
 180
 181                 if (!EVP_CipherUpdate(ctx->cipher,
 182                                       (unsigned char *)out, &buf_len,
 183                                       ctx->read_start, i > j ? j : i)) {
 184                     BIO_clear_retry_flags(b);
 185                     return 0;
 186                 }
 187                 ret += buf_len;
 188                 out += buf_len;
 189                 outl -= buf_len;
 190
 191                 if ((i -= j) <= 0) {
 192                     ctx->read_start = ctx->read_end;
 193                     continue;
 194                 }
 195                 ctx->read_start += j;
 196             }
 197             if (i > ENC_MIN_CHUNK)
 198                 i = ENC_MIN_CHUNK;
 199             if (!EVP_CipherUpdate(ctx->cipher,
 200                                   ctx->buf, &ctx->buf_len,
 201                                   ctx->read_start, i)) {
 202                 BIO_clear_retry_flags(b);
 203                 ctx->ok = 0;
 204                 return 0;
 205             }
 206             ctx->read_start += i;
 207             ctx->cont = 1;
 208             /*
 209              * Note: it is possible for EVP_CipherUpdate to decrypt zero
 210              * bytes because this is or looks like the final block: if this
 211              * happens we should retry and either read more data or decrypt
 212              * the final block
 213              */
 214             if (ctx->buf_len == 0)
 215                 continue;
 216         }
 217
 218         if (ctx->buf_len <= outl)
 219             i = ctx->buf_len;
 220         else
 221             i = outl;
 222         if (i <= 0)
 223             break;
 224         memcpy(out, ctx->buf, i);
 225         ret += i;
 226         ctx->buf_off = i;
 227         outl -= i;
 228         out += i;
 229     }
 230
 231     BIO_clear_retry_flags(b);
 232     BIO_copy_next_retry(b);
 233     return ((ret == 0) ? ctx->cont : ret);
 234 }
 235
 236 static int enc_write(BIO *b, const char *in, int inl)
 237 {
 238     int ret = 0, n, i;
 239     BIO_ENC_CTX *ctx;
 240     BIO *next;
 241
 242     ctx = BIO_get_data(b);
 243     next = BIO_next(b);
 244     if ((ctx == NULL) || (next == NULL))
 245         return 0;
 246
 247     ret = inl;
 248
 249     BIO_clear_retry_flags(b);
 250     n = ctx->buf_len - ctx->buf_off;
 251     while (n > 0) {
 252         i = BIO_write(next, &(ctx->buf[ctx->buf_off]), n);
 253         if (i <= 0) {
 254             BIO_copy_next_retry(b);
 255             return i;
 256         }
 257         ctx->buf_off += i;
 258         n -= i;
 259     }
 260     /* at this point all pending data has been written */
 261
 262     if ((in == NULL) || (inl <= 0))
 263         return 0;
 264
 265     ctx->buf_off = 0;
 266     while (inl > 0) {
 267         n = (inl > ENC_BLOCK_SIZE) ? ENC_BLOCK_SIZE : inl;
 268         if (!EVP_CipherUpdate(ctx->cipher,
 269                               ctx->buf, &ctx->buf_len,
 270                               (const unsigned char *)in, n)) {
 271             BIO_clear_retry_flags(b);
 272             ctx->ok = 0;
 273             return 0;
 274         }
 275         inl -= n;
 276         in += n;
 277
 278         ctx->buf_off = 0;
 279         n = ctx->buf_len;
 280         while (n > 0) {
 281             i = BIO_write(next, &(ctx->buf[ctx->buf_off]), n);
 282             if (i <= 0) {
 283                 BIO_copy_next_retry(b);
 284                 return (ret == inl) ? i : ret - inl;
 285             }
 286             n -= i;
 287             ctx->buf_off += i;
 288         }
 289         ctx->buf_len = 0;
 290         ctx->buf_off = 0;
 291     }
 292     BIO_copy_next_retry(b);
 293     return ret;
 294 }
 295
 296 static long enc_ctrl(BIO *b, int cmd, long num, void *ptr)
 297 {
 298     BIO *dbio;
 299     BIO_ENC_CTX *ctx, *dctx;
 300     long ret = 1;
 301     int i;
 302     EVP_CIPHER_CTX **c_ctx;
 303     BIO *next;
 304     int pend;
 305
 306     ctx = BIO_get_data(b);
 307     next = BIO_next(b);
 308     if (ctx == NULL)
 309         return 0;
 310
 311     switch (cmd) {
 312     case BIO_CTRL_RESET:
 313         ctx->ok = 1;
 314         ctx->finished = 0;
 315         if (!EVP_CipherInit_ex(ctx->cipher, NULL, NULL, NULL, NULL,
 316                                EVP_CIPHER_CTX_is_encrypting(ctx->cipher)))
 317             return 0;
 318         ret = BIO_ctrl(next, cmd, num, ptr);
 319         break;
 320     case BIO_CTRL_EOF:         /* More to read */
 321         if (ctx->cont <= 0)
 322             ret = 1;
 323         else
 324             ret = BIO_ctrl(next, cmd, num, ptr);
 325         break;
 326     case BIO_CTRL_WPENDING:
 327         ret = ctx->buf_len - ctx->buf_off;
 328         if (ret <= 0)
 329             ret = BIO_ctrl(next, cmd, num, ptr);
 330         break;
 331     case BIO_CTRL_PENDING:     /* More to read in buffer */
 332         ret = ctx->buf_len - ctx->buf_off;
 333         if (ret <= 0)
 334             ret = BIO_ctrl(next, cmd, num, ptr);
 335         break;
 336     case BIO_CTRL_FLUSH:
 337         /* do a final write */
 338  again:
 339         while (ctx->buf_len != ctx->buf_off) {
 340             pend = ctx->buf_len - ctx->buf_off;
 341             i = enc_write(b, NULL, 0);
 342             /*
 343              * i should never be > 0 here because we didn't ask to write any
 344              * new data. We stop if we get an error or we failed to make any
 345              * progress writing pending data.
 346              */
 347             if (i < 0 || (ctx->buf_len - ctx->buf_off) == pend)
 348                 return i;
 349         }
 350
 351         if (!ctx->finished) {
 352             ctx->finished = 1;
 353             ctx->buf_off = 0;
 354             ret = EVP_CipherFinal_ex(ctx->cipher,
 355                                      (unsigned char *)ctx->buf,
 356                                      &(ctx->buf_len));
 357             ctx->ok = (int)ret;
 358             if (ret <= 0)
 359                 break;
 360
 361             /* push out the bytes */
 362             goto again;
 363         }
 364
 365         /* Finally flush the underlying BIO */
 366         ret = BIO_ctrl(next, cmd, num, ptr);
 367         BIO_copy_next_retry(b);
 368         break;
 369     case BIO_C_GET_CIPHER_STATUS:
 370         ret = (long)ctx->ok;
 371         break;
 372     case BIO_C_DO_STATE_MACHINE:
 373         BIO_clear_retry_flags(b);
 374         ret = BIO_ctrl(next, cmd, num, ptr);
 375         BIO_copy_next_retry(b);
 376         break;
 377     case BIO_C_GET_CIPHER_CTX:
 378         c_ctx = (EVP_CIPHER_CTX **)ptr;
 379         *c_ctx = ctx->cipher;
 380         BIO_set_init(b, 1);
 381         break;
 382     case BIO_CTRL_DUP:
 383         dbio = (BIO *)ptr;
 384         dctx = BIO_get_data(dbio);
 385         dctx->cipher = EVP_CIPHER_CTX_new();
 386         if (dctx->cipher == NULL)
 387             return 0;
 388         ret = EVP_CIPHER_CTX_copy(dctx->cipher, ctx->cipher);
 389         if (ret)
 390             BIO_set_init(dbio, 1);
 391         break;
 392     default:
 393         ret = BIO_ctrl(next, cmd, num, ptr);
 394         break;
 395     }
 396     return ret;
 397 }
 398
 399 static long enc_callback_ctrl(BIO *b, int cmd, BIO_info_cb *fp)
 400 {
 401     BIO *next = BIO_next(b);
 402
 403     if (next == NULL)
 404         return 0;
 405
 406     return BIO_callback_ctrl(next, cmd, fp);
 407 }
 408
 409 int BIO_set_cipher(BIO *b, const EVP_CIPHER *c, const unsigned char *k,
 410                    const unsigned char *i, int e)
 411 {
 412     BIO_ENC_CTX *ctx;
 413     BIO_callback_fn_ex callback_ex;
 414 #ifndef OPENSSL_NO_DEPRECATED_3_0
 415     long (*callback) (struct bio_st *, int, const char *, int, long, long) = NULL;
 416 #endif
 417
 418     ctx = BIO_get_data(b);
 419     if (ctx == NULL)
 420         return 0;
 421
 422     if ((callback_ex = BIO_get_callback_ex(b)) != NULL) {
 423         if (callback_ex(b, BIO_CB_CTRL, (const char *)c, 0, BIO_CTRL_SET,
 424                         e, 1, NULL) <= 0)
 425             return 0;
 426     }
 427 #ifndef OPENSSL_NO_DEPRECATED_3_0
 428     else {
 429         callback = BIO_get_callback(b);
 430
 431         if ((callback != NULL) &&
 432             (callback(b, BIO_CB_CTRL, (const char *)c, BIO_CTRL_SET, e,
 433                       0L) <= 0))
 434             return 0;
 435     }
 436 #endif
 437
 438     BIO_set_init(b, 1);
 439
 440     if (!EVP_CipherInit_ex(ctx->cipher, c, NULL, k, i, e))
 441         return 0;
 442
 443     if (callback_ex != NULL)
 444         return callback_ex(b, BIO_CB_CTRL | BIO_CB_RETURN, (const char *)c, 0,
 445                            BIO_CTRL_SET, e, 1, NULL);
 446 #ifndef OPENSSL_NO_DEPRECATED_3_0
 447     else if (callback != NULL)
 448         return callback(b, BIO_CB_CTRL, (const char *)c, BIO_CTRL_SET, e, 1L);
 449 #endif
 450     return 1;
 451 }