crypto/evp/bio_enc.c

   1 /*
   2  * Copyright 1995-2021 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     if (blocksize == 1)
 136         blocksize = 0;
 137
 138     /*
 139      * At this point, we have room of outl bytes and an empty buffer, so we
 140      * should read in some more.
 141      */
 142
 143     while (outl > 0) {
 144         if (ctx->cont <= 0)
 145             break;
 146
 147         if (ctx->read_start == ctx->read_end) { /* time to read more data */
 148             ctx->read_end = ctx->read_start = &(ctx->buf[BUF_OFFSET]);
 149             i = BIO_read(next, ctx->read_start, ENC_BLOCK_SIZE);
 150             if (i > 0)
 151                 ctx->read_end += i;
 152         } else {
 153             i = ctx->read_end - ctx->read_start;
 154         }
 155
 156         if (i <= 0) {
 157             /* Should be continue next time we are called? */
 158             if (!BIO_should_retry(next)) {
 159                 ctx->cont = i;
 160                 i = EVP_CipherFinal_ex(ctx->cipher,
 161                                        ctx->buf, &(ctx->buf_len));
 162                 ctx->ok = i;
 163                 ctx->buf_off = 0;
 164             } else {
 165                 ret = (ret == 0) ? i : ret;
 166                 break;
 167             }
 168         } else {
 169             if (outl > ENC_MIN_CHUNK) {
 170                 /*
 171                  * Depending on flags block cipher decrypt can write
 172                  * one extra block and then back off, i.e. output buffer
 173                  * has to accommodate extra block...
 174                  */
 175                 int j = outl - blocksize, buf_len;
 176
 177                 if (!EVP_CipherUpdate(ctx->cipher,
 178                                       (unsigned char *)out, &buf_len,
 179                                       ctx->read_start, i > j ? j : i)) {
 180                     BIO_clear_retry_flags(b);
 181                     return 0;
 182                 }
 183                 ret += buf_len;
 184                 out += buf_len;
 185                 outl -= buf_len;
 186
 187                 if ((i -= j) <= 0) {
 188                     ctx->read_start = ctx->read_end;
 189                     continue;
 190                 }
 191                 ctx->read_start += j;
 192             }
 193             if (i > ENC_MIN_CHUNK)
 194                 i = ENC_MIN_CHUNK;
 195             if (!EVP_CipherUpdate(ctx->cipher,
 196                                   ctx->buf, &ctx->buf_len,
 197                                   ctx->read_start, i)) {
 198                 BIO_clear_retry_flags(b);
 199                 ctx->ok = 0;
 200                 return 0;
 201             }
 202             ctx->read_start += i;
 203             ctx->cont = 1;
 204             /*
 205              * Note: it is possible for EVP_CipherUpdate to decrypt zero
 206              * bytes because this is or looks like the final block: if this
 207              * happens we should retry and either read more data or decrypt
 208              * the final block
 209              */
 210             if (ctx->buf_len == 0)
 211                 continue;
 212         }
 213
 214         if (ctx->buf_len <= outl)
 215             i = ctx->buf_len;
 216         else
 217             i = outl;
 218         if (i <= 0)
 219             break;
 220         memcpy(out, ctx->buf, i);
 221         ret += i;
 222         ctx->buf_off = i;
 223         outl -= i;
 224         out += i;
 225     }
 226
 227     BIO_clear_retry_flags(b);
 228     BIO_copy_next_retry(b);
 229     return ((ret == 0) ? ctx->cont : ret);
 230 }
 231
 232 static int enc_write(BIO *b, const char *in, int inl)
 233 {
 234     int ret = 0, n, i;
 235     BIO_ENC_CTX *ctx;
 236     BIO *next;
 237
 238     ctx = BIO_get_data(b);
 239     next = BIO_next(b);
 240     if ((ctx == NULL) || (next == NULL))
 241         return 0;
 242
 243     ret = inl;
 244
 245     BIO_clear_retry_flags(b);
 246     n = ctx->buf_len - ctx->buf_off;
 247     while (n > 0) {
 248         i = BIO_write(next, &(ctx->buf[ctx->buf_off]), n);
 249         if (i <= 0) {
 250             BIO_copy_next_retry(b);
 251             return i;
 252         }
 253         ctx->buf_off += i;
 254         n -= i;
 255     }
 256     /* at this point all pending data has been written */
 257
 258     if ((in == NULL) || (inl <= 0))
 259         return 0;
 260
 261     ctx->buf_off = 0;
 262     while (inl > 0) {
 263         n = (inl > ENC_BLOCK_SIZE) ? ENC_BLOCK_SIZE : inl;
 264         if (!EVP_CipherUpdate(ctx->cipher,
 265                               ctx->buf, &ctx->buf_len,
 266                               (const unsigned char *)in, n)) {
 267             BIO_clear_retry_flags(b);
 268             ctx->ok = 0;
 269             return 0;
 270         }
 271         inl -= n;
 272         in += n;
 273
 274         ctx->buf_off = 0;
 275         n = ctx->buf_len;
 276         while (n > 0) {
 277             i = BIO_write(next, &(ctx->buf[ctx->buf_off]), n);
 278             if (i <= 0) {
 279                 BIO_copy_next_retry(b);
 280                 return (ret == inl) ? i : ret - inl;
 281             }
 282             n -= i;
 283             ctx->buf_off += i;
 284         }
 285         ctx->buf_len = 0;
 286         ctx->buf_off = 0;
 287     }
 288     BIO_copy_next_retry(b);
 289     return ret;
 290 }
 291
 292 static long enc_ctrl(BIO *b, int cmd, long num, void *ptr)
 293 {
 294     BIO *dbio;
 295     BIO_ENC_CTX *ctx, *dctx;
 296     long ret = 1;
 297     int i;
 298     EVP_CIPHER_CTX **c_ctx;
 299     BIO *next;
 300
 301     ctx = BIO_get_data(b);
 302     next = BIO_next(b);
 303     if (ctx == NULL)
 304         return 0;
 305
 306     switch (cmd) {
 307     case BIO_CTRL_RESET:
 308         ctx->ok = 1;
 309         ctx->finished = 0;
 310         if (!EVP_CipherInit_ex(ctx->cipher, NULL, NULL, NULL, NULL,
 311                                EVP_CIPHER_CTX_is_encrypting(ctx->cipher)))
 312             return 0;
 313         ret = BIO_ctrl(next, cmd, num, ptr);
 314         break;
 315     case BIO_CTRL_EOF:         /* More to read */
 316         if (ctx->cont <= 0)
 317             ret = 1;
 318         else
 319             ret = BIO_ctrl(next, cmd, num, ptr);
 320         break;
 321     case BIO_CTRL_WPENDING:
 322         ret = ctx->buf_len - ctx->buf_off;
 323         if (ret <= 0)
 324             ret = BIO_ctrl(next, cmd, num, ptr);
 325         break;
 326     case BIO_CTRL_PENDING:     /* More to read in buffer */
 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_FLUSH:
 332         /* do a final write */
 333  again:
 334         while (ctx->buf_len != ctx->buf_off) {
 335             i = enc_write(b, NULL, 0);
 336             if (i < 0)
 337                 return i;
 338         }
 339
 340         if (!ctx->finished) {
 341             ctx->finished = 1;
 342             ctx->buf_off = 0;
 343             ret = EVP_CipherFinal_ex(ctx->cipher,
 344                                      (unsigned char *)ctx->buf,
 345                                      &(ctx->buf_len));
 346             ctx->ok = (int)ret;
 347             if (ret <= 0)
 348                 break;
 349
 350             /* push out the bytes */
 351             goto again;
 352         }
 353
 354         /* Finally flush the underlying BIO */
 355         ret = BIO_ctrl(next, cmd, num, ptr);
 356         break;
 357     case BIO_C_GET_CIPHER_STATUS:
 358         ret = (long)ctx->ok;
 359         break;
 360     case BIO_C_DO_STATE_MACHINE:
 361         BIO_clear_retry_flags(b);
 362         ret = BIO_ctrl(next, cmd, num, ptr);
 363         BIO_copy_next_retry(b);
 364         break;
 365     case BIO_C_GET_CIPHER_CTX:
 366         c_ctx = (EVP_CIPHER_CTX **)ptr;
 367         *c_ctx = ctx->cipher;
 368         BIO_set_init(b, 1);
 369         break;
 370     case BIO_CTRL_DUP:
 371         dbio = (BIO *)ptr;
 372         dctx = BIO_get_data(dbio);
 373         dctx->cipher = EVP_CIPHER_CTX_new();
 374         if (dctx->cipher == NULL)
 375             return 0;
 376         ret = EVP_CIPHER_CTX_copy(dctx->cipher, ctx->cipher);
 377         if (ret)
 378             BIO_set_init(dbio, 1);
 379         break;
 380     default:
 381         ret = BIO_ctrl(next, cmd, num, ptr);
 382         break;
 383     }
 384     return ret;
 385 }
 386
 387 static long enc_callback_ctrl(BIO *b, int cmd, BIO_info_cb *fp)
 388 {
 389     BIO *next = BIO_next(b);
 390
 391     if (next == NULL)
 392         return 0;
 393
 394     return BIO_callback_ctrl(next, cmd, fp);
 395 }
 396
 397 int BIO_set_cipher(BIO *b, const EVP_CIPHER *c, const unsigned char *k,
 398                    const unsigned char *i, int e)
 399 {
 400     BIO_ENC_CTX *ctx;
 401     BIO_callback_fn_ex callback_ex;
 402 #ifndef OPENSSL_NO_DEPRECATED_3_0
 403     long (*callback) (struct bio_st *, int, const char *, int, long, long) = NULL;
 404 #endif
 405
 406     ctx = BIO_get_data(b);
 407     if (ctx == NULL)
 408         return 0;
 409
 410     if ((callback_ex = BIO_get_callback_ex(b)) != NULL) {
 411         if (callback_ex(b, BIO_CB_CTRL, (const char *)c, 0, BIO_CTRL_SET,
 412                         e, 1, NULL) <= 0)
 413             return 0;
 414     }
 415 #ifndef OPENSSL_NO_DEPRECATED_3_0
 416     else {
 417         callback = BIO_get_callback(b);
 418
 419         if ((callback != NULL) &&
 420             (callback(b, BIO_CB_CTRL, (const char *)c, BIO_CTRL_SET, e,
 421                       0L) <= 0))
 422             return 0;
 423     }
 424 #endif
 425
 426     BIO_set_init(b, 1);
 427
 428     if (!EVP_CipherInit_ex(ctx->cipher, c, NULL, k, i, e))
 429         return 0;
 430
 431     if (callback_ex != NULL)
 432         return callback_ex(b, BIO_CB_CTRL | BIO_CB_RETURN, (const char *)c, 0,
 433                            BIO_CTRL_SET, e, 1, NULL);
 434 #ifndef OPENSSL_NO_DEPRECATED_3_0
 435     else if (callback != NULL)
 436         return callback(b, BIO_CB_CTRL, (const char *)c, BIO_CTRL_SET, e, 1L);
 437 #endif
 438     return 1;
 439 }