LCOV - code coverage report
Current view: top level - src/libavformat - crypto.c (source / functions) Hit Total Coverage
Test: coverage.info Lines: 0 181 0.0 %
Date: 2017-01-24 04:42:20 Functions: 0 6 0.0 %

          Line data    Source code
       1             : /*
       2             :  * Decryption protocol handler
       3             :  * Copyright (c) 2011 Martin Storsjo
       4             :  *
       5             :  * This file is part of FFmpeg.
       6             :  *
       7             :  * FFmpeg is free software; you can redistribute it and/or
       8             :  * modify it under the terms of the GNU Lesser General Public
       9             :  * License as published by the Free Software Foundation; either
      10             :  * version 2.1 of the License, or (at your option) any later version.
      11             :  *
      12             :  * FFmpeg is distributed in the hope that it will be useful,
      13             :  * but WITHOUT ANY WARRANTY; without even the implied warranty of
      14             :  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      15             :  * Lesser General Public License for more details.
      16             :  *
      17             :  * You should have received a copy of the GNU Lesser General Public
      18             :  * License along with FFmpeg; if not, write to the Free Software
      19             :  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
      20             :  */
      21             : 
      22             : #include "avformat.h"
      23             : #include "libavutil/aes.h"
      24             : #include "libavutil/avstring.h"
      25             : #include "libavutil/opt.h"
      26             : #include "internal.h"
      27             : #include "url.h"
      28             : 
      29             : // encourage reads of 4096 bytes - 1 block is always retained.
      30             : #define MAX_BUFFER_BLOCKS 257
      31             : #define BLOCKSIZE 16
      32             : 
      33             : typedef struct CryptoContext {
      34             :     const AVClass *class;
      35             :     URLContext *hd;
      36             :     uint8_t inbuffer [BLOCKSIZE*MAX_BUFFER_BLOCKS],
      37             :             outbuffer[BLOCKSIZE*MAX_BUFFER_BLOCKS];
      38             :     uint8_t *outptr;
      39             :     int indata, indata_used, outdata;
      40             :     int64_t position;  // position in file - used in seek
      41             :     int flags;
      42             :     int eof;
      43             :     uint8_t *key;
      44             :     int keylen;
      45             :     uint8_t *iv;
      46             :     int ivlen;
      47             :     uint8_t *decrypt_key;
      48             :     int decrypt_keylen;
      49             :     uint8_t *decrypt_iv;
      50             :     int decrypt_ivlen;
      51             :     uint8_t *encrypt_key;
      52             :     int encrypt_keylen;
      53             :     uint8_t *encrypt_iv;
      54             :     int encrypt_ivlen;
      55             :     struct AVAES *aes_decrypt;
      56             :     struct AVAES *aes_encrypt;
      57             : 
      58             :     uint8_t pad[BLOCKSIZE];
      59             :     int pad_len;
      60             : 
      61             : } CryptoContext;
      62             : 
      63             : #define OFFSET(x) offsetof(CryptoContext, x)
      64             : #define D AV_OPT_FLAG_DECODING_PARAM
      65             : #define E AV_OPT_FLAG_ENCODING_PARAM
      66             : static const AVOption options[] = {
      67             :     {"key", "AES encryption/decryption key",                   OFFSET(key),         AV_OPT_TYPE_BINARY, .flags = D|E },
      68             :     {"iv",  "AES encryption/decryption initialization vector", OFFSET(iv),          AV_OPT_TYPE_BINARY, .flags = D|E },
      69             :     {"decryption_key", "AES decryption key",                   OFFSET(decrypt_key), AV_OPT_TYPE_BINARY, .flags = D },
      70             :     {"decryption_iv",  "AES decryption initialization vector", OFFSET(decrypt_iv),  AV_OPT_TYPE_BINARY, .flags = D },
      71             :     {"encryption_key", "AES encryption key",                   OFFSET(encrypt_key), AV_OPT_TYPE_BINARY, .flags = E },
      72             :     {"encryption_iv",  "AES encryption initialization vector", OFFSET(encrypt_iv),  AV_OPT_TYPE_BINARY, .flags = E },
      73             :     { NULL }
      74             : };
      75             : 
      76             : static const AVClass crypto_class = {
      77             :     .class_name     = "crypto",
      78             :     .item_name      = av_default_item_name,
      79             :     .option         = options,
      80             :     .version        = LIBAVUTIL_VERSION_INT,
      81             : };
      82             : 
      83           0 : static int set_aes_arg(CryptoContext *c, uint8_t **buf, int *buf_len,
      84             :                        uint8_t *default_buf, int default_buf_len,
      85             :                        const char *desc)
      86             : {
      87           0 :     if (!*buf_len) {
      88           0 :         if (!default_buf_len) {
      89           0 :             av_log(c, AV_LOG_ERROR, "%s not set\n", desc);
      90           0 :             return AVERROR(EINVAL);
      91           0 :         } else if (default_buf_len != BLOCKSIZE) {
      92           0 :             av_log(c, AV_LOG_ERROR,
      93             :                    "invalid %s size (%d bytes, block size is %d)\n",
      94             :                    desc, default_buf_len, BLOCKSIZE);
      95           0 :             return AVERROR(EINVAL);
      96             :         }
      97           0 :         *buf = av_memdup(default_buf, default_buf_len);
      98           0 :         if (!*buf)
      99           0 :             return AVERROR(ENOMEM);
     100           0 :         *buf_len = default_buf_len;
     101           0 :     } else if (*buf_len != BLOCKSIZE) {
     102           0 :         av_log(c, AV_LOG_ERROR,
     103             :                "invalid %s size (%d bytes, block size is %d)\n",
     104             :                desc, *buf_len, BLOCKSIZE);
     105           0 :         return AVERROR(EINVAL);
     106             :     }
     107           0 :     return 0;
     108             : }
     109             : 
     110           0 : static int crypto_open2(URLContext *h, const char *uri, int flags, AVDictionary **options)
     111             : {
     112             :     const char *nested_url;
     113           0 :     int ret = 0;
     114           0 :     CryptoContext *c = h->priv_data;
     115           0 :     c->flags = flags;
     116             : 
     117           0 :     if (!av_strstart(uri, "crypto+", &nested_url) &&
     118           0 :         !av_strstart(uri, "crypto:", &nested_url)) {
     119           0 :         av_log(h, AV_LOG_ERROR, "Unsupported url %s\n", uri);
     120           0 :         ret = AVERROR(EINVAL);
     121           0 :         goto err;
     122             :     }
     123             : 
     124           0 :     c->position = 0;
     125             : 
     126           0 :     if (flags & AVIO_FLAG_READ) {
     127           0 :         if ((ret = set_aes_arg(c, &c->decrypt_key, &c->decrypt_keylen,
     128             :                                c->key, c->keylen, "decryption key")) < 0)
     129           0 :             goto err;
     130           0 :         if ((ret = set_aes_arg(c, &c->decrypt_iv, &c->decrypt_ivlen,
     131             :                                c->iv, c->ivlen, "decryption IV")) < 0)
     132           0 :             goto err;
     133             :     }
     134             : 
     135           0 :     if (flags & AVIO_FLAG_WRITE) {
     136           0 :         if ((ret = set_aes_arg(c, &c->encrypt_key, &c->encrypt_keylen,
     137             :                                c->key, c->keylen, "encryption key")) < 0)
     138           0 :         if (ret < 0)
     139           0 :             goto err;
     140           0 :         if ((ret = set_aes_arg(c, &c->encrypt_iv, &c->encrypt_ivlen,
     141             :                                c->iv, c->ivlen, "encryption IV")) < 0)
     142           0 :             goto err;
     143             :     }
     144             : 
     145           0 :     if ((ret = ffurl_open_whitelist(&c->hd, nested_url, flags,
     146           0 :                                     &h->interrupt_callback, options,
     147             :                                     h->protocol_whitelist, h->protocol_blacklist, h)) < 0) {
     148           0 :         av_log(h, AV_LOG_ERROR, "Unable to open resource: %s\n", nested_url);
     149           0 :         goto err;
     150             :     }
     151             : 
     152           0 :     if (flags & AVIO_FLAG_READ) {
     153           0 :         c->aes_decrypt = av_aes_alloc();
     154           0 :         if (!c->aes_decrypt) {
     155           0 :             ret = AVERROR(ENOMEM);
     156           0 :             goto err;
     157             :         }
     158           0 :         ret = av_aes_init(c->aes_decrypt, c->decrypt_key, BLOCKSIZE*8, 1);
     159           0 :         if (ret < 0)
     160           0 :             goto err;
     161             : 
     162             :         // pass back information about the context we openned
     163           0 :         if (c->hd->is_streamed)
     164           0 :             h->is_streamed = c->hd->is_streamed;
     165             :     }
     166             : 
     167           0 :     if (flags & AVIO_FLAG_WRITE) {
     168           0 :         c->aes_encrypt = av_aes_alloc();
     169           0 :         if (!c->aes_encrypt) {
     170           0 :             ret = AVERROR(ENOMEM);
     171           0 :             goto err;
     172             :         }
     173           0 :         ret = av_aes_init(c->aes_encrypt, c->encrypt_key, BLOCKSIZE*8, 0);
     174           0 :         if (ret < 0)
     175           0 :             goto err;
     176             :         // for write, we must be streamed
     177             :         // - linear write only for crytpo aes-128-cbc
     178           0 :         h->is_streamed = 1;
     179             :     }
     180             : 
     181           0 :     c->pad_len = 0;
     182             : 
     183             : err:
     184           0 :     return ret;
     185             : }
     186             : 
     187           0 : static int crypto_read(URLContext *h, uint8_t *buf, int size)
     188             : {
     189           0 :     CryptoContext *c = h->priv_data;
     190             :     int blocks;
     191             : retry:
     192           0 :     if (c->outdata > 0) {
     193           0 :         size = FFMIN(size, c->outdata);
     194           0 :         memcpy(buf, c->outptr, size);
     195           0 :         c->outptr  += size;
     196           0 :         c->outdata -= size;
     197           0 :         c->position = c->position + size;
     198           0 :         return size;
     199             :     }
     200             :     // We avoid using the last block until we've found EOF,
     201             :     // since we'll remove PKCS7 padding at the end. So make
     202             :     // sure we've got at least 2 blocks, so we can decrypt
     203             :     // at least one.
     204           0 :     while (c->indata - c->indata_used < 2*BLOCKSIZE) {
     205           0 :         int n = ffurl_read(c->hd, c->inbuffer + c->indata,
     206           0 :                            sizeof(c->inbuffer) - c->indata);
     207           0 :         if (n <= 0) {
     208           0 :             c->eof = 1;
     209           0 :             break;
     210             :         }
     211           0 :         c->indata += n;
     212             :     }
     213           0 :     blocks = (c->indata - c->indata_used) / BLOCKSIZE;
     214           0 :     if (!blocks)
     215           0 :         return AVERROR_EOF;
     216           0 :     if (!c->eof)
     217           0 :         blocks--;
     218           0 :     av_aes_crypt(c->aes_decrypt, c->outbuffer, c->inbuffer + c->indata_used,
     219             :                  blocks, c->decrypt_iv, 1);
     220           0 :     c->outdata      = BLOCKSIZE * blocks;
     221           0 :     c->outptr       = c->outbuffer;
     222           0 :     c->indata_used += BLOCKSIZE * blocks;
     223           0 :     if (c->indata_used >= sizeof(c->inbuffer)/2) {
     224           0 :         memmove(c->inbuffer, c->inbuffer + c->indata_used,
     225           0 :                 c->indata - c->indata_used);
     226           0 :         c->indata     -= c->indata_used;
     227           0 :         c->indata_used = 0;
     228             :     }
     229           0 :     if (c->eof) {
     230             :         // Remove PKCS7 padding at the end
     231           0 :         int padding = c->outbuffer[c->outdata - 1];
     232           0 :         c->outdata -= padding;
     233             :     }
     234           0 :     goto retry;
     235             : }
     236             : 
     237           0 : static int64_t crypto_seek(URLContext *h, int64_t pos, int whence)
     238             : {
     239           0 :     CryptoContext *c = h->priv_data;
     240             :     int64_t block;
     241             :     int64_t newpos;
     242             : 
     243           0 :     if (c->flags & AVIO_FLAG_WRITE) {
     244           0 :         av_log(h, AV_LOG_ERROR,
     245             :             "Crypto: seek not supported for write\r\n");
     246             :         /* seems the most appropriate error to return */
     247           0 :         return AVERROR(ESPIPE);
     248             :     }
     249             : 
     250             :     // reset eof, else we won't read it correctly if we already hit eof.
     251           0 :     c->eof = 0;
     252             : 
     253           0 :     switch (whence) {
     254             :     case SEEK_SET:
     255           0 :         break;
     256             :     case SEEK_CUR:
     257           0 :         pos = pos + c->position;
     258           0 :         break;
     259             :     case SEEK_END: {
     260           0 :         int64_t newpos = ffurl_seek( c->hd, pos, AVSEEK_SIZE );
     261           0 :         if (newpos < 0) {
     262           0 :             av_log(h, AV_LOG_ERROR,
     263             :                 "Crypto: seek_end - can't get file size (pos=%lld)\r\n", (long long int)pos);
     264           0 :             return newpos;
     265             :         }
     266           0 :         pos = newpos - pos;
     267             :         }
     268           0 :         break;
     269             :     case AVSEEK_SIZE: {
     270           0 :         int64_t newpos = ffurl_seek( c->hd, pos, AVSEEK_SIZE );
     271           0 :         return newpos;
     272             :         }
     273             :         break;
     274             :     default:
     275           0 :         av_log(h, AV_LOG_ERROR,
     276             :             "Crypto: no support for seek where 'whence' is %d\r\n", whence);
     277           0 :         return AVERROR(EINVAL);
     278             :     }
     279             : 
     280           0 :     c->outdata = 0;
     281           0 :     c->indata = 0;
     282           0 :     c->indata_used = 0;
     283           0 :     c->outptr = c->outbuffer;
     284             : 
     285             :     // identify the block containing the IV for the
     286             :     // next block we will decrypt
     287           0 :     block = pos/BLOCKSIZE;
     288           0 :     if (block == 0) {
     289             :         // restore the iv to the seed one - this is the iv for the FIRST block
     290           0 :         memcpy( c->decrypt_iv, c->iv, c->ivlen );
     291           0 :         c->position = 0;
     292             :     } else {
     293             :         // else, go back one block - we will get av_cyrpt to read this block
     294             :         // which it will then store use as the iv.
     295             :         // note that the DECRYPTED result will not be correct,
     296             :         // but will be discarded
     297           0 :         block--;
     298           0 :         c->position = (block * BLOCKSIZE);
     299             :     }
     300             : 
     301           0 :     newpos = ffurl_seek( c->hd, c->position, SEEK_SET );
     302           0 :     if (newpos < 0) {
     303           0 :         av_log(h, AV_LOG_ERROR,
     304             :             "Crypto: nested protocol no support for seek or seek failed\n");
     305           0 :         return newpos;
     306             :     }
     307             : 
     308             :     // read and discard from here up to required position
     309             :     // (which will set the iv correctly to it).
     310           0 :     if (pos - c->position) {
     311             :         uint8_t buff[BLOCKSIZE*2]; // maximum size of pos-c->position
     312           0 :         int len = pos - c->position;
     313             :         int res;
     314             : 
     315           0 :         while (len > 0) {
     316             :             // note: this may not return all the bytes first time
     317           0 :             res = crypto_read(h, buff, len);
     318           0 :             if (res < 0)
     319           0 :                 break;
     320           0 :             len -= res;
     321             :         }
     322             : 
     323             :         // if we did not get all the bytes
     324           0 :         if (len != 0) {
     325           0 :             char errbuf[100] = "unknown error";
     326           0 :             av_strerror(res, errbuf, sizeof(errbuf));
     327           0 :             av_log(h, AV_LOG_ERROR,
     328             :                 "Crypto: discard read did not get all the bytes (%d remain) - read returned (%d)-%s\n",
     329             :                 len, res, errbuf);
     330           0 :             return AVERROR(EINVAL);
     331             :         }
     332             :     }
     333             : 
     334           0 :     return c->position;
     335             : }
     336             : 
     337           0 : static int crypto_write(URLContext *h, const unsigned char *buf, int size)
     338             : {
     339           0 :     CryptoContext *c = h->priv_data;
     340             :     int total_size, blocks, pad_len, out_size;
     341             :     uint8_t *out_buf;
     342           0 :     int ret = 0;
     343             : 
     344           0 :     total_size = size + c->pad_len;
     345           0 :     pad_len = total_size % BLOCKSIZE;
     346           0 :     out_size = total_size - pad_len;
     347           0 :     blocks = out_size / BLOCKSIZE;
     348             : 
     349           0 :     if (out_size) {
     350           0 :         out_buf = av_malloc(out_size);
     351           0 :         if (!out_buf)
     352           0 :             return AVERROR(ENOMEM);
     353             : 
     354           0 :         if (c->pad_len) {
     355           0 :             memcpy(&c->pad[c->pad_len], buf, BLOCKSIZE - c->pad_len);
     356           0 :             av_aes_crypt(c->aes_encrypt, out_buf, c->pad, 1, c->encrypt_iv, 0);
     357           0 :             blocks--;
     358             :         }
     359             : 
     360           0 :         av_aes_crypt(c->aes_encrypt, &out_buf[c->pad_len ? BLOCKSIZE : 0],
     361           0 :                              &buf[c->pad_len ? BLOCKSIZE - c->pad_len: 0],
     362             :                              blocks, c->encrypt_iv, 0);
     363             : 
     364           0 :         ret = ffurl_write(c->hd, out_buf, out_size);
     365           0 :         av_free(out_buf);
     366           0 :         if (ret < 0)
     367           0 :             return ret;
     368             : 
     369           0 :         memcpy(c->pad, &buf[size - pad_len], pad_len);
     370             :     } else
     371           0 :         memcpy(&c->pad[c->pad_len], buf, size);
     372             : 
     373           0 :     c->pad_len = pad_len;
     374             : 
     375           0 :     return size;
     376             : }
     377             : 
     378           0 : static int crypto_close(URLContext *h)
     379             : {
     380           0 :     CryptoContext *c = h->priv_data;
     381             :     uint8_t out_buf[BLOCKSIZE];
     382             :     int ret, pad;
     383             : 
     384           0 :     if (c->aes_encrypt) {
     385           0 :         pad = BLOCKSIZE - c->pad_len;
     386           0 :         memset(&c->pad[c->pad_len], pad, pad);
     387           0 :         av_aes_crypt(c->aes_encrypt, out_buf, c->pad, 1, c->encrypt_iv, 0);
     388           0 :         if ((ret =  ffurl_write(c->hd, out_buf, BLOCKSIZE)) < 0)
     389           0 :             return ret;
     390             :     }
     391             : 
     392           0 :     if (c->hd)
     393           0 :         ffurl_close(c->hd);
     394           0 :     av_freep(&c->aes_decrypt);
     395           0 :     av_freep(&c->aes_encrypt);
     396           0 :     return 0;
     397             : }
     398             : 
     399             : const URLProtocol ff_crypto_protocol = {
     400             :     .name            = "crypto",
     401             :     .url_open2       = crypto_open2,
     402             :     .url_seek        = crypto_seek,
     403             :     .url_read        = crypto_read,
     404             :     .url_write       = crypto_write,
     405             :     .url_close       = crypto_close,
     406             :     .priv_data_size  = sizeof(CryptoContext),
     407             :     .priv_data_class = &crypto_class,
     408             :     .flags           = URL_PROTOCOL_FLAG_NESTED_SCHEME,
     409             : };

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