FFmpeg coverage

Line	Branch	Exec	Source
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 <inttypes.h>
23			#include <string.h>
24
25			#include "libavutil/aes.h"
26			#include "libavutil/avstring.h"
27			#include "libavutil/error.h"
28			#include "libavutil/mem.h"
29			#include "libavutil/opt.h"
30			#include "url.h"
31
32			// encourage reads of 4096 bytes - 1 block is always retained.
33			#define MAX_BUFFER_BLOCKS 257
34			#define BLOCKSIZE 16
35
36			typedef struct CryptoContext {
37			const AVClass *class;
38			URLContext *hd;
39			uint8_t inbuffer [BLOCKSIZE*MAX_BUFFER_BLOCKS],
40			outbuffer[BLOCKSIZE*MAX_BUFFER_BLOCKS];
41			uint8_t *outptr;
42			int indata, indata_used, outdata;
43			int64_t position; // position in file - used in seek
44			int flags;
45			int eof;
46			uint8_t *key;
47			int keylen;
48			uint8_t *iv;
49			int ivlen;
50			uint8_t *decrypt_key;
51			int decrypt_keylen;
52			uint8_t *decrypt_iv;
53			int decrypt_ivlen;
54			uint8_t *encrypt_key;
55			int encrypt_keylen;
56			uint8_t *encrypt_iv;
57			int encrypt_ivlen;
58			struct AVAES *aes_decrypt;
59			struct AVAES *aes_encrypt;
60			uint8_t *write_buf;
61			unsigned int write_buf_size;
62			uint8_t pad[BLOCKSIZE];
63			int pad_len;
64			} CryptoContext;
65
66			#define OFFSET(x) offsetof(CryptoContext, x)
67			#define D AV_OPT_FLAG_DECODING_PARAM
68			#define E AV_OPT_FLAG_ENCODING_PARAM
69			static const AVOption crypto_options[] = {
70			{"key", "AES encryption/decryption key", OFFSET(key), AV_OPT_TYPE_BINARY, .flags = D|E },
71			{"iv", "AES encryption/decryption initialization vector", OFFSET(iv), AV_OPT_TYPE_BINARY, .flags = D|E },
72			{"decryption_key", "AES decryption key", OFFSET(decrypt_key), AV_OPT_TYPE_BINARY, .flags = D },
73			{"decryption_iv", "AES decryption initialization vector", OFFSET(decrypt_iv), AV_OPT_TYPE_BINARY, .flags = D },
74			{"encryption_key", "AES encryption key", OFFSET(encrypt_key), AV_OPT_TYPE_BINARY, .flags = E },
75			{"encryption_iv", "AES encryption initialization vector", OFFSET(encrypt_iv), AV_OPT_TYPE_BINARY, .flags = E },
76			{ NULL }
77			};
78
79			static const AVClass crypto_class = {
80			.class_name = "crypto",
81			.item_name = av_default_item_name,
82			.option = crypto_options,
83			.version = LIBAVUTIL_VERSION_INT,
84			};
85
86		✗	static int set_aes_arg(URLContext *h, uint8_t **buf, int *buf_len,
87			uint8_t *default_buf, int default_buf_len,
88			const char *desc)
89			{
90		✗	if (!*buf_len) {
91		✗	if (!default_buf_len) {
92		✗	av_log(h, AV_LOG_ERROR, "%s not set\n", desc);
93		✗	return AVERROR(EINVAL);
94		✗	} else if (default_buf_len != BLOCKSIZE) {
95		✗	av_log(h, AV_LOG_ERROR,
96			"invalid %s size (%d bytes, block size is %d)\n",
97			desc, default_buf_len, BLOCKSIZE);
98		✗	return AVERROR(EINVAL);
99			}
100		✗	*buf = av_memdup(default_buf, default_buf_len);
101		✗	if (!*buf)
102		✗	return AVERROR(ENOMEM);
103		✗	*buf_len = default_buf_len;
104		✗	} else if (*buf_len != BLOCKSIZE) {
105		✗	av_log(h, AV_LOG_ERROR,
106			"invalid %s size (%d bytes, block size is %d)\n",
107			desc, *buf_len, BLOCKSIZE);
108		✗	return AVERROR(EINVAL);
109			}
110		✗	return 0;
111			}
112
113		✗	static int crypto_open2(URLContext *h, const char *uri, int flags, AVDictionary **options)
114			{
115			const char *nested_url;
116		✗	int ret = 0;
117		✗	CryptoContext *c = h->priv_data;
118		✗	c->flags = flags;
119
120		✗	if (!av_strstart(uri, "crypto+", &nested_url) &&
121		✗	!av_strstart(uri, "crypto:", &nested_url)) {
122		✗	av_log(h, AV_LOG_ERROR, "Unsupported url %s\n", uri);
123		✗	ret = AVERROR(EINVAL);
124		✗	goto err;
125			}
126
127		✗	if (flags & AVIO_FLAG_READ) {
128		✗	if ((ret = set_aes_arg(h, &c->decrypt_key, &c->decrypt_keylen,
129			c->key, c->keylen, "decryption key")) < 0)
130		✗	goto err;
131		✗	if ((ret = set_aes_arg(h, &c->decrypt_iv, &c->decrypt_ivlen,
132			c->iv, c->ivlen, "decryption IV")) < 0)
133		✗	goto err;
134			}
135
136		✗	if (flags & AVIO_FLAG_WRITE) {
137		✗	if ((ret = set_aes_arg(h, &c->encrypt_key, &c->encrypt_keylen,
138			c->key, c->keylen, "encryption key")) < 0)
139		✗	if (ret < 0)
140		✗	goto err;
141		✗	if ((ret = set_aes_arg(h, &c->encrypt_iv, &c->encrypt_ivlen,
142			c->iv, c->ivlen, "encryption IV")) < 0)
143		✗	goto err;
144			}
145
146		✗	if ((ret = ffurl_open_whitelist(&c->hd, nested_url, flags,
147		✗	&h->interrupt_callback, options,
148			h->protocol_whitelist, h->protocol_blacklist, h)) < 0) {
149		✗	av_log(h, AV_LOG_ERROR, "Unable to open resource: %s\n", nested_url);
150		✗	goto err;
151			}
152
153		✗	if (flags & AVIO_FLAG_READ) {
154		✗	c->aes_decrypt = av_aes_alloc();
155		✗	if (!c->aes_decrypt) {
156		✗	ret = AVERROR(ENOMEM);
157		✗	goto err;
158			}
159		✗	ret = av_aes_init(c->aes_decrypt, c->decrypt_key, BLOCKSIZE * 8, 1);
160		✗	if (ret < 0)
161		✗	goto err;
162
163			// pass back information about the context we opened
164		✗	if (c->hd->is_streamed)
165		✗	h->is_streamed = c->hd->is_streamed;
166			}
167
168		✗	if (flags & AVIO_FLAG_WRITE) {
169		✗	c->aes_encrypt = av_aes_alloc();
170		✗	if (!c->aes_encrypt) {
171		✗	ret = AVERROR(ENOMEM);
172		✗	goto err;
173			}
174		✗	ret = av_aes_init(c->aes_encrypt, c->encrypt_key, BLOCKSIZE * 8, 0);
175		✗	if (ret < 0)
176		✗	goto err;
177			// for write, we must be streamed
178			// - linear write only for crypto aes-128-cbc
179		✗	h->is_streamed = 1;
180			}
181
182		✗	err:
183		✗	return ret;
184			}
185
186		✗	static int crypto_read(URLContext *h, uint8_t *buf, int size)
187			{
188		✗	CryptoContext *c = h->priv_data;
189			int blocks;
190		✗	retry:
191		✗	if (c->outdata > 0) {
192		✗	size = FFMIN(size, c->outdata);
193		✗	memcpy(buf, c->outptr, size);
194		✗	c->outptr += size;
195		✗	c->outdata -= size;
196		✗	c->position = c->position + size;
197		✗	return size;
198			}
199			// We avoid using the last block until we've found EOF,
200			// since we'll remove PKCS7 padding at the end. So make
201			// sure we've got at least 2 blocks, so we can decrypt
202			// at least one.
203		✗	while (c->indata - c->indata_used < 2*BLOCKSIZE) {
204		✗	int n = ffurl_read(c->hd, c->inbuffer + c->indata,
205		✗	sizeof(c->inbuffer) - c->indata);
206		✗	if (n <= 0) {
207		✗	c->eof = 1;
208		✗	break;
209			}
210		✗	c->indata += n;
211			}
212		✗	blocks = (c->indata - c->indata_used) / BLOCKSIZE;
213		✗	if (!blocks)
214		✗	return AVERROR_EOF;
215		✗	if (!c->eof)
216		✗	blocks--;
217		✗	av_aes_crypt(c->aes_decrypt, c->outbuffer, c->inbuffer + c->indata_used,
218			blocks, c->decrypt_iv, 1);
219		✗	c->outdata = BLOCKSIZE * blocks;
220		✗	c->outptr = c->outbuffer;
221		✗	c->indata_used += BLOCKSIZE * blocks;
222		✗	if (c->indata_used >= sizeof(c->inbuffer)/2) {
223		✗	memmove(c->inbuffer, c->inbuffer + c->indata_used,
224		✗	c->indata - c->indata_used);
225		✗	c->indata -= c->indata_used;
226		✗	c->indata_used = 0;
227			}
228		✗	if (c->eof) {
229			// Remove PKCS7 padding at the end
230		✗	int padding = c->outbuffer[c->outdata - 1];
231		✗	c->outdata -= padding;
232			}
233		✗	goto retry;
234			}
235
236		✗	static int64_t crypto_seek(URLContext *h, int64_t pos, int whence)
237			{
238		✗	CryptoContext *c = h->priv_data;
239			int64_t block;
240			int64_t newpos;
241
242		✗	if (c->flags & AVIO_FLAG_WRITE) {
243		✗	av_log(h, AV_LOG_ERROR,
244			"Crypto: seek not supported for write\r\n");
245			/* seems the most appropriate error to return */
246		✗	return AVERROR(ESPIPE);
247			}
248
249			// reset eof, else we won't read it correctly if we already hit eof.
250		✗	c->eof = 0;
251
252		✗	switch (whence) {
253		✗	case SEEK_SET:
254		✗	break;
255		✗	case SEEK_CUR:
256		✗	pos = pos + c->position;
257		✗	break;
258		✗	case SEEK_END:
259		✗	newpos = ffurl_seek( c->hd, pos, AVSEEK_SIZE );
260		✗	if (newpos < 0) {
261		✗	av_log(h, AV_LOG_ERROR,
262			"Crypto: seek_end - can't get file size (pos=%"PRId64")\r\n", pos);
263		✗	return newpos;
264			}
265		✗	pos = newpos - pos;
266		✗	break;
267		✗	case AVSEEK_SIZE:
268		✗	return ffurl_seek( c->hd, pos, AVSEEK_SIZE );
269		✗	default:
270		✗	av_log(h, AV_LOG_ERROR,
271			"Crypto: no support for seek where 'whence' is %d\r\n", whence);
272		✗	return AVERROR(EINVAL);
273			}
274
275		✗	c->outdata = 0;
276		✗	c->indata = 0;
277		✗	c->indata_used = 0;
278		✗	c->outptr = c->outbuffer;
279
280			// identify the block containing the IV for the
281			// next block we will decrypt
282		✗	block = pos/BLOCKSIZE;
283		✗	if (block == 0) {
284			// restore the iv to the seed one - this is the iv for the FIRST block
285		✗	memcpy( c->decrypt_iv, c->iv, c->ivlen );
286		✗	c->position = 0;
287			} else {
288			// else, go back one block - we will get av_cyrpt to read this block
289			// which it will then store use as the iv.
290			// note that the DECRYPTED result will not be correct,
291			// but will be discarded
292		✗	block--;
293		✗	c->position = (block * BLOCKSIZE);
294			}
295
296		✗	newpos = ffurl_seek( c->hd, c->position, SEEK_SET );
297		✗	if (newpos < 0) {
298		✗	av_log(h, AV_LOG_ERROR,
299			"Crypto: nested protocol no support for seek or seek failed\n");
300		✗	return newpos;
301			}
302
303			// read and discard from here up to required position
304			// (which will set the iv correctly to it).
305		✗	if (pos - c->position) {
306			uint8_t buff[BLOCKSIZE*2]; // maximum size of pos-c->position
307		✗	int len = pos - c->position;
308			int res;
309
310		✗	while (len > 0) {
311			// note: this may not return all the bytes first time
312		✗	res = crypto_read(h, buff, len);
313		✗	if (res < 0)
314		✗	break;
315		✗	len -= res;
316			}
317
318			// if we did not get all the bytes
319		✗	if (len != 0) {
320		✗	av_log(h, AV_LOG_ERROR,
321			"Crypto: discard read did not get all the bytes (%d remain) - read returned (%d)-%s\n",
322		✗	len, res, av_err2str(res));
323		✗	return AVERROR(EINVAL);
324			}
325			}
326
327		✗	return c->position;
328			}
329
330		✗	static int crypto_write(URLContext *h, const unsigned char *buf, int size)
331			{
332		✗	CryptoContext *c = h->priv_data;
333			int total_size, blocks, pad_len, out_size;
334		✗	int ret = 0;
335
336		✗	total_size = size + c->pad_len;
337		✗	pad_len = total_size % BLOCKSIZE;
338		✗	out_size = total_size - pad_len;
339		✗	blocks = out_size / BLOCKSIZE;
340
341		✗	if (out_size) {
342		✗	av_fast_malloc(&c->write_buf, &c->write_buf_size, out_size);
343
344		✗	if (!c->write_buf)
345		✗	return AVERROR(ENOMEM);
346
347		✗	if (c->pad_len) {
348		✗	memcpy(&c->pad[c->pad_len], buf, BLOCKSIZE - c->pad_len);
349		✗	av_aes_crypt(c->aes_encrypt, c->write_buf, c->pad, 1, c->encrypt_iv, 0);
350		✗	blocks--;
351			}
352
353		✗	av_aes_crypt(c->aes_encrypt,
354		✗	&c->write_buf[c->pad_len ? BLOCKSIZE : 0],
355		✗	&buf[c->pad_len ? BLOCKSIZE - c->pad_len : 0],
356			blocks, c->encrypt_iv, 0);
357
358		✗	ret = ffurl_write(c->hd, c->write_buf, out_size);
359		✗	if (ret < 0)
360		✗	return ret;
361
362		✗	memcpy(c->pad, &buf[size - pad_len], pad_len);
363			} else
364		✗	memcpy(&c->pad[c->pad_len], buf, size);
365
366		✗	c->pad_len = pad_len;
367
368		✗	return size;
369			}
370
371		✗	static int crypto_close(URLContext *h)
372			{
373		✗	CryptoContext *c = h->priv_data;
374		✗	int ret = 0;
375
376		✗	if (c->aes_encrypt) {
377			uint8_t out_buf[BLOCKSIZE];
378		✗	int pad = BLOCKSIZE - c->pad_len;
379
380		✗	memset(&c->pad[c->pad_len], pad, pad);
381		✗	av_aes_crypt(c->aes_encrypt, out_buf, c->pad, 1, c->encrypt_iv, 0);
382		✗	ret = ffurl_write(c->hd, out_buf, BLOCKSIZE);
383			}
384
385		✗	ffurl_closep(&c->hd);
386		✗	av_freep(&c->aes_decrypt);
387		✗	av_freep(&c->aes_encrypt);
388		✗	av_freep(&c->write_buf);
389		✗	return ret;
390			}
391
392			const URLProtocol ff_crypto_protocol = {
393			.name = "crypto",
394			.url_open2 = crypto_open2,
395			.url_seek = crypto_seek,
396			.url_read = crypto_read,
397			.url_write = crypto_write,
398			.url_close = crypto_close,
399			.priv_data_size = sizeof(CryptoContext),
400			.priv_data_class = &crypto_class,
401			.flags = URL_PROTOCOL_FLAG_NESTED_SCHEME,
402			};
403