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