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