1/* crypto/evp/bio_ok.c */
2/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
3 * All rights reserved.
4 *
5 * This package is an SSL implementation written
6 * by Eric Young (eay@cryptsoft.com).
7 * The implementation was written so as to conform with Netscapes SSL.
8 *
9 * This library is free for commercial and non-commercial use as long as
10 * the following conditions are aheared to.  The following conditions
11 * apply to all code found in this distribution, be it the RC4, RSA,
12 * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
13 * included with this distribution is covered by the same copyright terms
14 * except that the holder is Tim Hudson (tjh@cryptsoft.com).
15 *
16 * Copyright remains Eric Young's, and as such any Copyright notices in
17 * the code are not to be removed.
18 * If this package is used in a product, Eric Young should be given attribution
19 * as the author of the parts of the library used.
20 * This can be in the form of a textual message at program startup or
21 * in documentation (online or textual) provided with the package.
22 *
23 * Redistribution and use in source and binary forms, with or without
24 * modification, are permitted provided that the following conditions
25 * are met:
26 * 1. Redistributions of source code must retain the copyright
27 *    notice, this list of conditions and the following disclaimer.
28 * 2. Redistributions in binary form must reproduce the above copyright
29 *    notice, this list of conditions and the following disclaimer in the
30 *    documentation and/or other materials provided with the distribution.
31 * 3. All advertising materials mentioning features or use of this software
32 *    must display the following acknowledgement:
33 *    "This product includes cryptographic software written by
34 *     Eric Young (eay@cryptsoft.com)"
35 *    The word 'cryptographic' can be left out if the rouines from the library
36 *    being used are not cryptographic related :-).
37 * 4. If you include any Windows specific code (or a derivative thereof) from
38 *    the apps directory (application code) you must include an acknowledgement:
39 *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
40 *
41 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
42 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
43 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
44 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
45 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
46 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
47 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
48 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
49 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
50 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
51 * SUCH DAMAGE.
52 *
53 * The licence and distribution terms for any publically available version or
54 * derivative of this code cannot be changed.  i.e. this code cannot simply be
55 * copied and put under another distribution licence
56 * [including the GNU Public Licence.]
57 */
58
59/*
60	From: Arne Ansper <arne@cyber.ee>
61
62	Why BIO_f_reliable?
63
64	I wrote function which took BIO* as argument, read data from it
65	and processed it. Then I wanted to store the input file in
66	encrypted form. OK I pushed BIO_f_cipher to the BIO stack
67	and everything was OK. BUT if user types wrong password
68	BIO_f_cipher outputs only garbage and my function crashes. Yes
69	I can and I should fix my function, but BIO_f_cipher is
70	easy way to add encryption support to many existing applications
71	and it's hard to debug and fix them all.
72
73	So I wanted another BIO which would catch the incorrect passwords and
74	file damages which cause garbage on BIO_f_cipher's output.
75
76	The easy way is to push the BIO_f_md and save the checksum at
77	the end of the file. However there are several problems with this
78	approach:
79
80	1) you must somehow separate checksum from actual data.
81	2) you need lot's of memory when reading the file, because you
82	must read to the end of the file and verify the checksum before
83	letting the application to read the data.
84
85	BIO_f_reliable tries to solve both problems, so that you can
86	read and write arbitrary long streams using only fixed amount
87	of memory.
88
89	BIO_f_reliable splits data stream into blocks. Each block is prefixed
90	with it's length and suffixed with it's digest. So you need only
91	several Kbytes of memory to buffer single block before verifying
92	it's digest.
93
94	BIO_f_reliable goes further and adds several important capabilities:
95
96	1) the digest of the block is computed over the whole stream
97	-- so nobody can rearrange the blocks or remove or replace them.
98
99	2) to detect invalid passwords right at the start BIO_f_reliable
100	adds special prefix to the stream. In order to avoid known plain-text
101	attacks this prefix is generated as follows:
102
103		*) digest is initialized with random seed instead of
104		standardized one.
105		*) same seed is written to output
106		*) well-known text is then hashed and the output
107		of the digest is also written to output.
108
109	reader can now read the seed from stream, hash the same string
110	and then compare the digest output.
111
112	Bad things: BIO_f_reliable knows what's going on in EVP_Digest. I
113	initially wrote and tested this code on x86 machine and wrote the
114	digests out in machine-dependent order :( There are people using
115	this code and I cannot change this easily without making existing
116	data files unreadable.
117
118*/
119
120#include <stdio.h>
121#include <errno.h>
122#include <assert.h>
123#include "cryptlib.h"
124#include <openssl/buffer.h>
125#include <openssl/bio.h>
126#include <openssl/evp.h>
127#include <openssl/rand.h>
128
129static int ok_write(BIO *h, const char *buf, int num);
130static int ok_read(BIO *h, char *buf, int size);
131static long ok_ctrl(BIO *h, int cmd, long arg1, void *arg2);
132static int ok_new(BIO *h);
133static int ok_free(BIO *data);
134static long ok_callback_ctrl(BIO *h, int cmd, bio_info_cb *fp);
135
136static int sig_out(BIO* b);
137static int sig_in(BIO* b);
138static int block_out(BIO* b);
139static int block_in(BIO* b);
140#define OK_BLOCK_SIZE	(1024*4)
141#define OK_BLOCK_BLOCK	4
142#define IOBS		(OK_BLOCK_SIZE+ OK_BLOCK_BLOCK+ 3*EVP_MAX_MD_SIZE)
143#define WELLKNOWN "The quick brown fox jumped over the lazy dog's back."
144
145typedef struct ok_struct
146	{
147	size_t buf_len;
148	size_t buf_off;
149	size_t buf_len_save;
150	size_t buf_off_save;
151	int cont;		/* <= 0 when finished */
152	int finished;
153	EVP_MD_CTX md;
154	int blockout;		/* output block is ready */
155	int sigio;		/* must process signature */
156	unsigned char buf[IOBS];
157	} BIO_OK_CTX;
158
159static BIO_METHOD methods_ok=
160	{
161	BIO_TYPE_CIPHER,"reliable",
162	ok_write,
163	ok_read,
164	NULL, /* ok_puts, */
165	NULL, /* ok_gets, */
166	ok_ctrl,
167	ok_new,
168	ok_free,
169	ok_callback_ctrl,
170	};
171
172BIO_METHOD *BIO_f_reliable(void)
173	{
174	return(&methods_ok);
175	}
176
177static int ok_new(BIO *bi)
178	{
179	BIO_OK_CTX *ctx;
180
181	ctx=(BIO_OK_CTX *)OPENSSL_malloc(sizeof(BIO_OK_CTX));
182	if (ctx == NULL) return(0);
183
184	ctx->buf_len=0;
185	ctx->buf_off=0;
186	ctx->buf_len_save=0;
187	ctx->buf_off_save=0;
188	ctx->cont=1;
189	ctx->finished=0;
190	ctx->blockout= 0;
191	ctx->sigio=1;
192
193	EVP_MD_CTX_init(&ctx->md);
194
195	bi->init=0;
196	bi->ptr=(char *)ctx;
197	bi->flags=0;
198	return(1);
199	}
200
201static int ok_free(BIO *a)
202	{
203	if (a == NULL) return(0);
204	EVP_MD_CTX_cleanup(&((BIO_OK_CTX *)a->ptr)->md);
205	OPENSSL_cleanse(a->ptr,sizeof(BIO_OK_CTX));
206	OPENSSL_free(a->ptr);
207	a->ptr=NULL;
208	a->init=0;
209	a->flags=0;
210	return(1);
211	}
212
213static int ok_read(BIO *b, char *out, int outl)
214	{
215	int ret=0,i,n;
216	BIO_OK_CTX *ctx;
217
218	if (out == NULL) return(0);
219	ctx=(BIO_OK_CTX *)b->ptr;
220
221	if ((ctx == NULL) || (b->next_bio == NULL) || (b->init == 0)) return(0);
222
223	while(outl > 0)
224		{
225
226		/* copy clean bytes to output buffer */
227		if (ctx->blockout)
228			{
229			i=ctx->buf_len-ctx->buf_off;
230			if (i > outl) i=outl;
231			memcpy(out,&(ctx->buf[ctx->buf_off]),i);
232			ret+=i;
233			out+=i;
234			outl-=i;
235			ctx->buf_off+=i;
236
237			/* all clean bytes are out */
238			if (ctx->buf_len == ctx->buf_off)
239				{
240				ctx->buf_off=0;
241
242				/* copy start of the next block into proper place */
243				if(ctx->buf_len_save- ctx->buf_off_save > 0)
244					{
245					ctx->buf_len= ctx->buf_len_save- ctx->buf_off_save;
246					memmove(ctx->buf, &(ctx->buf[ctx->buf_off_save]),
247							ctx->buf_len);
248					}
249				else
250					{
251					ctx->buf_len=0;
252					}
253				ctx->blockout= 0;
254				}
255			}
256
257		/* output buffer full -- cancel */
258		if (outl == 0) break;
259
260		/* no clean bytes in buffer -- fill it */
261		n=IOBS- ctx->buf_len;
262		i=BIO_read(b->next_bio,&(ctx->buf[ctx->buf_len]),n);
263
264		if (i <= 0) break;	/* nothing new */
265
266		ctx->buf_len+= i;
267
268		/* no signature yet -- check if we got one */
269		if (ctx->sigio == 1)
270			{
271			if (!sig_in(b))
272				{
273				BIO_clear_retry_flags(b);
274				return 0;
275				}
276			}
277
278		/* signature ok -- check if we got block */
279		if (ctx->sigio == 0)
280			{
281			if (!block_in(b))
282				{
283				BIO_clear_retry_flags(b);
284				return 0;
285				}
286			}
287
288		/* invalid block -- cancel */
289		if (ctx->cont <= 0) break;
290
291		}
292
293	BIO_clear_retry_flags(b);
294	BIO_copy_next_retry(b);
295	return(ret);
296	}
297
298static int ok_write(BIO *b, const char *in, int inl)
299	{
300	int ret=0,n,i;
301	BIO_OK_CTX *ctx;
302
303	if (inl <= 0) return inl;
304
305	ctx=(BIO_OK_CTX *)b->ptr;
306	ret=inl;
307
308	if ((ctx == NULL) || (b->next_bio == NULL) || (b->init == 0)) return(0);
309
310	if(ctx->sigio && !sig_out(b))
311		return 0;
312
313	do{
314		BIO_clear_retry_flags(b);
315		n=ctx->buf_len-ctx->buf_off;
316		while (ctx->blockout && n > 0)
317			{
318			i=BIO_write(b->next_bio,&(ctx->buf[ctx->buf_off]),n);
319			if (i <= 0)
320				{
321				BIO_copy_next_retry(b);
322				if(!BIO_should_retry(b))
323					ctx->cont= 0;
324				return(i);
325				}
326			ctx->buf_off+=i;
327			n-=i;
328			}
329
330		/* at this point all pending data has been written */
331		ctx->blockout= 0;
332		if (ctx->buf_len == ctx->buf_off)
333			{
334			ctx->buf_len=OK_BLOCK_BLOCK;
335			ctx->buf_off=0;
336			}
337
338		if ((in == NULL) || (inl <= 0)) return(0);
339
340		n= (inl+ ctx->buf_len > OK_BLOCK_SIZE+ OK_BLOCK_BLOCK) ?
341			(int)(OK_BLOCK_SIZE+OK_BLOCK_BLOCK-ctx->buf_len) : inl;
342
343		memcpy((unsigned char *)(&(ctx->buf[ctx->buf_len])),(unsigned char *)in,n);
344		ctx->buf_len+= n;
345		inl-=n;
346		in+=n;
347
348		if(ctx->buf_len >= OK_BLOCK_SIZE+ OK_BLOCK_BLOCK)
349			{
350			if (!block_out(b))
351				{
352				BIO_clear_retry_flags(b);
353				return 0;
354				}
355			}
356	}while(inl > 0);
357
358	BIO_clear_retry_flags(b);
359	BIO_copy_next_retry(b);
360	return(ret);
361	}
362
363static long ok_ctrl(BIO *b, int cmd, long num, void *ptr)
364	{
365	BIO_OK_CTX *ctx;
366	EVP_MD *md;
367	const EVP_MD **ppmd;
368	long ret=1;
369	int i;
370
371	ctx=b->ptr;
372
373	switch (cmd)
374		{
375	case BIO_CTRL_RESET:
376		ctx->buf_len=0;
377		ctx->buf_off=0;
378		ctx->buf_len_save=0;
379		ctx->buf_off_save=0;
380		ctx->cont=1;
381		ctx->finished=0;
382		ctx->blockout= 0;
383		ctx->sigio=1;
384		ret=BIO_ctrl(b->next_bio,cmd,num,ptr);
385		break;
386	case BIO_CTRL_EOF:	/* More to read */
387		if (ctx->cont <= 0)
388			ret=1;
389		else
390			ret=BIO_ctrl(b->next_bio,cmd,num,ptr);
391		break;
392	case BIO_CTRL_PENDING: /* More to read in buffer */
393	case BIO_CTRL_WPENDING: /* More to read in buffer */
394		ret=ctx->blockout ? ctx->buf_len-ctx->buf_off : 0;
395		if (ret <= 0)
396			ret=BIO_ctrl(b->next_bio,cmd,num,ptr);
397		break;
398	case BIO_CTRL_FLUSH:
399		/* do a final write */
400		if(ctx->blockout == 0)
401			if (!block_out(b))
402				return 0;
403
404		while (ctx->blockout)
405			{
406			i=ok_write(b,NULL,0);
407			if (i < 0)
408				{
409				ret=i;
410				break;
411				}
412			}
413
414		ctx->finished=1;
415		ctx->buf_off=ctx->buf_len=0;
416		ctx->cont=(int)ret;
417
418		/* Finally flush the underlying BIO */
419		ret=BIO_ctrl(b->next_bio,cmd,num,ptr);
420		break;
421	case BIO_C_DO_STATE_MACHINE:
422		BIO_clear_retry_flags(b);
423		ret=BIO_ctrl(b->next_bio,cmd,num,ptr);
424		BIO_copy_next_retry(b);
425		break;
426	case BIO_CTRL_INFO:
427		ret=(long)ctx->cont;
428		break;
429	case BIO_C_SET_MD:
430		md=ptr;
431		if (!EVP_DigestInit_ex(&ctx->md, md, NULL))
432			return 0;
433		b->init=1;
434		break;
435	case BIO_C_GET_MD:
436		if (b->init)
437			{
438			ppmd=ptr;
439			*ppmd=ctx->md.digest;
440			}
441		else
442			ret=0;
443		break;
444	default:
445		ret=BIO_ctrl(b->next_bio,cmd,num,ptr);
446		break;
447		}
448	return(ret);
449	}
450
451static long ok_callback_ctrl(BIO *b, int cmd, bio_info_cb *fp)
452	{
453	long ret=1;
454
455	if (b->next_bio == NULL) return(0);
456	switch (cmd)
457		{
458	default:
459		ret=BIO_callback_ctrl(b->next_bio,cmd,fp);
460		break;
461		}
462	return(ret);
463	}
464
465static void longswap(void *_ptr, size_t len)
466{	const union { long one; char little; } is_endian = {1};
467
468	if (is_endian.little) {
469		size_t i;
470		unsigned char *p=_ptr,c;
471
472		for(i= 0;i < len;i+= 4) {
473			c=p[0],p[0]=p[3],p[3]=c;
474			c=p[1],p[1]=p[2],p[2]=c;
475		}
476	}
477}
478
479static int sig_out(BIO* b)
480	{
481	BIO_OK_CTX *ctx;
482	EVP_MD_CTX *md;
483
484	ctx=b->ptr;
485	md=&ctx->md;
486
487	if(ctx->buf_len+ 2* md->digest->md_size > OK_BLOCK_SIZE) return 1;
488
489	if (!EVP_DigestInit_ex(md, md->digest, NULL))
490		goto berr;
491	/* FIXME: there's absolutely no guarantee this makes any sense at all,
492	 * particularly now EVP_MD_CTX has been restructured.
493	 */
494	RAND_pseudo_bytes(md->md_data, md->digest->md_size);
495	memcpy(&(ctx->buf[ctx->buf_len]), md->md_data, md->digest->md_size);
496	longswap(&(ctx->buf[ctx->buf_len]), md->digest->md_size);
497	ctx->buf_len+= md->digest->md_size;
498
499	if (!EVP_DigestUpdate(md, WELLKNOWN, strlen(WELLKNOWN)))
500		goto berr;
501	if (!EVP_DigestFinal_ex(md, &(ctx->buf[ctx->buf_len]), NULL))
502		goto berr;
503	ctx->buf_len+= md->digest->md_size;
504	ctx->blockout= 1;
505	ctx->sigio= 0;
506	return 1;
507	berr:
508	BIO_clear_retry_flags(b);
509	return 0;
510	}
511
512static int sig_in(BIO* b)
513	{
514	BIO_OK_CTX *ctx;
515	EVP_MD_CTX *md;
516	unsigned char tmp[EVP_MAX_MD_SIZE];
517	int ret= 0;
518
519	ctx=b->ptr;
520	md=&ctx->md;
521
522	if((int)(ctx->buf_len-ctx->buf_off) < 2*md->digest->md_size) return 1;
523
524	if (!EVP_DigestInit_ex(md, md->digest, NULL))
525		goto berr;
526	memcpy(md->md_data, &(ctx->buf[ctx->buf_off]), md->digest->md_size);
527	longswap(md->md_data, md->digest->md_size);
528	ctx->buf_off+= md->digest->md_size;
529
530	if (!EVP_DigestUpdate(md, WELLKNOWN, strlen(WELLKNOWN)))
531		goto berr;
532	if (!EVP_DigestFinal_ex(md, tmp, NULL))
533		goto berr;
534	ret= memcmp(&(ctx->buf[ctx->buf_off]), tmp, md->digest->md_size) == 0;
535	ctx->buf_off+= md->digest->md_size;
536	if(ret == 1)
537		{
538		ctx->sigio= 0;
539		if(ctx->buf_len != ctx->buf_off)
540			{
541			memmove(ctx->buf, &(ctx->buf[ctx->buf_off]), ctx->buf_len- ctx->buf_off);
542			}
543		ctx->buf_len-= ctx->buf_off;
544		ctx->buf_off= 0;
545		}
546	else
547		{
548		ctx->cont= 0;
549		}
550	return 1;
551	berr:
552	BIO_clear_retry_flags(b);
553	return 0;
554	}
555
556static int block_out(BIO* b)
557	{
558	BIO_OK_CTX *ctx;
559	EVP_MD_CTX *md;
560	unsigned long tl;
561
562	ctx=b->ptr;
563	md=&ctx->md;
564
565	tl= ctx->buf_len- OK_BLOCK_BLOCK;
566	ctx->buf[0]=(unsigned char)(tl>>24);
567	ctx->buf[1]=(unsigned char)(tl>>16);
568	ctx->buf[2]=(unsigned char)(tl>>8);
569	ctx->buf[3]=(unsigned char)(tl);
570	if (!EVP_DigestUpdate(md,
571		(unsigned char*) &(ctx->buf[OK_BLOCK_BLOCK]), tl))
572		goto berr;
573	if (!EVP_DigestFinal_ex(md, &(ctx->buf[ctx->buf_len]), NULL))
574		goto berr;
575	ctx->buf_len+= md->digest->md_size;
576	ctx->blockout= 1;
577	return 1;
578	berr:
579	BIO_clear_retry_flags(b);
580	return 0;
581	}
582
583static int block_in(BIO* b)
584	{
585	BIO_OK_CTX *ctx;
586	EVP_MD_CTX *md;
587	unsigned long tl= 0;
588	unsigned char tmp[EVP_MAX_MD_SIZE];
589
590	ctx=b->ptr;
591	md=&ctx->md;
592
593	assert(sizeof(tl)>=OK_BLOCK_BLOCK);	/* always true */
594	tl =ctx->buf[0]; tl<<=8;
595	tl|=ctx->buf[1]; tl<<=8;
596	tl|=ctx->buf[2]; tl<<=8;
597	tl|=ctx->buf[3];
598
599	if (ctx->buf_len < tl+ OK_BLOCK_BLOCK+ md->digest->md_size) return 1;
600
601	if (!EVP_DigestUpdate(md,
602			(unsigned char*) &(ctx->buf[OK_BLOCK_BLOCK]), tl))
603		goto berr;
604	if (!EVP_DigestFinal_ex(md, tmp, NULL))
605		goto berr;
606	if(memcmp(&(ctx->buf[tl+ OK_BLOCK_BLOCK]), tmp, md->digest->md_size) == 0)
607		{
608		/* there might be parts from next block lurking around ! */
609		ctx->buf_off_save= tl+ OK_BLOCK_BLOCK+ md->digest->md_size;
610		ctx->buf_len_save= ctx->buf_len;
611		ctx->buf_off= OK_BLOCK_BLOCK;
612		ctx->buf_len= tl+ OK_BLOCK_BLOCK;
613		ctx->blockout= 1;
614		}
615	else
616		{
617		ctx->cont= 0;
618		}
619	return 1;
620	berr:
621	BIO_clear_retry_flags(b);
622	return 0;
623	}
624
625