trunk/Src/wptPassCache.cpp

/* wptPassCache.c - keep a cache of passphrases
 *      Copyright (C) 2002 Free Software Foundation, Inc.
 *      Copyright (C) 2003 Timo Schulz
 *
 * This file is part of WinPT.
 *
 * WinPT is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * WinPT is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with WinPT; if not, write to the Free Software Foundation, 
 * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
 */
#include <windows.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <assert.h>

#include "wptTypes.h"
#include "wptErrors.h"
#include "wptAgent.h"


struct secret_data_s {
    int  totallen; /* this includes the padding */
    int  datalen;  /* actual data length */
    char data[1];
};

typedef struct cache_item_s *ITEM;
struct cache_item_s {
    ITEM next;
    time_t created;
    time_t accessed;
    int  ttl;  /* max. lifetime given in seconds */
    int lockcount;
    struct secret_data_s * pw;
    size_t pwlen;
    char key[1];
};


static ITEM thecache;


static void
release_data (struct secret_data_s * data)
{
    free( data );
}


static void
wipe_data (void * data, size_t dlen)
{
    memset( data, 0xff, dlen );
    memset( data, 0xaa, dlen );
    memset( data, 0x55, dlen );
    memset( data, 0x00, dlen );
}


static struct secret_data_s *
new_data( const void * data, size_t length )
{
    struct secret_data_s * d;
    int total;

    /* we pad the data to 32 bytes so that it get more complicated
       finding something out by watching allocation patterns.  This is
       usally not possible but we better assume nothing about our
       secure storage provider*/
    total = length + 32 - (length % 32);

    d = (secret_data_s *)malloc( sizeof *d + total - 1 );
    if( d ) {
        d->totallen = total;
        d->datalen  = length;
        memcpy( d->data, data, length );
    }
    return d;
}


/* check whether there are items to expire */
static void
housekeeping( void )
{
    ITEM r, rprev;
    time_t current = time( NULL );

    /* first expire the actual data */
    for( r=thecache; r; r = r->next ) {
        if( !r->lockcount && r->pw && r->accessed + r->ttl < current ) {
            wipe_data( r->pw, r->pwlen );
            release_data( r->pw );
            r->pw = NULL;
            r->accessed = current;
        }
    }

    /* second, make sure that we also remove them based on the created stamp so
       that the user has to enter it from time to time.  We do this every hour */
    for( r=thecache; r; r = r->next ) {
        if( !r->lockcount && r->pw && r->created + 60*60 < current ) {
            wipe_data( r->pw, r->pwlen );
            release_data( r->pw );
            r->pw = NULL;
            r->accessed = current;
        }
    }

    /* third, make sure that we don't have too many items in the list.
       Expire old and unused entries after 30 minutes */
    for( rprev=NULL, r=thecache; r; ) {
        if (!r->pw && r->accessed + 60*30 < current) {
            if (r->lockcount) {
                BUG( NULL );
                r->accessed += 60*10; /* next error message in 10 minutes */
                rprev = r;
                r = r->next;
            }
            else {
                ITEM r2 = r->next;
                free (r);
                if( !rprev )
                    thecache = r2;
                else
                    rprev->next = r2;
                r = r2;
            }
        }
        else {
            rprev = r;
            r = r->next;
        }
    }
}


void
agent_flush_cache( void )
{
    ITEM r;    

    for( r=thecache; r; r = r->next ) {
        if( !r->lockcount && r->pw ) {
            wipe_data( r->pw, r->pwlen );
            release_data( r->pw );
            r->pw = NULL;
            r->accessed = 0;
        }
        else if( r->lockcount && r->pw ) {
            r->accessed = 0;
            r->ttl = 0;
        }
    }
}


/* Try to find the item given by key and set the TTL value to zero.
   This means the item expires the next time the passphrase cache is used. */
int
agent_del_cache( const char * key )
{
    void * item;
    ITEM r;

    if( agent_get_cache( key, &item ) ) {
        r = (ITEM)item;
        if( r )
            r->ttl = 0;
        agent_unlock_cache_entry( &item );
        return 0;
    }
    return -1;
}


/* Store DATA of length DATALEN in the cache under KEY and mark it
   with a maximum lifetime of TTL seconds.  If there is already data
   under this key, it will be replaced.  Using a DATA of NULL deletes
   the entry */
int
agent_put_cache( const char * key, const char * data, int ttl )
{
    ITEM r;
    
    housekeeping ();

    if (ttl < 1)
        ttl = 5*60;
    if (!ttl)
        return 0;

    for (r=thecache; r; r = r->next) {
        if (!r->lockcount && !strcmp (r->key, key))
            break;
    }
    if( r ) { /* replace */
        if( r->pw ) {
            wipe_data( r->pw, r->pwlen );
            release_data( r->pw );
            r->pw = NULL;
        }
        if (data) {
            r->created = r->accessed = time( NULL );
            r->ttl = ttl;
            r->pwlen = strlen( data );
            r->pw = new_data( data, r->pwlen+1 );
            if (!r->pw)
                BUG( NULL );
        }
    }
    else if (data) { /* simply insert */
        r = (ITEM)calloc (1, sizeof *r + strlen (key));
        if (!r)
            BUG( NULL );
        else {
            strcpy (r->key, key);
            r->created = r->accessed = time( NULL ); 
            r->ttl = ttl;
            r->pwlen = strlen( data );
            r->pw = new_data( data, r->pwlen+1 );
            if (!r->pw)
                BUG( NULL );
            else {
                r->next = thecache;
                thecache = r;
            }
        }
    }
    return 0;
}


/* Try to find an item in the cache */
const char *
agent_get_cache( const char * key, void ** cache_id )
{
    ITEM r;
    
    housekeeping ();

    /* first try to find one with no locks - this is an updated cache
       entry: We might have entries with a lockcount and without a
       lockcount. */
    for (r=thecache; r; r = r->next) {
        if (!r->lockcount && r->pw && !strcmp (r->key, key)) {
            /* put_cache does only put strings into the cache, so we
               don't need the lengths */
            r->accessed = time (NULL);
            r->lockcount++;
            *cache_id = r;
            return r->pw->data;
        }
    }
    /* again, but this time get even one with a lockcount set */
    for (r=thecache; r; r = r->next) {
        if (r->pw && !strcmp (r->key, key)) {
            r->accessed = time (NULL);
            r->lockcount++;
            *cache_id = r;
            return r->pw->data;
        }
    }    

    *cache_id = NULL;
    return NULL;
}


void
agent_unlock_cache_entry( void ** cache_id )
{
    ITEM r;

    for( r=thecache; r; r = r->next ) {
        if( r == *cache_id ) {
            if( !r->lockcount )
                BUG( NULL );
            else
                r->lockcount--;
            return;
        }
    }
}
1	/* wptPassCache.c - keep a cache of passphrases
2	* Copyright (C) 2002 Free Software Foundation, Inc.
3	* Copyright (C) 2003 Timo Schulz
4	*
5	* This file is part of WinPT.
6	*
7	* WinPT is free software; you can redistribute it and/or modify
8	* it under the terms of the GNU General Public License as published by
9	* the Free Software Foundation; either version 2 of the License, or
10	* (at your option) any later version.
11	*
12	* WinPT 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
15	* GNU General Public License for more details.
16	*
17	* You should have received a copy of the GNU General Public License
18	* along with WinPT; if not, write to the Free Software Foundation,
19	* Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
20	*/
21	#include <windows.h>
22	#include <stdio.h>
23	#include <stdlib.h>
24	#include <string.h>
25	#include <time.h>
26	#include <assert.h>
27
28	#include "wptTypes.h"
29	#include "wptErrors.h"
30	#include "wptAgent.h"
31
32
33	struct secret_data_s {
34	int totallen; /* this includes the padding */
35	int datalen; /* actual data length */
36	char data[1];
37	};
38
39	typedef struct cache_item_s *ITEM;
40	struct cache_item_s {
41	ITEM next;
42	time_t created;
43	time_t accessed;
44	int ttl; /* max. lifetime given in seconds */
45	int lockcount;
46	struct secret_data_s * pw;
47	size_t pwlen;
48	char key[1];
49	};
50
51
52	static ITEM thecache;
53
54
55	static void
56	release_data (struct secret_data_s * data)
57	{
58	free( data );
59	}
60
61
62	static void
63	wipe_data (void * data, size_t dlen)
64	{
65	memset( data, 0xff, dlen );
66	memset( data, 0xaa, dlen );
67	memset( data, 0x55, dlen );
68	memset( data, 0x00, dlen );
69	}
70
71
72	static struct secret_data_s *
73	new_data( const void * data, size_t length )
74	{
75	struct secret_data_s * d;
76	int total;
77
78	/* we pad the data to 32 bytes so that it get more complicated
79	finding something out by watching allocation patterns. This is
80	usally not possible but we better assume nothing about our
81	secure storage provider*/
82	total = length + 32 - (length % 32);
83
84	d = (secret_data_s )malloc( sizeof d + total - 1 );
85	if( d ) {
86	d->totallen = total;
87	d->datalen = length;
88	memcpy( d->data, data, length );
89	}
90	return d;
91	}
92
93
94	/* check whether there are items to expire */
95	static void
96	housekeeping( void )
97	{
98	ITEM r, rprev;
99	time_t current = time( NULL );
100
101	/* first expire the actual data */
102	for( r=thecache; r; r = r->next ) {
103	if( !r->lockcount && r->pw && r->accessed + r->ttl < current ) {
104	wipe_data( r->pw, r->pwlen );
105	release_data( r->pw );
106	r->pw = NULL;
107	r->accessed = current;
108	}
109	}
110
111	/* second, make sure that we also remove them based on the created stamp so
112	that the user has to enter it from time to time. We do this every hour */
113	for( r=thecache; r; r = r->next ) {
114	if( !r->lockcount && r->pw && r->created + 60*60 < current ) {
115	wipe_data( r->pw, r->pwlen );
116	release_data( r->pw );
117	r->pw = NULL;
118	r->accessed = current;
119	}
120	}
121
122	/* third, make sure that we don't have too many items in the list.
123	Expire old and unused entries after 30 minutes */
124	for( rprev=NULL, r=thecache; r; ) {
125	if (!r->pw && r->accessed + 60*30 < current) {
126	if (r->lockcount) {
127	BUG( NULL );
128	r->accessed += 6010; / next error message in 10 minutes */
129	rprev = r;
130	r = r->next;
131	}
132	else {
133	ITEM r2 = r->next;
134	free (r);
135	if( !rprev )
136	thecache = r2;
137	else
138	rprev->next = r2;
139	r = r2;
140	}
141	}
142	else {
143	rprev = r;
144	r = r->next;
145	}
146	}
147	}
148
149
150	void
151	agent_flush_cache( void )
152	{
153	ITEM r;
154
155	for( r=thecache; r; r = r->next ) {
156	if( !r->lockcount && r->pw ) {
157	wipe_data( r->pw, r->pwlen );
158	release_data( r->pw );
159	r->pw = NULL;
160	r->accessed = 0;
161	}
162	else if( r->lockcount && r->pw ) {
163	r->accessed = 0;
164	r->ttl = 0;
165	}
166	}
167	}
168
169
170	/* Try to find the item given by key and set the TTL value to zero.
171	This means the item expires the next time the passphrase cache is used. */
172	int
173	agent_del_cache( const char * key )
174	{
175	void * item;
176	ITEM r;
177
178	if( agent_get_cache( key, &item ) ) {
179	r = (ITEM)item;
180	if( r )
181	r->ttl = 0;
182	agent_unlock_cache_entry( &item );
183	return 0;
184	}
185	return -1;
186	}
187
188
189	/* Store DATA of length DATALEN in the cache under KEY and mark it
190	with a maximum lifetime of TTL seconds. If there is already data
191	under this key, it will be replaced. Using a DATA of NULL deletes
192	the entry */
193	int
194	agent_put_cache( const char * key, const char * data, int ttl )
195	{
196	ITEM r;
197
198	housekeeping ();
199
200	if (ttl < 1)
201	ttl = 5*60;
202	if (!ttl)
203	return 0;
204
205	for (r=thecache; r; r = r->next) {
206	if (!r->lockcount && !strcmp (r->key, key))
207	break;
208	}
209	if( r ) { /* replace */
210	if( r->pw ) {
211	wipe_data( r->pw, r->pwlen );
212	release_data( r->pw );
213	r->pw = NULL;
214	}
215	if (data) {
216	r->created = r->accessed = time( NULL );
217	r->ttl = ttl;
218	r->pwlen = strlen( data );
219	r->pw = new_data( data, r->pwlen+1 );
220	if (!r->pw)
221	BUG( NULL );
222	}
223	}
224	else if (data) { /* simply insert */
225	r = (ITEM)calloc (1, sizeof *r + strlen (key));
226	if (!r)
227	BUG( NULL );
228	else {
229	strcpy (r->key, key);
230	r->created = r->accessed = time( NULL );
231	r->ttl = ttl;
232	r->pwlen = strlen( data );
233	r->pw = new_data( data, r->pwlen+1 );
234	if (!r->pw)
235	BUG( NULL );
236	else {
237	r->next = thecache;
238	thecache = r;
239	}
240	}
241	}
242	return 0;
243	}
244
245
246	/* Try to find an item in the cache */
247	const char *
248	agent_get_cache( const char * key, void ** cache_id )
249	{
250	ITEM r;
251
252	housekeeping ();
253
254	/* first try to find one with no locks - this is an updated cache
255	entry: We might have entries with a lockcount and without a
256	lockcount. */
257	for (r=thecache; r; r = r->next) {
258	if (!r->lockcount && r->pw && !strcmp (r->key, key)) {
259	/* put_cache does only put strings into the cache, so we
260	don't need the lengths */
261	r->accessed = time (NULL);
262	r->lockcount++;
263	*cache_id = r;
264	return r->pw->data;
265	}
266	}
267	/* again, but this time get even one with a lockcount set */
268	for (r=thecache; r; r = r->next) {
269	if (r->pw && !strcmp (r->key, key)) {
270	r->accessed = time (NULL);
271	r->lockcount++;
272	*cache_id = r;
273	return r->pw->data;
274	}
275	}
276
277	*cache_id = NULL;
278	return NULL;
279	}
280
281
282	void
283	agent_unlock_cache_entry( void ** cache_id )
284	{
285	ITEM r;
286
287	for( r=thecache; r; r = r->next ) {
288	if( r == *cache_id ) {
289	if( !r->lockcount )
290	BUG( NULL );
291	else
292	r->lockcount--;
293	return;
294	}
295	}
296	}