summaryrefslogtreecommitdiffstats
path: root/addrfilt.c
blob: dd1670035194ecd10f2ec5885eecd1855f1e2cf2 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
/*
  chronyd/chronyc - Programs for keeping computer clocks accurate.

 **********************************************************************
 * Copyright (C) Richard P. Curnow  1997,1998,1999,2000,2001,2002,2005
 * Copyright (C) Miroslav Lichvar  2009, 2015
 * 
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of version 2 of the GNU General Public License as
 * published by the Free Software Foundation.
 * 
 * This program 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 this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 * 
 **********************************************************************

  =======================================================================

  This module provides a set of routines for checking IP addresses
  against a set of rules and deciding whether they are allowed or
  disallowed.

  */

#include "config.h"

#include "sysincl.h"

#include "addrfilt.h"
#include "memory.h"

/* Define the number of bits which are stripped off per level of
   indirection in the tables */
#define NBITS 4

/* Define the table size */
#define TABLE_SIZE (1UL<<NBITS)

typedef enum {DENY, ALLOW, AS_PARENT} State;

typedef struct _TableNode {
  State state;
  struct _TableNode *extended;
} TableNode;

struct ADF_AuthTableInst {
  TableNode base4;      /* IPv4 node */
  TableNode base6;      /* IPv6 node */
};

/* ================================================== */

static void
split_ip6(IPAddr *ip, uint32_t *dst)
{
  int i;

  for (i = 0; i < 4; i++)
    dst[i] = (uint32_t)ip->addr.in6[i * 4 + 0] << 24 |
             ip->addr.in6[i * 4 + 1] << 16 |
             ip->addr.in6[i * 4 + 2] << 8 |
             ip->addr.in6[i * 4 + 3];
}

/* ================================================== */

inline static uint32_t
get_subnet(uint32_t *addr, unsigned int where)
{
  int off;

  off = where / 32;
  where %= 32;

  return (addr[off] >> (32 - NBITS - where)) & ((1UL << NBITS) - 1);
}

/* ================================================== */

ADF_AuthTable
ADF_CreateTable(void)
{
  ADF_AuthTable result;
  result = MallocNew(struct ADF_AuthTableInst);

  /* Default is that nothing is allowed */
  result->base4.state = DENY;
  result->base4.extended = NULL;
  result->base6.state = DENY;
  result->base6.extended = NULL;

  return result;
}

/* ================================================== */
/* This function deletes all definitions of child nodes, in effect
   pruning a whole subnet definition back to a single parent
   record. */
static void
close_node(TableNode *node)
{
  int i;
  TableNode *child_node;

  if (node->extended != NULL) {
    for (i=0; i<TABLE_SIZE; i++) {
      child_node = &(node->extended[i]);
      close_node(child_node);
    }
    Free(node->extended);
    node->extended = NULL;
  }
}


/* ================================================== */
/* Allocate the extension field in a node, and set all the children's
   states to default to that of the node being extended */

static void
open_node(TableNode *node)
{
  int i;
  TableNode *child_node;

  if (node->extended == NULL) {

    node->extended = MallocArray(struct _TableNode, TABLE_SIZE);

    for (i=0; i<TABLE_SIZE; i++) {
      child_node = &(node->extended[i]);
      child_node->state = AS_PARENT;
      child_node->extended = NULL;
    }
  }
}

/* ================================================== */

static ADF_Status
set_subnet(TableNode *start_node,
           uint32_t *ip,
           int ip_len,
           int subnet_bits,
           State new_state,
           int delete_children)
{
  int bits_to_go, bits_consumed;
  uint32_t subnet;
  TableNode *node;

  bits_consumed = 0;
  bits_to_go = subnet_bits;
  node = start_node;

  if ((subnet_bits < 0) ||
      (subnet_bits > 32 * ip_len)) {

    return ADF_BADSUBNET;

  } else {

    if ((bits_to_go & (NBITS-1)) == 0) {
    
      while (bits_to_go > 0) {
        subnet = get_subnet(ip, bits_consumed);
        if (!(node->extended)) {
          open_node(node);
        }
        node = &(node->extended[subnet]);
        bits_to_go -= NBITS;
        bits_consumed += NBITS;
      }

      if (delete_children) {
        close_node(node);
      }
      node->state = new_state;

    } else { /* Have to set multiple entries */
      int N, i, j;
      TableNode *this_node;

      while (bits_to_go >= NBITS) {
        subnet = get_subnet(ip, bits_consumed);
        if (!(node->extended)) {
          open_node(node);
        }
        node = &(node->extended[subnet]);
        bits_to_go -= NBITS;
        bits_consumed += NBITS;
      }

      /* How many subnet entries to set : 1->8, 2->4, 3->2 */
      N = 1 << (NBITS-bits_to_go);

      subnet = get_subnet(ip, bits_consumed) & ~(N - 1);
      assert(subnet + N <= TABLE_SIZE);

      if (!(node->extended)) {
        open_node(node);
      }
      
      for (i=subnet, j=0; j<N; i++, j++) {
        this_node = &(node->extended[i]);
        if (delete_children) {
          close_node(this_node);
        }
        this_node->state = new_state;
      }
    }
    
    return ADF_SUCCESS;
  }
  
}

/* ================================================== */

static ADF_Status
set_subnet_(ADF_AuthTable table,
           IPAddr *ip_addr,
           int subnet_bits,
           State new_state,
           int delete_children)
{
  uint32_t ip6[4];

  switch (ip_addr->family) {
    case IPADDR_INET4:
      return set_subnet(&table->base4, &ip_addr->addr.in4, 1, subnet_bits, new_state, delete_children);
    case IPADDR_INET6:
      split_ip6(ip_addr, ip6);
      return set_subnet(&table->base6, ip6, 4, subnet_bits, new_state, delete_children);
    case IPADDR_UNSPEC:
      /* Apply to both, subnet_bits has to be 0 */
      if (subnet_bits != 0)
        return ADF_BADSUBNET;
      memset(ip6, 0, sizeof (ip6));
      if (set_subnet(&table->base4, ip6, 1, 0, new_state, delete_children) == ADF_SUCCESS &&
          set_subnet(&table->base6, ip6, 4, 0, new_state, delete_children) == ADF_SUCCESS)
        return ADF_SUCCESS;
      break;
  }

  return ADF_BADSUBNET;
}

ADF_Status
ADF_Allow(ADF_AuthTable table,
          IPAddr *ip,
          int subnet_bits)
{
  return set_subnet_(table, ip, subnet_bits, ALLOW, 0);
}

/* ================================================== */


ADF_Status
ADF_AllowAll(ADF_AuthTable table,
             IPAddr *ip,
             int subnet_bits)
{
  return set_subnet_(table, ip, subnet_bits, ALLOW, 1);
}

/* ================================================== */

ADF_Status
ADF_Deny(ADF_AuthTable table,
         IPAddr *ip,
         int subnet_bits)
{
  return set_subnet_(table, ip, subnet_bits, DENY, 0);
}

/* ================================================== */

ADF_Status
ADF_DenyAll(ADF_AuthTable table,
            IPAddr *ip,
            int subnet_bits)
{
  return set_subnet_(table, ip, subnet_bits, DENY, 1);
}

/* ================================================== */

void
ADF_DestroyTable(ADF_AuthTable table)
{
  close_node(&table->base4);
  close_node(&table->base6);
  Free(table);
}

/* ================================================== */

static int
check_ip_in_node(TableNode *start_node, uint32_t *ip)
{
  uint32_t subnet;
  int bits_consumed = 0;
  int result = 0;
  int finished = 0;
  TableNode *node;
  State state=DENY;

  node = start_node;

  do {
    if (node->state != AS_PARENT) {
      state = node->state;
    }
    if (node->extended) {
      subnet = get_subnet(ip, bits_consumed);
      node = &(node->extended[subnet]);
      bits_consumed += NBITS;
    } else {
      /* Make decision on this node */
      finished = 1;
    }
  } while (!finished);

  switch (state) {
    case ALLOW:
      result = 1;
      break;
    case DENY:
      result = 0;
      break;
    case AS_PARENT:
      assert(0);
      break;
  }

  return result;
}


/* ================================================== */

int
ADF_IsAllowed(ADF_AuthTable table,
              IPAddr *ip_addr)
{
  uint32_t ip6[4];

  switch (ip_addr->family) {
    case IPADDR_INET4:
      return check_ip_in_node(&table->base4, &ip_addr->addr.in4);
    case IPADDR_INET6:
      split_ip6(ip_addr, ip6);
      return check_ip_in_node(&table->base6, ip6);
  }

  return 0;
}

/* ================================================== */

static int
is_any_allowed(TableNode *node, State parent)
{
  State state;
  int i;

  state = node->state != AS_PARENT ? node->state : parent;
  assert(state != AS_PARENT);

  if (node->extended) {
    for (i = 0; i < TABLE_SIZE; i++) {
      if (is_any_allowed(&node->extended[i], state))
        return 1;
    }
  } else if (state == ALLOW) {
    return 1;
  }

  return 0;
}

/* ================================================== */

int
ADF_IsAnyAllowed(ADF_AuthTable table, int family)
{
  switch (family) {
    case IPADDR_INET4:
      return is_any_allowed(&table->base4, AS_PARENT);
    case IPADDR_INET6:
      return is_any_allowed(&table->base6, AS_PARENT);
    default:
      return 0;
  }
}