libiptc/libip6tc.c

   1 /* Library which manipulates firewall rules.  Version 0.1. */
   2
   3 /* Architecture of firewall rules is as follows:
   4  *
   5  * Chains go INPUT, FORWARD, OUTPUT then user chains.
   6  * Each user chain starts with an ERROR node.
   7  * Every chain ends with an unconditional jump: a RETURN for user chains,
   8  * and a POLICY for built-ins.
   9  */
  10
  11 /* (C)1999 Paul ``Rusty'' Russell - Placed under the GNU GPL (See
  12    COPYING for details). */
  13
  14 #include <assert.h>
  15 #include <string.h>
  16 #include <errno.h>
  17 #include <stdlib.h>
  18 #include <stdio.h>
  19 #include <unistd.h>
  20 #include <arpa/inet.h>
  21
  22 #ifdef DEBUG_CONNTRACK
  23 #define inline
  24 #endif
  25
  26 #if !defined(__GLIBC__) || (__GLIBC__ < 2)
  27 typedef unsigned int socklen_t;
  28 #endif
  29
  30 #include "libiptc/libip6tc.h"
  31
  32 #define HOOK_PRE_ROUTING        NF_IP6_PRE_ROUTING
  33 #define HOOK_LOCAL_IN           NF_IP6_LOCAL_IN
  34 #define HOOK_FORWARD            NF_IP6_FORWARD
  35 #define HOOK_LOCAL_OUT          NF_IP6_LOCAL_OUT
  36 #define HOOK_POST_ROUTING       NF_IP6_POST_ROUTING
  37
  38 #define STRUCT_ENTRY_TARGET     struct xt_entry_target
  39 #define STRUCT_ENTRY            struct ip6t_entry
  40 #define STRUCT_ENTRY_MATCH      struct xt_entry_match
  41 #define STRUCT_GETINFO          struct ip6t_getinfo
  42 #define STRUCT_GET_ENTRIES      struct ip6t_get_entries
  43 #define STRUCT_COUNTERS         struct xt_counters
  44 #define STRUCT_COUNTERS_INFO    struct xt_counters_info
  45 #define STRUCT_STANDARD_TARGET  struct xt_standard_target
  46 #define STRUCT_REPLACE          struct ip6t_replace
  47
  48 #define ENTRY_ITERATE           IP6T_ENTRY_ITERATE
  49 #define TABLE_MAXNAMELEN        XT_TABLE_MAXNAMELEN
  50 #define FUNCTION_MAXNAMELEN     XT_FUNCTION_MAXNAMELEN
  51
  52 #define GET_TARGET              ip6t_get_target
  53
  54 #define ERROR_TARGET            XT_ERROR_TARGET
  55 #define NUMHOOKS                NF_IP6_NUMHOOKS
  56
  57 #define IPT_CHAINLABEL          xt_chainlabel
  58
  59 #define TC_DUMP_ENTRIES         dump_entries6
  60 #define TC_IS_CHAIN             ip6tc_is_chain
  61 #define TC_FIRST_CHAIN          ip6tc_first_chain
  62 #define TC_NEXT_CHAIN           ip6tc_next_chain
  63 #define TC_FIRST_RULE           ip6tc_first_rule
  64 #define TC_NEXT_RULE            ip6tc_next_rule
  65 #define TC_GET_TARGET           ip6tc_get_target
  66 #define TC_BUILTIN              ip6tc_builtin
  67 #define TC_GET_POLICY           ip6tc_get_policy
  68 #define TC_INSERT_ENTRY         ip6tc_insert_entry
  69 #define TC_REPLACE_ENTRY        ip6tc_replace_entry
  70 #define TC_APPEND_ENTRY         ip6tc_append_entry
  71 #define TC_CHECK_ENTRY          ip6tc_check_entry
  72 #define TC_DELETE_ENTRY         ip6tc_delete_entry
  73 #define TC_DELETE_NUM_ENTRY     ip6tc_delete_num_entry
  74 #define TC_FLUSH_ENTRIES        ip6tc_flush_entries
  75 #define TC_ZERO_ENTRIES         ip6tc_zero_entries
  76 #define TC_ZERO_COUNTER         ip6tc_zero_counter
  77 #define TC_READ_COUNTER         ip6tc_read_counter
  78 #define TC_SET_COUNTER          ip6tc_set_counter
  79 #define TC_CREATE_CHAIN         ip6tc_create_chain
  80 #define TC_GET_REFERENCES       ip6tc_get_references
  81 #define TC_DELETE_CHAIN         ip6tc_delete_chain
  82 #define TC_RENAME_CHAIN         ip6tc_rename_chain
  83 #define TC_SET_POLICY           ip6tc_set_policy
  84 #define TC_GET_RAW_SOCKET       ip6tc_get_raw_socket
  85 #define TC_INIT                 ip6tc_init
  86 #define TC_FREE                 ip6tc_free
  87 #define TC_COMMIT               ip6tc_commit
  88 #define TC_STRERROR             ip6tc_strerror
  89 #define TC_NUM_RULES            ip6tc_num_rules
  90 #define TC_GET_RULE             ip6tc_get_rule
  91 #define TC_OPS                  ip6tc_ops
  92
  93 #define TC_AF                   AF_INET6
  94 #define TC_IPPROTO              IPPROTO_IPV6
  95
  96 #define SO_SET_REPLACE          IP6T_SO_SET_REPLACE
  97 #define SO_SET_ADD_COUNTERS     IP6T_SO_SET_ADD_COUNTERS
  98 #define SO_GET_INFO             IP6T_SO_GET_INFO
  99 #define SO_GET_ENTRIES          IP6T_SO_GET_ENTRIES
 100 #define SO_GET_VERSION          IP6T_SO_GET_VERSION
 101
 102 #define STANDARD_TARGET         XT_STANDARD_TARGET
 103 #define LABEL_RETURN            IP6TC_LABEL_RETURN
 104 #define LABEL_ACCEPT            IP6TC_LABEL_ACCEPT
 105 #define LABEL_DROP              IP6TC_LABEL_DROP
 106 #define LABEL_QUEUE             IP6TC_LABEL_QUEUE
 107
 108 #define ALIGN                   XT_ALIGN
 109 #define RETURN                  XT_RETURN
 110
 111 #include "libiptc.c"
 112
 113 #define BIT6(a, l) \
 114  ((ntohl(a->s6_addr32[(l) / 32]) >> (31 - ((l) & 31))) & 1)
 115
 116 int
 117 ipv6_prefix_length(const struct in6_addr *a)
 118 {
 119         int l, i;
 120         for (l = 0; l < 128; l++) {
 121                 if (BIT6(a, l) == 0)
 122                         break;
 123         }
 124         for (i = l + 1; i < 128; i++) {
 125                 if (BIT6(a, i) == 1)
 126                         return -1;
 127         }
 128         return l;
 129 }
 130
 131 static int
 132 dump_entry(struct ip6t_entry *e, struct xtc_handle *const handle)
 133 {
 134         size_t i;
 135         char buf[40];
 136         int len;
 137         struct xt_entry_target *t;
 138
 139         printf("Entry %u (%lu):\n", iptcb_entry2index(handle, e),
 140                iptcb_entry2offset(handle, e));
 141         puts("SRC IP: ");
 142         inet_ntop(AF_INET6, &e->ipv6.src, buf, sizeof buf);
 143         puts(buf);
 144         putchar('/');
 145         len = ipv6_prefix_length(&e->ipv6.smsk);
 146         if (len != -1)
 147                 printf("%d", len);
 148         else {
 149                 inet_ntop(AF_INET6, &e->ipv6.smsk, buf, sizeof buf);
 150                 puts(buf);
 151         }
 152         putchar('\n');
 153
 154         puts("DST IP: ");
 155         inet_ntop(AF_INET6, &e->ipv6.dst, buf, sizeof buf);
 156         puts(buf);
 157         putchar('/');
 158         len = ipv6_prefix_length(&e->ipv6.dmsk);
 159         if (len != -1)
 160                 printf("%d", len);
 161         else {
 162                 inet_ntop(AF_INET6, &e->ipv6.dmsk, buf, sizeof buf);
 163                 puts(buf);
 164         }
 165         putchar('\n');
 166
 167         printf("Interface: `%s'/", e->ipv6.iniface);
 168         for (i = 0; i < IFNAMSIZ; i++)
 169                 printf("%c", e->ipv6.iniface_mask[i] ? 'X' : '.');
 170         printf("to `%s'/", e->ipv6.outiface);
 171         for (i = 0; i < IFNAMSIZ; i++)
 172                 printf("%c", e->ipv6.outiface_mask[i] ? 'X' : '.');
 173         printf("\nProtocol: %u\n", e->ipv6.proto);
 174         if (e->ipv6.flags & IP6T_F_TOS)
 175                 printf("TOS: %u\n", e->ipv6.tos);
 176         printf("Flags: %02X\n", e->ipv6.flags);
 177         printf("Invflags: %02X\n", e->ipv6.invflags);
 178         printf("Counters: %llu packets, %llu bytes\n",
 179                (unsigned long long)e->counters.pcnt, (unsigned long long)e->counters.bcnt);
 180         printf("Cache: %08X\n", e->nfcache);
 181
 182         IP6T_MATCH_ITERATE(e, print_match);
 183
 184         t = ip6t_get_target(e);
 185         printf("Target name: `%s' [%u]\n", t->u.user.name, t->u.target_size);
 186         if (strcmp(t->u.user.name, XT_STANDARD_TARGET) == 0) {
 187                 const unsigned char *data = t->data;
 188                 int pos = *(const int *)data;
 189                 if (pos < 0)
 190                         printf("verdict=%s\n",
 191                                pos == -NF_ACCEPT-1 ? "NF_ACCEPT"
 192                                : pos == -NF_DROP-1 ? "NF_DROP"
 193                                : pos == XT_RETURN ? "RETURN"
 194                                : "UNKNOWN");
 195                 else
 196                         printf("verdict=%u\n", pos);
 197         } else if (strcmp(t->u.user.name, XT_ERROR_TARGET) == 0)
 198                 printf("error=`%s'\n", t->data);
 199
 200         printf("\n");
 201         return 0;
 202 }
 203
 204 static unsigned char *
 205 is_same(const STRUCT_ENTRY *a, const STRUCT_ENTRY *b,
 206         unsigned char *matchmask)
 207 {
 208         unsigned int i;
 209         unsigned char *mptr;
 210
 211         /* Always compare head structures: ignore mask here. */
 212         if (memcmp(&a->ipv6.src, &b->ipv6.src, sizeof(struct in6_addr))
 213             || memcmp(&a->ipv6.dst, &b->ipv6.dst, sizeof(struct in6_addr))
 214             || memcmp(&a->ipv6.smsk, &b->ipv6.smsk, sizeof(struct in6_addr))
 215             || memcmp(&a->ipv6.dmsk, &b->ipv6.dmsk, sizeof(struct in6_addr))
 216             || a->ipv6.proto != b->ipv6.proto
 217             || a->ipv6.tos != b->ipv6.tos
 218             || a->ipv6.flags != b->ipv6.flags
 219             || a->ipv6.invflags != b->ipv6.invflags)
 220                 return NULL;
 221
 222         for (i = 0; i < IFNAMSIZ; i++) {
 223                 if (a->ipv6.iniface_mask[i] != b->ipv6.iniface_mask[i])
 224                         return NULL;
 225                 if ((a->ipv6.iniface[i] & a->ipv6.iniface_mask[i])
 226                     != (b->ipv6.iniface[i] & b->ipv6.iniface_mask[i]))
 227                         return NULL;
 228                 if (a->ipv6.outiface_mask[i] != b->ipv6.outiface_mask[i])
 229                         return NULL;
 230                 if ((a->ipv6.outiface[i] & a->ipv6.outiface_mask[i])
 231                     != (b->ipv6.outiface[i] & b->ipv6.outiface_mask[i]))
 232                         return NULL;
 233         }
 234
 235         if (a->target_offset != b->target_offset
 236             || a->next_offset != b->next_offset)
 237                 return NULL;
 238
 239         mptr = matchmask + sizeof(STRUCT_ENTRY);
 240         if (IP6T_MATCH_ITERATE(a, match_different, a->elems, b->elems, &mptr))
 241                 return NULL;
 242         mptr += XT_ALIGN(sizeof(struct xt_entry_target));
 243
 244         return mptr;
 245 }
 246
 247 /* All zeroes == unconditional rule. */
 248 static inline int
 249 unconditional(const struct ip6t_ip6 *ipv6)
 250 {
 251         unsigned int i;
 252
 253         for (i = 0; i < sizeof(*ipv6); i++)
 254                 if (((char *)ipv6)[i])
 255                         break;
 256
 257         return (i == sizeof(*ipv6));
 258 }
 259
 260 #ifdef IPTC_DEBUG
 261 /* Do every conceivable sanity check on the handle */
 262 static void
 263 do_check(struct xtc_handle *h, unsigned int line)
 264 {
 265         unsigned int i, n;
 266         unsigned int user_offset; /* Offset of first user chain */
 267         int was_return;
 268
 269         assert(h->changed == 0 || h->changed == 1);
 270         if (strcmp(h->info.name, "filter") == 0) {
 271                 assert(h->info.valid_hooks
 272                        == (1 << NF_IP6_LOCAL_IN
 273                            | 1 << NF_IP6_FORWARD
 274                            | 1 << NF_IP6_LOCAL_OUT));
 275
 276                 /* Hooks should be first three */
 277                 assert(h->info.hook_entry[NF_IP6_LOCAL_IN] == 0);
 278
 279                 n = get_chain_end(h, 0);
 280                 n += get_entry(h, n)->next_offset;
 281                 assert(h->info.hook_entry[NF_IP6_FORWARD] == n);
 282
 283                 n = get_chain_end(h, n);
 284                 n += get_entry(h, n)->next_offset;
 285                 assert(h->info.hook_entry[NF_IP6_LOCAL_OUT] == n);
 286
 287                 user_offset = h->info.hook_entry[NF_IP6_LOCAL_OUT];
 288         } else if (strcmp(h->info.name, "nat") == 0) {
 289                 assert((h->info.valid_hooks
 290                         == (1 << NF_IP6_PRE_ROUTING
 291                             | 1 << NF_IP6_LOCAL_OUT
 292                             | 1 << NF_IP6_POST_ROUTING)) ||
 293                        (h->info.valid_hooks
 294                         == (1 << NF_IP6_PRE_ROUTING
 295                             | 1 << NF_IP6_LOCAL_IN
 296                             | 1 << NF_IP6_LOCAL_OUT
 297                             | 1 << NF_IP6_POST_ROUTING)));
 298
 299                 assert(h->info.hook_entry[NF_IP6_PRE_ROUTING] == 0);
 300
 301                 n = get_chain_end(h, 0);
 302
 303                 n += get_entry(h, n)->next_offset;
 304                 assert(h->info.hook_entry[NF_IP6_POST_ROUTING] == n);
 305                 n = get_chain_end(h, n);
 306
 307                 n += get_entry(h, n)->next_offset;
 308                 assert(h->info.hook_entry[NF_IP6_LOCAL_OUT] == n);
 309                 user_offset = h->info.hook_entry[NF_IP6_LOCAL_OUT];
 310
 311                 if (h->info.valid_hooks & (1 << NF_IP6_LOCAL_IN)) {
 312                         n = get_chain_end(h, n);
 313                         n += get_entry(h, n)->next_offset;
 314                         assert(h->info.hook_entry[NF_IP6_LOCAL_IN] == n);
 315                         user_offset = h->info.hook_entry[NF_IP6_LOCAL_IN];
 316                 }
 317
 318         } else if (strcmp(h->info.name, "mangle") == 0) {
 319                 /* This code is getting ugly because linux < 2.4.18-pre6 had
 320                  * two mangle hooks, linux >= 2.4.18-pre6 has five mangle hooks
 321                  * */
 322                 assert((h->info.valid_hooks
 323                         == (1 << NF_IP6_PRE_ROUTING
 324                             | 1 << NF_IP6_LOCAL_OUT)) ||
 325                        (h->info.valid_hooks
 326                         == (1 << NF_IP6_PRE_ROUTING
 327                             | 1 << NF_IP6_LOCAL_IN
 328                             | 1 << NF_IP6_FORWARD
 329                             | 1 << NF_IP6_LOCAL_OUT
 330                             | 1 << NF_IP6_POST_ROUTING)));
 331
 332                 /* Hooks should be first five */
 333                 assert(h->info.hook_entry[NF_IP6_PRE_ROUTING] == 0);
 334
 335                 n = get_chain_end(h, 0);
 336
 337                 if (h->info.valid_hooks & (1 << NF_IP6_LOCAL_IN)) {
 338                         n += get_entry(h, n)->next_offset;
 339                         assert(h->info.hook_entry[NF_IP6_LOCAL_IN] == n);
 340                         n = get_chain_end(h, n);
 341                 }
 342
 343                 if (h->info.valid_hooks & (1 << NF_IP6_FORWARD)) {
 344                         n += get_entry(h, n)->next_offset;
 345                         assert(h->info.hook_entry[NF_IP6_FORWARD] == n);
 346                         n = get_chain_end(h, n);
 347                 }
 348
 349                 n += get_entry(h, n)->next_offset;
 350                 assert(h->info.hook_entry[NF_IP6_LOCAL_OUT] == n);
 351                 user_offset = h->info.hook_entry[NF_IP6_LOCAL_OUT];
 352
 353                 if (h->info.valid_hooks & (1 << NF_IP6_POST_ROUTING)) {
 354                         n = get_chain_end(h, n);
 355                         n += get_entry(h, n)->next_offset;
 356                         assert(h->info.hook_entry[NF_IP6_POST_ROUTING] == n);
 357                         user_offset = h->info.hook_entry[NF_IP6_POST_ROUTING];
 358                 }
 359         } else if (strcmp(h->info.name, "raw") == 0) {
 360                 assert(h->info.valid_hooks
 361                        == (1 << NF_IP6_PRE_ROUTING
 362                            | 1 << NF_IP6_LOCAL_OUT));
 363
 364                 /* Hooks should be first three */
 365                 assert(h->info.hook_entry[NF_IP6_PRE_ROUTING] == 0);
 366
 367                 n = get_chain_end(h, n);
 368                 n += get_entry(h, n)->next_offset;
 369                 assert(h->info.hook_entry[NF_IP6_LOCAL_OUT] == n);
 370
 371                 user_offset = h->info.hook_entry[NF_IP6_LOCAL_OUT];
 372         } else {
 373                 fprintf(stderr, "Unknown table `%s'\n", h->info.name);
 374                 abort();
 375         }
 376
 377         /* User chain == end of last builtin + policy entry */
 378         user_offset = get_chain_end(h, user_offset);
 379         user_offset += get_entry(h, user_offset)->next_offset;
 380
 381         /* Overflows should be end of entry chains, and unconditional
 382            policy nodes. */
 383         for (i = 0; i < NUMHOOKS; i++) {
 384                 STRUCT_ENTRY *e;
 385                 STRUCT_STANDARD_TARGET *t;
 386
 387                 if (!(h->info.valid_hooks & (1 << i)))
 388                         continue;
 389                 assert(h->info.underflow[i]
 390                        == get_chain_end(h, h->info.hook_entry[i]));
 391
 392                 e = get_entry(h, get_chain_end(h, h->info.hook_entry[i]));
 393                 assert(unconditional(&e->ipv6));
 394                 assert(e->target_offset == sizeof(*e));
 395                 t = (STRUCT_STANDARD_TARGET *)GET_TARGET(e);
 396                 printf("target_size=%u, align=%u\n",
 397                         t->target.u.target_size, ALIGN(sizeof(*t)));
 398                 assert(t->target.u.target_size == ALIGN(sizeof(*t)));
 399                 assert(e->next_offset == sizeof(*e) + ALIGN(sizeof(*t)));
 400
 401                 assert(strcmp(t->target.u.user.name, STANDARD_TARGET)==0);
 402                 assert(t->verdict == -NF_DROP-1 || t->verdict == -NF_ACCEPT-1);
 403
 404                 /* Hooks and underflows must be valid entries */
 405                 iptcb_entry2index(h, get_entry(h, h->info.hook_entry[i]));
 406                 iptcb_entry2index(h, get_entry(h, h->info.underflow[i]));
 407         }
 408
 409         assert(h->info.size
 410                >= h->info.num_entries * (sizeof(STRUCT_ENTRY)
 411                                          +sizeof(STRUCT_STANDARD_TARGET)));
 412
 413         assert(h->entries.size
 414                >= (h->new_number
 415                    * (sizeof(STRUCT_ENTRY)
 416                       + sizeof(STRUCT_STANDARD_TARGET))));
 417         assert(strcmp(h->info.name, h->entries.name) == 0);
 418
 419         i = 0; n = 0;
 420         was_return = 0;
 421
 422 #if 0
 423         /* Check all the entries. */
 424         ENTRY_ITERATE(h->entries.entrytable, h->entries.size,
 425                       check_entry, &i, &n, user_offset, &was_return, h);
 426
 427         assert(i == h->new_number);
 428         assert(n == h->entries.size);
 429
 430         /* Final entry must be error node */
 431         assert(strcmp(GET_TARGET(index2entry(h, h->new_number-1))
 432                       ->u.user.name,
 433                       ERROR_TARGET) == 0);
 434 #endif
 435 }
 436 #endif /*IPTC_DEBUG*/