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 ip6t_entry_target
  39 #define STRUCT_ENTRY            struct ip6t_entry
  40 #define STRUCT_ENTRY_MATCH      struct ip6t_entry_match
  41 #define STRUCT_GETINFO          struct ip6t_getinfo
  42 #define STRUCT_GET_ENTRIES      struct ip6t_get_entries
  43 #define STRUCT_COUNTERS         struct ip6t_counters
  44 #define STRUCT_COUNTERS_INFO    struct ip6t_counters_info
  45 #define STRUCT_STANDARD_TARGET  struct ip6t_standard_target
  46 #define STRUCT_REPLACE          struct ip6t_replace
  47
  48 #define STRUCT_TC_HANDLE        struct ip6tc_handle
  49 #define TC_HANDLE_T             ip6tc_handle_t
  50
  51 #define ENTRY_ITERATE           IP6T_ENTRY_ITERATE
  52 #define TABLE_MAXNAMELEN        IP6T_TABLE_MAXNAMELEN
  53 #define FUNCTION_MAXNAMELEN     IP6T_FUNCTION_MAXNAMELEN
  54
  55 #define GET_TARGET              ip6t_get_target
  56
  57 #define ERROR_TARGET            IP6T_ERROR_TARGET
  58 #define NUMHOOKS                NF_IP6_NUMHOOKS
  59
  60 #define IPT_CHAINLABEL          ip6t_chainlabel
  61
  62 #define TC_DUMP_ENTRIES         dump_entries6
  63 #define TC_IS_CHAIN             ip6tc_is_chain
  64 #define TC_FIRST_CHAIN          ip6tc_first_chain
  65 #define TC_NEXT_CHAIN           ip6tc_next_chain
  66 #define TC_FIRST_RULE           ip6tc_first_rule
  67 #define TC_NEXT_RULE            ip6tc_next_rule
  68 #define TC_GET_TARGET           ip6tc_get_target
  69 #define TC_BUILTIN              ip6tc_builtin
  70 #define TC_GET_POLICY           ip6tc_get_policy
  71 #define TC_INSERT_ENTRY         ip6tc_insert_entry
  72 #define TC_REPLACE_ENTRY        ip6tc_replace_entry
  73 #define TC_APPEND_ENTRY         ip6tc_append_entry
  74 #define TC_DELETE_ENTRY         ip6tc_delete_entry
  75 #define TC_DELETE_NUM_ENTRY     ip6tc_delete_num_entry
  76 #define TC_CHECK_PACKET         ip6tc_check_packet
  77 #define TC_FLUSH_ENTRIES        ip6tc_flush_entries
  78 #define TC_ZERO_ENTRIES         ip6tc_zero_entries
  79 #define TC_ZERO_COUNTER         ip6tc_zero_counter
  80 #define TC_READ_COUNTER         ip6tc_read_counter
  81 #define TC_SET_COUNTER          ip6tc_set_counter
  82 #define TC_CREATE_CHAIN         ip6tc_create_chain
  83 #define TC_GET_REFERENCES       ip6tc_get_references
  84 #define TC_DELETE_CHAIN         ip6tc_delete_chain
  85 #define TC_RENAME_CHAIN         ip6tc_rename_chain
  86 #define TC_SET_POLICY           ip6tc_set_policy
  87 #define TC_GET_RAW_SOCKET       ip6tc_get_raw_socket
  88 #define TC_INIT                 ip6tc_init
  89 #define TC_FREE                 ip6tc_free
  90 #define TC_COMMIT               ip6tc_commit
  91 #define TC_STRERROR             ip6tc_strerror
  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         IP6T_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                   IP6T_ALIGN
 109 #define RETURN                  IP6T_RETURN
 110
 111 #include "libiptc.c"
 112
 113 #define BIT6(a, l) \
 114  ((ntohl(a->in6_u.u6_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, const ip6tc_handle_t handle)
 133 {
 134         size_t i;
 135         char buf[40];
 136         int len;
 137         struct ip6t_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 ", e->nfcache);
 181         if (e->nfcache & NFC_ALTERED) printf("ALTERED ");
 182         if (e->nfcache & NFC_UNKNOWN) printf("UNKNOWN ");
 183         printf("\n");
 184
 185         IP6T_MATCH_ITERATE(e, print_match);
 186
 187         t = ip6t_get_target(e);
 188         printf("Target name: `%s' [%u]\n", t->u.user.name, t->u.target_size);
 189         if (strcmp(t->u.user.name, IP6T_STANDARD_TARGET) == 0) {
 190                 int pos = *(int *)t->data;
 191                 if (pos < 0)
 192                         printf("verdict=%s\n",
 193                                pos == -NF_ACCEPT-1 ? "NF_ACCEPT"
 194                                : pos == -NF_DROP-1 ? "NF_DROP"
 195                                : pos == IP6T_RETURN ? "RETURN"
 196                                : "UNKNOWN");
 197                 else
 198                         printf("verdict=%u\n", pos);
 199         } else if (strcmp(t->u.user.name, IP6T_ERROR_TARGET) == 0)
 200                 printf("error=`%s'\n", t->data);
 201
 202         printf("\n");
 203         return 0;
 204 }
 205
 206 static unsigned char *
 207 is_same(const STRUCT_ENTRY *a, const STRUCT_ENTRY *b,
 208         unsigned char *matchmask)
 209 {
 210         unsigned int i;
 211         unsigned char *mptr;
 212
 213         /* Always compare head structures: ignore mask here. */
 214         if (memcmp(&a->ipv6.src, &b->ipv6.src, sizeof(struct in6_addr))
 215             || memcmp(&a->ipv6.dst, &b->ipv6.dst, sizeof(struct in6_addr))
 216             || memcmp(&a->ipv6.smsk, &b->ipv6.smsk, sizeof(struct in6_addr))
 217             || memcmp(&a->ipv6.dmsk, &b->ipv6.dmsk, sizeof(struct in6_addr))
 218             || a->ipv6.proto != b->ipv6.proto
 219             || a->ipv6.tos != b->ipv6.tos
 220             || a->ipv6.flags != b->ipv6.flags
 221             || a->ipv6.invflags != b->ipv6.invflags)
 222                 return NULL;
 223
 224         for (i = 0; i < IFNAMSIZ; i++) {
 225                 if (a->ipv6.iniface_mask[i] != b->ipv6.iniface_mask[i])
 226                         return NULL;
 227                 if ((a->ipv6.iniface[i] & a->ipv6.iniface_mask[i])
 228                     != (b->ipv6.iniface[i] & b->ipv6.iniface_mask[i]))
 229                         return NULL;
 230                 if (a->ipv6.outiface_mask[i] != b->ipv6.outiface_mask[i])
 231                         return NULL;
 232                 if ((a->ipv6.outiface[i] & a->ipv6.outiface_mask[i])
 233                     != (b->ipv6.outiface[i] & b->ipv6.outiface_mask[i]))
 234                         return NULL;
 235         }
 236
 237         if (a->nfcache != b->nfcache
 238             || a->target_offset != b->target_offset
 239             || a->next_offset != b->next_offset)
 240                 return NULL;
 241
 242         mptr = matchmask + sizeof(STRUCT_ENTRY);
 243         if (IP6T_MATCH_ITERATE(a, match_different, a->elems, b->elems, &mptr))
 244                 return NULL;
 245         mptr += IP6T_ALIGN(sizeof(struct ip6t_entry_target));
 246
 247         return mptr;
 248 }
 249
 250 /* All zeroes == unconditional rule. */
 251 static inline int
 252 unconditional(const struct ip6t_ip6 *ipv6)
 253 {
 254         unsigned int i;
 255
 256         for (i = 0; i < sizeof(*ipv6); i++)
 257                 if (((char *)ipv6)[i])
 258                         break;
 259
 260         return (i == sizeof(*ipv6));
 261 }
 262
 263 #ifdef IPTC_DEBUG
 264 /* Do every conceivable sanity check on the handle */
 265 static void
 266 do_check(TC_HANDLE_T h, unsigned int line)
 267 {
 268         unsigned int i, n;
 269         unsigned int user_offset; /* Offset of first user chain */
 270         int was_return;
 271
 272         assert(h->changed == 0 || h->changed == 1);
 273         if (strcmp(h->info.name, "filter") == 0) {
 274                 assert(h->info.valid_hooks
 275                        == (1 << NF_IP6_LOCAL_IN
 276                            | 1 << NF_IP6_FORWARD
 277                            | 1 << NF_IP6_LOCAL_OUT));
 278
 279                 /* Hooks should be first three */
 280                 assert(h->info.hook_entry[NF_IP6_LOCAL_IN] == 0);
 281
 282                 n = get_chain_end(h, 0);
 283                 n += get_entry(h, n)->next_offset;
 284                 assert(h->info.hook_entry[NF_IP6_FORWARD] == n);
 285
 286                 n = get_chain_end(h, n);
 287                 n += get_entry(h, n)->next_offset;
 288                 assert(h->info.hook_entry[NF_IP6_LOCAL_OUT] == n);
 289
 290                 user_offset = h->info.hook_entry[NF_IP6_LOCAL_OUT];
 291         } else if (strcmp(h->info.name, "nat") == 0) {
 292                 assert((h->info.valid_hooks
 293                         == (1 << NF_IP6_PRE_ROUTING
 294                             | 1 << NF_IP6_LOCAL_OUT
 295                             | 1 << NF_IP6_POST_ROUTING)) ||
 296                        (h->info.valid_hooks
 297                         == (1 << NF_IP6_PRE_ROUTING
 298                             | 1 << NF_IP6_LOCAL_IN
 299                             | 1 << NF_IP6_LOCAL_OUT
 300                             | 1 << NF_IP6_POST_ROUTING)));
 301
 302                 assert(h->info.hook_entry[NF_IP6_PRE_ROUTING] == 0);
 303
 304                 n = get_chain_end(h, 0);
 305
 306                 n += get_entry(h, n)->next_offset;
 307                 assert(h->info.hook_entry[NF_IP6_POST_ROUTING] == n);
 308                 n = get_chain_end(h, n);
 309
 310                 n += get_entry(h, n)->next_offset;
 311                 assert(h->info.hook_entry[NF_IP6_LOCAL_OUT] == n);
 312                 user_offset = h->info.hook_entry[NF_IP6_LOCAL_OUT];
 313
 314                 if (h->info.valid_hooks & (1 << NF_IP6_LOCAL_IN)) {
 315                         n = get_chain_end(h, n);
 316                         n += get_entry(h, n)->next_offset;
 317                         assert(h->info.hook_entry[NF_IP6_LOCAL_IN] == n);
 318                         user_offset = h->info.hook_entry[NF_IP6_LOCAL_IN];
 319                 }
 320
 321         } else if (strcmp(h->info.name, "mangle") == 0) {
 322                 /* This code is getting ugly because linux < 2.4.18-pre6 had
 323                  * two mangle hooks, linux >= 2.4.18-pre6 has five mangle hooks
 324                  * */
 325                 assert((h->info.valid_hooks
 326                         == (1 << NF_IP6_PRE_ROUTING
 327                             | 1 << NF_IP6_LOCAL_OUT)) ||
 328                        (h->info.valid_hooks
 329                         == (1 << NF_IP6_PRE_ROUTING
 330                             | 1 << NF_IP6_LOCAL_IN
 331                             | 1 << NF_IP6_FORWARD
 332                             | 1 << NF_IP6_LOCAL_OUT
 333                             | 1 << NF_IP6_POST_ROUTING)));
 334
 335                 /* Hooks should be first five */
 336                 assert(h->info.hook_entry[NF_IP6_PRE_ROUTING] == 0);
 337
 338                 n = get_chain_end(h, 0);
 339
 340                 if (h->info.valid_hooks & (1 << NF_IP6_LOCAL_IN)) {
 341                         n += get_entry(h, n)->next_offset;
 342                         assert(h->info.hook_entry[NF_IP6_LOCAL_IN] == n);
 343                         n = get_chain_end(h, n);
 344                 }
 345
 346                 if (h->info.valid_hooks & (1 << NF_IP6_FORWARD)) {
 347                         n += get_entry(h, n)->next_offset;
 348                         assert(h->info.hook_entry[NF_IP6_FORWARD] == n);
 349                         n = get_chain_end(h, n);
 350                 }
 351
 352                 n += get_entry(h, n)->next_offset;
 353                 assert(h->info.hook_entry[NF_IP6_LOCAL_OUT] == n);
 354                 user_offset = h->info.hook_entry[NF_IP6_LOCAL_OUT];
 355
 356                 if (h->info.valid_hooks & (1 << NF_IP6_POST_ROUTING)) {
 357                         n = get_chain_end(h, n);
 358                         n += get_entry(h, n)->next_offset;
 359                         assert(h->info.hook_entry[NF_IP6_POST_ROUTING] == n);
 360                         user_offset = h->info.hook_entry[NF_IP6_POST_ROUTING];
 361                 }
 362         } else if (strcmp(h->info.name, "raw") == 0) {
 363                 assert(h->info.valid_hooks
 364                        == (1 << NF_IP6_PRE_ROUTING
 365                            | 1 << NF_IP6_LOCAL_OUT));
 366
 367                 /* Hooks should be first three */
 368                 assert(h->info.hook_entry[NF_IP6_PRE_ROUTING] == 0);
 369
 370                 n = get_chain_end(h, n);
 371                 n += get_entry(h, n)->next_offset;
 372                 assert(h->info.hook_entry[NF_IP6_LOCAL_OUT] == n);
 373
 374                 user_offset = h->info.hook_entry[NF_IP6_LOCAL_OUT];
 375         } else {
 376                 fprintf(stderr, "Unknown table `%s'\n", h->info.name);
 377                 abort();
 378         }
 379
 380         /* User chain == end of last builtin + policy entry */
 381         user_offset = get_chain_end(h, user_offset);
 382         user_offset += get_entry(h, user_offset)->next_offset;
 383
 384         /* Overflows should be end of entry chains, and unconditional
 385            policy nodes. */
 386         for (i = 0; i < NUMHOOKS; i++) {
 387                 STRUCT_ENTRY *e;
 388                 STRUCT_STANDARD_TARGET *t;
 389
 390                 if (!(h->info.valid_hooks & (1 << i)))
 391                         continue;
 392                 assert(h->info.underflow[i]
 393                        == get_chain_end(h, h->info.hook_entry[i]));
 394
 395                 e = get_entry(h, get_chain_end(h, h->info.hook_entry[i]));
 396                 assert(unconditional(&e->ipv6));
 397                 assert(e->target_offset == sizeof(*e));
 398                 t = (STRUCT_STANDARD_TARGET *)GET_TARGET(e);
 399                 printf("target_size=%u, align=%u\n",
 400                         t->target.u.target_size, ALIGN(sizeof(*t)));
 401                 assert(t->target.u.target_size == ALIGN(sizeof(*t)));
 402                 assert(e->next_offset == sizeof(*e) + ALIGN(sizeof(*t)));
 403
 404                 assert(strcmp(t->target.u.user.name, STANDARD_TARGET)==0);
 405                 assert(t->verdict == -NF_DROP-1 || t->verdict == -NF_ACCEPT-1);
 406
 407                 /* Hooks and underflows must be valid entries */
 408                 iptcb_entry2index(h, get_entry(h, h->info.hook_entry[i]));
 409                 iptcb_entry2index(h, get_entry(h, h->info.underflow[i]));
 410         }
 411
 412         assert(h->info.size
 413                >= h->info.num_entries * (sizeof(STRUCT_ENTRY)
 414                                          +sizeof(STRUCT_STANDARD_TARGET)));
 415
 416         assert(h->entries.size
 417                >= (h->new_number
 418                    * (sizeof(STRUCT_ENTRY)
 419                       + sizeof(STRUCT_STANDARD_TARGET))));
 420         assert(strcmp(h->info.name, h->entries.name) == 0);
 421
 422         i = 0; n = 0;
 423         was_return = 0;
 424
 425 #if 0
 426         /* Check all the entries. */
 427         ENTRY_ITERATE(h->entries.entrytable, h->entries.size,
 428                       check_entry, &i, &n, user_offset, &was_return, h);
 429
 430         assert(i == h->new_number);
 431         assert(n == h->entries.size);
 432
 433         /* Final entry must be error node */
 434         assert(strcmp(GET_TARGET(index2entry(h, h->new_number-1))
 435                       ->u.user.name,
 436                       ERROR_TARGET) == 0);
 437 #endif
 438 }
 439 #endif /*IPTC_DEBUG*/