libiptc2/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", entry2index(handle, e),
 140                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                e->counters.pcnt, 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         if (e->nfcache & NFC_IP6_SRC) printf("IP6_SRC ");
 184         if (e->nfcache & NFC_IP6_DST) printf("IP6_DST ");
 185         if (e->nfcache & NFC_IP6_IF_IN) printf("IP6_IF_IN ");
 186         if (e->nfcache & NFC_IP6_IF_OUT) printf("IP6_IF_OUT ");
 187         if (e->nfcache & NFC_IP6_TOS) printf("IP6_TOS ");
 188         if (e->nfcache & NFC_IP6_PROTO) printf("IP6_PROTO ");
 189         if (e->nfcache & NFC_IP6_OPTIONS) printf("IP6_OPTIONS ");
 190         if (e->nfcache & NFC_IP6_TCPFLAGS) printf("IP6_TCPFLAGS ");
 191         if (e->nfcache & NFC_IP6_SRC_PT) printf("IP6_SRC_PT ");
 192         if (e->nfcache & NFC_IP6_DST_PT) printf("IP6_DST_PT ");
 193         if (e->nfcache & NFC_IP6_PROTO_UNKNOWN) printf("IP6_PROTO_UNKNOWN ");
 194         printf("\n");
 195
 196         IP6T_MATCH_ITERATE(e, print_match);
 197
 198         t = ip6t_get_target(e);
 199         printf("Target name: `%s' [%u]\n", t->u.user.name, t->u.target_size);
 200         if (strcmp(t->u.user.name, IP6T_STANDARD_TARGET) == 0) {
 201                 int pos = *(int *)t->data;
 202                 if (pos < 0)
 203                         printf("verdict=%s\n",
 204                                pos == -NF_ACCEPT-1 ? "NF_ACCEPT"
 205                                : pos == -NF_DROP-1 ? "NF_DROP"
 206                                : pos == IP6T_RETURN ? "RETURN"
 207                                : "UNKNOWN");
 208                 else
 209                         printf("verdict=%u\n", pos);
 210         } else if (strcmp(t->u.user.name, IP6T_ERROR_TARGET) == 0)
 211                 printf("error=`%s'\n", t->data);
 212
 213         printf("\n");
 214         return 0;
 215 }
 216
 217 static int
 218 is_same(const STRUCT_ENTRY *a, const STRUCT_ENTRY *b,
 219         unsigned char *matchmask)
 220 {
 221         unsigned int i;
 222         STRUCT_ENTRY_TARGET *ta, *tb;
 223         unsigned char *mptr;
 224
 225         /* Always compare head structures: ignore mask here. */
 226         if (memcmp(&a->ipv6.src, &b->ipv6.src, sizeof(struct in6_addr))
 227             || memcmp(&a->ipv6.dst, &b->ipv6.dst, sizeof(struct in6_addr))
 228             || memcmp(&a->ipv6.smsk, &b->ipv6.smsk, sizeof(struct in6_addr))
 229             || memcmp(&a->ipv6.dmsk, &b->ipv6.dmsk, sizeof(struct in6_addr))
 230             || a->ipv6.proto != b->ipv6.proto
 231             || a->ipv6.tos != b->ipv6.tos
 232             || a->ipv6.flags != b->ipv6.flags
 233             || a->ipv6.invflags != b->ipv6.invflags)
 234                 return 0;
 235
 236         for (i = 0; i < IFNAMSIZ; i++) {
 237                 if (a->ipv6.iniface_mask[i] != b->ipv6.iniface_mask[i])
 238                         return 0;
 239                 if ((a->ipv6.iniface[i] & a->ipv6.iniface_mask[i])
 240                     != (b->ipv6.iniface[i] & b->ipv6.iniface_mask[i]))
 241                         return 0;
 242                 if (a->ipv6.outiface_mask[i] != b->ipv6.outiface_mask[i])
 243                         return 0;
 244                 if ((a->ipv6.outiface[i] & a->ipv6.outiface_mask[i])
 245                     != (b->ipv6.outiface[i] & b->ipv6.outiface_mask[i]))
 246                         return 0;
 247         }
 248
 249         if (a->nfcache != b->nfcache
 250             || a->target_offset != b->target_offset
 251             || a->next_offset != b->next_offset)
 252                 return 0;
 253
 254         mptr = matchmask + sizeof(STRUCT_ENTRY);
 255         if (IP6T_MATCH_ITERATE(a, match_different, a->elems, b->elems, &mptr))
 256                 return 0;
 257
 258         ta = GET_TARGET((STRUCT_ENTRY *)a);
 259         tb = GET_TARGET((STRUCT_ENTRY *)b);
 260         if (ta->u.target_size != tb->u.target_size)
 261                 return 0;
 262         if (strcmp(ta->u.user.name, tb->u.user.name) != 0)
 263                 return 0;
 264         mptr += sizeof(*ta);
 265
 266         if (target_different(ta->data, tb->data,
 267                              ta->u.target_size - sizeof(*ta), mptr))
 268                 return 0;
 269
 270         return 1;
 271 }
 272
 273 /* All zeroes == unconditional rule. */
 274 static inline int
 275 unconditional(const struct ip6t_ip6 *ipv6)
 276 {
 277         unsigned int i;
 278
 279         for (i = 0; i < sizeof(*ipv6); i++)
 280                 if (((char *)ipv6)[i])
 281                         break;
 282
 283         return (i == sizeof(*ipv6));
 284 }
 285
 286 #ifdef IPTC_DEBUG
 287 /* Do every conceivable sanity check on the handle */
 288 static void
 289 do_check(TC_HANDLE_T h, unsigned int line)
 290 {
 291         unsigned int i, n;
 292         unsigned int user_offset; /* Offset of first user chain */
 293         int was_return;
 294
 295         assert(h->changed == 0 || h->changed == 1);
 296         if (strcmp(h->info.name, "filter") == 0) {
 297                 assert(h->info.valid_hooks
 298                        == (1 << NF_IP6_LOCAL_IN
 299                            | 1 << NF_IP6_FORWARD
 300                            | 1 << NF_IP6_LOCAL_OUT));
 301
 302                 /* Hooks should be first three */
 303                 assert(h->info.hook_entry[NF_IP6_LOCAL_IN] == 0);
 304
 305                 n = get_chain_end(h, 0);
 306                 n += get_entry(h, n)->next_offset;
 307                 assert(h->info.hook_entry[NF_IP6_FORWARD] == n);
 308
 309                 n = get_chain_end(h, n);
 310                 n += get_entry(h, n)->next_offset;
 311                 assert(h->info.hook_entry[NF_IP6_LOCAL_OUT] == n);
 312
 313                 user_offset = h->info.hook_entry[NF_IP6_LOCAL_OUT];
 314         } else if (strcmp(h->info.name, "nat") == 0) {
 315                 assert((h->info.valid_hooks
 316                         == (1 << NF_IP6_PRE_ROUTING
 317                             | 1 << NF_IP6_LOCAL_OUT
 318                             | 1 << NF_IP6_POST_ROUTING)) ||
 319                        (h->info.valid_hooks
 320                         == (1 << NF_IP6_PRE_ROUTING
 321                             | 1 << NF_IP6_LOCAL_IN
 322                             | 1 << NF_IP6_LOCAL_OUT
 323                             | 1 << NF_IP6_POST_ROUTING)));
 324
 325                 assert(h->info.hook_entry[NF_IP6_PRE_ROUTING] == 0);
 326
 327                 n = get_chain_end(h, 0);
 328
 329                 n += get_entry(h, n)->next_offset;
 330                 assert(h->info.hook_entry[NF_IP6_POST_ROUTING] == n);
 331                 n = get_chain_end(h, n);
 332
 333                 n += get_entry(h, n)->next_offset;
 334                 assert(h->info.hook_entry[NF_IP6_LOCAL_OUT] == n);
 335                 user_offset = h->info.hook_entry[NF_IP6_LOCAL_OUT];
 336
 337                 if (h->info.valid_hooks & (1 << NF_IP6_LOCAL_IN)) {
 338                         n = get_chain_end(h, n);
 339                         n += get_entry(h, n)->next_offset;
 340                         assert(h->info.hook_entry[NF_IP6_LOCAL_IN] == n);
 341                         user_offset = h->info.hook_entry[NF_IP6_LOCAL_IN];
 342                 }
 343
 344         } else if (strcmp(h->info.name, "mangle") == 0) {
 345                 /* This code is getting ugly because linux < 2.4.18-pre6 had
 346                  * two mangle hooks, linux >= 2.4.18-pre6 has five mangle hooks
 347                  * */
 348                 assert((h->info.valid_hooks
 349                         == (1 << NF_IP6_PRE_ROUTING
 350                             | 1 << NF_IP6_LOCAL_OUT)) ||
 351                        (h->info.valid_hooks
 352                         == (1 << NF_IP6_PRE_ROUTING
 353                             | 1 << NF_IP6_LOCAL_IN
 354                             | 1 << NF_IP6_FORWARD
 355                             | 1 << NF_IP6_LOCAL_OUT
 356                             | 1 << NF_IP6_POST_ROUTING)));
 357
 358                 /* Hooks should be first five */
 359                 assert(h->info.hook_entry[NF_IP6_PRE_ROUTING] == 0);
 360
 361                 n = get_chain_end(h, 0);
 362
 363                 if (h->info.valid_hooks & (1 << NF_IP6_LOCAL_IN)) {
 364                         n += get_entry(h, n)->next_offset;
 365                         assert(h->info.hook_entry[NF_IP6_LOCAL_IN] == n);
 366                         n = get_chain_end(h, n);
 367                 }
 368
 369                 if (h->info.valid_hooks & (1 << NF_IP6_FORWARD)) {
 370                         n += get_entry(h, n)->next_offset;
 371                         assert(h->info.hook_entry[NF_IP6_FORWARD] == n);
 372                         n = get_chain_end(h, n);
 373                 }
 374
 375                 n += get_entry(h, n)->next_offset;
 376                 assert(h->info.hook_entry[NF_IP6_LOCAL_OUT] == n);
 377                 user_offset = h->info.hook_entry[NF_IP6_LOCAL_OUT];
 378
 379                 if (h->info.valid_hooks & (1 << NF_IP6_POST_ROUTING)) {
 380                         n = get_chain_end(h, n);
 381                         n += get_entry(h, n)->next_offset;
 382                         assert(h->info.hook_entry[NF_IP6_POST_ROUTING] == n);
 383                         user_offset = h->info.hook_entry[NF_IP6_POST_ROUTING];
 384                 }
 385         } else {
 386                 fprintf(stderr, "Unknown table `%s'\n", h->info.name);
 387                 abort();
 388         }
 389
 390         /* User chain == end of last builtin + policy entry */
 391         user_offset = get_chain_end(h, user_offset);
 392         user_offset += get_entry(h, user_offset)->next_offset;
 393
 394         /* Overflows should be end of entry chains, and unconditional
 395            policy nodes. */
 396         for (i = 0; i < NUMHOOKS; i++) {
 397                 STRUCT_ENTRY *e;
 398                 STRUCT_STANDARD_TARGET *t;
 399
 400                 if (!(h->info.valid_hooks & (1 << i)))
 401                         continue;
 402                 assert(h->info.underflow[i]
 403                        == get_chain_end(h, h->info.hook_entry[i]));
 404
 405                 e = get_entry(h, get_chain_end(h, h->info.hook_entry[i]));
 406                 assert(unconditional(&e->ipv6));
 407                 assert(e->target_offset == sizeof(*e));
 408                 t = (STRUCT_STANDARD_TARGET *)GET_TARGET(e);
 409                 printf("target_size=%u, align=%u\n",
 410                         t->target.u.target_size, ALIGN(sizeof(*t)));
 411                 assert(t->target.u.target_size == ALIGN(sizeof(*t)));
 412                 assert(e->next_offset == sizeof(*e) + ALIGN(sizeof(*t)));
 413
 414                 assert(strcmp(t->target.u.user.name, STANDARD_TARGET)==0);
 415                 assert(t->verdict == -NF_DROP-1 || t->verdict == -NF_ACCEPT-1);
 416
 417                 /* Hooks and underflows must be valid entries */
 418                 entry2index(h, get_entry(h, h->info.hook_entry[i]));
 419                 entry2index(h, get_entry(h, h->info.underflow[i]));
 420         }
 421
 422         assert(h->info.size
 423                >= h->info.num_entries * (sizeof(STRUCT_ENTRY)
 424                                          +sizeof(STRUCT_STANDARD_TARGET)));
 425
 426         assert(h->entries.size
 427                >= (h->new_number
 428                    * (sizeof(STRUCT_ENTRY)
 429                       + sizeof(STRUCT_STANDARD_TARGET))));
 430         assert(strcmp(h->info.name, h->entries.name) == 0);
 431
 432         i = 0; n = 0;
 433         was_return = 0;
 434
 435 #if 0
 436         /* Check all the entries. */
 437         ENTRY_ITERATE(h->entries.entrytable, h->entries.size,
 438                       check_entry, &i, &n, user_offset, &was_return, h);
 439
 440         assert(i == h->new_number);
 441         assert(n == h->entries.size);
 442
 443         /* Final entry must be error node */
 444         assert(strcmp(GET_TARGET(index2entry(h, h->new_number-1))
 445                       ->u.user.name,
 446                       ERROR_TARGET) == 0);
 447 #endif
 448 }
 449 #endif /*IPTC_DEBUG*/