src/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 #define TC_NUM_RULES            ip6tc_num_rules
  93 #define TC_GET_RULE             ip6tc_get_rule
  94
  95 #define TC_AF                   AF_INET6
  96 #define TC_IPPROTO              IPPROTO_IPV6
  97
  98 #define SO_SET_REPLACE          IP6T_SO_SET_REPLACE
  99 #define SO_SET_ADD_COUNTERS     IP6T_SO_SET_ADD_COUNTERS
 100 #define SO_GET_INFO             IP6T_SO_GET_INFO
 101 #define SO_GET_ENTRIES          IP6T_SO_GET_ENTRIES
 102 #define SO_GET_VERSION          IP6T_SO_GET_VERSION
 103
 104 #define STANDARD_TARGET         IP6T_STANDARD_TARGET
 105 #define LABEL_RETURN            IP6TC_LABEL_RETURN
 106 #define LABEL_ACCEPT            IP6TC_LABEL_ACCEPT
 107 #define LABEL_DROP              IP6TC_LABEL_DROP
 108 #define LABEL_QUEUE             IP6TC_LABEL_QUEUE
 109
 110 #define ALIGN                   IP6T_ALIGN
 111 #define RETURN                  IP6T_RETURN
 112
 113 #include "libiptc.c"
 114
 115 #define BIT6(a, l) \
 116  ((ntohl(a->in6_u.u6_addr32[(l) / 32]) >> (31 - ((l) & 31))) & 1)
 117
 118 int
 119 ipv6_prefix_length(const struct in6_addr *a)
 120 {
 121         int l, i;
 122         for (l = 0; l < 128; l++) {
 123                 if (BIT6(a, l) == 0)
 124                         break;
 125         }
 126         for (i = l + 1; i < 128; i++) {
 127                 if (BIT6(a, i) == 1)
 128                         return -1;
 129         }
 130         return l;
 131 }
 132
 133 static int
 134 dump_entry(struct ip6t_entry *e, const ip6tc_handle_t handle)
 135 {
 136         size_t i;
 137         char buf[40];
 138         int len;
 139         struct ip6t_entry_target *t;
 140
 141         printf("Entry %u (%lu):\n", iptcb_entry2index(handle, e),
 142                iptcb_entry2offset(handle, e));
 143         puts("SRC IP: ");
 144         inet_ntop(AF_INET6, &e->ipv6.src, buf, sizeof buf);
 145         puts(buf);
 146         putchar('/');
 147         len = ipv6_prefix_length(&e->ipv6.smsk);
 148         if (len != -1)
 149                 printf("%d", len);
 150         else {
 151                 inet_ntop(AF_INET6, &e->ipv6.smsk, buf, sizeof buf);
 152                 puts(buf);
 153         }
 154         putchar('\n');
 155
 156         puts("DST IP: ");
 157         inet_ntop(AF_INET6, &e->ipv6.dst, buf, sizeof buf);
 158         puts(buf);
 159         putchar('/');
 160         len = ipv6_prefix_length(&e->ipv6.dmsk);
 161         if (len != -1)
 162                 printf("%d", len);
 163         else {
 164                 inet_ntop(AF_INET6, &e->ipv6.dmsk, buf, sizeof buf);
 165                 puts(buf);
 166         }
 167         putchar('\n');
 168
 169         printf("Interface: `%s'/", e->ipv6.iniface);
 170         for (i = 0; i < IFNAMSIZ; i++)
 171                 printf("%c", e->ipv6.iniface_mask[i] ? 'X' : '.');
 172         printf("to `%s'/", e->ipv6.outiface);
 173         for (i = 0; i < IFNAMSIZ; i++)
 174                 printf("%c", e->ipv6.outiface_mask[i] ? 'X' : '.');
 175         printf("\nProtocol: %u\n", e->ipv6.proto);
 176         if (e->ipv6.flags & IP6T_F_TOS)
 177                 printf("TOS: %u\n", e->ipv6.tos);
 178         printf("Flags: %02X\n", e->ipv6.flags);
 179         printf("Invflags: %02X\n", e->ipv6.invflags);
 180         printf("Counters: %llu packets, %llu bytes\n",
 181                (unsigned long long)e->counters.pcnt, (unsigned long long)e->counters.bcnt);
 182         printf("Cache: %08X ", e->nfcache);
 183         if (e->nfcache & NFC_ALTERED) printf("ALTERED ");
 184         if (e->nfcache & NFC_UNKNOWN) printf("UNKNOWN ");
 185         printf("\n");
 186
 187         IP6T_MATCH_ITERATE(e, print_match);
 188
 189         t = ip6t_get_target(e);
 190         printf("Target name: `%s' [%u]\n", t->u.user.name, t->u.target_size);
 191         if (strcmp(t->u.user.name, IP6T_STANDARD_TARGET) == 0) {
 192                 int pos = *(int *)t->data;
 193                 if (pos < 0)
 194                         printf("verdict=%s\n",
 195                                pos == -NF_ACCEPT-1 ? "NF_ACCEPT"
 196                                : pos == -NF_DROP-1 ? "NF_DROP"
 197                                : pos == IP6T_RETURN ? "RETURN"
 198                                : "UNKNOWN");
 199                 else
 200                         printf("verdict=%u\n", pos);
 201         } else if (strcmp(t->u.user.name, IP6T_ERROR_TARGET) == 0)
 202                 printf("error=`%s'\n", t->data);
 203
 204         printf("\n");
 205         return 0;
 206 }
 207
 208 static unsigned char *
 209 is_same(const STRUCT_ENTRY *a, const STRUCT_ENTRY *b,
 210         unsigned char *matchmask)
 211 {
 212         unsigned int i;
 213         unsigned char *mptr;
 214
 215         /* Always compare head structures: ignore mask here. */
 216         if (memcmp(&a->ipv6.src, &b->ipv6.src, sizeof(struct in6_addr))
 217             || memcmp(&a->ipv6.dst, &b->ipv6.dst, sizeof(struct in6_addr))
 218             || memcmp(&a->ipv6.smsk, &b->ipv6.smsk, sizeof(struct in6_addr))
 219             || memcmp(&a->ipv6.dmsk, &b->ipv6.dmsk, sizeof(struct in6_addr))
 220             || a->ipv6.proto != b->ipv6.proto
 221             || a->ipv6.tos != b->ipv6.tos
 222             || a->ipv6.flags != b->ipv6.flags
 223             || a->ipv6.invflags != b->ipv6.invflags)
 224                 return NULL;
 225
 226         for (i = 0; i < IFNAMSIZ; i++) {
 227                 if (a->ipv6.iniface_mask[i] != b->ipv6.iniface_mask[i])
 228                         return NULL;
 229                 if ((a->ipv6.iniface[i] & a->ipv6.iniface_mask[i])
 230                     != (b->ipv6.iniface[i] & b->ipv6.iniface_mask[i]))
 231                         return NULL;
 232                 if (a->ipv6.outiface_mask[i] != b->ipv6.outiface_mask[i])
 233                         return NULL;
 234                 if ((a->ipv6.outiface[i] & a->ipv6.outiface_mask[i])
 235                     != (b->ipv6.outiface[i] & b->ipv6.outiface_mask[i]))
 236                         return NULL;
 237         }
 238
 239         if (a->nfcache != b->nfcache
 240             || a->target_offset != b->target_offset
 241             || a->next_offset != b->next_offset)
 242                 return NULL;
 243
 244         mptr = matchmask + sizeof(STRUCT_ENTRY);
 245         if (IP6T_MATCH_ITERATE(a, match_different, a->elems, b->elems, &mptr))
 246                 return NULL;
 247         mptr += IP6T_ALIGN(sizeof(struct ip6t_entry_target));
 248
 249         return mptr;
 250 }
 251
 252 /* All zeroes == unconditional rule. */
 253 static inline int
 254 unconditional(const struct ip6t_ip6 *ipv6)
 255 {
 256         unsigned int i;
 257
 258         for (i = 0; i < sizeof(*ipv6); i++)
 259                 if (((char *)ipv6)[i])
 260                         break;
 261
 262         return (i == sizeof(*ipv6));
 263 }
 264
 265 #ifdef IPTC_DEBUG
 266 /* Do every conceivable sanity check on the handle */
 267 static void
 268 do_check(TC_HANDLE_T h, unsigned int line)
 269 {
 270         unsigned int i, n;
 271         unsigned int user_offset; /* Offset of first user chain */
 272         int was_return;
 273
 274         assert(h->changed == 0 || h->changed == 1);
 275         if (strcmp(h->info.name, "filter") == 0) {
 276                 assert(h->info.valid_hooks
 277                        == (1 << NF_IP6_LOCAL_IN
 278                            | 1 << NF_IP6_FORWARD
 279                            | 1 << NF_IP6_LOCAL_OUT));
 280
 281                 /* Hooks should be first three */
 282                 assert(h->info.hook_entry[NF_IP6_LOCAL_IN] == 0);
 283
 284                 n = get_chain_end(h, 0);
 285                 n += get_entry(h, n)->next_offset;
 286                 assert(h->info.hook_entry[NF_IP6_FORWARD] == n);
 287
 288                 n = get_chain_end(h, n);
 289                 n += get_entry(h, n)->next_offset;
 290                 assert(h->info.hook_entry[NF_IP6_LOCAL_OUT] == n);
 291
 292                 user_offset = h->info.hook_entry[NF_IP6_LOCAL_OUT];
 293         } else if (strcmp(h->info.name, "nat") == 0) {
 294                 assert((h->info.valid_hooks
 295                         == (1 << NF_IP6_PRE_ROUTING
 296                             | 1 << NF_IP6_LOCAL_OUT
 297                             | 1 << NF_IP6_POST_ROUTING)) ||
 298                        (h->info.valid_hooks
 299                         == (1 << NF_IP6_PRE_ROUTING
 300                             | 1 << NF_IP6_LOCAL_IN
 301                             | 1 << NF_IP6_LOCAL_OUT
 302                             | 1 << NF_IP6_POST_ROUTING)));
 303
 304                 assert(h->info.hook_entry[NF_IP6_PRE_ROUTING] == 0);
 305
 306                 n = get_chain_end(h, 0);
 307
 308                 n += get_entry(h, n)->next_offset;
 309                 assert(h->info.hook_entry[NF_IP6_POST_ROUTING] == n);
 310                 n = get_chain_end(h, n);
 311
 312                 n += get_entry(h, n)->next_offset;
 313                 assert(h->info.hook_entry[NF_IP6_LOCAL_OUT] == n);
 314                 user_offset = h->info.hook_entry[NF_IP6_LOCAL_OUT];
 315
 316                 if (h->info.valid_hooks & (1 << NF_IP6_LOCAL_IN)) {
 317                         n = get_chain_end(h, n);
 318                         n += get_entry(h, n)->next_offset;
 319                         assert(h->info.hook_entry[NF_IP6_LOCAL_IN] == n);
 320                         user_offset = h->info.hook_entry[NF_IP6_LOCAL_IN];
 321                 }
 322
 323         } else if (strcmp(h->info.name, "mangle") == 0) {
 324                 /* This code is getting ugly because linux < 2.4.18-pre6 had
 325                  * two mangle hooks, linux >= 2.4.18-pre6 has five mangle hooks
 326                  * */
 327                 assert((h->info.valid_hooks
 328                         == (1 << NF_IP6_PRE_ROUTING
 329                             | 1 << NF_IP6_LOCAL_OUT)) ||
 330                        (h->info.valid_hooks
 331                         == (1 << NF_IP6_PRE_ROUTING
 332                             | 1 << NF_IP6_LOCAL_IN
 333                             | 1 << NF_IP6_FORWARD
 334                             | 1 << NF_IP6_LOCAL_OUT
 335                             | 1 << NF_IP6_POST_ROUTING)));
 336
 337                 /* Hooks should be first five */
 338                 assert(h->info.hook_entry[NF_IP6_PRE_ROUTING] == 0);
 339
 340                 n = get_chain_end(h, 0);
 341
 342                 if (h->info.valid_hooks & (1 << NF_IP6_LOCAL_IN)) {
 343                         n += get_entry(h, n)->next_offset;
 344                         assert(h->info.hook_entry[NF_IP6_LOCAL_IN] == n);
 345                         n = get_chain_end(h, n);
 346                 }
 347
 348                 if (h->info.valid_hooks & (1 << NF_IP6_FORWARD)) {
 349                         n += get_entry(h, n)->next_offset;
 350                         assert(h->info.hook_entry[NF_IP6_FORWARD] == n);
 351                         n = get_chain_end(h, n);
 352                 }
 353
 354                 n += get_entry(h, n)->next_offset;
 355                 assert(h->info.hook_entry[NF_IP6_LOCAL_OUT] == n);
 356                 user_offset = h->info.hook_entry[NF_IP6_LOCAL_OUT];
 357
 358                 if (h->info.valid_hooks & (1 << NF_IP6_POST_ROUTING)) {
 359                         n = get_chain_end(h, n);
 360                         n += get_entry(h, n)->next_offset;
 361                         assert(h->info.hook_entry[NF_IP6_POST_ROUTING] == n);
 362                         user_offset = h->info.hook_entry[NF_IP6_POST_ROUTING];
 363                 }
 364         } else if (strcmp(h->info.name, "raw") == 0) {
 365                 assert(h->info.valid_hooks
 366                        == (1 << NF_IP6_PRE_ROUTING
 367                            | 1 << NF_IP6_LOCAL_OUT));
 368
 369                 /* Hooks should be first three */
 370                 assert(h->info.hook_entry[NF_IP6_PRE_ROUTING] == 0);
 371
 372                 n = get_chain_end(h, n);
 373                 n += get_entry(h, n)->next_offset;
 374                 assert(h->info.hook_entry[NF_IP6_LOCAL_OUT] == n);
 375
 376                 user_offset = h->info.hook_entry[NF_IP6_LOCAL_OUT];
 377         } else {
 378                 fprintf(stderr, "Unknown table `%s'\n", h->info.name);
 379                 abort();
 380         }
 381
 382         /* User chain == end of last builtin + policy entry */
 383         user_offset = get_chain_end(h, user_offset);
 384         user_offset += get_entry(h, user_offset)->next_offset;
 385
 386         /* Overflows should be end of entry chains, and unconditional
 387            policy nodes. */
 388         for (i = 0; i < NUMHOOKS; i++) {
 389                 STRUCT_ENTRY *e;
 390                 STRUCT_STANDARD_TARGET *t;
 391
 392                 if (!(h->info.valid_hooks & (1 << i)))
 393                         continue;
 394                 assert(h->info.underflow[i]
 395                        == get_chain_end(h, h->info.hook_entry[i]));
 396
 397                 e = get_entry(h, get_chain_end(h, h->info.hook_entry[i]));
 398                 assert(unconditional(&e->ipv6));
 399                 assert(e->target_offset == sizeof(*e));
 400                 t = (STRUCT_STANDARD_TARGET *)GET_TARGET(e);
 401                 printf("target_size=%u, align=%u\n",
 402                         t->target.u.target_size, ALIGN(sizeof(*t)));
 403                 assert(t->target.u.target_size == ALIGN(sizeof(*t)));
 404                 assert(e->next_offset == sizeof(*e) + ALIGN(sizeof(*t)));
 405
 406                 assert(strcmp(t->target.u.user.name, STANDARD_TARGET)==0);
 407                 assert(t->verdict == -NF_DROP-1 || t->verdict == -NF_ACCEPT-1);
 408
 409                 /* Hooks and underflows must be valid entries */
 410                 iptcb_entry2index(h, get_entry(h, h->info.hook_entry[i]));
 411                 iptcb_entry2index(h, get_entry(h, h->info.underflow[i]));
 412         }
 413
 414         assert(h->info.size
 415                >= h->info.num_entries * (sizeof(STRUCT_ENTRY)
 416                                          +sizeof(STRUCT_STANDARD_TARGET)));
 417
 418         assert(h->entries.size
 419                >= (h->new_number
 420                    * (sizeof(STRUCT_ENTRY)
 421                       + sizeof(STRUCT_STANDARD_TARGET))));
 422         assert(strcmp(h->info.name, h->entries.name) == 0);
 423
 424         i = 0; n = 0;
 425         was_return = 0;
 426
 427 #if 0
 428         /* Check all the entries. */
 429         ENTRY_ITERATE(h->entries.entrytable, h->entries.size,
 430                       check_entry, &i, &n, user_offset, &was_return, h);
 431
 432         assert(i == h->new_number);
 433         assert(n == h->entries.size);
 434
 435         /* Final entry must be error node */
 436         assert(strcmp(GET_TARGET(index2entry(h, h->new_number-1))
 437                       ->u.user.name,
 438                       ERROR_TARGET) == 0);
 439 #endif
 440 }
 441 #endif /*IPTC_DEBUG*/