/* Library which manipulates firewall rules. Version $Revision$ */ /* Architecture of firewall rules is as follows: * * Chains go INPUT, FORWARD, OUTPUT then user chains. * Each user chain starts with an ERROR node. * Every chain ends with an unconditional jump: a RETURN for user chains, * and a POLICY for built-ins. */ /* (C) 1999 Paul ``Rusty'' Russell - Placed under the GNU GPL (See * COPYING for details). * (C) 2000-2004 by the Netfilter Core Team * * 2003-Jun-20: Harald Welte : * - Reimplementation of chain cache to use offsets instead of entries * 2003-Jun-23: Harald Welte : * - performance optimization, sponsored by Astaro AG (http://www.astaro.com/) * don't rebuild the chain cache after every operation, instead fix it * up after a ruleset change. * 2004-Aug-18: Harald Welte : * - further performance work: total reimplementation of libiptc. * - libiptc now has a real internal (linked-list) represntation of the * ruleset and a parser/compiler from/to this internal representation * - again sponsored by Astaro AG (http://www.astaro.com/) * * 2008-Jan+Jul: Jesper Dangaard Brouer * - performance work: speedup chain list "name" searching. * - performance work: speedup initial ruleset parsing. * - sponsored by ComX Networks A/S (http://www.comx.dk/) */ #include #include #include #include #include #include #include #include "linux_list.h" //#define IPTC_DEBUG2 1 #ifdef IPTC_DEBUG2 #include #define DEBUGP(x, args...) fprintf(stderr, "%s: " x, __FUNCTION__, ## args) #define DEBUGP_C(x, args...) fprintf(stderr, x, ## args) #else #define DEBUGP(x, args...) #define DEBUGP_C(x, args...) #endif #ifdef DEBUG #define debug(x, args...) fprintf(stderr, x, ## args) #else #define debug(x, args...) #endif static void *iptc_fn = NULL; static const char *hooknames[] = { [HOOK_PRE_ROUTING] = "PREROUTING", [HOOK_LOCAL_IN] = "INPUT", [HOOK_FORWARD] = "FORWARD", [HOOK_LOCAL_OUT] = "OUTPUT", [HOOK_POST_ROUTING] = "POSTROUTING", }; /* Convenience structures */ struct chain_head; struct rule_head; struct counter_map { enum { COUNTER_MAP_NOMAP, COUNTER_MAP_NORMAL_MAP, COUNTER_MAP_ZEROED, COUNTER_MAP_SET } maptype; unsigned int mappos; }; enum iptcc_rule_type { IPTCC_R_STANDARD, /* standard target (ACCEPT, ...) */ IPTCC_R_MODULE, /* extension module (SNAT, ...) */ IPTCC_R_FALLTHROUGH, /* fallthrough rule */ IPTCC_R_JUMP, /* jump to other chain */ }; struct rule_head { struct list_head list; struct chain_head *chain; struct counter_map counter_map; unsigned int index; /* index (needed for counter_map) */ unsigned int offset; /* offset in rule blob */ enum iptcc_rule_type type; struct chain_head *jump; /* jump target, if IPTCC_R_JUMP */ unsigned int size; /* size of entry data */ STRUCT_ENTRY entry[0]; }; struct chain_head { struct list_head list; char name[TABLE_MAXNAMELEN]; unsigned int hooknum; /* hook number+1 if builtin */ unsigned int references; /* how many jumps reference us */ int verdict; /* verdict if builtin */ STRUCT_COUNTERS counters; /* per-chain counters */ struct counter_map counter_map; unsigned int num_rules; /* number of rules in list */ struct list_head rules; /* list of rules */ unsigned int index; /* index (needed for jump resolval) */ unsigned int head_offset; /* offset in rule blob */ unsigned int foot_index; /* index (needed for counter_map) */ unsigned int foot_offset; /* offset in rule blob */ }; struct xtc_handle { int sockfd; int changed; /* Have changes been made? */ struct list_head chains; struct chain_head *chain_iterator_cur; struct rule_head *rule_iterator_cur; unsigned int num_chains; /* number of user defined chains */ struct chain_head **chain_index; /* array for fast chain list access*/ unsigned int chain_index_sz;/* size of chain index array */ int sorted_offsets; /* if chains are received sorted from kernel, * then the offsets are also sorted. Says if its * possible to bsearch offsets using chain_index. */ STRUCT_GETINFO info; STRUCT_GET_ENTRIES *entries; }; enum bsearch_type { BSEARCH_NAME, /* Binary search after chain name */ BSEARCH_OFFSET, /* Binary search based on offset */ }; /* allocate a new chain head for the cache */ static struct chain_head *iptcc_alloc_chain_head(const char *name, int hooknum) { struct chain_head *c = malloc(sizeof(*c)); if (!c) return NULL; memset(c, 0, sizeof(*c)); strncpy(c->name, name, TABLE_MAXNAMELEN); c->hooknum = hooknum; INIT_LIST_HEAD(&c->rules); return c; } /* allocate and initialize a new rule for the cache */ static struct rule_head *iptcc_alloc_rule(struct chain_head *c, unsigned int size) { struct rule_head *r = malloc(sizeof(*r)+size); if (!r) return NULL; memset(r, 0, sizeof(*r)); r->chain = c; r->size = size; return r; } /* notify us that the ruleset has been modified by the user */ static inline void set_changed(struct xtc_handle *h) { h->changed = 1; } #ifdef IPTC_DEBUG static void do_check(struct xtc_handle *h, unsigned int line); #define CHECK(h) do { if (!getenv("IPTC_NO_CHECK")) do_check((h), __LINE__); } while(0) #else #define CHECK(h) #endif /********************************************************************** * iptc blob utility functions (iptcb_*) **********************************************************************/ static inline int iptcb_get_number(const STRUCT_ENTRY *i, const STRUCT_ENTRY *seek, unsigned int *pos) { if (i == seek) return 1; (*pos)++; return 0; } static inline int iptcb_get_entry_n(STRUCT_ENTRY *i, unsigned int number, unsigned int *pos, STRUCT_ENTRY **pe) { if (*pos == number) { *pe = i; return 1; } (*pos)++; return 0; } static inline STRUCT_ENTRY * iptcb_get_entry(struct xtc_handle *h, unsigned int offset) { return (STRUCT_ENTRY *)((char *)h->entries->entrytable + offset); } static unsigned int iptcb_entry2index(struct xtc_handle *const h, const STRUCT_ENTRY *seek) { unsigned int pos = 0; if (ENTRY_ITERATE(h->entries->entrytable, h->entries->size, iptcb_get_number, seek, &pos) == 0) { fprintf(stderr, "ERROR: offset %u not an entry!\n", (unsigned int)((char *)seek - (char *)h->entries->entrytable)); abort(); } return pos; } static inline STRUCT_ENTRY * iptcb_offset2entry(struct xtc_handle *h, unsigned int offset) { return (STRUCT_ENTRY *) ((void *)h->entries->entrytable+offset); } static inline unsigned long iptcb_entry2offset(struct xtc_handle *const h, const STRUCT_ENTRY *e) { return (void *)e - (void *)h->entries->entrytable; } static inline unsigned int iptcb_offset2index(struct xtc_handle *const h, unsigned int offset) { return iptcb_entry2index(h, iptcb_offset2entry(h, offset)); } /* Returns 0 if not hook entry, else hooknumber + 1 */ static inline unsigned int iptcb_ent_is_hook_entry(STRUCT_ENTRY *e, struct xtc_handle *h) { unsigned int i; for (i = 0; i < NUMHOOKS; i++) { if ((h->info.valid_hooks & (1 << i)) && iptcb_get_entry(h, h->info.hook_entry[i]) == e) return i+1; } return 0; } /********************************************************************** * Chain index (cache utility) functions ********************************************************************** * The chain index is an array with pointers into the chain list, with * CHAIN_INDEX_BUCKET_LEN spacing. This facilitates the ability to * speedup chain list searching, by find a more optimal starting * points when searching the linked list. * * The starting point can be found fast by using a binary search of * the chain index. Thus, reducing the previous search complexity of * O(n) to O(log(n/k) + k) where k is CHAIN_INDEX_BUCKET_LEN. * * A nice property of the chain index, is that the "bucket" list * length is max CHAIN_INDEX_BUCKET_LEN (when just build, inserts will * change this). Oppose to hashing, where the "bucket" list length can * vary a lot. */ #ifndef CHAIN_INDEX_BUCKET_LEN #define CHAIN_INDEX_BUCKET_LEN 40 #endif /* Another nice property of the chain index is that inserting/creating * chains in chain list don't change the correctness of the chain * index, it only causes longer lists in the buckets. * * To mitigate the performance penalty of longer bucket lists and the * penalty of rebuilding, the chain index is rebuild only when * CHAIN_INDEX_INSERT_MAX chains has been added. */ #ifndef CHAIN_INDEX_INSERT_MAX #define CHAIN_INDEX_INSERT_MAX 355 #endif static inline unsigned int iptcc_is_builtin(struct chain_head *c); /* Use binary search in the chain index array, to find a chain_head * pointer closest to the place of the searched name element. * * Notes that, binary search (obviously) requires that the chain list * is sorted by name. * * The not so obvious: The chain index array, is actually both sorted * by name and offset, at the same time!. This is only true because, * chain are stored sorted in the kernel (as we pushed it in sorted). * */ static struct list_head * __iptcc_bsearch_chain_index(const char *name, unsigned int offset, unsigned int *idx, struct xtc_handle *handle, enum bsearch_type type) { unsigned int pos, end; int res; struct list_head *list_pos; list_pos=&handle->chains; /* Check for empty array, e.g. no user defined chains */ if (handle->chain_index_sz == 0) { debug("WARNING: handle->chain_index_sz == 0\n"); return list_pos; } /* Init */ end = handle->chain_index_sz; pos = end / 2; debug("bsearch Find chain:%s (pos:%d end:%d) (offset:%d)\n", name, pos, end, offset); /* Loop */ loop: if (!handle->chain_index[pos]) { fprintf(stderr, "ERROR: NULL pointer chain_index[%d]\n", pos); return &handle->chains; /* Be safe, return orig start pos */ } debug("bsearch Index[%d] name:%s ", pos, handle->chain_index[pos]->name); /* Support for different compare functions */ switch (type) { case BSEARCH_NAME: res = strcmp(name, handle->chain_index[pos]->name); break; case BSEARCH_OFFSET: debug("head_offset:[%d] foot_offset:[%d] ", handle->chain_index[pos]->head_offset, handle->chain_index[pos]->foot_offset); res = offset - handle->chain_index[pos]->head_offset; break; default: fprintf(stderr, "ERROR: %d not a valid bsearch type\n", type); abort(); break; } debug("res:%d ", res); list_pos = &handle->chain_index[pos]->list; *idx = pos; if (res == 0) { /* Found element, by direct hit */ debug("[found] Direct hit pos:%d end:%d\n", pos, end); return list_pos; } else if (res < 0) { /* Too far, jump back */ end = pos; pos = pos / 2; /* Exit case: First element of array */ if (end == 0) { debug("[found] Reached first array elem (end%d)\n",end); return list_pos; } debug("jump back to pos:%d (end:%d)\n", pos, end); goto loop; } else { /* res > 0; Not far enough, jump forward */ /* Exit case: Last element of array */ if (pos == handle->chain_index_sz-1) { debug("[found] Last array elem (end:%d)\n", end); return list_pos; } /* Exit case: Next index less, thus elem in this list section */ switch (type) { case BSEARCH_NAME: res = strcmp(name, handle->chain_index[pos+1]->name); break; case BSEARCH_OFFSET: res = offset - handle->chain_index[pos+1]->head_offset; break; } if (res < 0) { debug("[found] closest list (end:%d)\n", end); return list_pos; } pos = (pos+end)/2; debug("jump forward to pos:%d (end:%d)\n", pos, end); goto loop; } } /* Wrapper for string chain name based bsearch */ static struct list_head * iptcc_bsearch_chain_index(const char *name, unsigned int *idx, struct xtc_handle *handle) { return __iptcc_bsearch_chain_index(name, 0, idx, handle, BSEARCH_NAME); } /* Wrapper for offset chain based bsearch */ static struct list_head * iptcc_bsearch_chain_offset(unsigned int offset, unsigned int *idx, struct xtc_handle *handle) { struct list_head *pos; /* If chains were not received sorted from kernel, then the * offset bsearch is not possible. */ if (!handle->sorted_offsets) pos = handle->chains.next; else pos = __iptcc_bsearch_chain_index(NULL, offset, idx, handle, BSEARCH_OFFSET); return pos; } #ifdef DEBUG /* Trivial linear search of chain index. Function used for verifying the output of bsearch function */ static struct list_head * iptcc_linearly_search_chain_index(const char *name, struct xtc_handle *handle) { unsigned int i=0; int res=0; struct list_head *list_pos; list_pos = &handle->chains; if (handle->chain_index_sz) list_pos = &handle->chain_index[0]->list; /* Linearly walk of chain index array */ for (i=0; i < handle->chain_index_sz; i++) { if (handle->chain_index[i]) { res = strcmp(handle->chain_index[i]->name, name); if (res > 0) break; // One step too far list_pos = &handle->chain_index[i]->list; if (res == 0) break; // Direct hit } } return list_pos; } #endif static int iptcc_chain_index_alloc(struct xtc_handle *h) { unsigned int list_length = CHAIN_INDEX_BUCKET_LEN; unsigned int array_elems; unsigned int array_mem; /* Allocate memory for the chain index array */ array_elems = (h->num_chains / list_length) + (h->num_chains % list_length ? 1 : 0); array_mem = sizeof(h->chain_index) * array_elems; debug("Alloc Chain index, elems:%d mem:%d bytes\n", array_elems, array_mem); h->chain_index = malloc(array_mem); if (h->chain_index == NULL && array_mem > 0) { h->chain_index_sz = 0; return -ENOMEM; } memset(h->chain_index, 0, array_mem); h->chain_index_sz = array_elems; return 1; } static void iptcc_chain_index_free(struct xtc_handle *h) { h->chain_index_sz = 0; free(h->chain_index); } #ifdef DEBUG static void iptcc_chain_index_dump(struct xtc_handle *h) { unsigned int i = 0; /* Dump: contents of chain index array */ for (i=0; i < h->chain_index_sz; i++) { if (h->chain_index[i]) { fprintf(stderr, "Chain index[%d].name: %s\n", i, h->chain_index[i]->name); } } } #endif /* Build the chain index */ static int iptcc_chain_index_build(struct xtc_handle *h) { unsigned int list_length = CHAIN_INDEX_BUCKET_LEN; unsigned int chains = 0; unsigned int cindex = 0; struct chain_head *c; /* Build up the chain index array here */ debug("Building chain index\n"); debug("Number of user defined chains:%d bucket_sz:%d array_sz:%d\n", h->num_chains, list_length, h->chain_index_sz); if (h->chain_index_sz == 0) return 0; list_for_each_entry(c, &h->chains, list) { /* Issue: The index array needs to start after the * builtin chains, as they are not sorted */ if (!iptcc_is_builtin(c)) { cindex=chains / list_length; /* Safe guard, break out on array limit, this * is useful if chains are added and array is * rebuild, without realloc of memory. */ if (cindex >= h->chain_index_sz) break; if ((chains % list_length)== 0) { debug("\nIndex[%d] Chains:", cindex); h->chain_index[cindex] = c; } chains++; } debug("%s, ", c->name); } debug("\n"); return 1; } static int iptcc_chain_index_rebuild(struct xtc_handle *h) { debug("REBUILD chain index array\n"); iptcc_chain_index_free(h); if ((iptcc_chain_index_alloc(h)) < 0) return -ENOMEM; iptcc_chain_index_build(h); return 1; } /* Delete chain (pointer) from index array. Removing an element from * the chain list only affects the chain index array, if the chain * index points-to/uses that list pointer. * * There are different strategies, the simple and safe is to rebuild * the chain index every time. The more advanced is to update the * array index to point to the next element, but that requires some * house keeping and boundary checks. The advanced is implemented, as * the simple approach behaves badly when all chains are deleted * because list_for_each processing will always hit the first chain * index, thus causing a rebuild for every chain. */ static int iptcc_chain_index_delete_chain(struct chain_head *c, struct xtc_handle *h) { struct list_head *index_ptr, *next; struct chain_head *c2; unsigned int idx, idx2; index_ptr = iptcc_bsearch_chain_index(c->name, &idx, h); debug("Del chain[%s] c->list:%p index_ptr:%p\n", c->name, &c->list, index_ptr); /* Save the next pointer */ next = c->list.next; list_del(&c->list); if (index_ptr == &c->list) { /* Chain used as index ptr */ /* See if its possible to avoid a rebuild, by shifting * to next pointer. Its possible if the next pointer * is located in the same index bucket. */ c2 = list_entry(next, struct chain_head, list); iptcc_bsearch_chain_index(c2->name, &idx2, h); if (idx != idx2) { /* Rebuild needed */ return iptcc_chain_index_rebuild(h); } else { /* Avoiding rebuild */ debug("Update cindex[%d] with next ptr name:[%s]\n", idx, c2->name); h->chain_index[idx]=c2; return 0; } } return 0; } /********************************************************************** * iptc cache utility functions (iptcc_*) **********************************************************************/ /* Is the given chain builtin (1) or user-defined (0) */ static inline unsigned int iptcc_is_builtin(struct chain_head *c) { return (c->hooknum ? 1 : 0); } /* Get a specific rule within a chain */ static struct rule_head *iptcc_get_rule_num(struct chain_head *c, unsigned int rulenum) { struct rule_head *r; unsigned int num = 0; list_for_each_entry(r, &c->rules, list) { num++; if (num == rulenum) return r; } return NULL; } /* Get a specific rule within a chain backwards */ static struct rule_head *iptcc_get_rule_num_reverse(struct chain_head *c, unsigned int rulenum) { struct rule_head *r; unsigned int num = 0; list_for_each_entry_reverse(r, &c->rules, list) { num++; if (num == rulenum) return r; } return NULL; } /* Returns chain head if found, otherwise NULL. */ static struct chain_head * iptcc_find_chain_by_offset(struct xtc_handle *handle, unsigned int offset) { struct list_head *pos; struct list_head *list_start_pos; unsigned int i; if (list_empty(&handle->chains)) return NULL; /* Find a smart place to start the search */ list_start_pos = iptcc_bsearch_chain_offset(offset, &i, handle); /* Note that iptcc_bsearch_chain_offset() skips builtin * chains, but this function is only used for finding jump * targets, and a buildin chain is not a valid jump target */ debug("Offset:[%u] starting search at index:[%u]\n", offset, i); // list_for_each(pos, &handle->chains) { list_for_each(pos, list_start_pos->prev) { struct chain_head *c = list_entry(pos, struct chain_head, list); debug("."); if (offset >= c->head_offset && offset <= c->foot_offset) { debug("Offset search found chain:[%s]\n", c->name); return c; } } return NULL; } /* Returns chain head if found, otherwise NULL. */ static struct chain_head * iptcc_find_label(const char *name, struct xtc_handle *handle) { struct list_head *pos; struct list_head *list_start_pos; unsigned int i=0; int res; if (list_empty(&handle->chains)) return NULL; /* First look at builtin chains */ list_for_each(pos, &handle->chains) { struct chain_head *c = list_entry(pos, struct chain_head, list); if (!iptcc_is_builtin(c)) break; if (!strcmp(c->name, name)) return c; } /* Find a smart place to start the search via chain index */ //list_start_pos = iptcc_linearly_search_chain_index(name, handle); list_start_pos = iptcc_bsearch_chain_index(name, &i, handle); /* Handel if bsearch bails out early */ if (list_start_pos == &handle->chains) { list_start_pos = pos; } #ifdef DEBUG else { /* Verify result of bsearch against linearly index search */ struct list_head *test_pos; struct chain_head *test_c, *tmp_c; test_pos = iptcc_linearly_search_chain_index(name, handle); if (list_start_pos != test_pos) { debug("BUG in chain_index search\n"); test_c=list_entry(test_pos, struct chain_head,list); tmp_c =list_entry(list_start_pos,struct chain_head,list); debug("Verify search found:\n"); debug(" Chain:%s\n", test_c->name); debug("BSearch found:\n"); debug(" Chain:%s\n", tmp_c->name); exit(42); } } #endif /* Initial/special case, no user defined chains */ if (handle->num_chains == 0) return NULL; /* Start searching through the chain list */ list_for_each(pos, list_start_pos->prev) { struct chain_head *c = list_entry(pos, struct chain_head, list); res = strcmp(c->name, name); debug("List search name:%s == %s res:%d\n", name, c->name, res); if (res==0) return c; /* We can stop earlier as we know list is sorted */ if (res>0 && !iptcc_is_builtin(c)) { /* Walked too far*/ debug(" Not in list, walked too far, sorted list\n"); return NULL; } /* Stop on wrap around, if list head is reached */ if (pos == &handle->chains) { debug("Stop, list head reached\n"); return NULL; } } debug("List search NOT found name:%s\n", name); return NULL; } /* called when rule is to be removed from cache */ static void iptcc_delete_rule(struct rule_head *r) { DEBUGP("deleting rule %p (offset %u)\n", r, r->offset); /* clean up reference count of called chain */ if (r->type == IPTCC_R_JUMP && r->jump) r->jump->references--; list_del(&r->list); free(r); } /********************************************************************** * RULESET PARSER (blob -> cache) **********************************************************************/ /* Delete policy rule of previous chain, since cache doesn't contain * chain policy rules. * WARNING: This function has ugly design and relies on a lot of context, only * to be called from specific places within the parser */ static int __iptcc_p_del_policy(struct xtc_handle *h, unsigned int num) { const unsigned char *data; if (h->chain_iterator_cur) { /* policy rule is last rule */ struct rule_head *pr = (struct rule_head *) h->chain_iterator_cur->rules.prev; /* save verdict */ data = GET_TARGET(pr->entry)->data; h->chain_iterator_cur->verdict = *(const int *)data; /* save counter and counter_map information */ h->chain_iterator_cur->counter_map.maptype = COUNTER_MAP_ZEROED; h->chain_iterator_cur->counter_map.mappos = num-1; memcpy(&h->chain_iterator_cur->counters, &pr->entry->counters, sizeof(h->chain_iterator_cur->counters)); /* foot_offset points to verdict rule */ h->chain_iterator_cur->foot_index = num; h->chain_iterator_cur->foot_offset = pr->offset; /* delete rule from cache */ iptcc_delete_rule(pr); h->chain_iterator_cur->num_rules--; return 1; } return 0; } /* alphabetically insert a chain into the list */ static void iptc_insert_chain(struct xtc_handle *h, struct chain_head *c) { struct chain_head *tmp; struct list_head *list_start_pos; unsigned int i=1; /* Find a smart place to start the insert search */ list_start_pos = iptcc_bsearch_chain_index(c->name, &i, h); /* Handle the case, where chain.name is smaller than index[0] */ if (i==0 && strcmp(c->name, h->chain_index[0]->name) <= 0) { h->chain_index[0] = c; /* Update chain index head */ list_start_pos = h->chains.next; debug("Update chain_index[0] with %s\n", c->name); } /* Handel if bsearch bails out early */ if (list_start_pos == &h->chains) { list_start_pos = h->chains.next; } /* sort only user defined chains */ if (!c->hooknum) { list_for_each_entry(tmp, list_start_pos->prev, list) { if (!tmp->hooknum && strcmp(c->name, tmp->name) <= 0) { list_add(&c->list, tmp->list.prev); return; } /* Stop if list head is reached */ if (&tmp->list == &h->chains) { debug("Insert, list head reached add to tail\n"); break; } } } /* survived till end of list: add at tail */ list_add_tail(&c->list, &h->chains); } /* Another ugly helper function split out of cache_add_entry to make it less * spaghetti code */ static void __iptcc_p_add_chain(struct xtc_handle *h, struct chain_head *c, unsigned int offset, unsigned int *num) { struct list_head *tail = h->chains.prev; struct chain_head *ctail; __iptcc_p_del_policy(h, *num); c->head_offset = offset; c->index = *num; /* Chains from kernel are already sorted, as they are inserted * sorted. But there exists an issue when shifting to 1.4.0 * from an older version, as old versions allow last created * chain to be unsorted. */ if (iptcc_is_builtin(c)) /* Only user defined chains are sorted*/ list_add_tail(&c->list, &h->chains); else { ctail = list_entry(tail, struct chain_head, list); if (strcmp(c->name, ctail->name) > 0 || iptcc_is_builtin(ctail)) list_add_tail(&c->list, &h->chains);/* Already sorted*/ else { iptc_insert_chain(h, c);/* Was not sorted */ /* Notice, if chains were not received sorted * from kernel, then an offset bsearch is no * longer valid. */ h->sorted_offsets = 0; debug("NOTICE: chain:[%s] was NOT sorted(ctail:%s)\n", c->name, ctail->name); } } h->chain_iterator_cur = c; } /* main parser function: add an entry from the blob to the cache */ static int cache_add_entry(STRUCT_ENTRY *e, struct xtc_handle *h, STRUCT_ENTRY **prev, unsigned int *num) { unsigned int builtin; unsigned int offset = (char *)e - (char *)h->entries->entrytable; DEBUGP("entering..."); /* Last entry ("policy rule"). End it.*/ if (iptcb_entry2offset(h,e) + e->next_offset == h->entries->size) { /* This is the ERROR node at the end of the chain */ DEBUGP_C("%u:%u: end of table:\n", *num, offset); __iptcc_p_del_policy(h, *num); h->chain_iterator_cur = NULL; goto out_inc; } /* We know this is the start of a new chain if it's an ERROR * target, or a hook entry point */ if (strcmp(GET_TARGET(e)->u.user.name, ERROR_TARGET) == 0) { struct chain_head *c = iptcc_alloc_chain_head((const char *)GET_TARGET(e)->data, 0); DEBUGP_C("%u:%u:new userdefined chain %s: %p\n", *num, offset, (char *)c->name, c); if (!c) { errno = -ENOMEM; return -1; } h->num_chains++; /* New user defined chain */ __iptcc_p_add_chain(h, c, offset, num); } else if ((builtin = iptcb_ent_is_hook_entry(e, h)) != 0) { struct chain_head *c = iptcc_alloc_chain_head((char *)hooknames[builtin-1], builtin); DEBUGP_C("%u:%u new builtin chain: %p (rules=%p)\n", *num, offset, c, &c->rules); if (!c) { errno = -ENOMEM; return -1; } c->hooknum = builtin; __iptcc_p_add_chain(h, c, offset, num); /* FIXME: this is ugly. */ goto new_rule; } else { /* has to be normal rule */ struct rule_head *r; new_rule: if (!(r = iptcc_alloc_rule(h->chain_iterator_cur, e->next_offset))) { errno = ENOMEM; return -1; } DEBUGP_C("%u:%u normal rule: %p: ", *num, offset, r); r->index = *num; r->offset = offset; memcpy(r->entry, e, e->next_offset); r->counter_map.maptype = COUNTER_MAP_NORMAL_MAP; r->counter_map.mappos = r->index; /* handling of jumps, etc. */ if (!strcmp(GET_TARGET(e)->u.user.name, STANDARD_TARGET)) { STRUCT_STANDARD_TARGET *t; t = (STRUCT_STANDARD_TARGET *)GET_TARGET(e); if (t->target.u.target_size != ALIGN(sizeof(STRUCT_STANDARD_TARGET))) { errno = EINVAL; free(r); return -1; } if (t->verdict < 0) { DEBUGP_C("standard, verdict=%d\n", t->verdict); r->type = IPTCC_R_STANDARD; } else if (t->verdict == r->offset+e->next_offset) { DEBUGP_C("fallthrough\n"); r->type = IPTCC_R_FALLTHROUGH; } else { DEBUGP_C("jump, target=%u\n", t->verdict); r->type = IPTCC_R_JUMP; /* Jump target fixup has to be deferred * until second pass, since we migh not * yet have parsed the target */ } } else { DEBUGP_C("module, target=%s\n", GET_TARGET(e)->u.user.name); r->type = IPTCC_R_MODULE; } list_add_tail(&r->list, &h->chain_iterator_cur->rules); h->chain_iterator_cur->num_rules++; } out_inc: (*num)++; return 0; } /* parse an iptables blob into it's pieces */ static int parse_table(struct xtc_handle *h) { STRUCT_ENTRY *prev; unsigned int num = 0; struct chain_head *c; /* Assume that chains offsets are sorted, this verified during parsing of ruleset (in __iptcc_p_add_chain())*/ h->sorted_offsets = 1; /* First pass: over ruleset blob */ ENTRY_ITERATE(h->entries->entrytable, h->entries->size, cache_add_entry, h, &prev, &num); /* Build the chain index, used for chain list search speedup */ if ((iptcc_chain_index_alloc(h)) < 0) return -ENOMEM; iptcc_chain_index_build(h); /* Second pass: fixup parsed data from first pass */ list_for_each_entry(c, &h->chains, list) { struct rule_head *r; list_for_each_entry(r, &c->rules, list) { struct chain_head *lc; STRUCT_STANDARD_TARGET *t; if (r->type != IPTCC_R_JUMP) continue; t = (STRUCT_STANDARD_TARGET *)GET_TARGET(r->entry); lc = iptcc_find_chain_by_offset(h, t->verdict); if (!lc) return -1; r->jump = lc; lc->references++; } } return 1; } /********************************************************************** * RULESET COMPILATION (cache -> blob) **********************************************************************/ /* Convenience structures */ struct iptcb_chain_start{ STRUCT_ENTRY e; struct xt_error_target name; }; #define IPTCB_CHAIN_START_SIZE (sizeof(STRUCT_ENTRY) + \ ALIGN(sizeof(struct xt_error_target))) struct iptcb_chain_foot { STRUCT_ENTRY e; STRUCT_STANDARD_TARGET target; }; #define IPTCB_CHAIN_FOOT_SIZE (sizeof(STRUCT_ENTRY) + \ ALIGN(sizeof(STRUCT_STANDARD_TARGET))) struct iptcb_chain_error { STRUCT_ENTRY entry; struct xt_error_target target; }; #define IPTCB_CHAIN_ERROR_SIZE (sizeof(STRUCT_ENTRY) + \ ALIGN(sizeof(struct xt_error_target))) /* compile rule from cache into blob */ static inline int iptcc_compile_rule (struct xtc_handle *h, STRUCT_REPLACE *repl, struct rule_head *r) { /* handle jumps */ if (r->type == IPTCC_R_JUMP) { STRUCT_STANDARD_TARGET *t; t = (STRUCT_STANDARD_TARGET *)GET_TARGET(r->entry); /* memset for memcmp convenience on delete/replace */ memset(t->target.u.user.name, 0, FUNCTION_MAXNAMELEN); strcpy(t->target.u.user.name, STANDARD_TARGET); /* Jumps can only happen to builtin chains, so we * can safely assume that they always have a header */ t->verdict = r->jump->head_offset + IPTCB_CHAIN_START_SIZE; } else if (r->type == IPTCC_R_FALLTHROUGH) { STRUCT_STANDARD_TARGET *t; t = (STRUCT_STANDARD_TARGET *)GET_TARGET(r->entry); t->verdict = r->offset + r->size; } /* copy entry from cache to blob */ memcpy((char *)repl->entries+r->offset, r->entry, r->size); return 1; } /* compile chain from cache into blob */ static int iptcc_compile_chain(struct xtc_handle *h, STRUCT_REPLACE *repl, struct chain_head *c) { int ret; struct rule_head *r; struct iptcb_chain_start *head; struct iptcb_chain_foot *foot; /* only user-defined chains have heaer */ if (!iptcc_is_builtin(c)) { /* put chain header in place */ head = (void *)repl->entries + c->head_offset; head->e.target_offset = sizeof(STRUCT_ENTRY); head->e.next_offset = IPTCB_CHAIN_START_SIZE; strcpy(head->name.target.u.user.name, ERROR_TARGET); head->name.target.u.target_size = ALIGN(sizeof(struct xt_error_target)); strcpy(head->name.errorname, c->name); } else { repl->hook_entry[c->hooknum-1] = c->head_offset; repl->underflow[c->hooknum-1] = c->foot_offset; } /* iterate over rules */ list_for_each_entry(r, &c->rules, list) { ret = iptcc_compile_rule(h, repl, r); if (ret < 0) return ret; } /* put chain footer in place */ foot = (void *)repl->entries + c->foot_offset; foot->e.target_offset = sizeof(STRUCT_ENTRY); foot->e.next_offset = IPTCB_CHAIN_FOOT_SIZE; strcpy(foot->target.target.u.user.name, STANDARD_TARGET); foot->target.target.u.target_size = ALIGN(sizeof(STRUCT_STANDARD_TARGET)); /* builtin targets have verdict, others return */ if (iptcc_is_builtin(c)) foot->target.verdict = c->verdict; else foot->target.verdict = RETURN; /* set policy-counters */ memcpy(&foot->e.counters, &c->counters, sizeof(STRUCT_COUNTERS)); return 0; } /* calculate offset and number for every rule in the cache */ static int iptcc_compile_chain_offsets(struct xtc_handle *h, struct chain_head *c, unsigned int *offset, unsigned int *num) { struct rule_head *r; c->head_offset = *offset; DEBUGP("%s: chain_head %u, offset=%u\n", c->name, *num, *offset); if (!iptcc_is_builtin(c)) { /* Chain has header */ *offset += sizeof(STRUCT_ENTRY) + ALIGN(sizeof(struct xt_error_target)); (*num)++; } list_for_each_entry(r, &c->rules, list) { DEBUGP("rule %u, offset=%u, index=%u\n", *num, *offset, *num); r->offset = *offset; r->index = *num; *offset += r->size; (*num)++; } DEBUGP("%s; chain_foot %u, offset=%u, index=%u\n", c->name, *num, *offset, *num); c->foot_offset = *offset; c->foot_index = *num; *offset += sizeof(STRUCT_ENTRY) + ALIGN(sizeof(STRUCT_STANDARD_TARGET)); (*num)++; return 1; } /* put the pieces back together again */ static int iptcc_compile_table_prep(struct xtc_handle *h, unsigned int *size) { struct chain_head *c; unsigned int offset = 0, num = 0; int ret = 0; /* First pass: calculate offset for every rule */ list_for_each_entry(c, &h->chains, list) { ret = iptcc_compile_chain_offsets(h, c, &offset, &num); if (ret < 0) return ret; } /* Append one error rule at end of chain */ num++; offset += sizeof(STRUCT_ENTRY) + ALIGN(sizeof(struct xt_error_target)); /* ruleset size is now in offset */ *size = offset; return num; } static int iptcc_compile_table(struct xtc_handle *h, STRUCT_REPLACE *repl) { struct chain_head *c; struct iptcb_chain_error *error; /* Second pass: copy from cache to offsets, fill in jumps */ list_for_each_entry(c, &h->chains, list) { int ret = iptcc_compile_chain(h, repl, c); if (ret < 0) return ret; } /* Append error rule at end of chain */ error = (void *)repl->entries + repl->size - IPTCB_CHAIN_ERROR_SIZE; error->entry.target_offset = sizeof(STRUCT_ENTRY); error->entry.next_offset = IPTCB_CHAIN_ERROR_SIZE; error->target.target.u.user.target_size = ALIGN(sizeof(struct xt_error_target)); strcpy((char *)&error->target.target.u.user.name, ERROR_TARGET); strcpy((char *)&error->target.errorname, "ERROR"); return 1; } /********************************************************************** * EXTERNAL API (operates on cache only) **********************************************************************/ /* Allocate handle of given size */ static struct xtc_handle * alloc_handle(const char *tablename, unsigned int size, unsigned int num_rules) { struct xtc_handle *h; h = malloc(sizeof(*h)); if (!h) { errno = ENOMEM; return NULL; } memset(h, 0, sizeof(*h)); INIT_LIST_HEAD(&h->chains); strcpy(h->info.name, tablename); h->entries = malloc(sizeof(STRUCT_GET_ENTRIES) + size); if (!h->entries) goto out_free_handle; strcpy(h->entries->name, tablename); h->entries->size = size; return h; out_free_handle: free(h); return NULL; } struct xtc_handle * TC_INIT(const char *tablename) { struct xtc_handle *h; STRUCT_GETINFO info; unsigned int tmp; socklen_t s; int sockfd; retry: iptc_fn = TC_INIT; if (strlen(tablename) >= TABLE_MAXNAMELEN) { errno = EINVAL; return NULL; } sockfd = socket(TC_AF, SOCK_RAW, IPPROTO_RAW); if (sockfd < 0) return NULL; if (fcntl(sockfd, F_SETFD, FD_CLOEXEC) == -1) { fprintf(stderr, "Could not set close on exec: %s\n", strerror(errno)); abort(); } s = sizeof(info); strcpy(info.name, tablename); if (getsockopt(sockfd, TC_IPPROTO, SO_GET_INFO, &info, &s) < 0) { close(sockfd); return NULL; } DEBUGP("valid_hooks=0x%08x, num_entries=%u, size=%u\n", info.valid_hooks, info.num_entries, info.size); if ((h = alloc_handle(info.name, info.size, info.num_entries)) == NULL) { close(sockfd); return NULL; } /* Initialize current state */ h->sockfd = sockfd; h->info = info; h->entries->size = h->info.size; tmp = sizeof(STRUCT_GET_ENTRIES) + h->info.size; if (getsockopt(h->sockfd, TC_IPPROTO, SO_GET_ENTRIES, h->entries, &tmp) < 0) goto error; #ifdef IPTC_DEBUG2 { int fd = open("/tmp/libiptc-so_get_entries.blob", O_CREAT|O_WRONLY, 0644); if (fd >= 0) { write(fd, h->entries, tmp); close(fd); } } #endif if (parse_table(h) < 0) goto error; CHECK(h); return h; error: TC_FREE(h); /* A different process changed the ruleset size, retry */ if (errno == EAGAIN) goto retry; return NULL; } void TC_FREE(struct xtc_handle *h) { struct chain_head *c, *tmp; iptc_fn = TC_FREE; close(h->sockfd); list_for_each_entry_safe(c, tmp, &h->chains, list) { struct rule_head *r, *rtmp; list_for_each_entry_safe(r, rtmp, &c->rules, list) { free(r); } free(c); } iptcc_chain_index_free(h); free(h->entries); free(h); } static inline int print_match(const STRUCT_ENTRY_MATCH *m) { printf("Match name: `%s'\n", m->u.user.name); return 0; } static int dump_entry(STRUCT_ENTRY *e, struct xtc_handle *const handle); void TC_DUMP_ENTRIES(struct xtc_handle *const handle) { iptc_fn = TC_DUMP_ENTRIES; CHECK(handle); printf("libiptc v%s. %u bytes.\n", XTABLES_VERSION, handle->entries->size); printf("Table `%s'\n", handle->info.name); printf("Hooks: pre/in/fwd/out/post = %x/%x/%x/%x/%x\n", handle->info.hook_entry[HOOK_PRE_ROUTING], handle->info.hook_entry[HOOK_LOCAL_IN], handle->info.hook_entry[HOOK_FORWARD], handle->info.hook_entry[HOOK_LOCAL_OUT], handle->info.hook_entry[HOOK_POST_ROUTING]); printf("Underflows: pre/in/fwd/out/post = %x/%x/%x/%x/%x\n", handle->info.underflow[HOOK_PRE_ROUTING], handle->info.underflow[HOOK_LOCAL_IN], handle->info.underflow[HOOK_FORWARD], handle->info.underflow[HOOK_LOCAL_OUT], handle->info.underflow[HOOK_POST_ROUTING]); ENTRY_ITERATE(handle->entries->entrytable, handle->entries->size, dump_entry, handle); } /* Does this chain exist? */ int TC_IS_CHAIN(const char *chain, struct xtc_handle *const handle) { iptc_fn = TC_IS_CHAIN; return iptcc_find_label(chain, handle) != NULL; } static void iptcc_chain_iterator_advance(struct xtc_handle *handle) { struct chain_head *c = handle->chain_iterator_cur; if (c->list.next == &handle->chains) handle->chain_iterator_cur = NULL; else handle->chain_iterator_cur = list_entry(c->list.next, struct chain_head, list); } /* Iterator functions to run through the chains. */ const char * TC_FIRST_CHAIN(struct xtc_handle *handle) { struct chain_head *c = list_entry(handle->chains.next, struct chain_head, list); iptc_fn = TC_FIRST_CHAIN; if (list_empty(&handle->chains)) { DEBUGP(": no chains\n"); return NULL; } handle->chain_iterator_cur = c; iptcc_chain_iterator_advance(handle); DEBUGP(": returning `%s'\n", c->name); return c->name; } /* Iterator functions to run through the chains. Returns NULL at end. */ const char * TC_NEXT_CHAIN(struct xtc_handle *handle) { struct chain_head *c = handle->chain_iterator_cur; iptc_fn = TC_NEXT_CHAIN; if (!c) { DEBUGP(": no more chains\n"); return NULL; } iptcc_chain_iterator_advance(handle); DEBUGP(": returning `%s'\n", c->name); return c->name; } /* Get first rule in the given chain: NULL for empty chain. */ const STRUCT_ENTRY * TC_FIRST_RULE(const char *chain, struct xtc_handle *handle) { struct chain_head *c; struct rule_head *r; iptc_fn = TC_FIRST_RULE; DEBUGP("first rule(%s): ", chain); c = iptcc_find_label(chain, handle); if (!c) { errno = ENOENT; return NULL; } /* Empty chain: single return/policy rule */ if (list_empty(&c->rules)) { DEBUGP_C("no rules, returning NULL\n"); return NULL; } r = list_entry(c->rules.next, struct rule_head, list); handle->rule_iterator_cur = r; DEBUGP_C("%p\n", r); return r->entry; } /* Returns NULL when rules run out. */ const STRUCT_ENTRY * TC_NEXT_RULE(const STRUCT_ENTRY *prev, struct xtc_handle *handle) { struct rule_head *r; iptc_fn = TC_NEXT_RULE; DEBUGP("rule_iterator_cur=%p...", handle->rule_iterator_cur); if (handle->rule_iterator_cur == NULL) { DEBUGP_C("returning NULL\n"); return NULL; } r = list_entry(handle->rule_iterator_cur->list.next, struct rule_head, list); iptc_fn = TC_NEXT_RULE; DEBUGP_C("next=%p, head=%p...", &r->list, &handle->rule_iterator_cur->chain->rules); if (&r->list == &handle->rule_iterator_cur->chain->rules) { handle->rule_iterator_cur = NULL; DEBUGP_C("finished, returning NULL\n"); return NULL; } handle->rule_iterator_cur = r; /* NOTE: prev is without any influence ! */ DEBUGP_C("returning rule %p\n", r); return r->entry; } /* Returns a pointer to the target name of this position. */ static const char *standard_target_map(int verdict) { switch (verdict) { case RETURN: return LABEL_RETURN; break; case -NF_ACCEPT-1: return LABEL_ACCEPT; break; case -NF_DROP-1: return LABEL_DROP; break; case -NF_QUEUE-1: return LABEL_QUEUE; break; default: fprintf(stderr, "ERROR: %d not a valid target)\n", verdict); abort(); break; } /* not reached */ return NULL; } /* Returns a pointer to the target name of this position. */ const char *TC_GET_TARGET(const STRUCT_ENTRY *ce, struct xtc_handle *handle) { STRUCT_ENTRY *e = (STRUCT_ENTRY *)ce; struct rule_head *r = container_of(e, struct rule_head, entry[0]); const unsigned char *data; iptc_fn = TC_GET_TARGET; switch(r->type) { int spos; case IPTCC_R_FALLTHROUGH: return ""; break; case IPTCC_R_JUMP: DEBUGP("r=%p, jump=%p, name=`%s'\n", r, r->jump, r->jump->name); return r->jump->name; break; case IPTCC_R_STANDARD: data = GET_TARGET(e)->data; spos = *(const int *)data; DEBUGP("r=%p, spos=%d'\n", r, spos); return standard_target_map(spos); break; case IPTCC_R_MODULE: return GET_TARGET(e)->u.user.name; break; } return NULL; } /* Is this a built-in chain? Actually returns hook + 1. */ int TC_BUILTIN(const char *chain, struct xtc_handle *const handle) { struct chain_head *c; iptc_fn = TC_BUILTIN; c = iptcc_find_label(chain, handle); if (!c) { errno = ENOENT; return 0; } return iptcc_is_builtin(c); } /* Get the policy of a given built-in chain */ const char * TC_GET_POLICY(const char *chain, STRUCT_COUNTERS *counters, struct xtc_handle *handle) { struct chain_head *c; iptc_fn = TC_GET_POLICY; DEBUGP("called for chain %s\n", chain); c = iptcc_find_label(chain, handle); if (!c) { errno = ENOENT; return NULL; } if (!iptcc_is_builtin(c)) return NULL; *counters = c->counters; return standard_target_map(c->verdict); } static int iptcc_standard_map(struct rule_head *r, int verdict) { STRUCT_ENTRY *e = r->entry; STRUCT_STANDARD_TARGET *t; t = (STRUCT_STANDARD_TARGET *)GET_TARGET(e); if (t->target.u.target_size != ALIGN(sizeof(STRUCT_STANDARD_TARGET))) { errno = EINVAL; return 0; } /* memset for memcmp convenience on delete/replace */ memset(t->target.u.user.name, 0, FUNCTION_MAXNAMELEN); strcpy(t->target.u.user.name, STANDARD_TARGET); t->verdict = verdict; r->type = IPTCC_R_STANDARD; return 1; } static int iptcc_map_target(struct xtc_handle *const handle, struct rule_head *r) { STRUCT_ENTRY *e = r->entry; STRUCT_ENTRY_TARGET *t = GET_TARGET(e); /* Maybe it's empty (=> fall through) */ if (strcmp(t->u.user.name, "") == 0) { r->type = IPTCC_R_FALLTHROUGH; return 1; } /* Maybe it's a standard target name... */ else if (strcmp(t->u.user.name, LABEL_ACCEPT) == 0) return iptcc_standard_map(r, -NF_ACCEPT - 1); else if (strcmp(t->u.user.name, LABEL_DROP) == 0) return iptcc_standard_map(r, -NF_DROP - 1); else if (strcmp(t->u.user.name, LABEL_QUEUE) == 0) return iptcc_standard_map(r, -NF_QUEUE - 1); else if (strcmp(t->u.user.name, LABEL_RETURN) == 0) return iptcc_standard_map(r, RETURN); else if (TC_BUILTIN(t->u.user.name, handle)) { /* Can't jump to builtins. */ errno = EINVAL; return 0; } else { /* Maybe it's an existing chain name. */ struct chain_head *c; DEBUGP("trying to find chain `%s': ", t->u.user.name); c = iptcc_find_label(t->u.user.name, handle); if (c) { DEBUGP_C("found!\n"); r->type = IPTCC_R_JUMP; r->jump = c; c->references++; return 1; } DEBUGP_C("not found :(\n"); } /* Must be a module? If not, kernel will reject... */ /* memset to all 0 for your memcmp convenience: don't clear version */ memset(t->u.user.name + strlen(t->u.user.name), 0, FUNCTION_MAXNAMELEN - 1 - strlen(t->u.user.name)); r->type = IPTCC_R_MODULE; set_changed(handle); return 1; } /* Insert the entry `fw' in chain `chain' into position `rulenum'. */ int TC_INSERT_ENTRY(const IPT_CHAINLABEL chain, const STRUCT_ENTRY *e, unsigned int rulenum, struct xtc_handle *handle) { struct chain_head *c; struct rule_head *r; struct list_head *prev; iptc_fn = TC_INSERT_ENTRY; if (!(c = iptcc_find_label(chain, handle))) { errno = ENOENT; return 0; } /* first rulenum index = 0 first c->num_rules index = 1 */ if (rulenum > c->num_rules) { errno = E2BIG; return 0; } /* If we are inserting at the end just take advantage of the double linked list, insert will happen before the entry prev points to. */ if (rulenum == c->num_rules) { prev = &c->rules; } else if (rulenum + 1 <= c->num_rules/2) { r = iptcc_get_rule_num(c, rulenum + 1); prev = &r->list; } else { r = iptcc_get_rule_num_reverse(c, c->num_rules - rulenum); prev = &r->list; } if (!(r = iptcc_alloc_rule(c, e->next_offset))) { errno = ENOMEM; return 0; } memcpy(r->entry, e, e->next_offset); r->counter_map.maptype = COUNTER_MAP_SET; if (!iptcc_map_target(handle, r)) { free(r); return 0; } list_add_tail(&r->list, prev); c->num_rules++; set_changed(handle); return 1; } /* Atomically replace rule `rulenum' in `chain' with `fw'. */ int TC_REPLACE_ENTRY(const IPT_CHAINLABEL chain, const STRUCT_ENTRY *e, unsigned int rulenum, struct xtc_handle *handle) { struct chain_head *c; struct rule_head *r, *old; iptc_fn = TC_REPLACE_ENTRY; if (!(c = iptcc_find_label(chain, handle))) { errno = ENOENT; return 0; } if (rulenum >= c->num_rules) { errno = E2BIG; return 0; } /* Take advantage of the double linked list if possible. */ if (rulenum + 1 <= c->num_rules/2) { old = iptcc_get_rule_num(c, rulenum + 1); } else { old = iptcc_get_rule_num_reverse(c, c->num_rules - rulenum); } if (!(r = iptcc_alloc_rule(c, e->next_offset))) { errno = ENOMEM; return 0; } memcpy(r->entry, e, e->next_offset); r->counter_map.maptype = COUNTER_MAP_SET; if (!iptcc_map_target(handle, r)) { free(r); return 0; } list_add(&r->list, &old->list); iptcc_delete_rule(old); set_changed(handle); return 1; } /* Append entry `fw' to chain `chain'. Equivalent to insert with rulenum = length of chain. */ int TC_APPEND_ENTRY(const IPT_CHAINLABEL chain, const STRUCT_ENTRY *e, struct xtc_handle *handle) { struct chain_head *c; struct rule_head *r; iptc_fn = TC_APPEND_ENTRY; if (!(c = iptcc_find_label(chain, handle))) { DEBUGP("unable to find chain `%s'\n", chain); errno = ENOENT; return 0; } if (!(r = iptcc_alloc_rule(c, e->next_offset))) { DEBUGP("unable to allocate rule for chain `%s'\n", chain); errno = ENOMEM; return 0; } memcpy(r->entry, e, e->next_offset); r->counter_map.maptype = COUNTER_MAP_SET; if (!iptcc_map_target(handle, r)) { DEBUGP("unable to map target of rule for chain `%s'\n", chain); free(r); return 0; } list_add_tail(&r->list, &c->rules); c->num_rules++; set_changed(handle); return 1; } static inline int match_different(const STRUCT_ENTRY_MATCH *a, const unsigned char *a_elems, const unsigned char *b_elems, unsigned char **maskptr) { const STRUCT_ENTRY_MATCH *b; unsigned int i; /* Offset of b is the same as a. */ b = (void *)b_elems + ((unsigned char *)a - a_elems); if (a->u.match_size != b->u.match_size) return 1; if (strcmp(a->u.user.name, b->u.user.name) != 0) return 1; *maskptr += ALIGN(sizeof(*a)); for (i = 0; i < a->u.match_size - ALIGN(sizeof(*a)); i++) if (((a->data[i] ^ b->data[i]) & (*maskptr)[i]) != 0) return 1; *maskptr += i; return 0; } static inline int target_same(struct rule_head *a, struct rule_head *b,const unsigned char *mask) { unsigned int i; STRUCT_ENTRY_TARGET *ta, *tb; if (a->type != b->type) return 0; ta = GET_TARGET(a->entry); tb = GET_TARGET(b->entry); switch (a->type) { case IPTCC_R_FALLTHROUGH: return 1; case IPTCC_R_JUMP: return a->jump == b->jump; case IPTCC_R_STANDARD: return ((STRUCT_STANDARD_TARGET *)ta)->verdict == ((STRUCT_STANDARD_TARGET *)tb)->verdict; case IPTCC_R_MODULE: if (ta->u.target_size != tb->u.target_size) return 0; if (strcmp(ta->u.user.name, tb->u.user.name) != 0) return 0; for (i = 0; i < ta->u.target_size - sizeof(*ta); i++) if (((ta->data[i] ^ tb->data[i]) & mask[i]) != 0) return 0; return 1; default: fprintf(stderr, "ERROR: bad type %i\n", a->type); abort(); } } static unsigned char * is_same(const STRUCT_ENTRY *a, const STRUCT_ENTRY *b, unsigned char *matchmask); /* find the first rule in `chain' which matches `fw' and remove it unless dry_run is set */ static int delete_entry(const IPT_CHAINLABEL chain, const STRUCT_ENTRY *origfw, unsigned char *matchmask, struct xtc_handle *handle, bool dry_run) { struct chain_head *c; struct rule_head *r, *i; iptc_fn = TC_DELETE_ENTRY; if (!(c = iptcc_find_label(chain, handle))) { errno = ENOENT; return 0; } /* Create a rule_head from origfw. */ r = iptcc_alloc_rule(c, origfw->next_offset); if (!r) { errno = ENOMEM; return 0; } memcpy(r->entry, origfw, origfw->next_offset); r->counter_map.maptype = COUNTER_MAP_NOMAP; if (!iptcc_map_target(handle, r)) { DEBUGP("unable to map target of rule for chain `%s'\n", chain); free(r); return 0; } else { /* iptcc_map_target increment target chain references * since this is a fake rule only used for matching * the chain references count is decremented again. */ if (r->type == IPTCC_R_JUMP && r->jump) r->jump->references--; } list_for_each_entry(i, &c->rules, list) { unsigned char *mask; mask = is_same(r->entry, i->entry, matchmask); if (!mask) continue; if (!target_same(r, i, mask)) continue; /* if we are just doing a dry run, we simply skip the rest */ if (dry_run){ free(r); return 1; } /* If we are about to delete the rule that is the * current iterator, move rule iterator back. next * pointer will then point to real next node */ if (i == handle->rule_iterator_cur) { handle->rule_iterator_cur = list_entry(handle->rule_iterator_cur->list.prev, struct rule_head, list); } c->num_rules--; iptcc_delete_rule(i); set_changed(handle); free(r); return 1; } free(r); errno = ENOENT; return 0; } /* check whether a specified rule is present */ int TC_CHECK_ENTRY(const IPT_CHAINLABEL chain, const STRUCT_ENTRY *origfw, unsigned char *matchmask, struct xtc_handle *handle) { /* do a dry-run delete to find out whether a matching rule exists */ return delete_entry(chain, origfw, matchmask, handle, true); } /* Delete the first rule in `chain' which matches `fw'. */ int TC_DELETE_ENTRY(const IPT_CHAINLABEL chain, const STRUCT_ENTRY *origfw, unsigned char *matchmask, struct xtc_handle *handle) { return delete_entry(chain, origfw, matchmask, handle, false); } /* Delete the rule in position `rulenum' in `chain'. */ int TC_DELETE_NUM_ENTRY(const IPT_CHAINLABEL chain, unsigned int rulenum, struct xtc_handle *handle) { struct chain_head *c; struct rule_head *r; iptc_fn = TC_DELETE_NUM_ENTRY; if (!(c = iptcc_find_label(chain, handle))) { errno = ENOENT; return 0; } if (rulenum >= c->num_rules) { errno = E2BIG; return 0; } /* Take advantage of the double linked list if possible. */ if (rulenum + 1 <= c->num_rules/2) { r = iptcc_get_rule_num(c, rulenum + 1); } else { r = iptcc_get_rule_num_reverse(c, c->num_rules - rulenum); } /* If we are about to delete the rule that is the current * iterator, move rule iterator back. next pointer will then * point to real next node */ if (r == handle->rule_iterator_cur) { handle->rule_iterator_cur = list_entry(handle->rule_iterator_cur->list.prev, struct rule_head, list); } c->num_rules--; iptcc_delete_rule(r); set_changed(handle); return 1; } /* Flushes the entries in the given chain (ie. empties chain). */ int TC_FLUSH_ENTRIES(const IPT_CHAINLABEL chain, struct xtc_handle *handle) { struct chain_head *c; struct rule_head *r, *tmp; iptc_fn = TC_FLUSH_ENTRIES; if (!(c = iptcc_find_label(chain, handle))) { errno = ENOENT; return 0; } list_for_each_entry_safe(r, tmp, &c->rules, list) { iptcc_delete_rule(r); } c->num_rules = 0; set_changed(handle); return 1; } /* Zeroes the counters in a chain. */ int TC_ZERO_ENTRIES(const IPT_CHAINLABEL chain, struct xtc_handle *handle) { struct chain_head *c; struct rule_head *r; iptc_fn = TC_ZERO_ENTRIES; if (!(c = iptcc_find_label(chain, handle))) { errno = ENOENT; return 0; } if (c->counter_map.maptype == COUNTER_MAP_NORMAL_MAP) c->counter_map.maptype = COUNTER_MAP_ZEROED; list_for_each_entry(r, &c->rules, list) { if (r->counter_map.maptype == COUNTER_MAP_NORMAL_MAP) r->counter_map.maptype = COUNTER_MAP_ZEROED; } set_changed(handle); return 1; } STRUCT_COUNTERS * TC_READ_COUNTER(const IPT_CHAINLABEL chain, unsigned int rulenum, struct xtc_handle *handle) { struct chain_head *c; struct rule_head *r; iptc_fn = TC_READ_COUNTER; CHECK(*handle); if (!(c = iptcc_find_label(chain, handle))) { errno = ENOENT; return NULL; } if (!(r = iptcc_get_rule_num(c, rulenum))) { errno = E2BIG; return NULL; } return &r->entry[0].counters; } int TC_ZERO_COUNTER(const IPT_CHAINLABEL chain, unsigned int rulenum, struct xtc_handle *handle) { struct chain_head *c; struct rule_head *r; iptc_fn = TC_ZERO_COUNTER; CHECK(handle); if (!(c = iptcc_find_label(chain, handle))) { errno = ENOENT; return 0; } if (!(r = iptcc_get_rule_num(c, rulenum))) { errno = E2BIG; return 0; } if (r->counter_map.maptype == COUNTER_MAP_NORMAL_MAP) r->counter_map.maptype = COUNTER_MAP_ZEROED; set_changed(handle); return 1; } int TC_SET_COUNTER(const IPT_CHAINLABEL chain, unsigned int rulenum, STRUCT_COUNTERS *counters, struct xtc_handle *handle) { struct chain_head *c; struct rule_head *r; STRUCT_ENTRY *e; iptc_fn = TC_SET_COUNTER; CHECK(handle); if (!(c = iptcc_find_label(chain, handle))) { errno = ENOENT; return 0; } if (!(r = iptcc_get_rule_num(c, rulenum))) { errno = E2BIG; return 0; } e = r->entry; r->counter_map.maptype = COUNTER_MAP_SET; memcpy(&e->counters, counters, sizeof(STRUCT_COUNTERS)); set_changed(handle); return 1; } /* Creates a new chain. */ /* To create a chain, create two rules: error node and unconditional * return. */ int TC_CREATE_CHAIN(const IPT_CHAINLABEL chain, struct xtc_handle *handle) { static struct chain_head *c; int capacity; int exceeded; iptc_fn = TC_CREATE_CHAIN; /* find_label doesn't cover built-in targets: DROP, ACCEPT, QUEUE, RETURN. */ if (iptcc_find_label(chain, handle) || strcmp(chain, LABEL_DROP) == 0 || strcmp(chain, LABEL_ACCEPT) == 0 || strcmp(chain, LABEL_QUEUE) == 0 || strcmp(chain, LABEL_RETURN) == 0) { DEBUGP("Chain `%s' already exists\n", chain); errno = EEXIST; return 0; } if (strlen(chain)+1 > sizeof(IPT_CHAINLABEL)) { DEBUGP("Chain name `%s' too long\n", chain); errno = EINVAL; return 0; } c = iptcc_alloc_chain_head(chain, 0); if (!c) { DEBUGP("Cannot allocate memory for chain `%s'\n", chain); errno = ENOMEM; return 0; } handle->num_chains++; /* New user defined chain */ DEBUGP("Creating chain `%s'\n", chain); iptc_insert_chain(handle, c); /* Insert sorted */ /* Inserting chains don't change the correctness of the chain * index (except if its smaller than index[0], but that * handled by iptc_insert_chain). It only causes longer lists * in the buckets. Thus, only rebuild chain index when the * capacity is exceed with CHAIN_INDEX_INSERT_MAX chains. */ capacity = handle->chain_index_sz * CHAIN_INDEX_BUCKET_LEN; exceeded = handle->num_chains - capacity; if (exceeded > CHAIN_INDEX_INSERT_MAX) { debug("Capacity(%d) exceeded(%d) rebuild (chains:%d)\n", capacity, exceeded, handle->num_chains); iptcc_chain_index_rebuild(handle); } set_changed(handle); return 1; } /* Get the number of references to this chain. */ int TC_GET_REFERENCES(unsigned int *ref, const IPT_CHAINLABEL chain, struct xtc_handle *handle) { struct chain_head *c; iptc_fn = TC_GET_REFERENCES; if (!(c = iptcc_find_label(chain, handle))) { errno = ENOENT; return 0; } *ref = c->references; return 1; } /* Deletes a chain. */ int TC_DELETE_CHAIN(const IPT_CHAINLABEL chain, struct xtc_handle *handle) { unsigned int references; struct chain_head *c; iptc_fn = TC_DELETE_CHAIN; if (!(c = iptcc_find_label(chain, handle))) { DEBUGP("cannot find chain `%s'\n", chain); errno = ENOENT; return 0; } if (TC_BUILTIN(chain, handle)) { DEBUGP("cannot remove builtin chain `%s'\n", chain); errno = EINVAL; return 0; } if (!TC_GET_REFERENCES(&references, chain, handle)) { DEBUGP("cannot get references on chain `%s'\n", chain); return 0; } if (references > 0) { DEBUGP("chain `%s' still has references\n", chain); errno = EMLINK; return 0; } if (c->num_rules) { DEBUGP("chain `%s' is not empty\n", chain); errno = ENOTEMPTY; return 0; } /* If we are about to delete the chain that is the current * iterator, move chain iterator forward. */ if (c == handle->chain_iterator_cur) iptcc_chain_iterator_advance(handle); handle->num_chains--; /* One user defined chain deleted */ //list_del(&c->list); /* Done in iptcc_chain_index_delete_chain() */ iptcc_chain_index_delete_chain(c, handle); free(c); DEBUGP("chain `%s' deleted\n", chain); set_changed(handle); return 1; } /* Renames a chain. */ int TC_RENAME_CHAIN(const IPT_CHAINLABEL oldname, const IPT_CHAINLABEL newname, struct xtc_handle *handle) { struct chain_head *c; iptc_fn = TC_RENAME_CHAIN; /* find_label doesn't cover built-in targets: DROP, ACCEPT, QUEUE, RETURN. */ if (iptcc_find_label(newname, handle) || strcmp(newname, LABEL_DROP) == 0 || strcmp(newname, LABEL_ACCEPT) == 0 || strcmp(newname, LABEL_QUEUE) == 0 || strcmp(newname, LABEL_RETURN) == 0) { errno = EEXIST; return 0; } if (!(c = iptcc_find_label(oldname, handle)) || TC_BUILTIN(oldname, handle)) { errno = ENOENT; return 0; } if (strlen(newname)+1 > sizeof(IPT_CHAINLABEL)) { errno = EINVAL; return 0; } /* This only unlinks "c" from the list, thus no free(c) */ iptcc_chain_index_delete_chain(c, handle); /* Change the name of the chain */ strncpy(c->name, newname, sizeof(IPT_CHAINLABEL)); /* Insert sorted into to list again */ iptc_insert_chain(handle, c); set_changed(handle); return 1; } /* Sets the policy on a built-in chain. */ int TC_SET_POLICY(const IPT_CHAINLABEL chain, const IPT_CHAINLABEL policy, STRUCT_COUNTERS *counters, struct xtc_handle *handle) { struct chain_head *c; iptc_fn = TC_SET_POLICY; if (!(c = iptcc_find_label(chain, handle))) { DEBUGP("cannot find chain `%s'\n", chain); errno = ENOENT; return 0; } if (!iptcc_is_builtin(c)) { DEBUGP("cannot set policy of userdefinedchain `%s'\n", chain); errno = ENOENT; return 0; } if (strcmp(policy, LABEL_ACCEPT) == 0) c->verdict = -NF_ACCEPT - 1; else if (strcmp(policy, LABEL_DROP) == 0) c->verdict = -NF_DROP - 1; else { errno = EINVAL; return 0; } if (counters) { /* set byte and packet counters */ memcpy(&c->counters, counters, sizeof(STRUCT_COUNTERS)); c->counter_map.maptype = COUNTER_MAP_SET; } else { c->counter_map.maptype = COUNTER_MAP_NOMAP; } set_changed(handle); return 1; } /* Without this, on gcc 2.7.2.3, we get: libiptc.c: In function `TC_COMMIT': libiptc.c:833: fixed or forbidden register was spilled. This may be due to a compiler bug or to impossible asm statements or clauses. */ static void subtract_counters(STRUCT_COUNTERS *answer, const STRUCT_COUNTERS *a, const STRUCT_COUNTERS *b) { answer->pcnt = a->pcnt - b->pcnt; answer->bcnt = a->bcnt - b->bcnt; } static void counters_nomap(STRUCT_COUNTERS_INFO *newcounters, unsigned int idx) { newcounters->counters[idx] = ((STRUCT_COUNTERS) { 0, 0}); DEBUGP_C("NOMAP => zero\n"); } static void counters_normal_map(STRUCT_COUNTERS_INFO *newcounters, STRUCT_REPLACE *repl, unsigned int idx, unsigned int mappos) { /* Original read: X. * Atomic read on replacement: X + Y. * Currently in kernel: Z. * Want in kernel: X + Y + Z. * => Add in X + Y * => Add in replacement read. */ newcounters->counters[idx] = repl->counters[mappos]; DEBUGP_C("NORMAL_MAP => mappos %u \n", mappos); } static void counters_map_zeroed(STRUCT_COUNTERS_INFO *newcounters, STRUCT_REPLACE *repl, unsigned int idx, unsigned int mappos, STRUCT_COUNTERS *counters) { /* Original read: X. * Atomic read on replacement: X + Y. * Currently in kernel: Z. * Want in kernel: Y + Z. * => Add in Y. * => Add in (replacement read - original read). */ subtract_counters(&newcounters->counters[idx], &repl->counters[mappos], counters); DEBUGP_C("ZEROED => mappos %u\n", mappos); } static void counters_map_set(STRUCT_COUNTERS_INFO *newcounters, unsigned int idx, STRUCT_COUNTERS *counters) { /* Want to set counter (iptables-restore) */ memcpy(&newcounters->counters[idx], counters, sizeof(STRUCT_COUNTERS)); DEBUGP_C("SET\n"); } int TC_COMMIT(struct xtc_handle *handle) { /* Replace, then map back the counters. */ STRUCT_REPLACE *repl; STRUCT_COUNTERS_INFO *newcounters; struct chain_head *c; int ret; size_t counterlen; int new_number; unsigned int new_size; iptc_fn = TC_COMMIT; CHECK(*handle); /* Don't commit if nothing changed. */ if (!handle->changed) goto finished; new_number = iptcc_compile_table_prep(handle, &new_size); if (new_number < 0) { errno = ENOMEM; goto out_zero; } repl = malloc(sizeof(*repl) + new_size); if (!repl) { errno = ENOMEM; goto out_zero; } memset(repl, 0, sizeof(*repl) + new_size); #if 0 TC_DUMP_ENTRIES(*handle); #endif counterlen = sizeof(STRUCT_COUNTERS_INFO) + sizeof(STRUCT_COUNTERS) * new_number; /* These are the old counters we will get from kernel */ repl->counters = malloc(sizeof(STRUCT_COUNTERS) * handle->info.num_entries); if (!repl->counters) { errno = ENOMEM; goto out_free_repl; } /* These are the counters we're going to put back, later. */ newcounters = malloc(counterlen); if (!newcounters) { errno = ENOMEM; goto out_free_repl_counters; } memset(newcounters, 0, counterlen); strcpy(repl->name, handle->info.name); repl->num_entries = new_number; repl->size = new_size; repl->num_counters = handle->info.num_entries; repl->valid_hooks = handle->info.valid_hooks; DEBUGP("num_entries=%u, size=%u, num_counters=%u\n", repl->num_entries, repl->size, repl->num_counters); ret = iptcc_compile_table(handle, repl); if (ret < 0) { errno = ret; goto out_free_newcounters; } #ifdef IPTC_DEBUG2 { int fd = open("/tmp/libiptc-so_set_replace.blob", O_CREAT|O_WRONLY, 0644); if (fd >= 0) { write(fd, repl, sizeof(*repl) + repl->size); close(fd); } } #endif ret = setsockopt(handle->sockfd, TC_IPPROTO, SO_SET_REPLACE, repl, sizeof(*repl) + repl->size); if (ret < 0) goto out_free_newcounters; /* Put counters back. */ strcpy(newcounters->name, handle->info.name); newcounters->num_counters = new_number; list_for_each_entry(c, &handle->chains, list) { struct rule_head *r; /* Builtin chains have their own counters */ if (iptcc_is_builtin(c)) { DEBUGP("counter for chain-index %u: ", c->foot_index); switch(c->counter_map.maptype) { case COUNTER_MAP_NOMAP: counters_nomap(newcounters, c->foot_index); break; case COUNTER_MAP_NORMAL_MAP: counters_normal_map(newcounters, repl, c->foot_index, c->counter_map.mappos); break; case COUNTER_MAP_ZEROED: counters_map_zeroed(newcounters, repl, c->foot_index, c->counter_map.mappos, &c->counters); break; case COUNTER_MAP_SET: counters_map_set(newcounters, c->foot_index, &c->counters); break; } } list_for_each_entry(r, &c->rules, list) { DEBUGP("counter for index %u: ", r->index); switch (r->counter_map.maptype) { case COUNTER_MAP_NOMAP: counters_nomap(newcounters, r->index); break; case COUNTER_MAP_NORMAL_MAP: counters_normal_map(newcounters, repl, r->index, r->counter_map.mappos); break; case COUNTER_MAP_ZEROED: counters_map_zeroed(newcounters, repl, r->index, r->counter_map.mappos, &r->entry->counters); break; case COUNTER_MAP_SET: counters_map_set(newcounters, r->index, &r->entry->counters); break; } } } #ifdef IPTC_DEBUG2 { int fd = open("/tmp/libiptc-so_set_add_counters.blob", O_CREAT|O_WRONLY, 0644); if (fd >= 0) { write(fd, newcounters, counterlen); close(fd); } } #endif ret = setsockopt(handle->sockfd, TC_IPPROTO, SO_SET_ADD_COUNTERS, newcounters, counterlen); if (ret < 0) goto out_free_newcounters; free(repl->counters); free(repl); free(newcounters); finished: return 1; out_free_newcounters: free(newcounters); out_free_repl_counters: free(repl->counters); out_free_repl: free(repl); out_zero: return 0; } /* Translates errno numbers into more human-readable form than strerror. */ const char * TC_STRERROR(int err) { unsigned int i; struct table_struct { void *fn; int err; const char *message; } table [] = { { TC_INIT, EPERM, "Permission denied (you must be root)" }, { TC_INIT, EINVAL, "Module is wrong version" }, { TC_INIT, ENOENT, "Table does not exist (do you need to insmod?)" }, { TC_DELETE_CHAIN, ENOTEMPTY, "Chain is not empty" }, { TC_DELETE_CHAIN, EINVAL, "Can't delete built-in chain" }, { TC_DELETE_CHAIN, EMLINK, "Can't delete chain with references left" }, { TC_CREATE_CHAIN, EEXIST, "Chain already exists" }, { TC_INSERT_ENTRY, E2BIG, "Index of insertion too big" }, { TC_REPLACE_ENTRY, E2BIG, "Index of replacement too big" }, { TC_DELETE_NUM_ENTRY, E2BIG, "Index of deletion too big" }, { TC_READ_COUNTER, E2BIG, "Index of counter too big" }, { TC_ZERO_COUNTER, E2BIG, "Index of counter too big" }, { TC_INSERT_ENTRY, ELOOP, "Loop found in table" }, { TC_INSERT_ENTRY, EINVAL, "Target problem" }, /* ENOENT for DELETE probably means no matching rule */ { TC_DELETE_ENTRY, ENOENT, "Bad rule (does a matching rule exist in that chain?)" }, { TC_SET_POLICY, ENOENT, "Bad built-in chain name" }, { TC_SET_POLICY, EINVAL, "Bad policy name" }, { NULL, 0, "Incompatible with this kernel" }, { NULL, ENOPROTOOPT, "iptables who? (do you need to insmod?)" }, { NULL, ENOSYS, "Will be implemented real soon. I promise ;)" }, { NULL, ENOMEM, "Memory allocation problem" }, { NULL, ENOENT, "No chain/target/match by that name" }, }; for (i = 0; i < sizeof(table)/sizeof(struct table_struct); i++) { if ((!table[i].fn || table[i].fn == iptc_fn) && table[i].err == err) return table[i].message; } return strerror(err); } const struct xtc_ops TC_OPS = { .commit = TC_COMMIT, .free = TC_FREE, .builtin = TC_BUILTIN, .is_chain = TC_IS_CHAIN, .flush_entries = TC_FLUSH_ENTRIES, .create_chain = TC_CREATE_CHAIN, .set_policy = TC_SET_POLICY, .strerror = TC_STRERROR, };