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/* Library which manipulates firewall rules. Version 0.1. */
/* 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). */
#include <assert.h>
#include <string.h>
#include <errno.h>
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#ifdef DEBUG_CONNTRACK
#define inline
#endif
#if !defined(__GLIBC__) || (__GLIBC__ < 2)
typedef unsigned int socklen_t;
#endif
#include "libiptc/libiptc.h"
#define IP_VERSION 4
#define IP_OFFSET 0x1FFF
#define HOOK_PRE_ROUTING NF_IP_PRE_ROUTING
#define HOOK_LOCAL_IN NF_IP_LOCAL_IN
#define HOOK_FORWARD NF_IP_FORWARD
#define HOOK_LOCAL_OUT NF_IP_LOCAL_OUT
#define HOOK_POST_ROUTING NF_IP_POST_ROUTING
#define STRUCT_ENTRY_TARGET struct xt_entry_target
#define STRUCT_ENTRY struct ipt_entry
#define STRUCT_ENTRY_MATCH struct xt_entry_match
#define STRUCT_GETINFO struct ipt_getinfo
#define STRUCT_GET_ENTRIES struct ipt_get_entries
#define STRUCT_COUNTERS struct xt_counters
#define STRUCT_COUNTERS_INFO struct xt_counters_info
#define STRUCT_STANDARD_TARGET struct xt_standard_target
#define STRUCT_REPLACE struct ipt_replace
#define ENTRY_ITERATE IPT_ENTRY_ITERATE
#define TABLE_MAXNAMELEN XT_TABLE_MAXNAMELEN
#define FUNCTION_MAXNAMELEN XT_FUNCTION_MAXNAMELEN
#define GET_TARGET ipt_get_target
#define ERROR_TARGET XT_ERROR_TARGET
#define NUMHOOKS NF_IP_NUMHOOKS
#define IPT_CHAINLABEL xt_chainlabel
#define TC_DUMP_ENTRIES dump_entries
#define TC_IS_CHAIN iptc_is_chain
#define TC_FIRST_CHAIN iptc_first_chain
#define TC_NEXT_CHAIN iptc_next_chain
#define TC_FIRST_RULE iptc_first_rule
#define TC_NEXT_RULE iptc_next_rule
#define TC_GET_TARGET iptc_get_target
#define TC_BUILTIN iptc_builtin
#define TC_GET_POLICY iptc_get_policy
#define TC_INSERT_ENTRY iptc_insert_entry
#define TC_REPLACE_ENTRY iptc_replace_entry
#define TC_APPEND_ENTRY iptc_append_entry
#define TC_CHECK_ENTRY iptc_check_entry
#define TC_DELETE_ENTRY iptc_delete_entry
#define TC_DELETE_NUM_ENTRY iptc_delete_num_entry
#define TC_FLUSH_ENTRIES iptc_flush_entries
#define TC_ZERO_ENTRIES iptc_zero_entries
#define TC_READ_COUNTER iptc_read_counter
#define TC_ZERO_COUNTER iptc_zero_counter
#define TC_SET_COUNTER iptc_set_counter
#define TC_CREATE_CHAIN iptc_create_chain
#define TC_GET_REFERENCES iptc_get_references
#define TC_DELETE_CHAIN iptc_delete_chain
#define TC_RENAME_CHAIN iptc_rename_chain
#define TC_SET_POLICY iptc_set_policy
#define TC_GET_RAW_SOCKET iptc_get_raw_socket
#define TC_INIT iptc_init
#define TC_FREE iptc_free
#define TC_COMMIT iptc_commit
#define TC_STRERROR iptc_strerror
#define TC_NUM_RULES iptc_num_rules
#define TC_GET_RULE iptc_get_rule
#define TC_OPS iptc_ops
#define TC_AF AF_INET
#define TC_IPPROTO IPPROTO_IP
#define SO_SET_REPLACE IPT_SO_SET_REPLACE
#define SO_SET_ADD_COUNTERS IPT_SO_SET_ADD_COUNTERS
#define SO_GET_INFO IPT_SO_GET_INFO
#define SO_GET_ENTRIES IPT_SO_GET_ENTRIES
#define SO_GET_VERSION IPT_SO_GET_VERSION
#define STANDARD_TARGET XT_STANDARD_TARGET
#define LABEL_RETURN IPTC_LABEL_RETURN
#define LABEL_ACCEPT IPTC_LABEL_ACCEPT
#define LABEL_DROP IPTC_LABEL_DROP
#define LABEL_QUEUE IPTC_LABEL_QUEUE
#define ALIGN XT_ALIGN
#define RETURN XT_RETURN
#include "libiptc.c"
#define IP_PARTS_NATIVE(n) \
(unsigned int)((n)>>24)&0xFF, \
(unsigned int)((n)>>16)&0xFF, \
(unsigned int)((n)>>8)&0xFF, \
(unsigned int)((n)&0xFF)
#define IP_PARTS(n) IP_PARTS_NATIVE(ntohl(n))
static int
dump_entry(struct ipt_entry *e, struct xtc_handle *const handle)
{
size_t i;
STRUCT_ENTRY_TARGET *t;
printf("Entry %u (%lu):\n", iptcb_entry2index(handle, e),
iptcb_entry2offset(handle, e));
printf("SRC IP: %u.%u.%u.%u/%u.%u.%u.%u\n",
IP_PARTS(e->ip.src.s_addr),IP_PARTS(e->ip.smsk.s_addr));
printf("DST IP: %u.%u.%u.%u/%u.%u.%u.%u\n",
IP_PARTS(e->ip.dst.s_addr),IP_PARTS(e->ip.dmsk.s_addr));
printf("Interface: `%s'/", e->ip.iniface);
for (i = 0; i < IFNAMSIZ; i++)
printf("%c", e->ip.iniface_mask[i] ? 'X' : '.');
printf("to `%s'/", e->ip.outiface);
for (i = 0; i < IFNAMSIZ; i++)
printf("%c", e->ip.outiface_mask[i] ? 'X' : '.');
printf("\nProtocol: %u\n", e->ip.proto);
printf("Flags: %02X\n", e->ip.flags);
printf("Invflags: %02X\n", e->ip.invflags);
printf("Counters: %llu packets, %llu bytes\n",
(unsigned long long)e->counters.pcnt, (unsigned long long)e->counters.bcnt);
printf("Cache: %08X\n", e->nfcache);
IPT_MATCH_ITERATE(e, print_match);
t = GET_TARGET(e);
printf("Target name: `%s' [%u]\n", t->u.user.name, t->u.target_size);
if (strcmp(t->u.user.name, STANDARD_TARGET) == 0) {
const unsigned char *data = t->data;
int pos = *(const int *)data;
if (pos < 0)
printf("verdict=%s\n",
pos == -NF_ACCEPT-1 ? "NF_ACCEPT"
: pos == -NF_DROP-1 ? "NF_DROP"
: pos == -NF_QUEUE-1 ? "NF_QUEUE"
: pos == RETURN ? "RETURN"
: "UNKNOWN");
else
printf("verdict=%u\n", pos);
} else if (strcmp(t->u.user.name, XT_ERROR_TARGET) == 0)
printf("error=`%s'\n", t->data);
printf("\n");
return 0;
}
static unsigned char *
is_same(const STRUCT_ENTRY *a, const STRUCT_ENTRY *b, unsigned char *matchmask)
{
unsigned int i;
unsigned char *mptr;
/* Always compare head structures: ignore mask here. */
if (a->ip.src.s_addr != b->ip.src.s_addr
|| a->ip.dst.s_addr != b->ip.dst.s_addr
|| a->ip.smsk.s_addr != b->ip.smsk.s_addr
|| a->ip.dmsk.s_addr != b->ip.dmsk.s_addr
|| a->ip.proto != b->ip.proto
|| a->ip.flags != b->ip.flags
|| a->ip.invflags != b->ip.invflags)
return NULL;
for (i = 0; i < IFNAMSIZ; i++) {
if (a->ip.iniface_mask[i] != b->ip.iniface_mask[i])
return NULL;
if ((a->ip.iniface[i] & a->ip.iniface_mask[i])
!= (b->ip.iniface[i] & b->ip.iniface_mask[i]))
return NULL;
if (a->ip.outiface_mask[i] != b->ip.outiface_mask[i])
return NULL;
if ((a->ip.outiface[i] & a->ip.outiface_mask[i])
!= (b->ip.outiface[i] & b->ip.outiface_mask[i]))
return NULL;
}
if (a->target_offset != b->target_offset
|| a->next_offset != b->next_offset)
return NULL;
mptr = matchmask + sizeof(STRUCT_ENTRY);
if (IPT_MATCH_ITERATE(a, match_different, a->elems, b->elems, &mptr))
return NULL;
mptr += XT_ALIGN(sizeof(struct xt_entry_target));
return mptr;
}
#if 0
/***************************** DEBUGGING ********************************/
static inline int
unconditional(const struct ipt_ip *ip)
{
unsigned int i;
for (i = 0; i < sizeof(*ip)/sizeof(uint32_t); i++)
if (((uint32_t *)ip)[i])
return 0;
return 1;
}
static inline int
check_match(const STRUCT_ENTRY_MATCH *m, unsigned int *off)
{
assert(m->u.match_size >= sizeof(STRUCT_ENTRY_MATCH));
assert(ALIGN(m->u.match_size) == m->u.match_size);
(*off) += m->u.match_size;
return 0;
}
static inline int
check_entry(const STRUCT_ENTRY *e, unsigned int *i, unsigned int *off,
unsigned int user_offset, int *was_return,
struct xtc_handle *h)
{
unsigned int toff;
STRUCT_STANDARD_TARGET *t;
assert(e->target_offset >= sizeof(STRUCT_ENTRY));
assert(e->next_offset >= e->target_offset
+ sizeof(STRUCT_ENTRY_TARGET));
toff = sizeof(STRUCT_ENTRY);
IPT_MATCH_ITERATE(e, check_match, &toff);
assert(toff == e->target_offset);
t = (STRUCT_STANDARD_TARGET *)
GET_TARGET((STRUCT_ENTRY *)e);
/* next_offset will have to be multiple of entry alignment. */
assert(e->next_offset == ALIGN(e->next_offset));
assert(e->target_offset == ALIGN(e->target_offset));
assert(t->target.u.target_size == ALIGN(t->target.u.target_size));
assert(!TC_IS_CHAIN(t->target.u.user.name, h));
if (strcmp(t->target.u.user.name, STANDARD_TARGET) == 0) {
assert(t->target.u.target_size
== ALIGN(sizeof(STRUCT_STANDARD_TARGET)));
assert(t->verdict == -NF_DROP-1
|| t->verdict == -NF_ACCEPT-1
|| t->verdict == RETURN
|| t->verdict < (int)h->entries->size);
if (t->verdict >= 0) {
STRUCT_ENTRY *te = get_entry(h, t->verdict);
int idx;
idx = iptcb_entry2index(h, te);
assert(strcmp(GET_TARGET(te)->u.user.name,
XT_ERROR_TARGET)
!= 0);
assert(te != e);
/* Prior node must be error node, or this node. */
assert(t->verdict == iptcb_entry2offset(h, e)+e->next_offset
|| strcmp(GET_TARGET(index2entry(h, idx-1))
->u.user.name, XT_ERROR_TARGET)
== 0);
}
if (t->verdict == RETURN
&& unconditional(&e->ip)
&& e->target_offset == sizeof(*e))
*was_return = 1;
else
*was_return = 0;
} else if (strcmp(t->target.u.user.name, XT_ERROR_TARGET) == 0) {
assert(t->target.u.target_size
== ALIGN(sizeof(struct ipt_error_target)));
/* If this is in user area, previous must have been return */
if (*off > user_offset)
assert(*was_return);
*was_return = 0;
}
else *was_return = 0;
if (*off == user_offset)
assert(strcmp(t->target.u.user.name, XT_ERROR_TARGET) == 0);
(*off) += e->next_offset;
(*i)++;
return 0;
}
#ifdef IPTC_DEBUG
/* Do every conceivable sanity check on the handle */
static void
do_check(struct xtc_handle *h, unsigned int line)
{
unsigned int i, n;
unsigned int user_offset; /* Offset of first user chain */
int was_return;
assert(h->changed == 0 || h->changed == 1);
if (strcmp(h->info.name, "filter") == 0) {
assert(h->info.valid_hooks
== (1 << NF_IP_LOCAL_IN
| 1 << NF_IP_FORWARD
| 1 << NF_IP_LOCAL_OUT));
/* Hooks should be first three */
assert(h->info.hook_entry[NF_IP_LOCAL_IN] == 0);
n = get_chain_end(h, 0);
n += get_entry(h, n)->next_offset;
assert(h->info.hook_entry[NF_IP_FORWARD] == n);
n = get_chain_end(h, n);
n += get_entry(h, n)->next_offset;
assert(h->info.hook_entry[NF_IP_LOCAL_OUT] == n);
user_offset = h->info.hook_entry[NF_IP_LOCAL_OUT];
} else if (strcmp(h->info.name, "nat") == 0) {
assert((h->info.valid_hooks
== (1 << NF_IP_PRE_ROUTING
| 1 << NF_IP_POST_ROUTING
| 1 << NF_IP_LOCAL_OUT)) ||
(h->info.valid_hooks
== (1 << NF_IP_PRE_ROUTING
| 1 << NF_IP_LOCAL_IN
| 1 << NF_IP_POST_ROUTING
| 1 << NF_IP_LOCAL_OUT)));
assert(h->info.hook_entry[NF_IP_PRE_ROUTING] == 0);
n = get_chain_end(h, 0);
n += get_entry(h, n)->next_offset;
assert(h->info.hook_entry[NF_IP_POST_ROUTING] == n);
n = get_chain_end(h, n);
n += get_entry(h, n)->next_offset;
assert(h->info.hook_entry[NF_IP_LOCAL_OUT] == n);
user_offset = h->info.hook_entry[NF_IP_LOCAL_OUT];
if (h->info.valid_hooks & (1 << NF_IP_LOCAL_IN)) {
n = get_chain_end(h, n);
n += get_entry(h, n)->next_offset;
assert(h->info.hook_entry[NF_IP_LOCAL_IN] == n);
user_offset = h->info.hook_entry[NF_IP_LOCAL_IN];
}
} else if (strcmp(h->info.name, "mangle") == 0) {
/* This code is getting ugly because linux < 2.4.18-pre6 had
* two mangle hooks, linux >= 2.4.18-pre6 has five mangle hooks
* */
assert((h->info.valid_hooks
== (1 << NF_IP_PRE_ROUTING
| 1 << NF_IP_LOCAL_OUT)) ||
(h->info.valid_hooks
== (1 << NF_IP_PRE_ROUTING
| 1 << NF_IP_LOCAL_IN
| 1 << NF_IP_FORWARD
| 1 << NF_IP_LOCAL_OUT
| 1 << NF_IP_POST_ROUTING)));
/* Hooks should be first five */
assert(h->info.hook_entry[NF_IP_PRE_ROUTING] == 0);
n = get_chain_end(h, 0);
if (h->info.valid_hooks & (1 << NF_IP_LOCAL_IN)) {
n += get_entry(h, n)->next_offset;
assert(h->info.hook_entry[NF_IP_LOCAL_IN] == n);
n = get_chain_end(h, n);
}
if (h->info.valid_hooks & (1 << NF_IP_FORWARD)) {
n += get_entry(h, n)->next_offset;
assert(h->info.hook_entry[NF_IP_FORWARD] == n);
n = get_chain_end(h, n);
}
n += get_entry(h, n)->next_offset;
assert(h->info.hook_entry[NF_IP_LOCAL_OUT] == n);
user_offset = h->info.hook_entry[NF_IP_LOCAL_OUT];
if (h->info.valid_hooks & (1 << NF_IP_POST_ROUTING)) {
n = get_chain_end(h, n);
n += get_entry(h, n)->next_offset;
assert(h->info.hook_entry[NF_IP_POST_ROUTING] == n);
user_offset = h->info.hook_entry[NF_IP_POST_ROUTING];
}
} else if (strcmp(h->info.name, "raw") == 0) {
assert(h->info.valid_hooks
== (1 << NF_IP_PRE_ROUTING
| 1 << NF_IP_LOCAL_OUT));
/* Hooks should be first three */
assert(h->info.hook_entry[NF_IP_PRE_ROUTING] == 0);
n = get_chain_end(h, n);
n += get_entry(h, n)->next_offset;
assert(h->info.hook_entry[NF_IP_LOCAL_OUT] == n);
user_offset = h->info.hook_entry[NF_IP_LOCAL_OUT];
} else {
fprintf(stderr, "Unknown table `%s'\n", h->info.name);
abort();
}
/* User chain == end of last builtin + policy entry */
user_offset = get_chain_end(h, user_offset);
user_offset += get_entry(h, user_offset)->next_offset;
/* Overflows should be end of entry chains, and unconditional
policy nodes. */
for (i = 0; i < NUMHOOKS; i++) {
STRUCT_ENTRY *e;
STRUCT_STANDARD_TARGET *t;
if (!(h->info.valid_hooks & (1 << i)))
continue;
assert(h->info.underflow[i]
== get_chain_end(h, h->info.hook_entry[i]));
e = get_entry(h, get_chain_end(h, h->info.hook_entry[i]));
assert(unconditional(&e->ip));
assert(e->target_offset == sizeof(*e));
t = (STRUCT_STANDARD_TARGET *)GET_TARGET(e);
assert(t->target.u.target_size == ALIGN(sizeof(*t)));
assert(e->next_offset == sizeof(*e) + ALIGN(sizeof(*t)));
assert(strcmp(t->target.u.user.name, STANDARD_TARGET)==0);
assert(t->verdict == -NF_DROP-1 || t->verdict == -NF_ACCEPT-1);
/* Hooks and underflows must be valid entries */
entry2index(h, get_entry(h, h->info.hook_entry[i]));
entry2index(h, get_entry(h, h->info.underflow[i]));
}
assert(h->info.size
>= h->info.num_entries * (sizeof(STRUCT_ENTRY)
+sizeof(STRUCT_STANDARD_TARGET)));
assert(h->entries.size
>= (h->new_number
* (sizeof(STRUCT_ENTRY)
+ sizeof(STRUCT_STANDARD_TARGET))));
assert(strcmp(h->info.name, h->entries.name) == 0);
i = 0; n = 0;
was_return = 0;
/* Check all the entries. */
ENTRY_ITERATE(h->entries.entrytable, h->entries.size,
check_entry, &i, &n, user_offset, &was_return, h);
assert(i == h->new_number);
assert(n == h->entries.size);
/* Final entry must be error node */
assert(strcmp(GET_TARGET(index2entry(h, h->new_number-1))
->u.user.name,
ERROR_TARGET) == 0);
}
#endif /*IPTC_DEBUG*/
#endif
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