Loading...
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 | /* Connection state tracking for netfilter. This is separated from,
but required by, the NAT layer; it can also be used by an iptables
extension. */
/* (c) 1999 Paul `Rusty' Russell. Licenced under the GNU General
Public Licence. */
#ifdef MODULE
#define __NO_VERSION__
#endif
#include <linux/version.h>
#include <linux/config.h>
#include <linux/types.h>
#include <linux/ip.h>
#include <linux/netfilter.h>
#include <linux/netfilter_ipv4.h>
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/proc_fs.h>
#include <linux/vmalloc.h>
#include <linux/brlock.h>
#include <net/checksum.h>
#include <linux/stddef.h>
#include <linux/sysctl.h>
#include <linux/slab.h>
/* This rwlock protects the main hash table, protocol/helper/expected
registrations, conntrack timers*/
#define ASSERT_READ_LOCK(x) MUST_BE_READ_LOCKED(&ip_conntrack_lock)
#define ASSERT_WRITE_LOCK(x) MUST_BE_WRITE_LOCKED(&ip_conntrack_lock)
#include <linux/netfilter_ipv4/ip_conntrack.h>
#include <linux/netfilter_ipv4/ip_conntrack_protocol.h>
#include <linux/netfilter_ipv4/ip_conntrack_helper.h>
#include <linux/netfilter_ipv4/ip_conntrack_core.h>
#include <linux/netfilter_ipv4/listhelp.h>
#if 0
#define DEBUGP printk
#else
#define DEBUGP(format, args...)
#endif
DECLARE_RWLOCK(ip_conntrack_lock);
void (*ip_conntrack_destroyed)(struct ip_conntrack *conntrack) = NULL;
LIST_HEAD(expect_list);
LIST_HEAD(protocol_list);
static LIST_HEAD(helpers);
unsigned int ip_conntrack_htable_size = 0;
static int ip_conntrack_max = 0;
static atomic_t ip_conntrack_count = ATOMIC_INIT(0);
struct list_head *ip_conntrack_hash;
static kmem_cache_t *ip_conntrack_cachep;
extern struct ip_conntrack_protocol ip_conntrack_generic_protocol;
static inline int proto_cmpfn(const struct ip_conntrack_protocol *curr,
u_int8_t protocol)
{
return protocol == curr->proto;
}
struct ip_conntrack_protocol *__find_proto(u_int8_t protocol)
{
struct ip_conntrack_protocol *p;
MUST_BE_READ_LOCKED(&ip_conntrack_lock);
p = LIST_FIND(&protocol_list, proto_cmpfn,
struct ip_conntrack_protocol *, protocol);
if (!p)
p = &ip_conntrack_generic_protocol;
return p;
}
struct ip_conntrack_protocol *find_proto(u_int8_t protocol)
{
struct ip_conntrack_protocol *p;
READ_LOCK(&ip_conntrack_lock);
p = __find_proto(protocol);
READ_UNLOCK(&ip_conntrack_lock);
return p;
}
static inline void ip_conntrack_put(struct ip_conntrack *ct)
{
IP_NF_ASSERT(ct);
IP_NF_ASSERT(ct->infos[0].master);
/* nf_conntrack_put wants to go via an info struct, so feed it
one at random. */
nf_conntrack_put(&ct->infos[0]);
}
static inline u_int32_t
hash_conntrack(const struct ip_conntrack_tuple *tuple)
{
#if 0
dump_tuple(tuple);
#endif
/* ntohl because more differences in low bits. */
/* To ensure that halves of the same connection don't hash
clash, we add the source per-proto again. */
return (ntohl(tuple->src.ip + tuple->dst.ip
+ tuple->src.u.all + tuple->dst.u.all
+ tuple->dst.protonum)
+ ntohs(tuple->src.u.all))
% ip_conntrack_htable_size;
}
inline int
get_tuple(const struct iphdr *iph, size_t len,
struct ip_conntrack_tuple *tuple,
struct ip_conntrack_protocol *protocol)
{
int ret;
/* Never happen */
if (iph->frag_off & htons(IP_OFFSET)) {
printk("ip_conntrack_core: Frag of proto %u.\n",
iph->protocol);
return 0;
}
/* Guarantee 8 protocol bytes: if more wanted, use len param */
else if (iph->ihl * 4 + 8 > len)
return 0;
tuple->src.ip = iph->saddr;
tuple->dst.ip = iph->daddr;
tuple->dst.protonum = iph->protocol;
ret = protocol->pkt_to_tuple((u_int32_t *)iph + iph->ihl,
len - 4*iph->ihl,
tuple);
return ret;
}
static int
invert_tuple(struct ip_conntrack_tuple *inverse,
const struct ip_conntrack_tuple *orig,
const struct ip_conntrack_protocol *protocol)
{
inverse->src.ip = orig->dst.ip;
inverse->dst.ip = orig->src.ip;
inverse->dst.protonum = orig->dst.protonum;
return protocol->invert_tuple(inverse, orig);
}
static void
clean_from_lists(struct ip_conntrack *ct)
{
MUST_BE_WRITE_LOCKED(&ip_conntrack_lock);
/* Remove from both hash lists */
LIST_DELETE(&ip_conntrack_hash
[hash_conntrack(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple)],
&ct->tuplehash[IP_CT_DIR_ORIGINAL]);
LIST_DELETE(&ip_conntrack_hash
[hash_conntrack(&ct->tuplehash[IP_CT_DIR_REPLY].tuple)],
&ct->tuplehash[IP_CT_DIR_REPLY]);
/* If our expected is in the list, take it out. */
if (ct->expected.expectant) {
IP_NF_ASSERT(list_inlist(&expect_list, &ct->expected));
IP_NF_ASSERT(ct->expected.expectant == ct);
LIST_DELETE(&expect_list, &ct->expected);
}
}
static void
destroy_conntrack(struct nf_conntrack *nfct)
{
struct ip_conntrack *ct = (struct ip_conntrack *)nfct;
/* Unconfirmed connections haven't been cleaned up by the
timer: hence they cannot be simply deleted here. */
if (!(ct->status & IPS_CONFIRMED)) {
WRITE_LOCK(&ip_conntrack_lock);
/* Race check: they can't get a reference if noone has
one and we have the write lock. */
if (atomic_read(&ct->ct_general.use) == 0) {
clean_from_lists(ct);
WRITE_UNLOCK(&ip_conntrack_lock);
} else {
/* Either a last-minute confirmation (ie. ct
now has timer attached), or a last-minute
new skb has reference (still unconfirmed). */
WRITE_UNLOCK(&ip_conntrack_lock);
return;
}
}
IP_NF_ASSERT(atomic_read(&nfct->use) == 0);
IP_NF_ASSERT(!timer_pending(&ct->timeout));
if (ct->master.master)
nf_conntrack_put(&ct->master);
if (ip_conntrack_destroyed)
ip_conntrack_destroyed(ct);
kmem_cache_free(ip_conntrack_cachep, ct);
atomic_dec(&ip_conntrack_count);
}
static void death_by_timeout(unsigned long ul_conntrack)
{
struct ip_conntrack *ct = (void *)ul_conntrack;
WRITE_LOCK(&ip_conntrack_lock);
IP_NF_ASSERT(ct->status & IPS_CONFIRMED);
clean_from_lists(ct);
WRITE_UNLOCK(&ip_conntrack_lock);
ip_conntrack_put(ct);
}
static inline int
conntrack_tuple_cmp(const struct ip_conntrack_tuple_hash *i,
const struct ip_conntrack_tuple *tuple,
const struct ip_conntrack *ignored_conntrack)
{
MUST_BE_READ_LOCKED(&ip_conntrack_lock);
return i->ctrack != ignored_conntrack
&& ip_ct_tuple_equal(tuple, &i->tuple);
}
static struct ip_conntrack_tuple_hash *
__ip_conntrack_find(const struct ip_conntrack_tuple *tuple,
const struct ip_conntrack *ignored_conntrack)
{
struct ip_conntrack_tuple_hash *h;
MUST_BE_READ_LOCKED(&ip_conntrack_lock);
h = LIST_FIND(&ip_conntrack_hash[hash_conntrack(tuple)],
conntrack_tuple_cmp,
struct ip_conntrack_tuple_hash *,
tuple, ignored_conntrack);
return h;
}
/* Find a connection corresponding to a tuple. */
struct ip_conntrack_tuple_hash *
ip_conntrack_find_get(const struct ip_conntrack_tuple *tuple,
const struct ip_conntrack *ignored_conntrack)
{
struct ip_conntrack_tuple_hash *h;
READ_LOCK(&ip_conntrack_lock);
h = __ip_conntrack_find(tuple, ignored_conntrack);
if (h)
atomic_inc(&h->ctrack->ct_general.use);
READ_UNLOCK(&ip_conntrack_lock);
return h;
}
/* Confirm a connection */
void
ip_conntrack_confirm(struct ip_conntrack *ct)
{
DEBUGP("Confirming conntrack %p\n", ct);
WRITE_LOCK(&ip_conntrack_lock);
/* Race check */
if (!(ct->status & IPS_CONFIRMED)) {
IP_NF_ASSERT(!timer_pending(&ct->timeout));
set_bit(IPS_CONFIRMED_BIT, &ct->status);
/* Timer relative to confirmation time, not original
setting time, otherwise we'd get timer wrap in
wierd delay cases. */
ct->timeout.expires += jiffies;
add_timer(&ct->timeout);
atomic_inc(&ct->ct_general.use);
}
WRITE_UNLOCK(&ip_conntrack_lock);
}
/* Returns true if a connection correspondings to the tuple (required
for NAT). */
int
ip_conntrack_tuple_taken(const struct ip_conntrack_tuple *tuple,
const struct ip_conntrack *ignored_conntrack)
{
struct ip_conntrack_tuple_hash *h;
READ_LOCK(&ip_conntrack_lock);
h = __ip_conntrack_find(tuple, ignored_conntrack);
READ_UNLOCK(&ip_conntrack_lock);
return h != NULL;
}
/* Returns conntrack if it dealt with ICMP, and filled in skb fields */
struct ip_conntrack *
icmp_error_track(struct sk_buff *skb,
enum ip_conntrack_info *ctinfo,
unsigned int hooknum)
{
const struct iphdr *iph;
struct icmphdr *hdr;
struct ip_conntrack_tuple innertuple, origtuple;
struct iphdr *inner;
size_t datalen;
struct ip_conntrack_protocol *innerproto;
struct ip_conntrack_tuple_hash *h;
IP_NF_ASSERT(iph->protocol == IPPROTO_ICMP);
IP_NF_ASSERT(skb->nfct == NULL);
iph = skb->nh.iph;
hdr = (struct icmphdr *)((u_int32_t *)iph + iph->ihl);
inner = (struct iphdr *)(hdr + 1);
datalen = skb->len - iph->ihl*4 - sizeof(*hdr);
if (skb->len < iph->ihl * 4 + sizeof(struct icmphdr)) {
DEBUGP("icmp_error_track: too short\n");
return NULL;
}
if (hdr->type != ICMP_DEST_UNREACH
&& hdr->type != ICMP_SOURCE_QUENCH
&& hdr->type != ICMP_TIME_EXCEEDED
&& hdr->type != ICMP_PARAMETERPROB
&& hdr->type != ICMP_REDIRECT)
return NULL;
/* Ignore ICMP's containing fragments (shouldn't happen) */
if (inner->frag_off & htons(IP_OFFSET)) {
DEBUGP("icmp_error_track: fragment of proto %u\n",
inner->protocol);
return NULL;
}
/* Ignore it if the checksum's bogus. */
if (ip_compute_csum((unsigned char *)hdr, sizeof(*hdr) + datalen)) {
DEBUGP("icmp_error_track: bad csum\n");
return NULL;
}
innerproto = find_proto(inner->protocol);
/* Are they talking about one of our connections? */
if (inner->ihl * 4 + 8 > datalen
|| !get_tuple(inner, datalen, &origtuple, innerproto)) {
DEBUGP("icmp_error: ! get_tuple p=%u (%u*4+%u dlen=%u)\n",
inner->protocol, inner->ihl, 8,
datalen);
return NULL;
}
/* Ordinarily, we'd expect the inverted tupleproto, but it's
been preserved inside the ICMP. */
if (!invert_tuple(&innertuple, &origtuple, innerproto)) {
DEBUGP("icmp_error_track: Can't invert tuple\n");
return NULL;
}
*ctinfo = IP_CT_RELATED;
h = ip_conntrack_find_get(&innertuple, NULL);
if (!h) {
/* Locally generated ICMPs will match inverted if they
haven't been SNAT'ed yet */
/* FIXME: NAT code has to handle half-done double NAT --RR */
if (hooknum == NF_IP_LOCAL_OUT)
h = ip_conntrack_find_get(&origtuple, NULL);
if (!h) {
DEBUGP("icmp_error_track: no match\n");
return NULL;
}
/* Reverse direction from that found */
if (DIRECTION(h) != IP_CT_DIR_REPLY)
*ctinfo += IP_CT_IS_REPLY;
} else {
if (DIRECTION(h) == IP_CT_DIR_REPLY)
*ctinfo += IP_CT_IS_REPLY;
}
/* REJECT target does this commonly, so allow locally
generated ICMP errors --RR */
if (!(h->ctrack->status & IPS_CONFIRMED)
&& hooknum != NF_IP_LOCAL_OUT) {
DEBUGP("icmp_error_track: unconfirmed\n");
ip_conntrack_put(h->ctrack);
return NULL;
}
/* Update skb to refer to this connection */
skb->nfct = &h->ctrack->infos[*ctinfo];
return h->ctrack;
}
/* There's a small race here where we may free a just-replied to
connection. Too bad: we're in trouble anyway. */
static inline int unreplied(const struct ip_conntrack_tuple_hash *i)
{
/* Unconfirmed connections either really fresh or transitory
anyway */
if (!(i->ctrack->status & IPS_ASSURED)
&& (i->ctrack->status & IPS_CONFIRMED))
return 1;
return 0;
}
static int early_drop(struct list_head *chain)
{
/* Traverse backwards: gives us oldest, which is roughly LRU */
struct ip_conntrack_tuple_hash *h;
int dropped = 0;
READ_LOCK(&ip_conntrack_lock);
h = LIST_FIND(chain, unreplied, struct ip_conntrack_tuple_hash *);
if (h)
atomic_inc(&h->ctrack->ct_general.use);
READ_UNLOCK(&ip_conntrack_lock);
if (!h)
return dropped;
if (del_timer(&h->ctrack->timeout)) {
death_by_timeout((unsigned long)h->ctrack);
dropped = 1;
}
ip_conntrack_put(h->ctrack);
return dropped;
}
static inline int helper_cmp(const struct ip_conntrack_helper *i,
const struct ip_conntrack_tuple *rtuple)
{
return ip_ct_tuple_mask_cmp(rtuple, &i->tuple, &i->mask);
}
/* Compare parts depending on mask. */
static inline int expect_cmp(const struct ip_conntrack_expect *i,
const struct ip_conntrack_tuple *tuple)
{
return ip_ct_tuple_mask_cmp(tuple, &i->tuple, &i->mask);
}
/* Allocate a new conntrack; we set everything up, then grab write
lock and see if we lost a race. If we lost it we return 0,
indicating the controlling code should look again. */
static int
init_conntrack(const struct ip_conntrack_tuple *tuple,
struct ip_conntrack_protocol *protocol,
struct sk_buff *skb)
{
struct ip_conntrack *conntrack;
struct ip_conntrack_tuple repl_tuple;
size_t hash, repl_hash;
struct ip_conntrack_expect *expected;
enum ip_conntrack_info ctinfo;
unsigned long extra_jiffies;
int i;
static unsigned int drop_next = 0;
hash = hash_conntrack(tuple);
if (ip_conntrack_max &&
atomic_read(&ip_conntrack_count) >= ip_conntrack_max) {
if (net_ratelimit())
printk(KERN_WARNING "ip_conntrack: maximum limit of"
" %d entries exceeded\n", ip_conntrack_max);
/* Try dropping from random chain, or else from the
chain about to put into (in case they're trying to
bomb one hash chain). */
if (drop_next >= ip_conntrack_htable_size)
drop_next = 0;
if (!early_drop(&ip_conntrack_hash[drop_next++])
&& !early_drop(&ip_conntrack_hash[hash]))
return 1;
}
if (!invert_tuple(&repl_tuple, tuple, protocol)) {
DEBUGP("Can't invert tuple.\n");
return 1;
}
repl_hash = hash_conntrack(&repl_tuple);
conntrack = kmem_cache_alloc(ip_conntrack_cachep, GFP_ATOMIC);
if (!conntrack) {
DEBUGP("Can't allocate conntrack.\n");
return 1;
}
memset(conntrack, 0, sizeof(struct ip_conntrack));
atomic_set(&conntrack->ct_general.use, 1);
conntrack->ct_general.destroy = destroy_conntrack;
conntrack->tuplehash[IP_CT_DIR_ORIGINAL].tuple = *tuple;
conntrack->tuplehash[IP_CT_DIR_ORIGINAL].ctrack = conntrack;
conntrack->tuplehash[IP_CT_DIR_REPLY].tuple = repl_tuple;
conntrack->tuplehash[IP_CT_DIR_REPLY].ctrack = conntrack;
for (i=0; i < IP_CT_NUMBER; i++)
conntrack->infos[i].master = &conntrack->ct_general;
extra_jiffies = protocol->new(conntrack, skb->nh.iph, skb->len);
if (!extra_jiffies) {
kmem_cache_free(ip_conntrack_cachep, conntrack);
return 1;
}
/* Don't set timer yet: wait for confirmation */
init_timer(&conntrack->timeout);
conntrack->timeout.data = (unsigned long)conntrack;
conntrack->timeout.function = death_by_timeout;
conntrack->timeout.expires = extra_jiffies;
/* Sew in at head of hash list. */
WRITE_LOCK(&ip_conntrack_lock);
/* Check noone else beat us in the race... */
if (__ip_conntrack_find(tuple, NULL)) {
WRITE_UNLOCK(&ip_conntrack_lock);
kmem_cache_free(ip_conntrack_cachep, conntrack);
return 0;
}
conntrack->helper = LIST_FIND(&helpers, helper_cmp,
struct ip_conntrack_helper *,
&repl_tuple);
/* Need finding and deleting of expected ONLY if we win race */
expected = LIST_FIND(&expect_list, expect_cmp,
struct ip_conntrack_expect *, tuple);
if (expected) {
/* Welcome, Mr. Bond. We've been expecting you... */
conntrack->status = IPS_EXPECTED;
conntrack->master.master = &expected->expectant->ct_general;
IP_NF_ASSERT(conntrack->master.master);
LIST_DELETE(&expect_list, expected);
expected->expectant = NULL;
nf_conntrack_get(&conntrack->master);
ctinfo = IP_CT_RELATED;
} else {
ctinfo = IP_CT_NEW;
}
list_prepend(&ip_conntrack_hash[hash],
&conntrack->tuplehash[IP_CT_DIR_ORIGINAL]);
list_prepend(&ip_conntrack_hash[repl_hash],
&conntrack->tuplehash[IP_CT_DIR_REPLY]);
atomic_inc(&ip_conntrack_count);
WRITE_UNLOCK(&ip_conntrack_lock);
/* Update skb to refer to this connection */
skb->nfct = &conntrack->infos[ctinfo];
if (expected && expected->expectfn)
expected->expectfn(conntrack);
return 1;
}
/* On success, returns conntrack ptr, sets skb->nfct and ctinfo */
static inline struct ip_conntrack *
resolve_normal_ct(struct sk_buff *skb,
struct ip_conntrack_protocol *proto,
int *set_reply,
unsigned int hooknum,
enum ip_conntrack_info *ctinfo)
{
struct ip_conntrack_tuple tuple;
struct ip_conntrack_tuple_hash *h;
IP_NF_ASSERT((skb->nh.iph->frag_off & htons(IP_OFFSET)) == 0);
if (!get_tuple(skb->nh.iph, skb->len, &tuple, proto))
return NULL;
/* Loop around search/insert race */
do {
/* look for tuple match */
h = ip_conntrack_find_get(&tuple, NULL);
if (!h && init_conntrack(&tuple, proto, skb))
return NULL;
} while (!h);
/* It exists; we have (non-exclusive) reference. */
if (DIRECTION(h) == IP_CT_DIR_REPLY) {
/* Reply on unconfirmed connection => unclassifiable */
if (!(h->ctrack->status & IPS_CONFIRMED)) {
/* Exception: local TCP RSTs (generated by
REJECT target). */
if (hooknum == NF_IP_LOCAL_OUT
&& h->tuple.dst.protonum == IPPROTO_TCP) {
const struct tcphdr *tcph
= (const struct tcphdr *)
((u_int32_t *)skb->nh.iph
+ skb->nh.iph->ihl);
if (tcph->rst) {
*ctinfo = IP_CT_ESTABLISHED
+ IP_CT_IS_REPLY;
*set_reply = 0;
goto set_skb;
}
}
DEBUGP("Reply on unconfirmed connection\n");
ip_conntrack_put(h->ctrack);
return NULL;
}
*ctinfo = IP_CT_ESTABLISHED + IP_CT_IS_REPLY;
/* Please set reply bit if this packet OK */
*set_reply = 1;
} else {
/* Once we've had two way comms, always ESTABLISHED. */
if (h->ctrack->status & IPS_SEEN_REPLY) {
DEBUGP("ip_conntrack_in: normal packet for %p\n",
h->ctrack);
*ctinfo = IP_CT_ESTABLISHED;
} else if (h->ctrack->status & IPS_EXPECTED) {
DEBUGP("ip_conntrack_in: related packet for %p\n",
h->ctrack);
*ctinfo = IP_CT_RELATED;
} else {
DEBUGP("ip_conntrack_in: new packet for %p\n",
h->ctrack);
*ctinfo = IP_CT_NEW;
}
*set_reply = 0;
}
set_skb:
skb->nfct = &h->ctrack->infos[*ctinfo];
return h->ctrack;
}
/* Return conntrack and conntrack_info a given skb */
inline struct ip_conntrack *
ip_conntrack_get(struct sk_buff *skb, enum ip_conntrack_info *ctinfo)
{
if (skb->nfct) {
struct ip_conntrack *ct
= (struct ip_conntrack *)skb->nfct->master;
/* ctinfo is the index of the nfct inside the conntrack */
*ctinfo = skb->nfct - ct->infos;
IP_NF_ASSERT(*ctinfo >= 0 && *ctinfo < IP_CT_NUMBER);
return ct;
}
return NULL;
}
/* Netfilter hook itself. */
unsigned int ip_conntrack_in(unsigned int hooknum,
struct sk_buff **pskb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
struct ip_conntrack *ct;
enum ip_conntrack_info ctinfo;
struct ip_conntrack_protocol *proto;
int set_reply;
int ret;
/* FIXME: Do this right please. --RR */
(*pskb)->nfcache |= NFC_UNKNOWN;
/* Doesn't cover locally-generated broadcast, so not worth it. */
#if 0
/* Ignore broadcast: no `connection'. */
if ((*pskb)->pkt_type == PACKET_BROADCAST) {
printk("Broadcast packet!\n");
return NF_ACCEPT;
} else if (((*pskb)->nh.iph->daddr & htonl(0x000000FF))
== htonl(0x000000FF)) {
printk("Should bcast: %u.%u.%u.%u->%u.%u.%u.%u (sk=%p, ptype=%u)\n",
IP_PARTS((*pskb)->nh.iph->saddr),
IP_PARTS((*pskb)->nh.iph->daddr),
(*pskb)->sk, (*pskb)->pkt_type);
}
#endif
/* Previously seen (loopback)? Ignore. Do this before
fragment check. */
if ((*pskb)->nfct)
return NF_ACCEPT;
/* Gather fragments. */
if ((*pskb)->nh.iph->frag_off & htons(IP_MF|IP_OFFSET)) {
*pskb = ip_ct_gather_frags(*pskb);
if (!*pskb)
return NF_STOLEN;
}
proto = find_proto((*pskb)->nh.iph->protocol);
/* It may be an icmp error... */
if ((*pskb)->nh.iph->protocol == IPPROTO_ICMP
&& icmp_error_track(*pskb, &ctinfo, hooknum))
return NF_ACCEPT;
if (!(ct = resolve_normal_ct(*pskb, proto,&set_reply,hooknum,&ctinfo)))
/* Not valid part of a connection */
return NF_ACCEPT;
IP_NF_ASSERT((*pskb)->nfct);
ret = proto->packet(ct, (*pskb)->nh.iph, (*pskb)->len, ctinfo);
if (ret == -1) {
/* Invalid */
nf_conntrack_put((*pskb)->nfct);
(*pskb)->nfct = NULL;
return NF_ACCEPT;
}
if (ret != NF_DROP && ct->helper) {
ret = ct->helper->help((*pskb)->nh.iph, (*pskb)->len,
ct, ctinfo);
if (ret == -1) {
/* Invalid */
nf_conntrack_put((*pskb)->nfct);
(*pskb)->nfct = NULL;
return NF_ACCEPT;
}
}
if (set_reply)
set_bit(IPS_SEEN_REPLY_BIT, &ct->status);
return ret;
}
int invert_tuplepr(struct ip_conntrack_tuple *inverse,
const struct ip_conntrack_tuple *orig)
{
return invert_tuple(inverse, orig, find_proto(orig->dst.protonum));
}
static void unexpect_related(struct ip_conntrack *related_to)
{
MUST_BE_WRITE_LOCKED(&ip_conntrack_lock);
list_del(&related_to->expected.list);
related_to->expected.expectant = NULL;
}
/* Would two expected things clash? */
static inline int expect_clash(const struct ip_conntrack_expect *i,
const struct ip_conntrack_expect *new)
{
/* Part covered by intersection of masks must be unequal,
otherwise they clash */
struct ip_conntrack_tuple intersect_mask
= { { i->mask.src.ip & new->mask.src.ip,
{ i->mask.src.u.all & new->mask.src.u.all } },
{ i->mask.dst.ip & new->mask.dst.ip,
{ i->mask.dst.u.all & new->mask.dst.u.all },
i->mask.dst.protonum & new->mask.dst.protonum } };
return ip_ct_tuple_mask_cmp(&i->tuple, &new->tuple, &intersect_mask);
}
/* Add a related connection. */
int ip_conntrack_expect_related(struct ip_conntrack *related_to,
const struct ip_conntrack_tuple *tuple,
const struct ip_conntrack_tuple *mask,
int (*expectfn)(struct ip_conntrack *))
{
WRITE_LOCK(&ip_conntrack_lock);
if (related_to->expected.expectant)
unexpect_related(related_to);
related_to->expected.tuple = *tuple;
related_to->expected.mask = *mask;
related_to->expected.expectfn = expectfn;
if (LIST_FIND(&expect_list, expect_clash,
struct ip_conntrack_expect *, &related_to->expected)) {
WRITE_UNLOCK(&ip_conntrack_lock);
return -EBUSY;
}
list_prepend(&expect_list, &related_to->expected);
related_to->expected.expectant = related_to;
WRITE_UNLOCK(&ip_conntrack_lock);
return 0;
}
void ip_conntrack_unexpect_related(struct ip_conntrack *related_to)
{
WRITE_LOCK(&ip_conntrack_lock);
unexpect_related(related_to);
WRITE_UNLOCK(&ip_conntrack_lock);
}
/* Alter reply tuple (maybe alter helper). If it's already taken,
return 0 and don't do alteration. */
int ip_conntrack_alter_reply(struct ip_conntrack *conntrack,
const struct ip_conntrack_tuple *newreply)
{
unsigned int newindex = hash_conntrack(newreply);
WRITE_LOCK(&ip_conntrack_lock);
if (__ip_conntrack_find(newreply, conntrack)) {
WRITE_UNLOCK(&ip_conntrack_lock);
return 0;
}
DEBUGP("Altering reply tuple of %p to ", conntrack);
DUMP_TUPLE(newreply);
LIST_DELETE(&ip_conntrack_hash
[hash_conntrack(&conntrack->tuplehash[IP_CT_DIR_REPLY]
.tuple)],
&conntrack->tuplehash[IP_CT_DIR_REPLY]);
conntrack->tuplehash[IP_CT_DIR_REPLY].tuple = *newreply;
list_prepend(&ip_conntrack_hash[newindex],
&conntrack->tuplehash[IP_CT_DIR_REPLY]);
conntrack->helper = LIST_FIND(&helpers, helper_cmp,
struct ip_conntrack_helper *,
newreply);
WRITE_UNLOCK(&ip_conntrack_lock);
return 1;
}
int ip_conntrack_helper_register(struct ip_conntrack_helper *me)
{
MOD_INC_USE_COUNT;
WRITE_LOCK(&ip_conntrack_lock);
list_prepend(&helpers, me);
WRITE_UNLOCK(&ip_conntrack_lock);
return 0;
}
static inline int unhelp(struct ip_conntrack_tuple_hash *i,
const struct ip_conntrack_helper *me)
{
if (i->ctrack->helper == me) {
i->ctrack->helper = NULL;
/* Get rid of any expected. */
if (i->ctrack->expected.expectant) {
IP_NF_ASSERT(i->ctrack->expected.expectant
== i->ctrack);
LIST_DELETE(&expect_list, &i->ctrack->expected);
i->ctrack->expected.expectant = NULL;
}
}
return 0;
}
void ip_conntrack_helper_unregister(struct ip_conntrack_helper *me)
{
unsigned int i;
/* Need write lock here, to delete helper. */
WRITE_LOCK(&ip_conntrack_lock);
LIST_DELETE(&helpers, me);
/* Get rid of expecteds, set helpers to NULL. */
for (i = 0; i < ip_conntrack_htable_size; i++)
LIST_FIND_W(&ip_conntrack_hash[i], unhelp,
struct ip_conntrack_tuple_hash *, me);
WRITE_UNLOCK(&ip_conntrack_lock);
/* Someone could be still looking at the helper in a bh. */
br_write_lock_bh(BR_NETPROTO_LOCK);
br_write_unlock_bh(BR_NETPROTO_LOCK);
MOD_DEC_USE_COUNT;
}
/* Refresh conntrack for this many jiffies. */
void ip_ct_refresh(struct ip_conntrack *ct, unsigned long extra_jiffies)
{
IP_NF_ASSERT(ct->timeout.data == (unsigned long)ct);
WRITE_LOCK(&ip_conntrack_lock);
/* Timer may not be active yet */
if (!(ct->status & IPS_CONFIRMED))
ct->timeout.expires = extra_jiffies;
else {
/* Need del_timer for race avoidance (may already be dying). */
if (del_timer(&ct->timeout)) {
ct->timeout.expires = jiffies + extra_jiffies;
add_timer(&ct->timeout);
}
}
WRITE_UNLOCK(&ip_conntrack_lock);
}
/* Returns new sk_buff, or NULL */
struct sk_buff *
ip_ct_gather_frags(struct sk_buff *skb)
{
struct sock *sk = skb->sk;
#ifdef CONFIG_NETFILTER_DEBUG
unsigned int olddebug = skb->nf_debug;
#endif
if (sk) sock_hold(sk);
local_bh_disable();
skb = ip_defrag(skb);
local_bh_enable();
if (!skb) {
if (sk) sock_put(sk);
return skb;
}
if (sk) {
skb_set_owner_w(skb, sk);
sock_put(sk);
}
ip_send_check(skb->nh.iph);
skb->nfcache |= NFC_ALTERED;
#ifdef CONFIG_NETFILTER_DEBUG
/* Packet path as if nothing had happened. */
skb->nf_debug = olddebug;
#endif
return skb;
}
static inline int
do_kill(const struct ip_conntrack_tuple_hash *i,
int (*kill)(const struct ip_conntrack *i, void *data),
void *data)
{
return kill(i->ctrack, data);
}
/* Bring out ya dead! */
static struct ip_conntrack_tuple_hash *
get_next_corpse(int (*kill)(const struct ip_conntrack *i, void *data),
void *data)
{
struct ip_conntrack_tuple_hash *h = NULL;
unsigned int i;
READ_LOCK(&ip_conntrack_lock);
for (i = 0; !h && i < ip_conntrack_htable_size; i++) {
h = LIST_FIND(&ip_conntrack_hash[i], do_kill,
struct ip_conntrack_tuple_hash *, kill, data);
}
if (h)
atomic_inc(&h->ctrack->ct_general.use);
READ_UNLOCK(&ip_conntrack_lock);
return h;
}
void
ip_ct_selective_cleanup(int (*kill)(const struct ip_conntrack *i, void *data),
void *data)
{
struct ip_conntrack_tuple_hash *h;
/* This is order n^2, by the way. */
while ((h = get_next_corpse(kill, data)) != NULL) {
/* Time to push up daises... */
if (del_timer(&h->ctrack->timeout))
death_by_timeout((unsigned long)h->ctrack);
else if (!(h->ctrack->status & IPS_CONFIRMED)) {
/* Unconfirmed connection. Clean from lists,
mark confirmed so it gets cleaned as soon
as skb freed. */
WRITE_LOCK(&ip_conntrack_lock);
/* Lock protects race against another setting
of confirmed bit. set_bit isolates this
bit from the others. */
if (!(h->ctrack->status & IPS_CONFIRMED)) {
clean_from_lists(h->ctrack);
set_bit(IPS_CONFIRMED_BIT, &h->ctrack->status);
}
WRITE_UNLOCK(&ip_conntrack_lock);
}
/* ... else the timer will get him soon. */
ip_conntrack_put(h->ctrack);
}
}
/* Fast function for those who don't want to parse /proc (and I don't
blame them). */
/* Reversing the socket's dst/src point of view gives us the reply
mapping. */
static int
getorigdst(struct sock *sk, int optval, void *user, int *len)
{
struct ip_conntrack_tuple_hash *h;
struct ip_conntrack_tuple tuple = { { sk->rcv_saddr, { sk->sport } },
{ sk->daddr, { sk->dport },
IPPROTO_TCP } };
/* We only do TCP at the moment: is there a better way? */
if (strcmp(sk->prot->name, "TCP") != 0) {
DEBUGP("SO_ORIGINAL_DST: Not a TCP socket\n");
return -ENOPROTOOPT;
}
if (*len != sizeof(struct sockaddr_in)) {
DEBUGP("SO_ORIGINAL_DST: len %u not %u\n",
*len, sizeof(struct sockaddr_in));
return -EINVAL;
}
h = ip_conntrack_find_get(&tuple, NULL);
if (h) {
struct sockaddr_in sin;
sin.sin_family = AF_INET;
sin.sin_port = h->ctrack->tuplehash[IP_CT_DIR_ORIGINAL]
.tuple.dst.u.tcp.port;
sin.sin_addr.s_addr = h->ctrack->tuplehash[IP_CT_DIR_ORIGINAL]
.tuple.dst.ip;
DEBUGP("SO_ORIGINAL_DST: %u.%u.%u.%u %u\n",
IP_PARTS(sin.sin_addr.s_addr), ntohs(sin.sin_port));
ip_conntrack_put(h->ctrack);
if (copy_to_user(user, &sin, sizeof(sin)) != 0)
return -EFAULT;
else
return 0;
}
DEBUGP("SO_ORIGINAL_DST: Can't find %u.%u.%u.%u/%u-%u.%u.%u.%u/%u.\n",
IP_PARTS(tuple.src.ip), ntohs(tuple.src.u.tcp.port),
IP_PARTS(tuple.dst.ip), ntohs(tuple.dst.u.tcp.port));
return -ENOENT;
}
static struct nf_sockopt_ops so_getorigdst
= { { NULL, NULL }, PF_INET,
0, 0, NULL, /* Setsockopts */
SO_ORIGINAL_DST, SO_ORIGINAL_DST+1, &getorigdst,
0, NULL };
#define NET_IP_CONNTRACK_MAX 2089
#define NET_IP_CONNTRACK_MAX_NAME "ip_conntrack_max"
#ifdef CONFIG_SYSCTL
static struct ctl_table_header *ip_conntrack_sysctl_header;
static ctl_table ip_conntrack_table[] = {
{ NET_IP_CONNTRACK_MAX, NET_IP_CONNTRACK_MAX_NAME, &ip_conntrack_max,
sizeof(ip_conntrack_max), 0644, NULL, proc_dointvec },
{ 0 }
};
static ctl_table ip_conntrack_dir_table[] = {
{NET_IPV4, "ipv4", NULL, 0, 0555, ip_conntrack_table, 0, 0, 0, 0, 0},
{ 0 }
};
static ctl_table ip_conntrack_root_table[] = {
{CTL_NET, "net", NULL, 0, 0555, ip_conntrack_dir_table, 0, 0, 0, 0, 0},
{ 0 }
};
#endif /*CONFIG_SYSCTL*/
static int kill_all(const struct ip_conntrack *i, void *data)
{
return 1;
}
/* Mishearing the voices in his head, our hero wonders how he's
supposed to kill the mall. */
void ip_conntrack_cleanup(void)
{
#ifdef CONFIG_SYSCTL
unregister_sysctl_table(ip_conntrack_sysctl_header);
#endif
i_see_dead_people:
ip_ct_selective_cleanup(kill_all, NULL);
if (atomic_read(&ip_conntrack_count) != 0) {
schedule();
goto i_see_dead_people;
}
kmem_cache_destroy(ip_conntrack_cachep);
vfree(ip_conntrack_hash);
nf_unregister_sockopt(&so_getorigdst);
}
int __init ip_conntrack_init(void)
{
unsigned int i;
int ret;
/* Idea from tcp.c: use 1/16384 of memory. On i386: 32MB
* machine has 256 buckets. 1GB machine has 8192 buckets. */
ip_conntrack_htable_size
= (((num_physpages << PAGE_SHIFT) / 16384)
/ sizeof(struct list_head));
ip_conntrack_max = 8 * ip_conntrack_htable_size;
printk("ip_conntrack (%u buckets, %d max)\n",
ip_conntrack_htable_size, ip_conntrack_max);
ret = nf_register_sockopt(&so_getorigdst);
if (ret != 0)
return ret;
ip_conntrack_hash = vmalloc(sizeof(struct list_head)
* ip_conntrack_htable_size);
if (!ip_conntrack_hash) {
nf_unregister_sockopt(&so_getorigdst);
return -ENOMEM;
}
ip_conntrack_cachep = kmem_cache_create("ip_conntrack",
sizeof(struct ip_conntrack), 0,
SLAB_HWCACHE_ALIGN, NULL, NULL);
if (!ip_conntrack_cachep) {
printk(KERN_ERR "Unable to create ip_conntrack slab cache\n");
vfree(ip_conntrack_hash);
nf_unregister_sockopt(&so_getorigdst);
return -ENOMEM;
}
/* Don't NEED lock here, but good form anyway. */
WRITE_LOCK(&ip_conntrack_lock);
/* Sew in builtin protocols. */
list_append(&protocol_list, &ip_conntrack_protocol_tcp);
list_append(&protocol_list, &ip_conntrack_protocol_udp);
list_append(&protocol_list, &ip_conntrack_protocol_icmp);
WRITE_UNLOCK(&ip_conntrack_lock);
for (i = 0; i < ip_conntrack_htable_size; i++)
INIT_LIST_HEAD(&ip_conntrack_hash[i]);
/* This is fucking braindead. There is NO WAY of doing this without
the CONFIG_SYSCTL unless you don't want to detect errors.
Grrr... --RR */
#ifdef CONFIG_SYSCTL
ip_conntrack_sysctl_header
= register_sysctl_table(ip_conntrack_root_table, 0);
if (ip_conntrack_sysctl_header == NULL) {
kmem_cache_destroy(ip_conntrack_cachep);
vfree(ip_conntrack_hash);
nf_unregister_sockopt(&so_getorigdst);
return -ENOMEM;
}
#endif /*CONFIG_SYSCTL*/
return ret;
}
|