diff options
Diffstat (limited to 'net/ipv4/netfilter/ip_conntrack_proto_tcp.c')
| -rw-r--r-- | net/ipv4/netfilter/ip_conntrack_proto_tcp.c | 1164 |
1 files changed, 0 insertions, 1164 deletions
diff --git a/net/ipv4/netfilter/ip_conntrack_proto_tcp.c b/net/ipv4/netfilter/ip_conntrack_proto_tcp.c deleted file mode 100644 index 0a72eab14620..000000000000 --- a/net/ipv4/netfilter/ip_conntrack_proto_tcp.c +++ /dev/null @@ -1,1164 +0,0 @@ -/* (C) 1999-2001 Paul `Rusty' Russell - * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org> - * - * This program is free software; you can redistribute it and/or modify - * it under the terms of the GNU General Public License version 2 as - * published by the Free Software Foundation. - * - * Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>: - * - Real stateful connection tracking - * - Modified state transitions table - * - Window scaling support added - * - SACK support added - * - * Willy Tarreau: - * - State table bugfixes - * - More robust state changes - * - Tuning timer parameters - * - * version 2.2 - */ - -#include <linux/types.h> -#include <linux/timer.h> -#include <linux/netfilter.h> -#include <linux/module.h> -#include <linux/in.h> -#include <linux/ip.h> -#include <linux/tcp.h> -#include <linux/spinlock.h> - -#include <net/tcp.h> - -#include <linux/netfilter_ipv4.h> -#include <linux/netfilter_ipv4/ip_conntrack.h> -#include <linux/netfilter_ipv4/ip_conntrack_protocol.h> - -#if 0 -#define DEBUGP printk -#define DEBUGP_VARS -#else -#define DEBUGP(format, args...) -#endif - -/* Protects conntrack->proto.tcp */ -static DEFINE_RWLOCK(tcp_lock); - -/* "Be conservative in what you do, - be liberal in what you accept from others." - If it's non-zero, we mark only out of window RST segments as INVALID. */ -int ip_ct_tcp_be_liberal __read_mostly = 0; - -/* If it is set to zero, we disable picking up already established - connections. */ -int ip_ct_tcp_loose __read_mostly = 1; - -/* Max number of the retransmitted packets without receiving an (acceptable) - ACK from the destination. If this number is reached, a shorter timer - will be started. */ -int ip_ct_tcp_max_retrans __read_mostly = 3; - - /* FIXME: Examine ipfilter's timeouts and conntrack transitions more - closely. They're more complex. --RR */ - -static const char *tcp_conntrack_names[] = { - "NONE", - "SYN_SENT", - "SYN_RECV", - "ESTABLISHED", - "FIN_WAIT", - "CLOSE_WAIT", - "LAST_ACK", - "TIME_WAIT", - "CLOSE", - "LISTEN" -}; - -#define SECS * HZ -#define MINS * 60 SECS -#define HOURS * 60 MINS -#define DAYS * 24 HOURS - -unsigned int ip_ct_tcp_timeout_syn_sent __read_mostly = 2 MINS; -unsigned int ip_ct_tcp_timeout_syn_recv __read_mostly = 60 SECS; -unsigned int ip_ct_tcp_timeout_established __read_mostly = 5 DAYS; -unsigned int ip_ct_tcp_timeout_fin_wait __read_mostly = 2 MINS; -unsigned int ip_ct_tcp_timeout_close_wait __read_mostly = 60 SECS; -unsigned int ip_ct_tcp_timeout_last_ack __read_mostly = 30 SECS; -unsigned int ip_ct_tcp_timeout_time_wait __read_mostly = 2 MINS; -unsigned int ip_ct_tcp_timeout_close __read_mostly = 10 SECS; - -/* RFC1122 says the R2 limit should be at least 100 seconds. - Linux uses 15 packets as limit, which corresponds - to ~13-30min depending on RTO. */ -unsigned int ip_ct_tcp_timeout_max_retrans __read_mostly = 5 MINS; - -static const unsigned int * tcp_timeouts[] -= { NULL, /* TCP_CONNTRACK_NONE */ - &ip_ct_tcp_timeout_syn_sent, /* TCP_CONNTRACK_SYN_SENT, */ - &ip_ct_tcp_timeout_syn_recv, /* TCP_CONNTRACK_SYN_RECV, */ - &ip_ct_tcp_timeout_established, /* TCP_CONNTRACK_ESTABLISHED, */ - &ip_ct_tcp_timeout_fin_wait, /* TCP_CONNTRACK_FIN_WAIT, */ - &ip_ct_tcp_timeout_close_wait, /* TCP_CONNTRACK_CLOSE_WAIT, */ - &ip_ct_tcp_timeout_last_ack, /* TCP_CONNTRACK_LAST_ACK, */ - &ip_ct_tcp_timeout_time_wait, /* TCP_CONNTRACK_TIME_WAIT, */ - &ip_ct_tcp_timeout_close, /* TCP_CONNTRACK_CLOSE, */ - NULL, /* TCP_CONNTRACK_LISTEN */ - }; - -#define sNO TCP_CONNTRACK_NONE -#define sSS TCP_CONNTRACK_SYN_SENT -#define sSR TCP_CONNTRACK_SYN_RECV -#define sES TCP_CONNTRACK_ESTABLISHED -#define sFW TCP_CONNTRACK_FIN_WAIT -#define sCW TCP_CONNTRACK_CLOSE_WAIT -#define sLA TCP_CONNTRACK_LAST_ACK -#define sTW TCP_CONNTRACK_TIME_WAIT -#define sCL TCP_CONNTRACK_CLOSE -#define sLI TCP_CONNTRACK_LISTEN -#define sIV TCP_CONNTRACK_MAX -#define sIG TCP_CONNTRACK_IGNORE - -/* What TCP flags are set from RST/SYN/FIN/ACK. */ -enum tcp_bit_set { - TCP_SYN_SET, - TCP_SYNACK_SET, - TCP_FIN_SET, - TCP_ACK_SET, - TCP_RST_SET, - TCP_NONE_SET, -}; - -/* - * The TCP state transition table needs a few words... - * - * We are the man in the middle. All the packets go through us - * but might get lost in transit to the destination. - * It is assumed that the destinations can't receive segments - * we haven't seen. - * - * The checked segment is in window, but our windows are *not* - * equivalent with the ones of the sender/receiver. We always - * try to guess the state of the current sender. - * - * The meaning of the states are: - * - * NONE: initial state - * SYN_SENT: SYN-only packet seen - * SYN_RECV: SYN-ACK packet seen - * ESTABLISHED: ACK packet seen - * FIN_WAIT: FIN packet seen - * CLOSE_WAIT: ACK seen (after FIN) - * LAST_ACK: FIN seen (after FIN) - * TIME_WAIT: last ACK seen - * CLOSE: closed connection - * - * LISTEN state is not used. - * - * Packets marked as IGNORED (sIG): - * if they may be either invalid or valid - * and the receiver may send back a connection - * closing RST or a SYN/ACK. - * - * Packets marked as INVALID (sIV): - * if they are invalid - * or we do not support the request (simultaneous open) - */ -static const enum tcp_conntrack tcp_conntracks[2][6][TCP_CONNTRACK_MAX] = { - { -/* ORIGINAL */ -/* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sLI */ -/*syn*/ { sSS, sSS, sIG, sIG, sIG, sIG, sIG, sSS, sSS, sIV }, -/* - * sNO -> sSS Initialize a new connection - * sSS -> sSS Retransmitted SYN - * sSR -> sIG Late retransmitted SYN? - * sES -> sIG Error: SYNs in window outside the SYN_SENT state - * are errors. Receiver will reply with RST - * and close the connection. - * Or we are not in sync and hold a dead connection. - * sFW -> sIG - * sCW -> sIG - * sLA -> sIG - * sTW -> sSS Reopened connection (RFC 1122). - * sCL -> sSS - */ -/* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sLI */ -/*synack*/ { sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV }, -/* - * A SYN/ACK from the client is always invalid: - * - either it tries to set up a simultaneous open, which is - * not supported; - * - or the firewall has just been inserted between the two hosts - * during the session set-up. The SYN will be retransmitted - * by the true client (or it'll time out). - */ -/* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sLI */ -/*fin*/ { sIV, sIV, sFW, sFW, sLA, sLA, sLA, sTW, sCL, sIV }, -/* - * sNO -> sIV Too late and no reason to do anything... - * sSS -> sIV Client migth not send FIN in this state: - * we enforce waiting for a SYN/ACK reply first. - * sSR -> sFW Close started. - * sES -> sFW - * sFW -> sLA FIN seen in both directions, waiting for - * the last ACK. - * Migth be a retransmitted FIN as well... - * sCW -> sLA - * sLA -> sLA Retransmitted FIN. Remain in the same state. - * sTW -> sTW - * sCL -> sCL - */ -/* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sLI */ -/*ack*/ { sES, sIV, sES, sES, sCW, sCW, sTW, sTW, sCL, sIV }, -/* - * sNO -> sES Assumed. - * sSS -> sIV ACK is invalid: we haven't seen a SYN/ACK yet. - * sSR -> sES Established state is reached. - * sES -> sES :-) - * sFW -> sCW Normal close request answered by ACK. - * sCW -> sCW - * sLA -> sTW Last ACK detected. - * sTW -> sTW Retransmitted last ACK. Remain in the same state. - * sCL -> sCL - */ -/* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sLI */ -/*rst*/ { sIV, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sIV }, -/*none*/ { sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV } - }, - { -/* REPLY */ -/* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sLI */ -/*syn*/ { sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV }, -/* - * sNO -> sIV Never reached. - * sSS -> sIV Simultaneous open, not supported - * sSR -> sIV Simultaneous open, not supported. - * sES -> sIV Server may not initiate a connection. - * sFW -> sIV - * sCW -> sIV - * sLA -> sIV - * sTW -> sIV Reopened connection, but server may not do it. - * sCL -> sIV - */ -/* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sLI */ -/*synack*/ { sIV, sSR, sSR, sIG, sIG, sIG, sIG, sIG, sIG, sIV }, -/* - * sSS -> sSR Standard open. - * sSR -> sSR Retransmitted SYN/ACK. - * sES -> sIG Late retransmitted SYN/ACK? - * sFW -> sIG Might be SYN/ACK answering ignored SYN - * sCW -> sIG - * sLA -> sIG - * sTW -> sIG - * sCL -> sIG - */ -/* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sLI */ -/*fin*/ { sIV, sIV, sFW, sFW, sLA, sLA, sLA, sTW, sCL, sIV }, -/* - * sSS -> sIV Server might not send FIN in this state. - * sSR -> sFW Close started. - * sES -> sFW - * sFW -> sLA FIN seen in both directions. - * sCW -> sLA - * sLA -> sLA Retransmitted FIN. - * sTW -> sTW - * sCL -> sCL - */ -/* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sLI */ -/*ack*/ { sIV, sIG, sSR, sES, sCW, sCW, sTW, sTW, sCL, sIV }, -/* - * sSS -> sIG Might be a half-open connection. - * sSR -> sSR Might answer late resent SYN. - * sES -> sES :-) - * sFW -> sCW Normal close request answered by ACK. - * sCW -> sCW - * sLA -> sTW Last ACK detected. - * sTW -> sTW Retransmitted last ACK. - * sCL -> sCL - */ -/* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sLI */ -/*rst*/ { sIV, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sIV }, -/*none*/ { sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV } - } -}; - -static int tcp_pkt_to_tuple(const struct sk_buff *skb, - unsigned int dataoff, - struct ip_conntrack_tuple *tuple) -{ - struct tcphdr _hdr, *hp; - - /* Actually only need first 8 bytes. */ - hp = skb_header_pointer(skb, dataoff, 8, &_hdr); - if (hp == NULL) - return 0; - - tuple->src.u.tcp.port = hp->source; - tuple->dst.u.tcp.port = hp->dest; - - return 1; -} - -static int tcp_invert_tuple(struct ip_conntrack_tuple *tuple, - const struct ip_conntrack_tuple *orig) -{ - tuple->src.u.tcp.port = orig->dst.u.tcp.port; - tuple->dst.u.tcp.port = orig->src.u.tcp.port; - return 1; -} - -/* Print out the per-protocol part of the tuple. */ -static int tcp_print_tuple(struct seq_file *s, - const struct ip_conntrack_tuple *tuple) -{ - return seq_printf(s, "sport=%hu dport=%hu ", - ntohs(tuple->src.u.tcp.port), - ntohs(tuple->dst.u.tcp.port)); -} - -/* Print out the private part of the conntrack. */ -static int tcp_print_conntrack(struct seq_file *s, - const struct ip_conntrack *conntrack) -{ - enum tcp_conntrack state; - - read_lock_bh(&tcp_lock); - state = conntrack->proto.tcp.state; - read_unlock_bh(&tcp_lock); - - return seq_printf(s, "%s ", tcp_conntrack_names[state]); -} - -#if defined(CONFIG_IP_NF_CONNTRACK_NETLINK) || \ - defined(CONFIG_IP_NF_CONNTRACK_NETLINK_MODULE) -static int tcp_to_nfattr(struct sk_buff *skb, struct nfattr *nfa, - const struct ip_conntrack *ct) -{ - struct nfattr *nest_parms; - - read_lock_bh(&tcp_lock); - nest_parms = NFA_NEST(skb, CTA_PROTOINFO_TCP); - NFA_PUT(skb, CTA_PROTOINFO_TCP_STATE, sizeof(u_int8_t), - &ct->proto.tcp.state); - read_unlock_bh(&tcp_lock); - - NFA_NEST_END(skb, nest_parms); - - return 0; - -nfattr_failure: - read_unlock_bh(&tcp_lock); - return -1; -} - -static const size_t cta_min_tcp[CTA_PROTOINFO_TCP_MAX] = { - [CTA_PROTOINFO_TCP_STATE-1] = sizeof(u_int8_t), -}; - -static int nfattr_to_tcp(struct nfattr *cda[], struct ip_conntrack *ct) -{ - struct nfattr *attr = cda[CTA_PROTOINFO_TCP-1]; - struct nfattr *tb[CTA_PROTOINFO_TCP_MAX]; - - /* updates could not contain anything about the private - * protocol info, in that case skip the parsing */ - if (!attr) - return 0; - - nfattr_parse_nested(tb, CTA_PROTOINFO_TCP_MAX, attr); - - if (nfattr_bad_size(tb, CTA_PROTOINFO_TCP_MAX, cta_min_tcp)) - return -EINVAL; - - if (!tb[CTA_PROTOINFO_TCP_STATE-1]) - return -EINVAL; - - write_lock_bh(&tcp_lock); - ct->proto.tcp.state = - *(u_int8_t *)NFA_DATA(tb[CTA_PROTOINFO_TCP_STATE-1]); - write_unlock_bh(&tcp_lock); - - return 0; -} -#endif - -static unsigned int get_conntrack_index(const struct tcphdr *tcph) -{ - if (tcph->rst) return TCP_RST_SET; - else if (tcph->syn) return (tcph->ack ? TCP_SYNACK_SET : TCP_SYN_SET); - else if (tcph->fin) return TCP_FIN_SET; - else if (tcph->ack) return TCP_ACK_SET; - else return TCP_NONE_SET; -} - -/* TCP connection tracking based on 'Real Stateful TCP Packet Filtering - in IP Filter' by Guido van Rooij. - - http://www.nluug.nl/events/sane2000/papers.html - http://www.iae.nl/users/guido/papers/tcp_filtering.ps.gz - - The boundaries and the conditions are changed according to RFC793: - the packet must intersect the window (i.e. segments may be - after the right or before the left edge) and thus receivers may ACK - segments after the right edge of the window. - - td_maxend = max(sack + max(win,1)) seen in reply packets - td_maxwin = max(max(win, 1)) + (sack - ack) seen in sent packets - td_maxwin += seq + len - sender.td_maxend - if seq + len > sender.td_maxend - td_end = max(seq + len) seen in sent packets - - I. Upper bound for valid data: seq <= sender.td_maxend - II. Lower bound for valid data: seq + len >= sender.td_end - receiver.td_maxwin - III. Upper bound for valid ack: sack <= receiver.td_end - IV. Lower bound for valid ack: ack >= receiver.td_end - MAXACKWINDOW - - where sack is the highest right edge of sack block found in the packet. - - The upper bound limit for a valid ack is not ignored - - we doesn't have to deal with fragments. -*/ - -static inline __u32 segment_seq_plus_len(__u32 seq, - size_t len, - struct iphdr *iph, - struct tcphdr *tcph) -{ - return (seq + len - (iph->ihl + tcph->doff)*4 - + (tcph->syn ? 1 : 0) + (tcph->fin ? 1 : 0)); -} - -/* Fixme: what about big packets? */ -#define MAXACKWINCONST 66000 -#define MAXACKWINDOW(sender) \ - ((sender)->td_maxwin > MAXACKWINCONST ? (sender)->td_maxwin \ - : MAXACKWINCONST) - -/* - * Simplified tcp_parse_options routine from tcp_input.c - */ -static void tcp_options(const struct sk_buff *skb, - struct iphdr *iph, - struct tcphdr *tcph, - struct ip_ct_tcp_state *state) -{ - unsigned char buff[(15 * 4) - sizeof(struct tcphdr)]; - unsigned char *ptr; - int length = (tcph->doff*4) - sizeof(struct tcphdr); - - if (!length) - return; - - ptr = skb_header_pointer(skb, - (iph->ihl * 4) + sizeof(struct tcphdr), - length, buff); - BUG_ON(ptr == NULL); - - state->td_scale = - state->flags = 0; - - while (length > 0) { - int opcode=*ptr++; - int opsize; - - switch (opcode) { - case TCPOPT_EOL: - return; - case TCPOPT_NOP: /* Ref: RFC 793 section 3.1 */ - length--; - continue; - default: - opsize=*ptr++; - if (opsize < 2) /* "silly options" */ - return; - if (opsize > length) - break; /* don't parse partial options */ - - if (opcode == TCPOPT_SACK_PERM - && opsize == TCPOLEN_SACK_PERM) - state->flags |= IP_CT_TCP_FLAG_SACK_PERM; - else if (opcode == TCPOPT_WINDOW - && opsize == TCPOLEN_WINDOW) { - state->td_scale = *(u_int8_t *)ptr; - - if (state->td_scale > 14) { - /* See RFC1323 */ - state->td_scale = 14; - } - state->flags |= - IP_CT_TCP_FLAG_WINDOW_SCALE; - } - ptr += opsize - 2; - length -= opsize; - } - } -} - -static void tcp_sack(const struct sk_buff *skb, - struct iphdr *iph, - struct tcphdr *tcph, - __u32 *sack) -{ - unsigned char buff[(15 * 4) - sizeof(struct tcphdr)]; - unsigned char *ptr; - int length = (tcph->doff*4) - sizeof(struct tcphdr); - __u32 tmp; - - if (!length) - return; - - ptr = skb_header_pointer(skb, - (iph->ihl * 4) + sizeof(struct tcphdr), - length, buff); - BUG_ON(ptr == NULL); - - /* Fast path for timestamp-only option */ - if (length == TCPOLEN_TSTAMP_ALIGNED*4 - && *(__be32 *)ptr == - __constant_htonl((TCPOPT_NOP << 24) - | (TCPOPT_NOP << 16) - | (TCPOPT_TIMESTAMP << 8) - | TCPOLEN_TIMESTAMP)) - return; - - while (length > 0) { - int opcode=*ptr++; - int opsize, i; - - switch (opcode) { - case TCPOPT_EOL: - return; - case TCPOPT_NOP: /* Ref: RFC 793 section 3.1 */ - length--; - continue; - default: - opsize=*ptr++; - if (opsize < 2) /* "silly options" */ - return; - if (opsize > length) - break; /* don't parse partial options */ - - if (opcode == TCPOPT_SACK - && opsize >= (TCPOLEN_SACK_BASE - + TCPOLEN_SACK_PERBLOCK) - && !((opsize - TCPOLEN_SACK_BASE) - % TCPOLEN_SACK_PERBLOCK)) { - for (i = 0; - i < (opsize - TCPOLEN_SACK_BASE); - i += TCPOLEN_SACK_PERBLOCK) { - tmp = ntohl(*((__be32 *)(ptr+i)+1)); - - if (after(tmp, *sack)) - *sack = tmp; - } - return; - } - ptr += opsize - 2; - length -= opsize; - } - } -} - -static int tcp_in_window(struct ip_ct_tcp *state, - enum ip_conntrack_dir dir, - unsigned int index, - const struct sk_buff *skb, - struct iphdr *iph, - struct tcphdr *tcph) -{ - struct ip_ct_tcp_state *sender = &state->seen[dir]; - struct ip_ct_tcp_state *receiver = &state->seen[!dir]; - __u32 seq, ack, sack, end, win, swin; - int res; - - /* - * Get the required data from the packet. - */ - seq = ntohl(tcph->seq); - ack = sack = ntohl(tcph->ack_seq); - win = ntohs(tcph->window); - end = segment_seq_plus_len(seq, skb->len, iph, tcph); - - if (receiver->flags & IP_CT_TCP_FLAG_SACK_PERM) - tcp_sack(skb, iph, tcph, &sack); - - DEBUGP("tcp_in_window: START\n"); - DEBUGP("tcp_in_window: src=%u.%u.%u.%u:%hu dst=%u.%u.%u.%u:%hu " - "seq=%u ack=%u sack=%u win=%u end=%u\n", - NIPQUAD(iph->saddr), ntohs(tcph->source), - NIPQUAD(iph->daddr), ntohs(tcph->dest), - seq, ack, sack, win, end); - DEBUGP("tcp_in_window: sender end=%u maxend=%u maxwin=%u scale=%i " - "receiver end=%u maxend=%u maxwin=%u scale=%i\n", - sender->td_end, sender->td_maxend, sender->td_maxwin, - sender->td_scale, - receiver->td_end, receiver->td_maxend, receiver->td_maxwin, - receiver->td_scale); - - if (sender->td_end == 0) { - /* - * Initialize sender data. - */ - if (tcph->syn && tcph->ack) { - /* - * Outgoing SYN-ACK in reply to a SYN. - */ - sender->td_end = - sender->td_maxend = end; - sender->td_maxwin = (win == 0 ? 1 : win); - - tcp_options(skb, iph, tcph, sender); - /* - * RFC 1323: - * Both sides must send the Window Scale option - * to enable window scaling in either direction. - */ - if (!(sender->flags & IP_CT_TCP_FLAG_WINDOW_SCALE - && receiver->flags & IP_CT_TCP_FLAG_WINDOW_SCALE)) - sender->td_scale = - receiver->td_scale = 0; - } else { - /* - * We are in the middle of a connection, - * its history is lost for us. - * Let's try to use the data from the packet. - */ - sender->td_end = end; - sender->td_maxwin = (win == 0 ? 1 : win); - sender->td_maxend = end + sender->td_maxwin; - } - } else if (((state->state == TCP_CONNTRACK_SYN_SENT - && dir == IP_CT_DIR_ORIGINAL) - || (state->state == TCP_CONNTRACK_SYN_RECV - && dir == IP_CT_DIR_REPLY)) - && after(end, sender->td_end)) { - /* - * RFC 793: "if a TCP is reinitialized ... then it need - * not wait at all; it must only be sure to use sequence - * numbers larger than those recently used." - */ - sender->td_end = - sender->td_maxend = end; - sender->td_maxwin = (win == 0 ? 1 : win); - - tcp_options(skb, iph, tcph, sender); - } - - if (!(tcph->ack)) { - /* - * If there is no ACK, just pretend it was set and OK. - */ - ack = sack = receiver->td_end; - } else if (((tcp_flag_word(tcph) & (TCP_FLAG_ACK|TCP_FLAG_RST)) == - (TCP_FLAG_ACK|TCP_FLAG_RST)) - && (ack == 0)) { - /* - * Broken TCP stacks, that set ACK in RST packets as well - * with zero ack value. - */ - ack = sack = receiver->td_end; - } - - if (seq == end - && (!tcph->rst - || (seq == 0 && state->state == TCP_CONNTRACK_SYN_SENT))) - /* - * Packets contains no data: we assume it is valid - * and check the ack value only. - * However RST segments are always validated by their - * SEQ number, except when seq == 0 (reset sent answering - * SYN. - */ - seq = end = sender->td_end; - - DEBUGP("tcp_in_window: src=%u.%u.%u.%u:%hu dst=%u.%u.%u.%u:%hu " - "seq=%u ack=%u sack =%u win=%u end=%u\n", - NIPQUAD(iph->saddr), ntohs(tcph->source), - NIPQUAD(iph->daddr), ntohs(tcph->dest), - seq, ack, sack, win, end); - DEBUGP("tcp_in_window: sender end=%u maxend=%u maxwin=%u scale=%i " - "receiver end=%u maxend=%u maxwin=%u scale=%i\n", - sender->td_end, sender->td_maxend, sender->td_maxwin, - sender->td_scale, - receiver->td_end, receiver->td_maxend, receiver->td_maxwin, - receiver->td_scale); - - DEBUGP("tcp_in_window: I=%i II=%i III=%i IV=%i\n", - before(seq, sender->td_maxend + 1), - after(end, sender->td_end - receiver->td_maxwin - 1), - before(sack, receiver->td_end + 1), - after(ack, receiver->td_end - MAXACKWINDOW(sender))); - - if (before(seq, sender->td_maxend + 1) && - after(end, sender->td_end - receiver->td_maxwin - 1) && - before(sack, receiver->td_end + 1) && - after(ack, receiver->td_end - MAXACKWINDOW(sender))) { - /* - * Take into account window scaling (RFC 1323). - */ - if (!tcph->syn) - win <<= sender->td_scale; - - /* - * Update sender data. - */ - swin = win + (sack - ack); - if (sender->td_maxwin < swin) - sender->td_maxwin = swin; - if (after(end, sender->td_end)) - sender->td_end = end; - /* - * Update receiver data. - */ - if (after(end, sender->td_maxend)) - receiver->td_maxwin += end - sender->td_maxend; - if (after(sack + win, receiver->td_maxend - 1)) { - receiver->td_maxend = sack + win; - if (win == 0) - receiver->td_maxend++; - } - - /* - * Check retransmissions. - */ - if (index == TCP_ACK_SET) { - if (state->last_dir == dir - && state->last_seq == seq - && state->last_ack == ack - && state->last_end == end - && state->last_win == win) - state->retrans++; - else { - state->last_dir = dir; - state->last_seq = seq; - state->last_ack = ack; - state->last_end = end; - state->last_win = win; - state->retrans = 0; - } - } - res = 1; - } else { - res = 0; - if (sender->flags & IP_CT_TCP_FLAG_BE_LIBERAL || - ip_ct_tcp_be_liberal) - res = 1; - if (!res && LOG_INVALID(IPPROTO_TCP)) - nf_log_packet(PF_INET, 0, skb, NULL, NULL, NULL, - "ip_ct_tcp: %s ", - before(seq, sender->td_maxend + 1) ? - after(end, sender->td_end - receiver->td_maxwin - 1) ? - before(sack, receiver->td_end + 1) ? - after(ack, receiver->td_end - MAXACKWINDOW(sender)) ? "BUG" - : "ACK is under the lower bound (possible overly delayed ACK)" - : "ACK is over the upper bound (ACKed data not seen yet)" - : "SEQ is under the lower bound (already ACKed data retransmitted)" - : "SEQ is over the upper bound (over the window of the receiver)"); - } - - DEBUGP("tcp_in_window: res=%i sender end=%u maxend=%u maxwin=%u " - "receiver end=%u maxend=%u maxwin=%u\n", - res, sender->td_end, sender->td_maxend, sender->td_maxwin, - receiver->td_end, receiver->td_maxend, receiver->td_maxwin); - - return res; -} - -#ifdef CONFIG_IP_NF_NAT_NEEDED -/* Update sender->td_end after NAT successfully mangled the packet */ -void ip_conntrack_tcp_update(struct sk_buff *skb, - struct ip_conntrack *conntrack, - enum ip_conntrack_dir dir) -{ - struct iphdr *iph = skb->nh.iph; - struct tcphdr *tcph = (void *)skb->nh.iph + skb->nh.iph->ihl*4; - __u32 end; -#ifdef DEBUGP_VARS - struct ip_ct_tcp_state *sender = &conntrack->proto.tcp.seen[dir]; - struct ip_ct_tcp_state *receiver = &conntrack->proto.tcp.seen[!dir]; -#endif - - end = segment_seq_plus_len(ntohl(tcph->seq), skb->len, iph, tcph); - - write_lock_bh(&tcp_lock); - /* - * We have to worry for the ack in the reply packet only... - */ - if (after(end, conntrack->proto.tcp.seen[dir].td_end)) - conntrack->proto.tcp.seen[dir].td_end = end; - conntrack->proto.tcp.last_end = end; - write_unlock_bh(&tcp_lock); - DEBUGP("tcp_update: sender end=%u maxend=%u maxwin=%u scale=%i " - "receiver end=%u maxend=%u maxwin=%u scale=%i\n", - sender->td_end, sender->td_maxend, sender->td_maxwin, - sender->td_scale, - receiver->td_end, receiver->td_maxend, receiver->td_maxwin, - receiver->td_scale); -} - -#endif - -#define TH_FIN 0x01 -#define TH_SYN 0x02 -#define TH_RST 0x04 -#define TH_PUSH 0x08 -#define TH_ACK 0x10 -#define TH_URG 0x20 -#define TH_ECE 0x40 -#define TH_CWR 0x80 - -/* table of valid flag combinations - ECE and CWR are always valid */ -static const u8 tcp_valid_flags[(TH_FIN|TH_SYN|TH_RST|TH_PUSH|TH_ACK|TH_URG) + 1] = -{ - [TH_SYN] = 1, - [TH_SYN|TH_PUSH] = 1, - [TH_SYN|TH_URG] = 1, - [TH_SYN|TH_PUSH|TH_URG] = 1, - [TH_SYN|TH_ACK] = 1, - [TH_SYN|TH_ACK|TH_PUSH] = 1, - [TH_RST] = 1, - [TH_RST|TH_ACK] = 1, - [TH_RST|TH_ACK|TH_PUSH] = 1, - [TH_FIN|TH_ACK] = 1, - [TH_ACK] = 1, - [TH_ACK|TH_PUSH] = 1, - [TH_ACK|TH_URG] = 1, - [TH_ACK|TH_URG|TH_PUSH] = 1, - [TH_FIN|TH_ACK|TH_PUSH] = 1, - [TH_FIN|TH_ACK|TH_URG] = 1, - [TH_FIN|TH_ACK|TH_URG|TH_PUSH] = 1, -}; - -/* Protect conntrack agaist broken packets. Code taken from ipt_unclean.c. */ -static int tcp_error(struct sk_buff *skb, - enum ip_conntrack_info *ctinfo, - unsigned int hooknum) -{ - struct iphdr *iph = skb->nh.iph; - struct tcphdr _tcph, *th; - unsigned int tcplen = skb->len - iph->ihl * 4; - u_int8_t tcpflags; - - /* Smaller that minimal TCP header? */ - th = skb_header_pointer(skb, iph->ihl * 4, - sizeof(_tcph), &_tcph); - if (th == NULL) { - if (LOG_INVALID(IPPROTO_TCP)) - nf_log_packet(PF_INET, 0, skb, NULL, NULL, NULL, - "ip_ct_tcp: short packet "); - return -NF_ACCEPT; - } - - /* Not whole TCP header or malformed packet */ - if (th->doff*4 < sizeof(struct tcphdr) || tcplen < th->doff*4) { - if (LOG_INVALID(IPPROTO_TCP)) - nf_log_packet(PF_INET, 0, skb, NULL, NULL, NULL, - "ip_ct_tcp: truncated/malformed packet "); - return -NF_ACCEPT; - } - - /* Checksum invalid? Ignore. - * We skip checking packets on the outgoing path - * because it is assumed to be correct. - */ - /* FIXME: Source route IP option packets --RR */ - if (ip_conntrack_checksum && hooknum == NF_IP_PRE_ROUTING && - nf_ip_checksum(skb, hooknum, iph->ihl * 4, IPPROTO_TCP)) { - if (LOG_INVALID(IPPROTO_TCP)) - nf_log_packet(PF_INET, 0, skb, NULL, NULL, NULL, - "ip_ct_tcp: bad TCP checksum "); - return -NF_ACCEPT; - } - - /* Check TCP flags. */ - tcpflags = (((u_int8_t *)th)[13] & ~(TH_ECE|TH_CWR)); - if (!tcp_valid_flags[tcpflags]) { - if (LOG_INVALID(IPPROTO_TCP)) - nf_log_packet(PF_INET, 0, skb, NULL, NULL, NULL, - "ip_ct_tcp: invalid TCP flag combination "); - return -NF_ACCEPT; - } - - return NF_ACCEPT; -} - -/* Returns verdict for packet, or -1 for invalid. */ -static int tcp_packet(struct ip_conntrack *conntrack, - const struct sk_buff *skb, - enum ip_conntrack_info ctinfo) -{ - enum tcp_conntrack new_state, old_state; - enum ip_conntrack_dir dir; - struct iphdr *iph = skb->nh.iph; - struct tcphdr *th, _tcph; - unsigned long timeout; - unsigned int index; - - th = skb_header_pointer(skb, iph->ihl * 4, - sizeof(_tcph), &_tcph); - BUG_ON(th == NULL); - - write_lock_bh(&tcp_lock); - old_state = conntrack->proto.tcp.state; - dir = CTINFO2DIR(ctinfo); - index = get_conntrack_index(th); - new_state = tcp_conntracks[dir][index][old_state]; - - switch (new_state) { - case TCP_CONNTRACK_IGNORE: - /* Ignored packets: - * - * a) SYN in ORIGINAL - * b) SYN/ACK in REPLY - * c) ACK in reply direction after initial SYN in original. - */ - if (index == TCP_SYNACK_SET - && conntrack->proto.tcp.last_index == TCP_SYN_SET - && conntrack->proto.tcp.last_dir != dir - && ntohl(th->ack_seq) == - conntrack->proto.tcp.last_end) { - /* This SYN/ACK acknowledges a SYN that we earlier - * ignored as invalid. This means that the client and - * the server are both in sync, while the firewall is - * not. We kill this session and block the SYN/ACK so - * that the client cannot but retransmit its SYN and - * thus initiate a clean new session. - */ - write_unlock_bh(&tcp_lock); - if (LOG_INVALID(IPPROTO_TCP)) - nf_log_packet(PF_INET, 0, skb, NULL, NULL, - NULL, "ip_ct_tcp: " - "killing out of sync session "); - if (del_timer(&conntrack->timeout)) - conntrack->timeout.function((unsigned long) - conntrack); - return -NF_DROP; - } - conntrack->proto.tcp.last_index = index; - conntrack->proto.tcp.last_dir = dir; - conntrack->proto.tcp.last_seq = ntohl(th->seq); - conntrack->proto.tcp.last_end = - segment_seq_plus_len(ntohl(th->seq), skb->len, iph, th); - - write_unlock_bh(&tcp_lock); - if (LOG_INVALID(IPPROTO_TCP)) - nf_log_packet(PF_INET, 0, skb, NULL, NULL, NULL, - "ip_ct_tcp: invalid packet ignored "); - return NF_ACCEPT; - case TCP_CONNTRACK_MAX: - /* Invalid packet */ - DEBUGP("ip_ct_tcp: Invalid dir=%i index=%u ostate=%u\n", - dir, get_conntrack_index(th), - old_state); - write_unlock_bh(&tcp_lock); - if (LOG_INVALID(IPPROTO_TCP)) - nf_log_packet(PF_INET, 0, skb, NULL, NULL, NULL, - "ip_ct_tcp: invalid state "); - return -NF_ACCEPT; - case TCP_CONNTRACK_SYN_SENT: - if (old_state < TCP_CONNTRACK_TIME_WAIT) - break; - if ((conntrack->proto.tcp.seen[dir].flags & - IP_CT_TCP_FLAG_CLOSE_INIT) - || after(ntohl(th->seq), - conntrack->proto.tcp.seen[dir].td_end)) { - /* Attempt to reopen a closed connection. - * Delete this connection and look up again. */ - write_unlock_bh(&tcp_lock); - if (del_timer(&conntrack->timeout)) - conntrack->timeout.function((unsigned long) - conntrack); - return -NF_REPEAT; - } else { - write_unlock_bh(&tcp_lock); - if (LOG_INVALID(IPPROTO_TCP)) - nf_log_packet(PF_INET, 0, skb, NULL, NULL, - NULL, "ip_ct_tcp: invalid SYN"); - return -NF_ACCEPT; - } - case TCP_CONNTRACK_CLOSE: - if (index == TCP_RST_SET - && ((test_bit(IPS_SEEN_REPLY_BIT, &conntrack->status) - && conntrack->proto.tcp.last_index == TCP_SYN_SET) - || (!test_bit(IPS_ASSURED_BIT, &conntrack->status) - && conntrack->proto.tcp.last_index == TCP_ACK_SET)) - && ntohl(th->ack_seq) == conntrack->proto.tcp.last_end) { - /* RST sent to invalid SYN or ACK we had let through - * at a) and c) above: - * - * a) SYN was in window then - * c) we hold a half-open connection. - * - * Delete our connection entry. - * We skip window checking, because packet might ACK - * segments we ignored. */ - goto in_window; - } - /* Just fall through */ - default: - /* Keep compilers happy. */ - break; - } - - if (!tcp_in_window(&conntrack->proto.tcp, dir, index, - skb, iph, th)) { - write_unlock_bh(&tcp_lock); - return -NF_ACCEPT; - } - in_window: - /* From now on we have got in-window packets */ - conntrack->proto.tcp.last_index = index; - - DEBUGP("tcp_conntracks: src=%u.%u.%u.%u:%hu dst=%u.%u.%u.%u:%hu " - "syn=%i ack=%i fin=%i rst=%i old=%i new=%i\n", - NIPQUAD(iph->saddr), ntohs(th->source), - NIPQUAD(iph->daddr), ntohs(th->dest), - (th->syn ? 1 : 0), (th->ack ? 1 : 0), - (th->fin ? 1 : 0), (th->rst ? 1 : 0), - old_state, new_state); - - conntrack->proto.tcp.state = new_state; - if (old_state != new_state - && (new_state == TCP_CONNTRACK_FIN_WAIT - || new_state == TCP_CONNTRACK_CLOSE)) - conntrack->proto.tcp.seen[dir].flags |= IP_CT_TCP_FLAG_CLOSE_INIT; - timeout = conntrack->proto.tcp.retrans >= ip_ct_tcp_max_retrans - && *tcp_timeouts[new_state] > ip_ct_tcp_timeout_max_retrans - ? ip_ct_tcp_timeout_max_retrans : *tcp_timeouts[new_state]; - write_unlock_bh(&tcp_lock); - - ip_conntrack_event_cache(IPCT_PROTOINFO_VOLATILE, skb); - if (new_state != old_state) - ip_conntrack_event_cache(IPCT_PROTOINFO, skb); - - if (!test_bit(IPS_SEEN_REPLY_BIT, &conntrack->status)) { - /* If only reply is a RST, we can consider ourselves not to - have an established connection: this is a fairly common - problem case, so we can delete the conntrack - immediately. --RR */ - if (th->rst) { - if (del_timer(&conntrack->timeout)) - conntrack->timeout.function((unsigned long) - conntrack); - return NF_ACCEPT; - } - } else if (!test_bit(IPS_ASSURED_BIT, &conntrack->status) - && (old_state == TCP_CONNTRACK_SYN_RECV - || old_state == TCP_CONNTRACK_ESTABLISHED) - && new_state == TCP_CONNTRACK_ESTABLISHED) { - /* Set ASSURED if we see see valid ack in ESTABLISHED - after SYN_RECV or a valid answer for a picked up - connection. */ - set_bit(IPS_ASSURED_BIT, &conntrack->status); - ip_conntrack_event_cache(IPCT_STATUS, skb); - } - ip_ct_refresh_acct(conntrack, ctinfo, skb, timeout); - - return NF_ACCEPT; -} - -/* Called when a new connection for this protocol found. */ -static int tcp_new(struct ip_conntrack *conntrack, - const struct sk_buff *skb) -{ - enum tcp_conntrack new_state; - struct iphdr *iph = skb->nh.iph; - struct tcphdr *th, _tcph; -#ifdef DEBUGP_VARS - struct ip_ct_tcp_state *sender = &conntrack->proto.tcp.seen[0]; - struct ip_ct_tcp_state *receiver = &conntrack->proto.tcp.seen[1]; -#endif - - th = skb_header_pointer(skb, iph->ihl * 4, - sizeof(_tcph), &_tcph); - BUG_ON(th == NULL); - - /* Don't need lock here: this conntrack not in circulation yet */ - new_state - = tcp_conntracks[0][get_conntrack_index(th)] - [TCP_CONNTRACK_NONE]; - - /* Invalid: delete conntrack */ - if (new_state >= TCP_CONNTRACK_MAX) { - DEBUGP("ip_ct_tcp: invalid new deleting.\n"); - return 0; - } - - if (new_state == TCP_CONNTRACK_SYN_SENT) { - /* SYN packet */ - conntrack->proto.tcp.seen[0].td_end = - segment_seq_plus_len(ntohl(th->seq), skb->len, - iph, th); - conntrack->proto.tcp.seen[0].td_maxwin = ntohs(th->window); - if (conntrack->proto.tcp.seen[0].td_maxwin == 0) - conntrack->proto.tcp.seen[0].td_maxwin = 1; - conntrack->proto.tcp.seen[0].td_maxend = - conntrack->proto.tcp.seen[0].td_end; - - tcp_options(skb, iph, th, &conntrack->proto.tcp.seen[0]); - conntrack->proto.tcp.seen[1].flags = 0; - } else if (ip_ct_tcp_loose == 0) { - /* Don't try to pick up connections. */ - return 0; - } else { - /* - * We are in the middle of a connection, - * its history is lost for us. - * Let's try to use the data from the packet. - */ - conntrack->proto.tcp.seen[0].td_end = - segment_seq_plus_len(ntohl(th->seq), skb->len, - iph, th); - conntrack->proto.tcp.seen[0].td_maxwin = ntohs(th->window); - if (conntrack->proto.tcp.seen[0].td_maxwin == 0) - conntrack->proto.tcp.seen[0].td_maxwin = 1; - conntrack->proto.tcp.seen[0].td_maxend = - conntrack->proto.tcp.seen[0].td_end + - conntrack->proto.tcp.seen[0].td_maxwin; - conntrack->proto.tcp.seen[0].td_scale = 0; - - /* We assume SACK and liberal window checking to handle - * window scaling */ - conntrack->proto.tcp.seen[0].flags = - conntrack->proto.tcp.seen[1].flags = IP_CT_TCP_FLAG_SACK_PERM | - IP_CT_TCP_FLAG_BE_LIBERAL; - } - - conntrack->proto.tcp.seen[1].td_end = 0; - conntrack->proto.tcp.seen[1].td_maxend = 0; - conntrack->proto.tcp.seen[1].td_maxwin = 1; - conntrack->proto.tcp.seen[1].td_scale = 0; - - /* tcp_packet will set them */ - conntrack->proto.tcp.state = TCP_CONNTRACK_NONE; - conntrack->proto.tcp.last_index = TCP_NONE_SET; - - DEBUGP("tcp_new: sender end=%u maxend=%u maxwin=%u scale=%i " - "receiver end=%u maxend=%u maxwin=%u scale=%i\n", - sender->td_end, sender->td_maxend, sender->td_maxwin, - sender->td_scale, - receiver->td_end, receiver->td_maxend, receiver->td_maxwin, - receiver->td_scale); - return 1; -} - -struct ip_conntrack_protocol ip_conntrack_protocol_tcp = -{ - .proto = IPPROTO_TCP, - .name = "tcp", - .pkt_to_tuple = tcp_pkt_to_tuple, - .invert_tuple = tcp_invert_tuple, - .print_tuple = tcp_print_tuple, - .print_conntrack = tcp_print_conntrack, - .packet = tcp_packet, - .new = tcp_new, - .error = tcp_error, -#if defined(CONFIG_IP_NF_CONNTRACK_NETLINK) || \ - defined(CONFIG_IP_NF_CONNTRACK_NETLINK_MODULE) - .to_nfattr = tcp_to_nfattr, - .from_nfattr = nfattr_to_tcp, - .tuple_to_nfattr = ip_ct_port_tuple_to_nfattr, - .nfattr_to_tuple = ip_ct_port_nfattr_to_tuple, -#endif -}; |