diff options
Diffstat (limited to 'net/ipv4/netfilter/ip_nat_helper.c')
-rw-r--r-- | net/ipv4/netfilter/ip_nat_helper.c | 436 |
1 files changed, 0 insertions, 436 deletions
diff --git a/net/ipv4/netfilter/ip_nat_helper.c b/net/ipv4/netfilter/ip_nat_helper.c deleted file mode 100644 index 4cddc295174..00000000000 --- a/net/ipv4/netfilter/ip_nat_helper.c +++ /dev/null @@ -1,436 +0,0 @@ -/* ip_nat_helper.c - generic support functions for NAT helpers - * - * (C) 2000-2002 Harald Welte <laforge@netfilter.org> - * (C) 2003-2004 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. - * - * 14 Jan 2002 Harald Welte <laforge@gnumonks.org>: - * - add support for SACK adjustment - * 14 Mar 2002 Harald Welte <laforge@gnumonks.org>: - * - merge SACK support into newnat API - * 16 Aug 2002 Brian J. Murrell <netfilter@interlinx.bc.ca>: - * - make ip_nat_resize_packet more generic (TCP and UDP) - * - add ip_nat_mangle_udp_packet - */ -#include <linux/module.h> -#include <linux/kmod.h> -#include <linux/types.h> -#include <linux/timer.h> -#include <linux/skbuff.h> -#include <linux/netfilter_ipv4.h> -#include <net/checksum.h> -#include <net/icmp.h> -#include <net/ip.h> -#include <net/tcp.h> -#include <net/udp.h> - -#include <linux/netfilter_ipv4/ip_conntrack.h> -#include <linux/netfilter_ipv4/ip_conntrack_helper.h> -#include <linux/netfilter_ipv4/ip_nat.h> -#include <linux/netfilter_ipv4/ip_nat_protocol.h> -#include <linux/netfilter_ipv4/ip_nat_core.h> -#include <linux/netfilter_ipv4/ip_nat_helper.h> - -#if 0 -#define DEBUGP printk -#define DUMP_OFFSET(x) printk("offset_before=%d, offset_after=%d, correction_pos=%u\n", x->offset_before, x->offset_after, x->correction_pos); -#else -#define DEBUGP(format, args...) -#define DUMP_OFFSET(x) -#endif - -static DEFINE_SPINLOCK(ip_nat_seqofs_lock); - -/* Setup TCP sequence correction given this change at this sequence */ -static inline void -adjust_tcp_sequence(u32 seq, - int sizediff, - struct ip_conntrack *ct, - enum ip_conntrack_info ctinfo) -{ - int dir; - struct ip_nat_seq *this_way, *other_way; - - DEBUGP("ip_nat_resize_packet: old_size = %u, new_size = %u\n", - (*skb)->len, new_size); - - dir = CTINFO2DIR(ctinfo); - - this_way = &ct->nat.info.seq[dir]; - other_way = &ct->nat.info.seq[!dir]; - - DEBUGP("ip_nat_resize_packet: Seq_offset before: "); - DUMP_OFFSET(this_way); - - spin_lock_bh(&ip_nat_seqofs_lock); - - /* SYN adjust. If it's uninitialized, or this is after last - * correction, record it: we don't handle more than one - * adjustment in the window, but do deal with common case of a - * retransmit */ - if (this_way->offset_before == this_way->offset_after - || before(this_way->correction_pos, seq)) { - this_way->correction_pos = seq; - this_way->offset_before = this_way->offset_after; - this_way->offset_after += sizediff; - } - spin_unlock_bh(&ip_nat_seqofs_lock); - - DEBUGP("ip_nat_resize_packet: Seq_offset after: "); - DUMP_OFFSET(this_way); -} - -/* Frobs data inside this packet, which is linear. */ -static void mangle_contents(struct sk_buff *skb, - unsigned int dataoff, - unsigned int match_offset, - unsigned int match_len, - const char *rep_buffer, - unsigned int rep_len) -{ - unsigned char *data; - - BUG_ON(skb_is_nonlinear(skb)); - data = skb_network_header(skb) + dataoff; - - /* move post-replacement */ - memmove(data + match_offset + rep_len, - data + match_offset + match_len, - skb->tail - (data + match_offset + match_len)); - - /* insert data from buffer */ - memcpy(data + match_offset, rep_buffer, rep_len); - - /* update skb info */ - if (rep_len > match_len) { - DEBUGP("ip_nat_mangle_packet: Extending packet by " - "%u from %u bytes\n", rep_len - match_len, - skb->len); - skb_put(skb, rep_len - match_len); - } else { - DEBUGP("ip_nat_mangle_packet: Shrinking packet from " - "%u from %u bytes\n", match_len - rep_len, - skb->len); - __skb_trim(skb, skb->len + rep_len - match_len); - } - - /* fix IP hdr checksum information */ - ip_hdr(skb)->tot_len = htons(skb->len); - ip_send_check(ip_hdr(skb)); -} - -/* Unusual, but possible case. */ -static int enlarge_skb(struct sk_buff **pskb, unsigned int extra) -{ - struct sk_buff *nskb; - - if ((*pskb)->len + extra > 65535) - return 0; - - nskb = skb_copy_expand(*pskb, skb_headroom(*pskb), extra, GFP_ATOMIC); - if (!nskb) - return 0; - - /* Transfer socket to new skb. */ - if ((*pskb)->sk) - skb_set_owner_w(nskb, (*pskb)->sk); - kfree_skb(*pskb); - *pskb = nskb; - return 1; -} - -/* Generic function for mangling variable-length address changes inside - * NATed TCP connections (like the PORT XXX,XXX,XXX,XXX,XXX,XXX - * command in FTP). - * - * Takes care about all the nasty sequence number changes, checksumming, - * skb enlargement, ... - * - * */ -int -ip_nat_mangle_tcp_packet(struct sk_buff **pskb, - struct ip_conntrack *ct, - enum ip_conntrack_info ctinfo, - unsigned int match_offset, - unsigned int match_len, - const char *rep_buffer, - unsigned int rep_len) -{ - struct iphdr *iph; - struct tcphdr *tcph; - int oldlen, datalen; - - if (!skb_make_writable(pskb, (*pskb)->len)) - return 0; - - if (rep_len > match_len - && rep_len - match_len > skb_tailroom(*pskb) - && !enlarge_skb(pskb, rep_len - match_len)) - return 0; - - SKB_LINEAR_ASSERT(*pskb); - - iph = ip_hdr(*pskb); - tcph = (void *)iph + iph->ihl*4; - - oldlen = (*pskb)->len - iph->ihl*4; - mangle_contents(*pskb, iph->ihl*4 + tcph->doff*4, - match_offset, match_len, rep_buffer, rep_len); - - datalen = (*pskb)->len - iph->ihl*4; - if ((*pskb)->ip_summed != CHECKSUM_PARTIAL) { - tcph->check = 0; - tcph->check = tcp_v4_check(datalen, - iph->saddr, iph->daddr, - csum_partial((char *)tcph, - datalen, 0)); - } else - nf_proto_csum_replace2(&tcph->check, *pskb, - htons(oldlen), htons(datalen), 1); - - if (rep_len != match_len) { - set_bit(IPS_SEQ_ADJUST_BIT, &ct->status); - adjust_tcp_sequence(ntohl(tcph->seq), - (int)rep_len - (int)match_len, - ct, ctinfo); - /* Tell TCP window tracking about seq change */ - ip_conntrack_tcp_update(*pskb, ct, CTINFO2DIR(ctinfo)); - } - return 1; -} -EXPORT_SYMBOL(ip_nat_mangle_tcp_packet); - -/* Generic function for mangling variable-length address changes inside - * NATed UDP connections (like the CONNECT DATA XXXXX MESG XXXXX INDEX XXXXX - * command in the Amanda protocol) - * - * Takes care about all the nasty sequence number changes, checksumming, - * skb enlargement, ... - * - * XXX - This function could be merged with ip_nat_mangle_tcp_packet which - * should be fairly easy to do. - */ -int -ip_nat_mangle_udp_packet(struct sk_buff **pskb, - struct ip_conntrack *ct, - enum ip_conntrack_info ctinfo, - unsigned int match_offset, - unsigned int match_len, - const char *rep_buffer, - unsigned int rep_len) -{ - struct iphdr *iph; - struct udphdr *udph; - int datalen, oldlen; - - /* UDP helpers might accidentally mangle the wrong packet */ - iph = ip_hdr(*pskb); - if ((*pskb)->len < iph->ihl*4 + sizeof(*udph) + - match_offset + match_len) - return 0; - - if (!skb_make_writable(pskb, (*pskb)->len)) - return 0; - - if (rep_len > match_len - && rep_len - match_len > skb_tailroom(*pskb) - && !enlarge_skb(pskb, rep_len - match_len)) - return 0; - - iph = ip_hdr(*pskb); - udph = (void *)iph + iph->ihl*4; - - oldlen = (*pskb)->len - iph->ihl*4; - mangle_contents(*pskb, iph->ihl*4 + sizeof(*udph), - match_offset, match_len, rep_buffer, rep_len); - - /* update the length of the UDP packet */ - datalen = (*pskb)->len - iph->ihl*4; - udph->len = htons(datalen); - - /* fix udp checksum if udp checksum was previously calculated */ - if (!udph->check && (*pskb)->ip_summed != CHECKSUM_PARTIAL) - return 1; - - if ((*pskb)->ip_summed != CHECKSUM_PARTIAL) { - udph->check = 0; - udph->check = csum_tcpudp_magic(iph->saddr, iph->daddr, - datalen, IPPROTO_UDP, - csum_partial((char *)udph, - datalen, 0)); - if (!udph->check) - udph->check = CSUM_MANGLED_0; - } else - nf_proto_csum_replace2(&udph->check, *pskb, - htons(oldlen), htons(datalen), 1); - return 1; -} -EXPORT_SYMBOL(ip_nat_mangle_udp_packet); - -/* Adjust one found SACK option including checksum correction */ -static void -sack_adjust(struct sk_buff *skb, - struct tcphdr *tcph, - unsigned int sackoff, - unsigned int sackend, - struct ip_nat_seq *natseq) -{ - while (sackoff < sackend) { - struct tcp_sack_block_wire *sack; - __be32 new_start_seq, new_end_seq; - - sack = (void *)skb->data + sackoff; - if (after(ntohl(sack->start_seq) - natseq->offset_before, - natseq->correction_pos)) - new_start_seq = htonl(ntohl(sack->start_seq) - - natseq->offset_after); - else - new_start_seq = htonl(ntohl(sack->start_seq) - - natseq->offset_before); - - if (after(ntohl(sack->end_seq) - natseq->offset_before, - natseq->correction_pos)) - new_end_seq = htonl(ntohl(sack->end_seq) - - natseq->offset_after); - else - new_end_seq = htonl(ntohl(sack->end_seq) - - natseq->offset_before); - - DEBUGP("sack_adjust: start_seq: %d->%d, end_seq: %d->%d\n", - ntohl(sack->start_seq), new_start_seq, - ntohl(sack->end_seq), new_end_seq); - - nf_proto_csum_replace4(&tcph->check, skb, - sack->start_seq, new_start_seq, 0); - nf_proto_csum_replace4(&tcph->check, skb, - sack->end_seq, new_end_seq, 0); - sack->start_seq = new_start_seq; - sack->end_seq = new_end_seq; - sackoff += sizeof(*sack); - } -} - -/* TCP SACK sequence number adjustment */ -static inline unsigned int -ip_nat_sack_adjust(struct sk_buff **pskb, - struct tcphdr *tcph, - struct ip_conntrack *ct, - enum ip_conntrack_info ctinfo) -{ - unsigned int dir, optoff, optend; - - optoff = ip_hdrlen(*pskb) + sizeof(struct tcphdr); - optend = ip_hdrlen(*pskb) + tcph->doff * 4; - - if (!skb_make_writable(pskb, optend)) - return 0; - - dir = CTINFO2DIR(ctinfo); - - while (optoff < optend) { - /* Usually: option, length. */ - unsigned char *op = (*pskb)->data + optoff; - - switch (op[0]) { - case TCPOPT_EOL: - return 1; - case TCPOPT_NOP: - optoff++; - continue; - default: - /* no partial options */ - if (optoff + 1 == optend - || optoff + op[1] > optend - || op[1] < 2) - return 0; - if (op[0] == TCPOPT_SACK - && op[1] >= 2+TCPOLEN_SACK_PERBLOCK - && ((op[1] - 2) % TCPOLEN_SACK_PERBLOCK) == 0) - sack_adjust(*pskb, tcph, optoff+2, - optoff+op[1], - &ct->nat.info.seq[!dir]); - optoff += op[1]; - } - } - return 1; -} - -/* TCP sequence number adjustment. Returns 1 on success, 0 on failure */ -int -ip_nat_seq_adjust(struct sk_buff **pskb, - struct ip_conntrack *ct, - enum ip_conntrack_info ctinfo) -{ - struct tcphdr *tcph; - int dir; - __be32 newseq, newack; - struct ip_nat_seq *this_way, *other_way; - - dir = CTINFO2DIR(ctinfo); - - this_way = &ct->nat.info.seq[dir]; - other_way = &ct->nat.info.seq[!dir]; - - if (!skb_make_writable(pskb, ip_hdrlen(*pskb) + sizeof(*tcph))) - return 0; - - tcph = (void *)(*pskb)->data + ip_hdrlen(*pskb); - if (after(ntohl(tcph->seq), this_way->correction_pos)) - newseq = htonl(ntohl(tcph->seq) + this_way->offset_after); - else - newseq = htonl(ntohl(tcph->seq) + this_way->offset_before); - - if (after(ntohl(tcph->ack_seq) - other_way->offset_before, - other_way->correction_pos)) - newack = htonl(ntohl(tcph->ack_seq) - other_way->offset_after); - else - newack = htonl(ntohl(tcph->ack_seq) - other_way->offset_before); - - nf_proto_csum_replace4(&tcph->check, *pskb, tcph->seq, newseq, 0); - nf_proto_csum_replace4(&tcph->check, *pskb, tcph->ack_seq, newack, 0); - - DEBUGP("Adjusting sequence number from %u->%u, ack from %u->%u\n", - ntohl(tcph->seq), ntohl(newseq), ntohl(tcph->ack_seq), - ntohl(newack)); - - tcph->seq = newseq; - tcph->ack_seq = newack; - - if (!ip_nat_sack_adjust(pskb, tcph, ct, ctinfo)) - return 0; - - ip_conntrack_tcp_update(*pskb, ct, dir); - - return 1; -} -EXPORT_SYMBOL(ip_nat_seq_adjust); - -/* Setup NAT on this expected conntrack so it follows master. */ -/* If we fail to get a free NAT slot, we'll get dropped on confirm */ -void ip_nat_follow_master(struct ip_conntrack *ct, - struct ip_conntrack_expect *exp) -{ - struct ip_nat_range range; - - /* This must be a fresh one. */ - BUG_ON(ct->status & IPS_NAT_DONE_MASK); - - /* Change src to where master sends to */ - range.flags = IP_NAT_RANGE_MAP_IPS; - range.min_ip = range.max_ip - = ct->master->tuplehash[!exp->dir].tuple.dst.ip; - /* hook doesn't matter, but it has to do source manip */ - ip_nat_setup_info(ct, &range, NF_IP_POST_ROUTING); - - /* For DST manip, map port here to where it's expected. */ - range.flags = (IP_NAT_RANGE_MAP_IPS | IP_NAT_RANGE_PROTO_SPECIFIED); - range.min = range.max = exp->saved_proto; - range.min_ip = range.max_ip - = ct->master->tuplehash[!exp->dir].tuple.src.ip; - /* hook doesn't matter, but it has to do destination manip */ - ip_nat_setup_info(ct, &range, NF_IP_PRE_ROUTING); -} -EXPORT_SYMBOL(ip_nat_follow_master); |