Patrick McHardy | c7232c9 | 2012-08-26 19:14:06 +0200 | [diff] [blame] | 1 | /* nf_nat_helper.c - generic support functions for NAT helpers |
Jozsef Kadlecsik | 5b1158e | 2006-12-02 22:07:13 -0800 | [diff] [blame] | 2 | * |
| 3 | * (C) 2000-2002 Harald Welte <laforge@netfilter.org> |
| 4 | * (C) 2003-2006 Netfilter Core Team <coreteam@netfilter.org> |
Patrick McHardy | f229f6c | 2013-04-06 15:24:29 +0200 | [diff] [blame] | 5 | * (C) 2007-2012 Patrick McHardy <kaber@trash.net> |
Jozsef Kadlecsik | 5b1158e | 2006-12-02 22:07:13 -0800 | [diff] [blame] | 6 | * |
| 7 | * This program is free software; you can redistribute it and/or modify |
| 8 | * it under the terms of the GNU General Public License version 2 as |
| 9 | * published by the Free Software Foundation. |
| 10 | */ |
| 11 | #include <linux/module.h> |
Tejun Heo | 5a0e3ad | 2010-03-24 17:04:11 +0900 | [diff] [blame] | 12 | #include <linux/gfp.h> |
Jozsef Kadlecsik | 5b1158e | 2006-12-02 22:07:13 -0800 | [diff] [blame] | 13 | #include <linux/types.h> |
Jozsef Kadlecsik | 5b1158e | 2006-12-02 22:07:13 -0800 | [diff] [blame] | 14 | #include <linux/skbuff.h> |
| 15 | #include <linux/tcp.h> |
| 16 | #include <linux/udp.h> |
Jozsef Kadlecsik | 5b1158e | 2006-12-02 22:07:13 -0800 | [diff] [blame] | 17 | #include <net/tcp.h> |
| 18 | |
Jozsef Kadlecsik | 5b1158e | 2006-12-02 22:07:13 -0800 | [diff] [blame] | 19 | #include <net/netfilter/nf_conntrack.h> |
| 20 | #include <net/netfilter/nf_conntrack_helper.h> |
Pablo Neira Ayuso | 13eae15 | 2007-12-17 22:28:00 -0800 | [diff] [blame] | 21 | #include <net/netfilter/nf_conntrack_ecache.h> |
Jozsef Kadlecsik | 5b1158e | 2006-12-02 22:07:13 -0800 | [diff] [blame] | 22 | #include <net/netfilter/nf_conntrack_expect.h> |
Patrick McHardy | 41d73ec | 2013-08-27 08:50:12 +0200 | [diff] [blame] | 23 | #include <net/netfilter/nf_conntrack_seqadj.h> |
Jozsef Kadlecsik | 5b1158e | 2006-12-02 22:07:13 -0800 | [diff] [blame] | 24 | #include <net/netfilter/nf_nat.h> |
Patrick McHardy | c7232c9 | 2012-08-26 19:14:06 +0200 | [diff] [blame] | 25 | #include <net/netfilter/nf_nat_l3proto.h> |
| 26 | #include <net/netfilter/nf_nat_l4proto.h> |
Jozsef Kadlecsik | 5b1158e | 2006-12-02 22:07:13 -0800 | [diff] [blame] | 27 | #include <net/netfilter/nf_nat_core.h> |
| 28 | #include <net/netfilter/nf_nat_helper.h> |
| 29 | |
Jozsef Kadlecsik | 5b1158e | 2006-12-02 22:07:13 -0800 | [diff] [blame] | 30 | /* Frobs data inside this packet, which is linear. */ |
| 31 | static void mangle_contents(struct sk_buff *skb, |
| 32 | unsigned int dataoff, |
| 33 | unsigned int match_offset, |
| 34 | unsigned int match_len, |
| 35 | const char *rep_buffer, |
| 36 | unsigned int rep_len) |
| 37 | { |
| 38 | unsigned char *data; |
| 39 | |
| 40 | BUG_ON(skb_is_nonlinear(skb)); |
Arnaldo Carvalho de Melo | eddc9ec | 2007-04-20 22:47:35 -0700 | [diff] [blame] | 41 | data = skb_network_header(skb) + dataoff; |
Jozsef Kadlecsik | 5b1158e | 2006-12-02 22:07:13 -0800 | [diff] [blame] | 42 | |
| 43 | /* move post-replacement */ |
| 44 | memmove(data + match_offset + rep_len, |
| 45 | data + match_offset + match_len, |
Simon Horman | 938177e | 2013-05-30 16:39:29 +0000 | [diff] [blame] | 46 | skb_tail_pointer(skb) - (skb_network_header(skb) + dataoff + |
Arnaldo Carvalho de Melo | 27a884d | 2007-04-19 20:29:13 -0700 | [diff] [blame] | 47 | match_offset + match_len)); |
Jozsef Kadlecsik | 5b1158e | 2006-12-02 22:07:13 -0800 | [diff] [blame] | 48 | |
| 49 | /* insert data from buffer */ |
| 50 | memcpy(data + match_offset, rep_buffer, rep_len); |
| 51 | |
| 52 | /* update skb info */ |
| 53 | if (rep_len > match_len) { |
Patrick McHardy | 0d53778 | 2007-07-07 22:39:38 -0700 | [diff] [blame] | 54 | pr_debug("nf_nat_mangle_packet: Extending packet by " |
| 55 | "%u from %u bytes\n", rep_len - match_len, skb->len); |
Jozsef Kadlecsik | 5b1158e | 2006-12-02 22:07:13 -0800 | [diff] [blame] | 56 | skb_put(skb, rep_len - match_len); |
| 57 | } else { |
Patrick McHardy | 0d53778 | 2007-07-07 22:39:38 -0700 | [diff] [blame] | 58 | pr_debug("nf_nat_mangle_packet: Shrinking packet from " |
| 59 | "%u from %u bytes\n", match_len - rep_len, skb->len); |
Jozsef Kadlecsik | 5b1158e | 2006-12-02 22:07:13 -0800 | [diff] [blame] | 60 | __skb_trim(skb, skb->len + rep_len - match_len); |
| 61 | } |
| 62 | |
Patrick McHardy | c7232c9 | 2012-08-26 19:14:06 +0200 | [diff] [blame] | 63 | if (nf_ct_l3num((struct nf_conn *)skb->nfct) == NFPROTO_IPV4) { |
| 64 | /* fix IP hdr checksum information */ |
| 65 | ip_hdr(skb)->tot_len = htons(skb->len); |
| 66 | ip_send_check(ip_hdr(skb)); |
| 67 | } else |
| 68 | ipv6_hdr(skb)->payload_len = |
| 69 | htons(skb->len - sizeof(struct ipv6hdr)); |
Jozsef Kadlecsik | 5b1158e | 2006-12-02 22:07:13 -0800 | [diff] [blame] | 70 | } |
| 71 | |
| 72 | /* Unusual, but possible case. */ |
Herbert Xu | 3db05fe | 2007-10-15 00:53:15 -0700 | [diff] [blame] | 73 | static int enlarge_skb(struct sk_buff *skb, unsigned int extra) |
Jozsef Kadlecsik | 5b1158e | 2006-12-02 22:07:13 -0800 | [diff] [blame] | 74 | { |
Herbert Xu | 3db05fe | 2007-10-15 00:53:15 -0700 | [diff] [blame] | 75 | if (skb->len + extra > 65535) |
Jozsef Kadlecsik | 5b1158e | 2006-12-02 22:07:13 -0800 | [diff] [blame] | 76 | return 0; |
| 77 | |
Herbert Xu | 3db05fe | 2007-10-15 00:53:15 -0700 | [diff] [blame] | 78 | if (pskb_expand_head(skb, 0, extra - skb_tailroom(skb), GFP_ATOMIC)) |
Jozsef Kadlecsik | 5b1158e | 2006-12-02 22:07:13 -0800 | [diff] [blame] | 79 | return 0; |
| 80 | |
Jozsef Kadlecsik | 5b1158e | 2006-12-02 22:07:13 -0800 | [diff] [blame] | 81 | return 1; |
| 82 | } |
| 83 | |
| 84 | /* Generic function for mangling variable-length address changes inside |
| 85 | * NATed TCP connections (like the PORT XXX,XXX,XXX,XXX,XXX,XXX |
| 86 | * command in FTP). |
| 87 | * |
| 88 | * Takes care about all the nasty sequence number changes, checksumming, |
| 89 | * skb enlargement, ... |
| 90 | * |
| 91 | * */ |
Patrick McHardy | 010c0b9 | 2010-02-11 12:27:09 +0100 | [diff] [blame] | 92 | int __nf_nat_mangle_tcp_packet(struct sk_buff *skb, |
| 93 | struct nf_conn *ct, |
| 94 | enum ip_conntrack_info ctinfo, |
Patrick McHardy | 051966c | 2012-08-26 19:14:04 +0200 | [diff] [blame] | 95 | unsigned int protoff, |
Patrick McHardy | 010c0b9 | 2010-02-11 12:27:09 +0100 | [diff] [blame] | 96 | unsigned int match_offset, |
| 97 | unsigned int match_len, |
| 98 | const char *rep_buffer, |
| 99 | unsigned int rep_len, bool adjust) |
Jozsef Kadlecsik | 5b1158e | 2006-12-02 22:07:13 -0800 | [diff] [blame] | 100 | { |
Patrick McHardy | c7232c9 | 2012-08-26 19:14:06 +0200 | [diff] [blame] | 101 | const struct nf_nat_l3proto *l3proto; |
Jozsef Kadlecsik | 5b1158e | 2006-12-02 22:07:13 -0800 | [diff] [blame] | 102 | struct tcphdr *tcph; |
| 103 | int oldlen, datalen; |
| 104 | |
Herbert Xu | 3db05fe | 2007-10-15 00:53:15 -0700 | [diff] [blame] | 105 | if (!skb_make_writable(skb, skb->len)) |
Jozsef Kadlecsik | 5b1158e | 2006-12-02 22:07:13 -0800 | [diff] [blame] | 106 | return 0; |
| 107 | |
| 108 | if (rep_len > match_len && |
Herbert Xu | 3db05fe | 2007-10-15 00:53:15 -0700 | [diff] [blame] | 109 | rep_len - match_len > skb_tailroom(skb) && |
| 110 | !enlarge_skb(skb, rep_len - match_len)) |
Jozsef Kadlecsik | 5b1158e | 2006-12-02 22:07:13 -0800 | [diff] [blame] | 111 | return 0; |
| 112 | |
Herbert Xu | 3db05fe | 2007-10-15 00:53:15 -0700 | [diff] [blame] | 113 | SKB_LINEAR_ASSERT(skb); |
Jozsef Kadlecsik | 5b1158e | 2006-12-02 22:07:13 -0800 | [diff] [blame] | 114 | |
Patrick McHardy | c7232c9 | 2012-08-26 19:14:06 +0200 | [diff] [blame] | 115 | tcph = (void *)skb->data + protoff; |
Jozsef Kadlecsik | 5b1158e | 2006-12-02 22:07:13 -0800 | [diff] [blame] | 116 | |
Patrick McHardy | c7232c9 | 2012-08-26 19:14:06 +0200 | [diff] [blame] | 117 | oldlen = skb->len - protoff; |
| 118 | mangle_contents(skb, protoff + tcph->doff*4, |
Jozsef Kadlecsik | 5b1158e | 2006-12-02 22:07:13 -0800 | [diff] [blame] | 119 | match_offset, match_len, rep_buffer, rep_len); |
| 120 | |
Patrick McHardy | c7232c9 | 2012-08-26 19:14:06 +0200 | [diff] [blame] | 121 | datalen = skb->len - protoff; |
| 122 | |
| 123 | l3proto = __nf_nat_l3proto_find(nf_ct_l3num(ct)); |
| 124 | l3proto->csum_recalc(skb, IPPROTO_TCP, tcph, &tcph->check, |
| 125 | datalen, oldlen); |
Jozsef Kadlecsik | 5b1158e | 2006-12-02 22:07:13 -0800 | [diff] [blame] | 126 | |
Patrick McHardy | 010c0b9 | 2010-02-11 12:27:09 +0100 | [diff] [blame] | 127 | if (adjust && rep_len != match_len) |
Patrick McHardy | 41d73ec | 2013-08-27 08:50:12 +0200 | [diff] [blame] | 128 | nf_ct_seqadj_set(ct, ctinfo, tcph->seq, |
| 129 | (int)rep_len - (int)match_len); |
Patrick McHardy | 010c0b9 | 2010-02-11 12:27:09 +0100 | [diff] [blame] | 130 | |
Jozsef Kadlecsik | 5b1158e | 2006-12-02 22:07:13 -0800 | [diff] [blame] | 131 | return 1; |
| 132 | } |
Patrick McHardy | 010c0b9 | 2010-02-11 12:27:09 +0100 | [diff] [blame] | 133 | EXPORT_SYMBOL(__nf_nat_mangle_tcp_packet); |
Jozsef Kadlecsik | 5b1158e | 2006-12-02 22:07:13 -0800 | [diff] [blame] | 134 | |
| 135 | /* Generic function for mangling variable-length address changes inside |
| 136 | * NATed UDP connections (like the CONNECT DATA XXXXX MESG XXXXX INDEX XXXXX |
| 137 | * command in the Amanda protocol) |
| 138 | * |
| 139 | * Takes care about all the nasty sequence number changes, checksumming, |
| 140 | * skb enlargement, ... |
| 141 | * |
| 142 | * XXX - This function could be merged with nf_nat_mangle_tcp_packet which |
| 143 | * should be fairly easy to do. |
| 144 | */ |
| 145 | int |
Herbert Xu | 3db05fe | 2007-10-15 00:53:15 -0700 | [diff] [blame] | 146 | nf_nat_mangle_udp_packet(struct sk_buff *skb, |
Jozsef Kadlecsik | 5b1158e | 2006-12-02 22:07:13 -0800 | [diff] [blame] | 147 | struct nf_conn *ct, |
| 148 | enum ip_conntrack_info ctinfo, |
Patrick McHardy | 051966c | 2012-08-26 19:14:04 +0200 | [diff] [blame] | 149 | unsigned int protoff, |
Jozsef Kadlecsik | 5b1158e | 2006-12-02 22:07:13 -0800 | [diff] [blame] | 150 | unsigned int match_offset, |
| 151 | unsigned int match_len, |
| 152 | const char *rep_buffer, |
| 153 | unsigned int rep_len) |
| 154 | { |
Patrick McHardy | c7232c9 | 2012-08-26 19:14:06 +0200 | [diff] [blame] | 155 | const struct nf_nat_l3proto *l3proto; |
Jozsef Kadlecsik | 5b1158e | 2006-12-02 22:07:13 -0800 | [diff] [blame] | 156 | struct udphdr *udph; |
| 157 | int datalen, oldlen; |
| 158 | |
Herbert Xu | 3db05fe | 2007-10-15 00:53:15 -0700 | [diff] [blame] | 159 | if (!skb_make_writable(skb, skb->len)) |
Jozsef Kadlecsik | 5b1158e | 2006-12-02 22:07:13 -0800 | [diff] [blame] | 160 | return 0; |
| 161 | |
| 162 | if (rep_len > match_len && |
Herbert Xu | 3db05fe | 2007-10-15 00:53:15 -0700 | [diff] [blame] | 163 | rep_len - match_len > skb_tailroom(skb) && |
| 164 | !enlarge_skb(skb, rep_len - match_len)) |
Jozsef Kadlecsik | 5b1158e | 2006-12-02 22:07:13 -0800 | [diff] [blame] | 165 | return 0; |
| 166 | |
Patrick McHardy | c7232c9 | 2012-08-26 19:14:06 +0200 | [diff] [blame] | 167 | udph = (void *)skb->data + protoff; |
Jozsef Kadlecsik | 5b1158e | 2006-12-02 22:07:13 -0800 | [diff] [blame] | 168 | |
Patrick McHardy | c7232c9 | 2012-08-26 19:14:06 +0200 | [diff] [blame] | 169 | oldlen = skb->len - protoff; |
| 170 | mangle_contents(skb, protoff + sizeof(*udph), |
Jozsef Kadlecsik | 5b1158e | 2006-12-02 22:07:13 -0800 | [diff] [blame] | 171 | match_offset, match_len, rep_buffer, rep_len); |
| 172 | |
| 173 | /* update the length of the UDP packet */ |
Patrick McHardy | c7232c9 | 2012-08-26 19:14:06 +0200 | [diff] [blame] | 174 | datalen = skb->len - protoff; |
Jozsef Kadlecsik | 5b1158e | 2006-12-02 22:07:13 -0800 | [diff] [blame] | 175 | udph->len = htons(datalen); |
| 176 | |
| 177 | /* fix udp checksum if udp checksum was previously calculated */ |
Herbert Xu | 3db05fe | 2007-10-15 00:53:15 -0700 | [diff] [blame] | 178 | if (!udph->check && skb->ip_summed != CHECKSUM_PARTIAL) |
Jozsef Kadlecsik | 5b1158e | 2006-12-02 22:07:13 -0800 | [diff] [blame] | 179 | return 1; |
| 180 | |
Patrick McHardy | c7232c9 | 2012-08-26 19:14:06 +0200 | [diff] [blame] | 181 | l3proto = __nf_nat_l3proto_find(nf_ct_l3num(ct)); |
| 182 | l3proto->csum_recalc(skb, IPPROTO_UDP, udph, &udph->check, |
| 183 | datalen, oldlen); |
Jozsef Kadlecsik | 5b1158e | 2006-12-02 22:07:13 -0800 | [diff] [blame] | 184 | |
| 185 | return 1; |
| 186 | } |
| 187 | EXPORT_SYMBOL(nf_nat_mangle_udp_packet); |
| 188 | |
Jozsef Kadlecsik | 5b1158e | 2006-12-02 22:07:13 -0800 | [diff] [blame] | 189 | /* Setup NAT on this expected conntrack so it follows master. */ |
| 190 | /* If we fail to get a free NAT slot, we'll get dropped on confirm */ |
| 191 | void nf_nat_follow_master(struct nf_conn *ct, |
| 192 | struct nf_conntrack_expect *exp) |
| 193 | { |
Patrick McHardy | c7232c9 | 2012-08-26 19:14:06 +0200 | [diff] [blame] | 194 | struct nf_nat_range range; |
Jozsef Kadlecsik | 5b1158e | 2006-12-02 22:07:13 -0800 | [diff] [blame] | 195 | |
| 196 | /* This must be a fresh one. */ |
| 197 | BUG_ON(ct->status & IPS_NAT_DONE_MASK); |
| 198 | |
| 199 | /* Change src to where master sends to */ |
Patrick McHardy | cbc9f2f | 2011-12-23 13:59:49 +0100 | [diff] [blame] | 200 | range.flags = NF_NAT_RANGE_MAP_IPS; |
Patrick McHardy | c7232c9 | 2012-08-26 19:14:06 +0200 | [diff] [blame] | 201 | range.min_addr = range.max_addr |
| 202 | = ct->master->tuplehash[!exp->dir].tuple.dst.u3; |
Patrick McHardy | cbc9f2f | 2011-12-23 13:59:49 +0100 | [diff] [blame] | 203 | nf_nat_setup_info(ct, &range, NF_NAT_MANIP_SRC); |
Jozsef Kadlecsik | 5b1158e | 2006-12-02 22:07:13 -0800 | [diff] [blame] | 204 | |
| 205 | /* For DST manip, map port here to where it's expected. */ |
Patrick McHardy | cbc9f2f | 2011-12-23 13:59:49 +0100 | [diff] [blame] | 206 | range.flags = (NF_NAT_RANGE_MAP_IPS | NF_NAT_RANGE_PROTO_SPECIFIED); |
Patrick McHardy | c7232c9 | 2012-08-26 19:14:06 +0200 | [diff] [blame] | 207 | range.min_proto = range.max_proto = exp->saved_proto; |
| 208 | range.min_addr = range.max_addr |
| 209 | = ct->master->tuplehash[!exp->dir].tuple.src.u3; |
Patrick McHardy | cbc9f2f | 2011-12-23 13:59:49 +0100 | [diff] [blame] | 210 | nf_nat_setup_info(ct, &range, NF_NAT_MANIP_DST); |
Jozsef Kadlecsik | 5b1158e | 2006-12-02 22:07:13 -0800 | [diff] [blame] | 211 | } |
| 212 | EXPORT_SYMBOL(nf_nat_follow_master); |