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41d73ec0 PM |
1 | #include <linux/types.h> |
2 | #include <linux/netfilter.h> | |
3 | #include <net/tcp.h> | |
4 | ||
5 | #include <net/netfilter/nf_conntrack.h> | |
6 | #include <net/netfilter/nf_conntrack_extend.h> | |
7 | #include <net/netfilter/nf_conntrack_seqadj.h> | |
8 | ||
48b1de4c PM |
9 | int nf_ct_seqadj_init(struct nf_conn *ct, enum ip_conntrack_info ctinfo, |
10 | s32 off) | |
11 | { | |
12 | enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo); | |
13 | struct nf_conn_seqadj *seqadj; | |
14 | struct nf_ct_seqadj *this_way; | |
15 | ||
16 | if (off == 0) | |
17 | return 0; | |
18 | ||
19 | set_bit(IPS_SEQ_ADJUST_BIT, &ct->status); | |
20 | ||
21 | seqadj = nfct_seqadj(ct); | |
22 | this_way = &seqadj->seq[dir]; | |
23 | this_way->offset_before = off; | |
24 | this_way->offset_after = off; | |
25 | return 0; | |
26 | } | |
27 | EXPORT_SYMBOL_GPL(nf_ct_seqadj_init); | |
28 | ||
41d73ec0 PM |
29 | int nf_ct_seqadj_set(struct nf_conn *ct, enum ip_conntrack_info ctinfo, |
30 | __be32 seq, s32 off) | |
31 | { | |
32 | struct nf_conn_seqadj *seqadj = nfct_seqadj(ct); | |
33 | enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo); | |
34 | struct nf_ct_seqadj *this_way; | |
35 | ||
36 | if (off == 0) | |
37 | return 0; | |
38 | ||
39 | set_bit(IPS_SEQ_ADJUST_BIT, &ct->status); | |
40 | ||
41 | spin_lock_bh(&ct->lock); | |
42 | this_way = &seqadj->seq[dir]; | |
43 | if (this_way->offset_before == this_way->offset_after || | |
44 | before(this_way->correction_pos, seq)) { | |
45 | this_way->correction_pos = seq; | |
46 | this_way->offset_before = this_way->offset_after; | |
47 | this_way->offset_after += off; | |
48 | } | |
49 | spin_unlock_bh(&ct->lock); | |
50 | return 0; | |
51 | } | |
52 | EXPORT_SYMBOL_GPL(nf_ct_seqadj_set); | |
53 | ||
54 | void nf_ct_tcp_seqadj_set(struct sk_buff *skb, | |
55 | struct nf_conn *ct, enum ip_conntrack_info ctinfo, | |
56 | s32 off) | |
57 | { | |
58 | const struct tcphdr *th; | |
59 | ||
60 | if (nf_ct_protonum(ct) != IPPROTO_TCP) | |
61 | return; | |
62 | ||
63 | th = (struct tcphdr *)(skb_network_header(skb) + ip_hdrlen(skb)); | |
64 | nf_ct_seqadj_set(ct, ctinfo, th->seq, off); | |
65 | } | |
66 | EXPORT_SYMBOL_GPL(nf_ct_tcp_seqadj_set); | |
67 | ||
68 | /* Adjust one found SACK option including checksum correction */ | |
69 | static void nf_ct_sack_block_adjust(struct sk_buff *skb, | |
70 | struct tcphdr *tcph, | |
71 | unsigned int sackoff, | |
72 | unsigned int sackend, | |
73 | struct nf_ct_seqadj *seq) | |
74 | { | |
75 | while (sackoff < sackend) { | |
76 | struct tcp_sack_block_wire *sack; | |
77 | __be32 new_start_seq, new_end_seq; | |
78 | ||
79 | sack = (void *)skb->data + sackoff; | |
80 | if (after(ntohl(sack->start_seq) - seq->offset_before, | |
81 | seq->correction_pos)) | |
82 | new_start_seq = htonl(ntohl(sack->start_seq) - | |
83 | seq->offset_after); | |
84 | else | |
85 | new_start_seq = htonl(ntohl(sack->start_seq) - | |
86 | seq->offset_before); | |
87 | ||
88 | if (after(ntohl(sack->end_seq) - seq->offset_before, | |
89 | seq->correction_pos)) | |
90 | new_end_seq = htonl(ntohl(sack->end_seq) - | |
91 | seq->offset_after); | |
92 | else | |
93 | new_end_seq = htonl(ntohl(sack->end_seq) - | |
94 | seq->offset_before); | |
95 | ||
96 | pr_debug("sack_adjust: start_seq: %d->%d, end_seq: %d->%d\n", | |
97 | ntohl(sack->start_seq), new_start_seq, | |
98 | ntohl(sack->end_seq), new_end_seq); | |
99 | ||
100 | inet_proto_csum_replace4(&tcph->check, skb, | |
101 | sack->start_seq, new_start_seq, 0); | |
102 | inet_proto_csum_replace4(&tcph->check, skb, | |
103 | sack->end_seq, new_end_seq, 0); | |
104 | sack->start_seq = new_start_seq; | |
105 | sack->end_seq = new_end_seq; | |
106 | sackoff += sizeof(*sack); | |
107 | } | |
108 | } | |
109 | ||
110 | /* TCP SACK sequence number adjustment */ | |
111 | static unsigned int nf_ct_sack_adjust(struct sk_buff *skb, | |
112 | unsigned int protoff, | |
113 | struct tcphdr *tcph, | |
114 | struct nf_conn *ct, | |
115 | enum ip_conntrack_info ctinfo) | |
116 | { | |
117 | unsigned int dir, optoff, optend; | |
118 | struct nf_conn_seqadj *seqadj = nfct_seqadj(ct); | |
119 | ||
120 | optoff = protoff + sizeof(struct tcphdr); | |
121 | optend = protoff + tcph->doff * 4; | |
122 | ||
123 | if (!skb_make_writable(skb, optend)) | |
124 | return 0; | |
125 | ||
126 | dir = CTINFO2DIR(ctinfo); | |
127 | ||
128 | while (optoff < optend) { | |
129 | /* Usually: option, length. */ | |
130 | unsigned char *op = skb->data + optoff; | |
131 | ||
132 | switch (op[0]) { | |
133 | case TCPOPT_EOL: | |
134 | return 1; | |
135 | case TCPOPT_NOP: | |
136 | optoff++; | |
137 | continue; | |
138 | default: | |
139 | /* no partial options */ | |
140 | if (optoff + 1 == optend || | |
141 | optoff + op[1] > optend || | |
142 | op[1] < 2) | |
143 | return 0; | |
144 | if (op[0] == TCPOPT_SACK && | |
145 | op[1] >= 2+TCPOLEN_SACK_PERBLOCK && | |
146 | ((op[1] - 2) % TCPOLEN_SACK_PERBLOCK) == 0) | |
147 | nf_ct_sack_block_adjust(skb, tcph, optoff + 2, | |
148 | optoff+op[1], | |
149 | &seqadj->seq[!dir]); | |
150 | optoff += op[1]; | |
151 | } | |
152 | } | |
153 | return 1; | |
154 | } | |
155 | ||
156 | /* TCP sequence number adjustment. Returns 1 on success, 0 on failure */ | |
157 | int nf_ct_seq_adjust(struct sk_buff *skb, | |
158 | struct nf_conn *ct, enum ip_conntrack_info ctinfo, | |
159 | unsigned int protoff) | |
160 | { | |
161 | enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo); | |
162 | struct tcphdr *tcph; | |
163 | __be32 newseq, newack; | |
164 | s32 seqoff, ackoff; | |
165 | struct nf_conn_seqadj *seqadj = nfct_seqadj(ct); | |
166 | struct nf_ct_seqadj *this_way, *other_way; | |
167 | int res; | |
168 | ||
169 | this_way = &seqadj->seq[dir]; | |
170 | other_way = &seqadj->seq[!dir]; | |
171 | ||
172 | if (!skb_make_writable(skb, protoff + sizeof(*tcph))) | |
173 | return 0; | |
174 | ||
175 | tcph = (void *)skb->data + protoff; | |
176 | spin_lock_bh(&ct->lock); | |
177 | if (after(ntohl(tcph->seq), this_way->correction_pos)) | |
178 | seqoff = this_way->offset_after; | |
179 | else | |
180 | seqoff = this_way->offset_before; | |
181 | ||
182 | if (after(ntohl(tcph->ack_seq) - other_way->offset_before, | |
183 | other_way->correction_pos)) | |
184 | ackoff = other_way->offset_after; | |
185 | else | |
186 | ackoff = other_way->offset_before; | |
187 | ||
188 | newseq = htonl(ntohl(tcph->seq) + seqoff); | |
189 | newack = htonl(ntohl(tcph->ack_seq) - ackoff); | |
190 | ||
191 | inet_proto_csum_replace4(&tcph->check, skb, tcph->seq, newseq, 0); | |
192 | inet_proto_csum_replace4(&tcph->check, skb, tcph->ack_seq, newack, 0); | |
193 | ||
194 | pr_debug("Adjusting sequence number from %u->%u, ack from %u->%u\n", | |
195 | ntohl(tcph->seq), ntohl(newseq), ntohl(tcph->ack_seq), | |
196 | ntohl(newack)); | |
197 | ||
198 | tcph->seq = newseq; | |
199 | tcph->ack_seq = newack; | |
200 | ||
201 | res = nf_ct_sack_adjust(skb, protoff, tcph, ct, ctinfo); | |
202 | spin_unlock_bh(&ct->lock); | |
203 | ||
204 | return res; | |
205 | } | |
206 | EXPORT_SYMBOL_GPL(nf_ct_seq_adjust); | |
207 | ||
208 | s32 nf_ct_seq_offset(const struct nf_conn *ct, | |
209 | enum ip_conntrack_dir dir, | |
210 | u32 seq) | |
211 | { | |
212 | struct nf_conn_seqadj *seqadj = nfct_seqadj(ct); | |
213 | struct nf_ct_seqadj *this_way; | |
214 | ||
215 | if (!seqadj) | |
216 | return 0; | |
217 | ||
218 | this_way = &seqadj->seq[dir]; | |
219 | return after(seq, this_way->correction_pos) ? | |
220 | this_way->offset_after : this_way->offset_before; | |
221 | } | |
222 | EXPORT_SYMBOL_GPL(nf_ct_seq_offset); | |
223 | ||
224 | static struct nf_ct_ext_type nf_ct_seqadj_extend __read_mostly = { | |
225 | .len = sizeof(struct nf_conn_seqadj), | |
226 | .align = __alignof__(struct nf_conn_seqadj), | |
227 | .id = NF_CT_EXT_SEQADJ, | |
228 | }; | |
229 | ||
230 | int nf_conntrack_seqadj_init(void) | |
231 | { | |
232 | return nf_ct_extend_register(&nf_ct_seqadj_extend); | |
233 | } | |
234 | ||
235 | void nf_conntrack_seqadj_fini(void) | |
236 | { | |
237 | nf_ct_extend_unregister(&nf_ct_seqadj_extend); | |
238 | } |