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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 | ||
db12cf27 | 39 | if (unlikely(!seqadj)) { |
f2661adc | 40 | WARN_ONCE(1, "Missing nfct_seqadj_ext_add() setup call\n"); |
db12cf27 JDB |
41 | return 0; |
42 | } | |
43 | ||
41d73ec0 PM |
44 | set_bit(IPS_SEQ_ADJUST_BIT, &ct->status); |
45 | ||
46 | spin_lock_bh(&ct->lock); | |
47 | this_way = &seqadj->seq[dir]; | |
48 | if (this_way->offset_before == this_way->offset_after || | |
23dfe136 PO |
49 | before(this_way->correction_pos, ntohl(seq))) { |
50 | this_way->correction_pos = ntohl(seq); | |
41d73ec0 PM |
51 | this_way->offset_before = this_way->offset_after; |
52 | this_way->offset_after += off; | |
53 | } | |
54 | spin_unlock_bh(&ct->lock); | |
55 | return 0; | |
56 | } | |
57 | EXPORT_SYMBOL_GPL(nf_ct_seqadj_set); | |
58 | ||
59 | void nf_ct_tcp_seqadj_set(struct sk_buff *skb, | |
60 | struct nf_conn *ct, enum ip_conntrack_info ctinfo, | |
61 | s32 off) | |
62 | { | |
63 | const struct tcphdr *th; | |
64 | ||
65 | if (nf_ct_protonum(ct) != IPPROTO_TCP) | |
66 | return; | |
67 | ||
68 | th = (struct tcphdr *)(skb_network_header(skb) + ip_hdrlen(skb)); | |
69 | nf_ct_seqadj_set(ct, ctinfo, th->seq, off); | |
70 | } | |
71 | EXPORT_SYMBOL_GPL(nf_ct_tcp_seqadj_set); | |
72 | ||
73 | /* Adjust one found SACK option including checksum correction */ | |
74 | static void nf_ct_sack_block_adjust(struct sk_buff *skb, | |
75 | struct tcphdr *tcph, | |
76 | unsigned int sackoff, | |
77 | unsigned int sackend, | |
78 | struct nf_ct_seqadj *seq) | |
79 | { | |
80 | while (sackoff < sackend) { | |
81 | struct tcp_sack_block_wire *sack; | |
82 | __be32 new_start_seq, new_end_seq; | |
83 | ||
84 | sack = (void *)skb->data + sackoff; | |
85 | if (after(ntohl(sack->start_seq) - seq->offset_before, | |
86 | seq->correction_pos)) | |
87 | new_start_seq = htonl(ntohl(sack->start_seq) - | |
88 | seq->offset_after); | |
89 | else | |
90 | new_start_seq = htonl(ntohl(sack->start_seq) - | |
91 | seq->offset_before); | |
92 | ||
93 | if (after(ntohl(sack->end_seq) - seq->offset_before, | |
94 | seq->correction_pos)) | |
95 | new_end_seq = htonl(ntohl(sack->end_seq) - | |
96 | seq->offset_after); | |
97 | else | |
98 | new_end_seq = htonl(ntohl(sack->end_seq) - | |
99 | seq->offset_before); | |
100 | ||
b44b565c G |
101 | pr_debug("sack_adjust: start_seq: %u->%u, end_seq: %u->%u\n", |
102 | ntohl(sack->start_seq), ntohl(new_start_seq), | |
103 | ntohl(sack->end_seq), ntohl(new_end_seq)); | |
41d73ec0 PM |
104 | |
105 | inet_proto_csum_replace4(&tcph->check, skb, | |
4b048d6d | 106 | sack->start_seq, new_start_seq, false); |
41d73ec0 | 107 | inet_proto_csum_replace4(&tcph->check, skb, |
4b048d6d | 108 | sack->end_seq, new_end_seq, false); |
41d73ec0 PM |
109 | sack->start_seq = new_start_seq; |
110 | sack->end_seq = new_end_seq; | |
111 | sackoff += sizeof(*sack); | |
112 | } | |
113 | } | |
114 | ||
115 | /* TCP SACK sequence number adjustment */ | |
116 | static unsigned int nf_ct_sack_adjust(struct sk_buff *skb, | |
117 | unsigned int protoff, | |
118 | struct tcphdr *tcph, | |
119 | struct nf_conn *ct, | |
120 | enum ip_conntrack_info ctinfo) | |
121 | { | |
122 | unsigned int dir, optoff, optend; | |
123 | struct nf_conn_seqadj *seqadj = nfct_seqadj(ct); | |
124 | ||
125 | optoff = protoff + sizeof(struct tcphdr); | |
126 | optend = protoff + tcph->doff * 4; | |
127 | ||
128 | if (!skb_make_writable(skb, optend)) | |
129 | return 0; | |
130 | ||
131 | dir = CTINFO2DIR(ctinfo); | |
132 | ||
133 | while (optoff < optend) { | |
134 | /* Usually: option, length. */ | |
135 | unsigned char *op = skb->data + optoff; | |
136 | ||
137 | switch (op[0]) { | |
138 | case TCPOPT_EOL: | |
139 | return 1; | |
140 | case TCPOPT_NOP: | |
141 | optoff++; | |
142 | continue; | |
143 | default: | |
144 | /* no partial options */ | |
145 | if (optoff + 1 == optend || | |
146 | optoff + op[1] > optend || | |
147 | op[1] < 2) | |
148 | return 0; | |
149 | if (op[0] == TCPOPT_SACK && | |
150 | op[1] >= 2+TCPOLEN_SACK_PERBLOCK && | |
151 | ((op[1] - 2) % TCPOLEN_SACK_PERBLOCK) == 0) | |
152 | nf_ct_sack_block_adjust(skb, tcph, optoff + 2, | |
153 | optoff+op[1], | |
154 | &seqadj->seq[!dir]); | |
155 | optoff += op[1]; | |
156 | } | |
157 | } | |
158 | return 1; | |
159 | } | |
160 | ||
161 | /* TCP sequence number adjustment. Returns 1 on success, 0 on failure */ | |
162 | int nf_ct_seq_adjust(struct sk_buff *skb, | |
163 | struct nf_conn *ct, enum ip_conntrack_info ctinfo, | |
164 | unsigned int protoff) | |
165 | { | |
166 | enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo); | |
167 | struct tcphdr *tcph; | |
168 | __be32 newseq, newack; | |
169 | s32 seqoff, ackoff; | |
170 | struct nf_conn_seqadj *seqadj = nfct_seqadj(ct); | |
171 | struct nf_ct_seqadj *this_way, *other_way; | |
8d11350f | 172 | int res = 1; |
41d73ec0 PM |
173 | |
174 | this_way = &seqadj->seq[dir]; | |
175 | other_way = &seqadj->seq[!dir]; | |
176 | ||
177 | if (!skb_make_writable(skb, protoff + sizeof(*tcph))) | |
178 | return 0; | |
179 | ||
180 | tcph = (void *)skb->data + protoff; | |
181 | spin_lock_bh(&ct->lock); | |
182 | if (after(ntohl(tcph->seq), this_way->correction_pos)) | |
183 | seqoff = this_way->offset_after; | |
184 | else | |
185 | seqoff = this_way->offset_before; | |
186 | ||
8d11350f GF |
187 | newseq = htonl(ntohl(tcph->seq) + seqoff); |
188 | inet_proto_csum_replace4(&tcph->check, skb, tcph->seq, newseq, false); | |
189 | pr_debug("Adjusting sequence number from %u->%u\n", | |
190 | ntohl(tcph->seq), ntohl(newseq)); | |
191 | tcph->seq = newseq; | |
192 | ||
193 | if (!tcph->ack) | |
194 | goto out; | |
195 | ||
41d73ec0 PM |
196 | if (after(ntohl(tcph->ack_seq) - other_way->offset_before, |
197 | other_way->correction_pos)) | |
198 | ackoff = other_way->offset_after; | |
199 | else | |
200 | ackoff = other_way->offset_before; | |
201 | ||
41d73ec0 | 202 | newack = htonl(ntohl(tcph->ack_seq) - ackoff); |
4b048d6d TH |
203 | inet_proto_csum_replace4(&tcph->check, skb, tcph->ack_seq, newack, |
204 | false); | |
8d11350f | 205 | pr_debug("Adjusting ack number from %u->%u, ack from %u->%u\n", |
41d73ec0 PM |
206 | ntohl(tcph->seq), ntohl(newseq), ntohl(tcph->ack_seq), |
207 | ntohl(newack)); | |
41d73ec0 PM |
208 | tcph->ack_seq = newack; |
209 | ||
210 | res = nf_ct_sack_adjust(skb, protoff, tcph, ct, ctinfo); | |
8d11350f | 211 | out: |
41d73ec0 PM |
212 | spin_unlock_bh(&ct->lock); |
213 | ||
214 | return res; | |
215 | } | |
216 | EXPORT_SYMBOL_GPL(nf_ct_seq_adjust); | |
217 | ||
218 | s32 nf_ct_seq_offset(const struct nf_conn *ct, | |
219 | enum ip_conntrack_dir dir, | |
220 | u32 seq) | |
221 | { | |
222 | struct nf_conn_seqadj *seqadj = nfct_seqadj(ct); | |
223 | struct nf_ct_seqadj *this_way; | |
224 | ||
225 | if (!seqadj) | |
226 | return 0; | |
227 | ||
228 | this_way = &seqadj->seq[dir]; | |
229 | return after(seq, this_way->correction_pos) ? | |
230 | this_way->offset_after : this_way->offset_before; | |
231 | } | |
232 | EXPORT_SYMBOL_GPL(nf_ct_seq_offset); | |
233 | ||
23f671a1 | 234 | static const struct nf_ct_ext_type nf_ct_seqadj_extend = { |
41d73ec0 PM |
235 | .len = sizeof(struct nf_conn_seqadj), |
236 | .align = __alignof__(struct nf_conn_seqadj), | |
237 | .id = NF_CT_EXT_SEQADJ, | |
238 | }; | |
239 | ||
240 | int nf_conntrack_seqadj_init(void) | |
241 | { | |
242 | return nf_ct_extend_register(&nf_ct_seqadj_extend); | |
243 | } | |
244 | ||
245 | void nf_conntrack_seqadj_fini(void) | |
246 | { | |
247 | nf_ct_extend_unregister(&nf_ct_seqadj_extend); | |
248 | } |