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