netfilter: nf_log: fix sleeping function called from invalid context
[linux-2.6.git] / net / netfilter / xt_tcpmss.c
1 /* Kernel module to match TCP MSS values. */
2
3 /* Copyright (C) 2000 Marc Boucher <marc@mbsi.ca>
4  * Portions (C) 2005 by Harald Welte <laforge@netfilter.org>
5  *
6  * This program is free software; you can redistribute it and/or modify
7  * it under the terms of the GNU General Public License version 2 as
8  * published by the Free Software Foundation.
9  */
10
11 #include <linux/module.h>
12 #include <linux/skbuff.h>
13 #include <net/tcp.h>
14
15 #include <linux/netfilter/xt_tcpmss.h>
16 #include <linux/netfilter/x_tables.h>
17
18 #include <linux/netfilter_ipv4/ip_tables.h>
19 #include <linux/netfilter_ipv6/ip6_tables.h>
20
21 MODULE_LICENSE("GPL");
22 MODULE_AUTHOR("Marc Boucher <marc@mbsi.ca>");
23 MODULE_DESCRIPTION("Xtables: TCP MSS match");
24 MODULE_ALIAS("ipt_tcpmss");
25 MODULE_ALIAS("ip6t_tcpmss");
26
27 static bool
28 tcpmss_mt(const struct sk_buff *skb, const struct xt_match_param *par)
29 {
30         const struct xt_tcpmss_match_info *info = par->matchinfo;
31         const struct tcphdr *th;
32         struct tcphdr _tcph;
33         /* tcp.doff is only 4 bits, ie. max 15 * 4 bytes */
34         const u_int8_t *op;
35         u8 _opt[15 * 4 - sizeof(_tcph)];
36         unsigned int i, optlen;
37
38         /* If we don't have the whole header, drop packet. */
39         th = skb_header_pointer(skb, par->thoff, sizeof(_tcph), &_tcph);
40         if (th == NULL)
41                 goto dropit;
42
43         /* Malformed. */
44         if (th->doff*4 < sizeof(*th))
45                 goto dropit;
46
47         optlen = th->doff*4 - sizeof(*th);
48         if (!optlen)
49                 goto out;
50
51         /* Truncated options. */
52         op = skb_header_pointer(skb, par->thoff + sizeof(*th), optlen, _opt);
53         if (op == NULL)
54                 goto dropit;
55
56         for (i = 0; i < optlen; ) {
57                 if (op[i] == TCPOPT_MSS
58                     && (optlen - i) >= TCPOLEN_MSS
59                     && op[i+1] == TCPOLEN_MSS) {
60                         u_int16_t mssval;
61
62                         mssval = (op[i+2] << 8) | op[i+3];
63
64                         return (mssval >= info->mss_min &&
65                                 mssval <= info->mss_max) ^ info->invert;
66                 }
67                 if (op[i] < 2)
68                         i++;
69                 else
70                         i += op[i+1] ? : 1;
71         }
72 out:
73         return info->invert;
74
75 dropit:
76         *par->hotdrop = true;
77         return false;
78 }
79
80 static struct xt_match tcpmss_mt_reg[] __read_mostly = {
81         {
82                 .name           = "tcpmss",
83                 .family         = NFPROTO_IPV4,
84                 .match          = tcpmss_mt,
85                 .matchsize      = sizeof(struct xt_tcpmss_match_info),
86                 .proto          = IPPROTO_TCP,
87                 .me             = THIS_MODULE,
88         },
89         {
90                 .name           = "tcpmss",
91                 .family         = NFPROTO_IPV6,
92                 .match          = tcpmss_mt,
93                 .matchsize      = sizeof(struct xt_tcpmss_match_info),
94                 .proto          = IPPROTO_TCP,
95                 .me             = THIS_MODULE,
96         },
97 };
98
99 static int __init tcpmss_mt_init(void)
100 {
101         return xt_register_matches(tcpmss_mt_reg, ARRAY_SIZE(tcpmss_mt_reg));
102 }
103
104 static void __exit tcpmss_mt_exit(void)
105 {
106         xt_unregister_matches(tcpmss_mt_reg, ARRAY_SIZE(tcpmss_mt_reg));
107 }
108
109 module_init(tcpmss_mt_init);
110 module_exit(tcpmss_mt_exit);