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1/* Kernel module to match IPComp parameters for IPv4 and IPv6
2 *
3 * Copyright (C) 2013 WindRiver
4 *
5 * Author:
6 * Fan Du <fan.du@windriver.com>
7 *
8 * Based on:
9 * net/netfilter/xt_esp.c
10 *
11 * This program is free software; you can redistribute it and/or
12 * modify it under the terms of the GNU General Public License
13 * as published by the Free Software Foundation; either version
14 * 2 of the License, or (at your option) any later version.
15 */
16
17#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
18#include <linux/in.h>
19#include <linux/module.h>
20#include <linux/skbuff.h>
21#include <linux/ip.h>
22
23#include <linux/netfilter/xt_ipcomp.h>
24#include <linux/netfilter/x_tables.h>
25
26MODULE_LICENSE("GPL");
27MODULE_AUTHOR("Fan Du <fan.du@windriver.com>");
28MODULE_DESCRIPTION("Xtables: IPv4/6 IPsec-IPComp SPI match");
29MODULE_ALIAS("ipt_ipcomp");
30MODULE_ALIAS("ip6t_ipcomp");
31
32/* Returns 1 if the spi is matched by the range, 0 otherwise */
33static inline bool
34spi_match(u_int32_t min, u_int32_t max, u_int32_t spi, bool invert)
35{
36 bool r;
37 pr_debug("spi_match:%c 0x%x <= 0x%x <= 0x%x\n",
38 invert ? '!' : ' ', min, spi, max);
39 r = (spi >= min && spi <= max) ^ invert;
40 pr_debug(" result %s\n", r ? "PASS" : "FAILED");
41 return r;
42}
43
44static bool comp_mt(const struct sk_buff *skb, struct xt_action_param *par)
45{
46 struct ip_comp_hdr _comphdr;
47 const struct ip_comp_hdr *chdr;
48 const struct xt_ipcomp *compinfo = par->matchinfo;
49
50 /* Must not be a fragment. */
51 if (par->fragoff != 0)
52 return false;
53
54 chdr = skb_header_pointer(skb, par->thoff, sizeof(_comphdr), &_comphdr);
55 if (chdr == NULL) {
56 /* We've been asked to examine this packet, and we
57 * can't. Hence, no choice but to drop.
58 */
59 pr_debug("Dropping evil IPComp tinygram.\n");
60 par->hotdrop = true;
61 return 0;
62 }
63
64 return spi_match(compinfo->spis[0], compinfo->spis[1],
65 ntohs(chdr->cpi),
66 !!(compinfo->invflags & XT_IPCOMP_INV_SPI));
67}
68
69static int comp_mt_check(const struct xt_mtchk_param *par)
70{
71 const struct xt_ipcomp *compinfo = par->matchinfo;
72
73 /* Must specify no unknown invflags */
74 if (compinfo->invflags & ~XT_IPCOMP_INV_MASK) {
75 pr_err("unknown flags %X\n", compinfo->invflags);
76 return -EINVAL;
77 }
78 return 0;
79}
80
81static struct xt_match comp_mt_reg[] __read_mostly = {
82 {
83 .name = "ipcomp",
84 .family = NFPROTO_IPV4,
85 .match = comp_mt,
86 .matchsize = sizeof(struct xt_ipcomp),
87 .proto = IPPROTO_COMP,
88 .checkentry = comp_mt_check,
89 .me = THIS_MODULE,
90 },
91 {
92 .name = "ipcomp",
93 .family = NFPROTO_IPV6,
94 .match = comp_mt,
95 .matchsize = sizeof(struct xt_ipcomp),
96 .proto = IPPROTO_COMP,
97 .checkentry = comp_mt_check,
98 .me = THIS_MODULE,
99 },
100};
101
102static int __init comp_mt_init(void)
103{
104 return xt_register_matches(comp_mt_reg, ARRAY_SIZE(comp_mt_reg));
105}
106
107static void __exit comp_mt_exit(void)
108{
109 xt_unregister_matches(comp_mt_reg, ARRAY_SIZE(comp_mt_reg));
110}
111
112module_init(comp_mt_init);
113module_exit(comp_mt_exit);
1/* Kernel module to match IPComp parameters for IPv4 and IPv6
2 *
3 * Copyright (C) 2013 WindRiver
4 *
5 * Author:
6 * Fan Du <fan.du@windriver.com>
7 *
8 * Based on:
9 * net/netfilter/xt_esp.c
10 *
11 * This program is free software; you can redistribute it and/or
12 * modify it under the terms of the GNU General Public License
13 * as published by the Free Software Foundation; either version
14 * 2 of the License, or (at your option) any later version.
15 */
16
17#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
18#include <linux/in.h>
19#include <linux/module.h>
20#include <linux/skbuff.h>
21#include <linux/ip.h>
22
23#include <linux/netfilter/xt_ipcomp.h>
24#include <linux/netfilter/x_tables.h>
25
26MODULE_LICENSE("GPL");
27MODULE_AUTHOR("Fan Du <fan.du@windriver.com>");
28MODULE_DESCRIPTION("Xtables: IPv4/6 IPsec-IPComp SPI match");
29
30/* Returns 1 if the spi is matched by the range, 0 otherwise */
31static inline bool
32spi_match(u_int32_t min, u_int32_t max, u_int32_t spi, bool invert)
33{
34 bool r;
35 pr_debug("spi_match:%c 0x%x <= 0x%x <= 0x%x\n",
36 invert ? '!' : ' ', min, spi, max);
37 r = (spi >= min && spi <= max) ^ invert;
38 pr_debug(" result %s\n", r ? "PASS" : "FAILED");
39 return r;
40}
41
42static bool comp_mt(const struct sk_buff *skb, struct xt_action_param *par)
43{
44 struct ip_comp_hdr _comphdr;
45 const struct ip_comp_hdr *chdr;
46 const struct xt_ipcomp *compinfo = par->matchinfo;
47
48 /* Must not be a fragment. */
49 if (par->fragoff != 0)
50 return false;
51
52 chdr = skb_header_pointer(skb, par->thoff, sizeof(_comphdr), &_comphdr);
53 if (chdr == NULL) {
54 /* We've been asked to examine this packet, and we
55 * can't. Hence, no choice but to drop.
56 */
57 pr_debug("Dropping evil IPComp tinygram.\n");
58 par->hotdrop = true;
59 return 0;
60 }
61
62 return spi_match(compinfo->spis[0], compinfo->spis[1],
63 ntohs(chdr->cpi),
64 !!(compinfo->invflags & XT_IPCOMP_INV_SPI));
65}
66
67static int comp_mt_check(const struct xt_mtchk_param *par)
68{
69 const struct xt_ipcomp *compinfo = par->matchinfo;
70
71 /* Must specify no unknown invflags */
72 if (compinfo->invflags & ~XT_IPCOMP_INV_MASK) {
73 pr_err("unknown flags %X\n", compinfo->invflags);
74 return -EINVAL;
75 }
76 return 0;
77}
78
79static struct xt_match comp_mt_reg[] __read_mostly = {
80 {
81 .name = "ipcomp",
82 .family = NFPROTO_IPV4,
83 .match = comp_mt,
84 .matchsize = sizeof(struct xt_ipcomp),
85 .proto = IPPROTO_COMP,
86 .checkentry = comp_mt_check,
87 .me = THIS_MODULE,
88 },
89 {
90 .name = "ipcomp",
91 .family = NFPROTO_IPV6,
92 .match = comp_mt,
93 .matchsize = sizeof(struct xt_ipcomp),
94 .proto = IPPROTO_COMP,
95 .checkentry = comp_mt_check,
96 .me = THIS_MODULE,
97 },
98};
99
100static int __init comp_mt_init(void)
101{
102 return xt_register_matches(comp_mt_reg, ARRAY_SIZE(comp_mt_reg));
103}
104
105static void __exit comp_mt_exit(void)
106{
107 xt_unregister_matches(comp_mt_reg, ARRAY_SIZE(comp_mt_reg));
108}
109
110module_init(comp_mt_init);
111module_exit(comp_mt_exit);