1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* Kernel module to match IPComp parameters for IPv4 and IPv6
3 *
4 * Copyright (C) 2013 WindRiver
5 *
6 * Author:
7 * Fan Du <fan.du@windriver.com>
8 *
9 * Based on:
10 * net/netfilter/xt_esp.c
11 */
12
13 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
14 #include <linux/in.h>
15 #include <linux/module.h>
16 #include <linux/skbuff.h>
17 #include <linux/ip.h>
18
19 #include <linux/netfilter/xt_ipcomp.h>
20 #include <linux/netfilter/x_tables.h>
21
22 MODULE_LICENSE("GPL");
23 MODULE_AUTHOR("Fan Du <fan.du@windriver.com>");
24 MODULE_DESCRIPTION("Xtables: IPv4/6 IPsec-IPComp SPI match");
25 MODULE_ALIAS("ipt_ipcomp");
26 MODULE_ALIAS("ip6t_ipcomp");
27
28 /* Returns 1 if the spi is matched by the range, 0 otherwise */
29 static inline bool
spi_match(u_int32_t min,u_int32_t max,u_int32_t spi,bool invert)30 spi_match(u_int32_t min, u_int32_t max, u_int32_t spi, bool invert)
31 {
32 bool r;
33 pr_debug("spi_match:%c 0x%x <= 0x%x <= 0x%x\n",
34 invert ? '!' : ' ', min, spi, max);
35 r = (spi >= min && spi <= max) ^ invert;
36 pr_debug(" result %s\n", r ? "PASS" : "FAILED");
37 return r;
38 }
39
comp_mt(const struct sk_buff * skb,struct xt_action_param * par)40 static bool comp_mt(const struct sk_buff *skb, struct xt_action_param *par)
41 {
42 struct ip_comp_hdr _comphdr;
43 const struct ip_comp_hdr *chdr;
44 const struct xt_ipcomp *compinfo = par->matchinfo;
45
46 /* Must not be a fragment. */
47 if (par->fragoff != 0)
48 return false;
49
50 chdr = skb_header_pointer(skb, par->thoff, sizeof(_comphdr), &_comphdr);
51 if (chdr == NULL) {
52 /* We've been asked to examine this packet, and we
53 * can't. Hence, no choice but to drop.
54 */
55 pr_debug("Dropping evil IPComp tinygram.\n");
56 par->hotdrop = true;
57 return false;
58 }
59
60 return spi_match(compinfo->spis[0], compinfo->spis[1],
61 ntohs(chdr->cpi),
62 !!(compinfo->invflags & XT_IPCOMP_INV_SPI));
63 }
64
comp_mt_check(const struct xt_mtchk_param * par)65 static int comp_mt_check(const struct xt_mtchk_param *par)
66 {
67 const struct xt_ipcomp *compinfo = par->matchinfo;
68
69 /* Must specify no unknown invflags */
70 if (compinfo->invflags & ~XT_IPCOMP_INV_MASK) {
71 pr_info_ratelimited("unknown flags %X\n", compinfo->invflags);
72 return -EINVAL;
73 }
74 return 0;
75 }
76
77 static struct xt_match comp_mt_reg[] __read_mostly = {
78 {
79 .name = "ipcomp",
80 .family = NFPROTO_IPV4,
81 .match = comp_mt,
82 .matchsize = sizeof(struct xt_ipcomp),
83 .proto = IPPROTO_COMP,
84 .checkentry = comp_mt_check,
85 .me = THIS_MODULE,
86 },
87 {
88 .name = "ipcomp",
89 .family = NFPROTO_IPV6,
90 .match = comp_mt,
91 .matchsize = sizeof(struct xt_ipcomp),
92 .proto = IPPROTO_COMP,
93 .checkentry = comp_mt_check,
94 .me = THIS_MODULE,
95 },
96 };
97
comp_mt_init(void)98 static int __init comp_mt_init(void)
99 {
100 return xt_register_matches(comp_mt_reg, ARRAY_SIZE(comp_mt_reg));
101 }
102
comp_mt_exit(void)103 static void __exit comp_mt_exit(void)
104 {
105 xt_unregister_matches(comp_mt_reg, ARRAY_SIZE(comp_mt_reg));
106 }
107
108 module_init(comp_mt_init);
109 module_exit(comp_mt_exit);
110
