1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* Kernel module to match ESP parameters. */ |
3 | |
4 | /* (C) 1999-2000 Yon Uriarte <yon@astaro.de> |
5 | */ |
6 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
7 | #include <linux/module.h> |
8 | #include <linux/skbuff.h> |
9 | #include <linux/in.h> |
10 | #include <linux/ip.h> |
11 | |
12 | #include <linux/netfilter/xt_esp.h> |
13 | #include <linux/netfilter/x_tables.h> |
14 | |
15 | #include <linux/netfilter_ipv4/ip_tables.h> |
16 | #include <linux/netfilter_ipv6/ip6_tables.h> |
17 | |
18 | MODULE_LICENSE("GPL" ); |
19 | MODULE_AUTHOR("Yon Uriarte <yon@astaro.de>" ); |
20 | MODULE_DESCRIPTION("Xtables: IPsec-ESP packet match" ); |
21 | MODULE_ALIAS("ipt_esp" ); |
22 | MODULE_ALIAS("ip6t_esp" ); |
23 | |
24 | /* Returns 1 if the spi is matched by the range, 0 otherwise */ |
25 | static inline bool |
26 | spi_match(u_int32_t min, u_int32_t max, u_int32_t spi, bool invert) |
27 | { |
28 | bool r; |
29 | pr_debug("spi_match:%c 0x%x <= 0x%x <= 0x%x\n" , |
30 | invert ? '!' : ' ', min, spi, max); |
31 | r = (spi >= min && spi <= max) ^ invert; |
32 | pr_debug(" result %s\n" , r ? "PASS" : "FAILED" ); |
33 | return r; |
34 | } |
35 | |
36 | static bool esp_mt(const struct sk_buff *skb, struct xt_action_param *par) |
37 | { |
38 | const struct ip_esp_hdr *eh; |
39 | struct ip_esp_hdr _esp; |
40 | const struct xt_esp *espinfo = par->matchinfo; |
41 | |
42 | /* Must not be a fragment. */ |
43 | if (par->fragoff != 0) |
44 | return false; |
45 | |
46 | eh = skb_header_pointer(skb, offset: par->thoff, len: sizeof(_esp), buffer: &_esp); |
47 | if (eh == NULL) { |
48 | /* We've been asked to examine this packet, and we |
49 | * can't. Hence, no choice but to drop. |
50 | */ |
51 | pr_debug("Dropping evil ESP tinygram.\n" ); |
52 | par->hotdrop = true; |
53 | return false; |
54 | } |
55 | |
56 | return spi_match(min: espinfo->spis[0], max: espinfo->spis[1], ntohl(eh->spi), |
57 | invert: !!(espinfo->invflags & XT_ESP_INV_SPI)); |
58 | } |
59 | |
60 | static int esp_mt_check(const struct xt_mtchk_param *par) |
61 | { |
62 | const struct xt_esp *espinfo = par->matchinfo; |
63 | |
64 | if (espinfo->invflags & ~XT_ESP_INV_MASK) { |
65 | pr_debug("unknown flags %X\n" , espinfo->invflags); |
66 | return -EINVAL; |
67 | } |
68 | |
69 | return 0; |
70 | } |
71 | |
72 | static struct xt_match esp_mt_reg[] __read_mostly = { |
73 | { |
74 | .name = "esp" , |
75 | .family = NFPROTO_IPV4, |
76 | .checkentry = esp_mt_check, |
77 | .match = esp_mt, |
78 | .matchsize = sizeof(struct xt_esp), |
79 | .proto = IPPROTO_ESP, |
80 | .me = THIS_MODULE, |
81 | }, |
82 | { |
83 | .name = "esp" , |
84 | .family = NFPROTO_IPV6, |
85 | .checkentry = esp_mt_check, |
86 | .match = esp_mt, |
87 | .matchsize = sizeof(struct xt_esp), |
88 | .proto = IPPROTO_ESP, |
89 | .me = THIS_MODULE, |
90 | }, |
91 | }; |
92 | |
93 | static int __init esp_mt_init(void) |
94 | { |
95 | return xt_register_matches(match: esp_mt_reg, ARRAY_SIZE(esp_mt_reg)); |
96 | } |
97 | |
98 | static void __exit esp_mt_exit(void) |
99 | { |
100 | xt_unregister_matches(match: esp_mt_reg, ARRAY_SIZE(esp_mt_reg)); |
101 | } |
102 | |
103 | module_init(esp_mt_init); |
104 | module_exit(esp_mt_exit); |
105 | |