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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
18MODULE_LICENSE("GPL");
19MODULE_AUTHOR("Yon Uriarte <yon@astaro.de>");
20MODULE_DESCRIPTION("Xtables: IPsec-ESP packet match");
21MODULE_ALIAS("ipt_esp");
22MODULE_ALIAS("ip6t_esp");
23
24/* Returns 1 if the spi is matched by the range, 0 otherwise */
25static inline bool
26spi_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
36static 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, par->thoff, sizeof(_esp), &_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(espinfo->spis[0], espinfo->spis[1], ntohl(eh->spi),
57 !!(espinfo->invflags & XT_ESP_INV_SPI));
58}
59
60static 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
72static 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
93static int __init esp_mt_init(void)
94{
95 return xt_register_matches(esp_mt_reg, ARRAY_SIZE(esp_mt_reg));
96}
97
98static void __exit esp_mt_exit(void)
99{
100 xt_unregister_matches(esp_mt_reg, ARRAY_SIZE(esp_mt_reg));
101}
102
103module_init(esp_mt_init);
104module_exit(esp_mt_exit);
1/* Kernel module to match ESP parameters. */
2
3/* (C) 1999-2000 Yon Uriarte <yon@astaro.de>
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License version 2 as
7 * published by the Free Software Foundation.
8 */
9#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
10#include <linux/module.h>
11#include <linux/skbuff.h>
12#include <linux/in.h>
13#include <linux/ip.h>
14
15#include <linux/netfilter/xt_esp.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
21MODULE_LICENSE("GPL");
22MODULE_AUTHOR("Yon Uriarte <yon@astaro.de>");
23MODULE_DESCRIPTION("Xtables: IPsec-ESP packet match");
24MODULE_ALIAS("ipt_esp");
25MODULE_ALIAS("ip6t_esp");
26
27/* Returns 1 if the spi is matched by the range, 0 otherwise */
28static inline bool
29spi_match(u_int32_t min, u_int32_t max, u_int32_t spi, bool invert)
30{
31 bool r;
32 pr_debug("spi_match:%c 0x%x <= 0x%x <= 0x%x\n",
33 invert ? '!' : ' ', min, spi, max);
34 r = (spi >= min && spi <= max) ^ invert;
35 pr_debug(" result %s\n", r ? "PASS" : "FAILED");
36 return r;
37}
38
39static bool esp_mt(const struct sk_buff *skb, struct xt_action_param *par)
40{
41 const struct ip_esp_hdr *eh;
42 struct ip_esp_hdr _esp;
43 const struct xt_esp *espinfo = par->matchinfo;
44
45 /* Must not be a fragment. */
46 if (par->fragoff != 0)
47 return false;
48
49 eh = skb_header_pointer(skb, par->thoff, sizeof(_esp), &_esp);
50 if (eh == NULL) {
51 /* We've been asked to examine this packet, and we
52 * can't. Hence, no choice but to drop.
53 */
54 pr_debug("Dropping evil ESP tinygram.\n");
55 par->hotdrop = true;
56 return false;
57 }
58
59 return spi_match(espinfo->spis[0], espinfo->spis[1], ntohl(eh->spi),
60 !!(espinfo->invflags & XT_ESP_INV_SPI));
61}
62
63static int esp_mt_check(const struct xt_mtchk_param *par)
64{
65 const struct xt_esp *espinfo = par->matchinfo;
66
67 if (espinfo->invflags & ~XT_ESP_INV_MASK) {
68 pr_debug("unknown flags %X\n", espinfo->invflags);
69 return -EINVAL;
70 }
71
72 return 0;
73}
74
75static struct xt_match esp_mt_reg[] __read_mostly = {
76 {
77 .name = "esp",
78 .family = NFPROTO_IPV4,
79 .checkentry = esp_mt_check,
80 .match = esp_mt,
81 .matchsize = sizeof(struct xt_esp),
82 .proto = IPPROTO_ESP,
83 .me = THIS_MODULE,
84 },
85 {
86 .name = "esp",
87 .family = NFPROTO_IPV6,
88 .checkentry = esp_mt_check,
89 .match = esp_mt,
90 .matchsize = sizeof(struct xt_esp),
91 .proto = IPPROTO_ESP,
92 .me = THIS_MODULE,
93 },
94};
95
96static int __init esp_mt_init(void)
97{
98 return xt_register_matches(esp_mt_reg, ARRAY_SIZE(esp_mt_reg));
99}
100
101static void __exit esp_mt_exit(void)
102{
103 xt_unregister_matches(esp_mt_reg, ARRAY_SIZE(esp_mt_reg));
104}
105
106module_init(esp_mt_init);
107module_exit(esp_mt_exit);