// SPDX-License-Identifier: GPL-2.0-only
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/* Kernel module to match ESP parameters. */
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/* (C) 1999-2000 Yon Uriarte <yon@astaro.de>
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/module.h>
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#include <linux/skbuff.h>
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#include <linux/in.h>
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#include <linux/ip.h>
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#include <linux/netfilter/xt_esp.h>
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#include <linux/netfilter/x_tables.h>
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#include <linux/netfilter_ipv4/ip_tables.h>
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#include <linux/netfilter_ipv6/ip6_tables.h>
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Yon Uriarte <yon@astaro.de>");
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MODULE_DESCRIPTION("Xtables: IPsec-ESP packet match");
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MODULE_ALIAS("ipt_esp");
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MODULE_ALIAS("ip6t_esp");
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/* Returns 1 if the spi is matched by the range, 0 otherwise */
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static inline bool
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spi_match(u_int32_t min, u_int32_t max, u_int32_t spi, bool invert)
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{
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bool r;
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pr_debug("spi_match:%c 0x%x <= 0x%x <= 0x%x\n",
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invert ? '!' : ' ', min, spi, max);
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r = (spi >= min && spi <= max) ^ invert;
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pr_debug(" result %s\n", r ? "PASS" : "FAILED");
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return r;
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}
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static bool esp_mt(const struct sk_buff *skb, struct xt_action_param *par)
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{
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const struct ip_esp_hdr *eh;
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struct ip_esp_hdr _esp;
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const struct xt_esp *espinfo = par->matchinfo;
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/* Must not be a fragment. */
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if (par->fragoff != 0)
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return false;
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eh = skb_header_pointer(skb, par->thoff, sizeof(_esp), &_esp);
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if (eh == NULL) {
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/* We've been asked to examine this packet, and we
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* can't. Hence, no choice but to drop.
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*/
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pr_debug("Dropping evil ESP tinygram.\n");
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par->hotdrop = true;
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return false;
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}
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return spi_match(espinfo->spis[0], espinfo->spis[1], ntohl(eh->spi),
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!!(espinfo->invflags & XT_ESP_INV_SPI));
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}
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static int esp_mt_check(const struct xt_mtchk_param *par)
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{
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const struct xt_esp *espinfo = par->matchinfo;
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if (espinfo->invflags & ~XT_ESP_INV_MASK) {
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pr_debug("unknown flags %X\n", espinfo->invflags);
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return -EINVAL;
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}
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return 0;
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}
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static struct xt_match esp_mt_reg[] __read_mostly = {
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{
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.name = "esp",
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.family = NFPROTO_IPV4,
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.checkentry = esp_mt_check,
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.match = esp_mt,
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.matchsize = sizeof(struct xt_esp),
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.proto = IPPROTO_ESP,
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.me = THIS_MODULE,
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},
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{
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.name = "esp",
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.family = NFPROTO_IPV6,
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.checkentry = esp_mt_check,
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.match = esp_mt,
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.matchsize = sizeof(struct xt_esp),
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.proto = IPPROTO_ESP,
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.me = THIS_MODULE,
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},
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};
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static int __init esp_mt_init(void)
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{
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return xt_register_matches(esp_mt_reg, ARRAY_SIZE(esp_mt_reg));
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}
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static void __exit esp_mt_exit(void)
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{
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xt_unregister_matches(esp_mt_reg, ARRAY_SIZE(esp_mt_reg));
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}
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module_init(esp_mt_init);
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module_exit(esp_mt_exit);
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