// SPDX-License-Identifier: GPL-2.0-only
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/* Kernel module to match AH parameters. */
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/* (C) 2001-2002 Andras Kis-Szabo <kisza@sch.bme.hu>
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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/ip.h>
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#include <linux/ipv6.h>
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#include <linux/types.h>
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#include <net/checksum.h>
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#include <net/ipv6.h>
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#include <linux/netfilter/x_tables.h>
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#include <linux/netfilter_ipv6/ip6_tables.h>
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#include <linux/netfilter_ipv6/ip6t_ah.h>
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MODULE_LICENSE("GPL");
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MODULE_DESCRIPTION("Xtables: IPv6 IPsec-AH match");
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MODULE_AUTHOR("Andras Kis-Szabo <kisza@sch.bme.hu>");
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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 ah_mt6(const struct sk_buff *skb, struct xt_action_param *par)
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{
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struct ip_auth_hdr _ah;
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const struct ip_auth_hdr *ah;
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const struct ip6t_ah *ahinfo = par->matchinfo;
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unsigned int ptr = 0;
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unsigned int hdrlen = 0;
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int err;
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err = ipv6_find_hdr(skb, &ptr, NEXTHDR_AUTH, NULL, NULL);
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if (err < 0) {
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if (err != -ENOENT)
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par->hotdrop = true;
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return false;
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}
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ah = skb_header_pointer(skb, ptr, sizeof(_ah), &_ah);
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if (ah == NULL) {
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par->hotdrop = true;
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return false;
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}
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hdrlen = ipv6_authlen(ah);
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pr_debug("IPv6 AH LEN %u %u ", hdrlen, ah->hdrlen);
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pr_debug("RES %04X ", ah->reserved);
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pr_debug("SPI %u %08X\n", ntohl(ah->spi), ntohl(ah->spi));
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pr_debug("IPv6 AH spi %02X ",
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spi_match(ahinfo->spis[0], ahinfo->spis[1],
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ntohl(ah->spi),
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!!(ahinfo->invflags & IP6T_AH_INV_SPI)));
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pr_debug("len %02X %04X %02X ",
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ahinfo->hdrlen, hdrlen,
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(!ahinfo->hdrlen ||
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(ahinfo->hdrlen == hdrlen) ^
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!!(ahinfo->invflags & IP6T_AH_INV_LEN)));
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pr_debug("res %02X %04X %02X\n",
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ahinfo->hdrres, ah->reserved,
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!(ahinfo->hdrres && ah->reserved));
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return spi_match(ahinfo->spis[0], ahinfo->spis[1],
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ntohl(ah->spi),
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!!(ahinfo->invflags & IP6T_AH_INV_SPI)) &&
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(!ahinfo->hdrlen ||
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(ahinfo->hdrlen == hdrlen) ^
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!!(ahinfo->invflags & IP6T_AH_INV_LEN)) &&
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!(ahinfo->hdrres && ah->reserved);
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}
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static int ah_mt6_check(const struct xt_mtchk_param *par)
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{
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const struct ip6t_ah *ahinfo = par->matchinfo;
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if (ahinfo->invflags & ~IP6T_AH_INV_MASK) {
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pr_debug("unknown flags %X\n", ahinfo->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 ah_mt6_reg __read_mostly = {
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.name = "ah",
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.family = NFPROTO_IPV6,
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.match = ah_mt6,
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.matchsize = sizeof(struct ip6t_ah),
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.checkentry = ah_mt6_check,
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.me = THIS_MODULE,
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};
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static int __init ah_mt6_init(void)
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{
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return xt_register_match(&ah_mt6_reg);
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}
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static void __exit ah_mt6_exit(void)
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{
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xt_unregister_match(&ah_mt6_reg);
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}
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module_init(ah_mt6_init);
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module_exit(ah_mt6_exit);
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