// SPDX-License-Identifier: GPL-2.0-or-later
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/* Kernel module to match IPComp parameters for IPv4 and IPv6
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*
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* Copyright (C) 2013 WindRiver
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*
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* Author:
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* Fan Du <fan.du@windriver.com>
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*
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* Based on:
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* net/netfilter/xt_esp.c
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/in.h>
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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/netfilter/xt_ipcomp.h>
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#include <linux/netfilter/x_tables.h>
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Fan Du <fan.du@windriver.com>");
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MODULE_DESCRIPTION("Xtables: IPv4/6 IPsec-IPComp SPI match");
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MODULE_ALIAS("ipt_ipcomp");
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MODULE_ALIAS("ip6t_ipcomp");
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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 comp_mt(const struct sk_buff *skb, struct xt_action_param *par)
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{
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struct ip_comp_hdr _comphdr;
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const struct ip_comp_hdr *chdr;
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const struct xt_ipcomp *compinfo = 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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chdr = skb_header_pointer(skb, par->thoff, sizeof(_comphdr), &_comphdr);
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if (chdr == 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 IPComp 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(compinfo->spis[0], compinfo->spis[1],
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ntohs(chdr->cpi),
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!!(compinfo->invflags & XT_IPCOMP_INV_SPI));
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}
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static int comp_mt_check(const struct xt_mtchk_param *par)
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{
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const struct xt_ipcomp *compinfo = par->matchinfo;
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/* Must specify no unknown invflags */
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if (compinfo->invflags & ~XT_IPCOMP_INV_MASK) {
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pr_info_ratelimited("unknown flags %X\n", compinfo->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 comp_mt_reg[] __read_mostly = {
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{
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.name = "ipcomp",
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.family = NFPROTO_IPV4,
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.match = comp_mt,
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.matchsize = sizeof(struct xt_ipcomp),
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.proto = IPPROTO_COMP,
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.checkentry = comp_mt_check,
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.me = THIS_MODULE,
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},
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{
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.name = "ipcomp",
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.family = NFPROTO_IPV6,
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.match = comp_mt,
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.matchsize = sizeof(struct xt_ipcomp),
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.proto = IPPROTO_COMP,
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.checkentry = comp_mt_check,
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.me = THIS_MODULE,
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},
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};
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static int __init comp_mt_init(void)
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{
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return xt_register_matches(comp_mt_reg, ARRAY_SIZE(comp_mt_reg));
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}
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static void __exit comp_mt_exit(void)
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{
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xt_unregister_matches(comp_mt_reg, ARRAY_SIZE(comp_mt_reg));
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}
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module_init(comp_mt_init);
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module_exit(comp_mt_exit);
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