LXR linux/net/netfilter/xt

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * This module is used to copy security markings from packets
   4 * to connections, and restore security markings from connections
   5 * back to packets.  This would normally be performed in conjunction
   6 * with the SECMARK target and state match.
   7 *
   8 * Based somewhat on CONNMARK:
   9 *   Copyright (C) 2002,2004 MARA Systems AB <http://www.marasystems.com>
  10 *    by Henrik Nordstrom <hno@marasystems.com>
  11 *
  12 * (C) 2006,2008 Red Hat, Inc., James Morris <jmorris@redhat.com>
  13 */
  14#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  15#include <linux/module.h>
  16#include <linux/skbuff.h>
  17#include <linux/netfilter/x_tables.h>
  18#include <linux/netfilter/xt_CONNSECMARK.h>
  19#include <net/netfilter/nf_conntrack.h>
  20#include <net/netfilter/nf_conntrack_ecache.h>
  21
  22MODULE_LICENSE("GPL");
  23MODULE_AUTHOR("James Morris <jmorris@redhat.com>");
  24MODULE_DESCRIPTION("Xtables: target for copying between connection and security mark");
  25MODULE_ALIAS("ipt_CONNSECMARK");
  26MODULE_ALIAS("ip6t_CONNSECMARK");
  27
  28/*
  29 * If the packet has a security mark and the connection does not, copy
  30 * the security mark from the packet to the connection.
  31 */
  32static void secmark_save(const struct sk_buff *skb)
  33{
  34        if (skb->secmark) {
  35                struct nf_conn *ct;
  36                enum ip_conntrack_info ctinfo;
  37
  38                ct = nf_ct_get(skb, &ctinfo);
  39                if (ct && !ct->secmark) {
  40                        ct->secmark = skb->secmark;
  41                        nf_conntrack_event_cache(IPCT_SECMARK, ct);
  42                }
  43        }
  44}
  45
  46/*
  47 * If packet has no security mark, and the connection does, restore the
  48 * security mark from the connection to the packet.
  49 */
  50static void secmark_restore(struct sk_buff *skb)
  51{
  52        if (!skb->secmark) {
  53                const struct nf_conn *ct;
  54                enum ip_conntrack_info ctinfo;
  55
  56                ct = nf_ct_get(skb, &ctinfo);
  57                if (ct && ct->secmark)
  58                        skb->secmark = ct->secmark;
  59        }
  60}
  61
  62static unsigned int
  63connsecmark_tg(struct sk_buff *skb, const struct xt_action_param *par)
  64{
  65        const struct xt_connsecmark_target_info *info = par->targinfo;
  66
  67        switch (info->mode) {
  68        case CONNSECMARK_SAVE:
  69                secmark_save(skb);
  70                break;
  71
  72        case CONNSECMARK_RESTORE:
  73                secmark_restore(skb);
  74                break;
  75
  76        default:
  77                BUG();
  78        }
  79
  80        return XT_CONTINUE;
  81}
  82
  83static int connsecmark_tg_check(const struct xt_tgchk_param *par)
  84{
  85        const struct xt_connsecmark_target_info *info = par->targinfo;
  86        int ret;
  87
  88        if (strcmp(par->table, "mangle") != 0 &&
  89            strcmp(par->table, "security") != 0) {
  90                pr_info_ratelimited("only valid in \'mangle\' or \'security\' table, not \'%s\'\n",
  91                                    par->table);
  92                return -EINVAL;
  93        }
  94
  95        switch (info->mode) {
  96        case CONNSECMARK_SAVE:
  97        case CONNSECMARK_RESTORE:
  98                break;
  99
 100        default:
 101                pr_info_ratelimited("invalid mode: %hu\n", info->mode);
 102                return -EINVAL;
 103        }
 104
 105        ret = nf_ct_netns_get(par->net, par->family);
 106        if (ret < 0)
 107                pr_info_ratelimited("cannot load conntrack support for proto=%u\n",
 108                                    par->family);
 109        return ret;
 110}
 111
 112static void connsecmark_tg_destroy(const struct xt_tgdtor_param *par)
 113{
 114        nf_ct_netns_put(par->net, par->family);
 115}
 116
 117static struct xt_target connsecmark_tg_reg __read_mostly = {
 118        .name       = "CONNSECMARK",
 119        .revision   = 0,
 120        .family     = NFPROTO_UNSPEC,
 121        .checkentry = connsecmark_tg_check,
 122        .destroy    = connsecmark_tg_destroy,
 123        .target     = connsecmark_tg,
 124        .targetsize = sizeof(struct xt_connsecmark_target_info),
 125        .me         = THIS_MODULE,
 126};
 127
 128static int __init connsecmark_tg_init(void)
 129{
 130        return xt_register_target(&connsecmark_tg_reg);
 131}
 132
 133static void __exit connsecmark_tg_exit(void)
 134{
 135        xt_unregister_target(&connsecmark_tg_reg);
 136}
 137
 138module_init(connsecmark_tg_init);
 139module_exit(connsecmark_tg_exit);
 140