net/netfilter/xt_CONNSECMARK.c

   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 <https://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
  22 MODULE_LICENSE("GPL");
  23 MODULE_AUTHOR("James Morris <jmorris@redhat.com>");
  24 MODULE_DESCRIPTION("Xtables: target for copying between connection and security mark");
  25 MODULE_ALIAS("ipt_CONNSECMARK");
  26 MODULE_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  */
  32 static 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  */
  50 static 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
  62 static unsigned int
  63 connsecmark_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
  83 static 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
 112 static void connsecmark_tg_destroy(const struct xt_tgdtor_param *par)
 113 {
 114         nf_ct_netns_put(par->net, par->family);
 115 }
 116
 117 static 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
 128 static int __init connsecmark_tg_init(void)
 129 {
 130         return xt_register_target(&connsecmark_tg_reg);
 131 }
 132
 133 static void __exit connsecmark_tg_exit(void)
 134 {
 135         xt_unregister_target(&connsecmark_tg_reg);
 136 }
 137
 138 module_init(connsecmark_tg_init);
 139 module_exit(connsecmark_tg_exit);