net/netfilter/nf_conntrack_timeout.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * (C) 2012 by Pablo Neira Ayuso <pablo@netfilter.org>
   4  * (C) 2012 by Vyatta Inc. <http://www.vyatta.com>
   5  */
   6
   7 #include <linux/types.h>
   8 #include <linux/netfilter.h>
   9 #include <linux/skbuff.h>
  10 #include <linux/vmalloc.h>
  11 #include <linux/stddef.h>
  12 #include <linux/err.h>
  13 #include <linux/percpu.h>
  14 #include <linux/kernel.h>
  15 #include <linux/netdevice.h>
  16 #include <linux/slab.h>
  17 #include <linux/export.h>
  18
  19 #include <net/netfilter/nf_conntrack.h>
  20 #include <net/netfilter/nf_conntrack_core.h>
  21 #include <net/netfilter/nf_conntrack_extend.h>
  22 #include <net/netfilter/nf_conntrack_l4proto.h>
  23 #include <net/netfilter/nf_conntrack_timeout.h>
  24
  25 struct nf_ct_timeout *
  26 (*nf_ct_timeout_find_get_hook)(struct net *net, const char *name) __read_mostly;
  27 EXPORT_SYMBOL_GPL(nf_ct_timeout_find_get_hook);
  28
  29 void (*nf_ct_timeout_put_hook)(struct nf_ct_timeout *timeout) __read_mostly;
  30 EXPORT_SYMBOL_GPL(nf_ct_timeout_put_hook);
  31
  32 static int untimeout(struct nf_conn *ct, void *timeout)
  33 {
  34         struct nf_conn_timeout *timeout_ext = nf_ct_timeout_find(ct);
  35
  36         if (timeout_ext && (!timeout || timeout_ext->timeout == timeout))
  37                 RCU_INIT_POINTER(timeout_ext->timeout, NULL);
  38
  39         /* We are not intended to delete this conntrack. */
  40         return 0;
  41 }
  42
  43 void nf_ct_untimeout(struct net *net, struct nf_ct_timeout *timeout)
  44 {
  45         nf_ct_iterate_cleanup_net(net, untimeout, timeout, 0, 0);
  46 }
  47 EXPORT_SYMBOL_GPL(nf_ct_untimeout);
  48
  49 static void __nf_ct_timeout_put(struct nf_ct_timeout *timeout)
  50 {
  51         typeof(nf_ct_timeout_put_hook) timeout_put;
  52
  53         timeout_put = rcu_dereference(nf_ct_timeout_put_hook);
  54         if (timeout_put)
  55                 timeout_put(timeout);
  56 }
  57
  58 int nf_ct_set_timeout(struct net *net, struct nf_conn *ct,
  59                       u8 l3num, u8 l4num, const char *timeout_name)
  60 {
  61         typeof(nf_ct_timeout_find_get_hook) timeout_find_get;
  62         struct nf_ct_timeout *timeout;
  63         struct nf_conn_timeout *timeout_ext;
  64         const char *errmsg = NULL;
  65         int ret = 0;
  66
  67         rcu_read_lock();
  68         timeout_find_get = rcu_dereference(nf_ct_timeout_find_get_hook);
  69         if (!timeout_find_get) {
  70                 ret = -ENOENT;
  71                 errmsg = "Timeout policy base is empty";
  72                 goto out;
  73         }
  74
  75         timeout = timeout_find_get(net, timeout_name);
  76         if (!timeout) {
  77                 ret = -ENOENT;
  78                 pr_info_ratelimited("No such timeout policy \"%s\"\n",
  79                                     timeout_name);
  80                 goto out;
  81         }
  82
  83         if (timeout->l3num != l3num) {
  84                 ret = -EINVAL;
  85                 pr_info_ratelimited("Timeout policy `%s' can only be used by "
  86                                     "L%d protocol number %d\n",
  87                                     timeout_name, 3, timeout->l3num);
  88                 goto err_put_timeout;
  89         }
  90         /* Make sure the timeout policy matches any existing protocol tracker,
  91          * otherwise default to generic.
  92          */
  93         if (timeout->l4proto->l4proto != l4num) {
  94                 ret = -EINVAL;
  95                 pr_info_ratelimited("Timeout policy `%s' can only be used by "
  96                                     "L%d protocol number %d\n",
  97                                     timeout_name, 4, timeout->l4proto->l4proto);
  98                 goto err_put_timeout;
  99         }
 100         timeout_ext = nf_ct_timeout_ext_add(ct, timeout, GFP_ATOMIC);
 101         if (!timeout_ext) {
 102                 ret = -ENOMEM;
 103                 goto err_put_timeout;
 104         }
 105
 106         rcu_read_unlock();
 107         return ret;
 108
 109 err_put_timeout:
 110         __nf_ct_timeout_put(timeout);
 111 out:
 112         rcu_read_unlock();
 113         if (errmsg)
 114                 pr_info_ratelimited("%s\n", errmsg);
 115         return ret;
 116 }
 117 EXPORT_SYMBOL_GPL(nf_ct_set_timeout);
 118
 119 void nf_ct_destroy_timeout(struct nf_conn *ct)
 120 {
 121         struct nf_conn_timeout *timeout_ext;
 122         typeof(nf_ct_timeout_put_hook) timeout_put;
 123
 124         rcu_read_lock();
 125         timeout_put = rcu_dereference(nf_ct_timeout_put_hook);
 126
 127         if (timeout_put) {
 128                 timeout_ext = nf_ct_timeout_find(ct);
 129                 if (timeout_ext) {
 130                         timeout_put(timeout_ext->timeout);
 131                         RCU_INIT_POINTER(timeout_ext->timeout, NULL);
 132                 }
 133         }
 134         rcu_read_unlock();
 135 }
 136 EXPORT_SYMBOL_GPL(nf_ct_destroy_timeout);
 137
 138 static const struct nf_ct_ext_type timeout_extend = {
 139         .len    = sizeof(struct nf_conn_timeout),
 140         .align  = __alignof__(struct nf_conn_timeout),
 141         .id     = NF_CT_EXT_TIMEOUT,
 142 };
 143
 144 int nf_conntrack_timeout_init(void)
 145 {
 146         int ret = nf_ct_extend_register(&timeout_extend);
 147         if (ret < 0)
 148                 pr_err("nf_ct_timeout: Unable to register timeout extension.\n");
 149         return ret;
 150 }
 151
 152 void nf_conntrack_timeout_fini(void)
 153 {
 154         nf_ct_extend_unregister(&timeout_extend);
 155 }