net/sched/act_ipt.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * net/sched/act_ipt.c          iptables target interface
   4  *
   5  *TODO: Add other tables. For now we only support the ipv4 table targets
   6  *
   7  * Copyright:   Jamal Hadi Salim (2002-13)
   8  */
   9
  10 #include <linux/types.h>
  11 #include <linux/kernel.h>
  12 #include <linux/string.h>
  13 #include <linux/errno.h>
  14 #include <linux/skbuff.h>
  15 #include <linux/rtnetlink.h>
  16 #include <linux/module.h>
  17 #include <linux/init.h>
  18 #include <linux/slab.h>
  19 #include <net/netlink.h>
  20 #include <net/pkt_sched.h>
  21 #include <linux/tc_act/tc_ipt.h>
  22 #include <net/tc_act/tc_ipt.h>
  23
  24 #include <linux/netfilter_ipv4/ip_tables.h>
  25
  26
  27 static struct tc_action_ops act_ipt_ops;
  28 static struct tc_action_ops act_xt_ops;
  29
  30 static int ipt_init_target(struct net *net, struct xt_entry_target *t,
  31                            char *table, unsigned int hook)
  32 {
  33         struct xt_tgchk_param par;
  34         struct xt_target *target;
  35         struct ipt_entry e = {};
  36         int ret = 0;
  37
  38         target = xt_request_find_target(AF_INET, t->u.user.name,
  39                                         t->u.user.revision);
  40         if (IS_ERR(target))
  41                 return PTR_ERR(target);
  42
  43         t->u.kernel.target = target;
  44         memset(&par, 0, sizeof(par));
  45         par.net       = net;
  46         par.table     = table;
  47         par.entryinfo = &e;
  48         par.target    = target;
  49         par.targinfo  = t->data;
  50         par.hook_mask = hook;
  51         par.family    = NFPROTO_IPV4;
  52
  53         ret = xt_check_target(&par, t->u.target_size - sizeof(*t), 0, false);
  54         if (ret < 0) {
  55                 module_put(t->u.kernel.target->me);
  56                 return ret;
  57         }
  58         return 0;
  59 }
  60
  61 static void ipt_destroy_target(struct xt_entry_target *t, struct net *net)
  62 {
  63         struct xt_tgdtor_param par = {
  64                 .target   = t->u.kernel.target,
  65                 .targinfo = t->data,
  66                 .family   = NFPROTO_IPV4,
  67                 .net      = net,
  68         };
  69         if (par.target->destroy != NULL)
  70                 par.target->destroy(&par);
  71         module_put(par.target->me);
  72 }
  73
  74 static void tcf_ipt_release(struct tc_action *a)
  75 {
  76         struct tcf_ipt *ipt = to_ipt(a);
  77
  78         if (ipt->tcfi_t) {
  79                 ipt_destroy_target(ipt->tcfi_t, a->idrinfo->net);
  80                 kfree(ipt->tcfi_t);
  81         }
  82         kfree(ipt->tcfi_tname);
  83 }
  84
  85 static const struct nla_policy ipt_policy[TCA_IPT_MAX + 1] = {
  86         [TCA_IPT_TABLE] = { .type = NLA_STRING, .len = IFNAMSIZ },
  87         [TCA_IPT_HOOK]  = { .type = NLA_U32 },
  88         [TCA_IPT_INDEX] = { .type = NLA_U32 },
  89         [TCA_IPT_TARG]  = { .len = sizeof(struct xt_entry_target) },
  90 };
  91
  92 static int __tcf_ipt_init(struct net *net, unsigned int id, struct nlattr *nla,
  93                           struct nlattr *est, struct tc_action **a,
  94                           const struct tc_action_ops *ops,
  95                           struct tcf_proto *tp, u32 flags)
  96 {
  97         struct tc_action_net *tn = net_generic(net, id);
  98         bool bind = flags & TCA_ACT_FLAGS_BIND;
  99         struct nlattr *tb[TCA_IPT_MAX + 1];
 100         struct tcf_ipt *ipt;
 101         struct xt_entry_target *td, *t;
 102         char *tname;
 103         bool exists = false;
 104         int ret = 0, err;
 105         u32 hook = 0;
 106         u32 index = 0;
 107
 108         if (nla == NULL)
 109                 return -EINVAL;
 110
 111         err = nla_parse_nested_deprecated(tb, TCA_IPT_MAX, nla, ipt_policy,
 112                                           NULL);
 113         if (err < 0)
 114                 return err;
 115
 116         if (tb[TCA_IPT_INDEX] != NULL)
 117                 index = nla_get_u32(tb[TCA_IPT_INDEX]);
 118
 119         err = tcf_idr_check_alloc(tn, &index, a, bind);
 120         if (err < 0)
 121                 return err;
 122         exists = err;
 123         if (exists && bind)
 124                 return 0;
 125
 126         if (tb[TCA_IPT_HOOK] == NULL || tb[TCA_IPT_TARG] == NULL) {
 127                 if (exists)
 128                         tcf_idr_release(*a, bind);
 129                 else
 130                         tcf_idr_cleanup(tn, index);
 131                 return -EINVAL;
 132         }
 133
 134         td = (struct xt_entry_target *)nla_data(tb[TCA_IPT_TARG]);
 135         if (nla_len(tb[TCA_IPT_TARG]) != td->u.target_size) {
 136                 if (exists)
 137                         tcf_idr_release(*a, bind);
 138                 else
 139                         tcf_idr_cleanup(tn, index);
 140                 return -EINVAL;
 141         }
 142
 143         if (!exists) {
 144                 ret = tcf_idr_create(tn, index, est, a, ops, bind,
 145                                      false, flags);
 146                 if (ret) {
 147                         tcf_idr_cleanup(tn, index);
 148                         return ret;
 149                 }
 150                 ret = ACT_P_CREATED;
 151         } else {
 152                 if (bind)/* dont override defaults */
 153                         return 0;
 154
 155                 if (!(flags & TCA_ACT_FLAGS_REPLACE)) {
 156                         tcf_idr_release(*a, bind);
 157                         return -EEXIST;
 158                 }
 159         }
 160         hook = nla_get_u32(tb[TCA_IPT_HOOK]);
 161
 162         err = -ENOMEM;
 163         tname = kmalloc(IFNAMSIZ, GFP_KERNEL);
 164         if (unlikely(!tname))
 165                 goto err1;
 166         if (tb[TCA_IPT_TABLE] == NULL ||
 167             nla_strscpy(tname, tb[TCA_IPT_TABLE], IFNAMSIZ) >= IFNAMSIZ)
 168                 strcpy(tname, "mangle");
 169
 170         t = kmemdup(td, td->u.target_size, GFP_KERNEL);
 171         if (unlikely(!t))
 172                 goto err2;
 173
 174         err = ipt_init_target(net, t, tname, hook);
 175         if (err < 0)
 176                 goto err3;
 177
 178         ipt = to_ipt(*a);
 179
 180         spin_lock_bh(&ipt->tcf_lock);
 181         if (ret != ACT_P_CREATED) {
 182                 ipt_destroy_target(ipt->tcfi_t, net);
 183                 kfree(ipt->tcfi_tname);
 184                 kfree(ipt->tcfi_t);
 185         }
 186         ipt->tcfi_tname = tname;
 187         ipt->tcfi_t     = t;
 188         ipt->tcfi_hook  = hook;
 189         spin_unlock_bh(&ipt->tcf_lock);
 190         return ret;
 191
 192 err3:
 193         kfree(t);
 194 err2:
 195         kfree(tname);
 196 err1:
 197         tcf_idr_release(*a, bind);
 198         return err;
 199 }
 200
 201 static int tcf_ipt_init(struct net *net, struct nlattr *nla,
 202                         struct nlattr *est, struct tc_action **a,
 203                         struct tcf_proto *tp,
 204                         u32 flags, struct netlink_ext_ack *extack)
 205 {
 206         return __tcf_ipt_init(net, act_ipt_ops.net_id, nla, est,
 207                               a, &act_ipt_ops, tp, flags);
 208 }
 209
 210 static int tcf_xt_init(struct net *net, struct nlattr *nla,
 211                        struct nlattr *est, struct tc_action **a,
 212                        struct tcf_proto *tp,
 213                        u32 flags, struct netlink_ext_ack *extack)
 214 {
 215         return __tcf_ipt_init(net, act_xt_ops.net_id, nla, est,
 216                               a, &act_xt_ops, tp, flags);
 217 }
 218
 219 static int tcf_ipt_act(struct sk_buff *skb, const struct tc_action *a,
 220                        struct tcf_result *res)
 221 {
 222         int ret = 0, result = 0;
 223         struct tcf_ipt *ipt = to_ipt(a);
 224         struct xt_action_param par;
 225         struct nf_hook_state state = {
 226                 .net    = dev_net(skb->dev),
 227                 .in     = skb->dev,
 228                 .hook   = ipt->tcfi_hook,
 229                 .pf     = NFPROTO_IPV4,
 230         };
 231
 232         if (skb_unclone(skb, GFP_ATOMIC))
 233                 return TC_ACT_UNSPEC;
 234
 235         spin_lock(&ipt->tcf_lock);
 236
 237         tcf_lastuse_update(&ipt->tcf_tm);
 238         bstats_update(&ipt->tcf_bstats, skb);
 239
 240         /* yes, we have to worry about both in and out dev
 241          * worry later - danger - this API seems to have changed
 242          * from earlier kernels
 243          */
 244         par.state    = &state;
 245         par.target   = ipt->tcfi_t->u.kernel.target;
 246         par.targinfo = ipt->tcfi_t->data;
 247         ret = par.target->target(skb, &par);
 248
 249         switch (ret) {
 250         case NF_ACCEPT:
 251                 result = TC_ACT_OK;
 252                 break;
 253         case NF_DROP:
 254                 result = TC_ACT_SHOT;
 255                 ipt->tcf_qstats.drops++;
 256                 break;
 257         case XT_CONTINUE:
 258                 result = TC_ACT_PIPE;
 259                 break;
 260         default:
 261                 net_notice_ratelimited("tc filter: Bogus netfilter code %d assume ACCEPT\n",
 262                                        ret);
 263                 result = TC_ACT_OK;
 264                 break;
 265         }
 266         spin_unlock(&ipt->tcf_lock);
 267         return result;
 268
 269 }
 270
 271 static int tcf_ipt_dump(struct sk_buff *skb, struct tc_action *a, int bind,
 272                         int ref)
 273 {
 274         unsigned char *b = skb_tail_pointer(skb);
 275         struct tcf_ipt *ipt = to_ipt(a);
 276         struct xt_entry_target *t;
 277         struct tcf_t tm;
 278         struct tc_cnt c;
 279
 280         /* for simple targets kernel size == user size
 281          * user name = target name
 282          * for foolproof you need to not assume this
 283          */
 284
 285         spin_lock_bh(&ipt->tcf_lock);
 286         t = kmemdup(ipt->tcfi_t, ipt->tcfi_t->u.user.target_size, GFP_ATOMIC);
 287         if (unlikely(!t))
 288                 goto nla_put_failure;
 289
 290         c.bindcnt = atomic_read(&ipt->tcf_bindcnt) - bind;
 291         c.refcnt = refcount_read(&ipt->tcf_refcnt) - ref;
 292         strcpy(t->u.user.name, ipt->tcfi_t->u.kernel.target->name);
 293
 294         if (nla_put(skb, TCA_IPT_TARG, ipt->tcfi_t->u.user.target_size, t) ||
 295             nla_put_u32(skb, TCA_IPT_INDEX, ipt->tcf_index) ||
 296             nla_put_u32(skb, TCA_IPT_HOOK, ipt->tcfi_hook) ||
 297             nla_put(skb, TCA_IPT_CNT, sizeof(struct tc_cnt), &c) ||
 298             nla_put_string(skb, TCA_IPT_TABLE, ipt->tcfi_tname))
 299                 goto nla_put_failure;
 300
 301         tcf_tm_dump(&tm, &ipt->tcf_tm);
 302         if (nla_put_64bit(skb, TCA_IPT_TM, sizeof(tm), &tm, TCA_IPT_PAD))
 303                 goto nla_put_failure;
 304
 305         spin_unlock_bh(&ipt->tcf_lock);
 306         kfree(t);
 307         return skb->len;
 308
 309 nla_put_failure:
 310         spin_unlock_bh(&ipt->tcf_lock);
 311         nlmsg_trim(skb, b);
 312         kfree(t);
 313         return -1;
 314 }
 315
 316 static struct tc_action_ops act_ipt_ops = {
 317         .kind           =       "ipt",
 318         .id             =       TCA_ID_IPT,
 319         .owner          =       THIS_MODULE,
 320         .act            =       tcf_ipt_act,
 321         .dump           =       tcf_ipt_dump,
 322         .cleanup        =       tcf_ipt_release,
 323         .init           =       tcf_ipt_init,
 324         .size           =       sizeof(struct tcf_ipt),
 325 };
 326
 327 static __net_init int ipt_init_net(struct net *net)
 328 {
 329         struct tc_action_net *tn = net_generic(net, act_ipt_ops.net_id);
 330
 331         return tc_action_net_init(net, tn, &act_ipt_ops);
 332 }
 333
 334 static void __net_exit ipt_exit_net(struct list_head *net_list)
 335 {
 336         tc_action_net_exit(net_list, act_ipt_ops.net_id);
 337 }
 338
 339 static struct pernet_operations ipt_net_ops = {
 340         .init = ipt_init_net,
 341         .exit_batch = ipt_exit_net,
 342         .id   = &act_ipt_ops.net_id,
 343         .size = sizeof(struct tc_action_net),
 344 };
 345
 346 static struct tc_action_ops act_xt_ops = {
 347         .kind           =       "xt",
 348         .id             =       TCA_ID_XT,
 349         .owner          =       THIS_MODULE,
 350         .act            =       tcf_ipt_act,
 351         .dump           =       tcf_ipt_dump,
 352         .cleanup        =       tcf_ipt_release,
 353         .init           =       tcf_xt_init,
 354         .size           =       sizeof(struct tcf_ipt),
 355 };
 356
 357 static __net_init int xt_init_net(struct net *net)
 358 {
 359         struct tc_action_net *tn = net_generic(net, act_xt_ops.net_id);
 360
 361         return tc_action_net_init(net, tn, &act_xt_ops);
 362 }
 363
 364 static void __net_exit xt_exit_net(struct list_head *net_list)
 365 {
 366         tc_action_net_exit(net_list, act_xt_ops.net_id);
 367 }
 368
 369 static struct pernet_operations xt_net_ops = {
 370         .init = xt_init_net,
 371         .exit_batch = xt_exit_net,
 372         .id   = &act_xt_ops.net_id,
 373         .size = sizeof(struct tc_action_net),
 374 };
 375
 376 MODULE_AUTHOR("Jamal Hadi Salim(2002-13)");
 377 MODULE_DESCRIPTION("Iptables target actions");
 378 MODULE_LICENSE("GPL");
 379 MODULE_ALIAS("act_xt");
 380
 381 static int __init ipt_init_module(void)
 382 {
 383         int ret1, ret2;
 384
 385         ret1 = tcf_register_action(&act_xt_ops, &xt_net_ops);
 386         if (ret1 < 0)
 387                 pr_err("Failed to load xt action\n");
 388
 389         ret2 = tcf_register_action(&act_ipt_ops, &ipt_net_ops);
 390         if (ret2 < 0)
 391                 pr_err("Failed to load ipt action\n");
 392
 393         if (ret1 < 0 && ret2 < 0) {
 394                 return ret1;
 395         } else
 396                 return 0;
 397 }
 398
 399 static void __exit ipt_cleanup_module(void)
 400 {
 401         tcf_unregister_action(&act_ipt_ops, &ipt_net_ops);
 402         tcf_unregister_action(&act_xt_ops, &xt_net_ops);
 403 }
 404
 405 module_init(ipt_init_module);
 406 module_exit(ipt_cleanup_module);