net/netfilter/nfnetlink_acct.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * (C) 2011 Pablo Neira Ayuso <pablo@netfilter.org>
   4  * (C) 2011 Intra2net AG <https://www.intra2net.com>
   5  */
   6 #include <linux/init.h>
   7 #include <linux/module.h>
   8 #include <linux/kernel.h>
   9 #include <linux/skbuff.h>
  10 #include <linux/atomic.h>
  11 #include <linux/refcount.h>
  12 #include <linux/netlink.h>
  13 #include <linux/rculist.h>
  14 #include <linux/slab.h>
  15 #include <linux/types.h>
  16 #include <linux/errno.h>
  17 #include <net/netlink.h>
  18 #include <net/sock.h>
  19 #include <net/netns/generic.h>
  20
  21 #include <linux/netfilter.h>
  22 #include <linux/netfilter/nfnetlink.h>
  23 #include <linux/netfilter/nfnetlink_acct.h>
  24
  25 MODULE_LICENSE("GPL");
  26 MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
  27 MODULE_DESCRIPTION("nfacct: Extended Netfilter accounting infrastructure");
  28
  29 struct nf_acct {
  30         atomic64_t              pkts;
  31         atomic64_t              bytes;
  32         unsigned long           flags;
  33         struct list_head        head;
  34         refcount_t              refcnt;
  35         char                    name[NFACCT_NAME_MAX];
  36         struct rcu_head         rcu_head;
  37         char                    data[];
  38 };
  39
  40 struct nfacct_filter {
  41         u32 value;
  42         u32 mask;
  43 };
  44
  45 struct nfnl_acct_net {
  46         struct list_head        nfnl_acct_list;
  47 };
  48
  49 static unsigned int nfnl_acct_net_id __read_mostly;
  50
  51 static inline struct nfnl_acct_net *nfnl_acct_pernet(struct net *net)
  52 {
  53         return net_generic(net, nfnl_acct_net_id);
  54 }
  55
  56 #define NFACCT_F_QUOTA (NFACCT_F_QUOTA_PKTS | NFACCT_F_QUOTA_BYTES)
  57 #define NFACCT_OVERQUOTA_BIT    2       /* NFACCT_F_OVERQUOTA */
  58
  59 static int nfnl_acct_new(struct net *net, struct sock *nfnl,
  60                          struct sk_buff *skb, const struct nlmsghdr *nlh,
  61                          const struct nlattr * const tb[],
  62                          struct netlink_ext_ack *extack)
  63 {
  64         struct nfnl_acct_net *nfnl_acct_net = nfnl_acct_pernet(net);
  65         struct nf_acct *nfacct, *matching = NULL;
  66         char *acct_name;
  67         unsigned int size = 0;
  68         u32 flags = 0;
  69
  70         if (!tb[NFACCT_NAME])
  71                 return -EINVAL;
  72
  73         acct_name = nla_data(tb[NFACCT_NAME]);
  74         if (strlen(acct_name) == 0)
  75                 return -EINVAL;
  76
  77         list_for_each_entry(nfacct, &nfnl_acct_net->nfnl_acct_list, head) {
  78                 if (strncmp(nfacct->name, acct_name, NFACCT_NAME_MAX) != 0)
  79                         continue;
  80
  81                 if (nlh->nlmsg_flags & NLM_F_EXCL)
  82                         return -EEXIST;
  83
  84                 matching = nfacct;
  85                 break;
  86         }
  87
  88         if (matching) {
  89                 if (nlh->nlmsg_flags & NLM_F_REPLACE) {
  90                         /* reset counters if you request a replacement. */
  91                         atomic64_set(&matching->pkts, 0);
  92                         atomic64_set(&matching->bytes, 0);
  93                         smp_mb__before_atomic();
  94                         /* reset overquota flag if quota is enabled. */
  95                         if ((matching->flags & NFACCT_F_QUOTA))
  96                                 clear_bit(NFACCT_OVERQUOTA_BIT,
  97                                           &matching->flags);
  98                         return 0;
  99                 }
 100                 return -EBUSY;
 101         }
 102
 103         if (tb[NFACCT_FLAGS]) {
 104                 flags = ntohl(nla_get_be32(tb[NFACCT_FLAGS]));
 105                 if (flags & ~NFACCT_F_QUOTA)
 106                         return -EOPNOTSUPP;
 107                 if ((flags & NFACCT_F_QUOTA) == NFACCT_F_QUOTA)
 108                         return -EINVAL;
 109                 if (flags & NFACCT_F_OVERQUOTA)
 110                         return -EINVAL;
 111                 if ((flags & NFACCT_F_QUOTA) && !tb[NFACCT_QUOTA])
 112                         return -EINVAL;
 113
 114                 size += sizeof(u64);
 115         }
 116
 117         nfacct = kzalloc(sizeof(struct nf_acct) + size, GFP_KERNEL);
 118         if (nfacct == NULL)
 119                 return -ENOMEM;
 120
 121         if (flags & NFACCT_F_QUOTA) {
 122                 u64 *quota = (u64 *)nfacct->data;
 123
 124                 *quota = be64_to_cpu(nla_get_be64(tb[NFACCT_QUOTA]));
 125                 nfacct->flags = flags;
 126         }
 127
 128         nla_strscpy(nfacct->name, tb[NFACCT_NAME], NFACCT_NAME_MAX);
 129
 130         if (tb[NFACCT_BYTES]) {
 131                 atomic64_set(&nfacct->bytes,
 132                              be64_to_cpu(nla_get_be64(tb[NFACCT_BYTES])));
 133         }
 134         if (tb[NFACCT_PKTS]) {
 135                 atomic64_set(&nfacct->pkts,
 136                              be64_to_cpu(nla_get_be64(tb[NFACCT_PKTS])));
 137         }
 138         refcount_set(&nfacct->refcnt, 1);
 139         list_add_tail_rcu(&nfacct->head, &nfnl_acct_net->nfnl_acct_list);
 140         return 0;
 141 }
 142
 143 static int
 144 nfnl_acct_fill_info(struct sk_buff *skb, u32 portid, u32 seq, u32 type,
 145                    int event, struct nf_acct *acct)
 146 {
 147         struct nlmsghdr *nlh;
 148         struct nfgenmsg *nfmsg;
 149         unsigned int flags = portid ? NLM_F_MULTI : 0;
 150         u64 pkts, bytes;
 151         u32 old_flags;
 152
 153         event = nfnl_msg_type(NFNL_SUBSYS_ACCT, event);
 154         nlh = nlmsg_put(skb, portid, seq, event, sizeof(*nfmsg), flags);
 155         if (nlh == NULL)
 156                 goto nlmsg_failure;
 157
 158         nfmsg = nlmsg_data(nlh);
 159         nfmsg->nfgen_family = AF_UNSPEC;
 160         nfmsg->version = NFNETLINK_V0;
 161         nfmsg->res_id = 0;
 162
 163         if (nla_put_string(skb, NFACCT_NAME, acct->name))
 164                 goto nla_put_failure;
 165
 166         old_flags = acct->flags;
 167         if (type == NFNL_MSG_ACCT_GET_CTRZERO) {
 168                 pkts = atomic64_xchg(&acct->pkts, 0);
 169                 bytes = atomic64_xchg(&acct->bytes, 0);
 170                 smp_mb__before_atomic();
 171                 if (acct->flags & NFACCT_F_QUOTA)
 172                         clear_bit(NFACCT_OVERQUOTA_BIT, &acct->flags);
 173         } else {
 174                 pkts = atomic64_read(&acct->pkts);
 175                 bytes = atomic64_read(&acct->bytes);
 176         }
 177         if (nla_put_be64(skb, NFACCT_PKTS, cpu_to_be64(pkts),
 178                          NFACCT_PAD) ||
 179             nla_put_be64(skb, NFACCT_BYTES, cpu_to_be64(bytes),
 180                          NFACCT_PAD) ||
 181             nla_put_be32(skb, NFACCT_USE, htonl(refcount_read(&acct->refcnt))))
 182                 goto nla_put_failure;
 183         if (acct->flags & NFACCT_F_QUOTA) {
 184                 u64 *quota = (u64 *)acct->data;
 185
 186                 if (nla_put_be32(skb, NFACCT_FLAGS, htonl(old_flags)) ||
 187                     nla_put_be64(skb, NFACCT_QUOTA, cpu_to_be64(*quota),
 188                                  NFACCT_PAD))
 189                         goto nla_put_failure;
 190         }
 191         nlmsg_end(skb, nlh);
 192         return skb->len;
 193
 194 nlmsg_failure:
 195 nla_put_failure:
 196         nlmsg_cancel(skb, nlh);
 197         return -1;
 198 }
 199
 200 static int
 201 nfnl_acct_dump(struct sk_buff *skb, struct netlink_callback *cb)
 202 {
 203         struct net *net = sock_net(skb->sk);
 204         struct nfnl_acct_net *nfnl_acct_net = nfnl_acct_pernet(net);
 205         struct nf_acct *cur, *last;
 206         const struct nfacct_filter *filter = cb->data;
 207
 208         if (cb->args[2])
 209                 return 0;
 210
 211         last = (struct nf_acct *)cb->args[1];
 212         if (cb->args[1])
 213                 cb->args[1] = 0;
 214
 215         rcu_read_lock();
 216         list_for_each_entry_rcu(cur, &nfnl_acct_net->nfnl_acct_list, head) {
 217                 if (last) {
 218                         if (cur != last)
 219                                 continue;
 220
 221                         last = NULL;
 222                 }
 223
 224                 if (filter && (cur->flags & filter->mask) != filter->value)
 225                         continue;
 226
 227                 if (nfnl_acct_fill_info(skb, NETLINK_CB(cb->skb).portid,
 228                                        cb->nlh->nlmsg_seq,
 229                                        NFNL_MSG_TYPE(cb->nlh->nlmsg_type),
 230                                        NFNL_MSG_ACCT_NEW, cur) < 0) {
 231                         cb->args[1] = (unsigned long)cur;
 232                         break;
 233                 }
 234         }
 235         if (!cb->args[1])
 236                 cb->args[2] = 1;
 237         rcu_read_unlock();
 238         return skb->len;
 239 }
 240
 241 static int nfnl_acct_done(struct netlink_callback *cb)
 242 {
 243         kfree(cb->data);
 244         return 0;
 245 }
 246
 247 static const struct nla_policy filter_policy[NFACCT_FILTER_MAX + 1] = {
 248         [NFACCT_FILTER_MASK]    = { .type = NLA_U32 },
 249         [NFACCT_FILTER_VALUE]   = { .type = NLA_U32 },
 250 };
 251
 252 static int nfnl_acct_start(struct netlink_callback *cb)
 253 {
 254         const struct nlattr *const attr = cb->data;
 255         struct nlattr *tb[NFACCT_FILTER_MAX + 1];
 256         struct nfacct_filter *filter;
 257         int err;
 258
 259         if (!attr)
 260                 return 0;
 261
 262         err = nla_parse_nested_deprecated(tb, NFACCT_FILTER_MAX, attr,
 263                                           filter_policy, NULL);
 264         if (err < 0)
 265                 return err;
 266
 267         if (!tb[NFACCT_FILTER_MASK] || !tb[NFACCT_FILTER_VALUE])
 268                 return -EINVAL;
 269
 270         filter = kzalloc(sizeof(struct nfacct_filter), GFP_KERNEL);
 271         if (!filter)
 272                 return -ENOMEM;
 273
 274         filter->mask = ntohl(nla_get_be32(tb[NFACCT_FILTER_MASK]));
 275         filter->value = ntohl(nla_get_be32(tb[NFACCT_FILTER_VALUE]));
 276         cb->data = filter;
 277
 278         return 0;
 279 }
 280
 281 static int nfnl_acct_get(struct net *net, struct sock *nfnl,
 282                          struct sk_buff *skb, const struct nlmsghdr *nlh,
 283                          const struct nlattr * const tb[],
 284                          struct netlink_ext_ack *extack)
 285 {
 286         struct nfnl_acct_net *nfnl_acct_net = nfnl_acct_pernet(net);
 287         int ret = -ENOENT;
 288         struct nf_acct *cur;
 289         char *acct_name;
 290
 291         if (nlh->nlmsg_flags & NLM_F_DUMP) {
 292                 struct netlink_dump_control c = {
 293                         .dump = nfnl_acct_dump,
 294                         .start = nfnl_acct_start,
 295                         .done = nfnl_acct_done,
 296                         .data = (void *)tb[NFACCT_FILTER],
 297                 };
 298
 299                 return netlink_dump_start(nfnl, skb, nlh, &c);
 300         }
 301
 302         if (!tb[NFACCT_NAME])
 303                 return -EINVAL;
 304         acct_name = nla_data(tb[NFACCT_NAME]);
 305
 306         list_for_each_entry(cur, &nfnl_acct_net->nfnl_acct_list, head) {
 307                 struct sk_buff *skb2;
 308
 309                 if (strncmp(cur->name, acct_name, NFACCT_NAME_MAX)!= 0)
 310                         continue;
 311
 312                 skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 313                 if (skb2 == NULL) {
 314                         ret = -ENOMEM;
 315                         break;
 316                 }
 317
 318                 ret = nfnl_acct_fill_info(skb2, NETLINK_CB(skb).portid,
 319                                          nlh->nlmsg_seq,
 320                                          NFNL_MSG_TYPE(nlh->nlmsg_type),
 321                                          NFNL_MSG_ACCT_NEW, cur);
 322                 if (ret <= 0) {
 323                         kfree_skb(skb2);
 324                         break;
 325                 }
 326                 ret = netlink_unicast(nfnl, skb2, NETLINK_CB(skb).portid,
 327                                         MSG_DONTWAIT);
 328                 if (ret > 0)
 329                         ret = 0;
 330
 331                 /* this avoids a loop in nfnetlink. */
 332                 return ret == -EAGAIN ? -ENOBUFS : ret;
 333         }
 334         return ret;
 335 }
 336
 337 /* try to delete object, fail if it is still in use. */
 338 static int nfnl_acct_try_del(struct nf_acct *cur)
 339 {
 340         int ret = 0;
 341
 342         /* We want to avoid races with nfnl_acct_put. So only when the current
 343          * refcnt is 1, we decrease it to 0.
 344          */
 345         if (refcount_dec_if_one(&cur->refcnt)) {
 346                 /* We are protected by nfnl mutex. */
 347                 list_del_rcu(&cur->head);
 348                 kfree_rcu(cur, rcu_head);
 349         } else {
 350                 ret = -EBUSY;
 351         }
 352         return ret;
 353 }
 354
 355 static int nfnl_acct_del(struct net *net, struct sock *nfnl,
 356                          struct sk_buff *skb, const struct nlmsghdr *nlh,
 357                          const struct nlattr * const tb[],
 358                          struct netlink_ext_ack *extack)
 359 {
 360         struct nfnl_acct_net *nfnl_acct_net = nfnl_acct_pernet(net);
 361         struct nf_acct *cur, *tmp;
 362         int ret = -ENOENT;
 363         char *acct_name;
 364
 365         if (!tb[NFACCT_NAME]) {
 366                 list_for_each_entry_safe(cur, tmp, &nfnl_acct_net->nfnl_acct_list, head)
 367                         nfnl_acct_try_del(cur);
 368
 369                 return 0;
 370         }
 371         acct_name = nla_data(tb[NFACCT_NAME]);
 372
 373         list_for_each_entry(cur, &nfnl_acct_net->nfnl_acct_list, head) {
 374                 if (strncmp(cur->name, acct_name, NFACCT_NAME_MAX) != 0)
 375                         continue;
 376
 377                 ret = nfnl_acct_try_del(cur);
 378                 if (ret < 0)
 379                         return ret;
 380
 381                 break;
 382         }
 383         return ret;
 384 }
 385
 386 static const struct nla_policy nfnl_acct_policy[NFACCT_MAX+1] = {
 387         [NFACCT_NAME] = { .type = NLA_NUL_STRING, .len = NFACCT_NAME_MAX-1 },
 388         [NFACCT_BYTES] = { .type = NLA_U64 },
 389         [NFACCT_PKTS] = { .type = NLA_U64 },
 390         [NFACCT_FLAGS] = { .type = NLA_U32 },
 391         [NFACCT_QUOTA] = { .type = NLA_U64 },
 392         [NFACCT_FILTER] = {.type = NLA_NESTED },
 393 };
 394
 395 static const struct nfnl_callback nfnl_acct_cb[NFNL_MSG_ACCT_MAX] = {
 396         [NFNL_MSG_ACCT_NEW]             = { .call = nfnl_acct_new,
 397                                             .attr_count = NFACCT_MAX,
 398                                             .policy = nfnl_acct_policy },
 399         [NFNL_MSG_ACCT_GET]             = { .call = nfnl_acct_get,
 400                                             .attr_count = NFACCT_MAX,
 401                                             .policy = nfnl_acct_policy },
 402         [NFNL_MSG_ACCT_GET_CTRZERO]     = { .call = nfnl_acct_get,
 403                                             .attr_count = NFACCT_MAX,
 404                                             .policy = nfnl_acct_policy },
 405         [NFNL_MSG_ACCT_DEL]             = { .call = nfnl_acct_del,
 406                                             .attr_count = NFACCT_MAX,
 407                                             .policy = nfnl_acct_policy },
 408 };
 409
 410 static const struct nfnetlink_subsystem nfnl_acct_subsys = {
 411         .name                           = "acct",
 412         .subsys_id                      = NFNL_SUBSYS_ACCT,
 413         .cb_count                       = NFNL_MSG_ACCT_MAX,
 414         .cb                             = nfnl_acct_cb,
 415 };
 416
 417 MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_ACCT);
 418
 419 struct nf_acct *nfnl_acct_find_get(struct net *net, const char *acct_name)
 420 {
 421         struct nfnl_acct_net *nfnl_acct_net = nfnl_acct_pernet(net);
 422         struct nf_acct *cur, *acct = NULL;
 423
 424         rcu_read_lock();
 425         list_for_each_entry_rcu(cur, &nfnl_acct_net->nfnl_acct_list, head) {
 426                 if (strncmp(cur->name, acct_name, NFACCT_NAME_MAX)!= 0)
 427                         continue;
 428
 429                 if (!try_module_get(THIS_MODULE))
 430                         goto err;
 431
 432                 if (!refcount_inc_not_zero(&cur->refcnt)) {
 433                         module_put(THIS_MODULE);
 434                         goto err;
 435                 }
 436
 437                 acct = cur;
 438                 break;
 439         }
 440 err:
 441         rcu_read_unlock();
 442         return acct;
 443 }
 444 EXPORT_SYMBOL_GPL(nfnl_acct_find_get);
 445
 446 void nfnl_acct_put(struct nf_acct *acct)
 447 {
 448         if (refcount_dec_and_test(&acct->refcnt))
 449                 kfree_rcu(acct, rcu_head);
 450
 451         module_put(THIS_MODULE);
 452 }
 453 EXPORT_SYMBOL_GPL(nfnl_acct_put);
 454
 455 void nfnl_acct_update(const struct sk_buff *skb, struct nf_acct *nfacct)
 456 {
 457         atomic64_inc(&nfacct->pkts);
 458         atomic64_add(skb->len, &nfacct->bytes);
 459 }
 460 EXPORT_SYMBOL_GPL(nfnl_acct_update);
 461
 462 static void nfnl_overquota_report(struct net *net, struct nf_acct *nfacct)
 463 {
 464         int ret;
 465         struct sk_buff *skb;
 466
 467         skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_ATOMIC);
 468         if (skb == NULL)
 469                 return;
 470
 471         ret = nfnl_acct_fill_info(skb, 0, 0, NFNL_MSG_ACCT_OVERQUOTA, 0,
 472                                   nfacct);
 473         if (ret <= 0) {
 474                 kfree_skb(skb);
 475                 return;
 476         }
 477         netlink_broadcast(net->nfnl, skb, 0, NFNLGRP_ACCT_QUOTA,
 478                           GFP_ATOMIC);
 479 }
 480
 481 int nfnl_acct_overquota(struct net *net, struct nf_acct *nfacct)
 482 {
 483         u64 now;
 484         u64 *quota;
 485         int ret = NFACCT_UNDERQUOTA;
 486
 487         /* no place here if we don't have a quota */
 488         if (!(nfacct->flags & NFACCT_F_QUOTA))
 489                 return NFACCT_NO_QUOTA;
 490
 491         quota = (u64 *)nfacct->data;
 492         now = (nfacct->flags & NFACCT_F_QUOTA_PKTS) ?
 493                atomic64_read(&nfacct->pkts) : atomic64_read(&nfacct->bytes);
 494
 495         ret = now > *quota;
 496
 497         if (now >= *quota &&
 498             !test_and_set_bit(NFACCT_OVERQUOTA_BIT, &nfacct->flags)) {
 499                 nfnl_overquota_report(net, nfacct);
 500         }
 501
 502         return ret;
 503 }
 504 EXPORT_SYMBOL_GPL(nfnl_acct_overquota);
 505
 506 static int __net_init nfnl_acct_net_init(struct net *net)
 507 {
 508         INIT_LIST_HEAD(&nfnl_acct_pernet(net)->nfnl_acct_list);
 509
 510         return 0;
 511 }
 512
 513 static void __net_exit nfnl_acct_net_exit(struct net *net)
 514 {
 515         struct nfnl_acct_net *nfnl_acct_net = nfnl_acct_pernet(net);
 516         struct nf_acct *cur, *tmp;
 517
 518         list_for_each_entry_safe(cur, tmp, &nfnl_acct_net->nfnl_acct_list, head) {
 519                 list_del_rcu(&cur->head);
 520
 521                 if (refcount_dec_and_test(&cur->refcnt))
 522                         kfree_rcu(cur, rcu_head);
 523         }
 524 }
 525
 526 static struct pernet_operations nfnl_acct_ops = {
 527         .init   = nfnl_acct_net_init,
 528         .exit   = nfnl_acct_net_exit,
 529         .id     = &nfnl_acct_net_id,
 530         .size   = sizeof(struct nfnl_acct_net),
 531 };
 532
 533 static int __init nfnl_acct_init(void)
 534 {
 535         int ret;
 536
 537         ret = register_pernet_subsys(&nfnl_acct_ops);
 538         if (ret < 0) {
 539                 pr_err("nfnl_acct_init: failed to register pernet ops\n");
 540                 goto err_out;
 541         }
 542
 543         ret = nfnetlink_subsys_register(&nfnl_acct_subsys);
 544         if (ret < 0) {
 545                 pr_err("nfnl_acct_init: cannot register with nfnetlink.\n");
 546                 goto cleanup_pernet;
 547         }
 548         return 0;
 549
 550 cleanup_pernet:
 551         unregister_pernet_subsys(&nfnl_acct_ops);
 552 err_out:
 553         return ret;
 554 }
 555
 556 static void __exit nfnl_acct_exit(void)
 557 {
 558         nfnetlink_subsys_unregister(&nfnl_acct_subsys);
 559         unregister_pernet_subsys(&nfnl_acct_ops);
 560 }
 561
 562 module_init(nfnl_acct_init);
 563 module_exit(nfnl_acct_exit);