net/netfilter/nfnetlink_acct.c

   1 /*
   2  * (C) 2011 Pablo Neira Ayuso <pablo@netfilter.org>
   3  * (C) 2011 Intra2net AG <http://www.intra2net.com>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License version 2 as
   7  * published by the Free Software Foundation (or any later at your option).
   8  */
   9 #include <linux/init.h>
  10 #include <linux/module.h>
  11 #include <linux/kernel.h>
  12 #include <linux/skbuff.h>
  13 #include <linux/atomic.h>
  14 #include <linux/netlink.h>
  15 #include <linux/rculist.h>
  16 #include <linux/slab.h>
  17 #include <linux/types.h>
  18 #include <linux/errno.h>
  19 #include <net/netlink.h>
  20 #include <net/sock.h>
  21
  22 #include <linux/netfilter.h>
  23 #include <linux/netfilter/nfnetlink.h>
  24 #include <linux/netfilter/nfnetlink_acct.h>
  25
  26 MODULE_LICENSE("GPL");
  27 MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
  28 MODULE_DESCRIPTION("nfacct: Extended Netfilter accounting infrastructure");
  29
  30 static LIST_HEAD(nfnl_acct_list);
  31
  32 struct nf_acct {
  33         atomic64_t              pkts;
  34         atomic64_t              bytes;
  35         struct list_head        head;
  36         atomic_t                refcnt;
  37         char                    name[NFACCT_NAME_MAX];
  38         struct rcu_head         rcu_head;
  39 };
  40
  41 static int
  42 nfnl_acct_new(struct sock *nfnl, struct sk_buff *skb,
  43              const struct nlmsghdr *nlh, const struct nlattr * const tb[])
  44 {
  45         struct nf_acct *nfacct, *matching = NULL;
  46         char *acct_name;
  47
  48         if (!tb[NFACCT_NAME])
  49                 return -EINVAL;
  50
  51         acct_name = nla_data(tb[NFACCT_NAME]);
  52         if (strlen(acct_name) == 0)
  53                 return -EINVAL;
  54
  55         list_for_each_entry(nfacct, &nfnl_acct_list, head) {
  56                 if (strncmp(nfacct->name, acct_name, NFACCT_NAME_MAX) != 0)
  57                         continue;
  58
  59                 if (nlh->nlmsg_flags & NLM_F_EXCL)
  60                         return -EEXIST;
  61
  62                 matching = nfacct;
  63                 break;
  64         }
  65
  66         if (matching) {
  67                 if (nlh->nlmsg_flags & NLM_F_REPLACE) {
  68                         /* reset counters if you request a replacement. */
  69                         atomic64_set(&matching->pkts, 0);
  70                         atomic64_set(&matching->bytes, 0);
  71                         return 0;
  72                 }
  73                 return -EBUSY;
  74         }
  75
  76         nfacct = kzalloc(sizeof(struct nf_acct), GFP_KERNEL);
  77         if (nfacct == NULL)
  78                 return -ENOMEM;
  79
  80         strncpy(nfacct->name, nla_data(tb[NFACCT_NAME]), NFACCT_NAME_MAX);
  81
  82         if (tb[NFACCT_BYTES]) {
  83                 atomic64_set(&nfacct->bytes,
  84                              be64_to_cpu(nla_get_be64(tb[NFACCT_BYTES])));
  85         }
  86         if (tb[NFACCT_PKTS]) {
  87                 atomic64_set(&nfacct->pkts,
  88                              be64_to_cpu(nla_get_be64(tb[NFACCT_PKTS])));
  89         }
  90         atomic_set(&nfacct->refcnt, 1);
  91         list_add_tail_rcu(&nfacct->head, &nfnl_acct_list);
  92         return 0;
  93 }
  94
  95 static int
  96 nfnl_acct_fill_info(struct sk_buff *skb, u32 portid, u32 seq, u32 type,
  97                    int event, struct nf_acct *acct)
  98 {
  99         struct nlmsghdr *nlh;
 100         struct nfgenmsg *nfmsg;
 101         unsigned int flags = portid ? NLM_F_MULTI : 0;
 102         u64 pkts, bytes;
 103
 104         event |= NFNL_SUBSYS_ACCT << 8;
 105         nlh = nlmsg_put(skb, portid, seq, event, sizeof(*nfmsg), flags);
 106         if (nlh == NULL)
 107                 goto nlmsg_failure;
 108
 109         nfmsg = nlmsg_data(nlh);
 110         nfmsg->nfgen_family = AF_UNSPEC;
 111         nfmsg->version = NFNETLINK_V0;
 112         nfmsg->res_id = 0;
 113
 114         if (nla_put_string(skb, NFACCT_NAME, acct->name))
 115                 goto nla_put_failure;
 116
 117         if (type == NFNL_MSG_ACCT_GET_CTRZERO) {
 118                 pkts = atomic64_xchg(&acct->pkts, 0);
 119                 bytes = atomic64_xchg(&acct->bytes, 0);
 120         } else {
 121                 pkts = atomic64_read(&acct->pkts);
 122                 bytes = atomic64_read(&acct->bytes);
 123         }
 124         if (nla_put_be64(skb, NFACCT_PKTS, cpu_to_be64(pkts)) ||
 125             nla_put_be64(skb, NFACCT_BYTES, cpu_to_be64(bytes)) ||
 126             nla_put_be32(skb, NFACCT_USE, htonl(atomic_read(&acct->refcnt))))
 127                 goto nla_put_failure;
 128
 129         nlmsg_end(skb, nlh);
 130         return skb->len;
 131
 132 nlmsg_failure:
 133 nla_put_failure:
 134         nlmsg_cancel(skb, nlh);
 135         return -1;
 136 }
 137
 138 static int
 139 nfnl_acct_dump(struct sk_buff *skb, struct netlink_callback *cb)
 140 {
 141         struct nf_acct *cur, *last;
 142
 143         if (cb->args[2])
 144                 return 0;
 145
 146         last = (struct nf_acct *)cb->args[1];
 147         if (cb->args[1])
 148                 cb->args[1] = 0;
 149
 150         rcu_read_lock();
 151         list_for_each_entry_rcu(cur, &nfnl_acct_list, head) {
 152                 if (last && cur != last)
 153                         continue;
 154
 155                 if (nfnl_acct_fill_info(skb, NETLINK_CB(cb->skb).portid,
 156                                        cb->nlh->nlmsg_seq,
 157                                        NFNL_MSG_TYPE(cb->nlh->nlmsg_type),
 158                                        NFNL_MSG_ACCT_NEW, cur) < 0) {
 159                         cb->args[1] = (unsigned long)cur;
 160                         break;
 161                 }
 162         }
 163         if (!cb->args[1])
 164                 cb->args[2] = 1;
 165         rcu_read_unlock();
 166         return skb->len;
 167 }
 168
 169 static int
 170 nfnl_acct_get(struct sock *nfnl, struct sk_buff *skb,
 171              const struct nlmsghdr *nlh, const struct nlattr * const tb[])
 172 {
 173         int ret = -ENOENT;
 174         struct nf_acct *cur;
 175         char *acct_name;
 176
 177         if (nlh->nlmsg_flags & NLM_F_DUMP) {
 178                 struct netlink_dump_control c = {
 179                         .dump = nfnl_acct_dump,
 180                 };
 181                 return netlink_dump_start(nfnl, skb, nlh, &c);
 182         }
 183
 184         if (!tb[NFACCT_NAME])
 185                 return -EINVAL;
 186         acct_name = nla_data(tb[NFACCT_NAME]);
 187
 188         list_for_each_entry(cur, &nfnl_acct_list, head) {
 189                 struct sk_buff *skb2;
 190
 191                 if (strncmp(cur->name, acct_name, NFACCT_NAME_MAX)!= 0)
 192                         continue;
 193
 194                 skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 195                 if (skb2 == NULL) {
 196                         ret = -ENOMEM;
 197                         break;
 198                 }
 199
 200                 ret = nfnl_acct_fill_info(skb2, NETLINK_CB(skb).portid,
 201                                          nlh->nlmsg_seq,
 202                                          NFNL_MSG_TYPE(nlh->nlmsg_type),
 203                                          NFNL_MSG_ACCT_NEW, cur);
 204                 if (ret <= 0) {
 205                         kfree_skb(skb2);
 206                         break;
 207                 }
 208                 ret = netlink_unicast(nfnl, skb2, NETLINK_CB(skb).portid,
 209                                         MSG_DONTWAIT);
 210                 if (ret > 0)
 211                         ret = 0;
 212
 213                 /* this avoids a loop in nfnetlink. */
 214                 return ret == -EAGAIN ? -ENOBUFS : ret;
 215         }
 216         return ret;
 217 }
 218
 219 /* try to delete object, fail if it is still in use. */
 220 static int nfnl_acct_try_del(struct nf_acct *cur)
 221 {
 222         int ret = 0;
 223
 224         /* we want to avoid races with nfnl_acct_find_get. */
 225         if (atomic_dec_and_test(&cur->refcnt)) {
 226                 /* We are protected by nfnl mutex. */
 227                 list_del_rcu(&cur->head);
 228                 kfree_rcu(cur, rcu_head);
 229         } else {
 230                 /* still in use, restore reference counter. */
 231                 atomic_inc(&cur->refcnt);
 232                 ret = -EBUSY;
 233         }
 234         return ret;
 235 }
 236
 237 static int
 238 nfnl_acct_del(struct sock *nfnl, struct sk_buff *skb,
 239              const struct nlmsghdr *nlh, const struct nlattr * const tb[])
 240 {
 241         char *acct_name;
 242         struct nf_acct *cur;
 243         int ret = -ENOENT;
 244
 245         if (!tb[NFACCT_NAME]) {
 246                 list_for_each_entry(cur, &nfnl_acct_list, head)
 247                         nfnl_acct_try_del(cur);
 248
 249                 return 0;
 250         }
 251         acct_name = nla_data(tb[NFACCT_NAME]);
 252
 253         list_for_each_entry(cur, &nfnl_acct_list, head) {
 254                 if (strncmp(cur->name, acct_name, NFACCT_NAME_MAX) != 0)
 255                         continue;
 256
 257                 ret = nfnl_acct_try_del(cur);
 258                 if (ret < 0)
 259                         return ret;
 260
 261                 break;
 262         }
 263         return ret;
 264 }
 265
 266 static const struct nla_policy nfnl_acct_policy[NFACCT_MAX+1] = {
 267         [NFACCT_NAME] = { .type = NLA_NUL_STRING, .len = NFACCT_NAME_MAX-1 },
 268         [NFACCT_BYTES] = { .type = NLA_U64 },
 269         [NFACCT_PKTS] = { .type = NLA_U64 },
 270 };
 271
 272 static const struct nfnl_callback nfnl_acct_cb[NFNL_MSG_ACCT_MAX] = {
 273         [NFNL_MSG_ACCT_NEW]             = { .call = nfnl_acct_new,
 274                                             .attr_count = NFACCT_MAX,
 275                                             .policy = nfnl_acct_policy },
 276         [NFNL_MSG_ACCT_GET]             = { .call = nfnl_acct_get,
 277                                             .attr_count = NFACCT_MAX,
 278                                             .policy = nfnl_acct_policy },
 279         [NFNL_MSG_ACCT_GET_CTRZERO]     = { .call = nfnl_acct_get,
 280                                             .attr_count = NFACCT_MAX,
 281                                             .policy = nfnl_acct_policy },
 282         [NFNL_MSG_ACCT_DEL]             = { .call = nfnl_acct_del,
 283                                             .attr_count = NFACCT_MAX,
 284                                             .policy = nfnl_acct_policy },
 285 };
 286
 287 static const struct nfnetlink_subsystem nfnl_acct_subsys = {
 288         .name                           = "acct",
 289         .subsys_id                      = NFNL_SUBSYS_ACCT,
 290         .cb_count                       = NFNL_MSG_ACCT_MAX,
 291         .cb                             = nfnl_acct_cb,
 292 };
 293
 294 MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_ACCT);
 295
 296 struct nf_acct *nfnl_acct_find_get(const char *acct_name)
 297 {
 298         struct nf_acct *cur, *acct = NULL;
 299
 300         rcu_read_lock();
 301         list_for_each_entry_rcu(cur, &nfnl_acct_list, head) {
 302                 if (strncmp(cur->name, acct_name, NFACCT_NAME_MAX)!= 0)
 303                         continue;
 304
 305                 if (!try_module_get(THIS_MODULE))
 306                         goto err;
 307
 308                 if (!atomic_inc_not_zero(&cur->refcnt)) {
 309                         module_put(THIS_MODULE);
 310                         goto err;
 311                 }
 312
 313                 acct = cur;
 314                 break;
 315         }
 316 err:
 317         rcu_read_unlock();
 318         return acct;
 319 }
 320 EXPORT_SYMBOL_GPL(nfnl_acct_find_get);
 321
 322 void nfnl_acct_put(struct nf_acct *acct)
 323 {
 324         atomic_dec(&acct->refcnt);
 325         module_put(THIS_MODULE);
 326 }
 327 EXPORT_SYMBOL_GPL(nfnl_acct_put);
 328
 329 void nfnl_acct_update(const struct sk_buff *skb, struct nf_acct *nfacct)
 330 {
 331         atomic64_inc(&nfacct->pkts);
 332         atomic64_add(skb->len, &nfacct->bytes);
 333 }
 334 EXPORT_SYMBOL_GPL(nfnl_acct_update);
 335
 336 static int __init nfnl_acct_init(void)
 337 {
 338         int ret;
 339
 340         pr_info("nfnl_acct: registering with nfnetlink.\n");
 341         ret = nfnetlink_subsys_register(&nfnl_acct_subsys);
 342         if (ret < 0) {
 343                 pr_err("nfnl_acct_init: cannot register with nfnetlink.\n");
 344                 goto err_out;
 345         }
 346         return 0;
 347 err_out:
 348         return ret;
 349 }
 350
 351 static void __exit nfnl_acct_exit(void)
 352 {
 353         struct nf_acct *cur, *tmp;
 354
 355         pr_info("nfnl_acct: unregistering from nfnetlink.\n");
 356         nfnetlink_subsys_unregister(&nfnl_acct_subsys);
 357
 358         list_for_each_entry_safe(cur, tmp, &nfnl_acct_list, head) {
 359                 list_del_rcu(&cur->head);
 360                 /* We are sure that our objects have no clients at this point,
 361                  * it's safe to release them all without checking refcnt. */
 362                 kfree_rcu(cur, rcu_head);
 363         }
 364 }
 365
 366 module_init(nfnl_acct_init);
 367 module_exit(nfnl_acct_exit);