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/netlink.h>
  14 #include <linux/rculist.h>
  15 #include <linux/slab.h>
  16 #include <linux/types.h>
  17 #include <linux/errno.h>
  18 #include <net/netlink.h>
  19 #include <net/sock.h>
  20 #include <asm/atomic.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
  53         list_for_each_entry(nfacct, &nfnl_acct_list, head) {
  54                 if (strncmp(nfacct->name, acct_name, NFACCT_NAME_MAX) != 0)
  55                         continue;
  56
  57                 if (nlh->nlmsg_flags & NLM_F_EXCL)
  58                         return -EEXIST;
  59
  60                 matching = nfacct;
  61                 break;
  62         }
  63
  64         if (matching) {
  65                 if (nlh->nlmsg_flags & NLM_F_REPLACE) {
  66                         /* reset counters if you request a replacement. */
  67                         atomic64_set(&matching->pkts, 0);
  68                         atomic64_set(&matching->bytes, 0);
  69                         return 0;
  70                 }
  71                 return -EBUSY;
  72         }
  73
  74         nfacct = kzalloc(sizeof(struct nf_acct), GFP_KERNEL);
  75         if (nfacct == NULL)
  76                 return -ENOMEM;
  77
  78         strncpy(nfacct->name, nla_data(tb[NFACCT_NAME]), NFACCT_NAME_MAX);
  79
  80         if (tb[NFACCT_BYTES]) {
  81                 atomic64_set(&nfacct->bytes,
  82                              be64_to_cpu(nla_get_u64(tb[NFACCT_BYTES])));
  83         }
  84         if (tb[NFACCT_PKTS]) {
  85                 atomic64_set(&nfacct->pkts,
  86                              be64_to_cpu(nla_get_u64(tb[NFACCT_PKTS])));
  87         }
  88         atomic_set(&nfacct->refcnt, 1);
  89         list_add_tail_rcu(&nfacct->head, &nfnl_acct_list);
  90         return 0;
  91 }
  92
  93 static int
  94 nfnl_acct_fill_info(struct sk_buff *skb, u32 pid, u32 seq, u32 type,
  95                    int event, struct nf_acct *acct)
  96 {
  97         struct nlmsghdr *nlh;
  98         struct nfgenmsg *nfmsg;
  99         unsigned int flags = pid ? NLM_F_MULTI : 0;
 100         u64 pkts, bytes;
 101
 102         event |= NFNL_SUBSYS_ACCT << 8;
 103         nlh = nlmsg_put(skb, pid, seq, event, sizeof(*nfmsg), flags);
 104         if (nlh == NULL)
 105                 goto nlmsg_failure;
 106
 107         nfmsg = nlmsg_data(nlh);
 108         nfmsg->nfgen_family = AF_UNSPEC;
 109         nfmsg->version = NFNETLINK_V0;
 110         nfmsg->res_id = 0;
 111
 112         NLA_PUT_STRING(skb, NFACCT_NAME, acct->name);
 113
 114         if (type == NFNL_MSG_ACCT_GET_CTRZERO) {
 115                 pkts = atomic64_xchg(&acct->pkts, 0);
 116                 bytes = atomic64_xchg(&acct->bytes, 0);
 117         } else {
 118                 pkts = atomic64_read(&acct->pkts);
 119                 bytes = atomic64_read(&acct->bytes);
 120         }
 121         NLA_PUT_BE64(skb, NFACCT_PKTS, cpu_to_be64(pkts));
 122         NLA_PUT_BE64(skb, NFACCT_BYTES, cpu_to_be64(bytes));
 123         NLA_PUT_BE32(skb, NFACCT_USE, htonl(atomic_read(&acct->refcnt)));
 124
 125         nlmsg_end(skb, nlh);
 126         return skb->len;
 127
 128 nlmsg_failure:
 129 nla_put_failure:
 130         nlmsg_cancel(skb, nlh);
 131         return -1;
 132 }
 133
 134 static int
 135 nfnl_acct_dump(struct sk_buff *skb, struct netlink_callback *cb)
 136 {
 137         struct nf_acct *cur, *last;
 138
 139         if (cb->args[2])
 140                 return 0;
 141
 142         last = (struct nf_acct *)cb->args[1];
 143         if (cb->args[1])
 144                 cb->args[1] = 0;
 145
 146         rcu_read_lock();
 147         list_for_each_entry_rcu(cur, &nfnl_acct_list, head) {
 148                 if (last && cur != last)
 149                         continue;
 150
 151                 if (nfnl_acct_fill_info(skb, NETLINK_CB(cb->skb).pid,
 152                                        cb->nlh->nlmsg_seq,
 153                                        NFNL_MSG_TYPE(cb->nlh->nlmsg_type),
 154                                        NFNL_MSG_ACCT_NEW, cur) < 0) {
 155                         cb->args[1] = (unsigned long)cur;
 156                         break;
 157                 }
 158         }
 159         if (!cb->args[1])
 160                 cb->args[2] = 1;
 161         rcu_read_unlock();
 162         return skb->len;
 163 }
 164
 165 static int
 166 nfnl_acct_get(struct sock *nfnl, struct sk_buff *skb,
 167              const struct nlmsghdr *nlh, const struct nlattr * const tb[])
 168 {
 169         int ret = -ENOENT;
 170         struct nf_acct *cur;
 171         char *acct_name;
 172
 173         if (nlh->nlmsg_flags & NLM_F_DUMP) {
 174                 struct netlink_dump_control c = {
 175                         .dump = nfnl_acct_dump,
 176                 };
 177                 return netlink_dump_start(nfnl, skb, nlh, &c);
 178         }
 179
 180         if (!tb[NFACCT_NAME])
 181                 return -EINVAL;
 182         acct_name = nla_data(tb[NFACCT_NAME]);
 183
 184         list_for_each_entry(cur, &nfnl_acct_list, head) {
 185                 struct sk_buff *skb2;
 186
 187                 if (strncmp(cur->name, acct_name, NFACCT_NAME_MAX)!= 0)
 188                         continue;
 189
 190                 skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 191                 if (skb2 == NULL) {
 192                         ret = -ENOMEM;
 193                         break;
 194                 }
 195
 196                 ret = nfnl_acct_fill_info(skb2, NETLINK_CB(skb).pid,
 197                                          nlh->nlmsg_seq,
 198                                          NFNL_MSG_TYPE(nlh->nlmsg_type),
 199                                          NFNL_MSG_ACCT_NEW, cur);
 200                 if (ret <= 0) {
 201                         kfree_skb(skb2);
 202                         break;
 203                 }
 204                 ret = netlink_unicast(nfnl, skb2, NETLINK_CB(skb).pid,
 205                                         MSG_DONTWAIT);
 206                 if (ret > 0)
 207                         ret = 0;
 208
 209                 /* this avoids a loop in nfnetlink. */
 210                 return ret == -EAGAIN ? -ENOBUFS : ret;
 211         }
 212         return ret;
 213 }
 214
 215 /* try to delete object, fail if it is still in use. */
 216 static int nfnl_acct_try_del(struct nf_acct *cur)
 217 {
 218         int ret = 0;
 219
 220         /* we want to avoid races with nfnl_acct_find_get. */
 221         if (atomic_dec_and_test(&cur->refcnt)) {
 222                 /* We are protected by nfnl mutex. */
 223                 list_del_rcu(&cur->head);
 224                 kfree_rcu(cur, rcu_head);
 225         } else {
 226                 /* still in use, restore reference counter. */
 227                 atomic_inc(&cur->refcnt);
 228                 ret = -EBUSY;
 229         }
 230         return ret;
 231 }
 232
 233 static int
 234 nfnl_acct_del(struct sock *nfnl, struct sk_buff *skb,
 235              const struct nlmsghdr *nlh, const struct nlattr * const tb[])
 236 {
 237         char *acct_name;
 238         struct nf_acct *cur;
 239         int ret = -ENOENT;
 240
 241         if (!tb[NFACCT_NAME]) {
 242                 list_for_each_entry(cur, &nfnl_acct_list, head)
 243                         nfnl_acct_try_del(cur);
 244
 245                 return 0;
 246         }
 247         acct_name = nla_data(tb[NFACCT_NAME]);
 248
 249         list_for_each_entry(cur, &nfnl_acct_list, head) {
 250                 if (strncmp(cur->name, acct_name, NFACCT_NAME_MAX) != 0)
 251                         continue;
 252
 253                 ret = nfnl_acct_try_del(cur);
 254                 if (ret < 0)
 255                         return ret;
 256
 257                 break;
 258         }
 259         return ret;
 260 }
 261
 262 static const struct nla_policy nfnl_acct_policy[NFACCT_MAX+1] = {
 263         [NFACCT_NAME] = { .type = NLA_NUL_STRING, .len = NFACCT_NAME_MAX-1 },
 264         [NFACCT_BYTES] = { .type = NLA_U64 },
 265         [NFACCT_PKTS] = { .type = NLA_U64 },
 266 };
 267
 268 static const struct nfnl_callback nfnl_acct_cb[NFNL_MSG_ACCT_MAX] = {
 269         [NFNL_MSG_ACCT_NEW]             = { .call = nfnl_acct_new,
 270                                             .attr_count = NFACCT_MAX,
 271                                             .policy = nfnl_acct_policy },
 272         [NFNL_MSG_ACCT_GET]             = { .call = nfnl_acct_get,
 273                                             .attr_count = NFACCT_MAX,
 274                                             .policy = nfnl_acct_policy },
 275         [NFNL_MSG_ACCT_GET_CTRZERO]     = { .call = nfnl_acct_get,
 276                                             .attr_count = NFACCT_MAX,
 277                                             .policy = nfnl_acct_policy },
 278         [NFNL_MSG_ACCT_DEL]             = { .call = nfnl_acct_del,
 279                                             .attr_count = NFACCT_MAX,
 280                                             .policy = nfnl_acct_policy },
 281 };
 282
 283 static const struct nfnetlink_subsystem nfnl_acct_subsys = {
 284         .name                           = "acct",
 285         .subsys_id                      = NFNL_SUBSYS_ACCT,
 286         .cb_count                       = NFNL_MSG_ACCT_MAX,
 287         .cb                             = nfnl_acct_cb,
 288 };
 289
 290 MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_ACCT);
 291
 292 struct nf_acct *nfnl_acct_find_get(const char *acct_name)
 293 {
 294         struct nf_acct *cur, *acct = NULL;
 295
 296         rcu_read_lock();
 297         list_for_each_entry_rcu(cur, &nfnl_acct_list, head) {
 298                 if (strncmp(cur->name, acct_name, NFACCT_NAME_MAX)!= 0)
 299                         continue;
 300
 301                 if (!try_module_get(THIS_MODULE))
 302                         goto err;
 303
 304                 if (!atomic_inc_not_zero(&cur->refcnt)) {
 305                         module_put(THIS_MODULE);
 306                         goto err;
 307                 }
 308
 309                 acct = cur;
 310                 break;
 311         }
 312 err:
 313         rcu_read_unlock();
 314         return acct;
 315 }
 316 EXPORT_SYMBOL_GPL(nfnl_acct_find_get);
 317
 318 void nfnl_acct_put(struct nf_acct *acct)
 319 {
 320         atomic_dec(&acct->refcnt);
 321         module_put(THIS_MODULE);
 322 }
 323 EXPORT_SYMBOL_GPL(nfnl_acct_put);
 324
 325 void nfnl_acct_update(const struct sk_buff *skb, struct nf_acct *nfacct)
 326 {
 327         atomic64_inc(&nfacct->pkts);
 328         atomic64_add(skb->len, &nfacct->bytes);
 329 }
 330 EXPORT_SYMBOL_GPL(nfnl_acct_update);
 331
 332 static int __init nfnl_acct_init(void)
 333 {
 334         int ret;
 335
 336         pr_info("nfnl_acct: registering with nfnetlink.\n");
 337         ret = nfnetlink_subsys_register(&nfnl_acct_subsys);
 338         if (ret < 0) {
 339                 pr_err("nfnl_acct_init: cannot register with nfnetlink.\n");
 340                 goto err_out;
 341         }
 342         return 0;
 343 err_out:
 344         return ret;
 345 }
 346
 347 static void __exit nfnl_acct_exit(void)
 348 {
 349         struct nf_acct *cur, *tmp;
 350
 351         pr_info("nfnl_acct: unregistering from nfnetlink.\n");
 352         nfnetlink_subsys_unregister(&nfnl_acct_subsys);
 353
 354         list_for_each_entry_safe(cur, tmp, &nfnl_acct_list, head) {
 355                 list_del_rcu(&cur->head);
 356                 /* We are sure that our objects have no clients at this point,
 357                  * it's safe to release them all without checking refcnt. */
 358                 kfree_rcu(cur, rcu_head);
 359         }
 360 }
 361
 362 module_init(nfnl_acct_init);
 363 module_exit(nfnl_acct_exit);