linux/net/netfilter/nfnetlink_acct.c
<<
>>
Prefs
   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
  26MODULE_LICENSE("GPL");
  27MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
  28MODULE_DESCRIPTION("nfacct: Extended Netfilter accounting infrastructure");
  29
  30static LIST_HEAD(nfnl_acct_list);
  31
  32struct 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
  41static int
  42nfnl_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
  95static int
  96nfnl_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
 132nlmsg_failure:
 133nla_put_failure:
 134        nlmsg_cancel(skb, nlh);
 135        return -1;
 136}
 137
 138static int
 139nfnl_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) {
 153                        if (cur != last)
 154                                continue;
 155
 156                        last = NULL;
 157                }
 158                if (nfnl_acct_fill_info(skb, NETLINK_CB(cb->skb).portid,
 159                                       cb->nlh->nlmsg_seq,
 160                                       NFNL_MSG_TYPE(cb->nlh->nlmsg_type),
 161                                       NFNL_MSG_ACCT_NEW, cur) < 0) {
 162                        cb->args[1] = (unsigned long)cur;
 163                        break;
 164                }
 165        }
 166        if (!cb->args[1])
 167                cb->args[2] = 1;
 168        rcu_read_unlock();
 169        return skb->len;
 170}
 171
 172static int
 173nfnl_acct_get(struct sock *nfnl, struct sk_buff *skb,
 174             const struct nlmsghdr *nlh, const struct nlattr * const tb[])
 175{
 176        int ret = -ENOENT;
 177        struct nf_acct *cur;
 178        char *acct_name;
 179
 180        if (nlh->nlmsg_flags & NLM_F_DUMP) {
 181                struct netlink_dump_control c = {
 182                        .dump = nfnl_acct_dump,
 183                };
 184                return netlink_dump_start(nfnl, skb, nlh, &c);
 185        }
 186
 187        if (!tb[NFACCT_NAME])
 188                return -EINVAL;
 189        acct_name = nla_data(tb[NFACCT_NAME]);
 190
 191        list_for_each_entry(cur, &nfnl_acct_list, head) {
 192                struct sk_buff *skb2;
 193
 194                if (strncmp(cur->name, acct_name, NFACCT_NAME_MAX)!= 0)
 195                        continue;
 196
 197                skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 198                if (skb2 == NULL) {
 199                        ret = -ENOMEM;
 200                        break;
 201                }
 202
 203                ret = nfnl_acct_fill_info(skb2, NETLINK_CB(skb).portid,
 204                                         nlh->nlmsg_seq,
 205                                         NFNL_MSG_TYPE(nlh->nlmsg_type),
 206                                         NFNL_MSG_ACCT_NEW, cur);
 207                if (ret <= 0) {
 208                        kfree_skb(skb2);
 209                        break;
 210                }
 211                ret = netlink_unicast(nfnl, skb2, NETLINK_CB(skb).portid,
 212                                        MSG_DONTWAIT);
 213                if (ret > 0)
 214                        ret = 0;
 215
 216                /* this avoids a loop in nfnetlink. */
 217                return ret == -EAGAIN ? -ENOBUFS : ret;
 218        }
 219        return ret;
 220}
 221
 222/* try to delete object, fail if it is still in use. */
 223static int nfnl_acct_try_del(struct nf_acct *cur)
 224{
 225        int ret = 0;
 226
 227        /* we want to avoid races with nfnl_acct_find_get. */
 228        if (atomic_dec_and_test(&cur->refcnt)) {
 229                /* We are protected by nfnl mutex. */
 230                list_del_rcu(&cur->head);
 231                kfree_rcu(cur, rcu_head);
 232        } else {
 233                /* still in use, restore reference counter. */
 234                atomic_inc(&cur->refcnt);
 235                ret = -EBUSY;
 236        }
 237        return ret;
 238}
 239
 240static int
 241nfnl_acct_del(struct sock *nfnl, struct sk_buff *skb,
 242             const struct nlmsghdr *nlh, const struct nlattr * const tb[])
 243{
 244        char *acct_name;
 245        struct nf_acct *cur;
 246        int ret = -ENOENT;
 247
 248        if (!tb[NFACCT_NAME]) {
 249                list_for_each_entry(cur, &nfnl_acct_list, head)
 250                        nfnl_acct_try_del(cur);
 251
 252                return 0;
 253        }
 254        acct_name = nla_data(tb[NFACCT_NAME]);
 255
 256        list_for_each_entry(cur, &nfnl_acct_list, head) {
 257                if (strncmp(cur->name, acct_name, NFACCT_NAME_MAX) != 0)
 258                        continue;
 259
 260                ret = nfnl_acct_try_del(cur);
 261                if (ret < 0)
 262                        return ret;
 263
 264                break;
 265        }
 266        return ret;
 267}
 268
 269static const struct nla_policy nfnl_acct_policy[NFACCT_MAX+1] = {
 270        [NFACCT_NAME] = { .type = NLA_NUL_STRING, .len = NFACCT_NAME_MAX-1 },
 271        [NFACCT_BYTES] = { .type = NLA_U64 },
 272        [NFACCT_PKTS] = { .type = NLA_U64 },
 273};
 274
 275static const struct nfnl_callback nfnl_acct_cb[NFNL_MSG_ACCT_MAX] = {
 276        [NFNL_MSG_ACCT_NEW]             = { .call = nfnl_acct_new,
 277                                            .attr_count = NFACCT_MAX,
 278                                            .policy = nfnl_acct_policy },
 279        [NFNL_MSG_ACCT_GET]             = { .call = nfnl_acct_get,
 280                                            .attr_count = NFACCT_MAX,
 281                                            .policy = nfnl_acct_policy },
 282        [NFNL_MSG_ACCT_GET_CTRZERO]     = { .call = nfnl_acct_get,
 283                                            .attr_count = NFACCT_MAX,
 284                                            .policy = nfnl_acct_policy },
 285        [NFNL_MSG_ACCT_DEL]             = { .call = nfnl_acct_del,
 286                                            .attr_count = NFACCT_MAX,
 287                                            .policy = nfnl_acct_policy },
 288};
 289
 290static const struct nfnetlink_subsystem nfnl_acct_subsys = {
 291        .name                           = "acct",
 292        .subsys_id                      = NFNL_SUBSYS_ACCT,
 293        .cb_count                       = NFNL_MSG_ACCT_MAX,
 294        .cb                             = nfnl_acct_cb,
 295};
 296
 297MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_ACCT);
 298
 299struct nf_acct *nfnl_acct_find_get(const char *acct_name)
 300{
 301        struct nf_acct *cur, *acct = NULL;
 302
 303        rcu_read_lock();
 304        list_for_each_entry_rcu(cur, &nfnl_acct_list, head) {
 305                if (strncmp(cur->name, acct_name, NFACCT_NAME_MAX)!= 0)
 306                        continue;
 307
 308                if (!try_module_get(THIS_MODULE))
 309                        goto err;
 310
 311                if (!atomic_inc_not_zero(&cur->refcnt)) {
 312                        module_put(THIS_MODULE);
 313                        goto err;
 314                }
 315
 316                acct = cur;
 317                break;
 318        }
 319err:
 320        rcu_read_unlock();
 321        return acct;
 322}
 323EXPORT_SYMBOL_GPL(nfnl_acct_find_get);
 324
 325void nfnl_acct_put(struct nf_acct *acct)
 326{
 327        atomic_dec(&acct->refcnt);
 328        module_put(THIS_MODULE);
 329}
 330EXPORT_SYMBOL_GPL(nfnl_acct_put);
 331
 332void nfnl_acct_update(const struct sk_buff *skb, struct nf_acct *nfacct)
 333{
 334        atomic64_inc(&nfacct->pkts);
 335        atomic64_add(skb->len, &nfacct->bytes);
 336}
 337EXPORT_SYMBOL_GPL(nfnl_acct_update);
 338
 339static int __init nfnl_acct_init(void)
 340{
 341        int ret;
 342
 343        pr_info("nfnl_acct: registering with nfnetlink.\n");
 344        ret = nfnetlink_subsys_register(&nfnl_acct_subsys);
 345        if (ret < 0) {
 346                pr_err("nfnl_acct_init: cannot register with nfnetlink.\n");
 347                goto err_out;
 348        }
 349        return 0;
 350err_out:
 351        return ret;
 352}
 353
 354static void __exit nfnl_acct_exit(void)
 355{
 356        struct nf_acct *cur, *tmp;
 357
 358        pr_info("nfnl_acct: unregistering from nfnetlink.\n");
 359        nfnetlink_subsys_unregister(&nfnl_acct_subsys);
 360
 361        list_for_each_entry_safe(cur, tmp, &nfnl_acct_list, head) {
 362                list_del_rcu(&cur->head);
 363                /* We are sure that our objects have no clients at this point,
 364                 * it's safe to release them all without checking refcnt. */
 365                kfree_rcu(cur, rcu_head);
 366        }
 367}
 368
 369module_init(nfnl_acct_init);
 370module_exit(nfnl_acct_exit);
 371
lxr.linux.no kindly hosted by Redpill Linpro AS, provider of Linux consulting and operations services since 1995.