net/ipv4/netfilter/ip_queue.c

   1 /*
   2  * This is a module which is used for queueing IPv4 packets and
   3  * communicating with userspace via netlink.
   4  *
   5  * (C) 2000-2002 James Morris <jmorris@intercode.com.au>
   6  * (C) 2003-2005 Netfilter Core Team <coreteam@netfilter.org>
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  */
  12 #include <linux/module.h>
  13 #include <linux/skbuff.h>
  14 #include <linux/init.h>
  15 #include <linux/ip.h>
  16 #include <linux/notifier.h>
  17 #include <linux/netdevice.h>
  18 #include <linux/netfilter.h>
  19 #include <linux/netfilter_ipv4/ip_queue.h>
  20 #include <linux/netfilter_ipv4/ip_tables.h>
  21 #include <linux/netlink.h>
  22 #include <linux/spinlock.h>
  23 #include <linux/sysctl.h>
  24 #include <linux/proc_fs.h>
  25 #include <linux/seq_file.h>
  26 #include <linux/security.h>
  27 #include <linux/mutex.h>
  28 #include <net/net_namespace.h>
  29 #include <net/sock.h>
  30 #include <net/route.h>
  31 #include <net/netfilter/nf_queue.h>
  32 #include <net/ip.h>
  33
  34 #define IPQ_QMAX_DEFAULT 1024
  35 #define IPQ_PROC_FS_NAME "ip_queue"
  36 #define NET_IPQ_QMAX 2088
  37 #define NET_IPQ_QMAX_NAME "ip_queue_maxlen"
  38
  39 typedef int (*ipq_cmpfn)(struct nf_queue_entry *, unsigned long);
  40
  41 static unsigned char copy_mode __read_mostly = IPQ_COPY_NONE;
  42 static unsigned int queue_maxlen __read_mostly = IPQ_QMAX_DEFAULT;
  43 static DEFINE_RWLOCK(queue_lock);
  44 static int peer_pid __read_mostly;
  45 static unsigned int copy_range __read_mostly;
  46 static unsigned int queue_total;
  47 static unsigned int queue_dropped = 0;
  48 static unsigned int queue_user_dropped = 0;
  49 static struct sock *ipqnl __read_mostly;
  50 static LIST_HEAD(queue_list);
  51 static DEFINE_MUTEX(ipqnl_mutex);
  52
  53 static inline void
  54 __ipq_enqueue_entry(struct nf_queue_entry *entry)
  55 {
  56        list_add_tail(&entry->list, &queue_list);
  57        queue_total++;
  58 }
  59
  60 static inline int
  61 __ipq_set_mode(unsigned char mode, unsigned int range)
  62 {
  63         int status = 0;
  64
  65         switch(mode) {
  66         case IPQ_COPY_NONE:
  67         case IPQ_COPY_META:
  68                 copy_mode = mode;
  69                 copy_range = 0;
  70                 break;
  71
  72         case IPQ_COPY_PACKET:
  73                 copy_mode = mode;
  74                 copy_range = range;
  75                 if (copy_range > 0xFFFF)
  76                         copy_range = 0xFFFF;
  77                 break;
  78
  79         default:
  80                 status = -EINVAL;
  81
  82         }
  83         return status;
  84 }
  85
  86 static void __ipq_flush(ipq_cmpfn cmpfn, unsigned long data);
  87
  88 static inline void
  89 __ipq_reset(void)
  90 {
  91         peer_pid = 0;
  92         net_disable_timestamp();
  93         __ipq_set_mode(IPQ_COPY_NONE, 0);
  94         __ipq_flush(NULL, 0);
  95 }
  96
  97 static struct nf_queue_entry *
  98 ipq_find_dequeue_entry(unsigned long id)
  99 {
 100         struct nf_queue_entry *entry = NULL, *i;
 101
 102         write_lock_bh(&queue_lock);
 103
 104         list_for_each_entry(i, &queue_list, list) {
 105                 if ((unsigned long)i == id) {
 106                         entry = i;
 107                         break;
 108                 }
 109         }
 110
 111         if (entry) {
 112                 list_del(&entry->list);
 113                 queue_total--;
 114         }
 115
 116         write_unlock_bh(&queue_lock);
 117         return entry;
 118 }
 119
 120 static void
 121 __ipq_flush(ipq_cmpfn cmpfn, unsigned long data)
 122 {
 123         struct nf_queue_entry *entry, *next;
 124
 125         list_for_each_entry_safe(entry, next, &queue_list, list) {
 126                 if (!cmpfn || cmpfn(entry, data)) {
 127                         list_del(&entry->list);
 128                         queue_total--;
 129                         nf_reinject(entry, NF_DROP);
 130                 }
 131         }
 132 }
 133
 134 static void
 135 ipq_flush(ipq_cmpfn cmpfn, unsigned long data)
 136 {
 137         write_lock_bh(&queue_lock);
 138         __ipq_flush(cmpfn, data);
 139         write_unlock_bh(&queue_lock);
 140 }
 141
 142 static struct sk_buff *
 143 ipq_build_packet_message(struct nf_queue_entry *entry, int *errp)
 144 {
 145         sk_buff_data_t old_tail;
 146         size_t size = 0;
 147         size_t data_len = 0;
 148         struct sk_buff *skb;
 149         struct ipq_packet_msg *pmsg;
 150         struct nlmsghdr *nlh;
 151         struct timeval tv;
 152
 153         read_lock_bh(&queue_lock);
 154
 155         switch (copy_mode) {
 156         case IPQ_COPY_META:
 157         case IPQ_COPY_NONE:
 158                 size = NLMSG_SPACE(sizeof(*pmsg));
 159                 data_len = 0;
 160                 break;
 161
 162         case IPQ_COPY_PACKET:
 163                 if ((entry->skb->ip_summed == CHECKSUM_PARTIAL ||
 164                      entry->skb->ip_summed == CHECKSUM_COMPLETE) &&
 165                     (*errp = skb_checksum_help(entry->skb))) {
 166                         read_unlock_bh(&queue_lock);
 167                         return NULL;
 168                 }
 169                 if (copy_range == 0 || copy_range > entry->skb->len)
 170                         data_len = entry->skb->len;
 171                 else
 172                         data_len = copy_range;
 173
 174                 size = NLMSG_SPACE(sizeof(*pmsg) + data_len);
 175                 break;
 176
 177         default:
 178                 *errp = -EINVAL;
 179                 read_unlock_bh(&queue_lock);
 180                 return NULL;
 181         }
 182
 183         read_unlock_bh(&queue_lock);
 184
 185         skb = alloc_skb(size, GFP_ATOMIC);
 186         if (!skb)
 187                 goto nlmsg_failure;
 188
 189         old_tail = skb->tail;
 190         nlh = NLMSG_PUT(skb, 0, 0, IPQM_PACKET, size - sizeof(*nlh));
 191         pmsg = NLMSG_DATA(nlh);
 192         memset(pmsg, 0, sizeof(*pmsg));
 193
 194         pmsg->packet_id       = (unsigned long )entry;
 195         pmsg->data_len        = data_len;
 196         tv = ktime_to_timeval(entry->skb->tstamp);
 197         pmsg->timestamp_sec   = tv.tv_sec;
 198         pmsg->timestamp_usec  = tv.tv_usec;
 199         pmsg->mark            = entry->skb->mark;
 200         pmsg->hook            = entry->hook;
 201         pmsg->hw_protocol     = entry->skb->protocol;
 202
 203         if (entry->indev)
 204                 strcpy(pmsg->indev_name, entry->indev->name);
 205         else
 206                 pmsg->indev_name[0] = '\0';
 207
 208         if (entry->outdev)
 209                 strcpy(pmsg->outdev_name, entry->outdev->name);
 210         else
 211                 pmsg->outdev_name[0] = '\0';
 212
 213         if (entry->indev && entry->skb->dev) {
 214                 pmsg->hw_type = entry->skb->dev->type;
 215                 pmsg->hw_addrlen = dev_parse_header(entry->skb,
 216                                                     pmsg->hw_addr);
 217         }
 218
 219         if (data_len)
 220                 if (skb_copy_bits(entry->skb, 0, pmsg->payload, data_len))
 221                         BUG();
 222
 223         nlh->nlmsg_len = skb->tail - old_tail;
 224         return skb;
 225
 226 nlmsg_failure:
 227         if (skb)
 228                 kfree_skb(skb);
 229         *errp = -EINVAL;
 230         printk(KERN_ERR "ip_queue: error creating packet message\n");
 231         return NULL;
 232 }
 233
 234 static int
 235 ipq_enqueue_packet(struct nf_queue_entry *entry, unsigned int queuenum)
 236 {
 237         int status = -EINVAL;
 238         struct sk_buff *nskb;
 239
 240         if (copy_mode == IPQ_COPY_NONE)
 241                 return -EAGAIN;
 242
 243         nskb = ipq_build_packet_message(entry, &status);
 244         if (nskb == NULL)
 245                 return status;
 246
 247         write_lock_bh(&queue_lock);
 248
 249         if (!peer_pid)
 250                 goto err_out_free_nskb;
 251
 252         if (queue_total >= queue_maxlen) {
 253                 queue_dropped++;
 254                 status = -ENOSPC;
 255                 if (net_ratelimit())
 256                           printk (KERN_WARNING "ip_queue: full at %d entries, "
 257                                   "dropping packets(s). Dropped: %d\n", queue_total,
 258                                   queue_dropped);
 259                 goto err_out_free_nskb;
 260         }
 261
 262         /* netlink_unicast will either free the nskb or attach it to a socket */
 263         status = netlink_unicast(ipqnl, nskb, peer_pid, MSG_DONTWAIT);
 264         if (status < 0) {
 265                 queue_user_dropped++;
 266                 goto err_out_unlock;
 267         }
 268
 269         __ipq_enqueue_entry(entry);
 270
 271         write_unlock_bh(&queue_lock);
 272         return status;
 273
 274 err_out_free_nskb:
 275         kfree_skb(nskb);
 276
 277 err_out_unlock:
 278         write_unlock_bh(&queue_lock);
 279         return status;
 280 }
 281
 282 static int
 283 ipq_mangle_ipv4(ipq_verdict_msg_t *v, struct nf_queue_entry *e)
 284 {
 285         int diff;
 286         struct iphdr *user_iph = (struct iphdr *)v->payload;
 287         struct sk_buff *nskb;
 288
 289         if (v->data_len < sizeof(*user_iph))
 290                 return 0;
 291         diff = v->data_len - e->skb->len;
 292         if (diff < 0) {
 293                 if (pskb_trim(e->skb, v->data_len))
 294                         return -ENOMEM;
 295         } else if (diff > 0) {
 296                 if (v->data_len > 0xFFFF)
 297                         return -EINVAL;
 298                 if (diff > skb_tailroom(e->skb)) {
 299                         nskb = skb_copy_expand(e->skb, skb_headroom(e->skb),
 300                                                diff, GFP_ATOMIC);
 301                         if (!nskb) {
 302                                 printk(KERN_WARNING "ip_queue: error "
 303                                       "in mangle, dropping packet\n");
 304                                 return -ENOMEM;
 305                         }
 306                         kfree_skb(e->skb);
 307                         e->skb = nskb;
 308                 }
 309                 skb_put(e->skb, diff);
 310         }
 311         if (!skb_make_writable(e->skb, v->data_len))
 312                 return -ENOMEM;
 313         skb_copy_to_linear_data(e->skb, v->payload, v->data_len);
 314         e->skb->ip_summed = CHECKSUM_NONE;
 315
 316         return 0;
 317 }
 318
 319 static int
 320 ipq_set_verdict(struct ipq_verdict_msg *vmsg, unsigned int len)
 321 {
 322         struct nf_queue_entry *entry;
 323
 324         if (vmsg->value > NF_MAX_VERDICT)
 325                 return -EINVAL;
 326
 327         entry = ipq_find_dequeue_entry(vmsg->id);
 328         if (entry == NULL)
 329                 return -ENOENT;
 330         else {
 331                 int verdict = vmsg->value;
 332
 333                 if (vmsg->data_len && vmsg->data_len == len)
 334                         if (ipq_mangle_ipv4(vmsg, entry) < 0)
 335                                 verdict = NF_DROP;
 336
 337                 nf_reinject(entry, verdict);
 338                 return 0;
 339         }
 340 }
 341
 342 static int
 343 ipq_set_mode(unsigned char mode, unsigned int range)
 344 {
 345         int status;
 346
 347         write_lock_bh(&queue_lock);
 348         status = __ipq_set_mode(mode, range);
 349         write_unlock_bh(&queue_lock);
 350         return status;
 351 }
 352
 353 static int
 354 ipq_receive_peer(struct ipq_peer_msg *pmsg,
 355                  unsigned char type, unsigned int len)
 356 {
 357         int status = 0;
 358
 359         if (len < sizeof(*pmsg))
 360                 return -EINVAL;
 361
 362         switch (type) {
 363         case IPQM_MODE:
 364                 status = ipq_set_mode(pmsg->msg.mode.value,
 365                                       pmsg->msg.mode.range);
 366                 break;
 367
 368         case IPQM_VERDICT:
 369                 if (pmsg->msg.verdict.value > NF_MAX_VERDICT)
 370                         status = -EINVAL;
 371                 else
 372                         status = ipq_set_verdict(&pmsg->msg.verdict,
 373                                                  len - sizeof(*pmsg));
 374                         break;
 375         default:
 376                 status = -EINVAL;
 377         }
 378         return status;
 379 }
 380
 381 static int
 382 dev_cmp(struct nf_queue_entry *entry, unsigned long ifindex)
 383 {
 384         if (entry->indev)
 385                 if (entry->indev->ifindex == ifindex)
 386                         return 1;
 387         if (entry->outdev)
 388                 if (entry->outdev->ifindex == ifindex)
 389                         return 1;
 390 #ifdef CONFIG_BRIDGE_NETFILTER
 391         if (entry->skb->nf_bridge) {
 392                 if (entry->skb->nf_bridge->physindev &&
 393                     entry->skb->nf_bridge->physindev->ifindex == ifindex)
 394                         return 1;
 395                 if (entry->skb->nf_bridge->physoutdev &&
 396                     entry->skb->nf_bridge->physoutdev->ifindex == ifindex)
 397                         return 1;
 398         }
 399 #endif
 400         return 0;
 401 }
 402
 403 static void
 404 ipq_dev_drop(int ifindex)
 405 {
 406         ipq_flush(dev_cmp, ifindex);
 407 }
 408
 409 #define RCV_SKB_FAIL(err) do { netlink_ack(skb, nlh, (err)); return; } while (0)
 410
 411 static inline void
 412 __ipq_rcv_skb(struct sk_buff *skb)
 413 {
 414         int status, type, pid, flags, nlmsglen, skblen;
 415         struct nlmsghdr *nlh;
 416
 417         skblen = skb->len;
 418         if (skblen < sizeof(*nlh))
 419                 return;
 420
 421         nlh = nlmsg_hdr(skb);
 422         nlmsglen = nlh->nlmsg_len;
 423         if (nlmsglen < sizeof(*nlh) || skblen < nlmsglen)
 424                 return;
 425
 426         pid = nlh->nlmsg_pid;
 427         flags = nlh->nlmsg_flags;
 428
 429         if(pid <= 0 || !(flags & NLM_F_REQUEST) || flags & NLM_F_MULTI)
 430                 RCV_SKB_FAIL(-EINVAL);
 431
 432         if (flags & MSG_TRUNC)
 433                 RCV_SKB_FAIL(-ECOMM);
 434
 435         type = nlh->nlmsg_type;
 436         if (type < NLMSG_NOOP || type >= IPQM_MAX)
 437                 RCV_SKB_FAIL(-EINVAL);
 438
 439         if (type <= IPQM_BASE)
 440                 return;
 441
 442         if (security_netlink_recv(skb, CAP_NET_ADMIN))
 443                 RCV_SKB_FAIL(-EPERM);
 444
 445         write_lock_bh(&queue_lock);
 446
 447         if (peer_pid) {
 448                 if (peer_pid != pid) {
 449                         write_unlock_bh(&queue_lock);
 450                         RCV_SKB_FAIL(-EBUSY);
 451                 }
 452         } else {
 453                 net_enable_timestamp();
 454                 peer_pid = pid;
 455         }
 456
 457         write_unlock_bh(&queue_lock);
 458
 459         status = ipq_receive_peer(NLMSG_DATA(nlh), type,
 460                                   nlmsglen - NLMSG_LENGTH(0));
 461         if (status < 0)
 462                 RCV_SKB_FAIL(status);
 463
 464         if (flags & NLM_F_ACK)
 465                 netlink_ack(skb, nlh, 0);
 466         return;
 467 }
 468
 469 static void
 470 ipq_rcv_skb(struct sk_buff *skb)
 471 {
 472         mutex_lock(&ipqnl_mutex);
 473         __ipq_rcv_skb(skb);
 474         mutex_unlock(&ipqnl_mutex);
 475 }
 476
 477 static int
 478 ipq_rcv_dev_event(struct notifier_block *this,
 479                   unsigned long event, void *ptr)
 480 {
 481         struct net_device *dev = ptr;
 482
 483         if (dev_net(dev) != &init_net)
 484                 return NOTIFY_DONE;
 485
 486         /* Drop any packets associated with the downed device */
 487         if (event == NETDEV_DOWN)
 488                 ipq_dev_drop(dev->ifindex);
 489         return NOTIFY_DONE;
 490 }
 491
 492 static struct notifier_block ipq_dev_notifier = {
 493         .notifier_call  = ipq_rcv_dev_event,
 494 };
 495
 496 static int
 497 ipq_rcv_nl_event(struct notifier_block *this,
 498                  unsigned long event, void *ptr)
 499 {
 500         struct netlink_notify *n = ptr;
 501
 502         if (event == NETLINK_URELEASE &&
 503             n->protocol == NETLINK_FIREWALL && n->pid) {
 504                 write_lock_bh(&queue_lock);
 505                 if ((n->net == &init_net) && (n->pid == peer_pid))
 506                         __ipq_reset();
 507                 write_unlock_bh(&queue_lock);
 508         }
 509         return NOTIFY_DONE;
 510 }
 511
 512 static struct notifier_block ipq_nl_notifier = {
 513         .notifier_call  = ipq_rcv_nl_event,
 514 };
 515
 516 #ifdef CONFIG_SYSCTL
 517 static struct ctl_table_header *ipq_sysctl_header;
 518
 519 static ctl_table ipq_table[] = {
 520         {
 521                 .ctl_name       = NET_IPQ_QMAX,
 522                 .procname       = NET_IPQ_QMAX_NAME,
 523                 .data           = &queue_maxlen,
 524                 .maxlen         = sizeof(queue_maxlen),
 525                 .mode           = 0644,
 526                 .proc_handler   = proc_dointvec
 527         },
 528         { .ctl_name = 0 }
 529 };
 530 #endif
 531
 532 #ifdef CONFIG_PROC_FS
 533 static int ip_queue_show(struct seq_file *m, void *v)
 534 {
 535         read_lock_bh(&queue_lock);
 536
 537         seq_printf(m,
 538                       "Peer PID          : %d\n"
 539                       "Copy mode         : %hu\n"
 540                       "Copy range        : %u\n"
 541                       "Queue length      : %u\n"
 542                       "Queue max. length : %u\n"
 543                       "Queue dropped     : %u\n"
 544                       "Netlink dropped   : %u\n",
 545                       peer_pid,
 546                       copy_mode,
 547                       copy_range,
 548                       queue_total,
 549                       queue_maxlen,
 550                       queue_dropped,
 551                       queue_user_dropped);
 552
 553         read_unlock_bh(&queue_lock);
 554         return 0;
 555 }
 556
 557 static int ip_queue_open(struct inode *inode, struct file *file)
 558 {
 559         return single_open(file, ip_queue_show, NULL);
 560 }
 561
 562 static const struct file_operations ip_queue_proc_fops = {
 563         .open           = ip_queue_open,
 564         .read           = seq_read,
 565         .llseek         = seq_lseek,
 566         .release        = single_release,
 567         .owner          = THIS_MODULE,
 568 };
 569 #endif
 570
 571 static const struct nf_queue_handler nfqh = {
 572         .name   = "ip_queue",
 573         .outfn  = &ipq_enqueue_packet,
 574 };
 575
 576 static int __init ip_queue_init(void)
 577 {
 578         int status = -ENOMEM;
 579         struct proc_dir_entry *proc __maybe_unused;
 580
 581         netlink_register_notifier(&ipq_nl_notifier);
 582         ipqnl = netlink_kernel_create(&init_net, NETLINK_FIREWALL, 0,
 583                                       ipq_rcv_skb, NULL, THIS_MODULE);
 584         if (ipqnl == NULL) {
 585                 printk(KERN_ERR "ip_queue: failed to create netlink socket\n");
 586                 goto cleanup_netlink_notifier;
 587         }
 588
 589 #ifdef CONFIG_PROC_FS
 590         proc = proc_create(IPQ_PROC_FS_NAME, 0, init_net.proc_net,
 591                            &ip_queue_proc_fops);
 592         if (!proc) {
 593                 printk(KERN_ERR "ip_queue: failed to create proc entry\n");
 594                 goto cleanup_ipqnl;
 595         }
 596 #endif
 597         register_netdevice_notifier(&ipq_dev_notifier);
 598 #ifdef CONFIG_SYSCTL
 599         ipq_sysctl_header = register_sysctl_paths(net_ipv4_ctl_path, ipq_table);
 600 #endif
 601         status = nf_register_queue_handler(PF_INET, &nfqh);
 602         if (status < 0) {
 603                 printk(KERN_ERR "ip_queue: failed to register queue handler\n");
 604                 goto cleanup_sysctl;
 605         }
 606         return status;
 607
 608 cleanup_sysctl:
 609 #ifdef CONFIG_SYSCTL
 610         unregister_sysctl_table(ipq_sysctl_header);
 611 #endif
 612         unregister_netdevice_notifier(&ipq_dev_notifier);
 613         proc_net_remove(&init_net, IPQ_PROC_FS_NAME);
 614 cleanup_ipqnl: __maybe_unused
 615         netlink_kernel_release(ipqnl);
 616         mutex_lock(&ipqnl_mutex);
 617         mutex_unlock(&ipqnl_mutex);
 618
 619 cleanup_netlink_notifier:
 620         netlink_unregister_notifier(&ipq_nl_notifier);
 621         return status;
 622 }
 623
 624 static void __exit ip_queue_fini(void)
 625 {
 626         nf_unregister_queue_handlers(&nfqh);
 627         synchronize_net();
 628         ipq_flush(NULL, 0);
 629
 630 #ifdef CONFIG_SYSCTL
 631         unregister_sysctl_table(ipq_sysctl_header);
 632 #endif
 633         unregister_netdevice_notifier(&ipq_dev_notifier);
 634         proc_net_remove(&init_net, IPQ_PROC_FS_NAME);
 635
 636         netlink_kernel_release(ipqnl);
 637         mutex_lock(&ipqnl_mutex);
 638         mutex_unlock(&ipqnl_mutex);
 639
 640         netlink_unregister_notifier(&ipq_nl_notifier);
 641 }
 642
 643 MODULE_DESCRIPTION("IPv4 packet queue handler");
 644 MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");
 645 MODULE_LICENSE("GPL");
 646
 647 module_init(ip_queue_init);
 648 module_exit(ip_queue_fini);