net/ipv6/netfilter/ip6_queue.c

   1 /*
   2  * This is a module which is used for queueing IPv6 packets and
   3  * communicating with userspace via netlink.
   4  *
   5  * (C) 2001 Fernando Anton, this code is GPL.
   6  *     IPv64 Project - Work based in IPv64 draft by Arturo Azcorra.
   7  *     Universidad Carlos III de Madrid - Leganes (Madrid) - Spain
   8  *     Universidad Politecnica de Alcala de Henares - Alcala de H. (Madrid) - Spain
   9  *     email: fanton@it.uc3m.es
  10  *
  11  * This program is free software; you can redistribute it and/or modify
  12  * it under the terms of the GNU General Public License version 2 as
  13  * published by the Free Software Foundation.
  14  */
  15 #include <linux/module.h>
  16 #include <linux/skbuff.h>
  17 #include <linux/init.h>
  18 #include <linux/ipv6.h>
  19 #include <linux/notifier.h>
  20 #include <linux/netdevice.h>
  21 #include <linux/netfilter.h>
  22 #include <linux/netlink.h>
  23 #include <linux/spinlock.h>
  24 #include <linux/sysctl.h>
  25 #include <linux/proc_fs.h>
  26 #include <linux/seq_file.h>
  27 #include <linux/mutex.h>
  28 #include <net/net_namespace.h>
  29 #include <net/sock.h>
  30 #include <net/ipv6.h>
  31 #include <net/ip6_route.h>
  32 #include <net/netfilter/nf_queue.h>
  33 #include <linux/netfilter_ipv4/ip_queue.h>
  34 #include <linux/netfilter_ipv4/ip_tables.h>
  35 #include <linux/netfilter_ipv6/ip6_tables.h>
  36
  37 #define IPQ_QMAX_DEFAULT 1024
  38 #define IPQ_PROC_FS_NAME "ip6_queue"
  39 #define NET_IPQ_QMAX 2088
  40 #define NET_IPQ_QMAX_NAME "ip6_queue_maxlen"
  41
  42 struct ipq_queue_entry {
  43         struct list_head list;
  44         struct nf_info *info;
  45         struct sk_buff *skb;
  46 };
  47
  48 typedef int (*ipq_cmpfn)(struct ipq_queue_entry *, unsigned long);
  49
  50 static unsigned char copy_mode __read_mostly = IPQ_COPY_NONE;
  51 static unsigned int queue_maxlen __read_mostly = IPQ_QMAX_DEFAULT;
  52 static DEFINE_RWLOCK(queue_lock);
  53 static int peer_pid __read_mostly;
  54 static unsigned int copy_range __read_mostly;
  55 static unsigned int queue_total;
  56 static unsigned int queue_dropped = 0;
  57 static unsigned int queue_user_dropped = 0;
  58 static struct sock *ipqnl __read_mostly;
  59 static LIST_HEAD(queue_list);
  60 static DEFINE_MUTEX(ipqnl_mutex);
  61
  62 static void
  63 ipq_issue_verdict(struct ipq_queue_entry *entry, int verdict)
  64 {
  65         local_bh_disable();
  66         nf_reinject(entry->skb, entry->info, verdict);
  67         local_bh_enable();
  68         kfree(entry);
  69 }
  70
  71 static inline void
  72 __ipq_enqueue_entry(struct ipq_queue_entry *entry)
  73 {
  74        list_add_tail(&entry->list, &queue_list);
  75        queue_total++;
  76 }
  77
  78 static inline int
  79 __ipq_set_mode(unsigned char mode, unsigned int range)
  80 {
  81         int status = 0;
  82
  83         switch(mode) {
  84         case IPQ_COPY_NONE:
  85         case IPQ_COPY_META:
  86                 copy_mode = mode;
  87                 copy_range = 0;
  88                 break;
  89
  90         case IPQ_COPY_PACKET:
  91                 copy_mode = mode;
  92                 copy_range = range;
  93                 if (copy_range > 0xFFFF)
  94                         copy_range = 0xFFFF;
  95                 break;
  96
  97         default:
  98                 status = -EINVAL;
  99
 100         }
 101         return status;
 102 }
 103
 104 static void __ipq_flush(ipq_cmpfn cmpfn, unsigned long data);
 105
 106 static inline void
 107 __ipq_reset(void)
 108 {
 109         peer_pid = 0;
 110         net_disable_timestamp();
 111         __ipq_set_mode(IPQ_COPY_NONE, 0);
 112         __ipq_flush(NULL, 0);
 113 }
 114
 115 static struct ipq_queue_entry *
 116 ipq_find_dequeue_entry(unsigned long id)
 117 {
 118         struct ipq_queue_entry *entry = NULL, *i;
 119
 120         write_lock_bh(&queue_lock);
 121
 122         list_for_each_entry(i, &queue_list, list) {
 123                 if ((unsigned long)i == id) {
 124                         entry = i;
 125                         break;
 126                 }
 127         }
 128
 129         if (entry) {
 130                 list_del(&entry->list);
 131                 queue_total--;
 132         }
 133
 134         write_unlock_bh(&queue_lock);
 135         return entry;
 136 }
 137
 138 static void
 139 __ipq_flush(ipq_cmpfn cmpfn, unsigned long data)
 140 {
 141         struct ipq_queue_entry *entry, *next;
 142
 143         list_for_each_entry_safe(entry, next, &queue_list, list) {
 144                 if (!cmpfn || cmpfn(entry, data)) {
 145                         list_del(&entry->list);
 146                         queue_total--;
 147                         ipq_issue_verdict(entry, NF_DROP);
 148                 }
 149         }
 150 }
 151
 152 static void
 153 ipq_flush(ipq_cmpfn cmpfn, unsigned long data)
 154 {
 155         write_lock_bh(&queue_lock);
 156         __ipq_flush(cmpfn, data);
 157         write_unlock_bh(&queue_lock);
 158 }
 159
 160 static struct sk_buff *
 161 ipq_build_packet_message(struct ipq_queue_entry *entry, int *errp)
 162 {
 163         sk_buff_data_t old_tail;
 164         size_t size = 0;
 165         size_t data_len = 0;
 166         struct sk_buff *skb;
 167         struct ipq_packet_msg *pmsg;
 168         struct nlmsghdr *nlh;
 169         struct timeval tv;
 170
 171         read_lock_bh(&queue_lock);
 172
 173         switch (copy_mode) {
 174         case IPQ_COPY_META:
 175         case IPQ_COPY_NONE:
 176                 size = NLMSG_SPACE(sizeof(*pmsg));
 177                 data_len = 0;
 178                 break;
 179
 180         case IPQ_COPY_PACKET:
 181                 if ((entry->skb->ip_summed == CHECKSUM_PARTIAL ||
 182                      entry->skb->ip_summed == CHECKSUM_COMPLETE) &&
 183                     (*errp = skb_checksum_help(entry->skb))) {
 184                         read_unlock_bh(&queue_lock);
 185                         return NULL;
 186                 }
 187                 if (copy_range == 0 || copy_range > entry->skb->len)
 188                         data_len = entry->skb->len;
 189                 else
 190                         data_len = copy_range;
 191
 192                 size = NLMSG_SPACE(sizeof(*pmsg) + data_len);
 193                 break;
 194
 195         default:
 196                 *errp = -EINVAL;
 197                 read_unlock_bh(&queue_lock);
 198                 return NULL;
 199         }
 200
 201         read_unlock_bh(&queue_lock);
 202
 203         skb = alloc_skb(size, GFP_ATOMIC);
 204         if (!skb)
 205                 goto nlmsg_failure;
 206
 207         old_tail = skb->tail;
 208         nlh = NLMSG_PUT(skb, 0, 0, IPQM_PACKET, size - sizeof(*nlh));
 209         pmsg = NLMSG_DATA(nlh);
 210         memset(pmsg, 0, sizeof(*pmsg));
 211
 212         pmsg->packet_id       = (unsigned long )entry;
 213         pmsg->data_len        = data_len;
 214         tv = ktime_to_timeval(entry->skb->tstamp);
 215         pmsg->timestamp_sec   = tv.tv_sec;
 216         pmsg->timestamp_usec  = tv.tv_usec;
 217         pmsg->mark            = entry->skb->mark;
 218         pmsg->hook            = entry->info->hook;
 219         pmsg->hw_protocol     = entry->skb->protocol;
 220
 221         if (entry->info->indev)
 222                 strcpy(pmsg->indev_name, entry->info->indev->name);
 223         else
 224                 pmsg->indev_name[0] = '\0';
 225
 226         if (entry->info->outdev)
 227                 strcpy(pmsg->outdev_name, entry->info->outdev->name);
 228         else
 229                 pmsg->outdev_name[0] = '\0';
 230
 231         if (entry->info->indev && entry->skb->dev) {
 232                 pmsg->hw_type = entry->skb->dev->type;
 233                 pmsg->hw_addrlen = dev_parse_header(entry->skb, pmsg->hw_addr);
 234         }
 235
 236         if (data_len)
 237                 if (skb_copy_bits(entry->skb, 0, pmsg->payload, data_len))
 238                         BUG();
 239
 240         nlh->nlmsg_len = skb->tail - old_tail;
 241         return skb;
 242
 243 nlmsg_failure:
 244         if (skb)
 245                 kfree_skb(skb);
 246         *errp = -EINVAL;
 247         printk(KERN_ERR "ip6_queue: error creating packet message\n");
 248         return NULL;
 249 }
 250
 251 static int
 252 ipq_enqueue_packet(struct sk_buff *skb, struct nf_info *info,
 253                    unsigned int queuenum)
 254 {
 255         int status = -EINVAL;
 256         struct sk_buff *nskb;
 257         struct ipq_queue_entry *entry;
 258
 259         if (copy_mode == IPQ_COPY_NONE)
 260                 return -EAGAIN;
 261
 262         entry = kmalloc(sizeof(*entry), GFP_ATOMIC);
 263         if (entry == NULL) {
 264                 printk(KERN_ERR "ip6_queue: OOM in ipq_enqueue_packet()\n");
 265                 return -ENOMEM;
 266         }
 267
 268         entry->info = info;
 269         entry->skb = skb;
 270
 271         nskb = ipq_build_packet_message(entry, &status);
 272         if (nskb == NULL)
 273                 goto err_out_free;
 274
 275         write_lock_bh(&queue_lock);
 276
 277         if (!peer_pid)
 278                 goto err_out_free_nskb;
 279
 280         if (queue_total >= queue_maxlen) {
 281                 queue_dropped++;
 282                 status = -ENOSPC;
 283                 if (net_ratelimit())
 284                         printk (KERN_WARNING "ip6_queue: fill at %d entries, "
 285                                 "dropping packet(s).  Dropped: %d\n", queue_total,
 286                                 queue_dropped);
 287                 goto err_out_free_nskb;
 288         }
 289
 290         /* netlink_unicast will either free the nskb or attach it to a socket */
 291         status = netlink_unicast(ipqnl, nskb, peer_pid, MSG_DONTWAIT);
 292         if (status < 0) {
 293                 queue_user_dropped++;
 294                 goto err_out_unlock;
 295         }
 296
 297         __ipq_enqueue_entry(entry);
 298
 299         write_unlock_bh(&queue_lock);
 300         return status;
 301
 302 err_out_free_nskb:
 303         kfree_skb(nskb);
 304
 305 err_out_unlock:
 306         write_unlock_bh(&queue_lock);
 307
 308 err_out_free:
 309         kfree(entry);
 310         return status;
 311 }
 312
 313 static int
 314 ipq_mangle_ipv6(ipq_verdict_msg_t *v, struct ipq_queue_entry *e)
 315 {
 316         int diff;
 317         int err;
 318         struct ipv6hdr *user_iph = (struct ipv6hdr *)v->payload;
 319
 320         if (v->data_len < sizeof(*user_iph))
 321                 return 0;
 322         diff = v->data_len - e->skb->len;
 323         if (diff < 0) {
 324                 if (pskb_trim(e->skb, v->data_len))
 325                         return -ENOMEM;
 326         } else if (diff > 0) {
 327                 if (v->data_len > 0xFFFF)
 328                         return -EINVAL;
 329                 if (diff > skb_tailroom(e->skb)) {
 330                         err = pskb_expand_head(e->skb, 0,
 331                                                diff - skb_tailroom(e->skb),
 332                                                GFP_ATOMIC);
 333                         if (err) {
 334                                 printk(KERN_WARNING "ip6_queue: OOM "
 335                                       "in mangle, dropping packet\n");
 336                                 return err;
 337                         }
 338                 }
 339                 skb_put(e->skb, diff);
 340         }
 341         if (!skb_make_writable(e->skb, v->data_len))
 342                 return -ENOMEM;
 343         skb_copy_to_linear_data(e->skb, v->payload, v->data_len);
 344         e->skb->ip_summed = CHECKSUM_NONE;
 345
 346         return 0;
 347 }
 348
 349 static int
 350 ipq_set_verdict(struct ipq_verdict_msg *vmsg, unsigned int len)
 351 {
 352         struct ipq_queue_entry *entry;
 353
 354         if (vmsg->value > NF_MAX_VERDICT)
 355                 return -EINVAL;
 356
 357         entry = ipq_find_dequeue_entry(vmsg->id);
 358         if (entry == NULL)
 359                 return -ENOENT;
 360         else {
 361                 int verdict = vmsg->value;
 362
 363                 if (vmsg->data_len && vmsg->data_len == len)
 364                         if (ipq_mangle_ipv6(vmsg, entry) < 0)
 365                                 verdict = NF_DROP;
 366
 367                 ipq_issue_verdict(entry, verdict);
 368                 return 0;
 369         }
 370 }
 371
 372 static int
 373 ipq_set_mode(unsigned char mode, unsigned int range)
 374 {
 375         int status;
 376
 377         write_lock_bh(&queue_lock);
 378         status = __ipq_set_mode(mode, range);
 379         write_unlock_bh(&queue_lock);
 380         return status;
 381 }
 382
 383 static int
 384 ipq_receive_peer(struct ipq_peer_msg *pmsg,
 385                  unsigned char type, unsigned int len)
 386 {
 387         int status = 0;
 388
 389         if (len < sizeof(*pmsg))
 390                 return -EINVAL;
 391
 392         switch (type) {
 393         case IPQM_MODE:
 394                 status = ipq_set_mode(pmsg->msg.mode.value,
 395                                       pmsg->msg.mode.range);
 396                 break;
 397
 398         case IPQM_VERDICT:
 399                 if (pmsg->msg.verdict.value > NF_MAX_VERDICT)
 400                         status = -EINVAL;
 401                 else
 402                         status = ipq_set_verdict(&pmsg->msg.verdict,
 403                                                  len - sizeof(*pmsg));
 404                         break;
 405         default:
 406                 status = -EINVAL;
 407         }
 408         return status;
 409 }
 410
 411 static int
 412 dev_cmp(struct ipq_queue_entry *entry, unsigned long ifindex)
 413 {
 414         if (entry->info->indev)
 415                 if (entry->info->indev->ifindex == ifindex)
 416                         return 1;
 417
 418         if (entry->info->outdev)
 419                 if (entry->info->outdev->ifindex == ifindex)
 420                         return 1;
 421
 422         return 0;
 423 }
 424
 425 static void
 426 ipq_dev_drop(int ifindex)
 427 {
 428         ipq_flush(dev_cmp, ifindex);
 429 }
 430
 431 #define RCV_SKB_FAIL(err) do { netlink_ack(skb, nlh, (err)); return; } while (0)
 432
 433 static inline void
 434 __ipq_rcv_skb(struct sk_buff *skb)
 435 {
 436         int status, type, pid, flags, nlmsglen, skblen;
 437         struct nlmsghdr *nlh;
 438
 439         skblen = skb->len;
 440         if (skblen < sizeof(*nlh))
 441                 return;
 442
 443         nlh = nlmsg_hdr(skb);
 444         nlmsglen = nlh->nlmsg_len;
 445         if (nlmsglen < sizeof(*nlh) || skblen < nlmsglen)
 446                 return;
 447
 448         pid = nlh->nlmsg_pid;
 449         flags = nlh->nlmsg_flags;
 450
 451         if(pid <= 0 || !(flags & NLM_F_REQUEST) || flags & NLM_F_MULTI)
 452                 RCV_SKB_FAIL(-EINVAL);
 453
 454         if (flags & MSG_TRUNC)
 455                 RCV_SKB_FAIL(-ECOMM);
 456
 457         type = nlh->nlmsg_type;
 458         if (type < NLMSG_NOOP || type >= IPQM_MAX)
 459                 RCV_SKB_FAIL(-EINVAL);
 460
 461         if (type <= IPQM_BASE)
 462                 return;
 463
 464         if (security_netlink_recv(skb, CAP_NET_ADMIN))
 465                 RCV_SKB_FAIL(-EPERM);
 466
 467         write_lock_bh(&queue_lock);
 468
 469         if (peer_pid) {
 470                 if (peer_pid != pid) {
 471                         write_unlock_bh(&queue_lock);
 472                         RCV_SKB_FAIL(-EBUSY);
 473                 }
 474         } else {
 475                 net_enable_timestamp();
 476                 peer_pid = pid;
 477         }
 478
 479         write_unlock_bh(&queue_lock);
 480
 481         status = ipq_receive_peer(NLMSG_DATA(nlh), type,
 482                                   nlmsglen - NLMSG_LENGTH(0));
 483         if (status < 0)
 484                 RCV_SKB_FAIL(status);
 485
 486         if (flags & NLM_F_ACK)
 487                 netlink_ack(skb, nlh, 0);
 488         return;
 489 }
 490
 491 static void
 492 ipq_rcv_skb(struct sk_buff *skb)
 493 {
 494         mutex_lock(&ipqnl_mutex);
 495         __ipq_rcv_skb(skb);
 496         mutex_unlock(&ipqnl_mutex);
 497 }
 498
 499 static int
 500 ipq_rcv_dev_event(struct notifier_block *this,
 501                   unsigned long event, void *ptr)
 502 {
 503         struct net_device *dev = ptr;
 504
 505         if (dev->nd_net != &init_net)
 506                 return NOTIFY_DONE;
 507
 508         /* Drop any packets associated with the downed device */
 509         if (event == NETDEV_DOWN)
 510                 ipq_dev_drop(dev->ifindex);
 511         return NOTIFY_DONE;
 512 }
 513
 514 static struct notifier_block ipq_dev_notifier = {
 515         .notifier_call  = ipq_rcv_dev_event,
 516 };
 517
 518 static int
 519 ipq_rcv_nl_event(struct notifier_block *this,
 520                  unsigned long event, void *ptr)
 521 {
 522         struct netlink_notify *n = ptr;
 523
 524         if (event == NETLINK_URELEASE &&
 525             n->protocol == NETLINK_IP6_FW && n->pid) {
 526                 write_lock_bh(&queue_lock);
 527                 if ((n->net == &init_net) && (n->pid == peer_pid))
 528                         __ipq_reset();
 529                 write_unlock_bh(&queue_lock);
 530         }
 531         return NOTIFY_DONE;
 532 }
 533
 534 static struct notifier_block ipq_nl_notifier = {
 535         .notifier_call  = ipq_rcv_nl_event,
 536 };
 537
 538 static struct ctl_table_header *ipq_sysctl_header;
 539
 540 static ctl_table ipq_table[] = {
 541         {
 542                 .ctl_name       = NET_IPQ_QMAX,
 543                 .procname       = NET_IPQ_QMAX_NAME,
 544                 .data           = &queue_maxlen,
 545                 .maxlen         = sizeof(queue_maxlen),
 546                 .mode           = 0644,
 547                 .proc_handler   = proc_dointvec
 548         },
 549         { .ctl_name = 0 }
 550 };
 551
 552 static ctl_table ipq_dir_table[] = {
 553         {
 554                 .ctl_name       = NET_IPV6,
 555                 .procname       = "ipv6",
 556                 .mode           = 0555,
 557                 .child          = ipq_table
 558         },
 559         { .ctl_name = 0 }
 560 };
 561
 562 static ctl_table ipq_root_table[] = {
 563         {
 564                 .ctl_name       = CTL_NET,
 565                 .procname       = "net",
 566                 .mode           = 0555,
 567                 .child          = ipq_dir_table
 568         },
 569         { .ctl_name = 0 }
 570 };
 571
 572 static int ip6_queue_show(struct seq_file *m, void *v)
 573 {
 574         read_lock_bh(&queue_lock);
 575
 576         seq_printf(m,
 577                       "Peer PID          : %d\n"
 578                       "Copy mode         : %hu\n"
 579                       "Copy range        : %u\n"
 580                       "Queue length      : %u\n"
 581                       "Queue max. length : %u\n"
 582                       "Queue dropped     : %u\n"
 583                       "Netfilter dropped : %u\n",
 584                       peer_pid,
 585                       copy_mode,
 586                       copy_range,
 587                       queue_total,
 588                       queue_maxlen,
 589                       queue_dropped,
 590                       queue_user_dropped);
 591
 592         read_unlock_bh(&queue_lock);
 593         return 0;
 594 }
 595
 596 static int ip6_queue_open(struct inode *inode, struct file *file)
 597 {
 598         return single_open(file, ip6_queue_show, NULL);
 599 }
 600
 601 static const struct file_operations ip6_queue_proc_fops = {
 602         .open           = ip6_queue_open,
 603         .read           = seq_read,
 604         .llseek         = seq_lseek,
 605         .release        = single_release,
 606         .owner          = THIS_MODULE,
 607 };
 608
 609 static const struct nf_queue_handler nfqh = {
 610         .name   = "ip6_queue",
 611         .outfn  = &ipq_enqueue_packet,
 612 };
 613
 614 static int __init ip6_queue_init(void)
 615 {
 616         int status = -ENOMEM;
 617         struct proc_dir_entry *proc;
 618
 619         netlink_register_notifier(&ipq_nl_notifier);
 620         ipqnl = netlink_kernel_create(&init_net, NETLINK_IP6_FW, 0,
 621                                       ipq_rcv_skb, NULL, THIS_MODULE);
 622         if (ipqnl == NULL) {
 623                 printk(KERN_ERR "ip6_queue: failed to create netlink socket\n");
 624                 goto cleanup_netlink_notifier;
 625         }
 626
 627         proc = create_proc_entry(IPQ_PROC_FS_NAME, 0, init_net.proc_net);
 628         if (proc) {
 629                 proc->owner = THIS_MODULE;
 630                 proc->proc_fops = &ip6_queue_proc_fops;
 631         } else {
 632                 printk(KERN_ERR "ip6_queue: failed to create proc entry\n");
 633                 goto cleanup_ipqnl;
 634         }
 635
 636         register_netdevice_notifier(&ipq_dev_notifier);
 637         ipq_sysctl_header = register_sysctl_table(ipq_root_table);
 638
 639         status = nf_register_queue_handler(PF_INET6, &nfqh);
 640         if (status < 0) {
 641                 printk(KERN_ERR "ip6_queue: failed to register queue handler\n");
 642                 goto cleanup_sysctl;
 643         }
 644         return status;
 645
 646 cleanup_sysctl:
 647         unregister_sysctl_table(ipq_sysctl_header);
 648         unregister_netdevice_notifier(&ipq_dev_notifier);
 649         proc_net_remove(&init_net, IPQ_PROC_FS_NAME);
 650
 651 cleanup_ipqnl:
 652         sock_release(ipqnl->sk_socket);
 653         mutex_lock(&ipqnl_mutex);
 654         mutex_unlock(&ipqnl_mutex);
 655
 656 cleanup_netlink_notifier:
 657         netlink_unregister_notifier(&ipq_nl_notifier);
 658         return status;
 659 }
 660
 661 static void __exit ip6_queue_fini(void)
 662 {
 663         nf_unregister_queue_handlers(&nfqh);
 664         synchronize_net();
 665         ipq_flush(NULL, 0);
 666
 667         unregister_sysctl_table(ipq_sysctl_header);
 668         unregister_netdevice_notifier(&ipq_dev_notifier);
 669         proc_net_remove(&init_net, IPQ_PROC_FS_NAME);
 670
 671         sock_release(ipqnl->sk_socket);
 672         mutex_lock(&ipqnl_mutex);
 673         mutex_unlock(&ipqnl_mutex);
 674
 675         netlink_unregister_notifier(&ipq_nl_notifier);
 676 }
 677
 678 MODULE_DESCRIPTION("IPv6 packet queue handler");
 679 MODULE_LICENSE("GPL");
 680
 681 module_init(ip6_queue_init);
 682 module_exit(ip6_queue_fini);