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 <linux/slab.h>
  29 #include <net/net_namespace.h>
  30 #include <net/sock.h>
  31 #include <net/ipv6.h>
  32 #include <net/ip6_route.h>
  33 #include <net/netfilter/nf_queue.h>
  34 #include <linux/netfilter_ipv4/ip_queue.h>
  35 #include <linux/netfilter_ipv4/ip_tables.h>
  36 #include <linux/netfilter_ipv6/ip6_tables.h>
  37
  38 #define IPQ_QMAX_DEFAULT 1024
  39 #define IPQ_PROC_FS_NAME "ip6_queue"
  40 #define NET_IPQ_QMAX_NAME "ip6_queue_maxlen"
  41
  42 typedef int (*ipq_cmpfn)(struct nf_queue_entry *, unsigned long);
  43
  44 static unsigned char copy_mode __read_mostly = IPQ_COPY_NONE;
  45 static unsigned int queue_maxlen __read_mostly = IPQ_QMAX_DEFAULT;
  46 static DEFINE_SPINLOCK(queue_lock);
  47 static int peer_pid __read_mostly;
  48 static unsigned int copy_range __read_mostly;
  49 static unsigned int queue_total;
  50 static unsigned int queue_dropped = 0;
  51 static unsigned int queue_user_dropped = 0;
  52 static struct sock *ipqnl __read_mostly;
  53 static LIST_HEAD(queue_list);
  54 static DEFINE_MUTEX(ipqnl_mutex);
  55
  56 static inline void
  57 __ipq_enqueue_entry(struct nf_queue_entry *entry)
  58 {
  59        list_add_tail(&entry->list, &queue_list);
  60        queue_total++;
  61 }
  62
  63 static inline int
  64 __ipq_set_mode(unsigned char mode, unsigned int range)
  65 {
  66         int status = 0;
  67
  68         switch(mode) {
  69         case IPQ_COPY_NONE:
  70         case IPQ_COPY_META:
  71                 copy_mode = mode;
  72                 copy_range = 0;
  73                 break;
  74
  75         case IPQ_COPY_PACKET:
  76                 if (range > 0xFFFF)
  77                         range = 0xFFFF;
  78                 copy_range = range;
  79                 copy_mode = mode;
  80                 break;
  81
  82         default:
  83                 status = -EINVAL;
  84
  85         }
  86         return status;
  87 }
  88
  89 static void __ipq_flush(ipq_cmpfn cmpfn, unsigned long data);
  90
  91 static inline void
  92 __ipq_reset(void)
  93 {
  94         peer_pid = 0;
  95         net_disable_timestamp();
  96         __ipq_set_mode(IPQ_COPY_NONE, 0);
  97         __ipq_flush(NULL, 0);
  98 }
  99
 100 static struct nf_queue_entry *
 101 ipq_find_dequeue_entry(unsigned long id)
 102 {
 103         struct nf_queue_entry *entry = NULL, *i;
 104
 105         spin_lock_bh(&queue_lock);
 106
 107         list_for_each_entry(i, &queue_list, list) {
 108                 if ((unsigned long)i == id) {
 109                         entry = i;
 110                         break;
 111                 }
 112         }
 113
 114         if (entry) {
 115                 list_del(&entry->list);
 116                 queue_total--;
 117         }
 118
 119         spin_unlock_bh(&queue_lock);
 120         return entry;
 121 }
 122
 123 static void
 124 __ipq_flush(ipq_cmpfn cmpfn, unsigned long data)
 125 {
 126         struct nf_queue_entry *entry, *next;
 127
 128         list_for_each_entry_safe(entry, next, &queue_list, list) {
 129                 if (!cmpfn || cmpfn(entry, data)) {
 130                         list_del(&entry->list);
 131                         queue_total--;
 132                         nf_reinject(entry, NF_DROP);
 133                 }
 134         }
 135 }
 136
 137 static void
 138 ipq_flush(ipq_cmpfn cmpfn, unsigned long data)
 139 {
 140         spin_lock_bh(&queue_lock);
 141         __ipq_flush(cmpfn, data);
 142         spin_unlock_bh(&queue_lock);
 143 }
 144
 145 static struct sk_buff *
 146 ipq_build_packet_message(struct nf_queue_entry *entry, int *errp)
 147 {
 148         sk_buff_data_t old_tail;
 149         size_t size = 0;
 150         size_t data_len = 0;
 151         struct sk_buff *skb;
 152         struct ipq_packet_msg *pmsg;
 153         struct nlmsghdr *nlh;
 154         struct timeval tv;
 155
 156         switch (ACCESS_ONCE(copy_mode)) {
 157         case IPQ_COPY_META:
 158         case IPQ_COPY_NONE:
 159                 size = NLMSG_SPACE(sizeof(*pmsg));
 160                 break;
 161
 162         case IPQ_COPY_PACKET:
 163                 if (entry->skb->ip_summed == CHECKSUM_PARTIAL &&
 164                     (*errp = skb_checksum_help(entry->skb)))
 165                         return NULL;
 166
 167                 data_len = ACCESS_ONCE(copy_range);
 168                 if (data_len == 0 || data_len > entry->skb->len)
 169                         data_len = entry->skb->len;
 170
 171                 size = NLMSG_SPACE(sizeof(*pmsg) + data_len);
 172                 break;
 173
 174         default:
 175                 *errp = -EINVAL;
 176                 return NULL;
 177         }
 178
 179         skb = alloc_skb(size, GFP_ATOMIC);
 180         if (!skb)
 181                 goto nlmsg_failure;
 182
 183         old_tail = skb->tail;
 184         nlh = NLMSG_PUT(skb, 0, 0, IPQM_PACKET, size - sizeof(*nlh));
 185         pmsg = NLMSG_DATA(nlh);
 186         memset(pmsg, 0, sizeof(*pmsg));
 187
 188         pmsg->packet_id       = (unsigned long )entry;
 189         pmsg->data_len        = data_len;
 190         tv = ktime_to_timeval(entry->skb->tstamp);
 191         pmsg->timestamp_sec   = tv.tv_sec;
 192         pmsg->timestamp_usec  = tv.tv_usec;
 193         pmsg->mark            = entry->skb->mark;
 194         pmsg->hook            = entry->hook;
 195         pmsg->hw_protocol     = entry->skb->protocol;
 196
 197         if (entry->indev)
 198                 strcpy(pmsg->indev_name, entry->indev->name);
 199         else
 200                 pmsg->indev_name[0] = '\0';
 201
 202         if (entry->outdev)
 203                 strcpy(pmsg->outdev_name, entry->outdev->name);
 204         else
 205                 pmsg->outdev_name[0] = '\0';
 206
 207         if (entry->indev && entry->skb->dev &&
 208             entry->skb->mac_header != entry->skb->network_header) {
 209                 pmsg->hw_type = entry->skb->dev->type;
 210                 pmsg->hw_addrlen = dev_parse_header(entry->skb, pmsg->hw_addr);
 211         }
 212
 213         if (data_len)
 214                 if (skb_copy_bits(entry->skb, 0, pmsg->payload, data_len))
 215                         BUG();
 216
 217         nlh->nlmsg_len = skb->tail - old_tail;
 218         return skb;
 219
 220 nlmsg_failure:
 221         kfree_skb(skb);
 222         *errp = -EINVAL;
 223         printk(KERN_ERR "ip6_queue: error creating packet message\n");
 224         return NULL;
 225 }
 226
 227 static int
 228 ipq_enqueue_packet(struct nf_queue_entry *entry, unsigned int queuenum)
 229 {
 230         int status = -EINVAL;
 231         struct sk_buff *nskb;
 232
 233         if (copy_mode == IPQ_COPY_NONE)
 234                 return -EAGAIN;
 235
 236         nskb = ipq_build_packet_message(entry, &status);
 237         if (nskb == NULL)
 238                 return status;
 239
 240         spin_lock_bh(&queue_lock);
 241
 242         if (!peer_pid)
 243                 goto err_out_free_nskb;
 244
 245         if (queue_total >= queue_maxlen) {
 246                 queue_dropped++;
 247                 status = -ENOSPC;
 248                 if (net_ratelimit())
 249                         printk (KERN_WARNING "ip6_queue: fill at %d entries, "
 250                                 "dropping packet(s).  Dropped: %d\n", queue_total,
 251                                 queue_dropped);
 252                 goto err_out_free_nskb;
 253         }
 254
 255         /* netlink_unicast will either free the nskb or attach it to a socket */
 256         status = netlink_unicast(ipqnl, nskb, peer_pid, MSG_DONTWAIT);
 257         if (status < 0) {
 258                 queue_user_dropped++;
 259                 goto err_out_unlock;
 260         }
 261
 262         __ipq_enqueue_entry(entry);
 263
 264         spin_unlock_bh(&queue_lock);
 265         return status;
 266
 267 err_out_free_nskb:
 268         kfree_skb(nskb);
 269
 270 err_out_unlock:
 271         spin_unlock_bh(&queue_lock);
 272         return status;
 273 }
 274
 275 static int
 276 ipq_mangle_ipv6(ipq_verdict_msg_t *v, struct nf_queue_entry *e)
 277 {
 278         int diff;
 279         struct ipv6hdr *user_iph = (struct ipv6hdr *)v->payload;
 280         struct sk_buff *nskb;
 281
 282         if (v->data_len < sizeof(*user_iph))
 283                 return 0;
 284         diff = v->data_len - e->skb->len;
 285         if (diff < 0) {
 286                 if (pskb_trim(e->skb, v->data_len))
 287                         return -ENOMEM;
 288         } else if (diff > 0) {
 289                 if (v->data_len > 0xFFFF)
 290                         return -EINVAL;
 291                 if (diff > skb_tailroom(e->skb)) {
 292                         nskb = skb_copy_expand(e->skb, skb_headroom(e->skb),
 293                                                diff, GFP_ATOMIC);
 294                         if (!nskb) {
 295                                 printk(KERN_WARNING "ip6_queue: OOM "
 296                                       "in mangle, dropping packet\n");
 297                                 return -ENOMEM;
 298                         }
 299                         kfree_skb(e->skb);
 300                         e->skb = nskb;
 301                 }
 302                 skb_put(e->skb, diff);
 303         }
 304         if (!skb_make_writable(e->skb, v->data_len))
 305                 return -ENOMEM;
 306         skb_copy_to_linear_data(e->skb, v->payload, v->data_len);
 307         e->skb->ip_summed = CHECKSUM_NONE;
 308
 309         return 0;
 310 }
 311
 312 static int
 313 ipq_set_verdict(struct ipq_verdict_msg *vmsg, unsigned int len)
 314 {
 315         struct nf_queue_entry *entry;
 316
 317         if (vmsg->value > NF_MAX_VERDICT || vmsg->value == NF_STOLEN)
 318                 return -EINVAL;
 319
 320         entry = ipq_find_dequeue_entry(vmsg->id);
 321         if (entry == NULL)
 322                 return -ENOENT;
 323         else {
 324                 int verdict = vmsg->value;
 325
 326                 if (vmsg->data_len && vmsg->data_len == len)
 327                         if (ipq_mangle_ipv6(vmsg, entry) < 0)
 328                                 verdict = NF_DROP;
 329
 330                 nf_reinject(entry, verdict);
 331                 return 0;
 332         }
 333 }
 334
 335 static int
 336 ipq_set_mode(unsigned char mode, unsigned int range)
 337 {
 338         int status;
 339
 340         spin_lock_bh(&queue_lock);
 341         status = __ipq_set_mode(mode, range);
 342         spin_unlock_bh(&queue_lock);
 343         return status;
 344 }
 345
 346 static int
 347 ipq_receive_peer(struct ipq_peer_msg *pmsg,
 348                  unsigned char type, unsigned int len)
 349 {
 350         int status = 0;
 351
 352         if (len < sizeof(*pmsg))
 353                 return -EINVAL;
 354
 355         switch (type) {
 356         case IPQM_MODE:
 357                 status = ipq_set_mode(pmsg->msg.mode.value,
 358                                       pmsg->msg.mode.range);
 359                 break;
 360
 361         case IPQM_VERDICT:
 362                 status = ipq_set_verdict(&pmsg->msg.verdict,
 363                                          len - sizeof(*pmsg));
 364                 break;
 365         default:
 366                 status = -EINVAL;
 367         }
 368         return status;
 369 }
 370
 371 static int
 372 dev_cmp(struct nf_queue_entry *entry, unsigned long ifindex)
 373 {
 374         if (entry->indev)
 375                 if (entry->indev->ifindex == ifindex)
 376                         return 1;
 377
 378         if (entry->outdev)
 379                 if (entry->outdev->ifindex == ifindex)
 380                         return 1;
 381 #ifdef CONFIG_BRIDGE_NETFILTER
 382         if (entry->skb->nf_bridge) {
 383                 if (entry->skb->nf_bridge->physindev &&
 384                     entry->skb->nf_bridge->physindev->ifindex == ifindex)
 385                         return 1;
 386                 if (entry->skb->nf_bridge->physoutdev &&
 387                     entry->skb->nf_bridge->physoutdev->ifindex == ifindex)
 388                         return 1;
 389         }
 390 #endif
 391         return 0;
 392 }
 393
 394 static void
 395 ipq_dev_drop(int ifindex)
 396 {
 397         ipq_flush(dev_cmp, ifindex);
 398 }
 399
 400 #define RCV_SKB_FAIL(err) do { netlink_ack(skb, nlh, (err)); return; } while (0)
 401
 402 static inline void
 403 __ipq_rcv_skb(struct sk_buff *skb)
 404 {
 405         int status, type, pid, flags;
 406         unsigned int nlmsglen, skblen;
 407         struct nlmsghdr *nlh;
 408         bool enable_timestamp = false;
 409
 410         skblen = skb->len;
 411         if (skblen < sizeof(*nlh))
 412                 return;
 413
 414         nlh = nlmsg_hdr(skb);
 415         nlmsglen = nlh->nlmsg_len;
 416         if (nlmsglen < sizeof(*nlh) || skblen < nlmsglen)
 417                 return;
 418
 419         pid = nlh->nlmsg_pid;
 420         flags = nlh->nlmsg_flags;
 421
 422         if(pid <= 0 || !(flags & NLM_F_REQUEST) || flags & NLM_F_MULTI)
 423                 RCV_SKB_FAIL(-EINVAL);
 424
 425         if (flags & MSG_TRUNC)
 426                 RCV_SKB_FAIL(-ECOMM);
 427
 428         type = nlh->nlmsg_type;
 429         if (type < NLMSG_NOOP || type >= IPQM_MAX)
 430                 RCV_SKB_FAIL(-EINVAL);
 431
 432         if (type <= IPQM_BASE)
 433                 return;
 434
 435         if (!capable(CAP_NET_ADMIN))
 436                 RCV_SKB_FAIL(-EPERM);
 437
 438         spin_lock_bh(&queue_lock);
 439
 440         if (peer_pid) {
 441                 if (peer_pid != pid) {
 442                         spin_unlock_bh(&queue_lock);
 443                         RCV_SKB_FAIL(-EBUSY);
 444                 }
 445         } else {
 446                 enable_timestamp = true;
 447                 peer_pid = pid;
 448         }
 449
 450         spin_unlock_bh(&queue_lock);
 451         if (enable_timestamp)
 452                 net_enable_timestamp();
 453
 454         status = ipq_receive_peer(NLMSG_DATA(nlh), type,
 455                                   nlmsglen - NLMSG_LENGTH(0));
 456         if (status < 0)
 457                 RCV_SKB_FAIL(status);
 458
 459         if (flags & NLM_F_ACK)
 460                 netlink_ack(skb, nlh, 0);
 461 }
 462
 463 static void
 464 ipq_rcv_skb(struct sk_buff *skb)
 465 {
 466         mutex_lock(&ipqnl_mutex);
 467         __ipq_rcv_skb(skb);
 468         mutex_unlock(&ipqnl_mutex);
 469 }
 470
 471 static int
 472 ipq_rcv_dev_event(struct notifier_block *this,
 473                   unsigned long event, void *ptr)
 474 {
 475         struct net_device *dev = ptr;
 476
 477         if (!net_eq(dev_net(dev), &init_net))
 478                 return NOTIFY_DONE;
 479
 480         /* Drop any packets associated with the downed device */
 481         if (event == NETDEV_DOWN)
 482                 ipq_dev_drop(dev->ifindex);
 483         return NOTIFY_DONE;
 484 }
 485
 486 static struct notifier_block ipq_dev_notifier = {
 487         .notifier_call  = ipq_rcv_dev_event,
 488 };
 489
 490 static int
 491 ipq_rcv_nl_event(struct notifier_block *this,
 492                  unsigned long event, void *ptr)
 493 {
 494         struct netlink_notify *n = ptr;
 495
 496         if (event == NETLINK_URELEASE && n->protocol == NETLINK_IP6_FW) {
 497                 spin_lock_bh(&queue_lock);
 498                 if ((net_eq(n->net, &init_net)) && (n->pid == peer_pid))
 499                         __ipq_reset();
 500                 spin_unlock_bh(&queue_lock);
 501         }
 502         return NOTIFY_DONE;
 503 }
 504
 505 static struct notifier_block ipq_nl_notifier = {
 506         .notifier_call  = ipq_rcv_nl_event,
 507 };
 508
 509 #ifdef CONFIG_SYSCTL
 510 static struct ctl_table_header *ipq_sysctl_header;
 511
 512 static ctl_table ipq_table[] = {
 513         {
 514                 .procname       = NET_IPQ_QMAX_NAME,
 515                 .data           = &queue_maxlen,
 516                 .maxlen         = sizeof(queue_maxlen),
 517                 .mode           = 0644,
 518                 .proc_handler   = proc_dointvec
 519         },
 520         { }
 521 };
 522 #endif
 523
 524 #ifdef CONFIG_PROC_FS
 525 static int ip6_queue_show(struct seq_file *m, void *v)
 526 {
 527         spin_lock_bh(&queue_lock);
 528
 529         seq_printf(m,
 530                       "Peer PID          : %d\n"
 531                       "Copy mode         : %hu\n"
 532                       "Copy range        : %u\n"
 533                       "Queue length      : %u\n"
 534                       "Queue max. length : %u\n"
 535                       "Queue dropped     : %u\n"
 536                       "Netfilter dropped : %u\n",
 537                       peer_pid,
 538                       copy_mode,
 539                       copy_range,
 540                       queue_total,
 541                       queue_maxlen,
 542                       queue_dropped,
 543                       queue_user_dropped);
 544
 545         spin_unlock_bh(&queue_lock);
 546         return 0;
 547 }
 548
 549 static int ip6_queue_open(struct inode *inode, struct file *file)
 550 {
 551         return single_open(file, ip6_queue_show, NULL);
 552 }
 553
 554 static const struct file_operations ip6_queue_proc_fops = {
 555         .open           = ip6_queue_open,
 556         .read           = seq_read,
 557         .llseek         = seq_lseek,
 558         .release        = single_release,
 559         .owner          = THIS_MODULE,
 560 };
 561 #endif
 562
 563 static const struct nf_queue_handler nfqh = {
 564         .name   = "ip6_queue",
 565         .outfn  = &ipq_enqueue_packet,
 566 };
 567
 568 static int __init ip6_queue_init(void)
 569 {
 570         int status = -ENOMEM;
 571         struct proc_dir_entry *proc __maybe_unused;
 572
 573         netlink_register_notifier(&ipq_nl_notifier);
 574         ipqnl = netlink_kernel_create(&init_net, NETLINK_IP6_FW, 0,
 575                                       ipq_rcv_skb, NULL, THIS_MODULE);
 576         if (ipqnl == NULL) {
 577                 printk(KERN_ERR "ip6_queue: failed to create netlink socket\n");
 578                 goto cleanup_netlink_notifier;
 579         }
 580
 581 #ifdef CONFIG_PROC_FS
 582         proc = proc_create(IPQ_PROC_FS_NAME, 0, init_net.proc_net,
 583                            &ip6_queue_proc_fops);
 584         if (!proc) {
 585                 printk(KERN_ERR "ip6_queue: failed to create proc entry\n");
 586                 goto cleanup_ipqnl;
 587         }
 588 #endif
 589         register_netdevice_notifier(&ipq_dev_notifier);
 590 #ifdef CONFIG_SYSCTL
 591         ipq_sysctl_header = register_net_sysctl(&init_net, "net/ipv6", ipq_table);
 592 #endif
 593         status = nf_register_queue_handler(NFPROTO_IPV6, &nfqh);
 594         if (status < 0) {
 595                 printk(KERN_ERR "ip6_queue: failed to register queue handler\n");
 596                 goto cleanup_sysctl;
 597         }
 598         return status;
 599
 600 cleanup_sysctl:
 601 #ifdef CONFIG_SYSCTL
 602         unregister_net_sysctl_table(ipq_sysctl_header);
 603 #endif
 604         unregister_netdevice_notifier(&ipq_dev_notifier);
 605         proc_net_remove(&init_net, IPQ_PROC_FS_NAME);
 606
 607 cleanup_ipqnl: __maybe_unused
 608         netlink_kernel_release(ipqnl);
 609         mutex_lock(&ipqnl_mutex);
 610         mutex_unlock(&ipqnl_mutex);
 611
 612 cleanup_netlink_notifier:
 613         netlink_unregister_notifier(&ipq_nl_notifier);
 614         return status;
 615 }
 616
 617 static void __exit ip6_queue_fini(void)
 618 {
 619         nf_unregister_queue_handlers(&nfqh);
 620
 621         ipq_flush(NULL, 0);
 622
 623 #ifdef CONFIG_SYSCTL
 624         unregister_net_sysctl_table(ipq_sysctl_header);
 625 #endif
 626         unregister_netdevice_notifier(&ipq_dev_notifier);
 627         proc_net_remove(&init_net, IPQ_PROC_FS_NAME);
 628
 629         netlink_kernel_release(ipqnl);
 630         mutex_lock(&ipqnl_mutex);
 631         mutex_unlock(&ipqnl_mutex);
 632
 633         netlink_unregister_notifier(&ipq_nl_notifier);
 634 }
 635
 636 MODULE_DESCRIPTION("IPv6 packet queue handler");
 637 MODULE_LICENSE("GPL");
 638 MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_IP6_FW);
 639
 640 module_init(ip6_queue_init);
 641 module_exit(ip6_queue_fini);