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/net.h>
  28 #include <linux/mutex.h>
  29 #include <linux/slab.h>
  30 #include <net/net_namespace.h>
  31 #include <net/sock.h>
  32 #include <net/route.h>
  33 #include <net/netfilter/nf_queue.h>
  34 #include <net/ip.h>
  35
  36 #define IPQ_QMAX_DEFAULT 1024
  37 #define IPQ_PROC_FS_NAME "ip_queue"
  38 #define NET_IPQ_QMAX 2088
  39 #define NET_IPQ_QMAX_NAME "ip_queue_maxlen"
  40
  41 typedef int (*ipq_cmpfn)(struct nf_queue_entry *, unsigned long);
  42
  43 static unsigned char copy_mode __read_mostly = IPQ_COPY_NONE;
  44 static unsigned int queue_maxlen __read_mostly = IPQ_QMAX_DEFAULT;
  45 static DEFINE_SPINLOCK(queue_lock);
  46 static int peer_pid __read_mostly;
  47 static unsigned int copy_range __read_mostly;
  48 static unsigned int queue_total;
  49 static unsigned int queue_dropped = 0;
  50 static unsigned int queue_user_dropped = 0;
  51 static struct sock *ipqnl __read_mostly;
  52 static LIST_HEAD(queue_list);
  53 static DEFINE_MUTEX(ipqnl_mutex);
  54
  55 static inline void
  56 __ipq_enqueue_entry(struct nf_queue_entry *entry)
  57 {
  58        list_add_tail(&entry->list, &queue_list);
  59        queue_total++;
  60 }
  61
  62 static inline int
  63 __ipq_set_mode(unsigned char mode, unsigned int range)
  64 {
  65         int status = 0;
  66
  67         switch(mode) {
  68         case IPQ_COPY_NONE:
  69         case IPQ_COPY_META:
  70                 copy_mode = mode;
  71                 copy_range = 0;
  72                 break;
  73
  74         case IPQ_COPY_PACKET:
  75                 if (range > 0xFFFF)
  76                         range = 0xFFFF;
  77                 copy_range = range;
  78                 copy_mode = mode;
  79                 break;
  80
  81         default:
  82                 status = -EINVAL;
  83
  84         }
  85         return status;
  86 }
  87
  88 static void __ipq_flush(ipq_cmpfn cmpfn, unsigned long data);
  89
  90 static inline void
  91 __ipq_reset(void)
  92 {
  93         peer_pid = 0;
  94         net_disable_timestamp();
  95         __ipq_set_mode(IPQ_COPY_NONE, 0);
  96         __ipq_flush(NULL, 0);
  97 }
  98
  99 static struct nf_queue_entry *
 100 ipq_find_dequeue_entry(unsigned long id)
 101 {
 102         struct nf_queue_entry *entry = NULL, *i;
 103
 104         spin_lock_bh(&queue_lock);
 105
 106         list_for_each_entry(i, &queue_list, list) {
 107                 if ((unsigned long)i == id) {
 108                         entry = i;
 109                         break;
 110                 }
 111         }
 112
 113         if (entry) {
 114                 list_del(&entry->list);
 115                 queue_total--;
 116         }
 117
 118         spin_unlock_bh(&queue_lock);
 119         return entry;
 120 }
 121
 122 static void
 123 __ipq_flush(ipq_cmpfn cmpfn, unsigned long data)
 124 {
 125         struct nf_queue_entry *entry, *next;
 126
 127         list_for_each_entry_safe(entry, next, &queue_list, list) {
 128                 if (!cmpfn || cmpfn(entry, data)) {
 129                         list_del(&entry->list);
 130                         queue_total--;
 131                         nf_reinject(entry, NF_DROP);
 132                 }
 133         }
 134 }
 135
 136 static void
 137 ipq_flush(ipq_cmpfn cmpfn, unsigned long data)
 138 {
 139         spin_lock_bh(&queue_lock);
 140         __ipq_flush(cmpfn, data);
 141         spin_unlock_bh(&queue_lock);
 142 }
 143
 144 static struct sk_buff *
 145 ipq_build_packet_message(struct nf_queue_entry *entry, int *errp)
 146 {
 147         sk_buff_data_t old_tail;
 148         size_t size = 0;
 149         size_t data_len = 0;
 150         struct sk_buff *skb;
 151         struct ipq_packet_msg *pmsg;
 152         struct nlmsghdr *nlh;
 153         struct timeval tv;
 154
 155         switch (ACCESS_ONCE(copy_mode)) {
 156         case IPQ_COPY_META:
 157         case IPQ_COPY_NONE:
 158                 size = NLMSG_SPACE(sizeof(*pmsg));
 159                 break;
 160
 161         case IPQ_COPY_PACKET:
 162                 if (entry->skb->ip_summed == CHECKSUM_PARTIAL &&
 163                     (*errp = skb_checksum_help(entry->skb)))
 164                         return NULL;
 165
 166                 data_len = ACCESS_ONCE(copy_range);
 167                 if (data_len == 0 || data_len > entry->skb->len)
 168                         data_len = entry->skb->len;
 169
 170                 size = NLMSG_SPACE(sizeof(*pmsg) + data_len);
 171                 break;
 172
 173         default:
 174                 *errp = -EINVAL;
 175                 return NULL;
 176         }
 177
 178         skb = alloc_skb(size, GFP_ATOMIC);
 179         if (!skb)
 180                 goto nlmsg_failure;
 181
 182         old_tail = skb->tail;
 183         nlh = NLMSG_PUT(skb, 0, 0, IPQM_PACKET, size - sizeof(*nlh));
 184         pmsg = NLMSG_DATA(nlh);
 185         memset(pmsg, 0, sizeof(*pmsg));
 186
 187         pmsg->packet_id       = (unsigned long )entry;
 188         pmsg->data_len        = data_len;
 189         tv = ktime_to_timeval(entry->skb->tstamp);
 190         pmsg->timestamp_sec   = tv.tv_sec;
 191         pmsg->timestamp_usec  = tv.tv_usec;
 192         pmsg->mark            = entry->skb->mark;
 193         pmsg->hook            = entry->hook;
 194         pmsg->hw_protocol     = entry->skb->protocol;
 195
 196         if (entry->indev)
 197                 strcpy(pmsg->indev_name, entry->indev->name);
 198         else
 199                 pmsg->indev_name[0] = '\0';
 200
 201         if (entry->outdev)
 202                 strcpy(pmsg->outdev_name, entry->outdev->name);
 203         else
 204                 pmsg->outdev_name[0] = '\0';
 205
 206         if (entry->indev && entry->skb->dev &&
 207             entry->skb->mac_header != entry->skb->network_header) {
 208                 pmsg->hw_type = entry->skb->dev->type;
 209                 pmsg->hw_addrlen = dev_parse_header(entry->skb,
 210                                                     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 "ip_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 "ip_queue: full at %d entries, "
 250                                   "dropping packets(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_ipv4(ipq_verdict_msg_t *v, struct nf_queue_entry *e)
 277 {
 278         int diff;
 279         struct iphdr *user_iph = (struct iphdr *)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 "ip_queue: error "
 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_ipv4(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         if (entry->outdev)
 378                 if (entry->outdev->ifindex == ifindex)
 379                         return 1;
 380 #ifdef CONFIG_BRIDGE_NETFILTER
 381         if (entry->skb->nf_bridge) {
 382                 if (entry->skb->nf_bridge->physindev &&
 383                     entry->skb->nf_bridge->physindev->ifindex == ifindex)
 384                         return 1;
 385                 if (entry->skb->nf_bridge->physoutdev &&
 386                     entry->skb->nf_bridge->physoutdev->ifindex == ifindex)
 387                         return 1;
 388         }
 389 #endif
 390         return 0;
 391 }
 392
 393 static void
 394 ipq_dev_drop(int ifindex)
 395 {
 396         ipq_flush(dev_cmp, ifindex);
 397 }
 398
 399 #define RCV_SKB_FAIL(err) do { netlink_ack(skb, nlh, (err)); return; } while (0)
 400
 401 static inline void
 402 __ipq_rcv_skb(struct sk_buff *skb)
 403 {
 404         int status, type, pid, flags;
 405         unsigned int nlmsglen, skblen;
 406         struct nlmsghdr *nlh;
 407         bool enable_timestamp = false;
 408
 409         skblen = skb->len;
 410         if (skblen < sizeof(*nlh))
 411                 return;
 412
 413         nlh = nlmsg_hdr(skb);
 414         nlmsglen = nlh->nlmsg_len;
 415         if (nlmsglen < sizeof(*nlh) || skblen < nlmsglen)
 416                 return;
 417
 418         pid = nlh->nlmsg_pid;
 419         flags = nlh->nlmsg_flags;
 420
 421         if(pid <= 0 || !(flags & NLM_F_REQUEST) || flags & NLM_F_MULTI)
 422                 RCV_SKB_FAIL(-EINVAL);
 423
 424         if (flags & MSG_TRUNC)
 425                 RCV_SKB_FAIL(-ECOMM);
 426
 427         type = nlh->nlmsg_type;
 428         if (type < NLMSG_NOOP || type >= IPQM_MAX)
 429                 RCV_SKB_FAIL(-EINVAL);
 430
 431         if (type <= IPQM_BASE)
 432                 return;
 433
 434         if (!capable(CAP_NET_ADMIN))
 435                 RCV_SKB_FAIL(-EPERM);
 436
 437         spin_lock_bh(&queue_lock);
 438
 439         if (peer_pid) {
 440                 if (peer_pid != pid) {
 441                         spin_unlock_bh(&queue_lock);
 442                         RCV_SKB_FAIL(-EBUSY);
 443                 }
 444         } else {
 445                 enable_timestamp = true;
 446                 peer_pid = pid;
 447         }
 448
 449         spin_unlock_bh(&queue_lock);
 450         if (enable_timestamp)
 451                 net_enable_timestamp();
 452         status = ipq_receive_peer(NLMSG_DATA(nlh), type,
 453                                   nlmsglen - NLMSG_LENGTH(0));
 454         if (status < 0)
 455                 RCV_SKB_FAIL(status);
 456
 457         if (flags & NLM_F_ACK)
 458                 netlink_ack(skb, nlh, 0);
 459 }
 460
 461 static void
 462 ipq_rcv_skb(struct sk_buff *skb)
 463 {
 464         mutex_lock(&ipqnl_mutex);
 465         __ipq_rcv_skb(skb);
 466         mutex_unlock(&ipqnl_mutex);
 467 }
 468
 469 static int
 470 ipq_rcv_dev_event(struct notifier_block *this,
 471                   unsigned long event, void *ptr)
 472 {
 473         struct net_device *dev = ptr;
 474
 475         if (!net_eq(dev_net(dev), &init_net))
 476                 return NOTIFY_DONE;
 477
 478         /* Drop any packets associated with the downed device */
 479         if (event == NETDEV_DOWN)
 480                 ipq_dev_drop(dev->ifindex);
 481         return NOTIFY_DONE;
 482 }
 483
 484 static struct notifier_block ipq_dev_notifier = {
 485         .notifier_call  = ipq_rcv_dev_event,
 486 };
 487
 488 static int
 489 ipq_rcv_nl_event(struct notifier_block *this,
 490                  unsigned long event, void *ptr)
 491 {
 492         struct netlink_notify *n = ptr;
 493
 494         if (event == NETLINK_URELEASE && n->protocol == NETLINK_FIREWALL) {
 495                 spin_lock_bh(&queue_lock);
 496                 if ((net_eq(n->net, &init_net)) && (n->pid == peer_pid))
 497                         __ipq_reset();
 498                 spin_unlock_bh(&queue_lock);
 499         }
 500         return NOTIFY_DONE;
 501 }
 502
 503 static struct notifier_block ipq_nl_notifier = {
 504         .notifier_call  = ipq_rcv_nl_event,
 505 };
 506
 507 #ifdef CONFIG_SYSCTL
 508 static struct ctl_table_header *ipq_sysctl_header;
 509
 510 static ctl_table ipq_table[] = {
 511         {
 512                 .procname       = NET_IPQ_QMAX_NAME,
 513                 .data           = &queue_maxlen,
 514                 .maxlen         = sizeof(queue_maxlen),
 515                 .mode           = 0644,
 516                 .proc_handler   = proc_dointvec
 517         },
 518         { }
 519 };
 520 #endif
 521
 522 #ifdef CONFIG_PROC_FS
 523 static int ip_queue_show(struct seq_file *m, void *v)
 524 {
 525         spin_lock_bh(&queue_lock);
 526
 527         seq_printf(m,
 528                       "Peer PID          : %d\n"
 529                       "Copy mode         : %hu\n"
 530                       "Copy range        : %u\n"
 531                       "Queue length      : %u\n"
 532                       "Queue max. length : %u\n"
 533                       "Queue dropped     : %u\n"
 534                       "Netlink dropped   : %u\n",
 535                       peer_pid,
 536                       copy_mode,
 537                       copy_range,
 538                       queue_total,
 539                       queue_maxlen,
 540                       queue_dropped,
 541                       queue_user_dropped);
 542
 543         spin_unlock_bh(&queue_lock);
 544         return 0;
 545 }
 546
 547 static int ip_queue_open(struct inode *inode, struct file *file)
 548 {
 549         return single_open(file, ip_queue_show, NULL);
 550 }
 551
 552 static const struct file_operations ip_queue_proc_fops = {
 553         .open           = ip_queue_open,
 554         .read           = seq_read,
 555         .llseek         = seq_lseek,
 556         .release        = single_release,
 557         .owner          = THIS_MODULE,
 558 };
 559 #endif
 560
 561 static const struct nf_queue_handler nfqh = {
 562         .name   = "ip_queue",
 563         .outfn  = &ipq_enqueue_packet,
 564 };
 565
 566 static int __init ip_queue_init(void)
 567 {
 568         int status = -ENOMEM;
 569         struct proc_dir_entry *proc __maybe_unused;
 570
 571         netlink_register_notifier(&ipq_nl_notifier);
 572         ipqnl = netlink_kernel_create(&init_net, NETLINK_FIREWALL, 0,
 573                                       ipq_rcv_skb, NULL, THIS_MODULE);
 574         if (ipqnl == NULL) {
 575                 printk(KERN_ERR "ip_queue: failed to create netlink socket\n");
 576                 goto cleanup_netlink_notifier;
 577         }
 578
 579 #ifdef CONFIG_PROC_FS
 580         proc = proc_create(IPQ_PROC_FS_NAME, 0, init_net.proc_net,
 581                            &ip_queue_proc_fops);
 582         if (!proc) {
 583                 printk(KERN_ERR "ip_queue: failed to create proc entry\n");
 584                 goto cleanup_ipqnl;
 585         }
 586 #endif
 587         register_netdevice_notifier(&ipq_dev_notifier);
 588 #ifdef CONFIG_SYSCTL
 589         ipq_sysctl_header = register_sysctl_paths(net_ipv4_ctl_path, ipq_table);
 590 #endif
 591         status = nf_register_queue_handler(NFPROTO_IPV4, &nfqh);
 592         if (status < 0) {
 593                 printk(KERN_ERR "ip_queue: failed to register queue handler\n");
 594                 goto cleanup_sysctl;
 595         }
 596         return status;
 597
 598 cleanup_sysctl:
 599 #ifdef CONFIG_SYSCTL
 600         unregister_sysctl_table(ipq_sysctl_header);
 601 #endif
 602         unregister_netdevice_notifier(&ipq_dev_notifier);
 603         proc_net_remove(&init_net, IPQ_PROC_FS_NAME);
 604 cleanup_ipqnl: __maybe_unused
 605         netlink_kernel_release(ipqnl);
 606         mutex_lock(&ipqnl_mutex);
 607         mutex_unlock(&ipqnl_mutex);
 608
 609 cleanup_netlink_notifier:
 610         netlink_unregister_notifier(&ipq_nl_notifier);
 611         return status;
 612 }
 613
 614 static void __exit ip_queue_fini(void)
 615 {
 616         nf_unregister_queue_handlers(&nfqh);
 617
 618         ipq_flush(NULL, 0);
 619
 620 #ifdef CONFIG_SYSCTL
 621         unregister_sysctl_table(ipq_sysctl_header);
 622 #endif
 623         unregister_netdevice_notifier(&ipq_dev_notifier);
 624         proc_net_remove(&init_net, IPQ_PROC_FS_NAME);
 625
 626         netlink_kernel_release(ipqnl);
 627         mutex_lock(&ipqnl_mutex);
 628         mutex_unlock(&ipqnl_mutex);
 629
 630         netlink_unregister_notifier(&ipq_nl_notifier);
 631 }
 632
 633 MODULE_DESCRIPTION("IPv4 packet queue handler");
 634 MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");
 635 MODULE_LICENSE("GPL");
 636 MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_FIREWALL);
 637
 638 module_init(ip_queue_init);
 639 module_exit(ip_queue_fini);