net/core/drop_monitor.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Monitoring code for network dropped packet alerts
   4  *
   5  * Copyright (C) 2009 Neil Horman <nhorman@tuxdriver.com>
   6  */
   7
   8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
   9
  10 #include <linux/netdevice.h>
  11 #include <linux/etherdevice.h>
  12 #include <linux/string.h>
  13 #include <linux/if_arp.h>
  14 #include <linux/inetdevice.h>
  15 #include <linux/inet.h>
  16 #include <linux/interrupt.h>
  17 #include <linux/netpoll.h>
  18 #include <linux/sched.h>
  19 #include <linux/delay.h>
  20 #include <linux/types.h>
  21 #include <linux/workqueue.h>
  22 #include <linux/netlink.h>
  23 #include <linux/net_dropmon.h>
  24 #include <linux/percpu.h>
  25 #include <linux/timer.h>
  26 #include <linux/bitops.h>
  27 #include <linux/slab.h>
  28 #include <linux/module.h>
  29 #include <net/drop_monitor.h>
  30 #include <net/genetlink.h>
  31 #include <net/netevent.h>
  32
  33 #include <trace/events/skb.h>
  34 #include <trace/events/napi.h>
  35
  36 #include <asm/unaligned.h>
  37
  38 #define TRACE_ON 1
  39 #define TRACE_OFF 0
  40
  41 /*
  42  * Globals, our netlink socket pointer
  43  * and the work handle that will send up
  44  * netlink alerts
  45  */
  46 static int trace_state = TRACE_OFF;
  47 static bool monitor_hw;
  48
  49 /* net_dm_mutex
  50  *
  51  * An overall lock guarding every operation coming from userspace.
  52  * It also guards the global 'hw_stats_list' list.
  53  */
  54 static DEFINE_MUTEX(net_dm_mutex);
  55
  56 struct net_dm_stats {
  57         u64 dropped;
  58         struct u64_stats_sync syncp;
  59 };
  60
  61 #define NET_DM_MAX_HW_TRAP_NAME_LEN 40
  62
  63 struct net_dm_hw_entry {
  64         char trap_name[NET_DM_MAX_HW_TRAP_NAME_LEN];
  65         u32 count;
  66 };
  67
  68 struct net_dm_hw_entries {
  69         u32 num_entries;
  70         struct net_dm_hw_entry entries[0];
  71 };
  72
  73 struct per_cpu_dm_data {
  74         spinlock_t              lock;   /* Protects 'skb', 'hw_entries' and
  75                                          * 'send_timer'
  76                                          */
  77         union {
  78                 struct sk_buff                  *skb;
  79                 struct net_dm_hw_entries        *hw_entries;
  80         };
  81         struct sk_buff_head     drop_queue;
  82         struct work_struct      dm_alert_work;
  83         struct timer_list       send_timer;
  84         struct net_dm_stats     stats;
  85 };
  86
  87 struct dm_hw_stat_delta {
  88         struct net_device *dev;
  89         unsigned long last_rx;
  90         struct list_head list;
  91         struct rcu_head rcu;
  92         unsigned long last_drop_val;
  93 };
  94
  95 static struct genl_family net_drop_monitor_family;
  96
  97 static DEFINE_PER_CPU(struct per_cpu_dm_data, dm_cpu_data);
  98 static DEFINE_PER_CPU(struct per_cpu_dm_data, dm_hw_cpu_data);
  99
 100 static int dm_hit_limit = 64;
 101 static int dm_delay = 1;
 102 static unsigned long dm_hw_check_delta = 2*HZ;
 103 static LIST_HEAD(hw_stats_list);
 104
 105 static enum net_dm_alert_mode net_dm_alert_mode = NET_DM_ALERT_MODE_SUMMARY;
 106 static u32 net_dm_trunc_len;
 107 static u32 net_dm_queue_len = 1000;
 108
 109 struct net_dm_alert_ops {
 110         void (*kfree_skb_probe)(void *ignore, struct sk_buff *skb,
 111                                 void *location);
 112         void (*napi_poll_probe)(void *ignore, struct napi_struct *napi,
 113                                 int work, int budget);
 114         void (*work_item_func)(struct work_struct *work);
 115         void (*hw_work_item_func)(struct work_struct *work);
 116         void (*hw_probe)(struct sk_buff *skb,
 117                          const struct net_dm_hw_metadata *hw_metadata);
 118 };
 119
 120 struct net_dm_skb_cb {
 121         union {
 122                 struct net_dm_hw_metadata *hw_metadata;
 123                 void *pc;
 124         };
 125 };
 126
 127 #define NET_DM_SKB_CB(__skb) ((struct net_dm_skb_cb *)&((__skb)->cb[0]))
 128
 129 static struct sk_buff *reset_per_cpu_data(struct per_cpu_dm_data *data)
 130 {
 131         size_t al;
 132         struct net_dm_alert_msg *msg;
 133         struct nlattr *nla;
 134         struct sk_buff *skb;
 135         unsigned long flags;
 136         void *msg_header;
 137
 138         al = sizeof(struct net_dm_alert_msg);
 139         al += dm_hit_limit * sizeof(struct net_dm_drop_point);
 140         al += sizeof(struct nlattr);
 141
 142         skb = genlmsg_new(al, GFP_KERNEL);
 143
 144         if (!skb)
 145                 goto err;
 146
 147         msg_header = genlmsg_put(skb, 0, 0, &net_drop_monitor_family,
 148                                  0, NET_DM_CMD_ALERT);
 149         if (!msg_header) {
 150                 nlmsg_free(skb);
 151                 skb = NULL;
 152                 goto err;
 153         }
 154         nla = nla_reserve(skb, NLA_UNSPEC,
 155                           sizeof(struct net_dm_alert_msg));
 156         if (!nla) {
 157                 nlmsg_free(skb);
 158                 skb = NULL;
 159                 goto err;
 160         }
 161         msg = nla_data(nla);
 162         memset(msg, 0, al);
 163         goto out;
 164
 165 err:
 166         mod_timer(&data->send_timer, jiffies + HZ / 10);
 167 out:
 168         spin_lock_irqsave(&data->lock, flags);
 169         swap(data->skb, skb);
 170         spin_unlock_irqrestore(&data->lock, flags);
 171
 172         if (skb) {
 173                 struct nlmsghdr *nlh = (struct nlmsghdr *)skb->data;
 174                 struct genlmsghdr *gnlh = (struct genlmsghdr *)nlmsg_data(nlh);
 175
 176                 genlmsg_end(skb, genlmsg_data(gnlh));
 177         }
 178
 179         return skb;
 180 }
 181
 182 static const struct genl_multicast_group dropmon_mcgrps[] = {
 183         { .name = "events", },
 184 };
 185
 186 static void send_dm_alert(struct work_struct *work)
 187 {
 188         struct sk_buff *skb;
 189         struct per_cpu_dm_data *data;
 190
 191         data = container_of(work, struct per_cpu_dm_data, dm_alert_work);
 192
 193         skb = reset_per_cpu_data(data);
 194
 195         if (skb)
 196                 genlmsg_multicast(&net_drop_monitor_family, skb, 0,
 197                                   0, GFP_KERNEL);
 198 }
 199
 200 /*
 201  * This is the timer function to delay the sending of an alert
 202  * in the event that more drops will arrive during the
 203  * hysteresis period.
 204  */
 205 static void sched_send_work(struct timer_list *t)
 206 {
 207         struct per_cpu_dm_data *data = from_timer(data, t, send_timer);
 208
 209         schedule_work(&data->dm_alert_work);
 210 }
 211
 212 static void trace_drop_common(struct sk_buff *skb, void *location)
 213 {
 214         struct net_dm_alert_msg *msg;
 215         struct nlmsghdr *nlh;
 216         struct nlattr *nla;
 217         int i;
 218         struct sk_buff *dskb;
 219         struct per_cpu_dm_data *data;
 220         unsigned long flags;
 221
 222         local_irq_save(flags);
 223         data = this_cpu_ptr(&dm_cpu_data);
 224         spin_lock(&data->lock);
 225         dskb = data->skb;
 226
 227         if (!dskb)
 228                 goto out;
 229
 230         nlh = (struct nlmsghdr *)dskb->data;
 231         nla = genlmsg_data(nlmsg_data(nlh));
 232         msg = nla_data(nla);
 233         for (i = 0; i < msg->entries; i++) {
 234                 if (!memcmp(&location, msg->points[i].pc, sizeof(void *))) {
 235                         msg->points[i].count++;
 236                         goto out;
 237                 }
 238         }
 239         if (msg->entries == dm_hit_limit)
 240                 goto out;
 241         /*
 242          * We need to create a new entry
 243          */
 244         __nla_reserve_nohdr(dskb, sizeof(struct net_dm_drop_point));
 245         nla->nla_len += NLA_ALIGN(sizeof(struct net_dm_drop_point));
 246         memcpy(msg->points[msg->entries].pc, &location, sizeof(void *));
 247         msg->points[msg->entries].count = 1;
 248         msg->entries++;
 249
 250         if (!timer_pending(&data->send_timer)) {
 251                 data->send_timer.expires = jiffies + dm_delay * HZ;
 252                 add_timer(&data->send_timer);
 253         }
 254
 255 out:
 256         spin_unlock_irqrestore(&data->lock, flags);
 257 }
 258
 259 static void trace_kfree_skb_hit(void *ignore, struct sk_buff *skb, void *location)
 260 {
 261         trace_drop_common(skb, location);
 262 }
 263
 264 static void trace_napi_poll_hit(void *ignore, struct napi_struct *napi,
 265                                 int work, int budget)
 266 {
 267         struct dm_hw_stat_delta *new_stat;
 268
 269         /*
 270          * Don't check napi structures with no associated device
 271          */
 272         if (!napi->dev)
 273                 return;
 274
 275         rcu_read_lock();
 276         list_for_each_entry_rcu(new_stat, &hw_stats_list, list) {
 277                 /*
 278                  * only add a note to our monitor buffer if:
 279                  * 1) this is the dev we received on
 280                  * 2) its after the last_rx delta
 281                  * 3) our rx_dropped count has gone up
 282                  */
 283                 if ((new_stat->dev == napi->dev)  &&
 284                     (time_after(jiffies, new_stat->last_rx + dm_hw_check_delta)) &&
 285                     (napi->dev->stats.rx_dropped != new_stat->last_drop_val)) {
 286                         trace_drop_common(NULL, NULL);
 287                         new_stat->last_drop_val = napi->dev->stats.rx_dropped;
 288                         new_stat->last_rx = jiffies;
 289                         break;
 290                 }
 291         }
 292         rcu_read_unlock();
 293 }
 294
 295 static struct net_dm_hw_entries *
 296 net_dm_hw_reset_per_cpu_data(struct per_cpu_dm_data *hw_data)
 297 {
 298         struct net_dm_hw_entries *hw_entries;
 299         unsigned long flags;
 300
 301         hw_entries = kzalloc(struct_size(hw_entries, entries, dm_hit_limit),
 302                              GFP_KERNEL);
 303         if (!hw_entries) {
 304                 /* If the memory allocation failed, we try to perform another
 305                  * allocation in 1/10 second. Otherwise, the probe function
 306                  * will constantly bail out.
 307                  */
 308                 mod_timer(&hw_data->send_timer, jiffies + HZ / 10);
 309         }
 310
 311         spin_lock_irqsave(&hw_data->lock, flags);
 312         swap(hw_data->hw_entries, hw_entries);
 313         spin_unlock_irqrestore(&hw_data->lock, flags);
 314
 315         return hw_entries;
 316 }
 317
 318 static int net_dm_hw_entry_put(struct sk_buff *msg,
 319                                const struct net_dm_hw_entry *hw_entry)
 320 {
 321         struct nlattr *attr;
 322
 323         attr = nla_nest_start(msg, NET_DM_ATTR_HW_ENTRY);
 324         if (!attr)
 325                 return -EMSGSIZE;
 326
 327         if (nla_put_string(msg, NET_DM_ATTR_HW_TRAP_NAME, hw_entry->trap_name))
 328                 goto nla_put_failure;
 329
 330         if (nla_put_u32(msg, NET_DM_ATTR_HW_TRAP_COUNT, hw_entry->count))
 331                 goto nla_put_failure;
 332
 333         nla_nest_end(msg, attr);
 334
 335         return 0;
 336
 337 nla_put_failure:
 338         nla_nest_cancel(msg, attr);
 339         return -EMSGSIZE;
 340 }
 341
 342 static int net_dm_hw_entries_put(struct sk_buff *msg,
 343                                  const struct net_dm_hw_entries *hw_entries)
 344 {
 345         struct nlattr *attr;
 346         int i;
 347
 348         attr = nla_nest_start(msg, NET_DM_ATTR_HW_ENTRIES);
 349         if (!attr)
 350                 return -EMSGSIZE;
 351
 352         for (i = 0; i < hw_entries->num_entries; i++) {
 353                 int rc;
 354
 355                 rc = net_dm_hw_entry_put(msg, &hw_entries->entries[i]);
 356                 if (rc)
 357                         goto nla_put_failure;
 358         }
 359
 360         nla_nest_end(msg, attr);
 361
 362         return 0;
 363
 364 nla_put_failure:
 365         nla_nest_cancel(msg, attr);
 366         return -EMSGSIZE;
 367 }
 368
 369 static int
 370 net_dm_hw_summary_report_fill(struct sk_buff *msg,
 371                               const struct net_dm_hw_entries *hw_entries)
 372 {
 373         struct net_dm_alert_msg anc_hdr = { 0 };
 374         void *hdr;
 375         int rc;
 376
 377         hdr = genlmsg_put(msg, 0, 0, &net_drop_monitor_family, 0,
 378                           NET_DM_CMD_ALERT);
 379         if (!hdr)
 380                 return -EMSGSIZE;
 381
 382         /* We need to put the ancillary header in order not to break user
 383          * space.
 384          */
 385         if (nla_put(msg, NLA_UNSPEC, sizeof(anc_hdr), &anc_hdr))
 386                 goto nla_put_failure;
 387
 388         rc = net_dm_hw_entries_put(msg, hw_entries);
 389         if (rc)
 390                 goto nla_put_failure;
 391
 392         genlmsg_end(msg, hdr);
 393
 394         return 0;
 395
 396 nla_put_failure:
 397         genlmsg_cancel(msg, hdr);
 398         return -EMSGSIZE;
 399 }
 400
 401 static void net_dm_hw_summary_work(struct work_struct *work)
 402 {
 403         struct net_dm_hw_entries *hw_entries;
 404         struct per_cpu_dm_data *hw_data;
 405         struct sk_buff *msg;
 406         int rc;
 407
 408         hw_data = container_of(work, struct per_cpu_dm_data, dm_alert_work);
 409
 410         hw_entries = net_dm_hw_reset_per_cpu_data(hw_data);
 411         if (!hw_entries)
 412                 return;
 413
 414         msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 415         if (!msg)
 416                 goto out;
 417
 418         rc = net_dm_hw_summary_report_fill(msg, hw_entries);
 419         if (rc) {
 420                 nlmsg_free(msg);
 421                 goto out;
 422         }
 423
 424         genlmsg_multicast(&net_drop_monitor_family, msg, 0, 0, GFP_KERNEL);
 425
 426 out:
 427         kfree(hw_entries);
 428 }
 429
 430 static void
 431 net_dm_hw_summary_probe(struct sk_buff *skb,
 432                         const struct net_dm_hw_metadata *hw_metadata)
 433 {
 434         struct net_dm_hw_entries *hw_entries;
 435         struct net_dm_hw_entry *hw_entry;
 436         struct per_cpu_dm_data *hw_data;
 437         unsigned long flags;
 438         int i;
 439
 440         hw_data = this_cpu_ptr(&dm_hw_cpu_data);
 441         spin_lock_irqsave(&hw_data->lock, flags);
 442         hw_entries = hw_data->hw_entries;
 443
 444         if (!hw_entries)
 445                 goto out;
 446
 447         for (i = 0; i < hw_entries->num_entries; i++) {
 448                 hw_entry = &hw_entries->entries[i];
 449                 if (!strncmp(hw_entry->trap_name, hw_metadata->trap_name,
 450                              NET_DM_MAX_HW_TRAP_NAME_LEN - 1)) {
 451                         hw_entry->count++;
 452                         goto out;
 453                 }
 454         }
 455         if (WARN_ON_ONCE(hw_entries->num_entries == dm_hit_limit))
 456                 goto out;
 457
 458         hw_entry = &hw_entries->entries[hw_entries->num_entries];
 459         strlcpy(hw_entry->trap_name, hw_metadata->trap_name,
 460                 NET_DM_MAX_HW_TRAP_NAME_LEN - 1);
 461         hw_entry->count = 1;
 462         hw_entries->num_entries++;
 463
 464         if (!timer_pending(&hw_data->send_timer)) {
 465                 hw_data->send_timer.expires = jiffies + dm_delay * HZ;
 466                 add_timer(&hw_data->send_timer);
 467         }
 468
 469 out:
 470         spin_unlock_irqrestore(&hw_data->lock, flags);
 471 }
 472
 473 static const struct net_dm_alert_ops net_dm_alert_summary_ops = {
 474         .kfree_skb_probe        = trace_kfree_skb_hit,
 475         .napi_poll_probe        = trace_napi_poll_hit,
 476         .work_item_func         = send_dm_alert,
 477         .hw_work_item_func      = net_dm_hw_summary_work,
 478         .hw_probe               = net_dm_hw_summary_probe,
 479 };
 480
 481 static void net_dm_packet_trace_kfree_skb_hit(void *ignore,
 482                                               struct sk_buff *skb,
 483                                               void *location)
 484 {
 485         ktime_t tstamp = ktime_get_real();
 486         struct per_cpu_dm_data *data;
 487         struct sk_buff *nskb;
 488         unsigned long flags;
 489
 490         if (!skb_mac_header_was_set(skb))
 491                 return;
 492
 493         nskb = skb_clone(skb, GFP_ATOMIC);
 494         if (!nskb)
 495                 return;
 496
 497         NET_DM_SKB_CB(nskb)->pc = location;
 498         /* Override the timestamp because we care about the time when the
 499          * packet was dropped.
 500          */
 501         nskb->tstamp = tstamp;
 502
 503         data = this_cpu_ptr(&dm_cpu_data);
 504
 505         spin_lock_irqsave(&data->drop_queue.lock, flags);
 506         if (skb_queue_len(&data->drop_queue) < net_dm_queue_len)
 507                 __skb_queue_tail(&data->drop_queue, nskb);
 508         else
 509                 goto unlock_free;
 510         spin_unlock_irqrestore(&data->drop_queue.lock, flags);
 511
 512         schedule_work(&data->dm_alert_work);
 513
 514         return;
 515
 516 unlock_free:
 517         spin_unlock_irqrestore(&data->drop_queue.lock, flags);
 518         u64_stats_update_begin(&data->stats.syncp);
 519         data->stats.dropped++;
 520         u64_stats_update_end(&data->stats.syncp);
 521         consume_skb(nskb);
 522 }
 523
 524 static void net_dm_packet_trace_napi_poll_hit(void *ignore,
 525                                               struct napi_struct *napi,
 526                                               int work, int budget)
 527 {
 528 }
 529
 530 static size_t net_dm_in_port_size(void)
 531 {
 532                /* NET_DM_ATTR_IN_PORT nest */
 533         return nla_total_size(0) +
 534                /* NET_DM_ATTR_PORT_NETDEV_IFINDEX */
 535                nla_total_size(sizeof(u32)) +
 536                /* NET_DM_ATTR_PORT_NETDEV_NAME */
 537                nla_total_size(IFNAMSIZ + 1);
 538 }
 539
 540 #define NET_DM_MAX_SYMBOL_LEN 40
 541
 542 static size_t net_dm_packet_report_size(size_t payload_len)
 543 {
 544         size_t size;
 545
 546         size = nlmsg_msg_size(GENL_HDRLEN + net_drop_monitor_family.hdrsize);
 547
 548         return NLMSG_ALIGN(size) +
 549                /* NET_DM_ATTR_ORIGIN */
 550                nla_total_size(sizeof(u16)) +
 551                /* NET_DM_ATTR_PC */
 552                nla_total_size(sizeof(u64)) +
 553                /* NET_DM_ATTR_SYMBOL */
 554                nla_total_size(NET_DM_MAX_SYMBOL_LEN + 1) +
 555                /* NET_DM_ATTR_IN_PORT */
 556                net_dm_in_port_size() +
 557                /* NET_DM_ATTR_TIMESTAMP */
 558                nla_total_size(sizeof(u64)) +
 559                /* NET_DM_ATTR_ORIG_LEN */
 560                nla_total_size(sizeof(u32)) +
 561                /* NET_DM_ATTR_PROTO */
 562                nla_total_size(sizeof(u16)) +
 563                /* NET_DM_ATTR_PAYLOAD */
 564                nla_total_size(payload_len);
 565 }
 566
 567 static int net_dm_packet_report_in_port_put(struct sk_buff *msg, int ifindex,
 568                                             const char *name)
 569 {
 570         struct nlattr *attr;
 571
 572         attr = nla_nest_start(msg, NET_DM_ATTR_IN_PORT);
 573         if (!attr)
 574                 return -EMSGSIZE;
 575
 576         if (ifindex &&
 577             nla_put_u32(msg, NET_DM_ATTR_PORT_NETDEV_IFINDEX, ifindex))
 578                 goto nla_put_failure;
 579
 580         if (name && nla_put_string(msg, NET_DM_ATTR_PORT_NETDEV_NAME, name))
 581                 goto nla_put_failure;
 582
 583         nla_nest_end(msg, attr);
 584
 585         return 0;
 586
 587 nla_put_failure:
 588         nla_nest_cancel(msg, attr);
 589         return -EMSGSIZE;
 590 }
 591
 592 static int net_dm_packet_report_fill(struct sk_buff *msg, struct sk_buff *skb,
 593                                      size_t payload_len)
 594 {
 595         u64 pc = (u64)(uintptr_t) NET_DM_SKB_CB(skb)->pc;
 596         char buf[NET_DM_MAX_SYMBOL_LEN];
 597         struct nlattr *attr;
 598         void *hdr;
 599         int rc;
 600
 601         hdr = genlmsg_put(msg, 0, 0, &net_drop_monitor_family, 0,
 602                           NET_DM_CMD_PACKET_ALERT);
 603         if (!hdr)
 604                 return -EMSGSIZE;
 605
 606         if (nla_put_u16(msg, NET_DM_ATTR_ORIGIN, NET_DM_ORIGIN_SW))
 607                 goto nla_put_failure;
 608
 609         if (nla_put_u64_64bit(msg, NET_DM_ATTR_PC, pc, NET_DM_ATTR_PAD))
 610                 goto nla_put_failure;
 611
 612         snprintf(buf, sizeof(buf), "%pS", NET_DM_SKB_CB(skb)->pc);
 613         if (nla_put_string(msg, NET_DM_ATTR_SYMBOL, buf))
 614                 goto nla_put_failure;
 615
 616         rc = net_dm_packet_report_in_port_put(msg, skb->skb_iif, NULL);
 617         if (rc)
 618                 goto nla_put_failure;
 619
 620         if (nla_put_u64_64bit(msg, NET_DM_ATTR_TIMESTAMP,
 621                               ktime_to_ns(skb->tstamp), NET_DM_ATTR_PAD))
 622                 goto nla_put_failure;
 623
 624         if (nla_put_u32(msg, NET_DM_ATTR_ORIG_LEN, skb->len))
 625                 goto nla_put_failure;
 626
 627         if (!payload_len)
 628                 goto out;
 629
 630         if (nla_put_u16(msg, NET_DM_ATTR_PROTO, be16_to_cpu(skb->protocol)))
 631                 goto nla_put_failure;
 632
 633         attr = skb_put(msg, nla_total_size(payload_len));
 634         attr->nla_type = NET_DM_ATTR_PAYLOAD;
 635         attr->nla_len = nla_attr_size(payload_len);
 636         if (skb_copy_bits(skb, 0, nla_data(attr), payload_len))
 637                 goto nla_put_failure;
 638
 639 out:
 640         genlmsg_end(msg, hdr);
 641
 642         return 0;
 643
 644 nla_put_failure:
 645         genlmsg_cancel(msg, hdr);
 646         return -EMSGSIZE;
 647 }
 648
 649 #define NET_DM_MAX_PACKET_SIZE (0xffff - NLA_HDRLEN - NLA_ALIGNTO)
 650
 651 static void net_dm_packet_report(struct sk_buff *skb)
 652 {
 653         struct sk_buff *msg;
 654         size_t payload_len;
 655         int rc;
 656
 657         /* Make sure we start copying the packet from the MAC header */
 658         if (skb->data > skb_mac_header(skb))
 659                 skb_push(skb, skb->data - skb_mac_header(skb));
 660         else
 661                 skb_pull(skb, skb_mac_header(skb) - skb->data);
 662
 663         /* Ensure packet fits inside a single netlink attribute */
 664         payload_len = min_t(size_t, skb->len, NET_DM_MAX_PACKET_SIZE);
 665         if (net_dm_trunc_len)
 666                 payload_len = min_t(size_t, net_dm_trunc_len, payload_len);
 667
 668         msg = nlmsg_new(net_dm_packet_report_size(payload_len), GFP_KERNEL);
 669         if (!msg)
 670                 goto out;
 671
 672         rc = net_dm_packet_report_fill(msg, skb, payload_len);
 673         if (rc) {
 674                 nlmsg_free(msg);
 675                 goto out;
 676         }
 677
 678         genlmsg_multicast(&net_drop_monitor_family, msg, 0, 0, GFP_KERNEL);
 679
 680 out:
 681         consume_skb(skb);
 682 }
 683
 684 static void net_dm_packet_work(struct work_struct *work)
 685 {
 686         struct per_cpu_dm_data *data;
 687         struct sk_buff_head list;
 688         struct sk_buff *skb;
 689         unsigned long flags;
 690
 691         data = container_of(work, struct per_cpu_dm_data, dm_alert_work);
 692
 693         __skb_queue_head_init(&list);
 694
 695         spin_lock_irqsave(&data->drop_queue.lock, flags);
 696         skb_queue_splice_tail_init(&data->drop_queue, &list);
 697         spin_unlock_irqrestore(&data->drop_queue.lock, flags);
 698
 699         while ((skb = __skb_dequeue(&list)))
 700                 net_dm_packet_report(skb);
 701 }
 702
 703 static size_t
 704 net_dm_hw_packet_report_size(size_t payload_len,
 705                              const struct net_dm_hw_metadata *hw_metadata)
 706 {
 707         size_t size;
 708
 709         size = nlmsg_msg_size(GENL_HDRLEN + net_drop_monitor_family.hdrsize);
 710
 711         return NLMSG_ALIGN(size) +
 712                /* NET_DM_ATTR_ORIGIN */
 713                nla_total_size(sizeof(u16)) +
 714                /* NET_DM_ATTR_HW_TRAP_GROUP_NAME */
 715                nla_total_size(strlen(hw_metadata->trap_group_name) + 1) +
 716                /* NET_DM_ATTR_HW_TRAP_NAME */
 717                nla_total_size(strlen(hw_metadata->trap_name) + 1) +
 718                /* NET_DM_ATTR_IN_PORT */
 719                net_dm_in_port_size() +
 720                /* NET_DM_ATTR_TIMESTAMP */
 721                nla_total_size(sizeof(u64)) +
 722                /* NET_DM_ATTR_ORIG_LEN */
 723                nla_total_size(sizeof(u32)) +
 724                /* NET_DM_ATTR_PROTO */
 725                nla_total_size(sizeof(u16)) +
 726                /* NET_DM_ATTR_PAYLOAD */
 727                nla_total_size(payload_len);
 728 }
 729
 730 static int net_dm_hw_packet_report_fill(struct sk_buff *msg,
 731                                         struct sk_buff *skb, size_t payload_len)
 732 {
 733         struct net_dm_hw_metadata *hw_metadata;
 734         struct nlattr *attr;
 735         void *hdr;
 736
 737         hw_metadata = NET_DM_SKB_CB(skb)->hw_metadata;
 738
 739         hdr = genlmsg_put(msg, 0, 0, &net_drop_monitor_family, 0,
 740                           NET_DM_CMD_PACKET_ALERT);
 741         if (!hdr)
 742                 return -EMSGSIZE;
 743
 744         if (nla_put_u16(msg, NET_DM_ATTR_ORIGIN, NET_DM_ORIGIN_HW))
 745                 goto nla_put_failure;
 746
 747         if (nla_put_string(msg, NET_DM_ATTR_HW_TRAP_GROUP_NAME,
 748                            hw_metadata->trap_group_name))
 749                 goto nla_put_failure;
 750
 751         if (nla_put_string(msg, NET_DM_ATTR_HW_TRAP_NAME,
 752                            hw_metadata->trap_name))
 753                 goto nla_put_failure;
 754
 755         if (hw_metadata->input_dev) {
 756                 struct net_device *dev = hw_metadata->input_dev;
 757                 int rc;
 758
 759                 rc = net_dm_packet_report_in_port_put(msg, dev->ifindex,
 760                                                       dev->name);
 761                 if (rc)
 762                         goto nla_put_failure;
 763         }
 764
 765         if (nla_put_u64_64bit(msg, NET_DM_ATTR_TIMESTAMP,
 766                               ktime_to_ns(skb->tstamp), NET_DM_ATTR_PAD))
 767                 goto nla_put_failure;
 768
 769         if (nla_put_u32(msg, NET_DM_ATTR_ORIG_LEN, skb->len))
 770                 goto nla_put_failure;
 771
 772         if (!payload_len)
 773                 goto out;
 774
 775         if (nla_put_u16(msg, NET_DM_ATTR_PROTO, be16_to_cpu(skb->protocol)))
 776                 goto nla_put_failure;
 777
 778         attr = skb_put(msg, nla_total_size(payload_len));
 779         attr->nla_type = NET_DM_ATTR_PAYLOAD;
 780         attr->nla_len = nla_attr_size(payload_len);
 781         if (skb_copy_bits(skb, 0, nla_data(attr), payload_len))
 782                 goto nla_put_failure;
 783
 784 out:
 785         genlmsg_end(msg, hdr);
 786
 787         return 0;
 788
 789 nla_put_failure:
 790         genlmsg_cancel(msg, hdr);
 791         return -EMSGSIZE;
 792 }
 793
 794 static struct net_dm_hw_metadata *
 795 net_dm_hw_metadata_clone(const struct net_dm_hw_metadata *hw_metadata)
 796 {
 797         struct net_dm_hw_metadata *n_hw_metadata;
 798         const char *trap_group_name;
 799         const char *trap_name;
 800
 801         n_hw_metadata = kmalloc(sizeof(*hw_metadata), GFP_ATOMIC);
 802         if (!n_hw_metadata)
 803                 return NULL;
 804
 805         trap_group_name = kstrdup(hw_metadata->trap_group_name, GFP_ATOMIC);
 806         if (!trap_group_name)
 807                 goto free_hw_metadata;
 808         n_hw_metadata->trap_group_name = trap_group_name;
 809
 810         trap_name = kstrdup(hw_metadata->trap_name, GFP_ATOMIC);
 811         if (!trap_name)
 812                 goto free_trap_group;
 813         n_hw_metadata->trap_name = trap_name;
 814
 815         n_hw_metadata->input_dev = hw_metadata->input_dev;
 816         if (n_hw_metadata->input_dev)
 817                 dev_hold(n_hw_metadata->input_dev);
 818
 819         return n_hw_metadata;
 820
 821 free_trap_group:
 822         kfree(trap_group_name);
 823 free_hw_metadata:
 824         kfree(n_hw_metadata);
 825         return NULL;
 826 }
 827
 828 static void
 829 net_dm_hw_metadata_free(const struct net_dm_hw_metadata *hw_metadata)
 830 {
 831         if (hw_metadata->input_dev)
 832                 dev_put(hw_metadata->input_dev);
 833         kfree(hw_metadata->trap_name);
 834         kfree(hw_metadata->trap_group_name);
 835         kfree(hw_metadata);
 836 }
 837
 838 static void net_dm_hw_packet_report(struct sk_buff *skb)
 839 {
 840         struct net_dm_hw_metadata *hw_metadata;
 841         struct sk_buff *msg;
 842         size_t payload_len;
 843         int rc;
 844
 845         if (skb->data > skb_mac_header(skb))
 846                 skb_push(skb, skb->data - skb_mac_header(skb));
 847         else
 848                 skb_pull(skb, skb_mac_header(skb) - skb->data);
 849
 850         payload_len = min_t(size_t, skb->len, NET_DM_MAX_PACKET_SIZE);
 851         if (net_dm_trunc_len)
 852                 payload_len = min_t(size_t, net_dm_trunc_len, payload_len);
 853
 854         hw_metadata = NET_DM_SKB_CB(skb)->hw_metadata;
 855         msg = nlmsg_new(net_dm_hw_packet_report_size(payload_len, hw_metadata),
 856                         GFP_KERNEL);
 857         if (!msg)
 858                 goto out;
 859
 860         rc = net_dm_hw_packet_report_fill(msg, skb, payload_len);
 861         if (rc) {
 862                 nlmsg_free(msg);
 863                 goto out;
 864         }
 865
 866         genlmsg_multicast(&net_drop_monitor_family, msg, 0, 0, GFP_KERNEL);
 867
 868 out:
 869         net_dm_hw_metadata_free(NET_DM_SKB_CB(skb)->hw_metadata);
 870         consume_skb(skb);
 871 }
 872
 873 static void net_dm_hw_packet_work(struct work_struct *work)
 874 {
 875         struct per_cpu_dm_data *hw_data;
 876         struct sk_buff_head list;
 877         struct sk_buff *skb;
 878         unsigned long flags;
 879
 880         hw_data = container_of(work, struct per_cpu_dm_data, dm_alert_work);
 881
 882         __skb_queue_head_init(&list);
 883
 884         spin_lock_irqsave(&hw_data->drop_queue.lock, flags);
 885         skb_queue_splice_tail_init(&hw_data->drop_queue, &list);
 886         spin_unlock_irqrestore(&hw_data->drop_queue.lock, flags);
 887
 888         while ((skb = __skb_dequeue(&list)))
 889                 net_dm_hw_packet_report(skb);
 890 }
 891
 892 static void
 893 net_dm_hw_packet_probe(struct sk_buff *skb,
 894                        const struct net_dm_hw_metadata *hw_metadata)
 895 {
 896         struct net_dm_hw_metadata *n_hw_metadata;
 897         ktime_t tstamp = ktime_get_real();
 898         struct per_cpu_dm_data *hw_data;
 899         struct sk_buff *nskb;
 900         unsigned long flags;
 901
 902         if (!skb_mac_header_was_set(skb))
 903                 return;
 904
 905         nskb = skb_clone(skb, GFP_ATOMIC);
 906         if (!nskb)
 907                 return;
 908
 909         n_hw_metadata = net_dm_hw_metadata_clone(hw_metadata);
 910         if (!n_hw_metadata)
 911                 goto free;
 912
 913         NET_DM_SKB_CB(nskb)->hw_metadata = n_hw_metadata;
 914         nskb->tstamp = tstamp;
 915
 916         hw_data = this_cpu_ptr(&dm_hw_cpu_data);
 917
 918         spin_lock_irqsave(&hw_data->drop_queue.lock, flags);
 919         if (skb_queue_len(&hw_data->drop_queue) < net_dm_queue_len)
 920                 __skb_queue_tail(&hw_data->drop_queue, nskb);
 921         else
 922                 goto unlock_free;
 923         spin_unlock_irqrestore(&hw_data->drop_queue.lock, flags);
 924
 925         schedule_work(&hw_data->dm_alert_work);
 926
 927         return;
 928
 929 unlock_free:
 930         spin_unlock_irqrestore(&hw_data->drop_queue.lock, flags);
 931         u64_stats_update_begin(&hw_data->stats.syncp);
 932         hw_data->stats.dropped++;
 933         u64_stats_update_end(&hw_data->stats.syncp);
 934         net_dm_hw_metadata_free(n_hw_metadata);
 935 free:
 936         consume_skb(nskb);
 937 }
 938
 939 static const struct net_dm_alert_ops net_dm_alert_packet_ops = {
 940         .kfree_skb_probe        = net_dm_packet_trace_kfree_skb_hit,
 941         .napi_poll_probe        = net_dm_packet_trace_napi_poll_hit,
 942         .work_item_func         = net_dm_packet_work,
 943         .hw_work_item_func      = net_dm_hw_packet_work,
 944         .hw_probe               = net_dm_hw_packet_probe,
 945 };
 946
 947 static const struct net_dm_alert_ops *net_dm_alert_ops_arr[] = {
 948         [NET_DM_ALERT_MODE_SUMMARY]     = &net_dm_alert_summary_ops,
 949         [NET_DM_ALERT_MODE_PACKET]      = &net_dm_alert_packet_ops,
 950 };
 951
 952 void net_dm_hw_report(struct sk_buff *skb,
 953                       const struct net_dm_hw_metadata *hw_metadata)
 954 {
 955         rcu_read_lock();
 956
 957         if (!monitor_hw)
 958                 goto out;
 959
 960         net_dm_alert_ops_arr[net_dm_alert_mode]->hw_probe(skb, hw_metadata);
 961
 962 out:
 963         rcu_read_unlock();
 964 }
 965 EXPORT_SYMBOL_GPL(net_dm_hw_report);
 966
 967 static int net_dm_hw_monitor_start(struct netlink_ext_ack *extack)
 968 {
 969         const struct net_dm_alert_ops *ops;
 970         int cpu;
 971
 972         if (monitor_hw) {
 973                 NL_SET_ERR_MSG_MOD(extack, "Hardware monitoring already enabled");
 974                 return -EAGAIN;
 975         }
 976
 977         ops = net_dm_alert_ops_arr[net_dm_alert_mode];
 978
 979         if (!try_module_get(THIS_MODULE)) {
 980                 NL_SET_ERR_MSG_MOD(extack, "Failed to take reference on module");
 981                 return -ENODEV;
 982         }
 983
 984         for_each_possible_cpu(cpu) {
 985                 struct per_cpu_dm_data *hw_data = &per_cpu(dm_hw_cpu_data, cpu);
 986                 struct net_dm_hw_entries *hw_entries;
 987
 988                 INIT_WORK(&hw_data->dm_alert_work, ops->hw_work_item_func);
 989                 timer_setup(&hw_data->send_timer, sched_send_work, 0);
 990                 hw_entries = net_dm_hw_reset_per_cpu_data(hw_data);
 991                 kfree(hw_entries);
 992         }
 993
 994         monitor_hw = true;
 995
 996         return 0;
 997 }
 998
 999 static void net_dm_hw_monitor_stop(struct netlink_ext_ack *extack)
1000 {
1001         int cpu;
1002
1003         if (!monitor_hw) {
1004                 NL_SET_ERR_MSG_MOD(extack, "Hardware monitoring already disabled");
1005                 return;
1006         }
1007
1008         monitor_hw = false;
1009
1010         /* After this call returns we are guaranteed that no CPU is processing
1011          * any hardware drops.
1012          */
1013         synchronize_rcu();
1014
1015         for_each_possible_cpu(cpu) {
1016                 struct per_cpu_dm_data *hw_data = &per_cpu(dm_hw_cpu_data, cpu);
1017                 struct sk_buff *skb;
1018
1019                 del_timer_sync(&hw_data->send_timer);
1020                 cancel_work_sync(&hw_data->dm_alert_work);
1021                 while ((skb = __skb_dequeue(&hw_data->drop_queue))) {
1022                         struct net_dm_hw_metadata *hw_metadata;
1023
1024                         hw_metadata = NET_DM_SKB_CB(skb)->hw_metadata;
1025                         net_dm_hw_metadata_free(hw_metadata);
1026                         consume_skb(skb);
1027                 }
1028         }
1029
1030         module_put(THIS_MODULE);
1031 }
1032
1033 static int net_dm_trace_on_set(struct netlink_ext_ack *extack)
1034 {
1035         const struct net_dm_alert_ops *ops;
1036         int cpu, rc;
1037
1038         ops = net_dm_alert_ops_arr[net_dm_alert_mode];
1039
1040         if (!try_module_get(THIS_MODULE)) {
1041                 NL_SET_ERR_MSG_MOD(extack, "Failed to take reference on module");
1042                 return -ENODEV;
1043         }
1044
1045         for_each_possible_cpu(cpu) {
1046                 struct per_cpu_dm_data *data = &per_cpu(dm_cpu_data, cpu);
1047                 struct sk_buff *skb;
1048
1049                 INIT_WORK(&data->dm_alert_work, ops->work_item_func);
1050                 timer_setup(&data->send_timer, sched_send_work, 0);
1051                 /* Allocate a new per-CPU skb for the summary alert message and
1052                  * free the old one which might contain stale data from
1053                  * previous tracing.
1054                  */
1055                 skb = reset_per_cpu_data(data);
1056                 consume_skb(skb);
1057         }
1058
1059         rc = register_trace_kfree_skb(ops->kfree_skb_probe, NULL);
1060         if (rc) {
1061                 NL_SET_ERR_MSG_MOD(extack, "Failed to connect probe to kfree_skb() tracepoint");
1062                 goto err_module_put;
1063         }
1064
1065         rc = register_trace_napi_poll(ops->napi_poll_probe, NULL);
1066         if (rc) {
1067                 NL_SET_ERR_MSG_MOD(extack, "Failed to connect probe to napi_poll() tracepoint");
1068                 goto err_unregister_trace;
1069         }
1070
1071         return 0;
1072
1073 err_unregister_trace:
1074         unregister_trace_kfree_skb(ops->kfree_skb_probe, NULL);
1075 err_module_put:
1076         module_put(THIS_MODULE);
1077         return rc;
1078 }
1079
1080 static void net_dm_trace_off_set(void)
1081 {
1082         struct dm_hw_stat_delta *new_stat, *temp;
1083         const struct net_dm_alert_ops *ops;
1084         int cpu;
1085
1086         ops = net_dm_alert_ops_arr[net_dm_alert_mode];
1087
1088         unregister_trace_napi_poll(ops->napi_poll_probe, NULL);
1089         unregister_trace_kfree_skb(ops->kfree_skb_probe, NULL);
1090
1091         tracepoint_synchronize_unregister();
1092
1093         /* Make sure we do not send notifications to user space after request
1094          * to stop tracing returns.
1095          */
1096         for_each_possible_cpu(cpu) {
1097                 struct per_cpu_dm_data *data = &per_cpu(dm_cpu_data, cpu);
1098                 struct sk_buff *skb;
1099
1100                 del_timer_sync(&data->send_timer);
1101                 cancel_work_sync(&data->dm_alert_work);
1102                 while ((skb = __skb_dequeue(&data->drop_queue)))
1103                         consume_skb(skb);
1104         }
1105
1106         list_for_each_entry_safe(new_stat, temp, &hw_stats_list, list) {
1107                 if (new_stat->dev == NULL) {
1108                         list_del_rcu(&new_stat->list);
1109                         kfree_rcu(new_stat, rcu);
1110                 }
1111         }
1112
1113         module_put(THIS_MODULE);
1114 }
1115
1116 static int set_all_monitor_traces(int state, struct netlink_ext_ack *extack)
1117 {
1118         int rc = 0;
1119
1120         if (state == trace_state) {
1121                 NL_SET_ERR_MSG_MOD(extack, "Trace state already set to requested state");
1122                 return -EAGAIN;
1123         }
1124
1125         switch (state) {
1126         case TRACE_ON:
1127                 rc = net_dm_trace_on_set(extack);
1128                 break;
1129         case TRACE_OFF:
1130                 net_dm_trace_off_set();
1131                 break;
1132         default:
1133                 rc = 1;
1134                 break;
1135         }
1136
1137         if (!rc)
1138                 trace_state = state;
1139         else
1140                 rc = -EINPROGRESS;
1141
1142         return rc;
1143 }
1144
1145 static bool net_dm_is_monitoring(void)
1146 {
1147         return trace_state == TRACE_ON || monitor_hw;
1148 }
1149
1150 static int net_dm_alert_mode_get_from_info(struct genl_info *info,
1151                                            enum net_dm_alert_mode *p_alert_mode)
1152 {
1153         u8 val;
1154
1155         val = nla_get_u8(info->attrs[NET_DM_ATTR_ALERT_MODE]);
1156
1157         switch (val) {
1158         case NET_DM_ALERT_MODE_SUMMARY: /* fall-through */
1159         case NET_DM_ALERT_MODE_PACKET:
1160                 *p_alert_mode = val;
1161                 break;
1162         default:
1163                 return -EINVAL;
1164         }
1165
1166         return 0;
1167 }
1168
1169 static int net_dm_alert_mode_set(struct genl_info *info)
1170 {
1171         struct netlink_ext_ack *extack = info->extack;
1172         enum net_dm_alert_mode alert_mode;
1173         int rc;
1174
1175         if (!info->attrs[NET_DM_ATTR_ALERT_MODE])
1176                 return 0;
1177
1178         rc = net_dm_alert_mode_get_from_info(info, &alert_mode);
1179         if (rc) {
1180                 NL_SET_ERR_MSG_MOD(extack, "Invalid alert mode");
1181                 return -EINVAL;
1182         }
1183
1184         net_dm_alert_mode = alert_mode;
1185
1186         return 0;
1187 }
1188
1189 static void net_dm_trunc_len_set(struct genl_info *info)
1190 {
1191         if (!info->attrs[NET_DM_ATTR_TRUNC_LEN])
1192                 return;
1193
1194         net_dm_trunc_len = nla_get_u32(info->attrs[NET_DM_ATTR_TRUNC_LEN]);
1195 }
1196
1197 static void net_dm_queue_len_set(struct genl_info *info)
1198 {
1199         if (!info->attrs[NET_DM_ATTR_QUEUE_LEN])
1200                 return;
1201
1202         net_dm_queue_len = nla_get_u32(info->attrs[NET_DM_ATTR_QUEUE_LEN]);
1203 }
1204
1205 static int net_dm_cmd_config(struct sk_buff *skb,
1206                         struct genl_info *info)
1207 {
1208         struct netlink_ext_ack *extack = info->extack;
1209         int rc;
1210
1211         if (net_dm_is_monitoring()) {
1212                 NL_SET_ERR_MSG_MOD(extack, "Cannot configure drop monitor during monitoring");
1213                 return -EBUSY;
1214         }
1215
1216         rc = net_dm_alert_mode_set(info);
1217         if (rc)
1218                 return rc;
1219
1220         net_dm_trunc_len_set(info);
1221
1222         net_dm_queue_len_set(info);
1223
1224         return 0;
1225 }
1226
1227 static int net_dm_monitor_start(bool set_sw, bool set_hw,
1228                                 struct netlink_ext_ack *extack)
1229 {
1230         bool sw_set = false;
1231         int rc;
1232
1233         if (set_sw) {
1234                 rc = set_all_monitor_traces(TRACE_ON, extack);
1235                 if (rc)
1236                         return rc;
1237                 sw_set = true;
1238         }
1239
1240         if (set_hw) {
1241                 rc = net_dm_hw_monitor_start(extack);
1242                 if (rc)
1243                         goto err_monitor_hw;
1244         }
1245
1246         return 0;
1247
1248 err_monitor_hw:
1249         if (sw_set)
1250                 set_all_monitor_traces(TRACE_OFF, extack);
1251         return rc;
1252 }
1253
1254 static void net_dm_monitor_stop(bool set_sw, bool set_hw,
1255                                 struct netlink_ext_ack *extack)
1256 {
1257         if (set_hw)
1258                 net_dm_hw_monitor_stop(extack);
1259         if (set_sw)
1260                 set_all_monitor_traces(TRACE_OFF, extack);
1261 }
1262
1263 static int net_dm_cmd_trace(struct sk_buff *skb,
1264                         struct genl_info *info)
1265 {
1266         bool set_sw = !!info->attrs[NET_DM_ATTR_SW_DROPS];
1267         bool set_hw = !!info->attrs[NET_DM_ATTR_HW_DROPS];
1268         struct netlink_ext_ack *extack = info->extack;
1269
1270         /* To maintain backward compatibility, we start / stop monitoring of
1271          * software drops if no flag is specified.
1272          */
1273         if (!set_sw && !set_hw)
1274                 set_sw = true;
1275
1276         switch (info->genlhdr->cmd) {
1277         case NET_DM_CMD_START:
1278                 return net_dm_monitor_start(set_sw, set_hw, extack);
1279         case NET_DM_CMD_STOP:
1280                 net_dm_monitor_stop(set_sw, set_hw, extack);
1281                 return 0;
1282         }
1283
1284         return -EOPNOTSUPP;
1285 }
1286
1287 static int net_dm_config_fill(struct sk_buff *msg, struct genl_info *info)
1288 {
1289         void *hdr;
1290
1291         hdr = genlmsg_put(msg, info->snd_portid, info->snd_seq,
1292                           &net_drop_monitor_family, 0, NET_DM_CMD_CONFIG_NEW);
1293         if (!hdr)
1294                 return -EMSGSIZE;
1295
1296         if (nla_put_u8(msg, NET_DM_ATTR_ALERT_MODE, net_dm_alert_mode))
1297                 goto nla_put_failure;
1298
1299         if (nla_put_u32(msg, NET_DM_ATTR_TRUNC_LEN, net_dm_trunc_len))
1300                 goto nla_put_failure;
1301
1302         if (nla_put_u32(msg, NET_DM_ATTR_QUEUE_LEN, net_dm_queue_len))
1303                 goto nla_put_failure;
1304
1305         genlmsg_end(msg, hdr);
1306
1307         return 0;
1308
1309 nla_put_failure:
1310         genlmsg_cancel(msg, hdr);
1311         return -EMSGSIZE;
1312 }
1313
1314 static int net_dm_cmd_config_get(struct sk_buff *skb, struct genl_info *info)
1315 {
1316         struct sk_buff *msg;
1317         int rc;
1318
1319         msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
1320         if (!msg)
1321                 return -ENOMEM;
1322
1323         rc = net_dm_config_fill(msg, info);
1324         if (rc)
1325                 goto free_msg;
1326
1327         return genlmsg_reply(msg, info);
1328
1329 free_msg:
1330         nlmsg_free(msg);
1331         return rc;
1332 }
1333
1334 static void net_dm_stats_read(struct net_dm_stats *stats)
1335 {
1336         int cpu;
1337
1338         memset(stats, 0, sizeof(*stats));
1339         for_each_possible_cpu(cpu) {
1340                 struct per_cpu_dm_data *data = &per_cpu(dm_cpu_data, cpu);
1341                 struct net_dm_stats *cpu_stats = &data->stats;
1342                 unsigned int start;
1343                 u64 dropped;
1344
1345                 do {
1346                         start = u64_stats_fetch_begin_irq(&cpu_stats->syncp);
1347                         dropped = cpu_stats->dropped;
1348                 } while (u64_stats_fetch_retry_irq(&cpu_stats->syncp, start));
1349
1350                 stats->dropped += dropped;
1351         }
1352 }
1353
1354 static int net_dm_stats_put(struct sk_buff *msg)
1355 {
1356         struct net_dm_stats stats;
1357         struct nlattr *attr;
1358
1359         net_dm_stats_read(&stats);
1360
1361         attr = nla_nest_start(msg, NET_DM_ATTR_STATS);
1362         if (!attr)
1363                 return -EMSGSIZE;
1364
1365         if (nla_put_u64_64bit(msg, NET_DM_ATTR_STATS_DROPPED,
1366                               stats.dropped, NET_DM_ATTR_PAD))
1367                 goto nla_put_failure;
1368
1369         nla_nest_end(msg, attr);
1370
1371         return 0;
1372
1373 nla_put_failure:
1374         nla_nest_cancel(msg, attr);
1375         return -EMSGSIZE;
1376 }
1377
1378 static void net_dm_hw_stats_read(struct net_dm_stats *stats)
1379 {
1380         int cpu;
1381
1382         memset(stats, 0, sizeof(*stats));
1383         for_each_possible_cpu(cpu) {
1384                 struct per_cpu_dm_data *hw_data = &per_cpu(dm_hw_cpu_data, cpu);
1385                 struct net_dm_stats *cpu_stats = &hw_data->stats;
1386                 unsigned int start;
1387                 u64 dropped;
1388
1389                 do {
1390                         start = u64_stats_fetch_begin_irq(&cpu_stats->syncp);
1391                         dropped = cpu_stats->dropped;
1392                 } while (u64_stats_fetch_retry_irq(&cpu_stats->syncp, start));
1393
1394                 stats->dropped += dropped;
1395         }
1396 }
1397
1398 static int net_dm_hw_stats_put(struct sk_buff *msg)
1399 {
1400         struct net_dm_stats stats;
1401         struct nlattr *attr;
1402
1403         net_dm_hw_stats_read(&stats);
1404
1405         attr = nla_nest_start(msg, NET_DM_ATTR_HW_STATS);
1406         if (!attr)
1407                 return -EMSGSIZE;
1408
1409         if (nla_put_u64_64bit(msg, NET_DM_ATTR_STATS_DROPPED,
1410                               stats.dropped, NET_DM_ATTR_PAD))
1411                 goto nla_put_failure;
1412
1413         nla_nest_end(msg, attr);
1414
1415         return 0;
1416
1417 nla_put_failure:
1418         nla_nest_cancel(msg, attr);
1419         return -EMSGSIZE;
1420 }
1421
1422 static int net_dm_stats_fill(struct sk_buff *msg, struct genl_info *info)
1423 {
1424         void *hdr;
1425         int rc;
1426
1427         hdr = genlmsg_put(msg, info->snd_portid, info->snd_seq,
1428                           &net_drop_monitor_family, 0, NET_DM_CMD_STATS_NEW);
1429         if (!hdr)
1430                 return -EMSGSIZE;
1431
1432         rc = net_dm_stats_put(msg);
1433         if (rc)
1434                 goto nla_put_failure;
1435
1436         rc = net_dm_hw_stats_put(msg);
1437         if (rc)
1438                 goto nla_put_failure;
1439
1440         genlmsg_end(msg, hdr);
1441
1442         return 0;
1443
1444 nla_put_failure:
1445         genlmsg_cancel(msg, hdr);
1446         return -EMSGSIZE;
1447 }
1448
1449 static int net_dm_cmd_stats_get(struct sk_buff *skb, struct genl_info *info)
1450 {
1451         struct sk_buff *msg;
1452         int rc;
1453
1454         msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
1455         if (!msg)
1456                 return -ENOMEM;
1457
1458         rc = net_dm_stats_fill(msg, info);
1459         if (rc)
1460                 goto free_msg;
1461
1462         return genlmsg_reply(msg, info);
1463
1464 free_msg:
1465         nlmsg_free(msg);
1466         return rc;
1467 }
1468
1469 static int dropmon_net_event(struct notifier_block *ev_block,
1470                              unsigned long event, void *ptr)
1471 {
1472         struct net_device *dev = netdev_notifier_info_to_dev(ptr);
1473         struct dm_hw_stat_delta *new_stat = NULL;
1474         struct dm_hw_stat_delta *tmp;
1475
1476         switch (event) {
1477         case NETDEV_REGISTER:
1478                 new_stat = kzalloc(sizeof(struct dm_hw_stat_delta), GFP_KERNEL);
1479
1480                 if (!new_stat)
1481                         goto out;
1482
1483                 new_stat->dev = dev;
1484                 new_stat->last_rx = jiffies;
1485                 mutex_lock(&net_dm_mutex);
1486                 list_add_rcu(&new_stat->list, &hw_stats_list);
1487                 mutex_unlock(&net_dm_mutex);
1488                 break;
1489         case NETDEV_UNREGISTER:
1490                 mutex_lock(&net_dm_mutex);
1491                 list_for_each_entry_safe(new_stat, tmp, &hw_stats_list, list) {
1492                         if (new_stat->dev == dev) {
1493                                 new_stat->dev = NULL;
1494                                 if (trace_state == TRACE_OFF) {
1495                                         list_del_rcu(&new_stat->list);
1496                                         kfree_rcu(new_stat, rcu);
1497                                         break;
1498                                 }
1499                         }
1500                 }
1501                 mutex_unlock(&net_dm_mutex);
1502                 break;
1503         }
1504 out:
1505         return NOTIFY_DONE;
1506 }
1507
1508 static const struct nla_policy net_dm_nl_policy[NET_DM_ATTR_MAX + 1] = {
1509         [NET_DM_ATTR_UNSPEC] = { .strict_start_type = NET_DM_ATTR_UNSPEC + 1 },
1510         [NET_DM_ATTR_ALERT_MODE] = { .type = NLA_U8 },
1511         [NET_DM_ATTR_TRUNC_LEN] = { .type = NLA_U32 },
1512         [NET_DM_ATTR_QUEUE_LEN] = { .type = NLA_U32 },
1513         [NET_DM_ATTR_SW_DROPS]  = {. type = NLA_FLAG },
1514         [NET_DM_ATTR_HW_DROPS]  = {. type = NLA_FLAG },
1515 };
1516
1517 static const struct genl_ops dropmon_ops[] = {
1518         {
1519                 .cmd = NET_DM_CMD_CONFIG,
1520                 .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
1521                 .doit = net_dm_cmd_config,
1522                 .flags = GENL_ADMIN_PERM,
1523         },
1524         {
1525                 .cmd = NET_DM_CMD_START,
1526                 .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
1527                 .doit = net_dm_cmd_trace,
1528         },
1529         {
1530                 .cmd = NET_DM_CMD_STOP,
1531                 .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
1532                 .doit = net_dm_cmd_trace,
1533         },
1534         {
1535                 .cmd = NET_DM_CMD_CONFIG_GET,
1536                 .doit = net_dm_cmd_config_get,
1537         },
1538         {
1539                 .cmd = NET_DM_CMD_STATS_GET,
1540                 .doit = net_dm_cmd_stats_get,
1541         },
1542 };
1543
1544 static int net_dm_nl_pre_doit(const struct genl_ops *ops,
1545                               struct sk_buff *skb, struct genl_info *info)
1546 {
1547         mutex_lock(&net_dm_mutex);
1548
1549         return 0;
1550 }
1551
1552 static void net_dm_nl_post_doit(const struct genl_ops *ops,
1553                                 struct sk_buff *skb, struct genl_info *info)
1554 {
1555         mutex_unlock(&net_dm_mutex);
1556 }
1557
1558 static struct genl_family net_drop_monitor_family __ro_after_init = {
1559         .hdrsize        = 0,
1560         .name           = "NET_DM",
1561         .version        = 2,
1562         .maxattr        = NET_DM_ATTR_MAX,
1563         .policy         = net_dm_nl_policy,
1564         .pre_doit       = net_dm_nl_pre_doit,
1565         .post_doit      = net_dm_nl_post_doit,
1566         .module         = THIS_MODULE,
1567         .ops            = dropmon_ops,
1568         .n_ops          = ARRAY_SIZE(dropmon_ops),
1569         .mcgrps         = dropmon_mcgrps,
1570         .n_mcgrps       = ARRAY_SIZE(dropmon_mcgrps),
1571 };
1572
1573 static struct notifier_block dropmon_net_notifier = {
1574         .notifier_call = dropmon_net_event
1575 };
1576
1577 static void __net_dm_cpu_data_init(struct per_cpu_dm_data *data)
1578 {
1579         spin_lock_init(&data->lock);
1580         skb_queue_head_init(&data->drop_queue);
1581         u64_stats_init(&data->stats.syncp);
1582 }
1583
1584 static void __net_dm_cpu_data_fini(struct per_cpu_dm_data *data)
1585 {
1586         WARN_ON(!skb_queue_empty(&data->drop_queue));
1587 }
1588
1589 static void net_dm_cpu_data_init(int cpu)
1590 {
1591         struct per_cpu_dm_data *data;
1592
1593         data = &per_cpu(dm_cpu_data, cpu);
1594         __net_dm_cpu_data_init(data);
1595 }
1596
1597 static void net_dm_cpu_data_fini(int cpu)
1598 {
1599         struct per_cpu_dm_data *data;
1600
1601         data = &per_cpu(dm_cpu_data, cpu);
1602         /* At this point, we should have exclusive access
1603          * to this struct and can free the skb inside it.
1604          */
1605         consume_skb(data->skb);
1606         __net_dm_cpu_data_fini(data);
1607 }
1608
1609 static void net_dm_hw_cpu_data_init(int cpu)
1610 {
1611         struct per_cpu_dm_data *hw_data;
1612
1613         hw_data = &per_cpu(dm_hw_cpu_data, cpu);
1614         __net_dm_cpu_data_init(hw_data);
1615 }
1616
1617 static void net_dm_hw_cpu_data_fini(int cpu)
1618 {
1619         struct per_cpu_dm_data *hw_data;
1620
1621         hw_data = &per_cpu(dm_hw_cpu_data, cpu);
1622         kfree(hw_data->hw_entries);
1623         __net_dm_cpu_data_fini(hw_data);
1624 }
1625
1626 static int __init init_net_drop_monitor(void)
1627 {
1628         int cpu, rc;
1629
1630         pr_info("Initializing network drop monitor service\n");
1631
1632         if (sizeof(void *) > 8) {
1633                 pr_err("Unable to store program counters on this arch, Drop monitor failed\n");
1634                 return -ENOSPC;
1635         }
1636
1637         rc = genl_register_family(&net_drop_monitor_family);
1638         if (rc) {
1639                 pr_err("Could not create drop monitor netlink family\n");
1640                 return rc;
1641         }
1642         WARN_ON(net_drop_monitor_family.mcgrp_offset != NET_DM_GRP_ALERT);
1643
1644         rc = register_netdevice_notifier(&dropmon_net_notifier);
1645         if (rc < 0) {
1646                 pr_crit("Failed to register netdevice notifier\n");
1647                 goto out_unreg;
1648         }
1649
1650         rc = 0;
1651
1652         for_each_possible_cpu(cpu) {
1653                 net_dm_cpu_data_init(cpu);
1654                 net_dm_hw_cpu_data_init(cpu);
1655         }
1656
1657         goto out;
1658
1659 out_unreg:
1660         genl_unregister_family(&net_drop_monitor_family);
1661 out:
1662         return rc;
1663 }
1664
1665 static void exit_net_drop_monitor(void)
1666 {
1667         int cpu;
1668
1669         BUG_ON(unregister_netdevice_notifier(&dropmon_net_notifier));
1670
1671         /*
1672          * Because of the module_get/put we do in the trace state change path
1673          * we are guarnateed not to have any current users when we get here
1674          */
1675
1676         for_each_possible_cpu(cpu) {
1677                 net_dm_hw_cpu_data_fini(cpu);
1678                 net_dm_cpu_data_fini(cpu);
1679         }
1680
1681         BUG_ON(genl_unregister_family(&net_drop_monitor_family));
1682 }
1683
1684 module_init(init_net_drop_monitor);
1685 module_exit(exit_net_drop_monitor);
1686
1687 MODULE_LICENSE("GPL v2");
1688 MODULE_AUTHOR("Neil Horman <nhorman@tuxdriver.com>");
1689 MODULE_ALIAS_GENL_FAMILY("NET_DM");