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/genetlink.h> 30 #include <net/netevent.h> 31 32 #include <trace/events/skb.h> 33 #include <trace/events/napi.h> 34 35 #include <asm/unaligned.h> 36 37 #define TRACE_ON 1 38 #define TRACE_OFF 0 39 40 /* 41 * Globals, our netlink socket pointer 42 * and the work handle that will send up 43 * netlink alerts 44 */ 45 static int trace_state = TRACE_OFF; 46 static DEFINE_MUTEX(trace_state_mutex); 47 48 struct per_cpu_dm_data { 49 spinlock_t lock; 50 struct sk_buff *skb; 51 struct work_struct dm_alert_work; 52 struct timer_list send_timer; 53 }; 54 55 struct dm_hw_stat_delta { 56 struct net_device *dev; 57 unsigned long last_rx; 58 struct list_head list; 59 struct rcu_head rcu; 60 unsigned long last_drop_val; 61 }; 62 63 static struct genl_family net_drop_monitor_family; 64 65 static DEFINE_PER_CPU(struct per_cpu_dm_data, dm_cpu_data); 66 67 static int dm_hit_limit = 64; 68 static int dm_delay = 1; 69 static unsigned long dm_hw_check_delta = 2*HZ; 70 static LIST_HEAD(hw_stats_list); 71 72 static struct sk_buff *reset_per_cpu_data(struct per_cpu_dm_data *data) 73 { 74 size_t al; 75 struct net_dm_alert_msg *msg; 76 struct nlattr *nla; 77 struct sk_buff *skb; 78 unsigned long flags; 79 void *msg_header; 80 81 al = sizeof(struct net_dm_alert_msg); 82 al += dm_hit_limit * sizeof(struct net_dm_drop_point); 83 al += sizeof(struct nlattr); 84 85 skb = genlmsg_new(al, GFP_KERNEL); 86 87 if (!skb) 88 goto err; 89 90 msg_header = genlmsg_put(skb, 0, 0, &net_drop_monitor_family, 91 0, NET_DM_CMD_ALERT); 92 if (!msg_header) { 93 nlmsg_free(skb); 94 skb = NULL; 95 goto err; 96 } 97 nla = nla_reserve(skb, NLA_UNSPEC, 98 sizeof(struct net_dm_alert_msg)); 99 if (!nla) { 100 nlmsg_free(skb); 101 skb = NULL; 102 goto err; 103 } 104 msg = nla_data(nla); 105 memset(msg, 0, al); 106 goto out; 107 108 err: 109 mod_timer(&data->send_timer, jiffies + HZ / 10); 110 out: 111 spin_lock_irqsave(&data->lock, flags); 112 swap(data->skb, skb); 113 spin_unlock_irqrestore(&data->lock, flags); 114 115 if (skb) { 116 struct nlmsghdr *nlh = (struct nlmsghdr *)skb->data; 117 struct genlmsghdr *gnlh = (struct genlmsghdr *)nlmsg_data(nlh); 118 119 genlmsg_end(skb, genlmsg_data(gnlh)); 120 } 121 122 return skb; 123 } 124 125 static const struct genl_multicast_group dropmon_mcgrps[] = { 126 { .name = "events", }, 127 }; 128 129 static void send_dm_alert(struct work_struct *work) 130 { 131 struct sk_buff *skb; 132 struct per_cpu_dm_data *data; 133 134 data = container_of(work, struct per_cpu_dm_data, dm_alert_work); 135 136 skb = reset_per_cpu_data(data); 137 138 if (skb) 139 genlmsg_multicast(&net_drop_monitor_family, skb, 0, 140 0, GFP_KERNEL); 141 } 142 143 /* 144 * This is the timer function to delay the sending of an alert 145 * in the event that more drops will arrive during the 146 * hysteresis period. 147 */ 148 static void sched_send_work(struct timer_list *t) 149 { 150 struct per_cpu_dm_data *data = from_timer(data, t, send_timer); 151 152 schedule_work(&data->dm_alert_work); 153 } 154 155 static void trace_drop_common(struct sk_buff *skb, void *location) 156 { 157 struct net_dm_alert_msg *msg; 158 struct nlmsghdr *nlh; 159 struct nlattr *nla; 160 int i; 161 struct sk_buff *dskb; 162 struct per_cpu_dm_data *data; 163 unsigned long flags; 164 165 local_irq_save(flags); 166 data = this_cpu_ptr(&dm_cpu_data); 167 spin_lock(&data->lock); 168 dskb = data->skb; 169 170 if (!dskb) 171 goto out; 172 173 nlh = (struct nlmsghdr *)dskb->data; 174 nla = genlmsg_data(nlmsg_data(nlh)); 175 msg = nla_data(nla); 176 for (i = 0; i < msg->entries; i++) { 177 if (!memcmp(&location, msg->points[i].pc, sizeof(void *))) { 178 msg->points[i].count++; 179 goto out; 180 } 181 } 182 if (msg->entries == dm_hit_limit) 183 goto out; 184 /* 185 * We need to create a new entry 186 */ 187 __nla_reserve_nohdr(dskb, sizeof(struct net_dm_drop_point)); 188 nla->nla_len += NLA_ALIGN(sizeof(struct net_dm_drop_point)); 189 memcpy(msg->points[msg->entries].pc, &location, sizeof(void *)); 190 msg->points[msg->entries].count = 1; 191 msg->entries++; 192 193 if (!timer_pending(&data->send_timer)) { 194 data->send_timer.expires = jiffies + dm_delay * HZ; 195 add_timer(&data->send_timer); 196 } 197 198 out: 199 spin_unlock_irqrestore(&data->lock, flags); 200 } 201 202 static void trace_kfree_skb_hit(void *ignore, struct sk_buff *skb, void *location) 203 { 204 trace_drop_common(skb, location); 205 } 206 207 static void trace_napi_poll_hit(void *ignore, struct napi_struct *napi, 208 int work, int budget) 209 { 210 struct dm_hw_stat_delta *new_stat; 211 212 /* 213 * Don't check napi structures with no associated device 214 */ 215 if (!napi->dev) 216 return; 217 218 rcu_read_lock(); 219 list_for_each_entry_rcu(new_stat, &hw_stats_list, list) { 220 /* 221 * only add a note to our monitor buffer if: 222 * 1) this is the dev we received on 223 * 2) its after the last_rx delta 224 * 3) our rx_dropped count has gone up 225 */ 226 if ((new_stat->dev == napi->dev) && 227 (time_after(jiffies, new_stat->last_rx + dm_hw_check_delta)) && 228 (napi->dev->stats.rx_dropped != new_stat->last_drop_val)) { 229 trace_drop_common(NULL, NULL); 230 new_stat->last_drop_val = napi->dev->stats.rx_dropped; 231 new_stat->last_rx = jiffies; 232 break; 233 } 234 } 235 rcu_read_unlock(); 236 } 237 238 static int set_all_monitor_traces(int state) 239 { 240 int rc = 0; 241 struct dm_hw_stat_delta *new_stat = NULL; 242 struct dm_hw_stat_delta *temp; 243 244 mutex_lock(&trace_state_mutex); 245 246 if (state == trace_state) { 247 rc = -EAGAIN; 248 goto out_unlock; 249 } 250 251 switch (state) { 252 case TRACE_ON: 253 if (!try_module_get(THIS_MODULE)) { 254 rc = -ENODEV; 255 break; 256 } 257 258 rc |= register_trace_kfree_skb(trace_kfree_skb_hit, NULL); 259 rc |= register_trace_napi_poll(trace_napi_poll_hit, NULL); 260 break; 261 262 case TRACE_OFF: 263 rc |= unregister_trace_kfree_skb(trace_kfree_skb_hit, NULL); 264 rc |= unregister_trace_napi_poll(trace_napi_poll_hit, NULL); 265 266 tracepoint_synchronize_unregister(); 267 268 /* 269 * Clean the device list 270 */ 271 list_for_each_entry_safe(new_stat, temp, &hw_stats_list, list) { 272 if (new_stat->dev == NULL) { 273 list_del_rcu(&new_stat->list); 274 kfree_rcu(new_stat, rcu); 275 } 276 } 277 278 module_put(THIS_MODULE); 279 280 break; 281 default: 282 rc = 1; 283 break; 284 } 285 286 if (!rc) 287 trace_state = state; 288 else 289 rc = -EINPROGRESS; 290 291 out_unlock: 292 mutex_unlock(&trace_state_mutex); 293 294 return rc; 295 } 296 297 298 static int net_dm_cmd_config(struct sk_buff *skb, 299 struct genl_info *info) 300 { 301 return -ENOTSUPP; 302 } 303 304 static int net_dm_cmd_trace(struct sk_buff *skb, 305 struct genl_info *info) 306 { 307 switch (info->genlhdr->cmd) { 308 case NET_DM_CMD_START: 309 return set_all_monitor_traces(TRACE_ON); 310 case NET_DM_CMD_STOP: 311 return set_all_monitor_traces(TRACE_OFF); 312 } 313 314 return -ENOTSUPP; 315 } 316 317 static int dropmon_net_event(struct notifier_block *ev_block, 318 unsigned long event, void *ptr) 319 { 320 struct net_device *dev = netdev_notifier_info_to_dev(ptr); 321 struct dm_hw_stat_delta *new_stat = NULL; 322 struct dm_hw_stat_delta *tmp; 323 324 switch (event) { 325 case NETDEV_REGISTER: 326 new_stat = kzalloc(sizeof(struct dm_hw_stat_delta), GFP_KERNEL); 327 328 if (!new_stat) 329 goto out; 330 331 new_stat->dev = dev; 332 new_stat->last_rx = jiffies; 333 mutex_lock(&trace_state_mutex); 334 list_add_rcu(&new_stat->list, &hw_stats_list); 335 mutex_unlock(&trace_state_mutex); 336 break; 337 case NETDEV_UNREGISTER: 338 mutex_lock(&trace_state_mutex); 339 list_for_each_entry_safe(new_stat, tmp, &hw_stats_list, list) { 340 if (new_stat->dev == dev) { 341 new_stat->dev = NULL; 342 if (trace_state == TRACE_OFF) { 343 list_del_rcu(&new_stat->list); 344 kfree_rcu(new_stat, rcu); 345 break; 346 } 347 } 348 } 349 mutex_unlock(&trace_state_mutex); 350 break; 351 } 352 out: 353 return NOTIFY_DONE; 354 } 355 356 static const struct genl_ops dropmon_ops[] = { 357 { 358 .cmd = NET_DM_CMD_CONFIG, 359 .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP, 360 .doit = net_dm_cmd_config, 361 }, 362 { 363 .cmd = NET_DM_CMD_START, 364 .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP, 365 .doit = net_dm_cmd_trace, 366 }, 367 { 368 .cmd = NET_DM_CMD_STOP, 369 .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP, 370 .doit = net_dm_cmd_trace, 371 }, 372 }; 373 374 static struct genl_family net_drop_monitor_family __ro_after_init = { 375 .hdrsize = 0, 376 .name = "NET_DM", 377 .version = 2, 378 .module = THIS_MODULE, 379 .ops = dropmon_ops, 380 .n_ops = ARRAY_SIZE(dropmon_ops), 381 .mcgrps = dropmon_mcgrps, 382 .n_mcgrps = ARRAY_SIZE(dropmon_mcgrps), 383 }; 384 385 static struct notifier_block dropmon_net_notifier = { 386 .notifier_call = dropmon_net_event 387 }; 388 389 static int __init init_net_drop_monitor(void) 390 { 391 struct per_cpu_dm_data *data; 392 int cpu, rc; 393 394 pr_info("Initializing network drop monitor service\n"); 395 396 if (sizeof(void *) > 8) { 397 pr_err("Unable to store program counters on this arch, Drop monitor failed\n"); 398 return -ENOSPC; 399 } 400 401 rc = genl_register_family(&net_drop_monitor_family); 402 if (rc) { 403 pr_err("Could not create drop monitor netlink family\n"); 404 return rc; 405 } 406 WARN_ON(net_drop_monitor_family.mcgrp_offset != NET_DM_GRP_ALERT); 407 408 rc = register_netdevice_notifier(&dropmon_net_notifier); 409 if (rc < 0) { 410 pr_crit("Failed to register netdevice notifier\n"); 411 goto out_unreg; 412 } 413 414 rc = 0; 415 416 for_each_possible_cpu(cpu) { 417 data = &per_cpu(dm_cpu_data, cpu); 418 INIT_WORK(&data->dm_alert_work, send_dm_alert); 419 timer_setup(&data->send_timer, sched_send_work, 0); 420 spin_lock_init(&data->lock); 421 reset_per_cpu_data(data); 422 } 423 424 425 goto out; 426 427 out_unreg: 428 genl_unregister_family(&net_drop_monitor_family); 429 out: 430 return rc; 431 } 432 433 static void exit_net_drop_monitor(void) 434 { 435 struct per_cpu_dm_data *data; 436 int cpu; 437 438 BUG_ON(unregister_netdevice_notifier(&dropmon_net_notifier)); 439 440 /* 441 * Because of the module_get/put we do in the trace state change path 442 * we are guarnateed not to have any current users when we get here 443 * all we need to do is make sure that we don't have any running timers 444 * or pending schedule calls 445 */ 446 447 for_each_possible_cpu(cpu) { 448 data = &per_cpu(dm_cpu_data, cpu); 449 del_timer_sync(&data->send_timer); 450 cancel_work_sync(&data->dm_alert_work); 451 /* 452 * At this point, we should have exclusive access 453 * to this struct and can free the skb inside it 454 */ 455 kfree_skb(data->skb); 456 } 457 458 BUG_ON(genl_unregister_family(&net_drop_monitor_family)); 459 } 460 461 module_init(init_net_drop_monitor); 462 module_exit(exit_net_drop_monitor); 463 464 MODULE_LICENSE("GPL v2"); 465 MODULE_AUTHOR("Neil Horman <nhorman@tuxdriver.com>"); 466 MODULE_ALIAS_GENL_FAMILY("NET_DM"); 467