net/core/drop_monitor.c

   1 /*
   2  * Monitoring code for network dropped packet alerts
   3  *
   4  * Copyright (C) 2009 Neil Horman <nhorman@tuxdriver.com>
   5  */
   6
   7 #include <linux/netdevice.h>
   8 #include <linux/etherdevice.h>
   9 #include <linux/string.h>
  10 #include <linux/if_arp.h>
  11 #include <linux/inetdevice.h>
  12 #include <linux/inet.h>
  13 #include <linux/interrupt.h>
  14 #include <linux/netpoll.h>
  15 #include <linux/sched.h>
  16 #include <linux/delay.h>
  17 #include <linux/types.h>
  18 #include <linux/workqueue.h>
  19 #include <linux/netlink.h>
  20 #include <linux/net_dropmon.h>
  21 #include <linux/percpu.h>
  22 #include <linux/timer.h>
  23 #include <linux/bitops.h>
  24 #include <net/genetlink.h>
  25
  26 #include <trace/skb.h>
  27
  28 #include <asm/unaligned.h>
  29
  30 #define TRACE_ON 1
  31 #define TRACE_OFF 0
  32
  33 static void send_dm_alert(struct work_struct *unused);
  34
  35
  36 /*
  37  * Globals, our netlink socket pointer
  38  * and the work handle that will send up
  39  * netlink alerts
  40  */
  41 struct sock *dm_sock;
  42
  43 struct per_cpu_dm_data {
  44         struct work_struct dm_alert_work;
  45         struct sk_buff *skb;
  46         atomic_t dm_hit_count;
  47         struct timer_list send_timer;
  48 };
  49
  50 static struct genl_family net_drop_monitor_family = {
  51         .id             = GENL_ID_GENERATE,
  52         .hdrsize        = 0,
  53         .name           = "NET_DM",
  54         .version        = 2,
  55         .maxattr        = NET_DM_CMD_MAX,
  56 };
  57
  58 static DEFINE_PER_CPU(struct per_cpu_dm_data, dm_cpu_data);
  59
  60 static int dm_hit_limit = 64;
  61 static int dm_delay = 1;
  62
  63
  64 static void reset_per_cpu_data(struct per_cpu_dm_data *data)
  65 {
  66         size_t al;
  67         struct net_dm_alert_msg *msg;
  68         struct nlattr *nla;
  69
  70         al = sizeof(struct net_dm_alert_msg);
  71         al += dm_hit_limit * sizeof(struct net_dm_drop_point);
  72         al += sizeof(struct nlattr);
  73
  74         data->skb = genlmsg_new(al, GFP_KERNEL);
  75         genlmsg_put(data->skb, 0, 0, &net_drop_monitor_family,
  76                         0, NET_DM_CMD_ALERT);
  77         nla = nla_reserve(data->skb, NLA_UNSPEC, sizeof(struct net_dm_alert_msg));
  78         msg = nla_data(nla);
  79         memset(msg, 0, al);
  80         atomic_set(&data->dm_hit_count, dm_hit_limit);
  81 }
  82
  83 static void send_dm_alert(struct work_struct *unused)
  84 {
  85         struct sk_buff *skb;
  86         struct per_cpu_dm_data *data = &__get_cpu_var(dm_cpu_data);
  87
  88         /*
  89          * Grab the skb we're about to send
  90          */
  91         skb = data->skb;
  92
  93         /*
  94          * Replace it with a new one
  95          */
  96         reset_per_cpu_data(data);
  97
  98         /*
  99          * Ship it!
 100          */
 101         genlmsg_multicast(skb, 0, NET_DM_GRP_ALERT, GFP_KERNEL);
 102
 103 }
 104
 105 /*
 106  * This is the timer function to delay the sending of an alert
 107  * in the event that more drops will arrive during the
 108  * hysteresis period.  Note that it operates under the timer interrupt
 109  * so we don't need to disable preemption here
 110  */
 111 static void sched_send_work(unsigned long unused)
 112 {
 113         struct per_cpu_dm_data *data =  &__get_cpu_var(dm_cpu_data);
 114
 115         schedule_work(&data->dm_alert_work);
 116 }
 117
 118 static void trace_kfree_skb_hit(struct sk_buff *skb, void *location)
 119 {
 120         struct net_dm_alert_msg *msg;
 121         struct nlmsghdr *nlh;
 122         struct nlattr *nla;
 123         int i;
 124         struct per_cpu_dm_data *data = &__get_cpu_var(dm_cpu_data);
 125
 126
 127         if (!atomic_add_unless(&data->dm_hit_count, -1, 0)) {
 128                 /*
 129                  * we're already at zero, discard this hit
 130                  */
 131                 goto out;
 132         }
 133
 134         nlh = (struct nlmsghdr *)data->skb->data;
 135         nla = genlmsg_data(nlmsg_data(nlh));
 136         msg = nla_data(nla);
 137         for (i = 0; i < msg->entries; i++) {
 138                 if (!memcmp(&location, msg->points[i].pc, sizeof(void *))) {
 139                         msg->points[i].count++;
 140                         goto out;
 141                 }
 142         }
 143
 144         /*
 145          * We need to create a new entry
 146          */
 147         __nla_reserve_nohdr(data->skb, sizeof(struct net_dm_drop_point));
 148         nla->nla_len += NLA_ALIGN(sizeof(struct net_dm_drop_point));
 149         memcpy(msg->points[msg->entries].pc, &location, sizeof(void *));
 150         msg->points[msg->entries].count = 1;
 151         msg->entries++;
 152
 153         if (!timer_pending(&data->send_timer)) {
 154                 data->send_timer.expires = jiffies + dm_delay * HZ;
 155                 add_timer_on(&data->send_timer, smp_processor_id());
 156         }
 157
 158 out:
 159         return;
 160 }
 161
 162 static int set_all_monitor_traces(int state)
 163 {
 164         int rc = 0;
 165
 166         switch (state) {
 167         case TRACE_ON:
 168                 rc |= register_trace_kfree_skb(trace_kfree_skb_hit);
 169                 break;
 170         case TRACE_OFF:
 171                 rc |= unregister_trace_kfree_skb(trace_kfree_skb_hit);
 172
 173                 tracepoint_synchronize_unregister();
 174                 break;
 175         default:
 176                 rc = 1;
 177                 break;
 178         }
 179
 180         if (rc)
 181                 return -EINPROGRESS;
 182         return rc;
 183 }
 184
 185
 186 static int net_dm_cmd_config(struct sk_buff *skb,
 187                         struct genl_info *info)
 188 {
 189         return -ENOTSUPP;
 190 }
 191
 192 static int net_dm_cmd_trace(struct sk_buff *skb,
 193                         struct genl_info *info)
 194 {
 195         switch (info->genlhdr->cmd) {
 196         case NET_DM_CMD_START:
 197                 return set_all_monitor_traces(TRACE_ON);
 198                 break;
 199         case NET_DM_CMD_STOP:
 200                 return set_all_monitor_traces(TRACE_OFF);
 201                 break;
 202         }
 203
 204         return -ENOTSUPP;
 205 }
 206
 207
 208 static struct genl_ops dropmon_ops[] = {
 209         {
 210                 .cmd = NET_DM_CMD_CONFIG,
 211                 .doit = net_dm_cmd_config,
 212         },
 213         {
 214                 .cmd = NET_DM_CMD_START,
 215                 .doit = net_dm_cmd_trace,
 216         },
 217         {
 218                 .cmd = NET_DM_CMD_STOP,
 219                 .doit = net_dm_cmd_trace,
 220         },
 221 };
 222
 223 static int __init init_net_drop_monitor(void)
 224 {
 225         int cpu;
 226         int rc, i, ret;
 227         struct per_cpu_dm_data *data;
 228         printk(KERN_INFO "Initalizing network drop monitor service\n");
 229
 230         if (sizeof(void *) > 8) {
 231                 printk(KERN_ERR "Unable to store program counters on this arch, Drop monitor failed\n");
 232                 return -ENOSPC;
 233         }
 234
 235         if (genl_register_family(&net_drop_monitor_family) < 0) {
 236                 printk(KERN_ERR "Could not create drop monitor netlink family\n");
 237                 return -EFAULT;
 238         }
 239
 240         rc = -EFAULT;
 241
 242         for (i = 0; i < ARRAY_SIZE(dropmon_ops); i++) {
 243                 ret = genl_register_ops(&net_drop_monitor_family,
 244                                         &dropmon_ops[i]);
 245                 if (ret) {
 246                         printk(KERN_CRIT "failed to register operation %d\n",
 247                                 dropmon_ops[i].cmd);
 248                         goto out_unreg;
 249                 }
 250         }
 251
 252         rc = 0;
 253
 254         for_each_present_cpu(cpu) {
 255                 data = &per_cpu(dm_cpu_data, cpu);
 256                 reset_per_cpu_data(data);
 257                 INIT_WORK(&data->dm_alert_work, send_dm_alert);
 258                 init_timer(&data->send_timer);
 259                 data->send_timer.data = cpu;
 260                 data->send_timer.function = sched_send_work;
 261         }
 262         goto out;
 263
 264 out_unreg:
 265         genl_unregister_family(&net_drop_monitor_family);
 266 out:
 267         return rc;
 268 }
 269
 270 late_initcall(init_net_drop_monitor);