summaryrefslogtreecommitdiff
path: root/net/core/drop_monitor.c
blob: 9fd0dc3cca99f5bad5af9fdbc189c528573fcc90 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
/*
 * Monitoring code for network dropped packet alerts
 *
 * Copyright (C) 2009 Neil Horman <nhorman@tuxdriver.com>
 */

#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/string.h>
#include <linux/if_arp.h>
#include <linux/inetdevice.h>
#include <linux/inet.h>
#include <linux/interrupt.h>
#include <linux/netpoll.h>
#include <linux/sched.h>
#include <linux/delay.h>
#include <linux/types.h>
#include <linux/workqueue.h>
#include <linux/netlink.h>
#include <linux/net_dropmon.h>
#include <linux/percpu.h>
#include <linux/timer.h>
#include <linux/bitops.h>
#include <net/genetlink.h>

#include <trace/skb.h>

#include <asm/unaligned.h>

#define TRACE_ON 1
#define TRACE_OFF 0

static void send_dm_alert(struct work_struct *unused);


/*
 * Globals, our netlink socket pointer
 * and the work handle that will send up
 * netlink alerts
 */
struct sock *dm_sock;

struct per_cpu_dm_data {
	struct work_struct dm_alert_work;
	struct sk_buff *skb;
	atomic_t dm_hit_count;
	struct timer_list send_timer;
};

static struct genl_family net_drop_monitor_family = {
	.id             = GENL_ID_GENERATE,
	.hdrsize        = 0,
	.name           = "NET_DM",
	.version        = 1,
	.maxattr        = NET_DM_CMD_MAX,
};

static DEFINE_PER_CPU(struct per_cpu_dm_data, dm_cpu_data);

static int dm_hit_limit = 64;
static int dm_delay = 1;


static void reset_per_cpu_data(struct per_cpu_dm_data *data)
{
	size_t al;
	struct net_dm_alert_msg *msg;

	al = sizeof(struct net_dm_alert_msg);
	al += dm_hit_limit * sizeof(struct net_dm_drop_point);
	data->skb = genlmsg_new(al, GFP_KERNEL);
	genlmsg_put(data->skb, 0, 0, &net_drop_monitor_family,
			0, NET_DM_CMD_ALERT);
	msg = __nla_reserve_nohdr(data->skb, sizeof(struct net_dm_alert_msg));
	memset(msg, 0, al);
	atomic_set(&data->dm_hit_count, dm_hit_limit);
}

static void send_dm_alert(struct work_struct *unused)
{
	struct sk_buff *skb;
	struct per_cpu_dm_data *data = &__get_cpu_var(dm_cpu_data);

	/*
	 * Grab the skb we're about to send
	 */
	skb = data->skb;

	/*
	 * Replace it with a new one
	 */
	reset_per_cpu_data(data);

	/*
	 * Ship it!
	 */
	genlmsg_multicast(skb, 0, NET_DM_GRP_ALERT, GFP_KERNEL);

}

/*
 * This is the timer function to delay the sending of an alert
 * in the event that more drops will arrive during the
 * hysteresis period.  Note that it operates under the timer interrupt
 * so we don't need to disable preemption here
 */
static void sched_send_work(unsigned long unused)
{
	struct per_cpu_dm_data *data =  &__get_cpu_var(dm_cpu_data);

	schedule_work(&data->dm_alert_work);
}

static void trace_kfree_skb_hit(struct sk_buff *skb, void *location)
{
	struct net_dm_alert_msg *msg;
	struct nlmsghdr *nlh;
	int i;
	struct per_cpu_dm_data *data = &__get_cpu_var(dm_cpu_data);


	if (!atomic_add_unless(&data->dm_hit_count, -1, 0)) {
		/*
		 * we're already at zero, discard this hit
		 */
		goto out;
	}

	nlh = (struct nlmsghdr *)data->skb->data;
	msg = genlmsg_data(nlmsg_data(nlh));
	for (i = 0; i < msg->entries; i++) {
		if (!memcmp(&location, msg->points[i].pc, sizeof(void *))) {
			msg->points[i].count++;
			goto out;
		}
	}

	/*
	 * We need to create a new entry
	 */
	__nla_reserve_nohdr(data->skb, sizeof(struct net_dm_drop_point));
	memcpy(msg->points[msg->entries].pc, &location, sizeof(void *));
	msg->points[msg->entries].count = 1;
	msg->entries++;

	if (!timer_pending(&data->send_timer)) {
		data->send_timer.expires = jiffies + dm_delay * HZ;
		add_timer_on(&data->send_timer, smp_processor_id());
	}

out:
	return;
}

static int set_all_monitor_traces(int state)
{
	int rc = 0;

	switch (state) {
	case TRACE_ON:
		rc |= register_trace_kfree_skb(trace_kfree_skb_hit);
		break;
	case TRACE_OFF:
		rc |= unregister_trace_kfree_skb(trace_kfree_skb_hit);

		tracepoint_synchronize_unregister();
		break;
	default:
		rc = 1;
		break;
	}

	if (rc)
		return -EINPROGRESS;
	return rc;
}


static int net_dm_cmd_config(struct sk_buff *skb,
			struct genl_info *info)
{
	return -ENOTSUPP;
}

static int net_dm_cmd_trace(struct sk_buff *skb,
			struct genl_info *info)
{
	switch (info->genlhdr->cmd) {
	case NET_DM_CMD_START:
		return set_all_monitor_traces(TRACE_ON);
		break;
	case NET_DM_CMD_STOP:
		return set_all_monitor_traces(TRACE_OFF);
		break;
	}

	return -ENOTSUPP;
}


static struct genl_ops dropmon_ops[] = {
	{
		.cmd = NET_DM_CMD_CONFIG,
		.doit = net_dm_cmd_config,
	},
	{
		.cmd = NET_DM_CMD_START,
		.doit = net_dm_cmd_trace,
	},
	{
		.cmd = NET_DM_CMD_STOP,
		.doit = net_dm_cmd_trace,
	},
};

static int __init init_net_drop_monitor(void)
{
	int cpu;
	int rc, i, ret;
	struct per_cpu_dm_data *data;
	printk(KERN_INFO "Initalizing network drop monitor service\n");

	if (sizeof(void *) > 8) {
		printk(KERN_ERR "Unable to store program counters on this arch, Drop monitor failed\n");
		return -ENOSPC;
	}

	if (genl_register_family(&net_drop_monitor_family) < 0) {
		printk(KERN_ERR "Could not create drop monitor netlink family\n");
		return -EFAULT;
	}

	rc = -EFAULT;

	for (i = 0; i < ARRAY_SIZE(dropmon_ops); i++) {
		ret = genl_register_ops(&net_drop_monitor_family,
					&dropmon_ops[i]);
		if (ret) {
			printk(KERN_CRIT "failed to register operation %d\n",
				dropmon_ops[i].cmd);
			goto out_unreg;
		}
	}

	rc = 0;

	for_each_present_cpu(cpu) {
		data = &per_cpu(dm_cpu_data, cpu);
		reset_per_cpu_data(data);
		INIT_WORK(&data->dm_alert_work, send_dm_alert);
		init_timer(&data->send_timer);
		data->send_timer.data = cpu;
		data->send_timer.function = sched_send_work;
	}
	goto out;

out_unreg:
	genl_unregister_family(&net_drop_monitor_family);
out:
	return rc;
}

late_initcall(init_net_drop_monitor);