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9a8afc8d NH |
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 = 1, | |
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 | ||
69 | al = sizeof(struct net_dm_alert_msg); | |
70 | al += dm_hit_limit * sizeof(struct net_dm_drop_point); | |
71 | data->skb = genlmsg_new(al, GFP_KERNEL); | |
72 | genlmsg_put(data->skb, 0, 0, &net_drop_monitor_family, | |
73 | 0, NET_DM_CMD_ALERT); | |
74 | msg = __nla_reserve_nohdr(data->skb, sizeof(struct net_dm_alert_msg)); | |
75 | memset(msg, 0, al); | |
76 | atomic_set(&data->dm_hit_count, dm_hit_limit); | |
77 | } | |
78 | ||
79 | static void send_dm_alert(struct work_struct *unused) | |
80 | { | |
81 | struct sk_buff *skb; | |
82 | struct per_cpu_dm_data *data = &__get_cpu_var(dm_cpu_data); | |
83 | ||
84 | /* | |
85 | * Grab the skb we're about to send | |
86 | */ | |
87 | skb = data->skb; | |
88 | ||
89 | /* | |
90 | * Replace it with a new one | |
91 | */ | |
92 | reset_per_cpu_data(data); | |
93 | ||
94 | /* | |
95 | * Ship it! | |
96 | */ | |
97 | genlmsg_multicast(skb, 0, NET_DM_GRP_ALERT, GFP_KERNEL); | |
98 | ||
99 | } | |
100 | ||
101 | /* | |
102 | * This is the timer function to delay the sending of an alert | |
103 | * in the event that more drops will arrive during the | |
104 | * hysteresis period. Note that it operates under the timer interrupt | |
105 | * so we don't need to disable preemption here | |
106 | */ | |
107 | static void sched_send_work(unsigned long unused) | |
108 | { | |
109 | struct per_cpu_dm_data *data = &__get_cpu_var(dm_cpu_data); | |
110 | ||
111 | schedule_work(&data->dm_alert_work); | |
112 | } | |
113 | ||
114 | static void trace_kfree_skb_hit(struct sk_buff *skb, void *location) | |
115 | { | |
116 | struct net_dm_alert_msg *msg; | |
117 | struct nlmsghdr *nlh; | |
118 | int i; | |
119 | struct per_cpu_dm_data *data = &__get_cpu_var(dm_cpu_data); | |
120 | ||
121 | ||
122 | if (!atomic_add_unless(&data->dm_hit_count, -1, 0)) { | |
123 | /* | |
124 | * we're already at zero, discard this hit | |
125 | */ | |
126 | goto out; | |
127 | } | |
128 | ||
129 | nlh = (struct nlmsghdr *)data->skb->data; | |
130 | msg = genlmsg_data(nlmsg_data(nlh)); | |
131 | for (i = 0; i < msg->entries; i++) { | |
132 | if (!memcmp(&location, msg->points[i].pc, sizeof(void *))) { | |
133 | msg->points[i].count++; | |
134 | goto out; | |
135 | } | |
136 | } | |
137 | ||
138 | /* | |
139 | * We need to create a new entry | |
140 | */ | |
141 | __nla_reserve_nohdr(data->skb, sizeof(struct net_dm_drop_point)); | |
142 | memcpy(msg->points[msg->entries].pc, &location, sizeof(void *)); | |
143 | msg->points[msg->entries].count = 1; | |
144 | msg->entries++; | |
145 | ||
146 | if (!timer_pending(&data->send_timer)) { | |
147 | data->send_timer.expires = jiffies + dm_delay * HZ; | |
148 | add_timer_on(&data->send_timer, smp_processor_id()); | |
149 | } | |
150 | ||
151 | out: | |
152 | return; | |
153 | } | |
154 | ||
155 | static int set_all_monitor_traces(int state) | |
156 | { | |
157 | int rc = 0; | |
158 | ||
159 | switch (state) { | |
160 | case TRACE_ON: | |
161 | rc |= register_trace_kfree_skb(trace_kfree_skb_hit); | |
162 | break; | |
163 | case TRACE_OFF: | |
164 | rc |= unregister_trace_kfree_skb(trace_kfree_skb_hit); | |
165 | ||
166 | tracepoint_synchronize_unregister(); | |
167 | break; | |
168 | default: | |
169 | rc = 1; | |
170 | break; | |
171 | } | |
172 | ||
173 | if (rc) | |
174 | return -EINPROGRESS; | |
175 | return rc; | |
176 | } | |
177 | ||
178 | ||
179 | static int net_dm_cmd_config(struct sk_buff *skb, | |
180 | struct genl_info *info) | |
181 | { | |
182 | return -ENOTSUPP; | |
183 | } | |
184 | ||
185 | static int net_dm_cmd_trace(struct sk_buff *skb, | |
186 | struct genl_info *info) | |
187 | { | |
188 | switch (info->genlhdr->cmd) { | |
189 | case NET_DM_CMD_START: | |
190 | return set_all_monitor_traces(TRACE_ON); | |
191 | break; | |
192 | case NET_DM_CMD_STOP: | |
193 | return set_all_monitor_traces(TRACE_OFF); | |
194 | break; | |
195 | } | |
196 | ||
197 | return -ENOTSUPP; | |
198 | } | |
199 | ||
200 | ||
201 | static struct genl_ops dropmon_ops[] = { | |
202 | { | |
203 | .cmd = NET_DM_CMD_CONFIG, | |
204 | .doit = net_dm_cmd_config, | |
205 | }, | |
206 | { | |
207 | .cmd = NET_DM_CMD_START, | |
208 | .doit = net_dm_cmd_trace, | |
209 | }, | |
210 | { | |
211 | .cmd = NET_DM_CMD_STOP, | |
212 | .doit = net_dm_cmd_trace, | |
213 | }, | |
214 | }; | |
215 | ||
216 | static int __init init_net_drop_monitor(void) | |
217 | { | |
218 | int cpu; | |
219 | int rc, i, ret; | |
220 | struct per_cpu_dm_data *data; | |
221 | printk(KERN_INFO "Initalizing network drop monitor service\n"); | |
222 | ||
223 | if (sizeof(void *) > 8) { | |
224 | printk(KERN_ERR "Unable to store program counters on this arch, Drop monitor failed\n"); | |
225 | return -ENOSPC; | |
226 | } | |
227 | ||
228 | if (genl_register_family(&net_drop_monitor_family) < 0) { | |
229 | printk(KERN_ERR "Could not create drop monitor netlink family\n"); | |
230 | return -EFAULT; | |
231 | } | |
232 | ||
233 | rc = -EFAULT; | |
234 | ||
235 | for (i = 0; i < ARRAY_SIZE(dropmon_ops); i++) { | |
236 | ret = genl_register_ops(&net_drop_monitor_family, | |
237 | &dropmon_ops[i]); | |
238 | if (ret) { | |
239 | printk(KERN_CRIT "failed to register operation %d\n", | |
240 | dropmon_ops[i].cmd); | |
241 | goto out_unreg; | |
242 | } | |
243 | } | |
244 | ||
245 | rc = 0; | |
246 | ||
247 | for_each_present_cpu(cpu) { | |
248 | data = &per_cpu(dm_cpu_data, cpu); | |
249 | reset_per_cpu_data(data); | |
250 | INIT_WORK(&data->dm_alert_work, send_dm_alert); | |
251 | init_timer(&data->send_timer); | |
252 | data->send_timer.data = cpu; | |
253 | data->send_timer.function = sched_send_work; | |
254 | } | |
255 | goto out; | |
256 | ||
257 | out_unreg: | |
258 | genl_unregister_family(&net_drop_monitor_family); | |
259 | out: | |
260 | return rc; | |
261 | } | |
262 | ||
263 | late_initcall(init_net_drop_monitor); |