Commit | Line | Data |
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a42e9d6c SH |
1 | /* |
2 | * tcpprobe - Observe the TCP flow with kprobes. | |
3 | * | |
4 | * The idea for this came from Werner Almesberger's umlsim | |
5 | * Copyright (C) 2004, Stephen Hemminger <shemminger@osdl.org> | |
6 | * | |
7 | * This program is free software; you can redistribute it and/or modify | |
8 | * it under the terms of the GNU General Public License as published by | |
662ad4f8 | 9 | * the Free Software Foundation; either version 2 of the License. |
a42e9d6c SH |
10 | * |
11 | * This program is distributed in the hope that it will be useful, | |
12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
14 | * GNU General Public License for more details. | |
15 | * | |
16 | * You should have received a copy of the GNU General Public License | |
17 | * along with this program; if not, write to the Free Software | |
18 | * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. | |
19 | */ | |
20 | ||
21 | #include <linux/kernel.h> | |
22 | #include <linux/kprobes.h> | |
23 | #include <linux/socket.h> | |
24 | #include <linux/tcp.h> | |
25 | #include <linux/proc_fs.h> | |
26 | #include <linux/module.h> | |
85795d64 SH |
27 | #include <linux/ktime.h> |
28 | #include <linux/time.h> | |
a42e9d6c SH |
29 | |
30 | #include <net/tcp.h> | |
31 | ||
65ebe634 | 32 | MODULE_AUTHOR("Stephen Hemminger <shemminger@linux-foundation.org>"); |
a42e9d6c SH |
33 | MODULE_DESCRIPTION("TCP cwnd snooper"); |
34 | MODULE_LICENSE("GPL"); | |
662ad4f8 | 35 | MODULE_VERSION("1.1"); |
a42e9d6c | 36 | |
85795d64 | 37 | static int port __read_mostly = 0; |
a42e9d6c SH |
38 | MODULE_PARM_DESC(port, "Port to match (0=all)"); |
39 | module_param(port, int, 0); | |
40 | ||
662ad4f8 SH |
41 | static int bufsize __read_mostly = 4096; |
42 | MODULE_PARM_DESC(bufsize, "Log buffer size in packets (4096)"); | |
a42e9d6c SH |
43 | module_param(bufsize, int, 0); |
44 | ||
85795d64 SH |
45 | static int full __read_mostly; |
46 | MODULE_PARM_DESC(full, "Full log (1=every ack packet received, 0=only cwnd changes)"); | |
47 | module_param(full, int, 0); | |
48 | ||
a42e9d6c SH |
49 | static const char procname[] = "tcpprobe"; |
50 | ||
662ad4f8 SH |
51 | struct tcp_log { |
52 | ktime_t tstamp; | |
53 | __be32 saddr, daddr; | |
54 | __be16 sport, dport; | |
55 | u16 length; | |
56 | u32 snd_nxt; | |
57 | u32 snd_una; | |
58 | u32 snd_wnd; | |
59 | u32 snd_cwnd; | |
60 | u32 ssthresh; | |
61 | u32 srtt; | |
62 | }; | |
63 | ||
64 | static struct { | |
85795d64 | 65 | spinlock_t lock; |
a42e9d6c | 66 | wait_queue_head_t wait; |
85795d64 SH |
67 | ktime_t start; |
68 | u32 lastcwnd; | |
a42e9d6c | 69 | |
662ad4f8 SH |
70 | unsigned long head, tail; |
71 | struct tcp_log *log; | |
72 | } tcp_probe; | |
73 | ||
14a49e1f | 74 | |
662ad4f8 | 75 | static inline int tcp_probe_used(void) |
a42e9d6c | 76 | { |
662ad4f8 SH |
77 | return (tcp_probe.head - tcp_probe.tail) % bufsize; |
78 | } | |
79 | ||
80 | static inline int tcp_probe_avail(void) | |
81 | { | |
82 | return bufsize - tcp_probe_used(); | |
14a49e1f | 83 | } |
a42e9d6c | 84 | |
85795d64 SH |
85 | /* |
86 | * Hook inserted to be called before each receive packet. | |
87 | * Note: arguments must match tcp_rcv_established()! | |
88 | */ | |
89 | static int jtcp_rcv_established(struct sock *sk, struct sk_buff *skb, | |
90 | struct tcphdr *th, unsigned len) | |
a42e9d6c SH |
91 | { |
92 | const struct tcp_sock *tp = tcp_sk(sk); | |
93 | const struct inet_sock *inet = inet_sk(sk); | |
94 | ||
85795d64 SH |
95 | /* Only update if port matches */ |
96 | if ((port == 0 || ntohs(inet->dport) == port || ntohs(inet->sport) == port) | |
662ad4f8 SH |
97 | && (full || tp->snd_cwnd != tcp_probe.lastcwnd)) { |
98 | ||
99 | spin_lock(&tcp_probe.lock); | |
100 | /* If log fills, just silently drop */ | |
101 | if (tcp_probe_avail() > 1) { | |
102 | struct tcp_log *p = tcp_probe.log + tcp_probe.head; | |
103 | ||
104 | p->tstamp = ktime_get(); | |
105 | p->saddr = inet->saddr; | |
106 | p->sport = inet->sport; | |
107 | p->daddr = inet->daddr; | |
108 | p->dport = inet->dport; | |
109 | p->length = skb->len; | |
110 | p->snd_nxt = tp->snd_nxt; | |
111 | p->snd_una = tp->snd_una; | |
112 | p->snd_cwnd = tp->snd_cwnd; | |
113 | p->snd_wnd = tp->snd_wnd; | |
b3b0b681 | 114 | p->ssthresh = tcp_current_ssthresh(sk); |
662ad4f8 SH |
115 | p->srtt = tp->srtt >> 3; |
116 | ||
117 | tcp_probe.head = (tcp_probe.head + 1) % bufsize; | |
118 | } | |
119 | tcp_probe.lastcwnd = tp->snd_cwnd; | |
120 | spin_unlock(&tcp_probe.lock); | |
121 | ||
122 | wake_up(&tcp_probe.wait); | |
a42e9d6c SH |
123 | } |
124 | ||
125 | jprobe_return(); | |
126 | return 0; | |
127 | } | |
128 | ||
662ad4f8 | 129 | static struct jprobe tcp_jprobe = { |
3a872d89 | 130 | .kp = { |
85795d64 | 131 | .symbol_name = "tcp_rcv_established", |
3a872d89 | 132 | }, |
9e367d85 | 133 | .entry = jtcp_rcv_established, |
a42e9d6c SH |
134 | }; |
135 | ||
a42e9d6c SH |
136 | static int tcpprobe_open(struct inode * inode, struct file * file) |
137 | { | |
662ad4f8 SH |
138 | /* Reset (empty) log */ |
139 | spin_lock_bh(&tcp_probe.lock); | |
140 | tcp_probe.head = tcp_probe.tail = 0; | |
141 | tcp_probe.start = ktime_get(); | |
142 | spin_unlock_bh(&tcp_probe.lock); | |
143 | ||
a42e9d6c SH |
144 | return 0; |
145 | } | |
146 | ||
662ad4f8 SH |
147 | static int tcpprobe_sprint(char *tbuf, int n) |
148 | { | |
149 | const struct tcp_log *p | |
150 | = tcp_probe.log + tcp_probe.tail % bufsize; | |
151 | struct timespec tv | |
152 | = ktime_to_timespec(ktime_sub(p->tstamp, tcp_probe.start)); | |
153 | ||
154 | return snprintf(tbuf, n, | |
155 | "%lu.%09lu %d.%d.%d.%d:%u %d.%d.%d.%d:%u" | |
156 | " %d %#x %#x %u %u %u %u\n", | |
157 | (unsigned long) tv.tv_sec, | |
158 | (unsigned long) tv.tv_nsec, | |
159 | NIPQUAD(p->saddr), ntohs(p->sport), | |
160 | NIPQUAD(p->daddr), ntohs(p->dport), | |
161 | p->length, p->snd_nxt, p->snd_una, | |
162 | p->snd_cwnd, p->ssthresh, p->snd_wnd, p->srtt); | |
163 | } | |
164 | ||
a42e9d6c SH |
165 | static ssize_t tcpprobe_read(struct file *file, char __user *buf, |
166 | size_t len, loff_t *ppos) | |
167 | { | |
118075b3 | 168 | int error = 0, cnt = 0; |
a42e9d6c SH |
169 | |
170 | if (!buf || len < 0) | |
171 | return -EINVAL; | |
172 | ||
662ad4f8 SH |
173 | while (cnt < len) { |
174 | char tbuf[128]; | |
175 | int width; | |
176 | ||
177 | /* Wait for data in buffer */ | |
178 | error = wait_event_interruptible(tcp_probe.wait, | |
179 | tcp_probe_used() > 0); | |
180 | if (error) | |
181 | break; | |
a42e9d6c | 182 | |
662ad4f8 SH |
183 | spin_lock_bh(&tcp_probe.lock); |
184 | if (tcp_probe.head == tcp_probe.tail) { | |
185 | /* multiple readers race? */ | |
186 | spin_unlock_bh(&tcp_probe.lock); | |
187 | continue; | |
188 | } | |
a42e9d6c | 189 | |
662ad4f8 | 190 | width = tcpprobe_sprint(tbuf, sizeof(tbuf)); |
a42e9d6c | 191 | |
662ad4f8 SH |
192 | if (width < len) |
193 | tcp_probe.tail = (tcp_probe.tail + 1) % bufsize; | |
a42e9d6c | 194 | |
662ad4f8 SH |
195 | spin_unlock_bh(&tcp_probe.lock); |
196 | ||
197 | /* if record greater than space available | |
198 | return partial buffer (so far) */ | |
199 | if (width >= len) | |
200 | break; | |
201 | ||
202 | error = copy_to_user(buf + cnt, tbuf, width); | |
203 | if (error) | |
204 | break; | |
205 | cnt += width; | |
206 | } | |
a42e9d6c | 207 | |
662ad4f8 | 208 | return cnt == 0 ? error : cnt; |
a42e9d6c SH |
209 | } |
210 | ||
9a32144e | 211 | static const struct file_operations tcpprobe_fops = { |
a42e9d6c SH |
212 | .owner = THIS_MODULE, |
213 | .open = tcpprobe_open, | |
214 | .read = tcpprobe_read, | |
215 | }; | |
216 | ||
217 | static __init int tcpprobe_init(void) | |
218 | { | |
219 | int ret = -ENOMEM; | |
220 | ||
662ad4f8 SH |
221 | init_waitqueue_head(&tcp_probe.wait); |
222 | spin_lock_init(&tcp_probe.lock); | |
223 | ||
224 | if (bufsize < 0) | |
225 | return -EINVAL; | |
226 | ||
227 | tcp_probe.log = kcalloc(sizeof(struct tcp_log), bufsize, GFP_KERNEL); | |
228 | if (!tcp_probe.log) | |
229 | goto err0; | |
a42e9d6c SH |
230 | |
231 | if (!proc_net_fops_create(procname, S_IRUSR, &tcpprobe_fops)) | |
232 | goto err0; | |
233 | ||
662ad4f8 | 234 | ret = register_jprobe(&tcp_jprobe); |
a42e9d6c SH |
235 | if (ret) |
236 | goto err1; | |
237 | ||
662ad4f8 | 238 | pr_info("TCP probe registered (port=%d)\n", port); |
a42e9d6c SH |
239 | return 0; |
240 | err1: | |
241 | proc_net_remove(procname); | |
242 | err0: | |
662ad4f8 | 243 | kfree(tcp_probe.log); |
a42e9d6c SH |
244 | return ret; |
245 | } | |
246 | module_init(tcpprobe_init); | |
247 | ||
248 | static __exit void tcpprobe_exit(void) | |
249 | { | |
a42e9d6c | 250 | proc_net_remove(procname); |
662ad4f8 SH |
251 | unregister_jprobe(&tcp_jprobe); |
252 | kfree(tcp_probe.log); | |
a42e9d6c SH |
253 | } |
254 | module_exit(tcpprobe_exit); |