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Stephen Hemmingera42e9d62006-06-05 17:30:32 -07001/*
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
Stephen Hemminger662ad4f2007-07-11 19:43:52 -07009 * the Free Software Foundation; either version 2 of the License.
Stephen Hemmingera42e9d62006-06-05 17:30:32 -070010 *
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>
Stephen Hemminger85795d62007-03-24 21:35:33 -070027#include <linux/ktime.h>
28#include <linux/time.h>
Eric W. Biederman457c4cb2007-09-12 12:01:34 +020029#include <net/net_namespace.h>
Stephen Hemmingera42e9d62006-06-05 17:30:32 -070030
31#include <net/tcp.h>
32
Stephen Hemminger65ebe6342007-01-23 11:38:57 -080033MODULE_AUTHOR("Stephen Hemminger <shemminger@linux-foundation.org>");
Stephen Hemmingera42e9d62006-06-05 17:30:32 -070034MODULE_DESCRIPTION("TCP cwnd snooper");
35MODULE_LICENSE("GPL");
Stephen Hemminger662ad4f2007-07-11 19:43:52 -070036MODULE_VERSION("1.1");
Stephen Hemmingera42e9d62006-06-05 17:30:32 -070037
Stephen Hemminger85795d62007-03-24 21:35:33 -070038static int port __read_mostly = 0;
Stephen Hemmingera42e9d62006-06-05 17:30:32 -070039MODULE_PARM_DESC(port, "Port to match (0=all)");
40module_param(port, int, 0);
41
Stephen Hemminger662ad4f2007-07-11 19:43:52 -070042static int bufsize __read_mostly = 4096;
43MODULE_PARM_DESC(bufsize, "Log buffer size in packets (4096)");
Stephen Hemmingera42e9d62006-06-05 17:30:32 -070044module_param(bufsize, int, 0);
45
Stephen Hemminger85795d62007-03-24 21:35:33 -070046static int full __read_mostly;
47MODULE_PARM_DESC(full, "Full log (1=every ack packet received, 0=only cwnd changes)");
48module_param(full, int, 0);
49
Stephen Hemmingera42e9d62006-06-05 17:30:32 -070050static const char procname[] = "tcpprobe";
51
Stephen Hemminger662ad4f2007-07-11 19:43:52 -070052struct tcp_log {
53 ktime_t tstamp;
54 __be32 saddr, daddr;
55 __be16 sport, dport;
56 u16 length;
57 u32 snd_nxt;
58 u32 snd_una;
59 u32 snd_wnd;
60 u32 snd_cwnd;
61 u32 ssthresh;
62 u32 srtt;
63};
64
65static struct {
Stephen Hemminger85795d62007-03-24 21:35:33 -070066 spinlock_t lock;
Stephen Hemmingera42e9d62006-06-05 17:30:32 -070067 wait_queue_head_t wait;
Stephen Hemminger85795d62007-03-24 21:35:33 -070068 ktime_t start;
69 u32 lastcwnd;
Stephen Hemmingera42e9d62006-06-05 17:30:32 -070070
Stephen Hemminger662ad4f2007-07-11 19:43:52 -070071 unsigned long head, tail;
72 struct tcp_log *log;
73} tcp_probe;
David S. Miller14a49e12007-06-05 00:19:24 -070074
Stephen Hemminger662ad4f2007-07-11 19:43:52 -070075
76static inline int tcp_probe_used(void)
Stephen Hemmingera42e9d62006-06-05 17:30:32 -070077{
Stephen Hemminger662ad4f2007-07-11 19:43:52 -070078 return (tcp_probe.head - tcp_probe.tail) % bufsize;
79}
Stephen Hemmingera42e9d62006-06-05 17:30:32 -070080
Stephen Hemminger662ad4f2007-07-11 19:43:52 -070081static inline int tcp_probe_avail(void)
82{
83 return bufsize - tcp_probe_used();
David S. Miller14a49e12007-06-05 00:19:24 -070084}
Stephen Hemmingera42e9d62006-06-05 17:30:32 -070085
Stephen Hemminger85795d62007-03-24 21:35:33 -070086/*
87 * Hook inserted to be called before each receive packet.
88 * Note: arguments must match tcp_rcv_established()!
89 */
90static int jtcp_rcv_established(struct sock *sk, struct sk_buff *skb,
91 struct tcphdr *th, unsigned len)
Stephen Hemmingera42e9d62006-06-05 17:30:32 -070092{
93 const struct tcp_sock *tp = tcp_sk(sk);
94 const struct inet_sock *inet = inet_sk(sk);
95
Stephen Hemminger85795d62007-03-24 21:35:33 -070096 /* Only update if port matches */
97 if ((port == 0 || ntohs(inet->dport) == port || ntohs(inet->sport) == port)
Stephen Hemminger662ad4f2007-07-11 19:43:52 -070098 && (full || tp->snd_cwnd != tcp_probe.lastcwnd)) {
99
100 spin_lock(&tcp_probe.lock);
101 /* If log fills, just silently drop */
102 if (tcp_probe_avail() > 1) {
103 struct tcp_log *p = tcp_probe.log + tcp_probe.head;
104
105 p->tstamp = ktime_get();
106 p->saddr = inet->saddr;
107 p->sport = inet->sport;
108 p->daddr = inet->daddr;
109 p->dport = inet->dport;
110 p->length = skb->len;
111 p->snd_nxt = tp->snd_nxt;
112 p->snd_una = tp->snd_una;
113 p->snd_cwnd = tp->snd_cwnd;
114 p->snd_wnd = tp->snd_wnd;
Stephen Hemmingerb3b0b682007-07-14 18:57:19 -0700115 p->ssthresh = tcp_current_ssthresh(sk);
Stephen Hemminger662ad4f2007-07-11 19:43:52 -0700116 p->srtt = tp->srtt >> 3;
117
118 tcp_probe.head = (tcp_probe.head + 1) % bufsize;
119 }
120 tcp_probe.lastcwnd = tp->snd_cwnd;
121 spin_unlock(&tcp_probe.lock);
122
123 wake_up(&tcp_probe.wait);
Stephen Hemmingera42e9d62006-06-05 17:30:32 -0700124 }
125
126 jprobe_return();
127 return 0;
128}
129
Stephen Hemminger662ad4f2007-07-11 19:43:52 -0700130static struct jprobe tcp_jprobe = {
Ananth N Mavinakayanahalli3a872d82006-10-02 02:17:30 -0700131 .kp = {
Stephen Hemminger85795d62007-03-24 21:35:33 -0700132 .symbol_name = "tcp_rcv_established",
Ananth N Mavinakayanahalli3a872d82006-10-02 02:17:30 -0700133 },
Michael Ellerman9e367d82007-07-19 01:48:10 -0700134 .entry = jtcp_rcv_established,
Stephen Hemmingera42e9d62006-06-05 17:30:32 -0700135};
136
Stephen Hemmingera42e9d62006-06-05 17:30:32 -0700137static int tcpprobe_open(struct inode * inode, struct file * file)
138{
Stephen Hemminger662ad4f2007-07-11 19:43:52 -0700139 /* Reset (empty) log */
140 spin_lock_bh(&tcp_probe.lock);
141 tcp_probe.head = tcp_probe.tail = 0;
142 tcp_probe.start = ktime_get();
143 spin_unlock_bh(&tcp_probe.lock);
144
Stephen Hemmingera42e9d62006-06-05 17:30:32 -0700145 return 0;
146}
147
Stephen Hemminger662ad4f2007-07-11 19:43:52 -0700148static int tcpprobe_sprint(char *tbuf, int n)
149{
150 const struct tcp_log *p
151 = tcp_probe.log + tcp_probe.tail % bufsize;
152 struct timespec tv
153 = ktime_to_timespec(ktime_sub(p->tstamp, tcp_probe.start));
154
155 return snprintf(tbuf, n,
156 "%lu.%09lu %d.%d.%d.%d:%u %d.%d.%d.%d:%u"
157 " %d %#x %#x %u %u %u %u\n",
158 (unsigned long) tv.tv_sec,
159 (unsigned long) tv.tv_nsec,
160 NIPQUAD(p->saddr), ntohs(p->sport),
161 NIPQUAD(p->daddr), ntohs(p->dport),
162 p->length, p->snd_nxt, p->snd_una,
163 p->snd_cwnd, p->ssthresh, p->snd_wnd, p->srtt);
164}
165
Stephen Hemmingera42e9d62006-06-05 17:30:32 -0700166static ssize_t tcpprobe_read(struct file *file, char __user *buf,
167 size_t len, loff_t *ppos)
168{
James Morris118075b2006-07-30 20:21:45 -0700169 int error = 0, cnt = 0;
Stephen Hemmingera42e9d62006-06-05 17:30:32 -0700170
171 if (!buf || len < 0)
172 return -EINVAL;
173
Stephen Hemminger662ad4f2007-07-11 19:43:52 -0700174 while (cnt < len) {
175 char tbuf[128];
176 int width;
Stephen Hemmingera42e9d62006-06-05 17:30:32 -0700177
Stephen Hemminger662ad4f2007-07-11 19:43:52 -0700178 /* Wait for data in buffer */
179 error = wait_event_interruptible(tcp_probe.wait,
180 tcp_probe_used() > 0);
181 if (error)
182 break;
Stephen Hemmingera42e9d62006-06-05 17:30:32 -0700183
Stephen Hemminger662ad4f2007-07-11 19:43:52 -0700184 spin_lock_bh(&tcp_probe.lock);
185 if (tcp_probe.head == tcp_probe.tail) {
186 /* multiple readers race? */
187 spin_unlock_bh(&tcp_probe.lock);
188 continue;
189 }
Stephen Hemmingera42e9d62006-06-05 17:30:32 -0700190
Stephen Hemminger662ad4f2007-07-11 19:43:52 -0700191 width = tcpprobe_sprint(tbuf, sizeof(tbuf));
Stephen Hemmingera42e9d62006-06-05 17:30:32 -0700192
Stephen Hemminger662ad4f2007-07-11 19:43:52 -0700193 if (width < len)
194 tcp_probe.tail = (tcp_probe.tail + 1) % bufsize;
Stephen Hemmingera42e9d62006-06-05 17:30:32 -0700195
Stephen Hemminger662ad4f2007-07-11 19:43:52 -0700196 spin_unlock_bh(&tcp_probe.lock);
197
198 /* if record greater than space available
199 return partial buffer (so far) */
200 if (width >= len)
201 break;
202
203 error = copy_to_user(buf + cnt, tbuf, width);
204 if (error)
205 break;
206 cnt += width;
207 }
208
209 return cnt == 0 ? error : cnt;
Stephen Hemmingera42e9d62006-06-05 17:30:32 -0700210}
211
Arjan van de Ven9a321442007-02-12 00:55:35 -0800212static const struct file_operations tcpprobe_fops = {
Stephen Hemmingera42e9d62006-06-05 17:30:32 -0700213 .owner = THIS_MODULE,
214 .open = tcpprobe_open,
215 .read = tcpprobe_read,
216};
217
218static __init int tcpprobe_init(void)
219{
220 int ret = -ENOMEM;
221
Stephen Hemminger662ad4f2007-07-11 19:43:52 -0700222 init_waitqueue_head(&tcp_probe.wait);
223 spin_lock_init(&tcp_probe.lock);
224
225 if (bufsize < 0)
226 return -EINVAL;
227
228 tcp_probe.log = kcalloc(sizeof(struct tcp_log), bufsize, GFP_KERNEL);
229 if (!tcp_probe.log)
230 goto err0;
Stephen Hemmingera42e9d62006-06-05 17:30:32 -0700231
Eric W. Biederman457c4cb2007-09-12 12:01:34 +0200232 if (!proc_net_fops_create(&init_net, procname, S_IRUSR, &tcpprobe_fops))
Stephen Hemmingera42e9d62006-06-05 17:30:32 -0700233 goto err0;
234
Stephen Hemminger662ad4f2007-07-11 19:43:52 -0700235 ret = register_jprobe(&tcp_jprobe);
Stephen Hemmingera42e9d62006-06-05 17:30:32 -0700236 if (ret)
237 goto err1;
238
Stephen Hemminger662ad4f2007-07-11 19:43:52 -0700239 pr_info("TCP probe registered (port=%d)\n", port);
Stephen Hemmingera42e9d62006-06-05 17:30:32 -0700240 return 0;
241 err1:
Eric W. Biederman457c4cb2007-09-12 12:01:34 +0200242 proc_net_remove(&init_net, procname);
Stephen Hemmingera42e9d62006-06-05 17:30:32 -0700243 err0:
Stephen Hemminger662ad4f2007-07-11 19:43:52 -0700244 kfree(tcp_probe.log);
Stephen Hemmingera42e9d62006-06-05 17:30:32 -0700245 return ret;
246}
247module_init(tcpprobe_init);
248
249static __exit void tcpprobe_exit(void)
250{
Eric W. Biederman457c4cb2007-09-12 12:01:34 +0200251 proc_net_remove(&init_net, procname);
Stephen Hemminger662ad4f2007-07-11 19:43:52 -0700252 unregister_jprobe(&tcp_jprobe);
253 kfree(tcp_probe.log);
Stephen Hemmingera42e9d62006-06-05 17:30:32 -0700254}
255module_exit(tcpprobe_exit);