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-rw-r--r--net/ipv4/tcp_probe.c181
1 files changed, 181 insertions, 0 deletions
diff --git a/net/ipv4/tcp_probe.c b/net/ipv4/tcp_probe.c
new file mode 100644
index 000000000000..d7d517a3a238
--- /dev/null
+++ b/net/ipv4/tcp_probe.c
@@ -0,0 +1,181 @@
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
9 * the Free Software Foundation; either version 2 of the License, or
10 * (at your option) any later version.
11 *
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, write to the Free Software
19 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
20 */
21
22#include <linux/kernel.h>
23#include <linux/kprobes.h>
24#include <linux/socket.h>
25#include <linux/tcp.h>
26#include <linux/proc_fs.h>
27#include <linux/module.h>
28#include <linux/kfifo.h>
29#include <linux/vmalloc.h>
30
31#include <net/tcp.h>
32
33MODULE_AUTHOR("Stephen Hemminger <shemminger@osdl.org>");
34MODULE_DESCRIPTION("TCP cwnd snooper");
35MODULE_LICENSE("GPL");
36
37static int port = 0;
38MODULE_PARM_DESC(port, "Port to match (0=all)");
39module_param(port, int, 0);
40
41static int bufsize = 64*1024;
42MODULE_PARM_DESC(bufsize, "Log buffer size (default 64k)");
43module_param(bufsize, int, 0);
44
45static const char procname[] = "tcpprobe";
46
47struct {
48 struct kfifo *fifo;
49 spinlock_t lock;
50 wait_queue_head_t wait;
51 struct timeval tstart;
52} tcpw;
53
54static void printl(const char *fmt, ...)
55{
56 va_list args;
57 int len;
58 struct timeval now;
59 char tbuf[256];
60
61 va_start(args, fmt);
62 do_gettimeofday(&now);
63
64 now.tv_sec -= tcpw.tstart.tv_sec;
65 now.tv_usec -= tcpw.tstart.tv_usec;
66 if (now.tv_usec < 0) {
67 --now.tv_sec;
68 now.tv_usec += 1000000;
69 }
70
71 len = sprintf(tbuf, "%lu.%06lu ",
72 (unsigned long) now.tv_sec,
73 (unsigned long) now.tv_usec);
74 len += vscnprintf(tbuf+len, sizeof(tbuf)-len, fmt, args);
75 va_end(args);
76
77 kfifo_put(tcpw.fifo, tbuf, len);
78 wake_up(&tcpw.wait);
79}
80
81static int jtcp_sendmsg(struct kiocb *iocb, struct sock *sk,
82 struct msghdr *msg, size_t size)
83{
84 const struct tcp_sock *tp = tcp_sk(sk);
85 const struct inet_sock *inet = inet_sk(sk);
86
87 if (port == 0 || ntohs(inet->dport) == port ||
88 ntohs(inet->sport) == port) {
89 printl("%d.%d.%d.%d:%u %d.%d.%d.%d:%u %d %#x %#x %u %u %u\n",
90 NIPQUAD(inet->saddr), ntohs(inet->sport),
91 NIPQUAD(inet->daddr), ntohs(inet->dport),
92 size, tp->snd_nxt, tp->snd_una,
93 tp->snd_cwnd, tcp_current_ssthresh(sk),
94 tp->snd_wnd);
95 }
96
97 jprobe_return();
98 return 0;
99}
100
101static struct jprobe tcp_send_probe = {
102 .kp = { .addr = (kprobe_opcode_t *) &tcp_sendmsg, },
103 .entry = (kprobe_opcode_t *) &jtcp_sendmsg,
104};
105
106
107static int tcpprobe_open(struct inode * inode, struct file * file)
108{
109 kfifo_reset(tcpw.fifo);
110 do_gettimeofday(&tcpw.tstart);
111 return 0;
112}
113
114static ssize_t tcpprobe_read(struct file *file, char __user *buf,
115 size_t len, loff_t *ppos)
116{
117 int error = 0, cnt;
118 unsigned char *tbuf;
119
120 if (!buf || len < 0)
121 return -EINVAL;
122
123 if (len == 0)
124 return 0;
125
126 tbuf = vmalloc(len);
127 if (!tbuf)
128 return -ENOMEM;
129
130 error = wait_event_interruptible(tcpw.wait,
131 __kfifo_len(tcpw.fifo) != 0);
132 if (error)
133 return error;
134
135 cnt = kfifo_get(tcpw.fifo, tbuf, len);
136 error = copy_to_user(buf, tbuf, cnt);
137
138 vfree(tbuf);
139
140 return error ? error : cnt;
141}
142
143static struct file_operations tcpprobe_fops = {
144 .owner = THIS_MODULE,
145 .open = tcpprobe_open,
146 .read = tcpprobe_read,
147};
148
149static __init int tcpprobe_init(void)
150{
151 int ret = -ENOMEM;
152
153 init_waitqueue_head(&tcpw.wait);
154 spin_lock_init(&tcpw.lock);
155 tcpw.fifo = kfifo_alloc(bufsize, GFP_KERNEL, &tcpw.lock);
156
157 if (!proc_net_fops_create(procname, S_IRUSR, &tcpprobe_fops))
158 goto err0;
159
160 ret = register_jprobe(&tcp_send_probe);
161 if (ret)
162 goto err1;
163
164 pr_info("TCP watch registered (port=%d)\n", port);
165 return 0;
166 err1:
167 proc_net_remove(procname);
168 err0:
169 kfifo_free(tcpw.fifo);
170 return ret;
171}
172module_init(tcpprobe_init);
173
174static __exit void tcpprobe_exit(void)
175{
176 kfifo_free(tcpw.fifo);
177 proc_net_remove(procname);
178 unregister_jprobe(&tcp_send_probe);
179
180}
181module_exit(tcpprobe_exit);