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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 | |
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 | ||
33 | MODULE_AUTHOR("Stephen Hemminger <shemminger@osdl.org>"); | |
34 | MODULE_DESCRIPTION("TCP cwnd snooper"); | |
35 | MODULE_LICENSE("GPL"); | |
36 | ||
37 | static int port = 0; | |
38 | MODULE_PARM_DESC(port, "Port to match (0=all)"); | |
39 | module_param(port, int, 0); | |
40 | ||
41 | static int bufsize = 64*1024; | |
42 | MODULE_PARM_DESC(bufsize, "Log buffer size (default 64k)"); | |
43 | module_param(bufsize, int, 0); | |
44 | ||
45 | static const char procname[] = "tcpprobe"; | |
46 | ||
47 | struct { | |
48 | struct kfifo *fifo; | |
49 | spinlock_t lock; | |
50 | wait_queue_head_t wait; | |
51 | struct timeval tstart; | |
52 | } tcpw; | |
53 | ||
54 | static 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 | ||
70df2311 DM |
71 | len = sprintf(tbuf, "%lu.%06lu ", |
72 | (unsigned long) now.tv_sec, | |
73 | (unsigned long) now.tv_usec); | |
a42e9d6c SH |
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 | ||
81 | static 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 | ||
101 | static struct jprobe tcp_send_probe = { | |
102 | .kp = { .addr = (kprobe_opcode_t *) &tcp_sendmsg, }, | |
103 | .entry = (kprobe_opcode_t *) &jtcp_sendmsg, | |
104 | }; | |
105 | ||
106 | ||
107 | static 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 | ||
114 | static ssize_t tcpprobe_read(struct file *file, char __user *buf, | |
115 | size_t len, loff_t *ppos) | |
116 | { | |
118075b3 | 117 | int error = 0, cnt = 0; |
a42e9d6c SH |
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 | ||
143 | static struct file_operations tcpprobe_fops = { | |
144 | .owner = THIS_MODULE, | |
145 | .open = tcpprobe_open, | |
146 | .read = tcpprobe_read, | |
147 | }; | |
148 | ||
149 | static __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 | } | |
172 | module_init(tcpprobe_init); | |
173 | ||
174 | static __exit void tcpprobe_exit(void) | |
175 | { | |
176 | kfifo_free(tcpw.fifo); | |
177 | proc_net_remove(procname); | |
178 | unregister_jprobe(&tcp_send_probe); | |
179 | ||
180 | } | |
181 | module_exit(tcpprobe_exit); |