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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 | ||
71 | len = sprintf(tbuf, "%lu.%06lu ", now.tv_sec, now.tv_usec); | |
72 | len += vscnprintf(tbuf+len, sizeof(tbuf)-len, fmt, args); | |
73 | va_end(args); | |
74 | ||
75 | kfifo_put(tcpw.fifo, tbuf, len); | |
76 | wake_up(&tcpw.wait); | |
77 | } | |
78 | ||
79 | static int jtcp_sendmsg(struct kiocb *iocb, struct sock *sk, | |
80 | struct msghdr *msg, size_t size) | |
81 | { | |
82 | const struct tcp_sock *tp = tcp_sk(sk); | |
83 | const struct inet_sock *inet = inet_sk(sk); | |
84 | ||
85 | if (port == 0 || ntohs(inet->dport) == port || | |
86 | ntohs(inet->sport) == port) { | |
87 | printl("%d.%d.%d.%d:%u %d.%d.%d.%d:%u %d %#x %#x %u %u %u\n", | |
88 | NIPQUAD(inet->saddr), ntohs(inet->sport), | |
89 | NIPQUAD(inet->daddr), ntohs(inet->dport), | |
90 | size, tp->snd_nxt, tp->snd_una, | |
91 | tp->snd_cwnd, tcp_current_ssthresh(sk), | |
92 | tp->snd_wnd); | |
93 | } | |
94 | ||
95 | jprobe_return(); | |
96 | return 0; | |
97 | } | |
98 | ||
99 | static struct jprobe tcp_send_probe = { | |
100 | .kp = { .addr = (kprobe_opcode_t *) &tcp_sendmsg, }, | |
101 | .entry = (kprobe_opcode_t *) &jtcp_sendmsg, | |
102 | }; | |
103 | ||
104 | ||
105 | static int tcpprobe_open(struct inode * inode, struct file * file) | |
106 | { | |
107 | kfifo_reset(tcpw.fifo); | |
108 | do_gettimeofday(&tcpw.tstart); | |
109 | return 0; | |
110 | } | |
111 | ||
112 | static ssize_t tcpprobe_read(struct file *file, char __user *buf, | |
113 | size_t len, loff_t *ppos) | |
114 | { | |
115 | int error = 0, cnt; | |
116 | unsigned char *tbuf; | |
117 | ||
118 | if (!buf || len < 0) | |
119 | return -EINVAL; | |
120 | ||
121 | if (len == 0) | |
122 | return 0; | |
123 | ||
124 | tbuf = vmalloc(len); | |
125 | if (!tbuf) | |
126 | return -ENOMEM; | |
127 | ||
128 | error = wait_event_interruptible(tcpw.wait, | |
129 | __kfifo_len(tcpw.fifo) != 0); | |
130 | if (error) | |
131 | return error; | |
132 | ||
133 | cnt = kfifo_get(tcpw.fifo, tbuf, len); | |
134 | error = copy_to_user(buf, tbuf, cnt); | |
135 | ||
136 | vfree(tbuf); | |
137 | ||
138 | return error ? error : cnt; | |
139 | } | |
140 | ||
141 | static struct file_operations tcpprobe_fops = { | |
142 | .owner = THIS_MODULE, | |
143 | .open = tcpprobe_open, | |
144 | .read = tcpprobe_read, | |
145 | }; | |
146 | ||
147 | static __init int tcpprobe_init(void) | |
148 | { | |
149 | int ret = -ENOMEM; | |
150 | ||
151 | init_waitqueue_head(&tcpw.wait); | |
152 | spin_lock_init(&tcpw.lock); | |
153 | tcpw.fifo = kfifo_alloc(bufsize, GFP_KERNEL, &tcpw.lock); | |
154 | ||
155 | if (!proc_net_fops_create(procname, S_IRUSR, &tcpprobe_fops)) | |
156 | goto err0; | |
157 | ||
158 | ret = register_jprobe(&tcp_send_probe); | |
159 | if (ret) | |
160 | goto err1; | |
161 | ||
162 | pr_info("TCP watch registered (port=%d)\n", port); | |
163 | return 0; | |
164 | err1: | |
165 | proc_net_remove(procname); | |
166 | err0: | |
167 | kfifo_free(tcpw.fifo); | |
168 | return ret; | |
169 | } | |
170 | module_init(tcpprobe_init); | |
171 | ||
172 | static __exit void tcpprobe_exit(void) | |
173 | { | |
174 | kfifo_free(tcpw.fifo); | |
175 | proc_net_remove(procname); | |
176 | unregister_jprobe(&tcp_send_probe); | |
177 | ||
178 | } | |
179 | module_exit(tcpprobe_exit); |