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 | |
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> | |
85795d64 SH |
29 | #include <linux/ktime.h> |
30 | #include <linux/time.h> | |
a42e9d6c SH |
31 | #include <linux/vmalloc.h> |
32 | ||
33 | #include <net/tcp.h> | |
34 | ||
65ebe634 | 35 | MODULE_AUTHOR("Stephen Hemminger <shemminger@linux-foundation.org>"); |
a42e9d6c SH |
36 | MODULE_DESCRIPTION("TCP cwnd snooper"); |
37 | MODULE_LICENSE("GPL"); | |
38 | ||
85795d64 | 39 | static int port __read_mostly = 0; |
a42e9d6c SH |
40 | MODULE_PARM_DESC(port, "Port to match (0=all)"); |
41 | module_param(port, int, 0); | |
42 | ||
85795d64 | 43 | static int bufsize __read_mostly = 64*1024; |
a42e9d6c SH |
44 | MODULE_PARM_DESC(bufsize, "Log buffer size (default 64k)"); |
45 | module_param(bufsize, int, 0); | |
46 | ||
85795d64 SH |
47 | static int full __read_mostly; |
48 | MODULE_PARM_DESC(full, "Full log (1=every ack packet received, 0=only cwnd changes)"); | |
49 | module_param(full, int, 0); | |
50 | ||
a42e9d6c SH |
51 | static const char procname[] = "tcpprobe"; |
52 | ||
53 | struct { | |
85795d64 SH |
54 | struct kfifo *fifo; |
55 | spinlock_t lock; | |
a42e9d6c | 56 | wait_queue_head_t wait; |
85795d64 SH |
57 | ktime_t start; |
58 | u32 lastcwnd; | |
a42e9d6c SH |
59 | } tcpw; |
60 | ||
85795d64 SH |
61 | /* |
62 | * Print to log with timestamps. | |
63 | * FIXME: causes an extra copy | |
64 | */ | |
a42e9d6c SH |
65 | static void printl(const char *fmt, ...) |
66 | { | |
67 | va_list args; | |
68 | int len; | |
85795d64 | 69 | struct timespec tv; |
a42e9d6c SH |
70 | char tbuf[256]; |
71 | ||
72 | va_start(args, fmt); | |
85795d64 SH |
73 | /* want monotonic time since start of tcp_probe */ |
74 | tv = ktime_to_timespec(ktime_sub(ktime_get(), tcpw.start)); | |
a42e9d6c | 75 | |
85795d64 SH |
76 | len = sprintf(tbuf, "%lu.%09lu ", |
77 | (unsigned long) tv.tv_sec, (unsigned long) tv.tv_nsec); | |
a42e9d6c SH |
78 | len += vscnprintf(tbuf+len, sizeof(tbuf)-len, fmt, args); |
79 | va_end(args); | |
80 | ||
81 | kfifo_put(tcpw.fifo, tbuf, len); | |
82 | wake_up(&tcpw.wait); | |
67403754 SH |
83 | } __attribute__ ((format (printf, 1, 2))); |
84 | ||
a42e9d6c | 85 | |
85795d64 SH |
86 | /* |
87 | * Hook inserted to be called before each receive packet. | |
88 | * Note: arguments must match tcp_rcv_established()! | |
89 | */ | |
90 | static int jtcp_rcv_established(struct sock *sk, struct sk_buff *skb, | |
91 | struct tcphdr *th, unsigned len) | |
a42e9d6c SH |
92 | { |
93 | const struct tcp_sock *tp = tcp_sk(sk); | |
94 | const struct inet_sock *inet = inet_sk(sk); | |
95 | ||
85795d64 SH |
96 | /* Only update if port matches */ |
97 | if ((port == 0 || ntohs(inet->dport) == port || ntohs(inet->sport) == port) | |
98 | && (full || tp->snd_cwnd != tcpw.lastcwnd)) { | |
63313494 | 99 | printl("%d.%d.%d.%d:%u %d.%d.%d.%d:%u %d %#x %#x %u %u %u %u\n", |
a42e9d6c SH |
100 | NIPQUAD(inet->saddr), ntohs(inet->sport), |
101 | NIPQUAD(inet->daddr), ntohs(inet->dport), | |
85795d64 | 102 | skb->len, tp->snd_nxt, tp->snd_una, |
a42e9d6c | 103 | tp->snd_cwnd, tcp_current_ssthresh(sk), |
85795d64 SH |
104 | tp->snd_wnd, tp->srtt >> 3); |
105 | tcpw.lastcwnd = tp->snd_cwnd; | |
a42e9d6c SH |
106 | } |
107 | ||
108 | jprobe_return(); | |
109 | return 0; | |
110 | } | |
111 | ||
85795d64 | 112 | static struct jprobe tcp_probe = { |
3a872d89 | 113 | .kp = { |
85795d64 | 114 | .symbol_name = "tcp_rcv_established", |
3a872d89 | 115 | }, |
85795d64 | 116 | .entry = JPROBE_ENTRY(jtcp_rcv_established), |
a42e9d6c SH |
117 | }; |
118 | ||
119 | ||
120 | static int tcpprobe_open(struct inode * inode, struct file * file) | |
121 | { | |
122 | kfifo_reset(tcpw.fifo); | |
85795d64 | 123 | tcpw.start = ktime_get(); |
a42e9d6c SH |
124 | return 0; |
125 | } | |
126 | ||
127 | static ssize_t tcpprobe_read(struct file *file, char __user *buf, | |
128 | size_t len, loff_t *ppos) | |
129 | { | |
118075b3 | 130 | int error = 0, cnt = 0; |
a42e9d6c SH |
131 | unsigned char *tbuf; |
132 | ||
133 | if (!buf || len < 0) | |
134 | return -EINVAL; | |
135 | ||
136 | if (len == 0) | |
137 | return 0; | |
138 | ||
139 | tbuf = vmalloc(len); | |
140 | if (!tbuf) | |
141 | return -ENOMEM; | |
142 | ||
143 | error = wait_event_interruptible(tcpw.wait, | |
144 | __kfifo_len(tcpw.fifo) != 0); | |
145 | if (error) | |
18b6fe64 | 146 | goto out_free; |
a42e9d6c SH |
147 | |
148 | cnt = kfifo_get(tcpw.fifo, tbuf, len); | |
149 | error = copy_to_user(buf, tbuf, cnt); | |
150 | ||
18b6fe64 | 151 | out_free: |
a42e9d6c SH |
152 | vfree(tbuf); |
153 | ||
154 | return error ? error : cnt; | |
155 | } | |
156 | ||
9a32144e | 157 | static const struct file_operations tcpprobe_fops = { |
a42e9d6c SH |
158 | .owner = THIS_MODULE, |
159 | .open = tcpprobe_open, | |
160 | .read = tcpprobe_read, | |
161 | }; | |
162 | ||
163 | static __init int tcpprobe_init(void) | |
164 | { | |
165 | int ret = -ENOMEM; | |
166 | ||
167 | init_waitqueue_head(&tcpw.wait); | |
168 | spin_lock_init(&tcpw.lock); | |
169 | tcpw.fifo = kfifo_alloc(bufsize, GFP_KERNEL, &tcpw.lock); | |
ac16ca64 AM |
170 | if (IS_ERR(tcpw.fifo)) |
171 | return PTR_ERR(tcpw.fifo); | |
a42e9d6c SH |
172 | |
173 | if (!proc_net_fops_create(procname, S_IRUSR, &tcpprobe_fops)) | |
174 | goto err0; | |
175 | ||
85795d64 | 176 | ret = register_jprobe(&tcp_probe); |
a42e9d6c SH |
177 | if (ret) |
178 | goto err1; | |
179 | ||
180 | pr_info("TCP watch registered (port=%d)\n", port); | |
181 | return 0; | |
182 | err1: | |
183 | proc_net_remove(procname); | |
184 | err0: | |
185 | kfifo_free(tcpw.fifo); | |
186 | return ret; | |
187 | } | |
188 | module_init(tcpprobe_init); | |
189 | ||
190 | static __exit void tcpprobe_exit(void) | |
191 | { | |
192 | kfifo_free(tcpw.fifo); | |
193 | proc_net_remove(procname); | |
85795d64 | 194 | unregister_jprobe(&tcp_probe); |
a42e9d6c SH |
195 | |
196 | } | |
197 | module_exit(tcpprobe_exit); |