1/*
2 * dccp_probe - Observe the DCCP 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 * Modified for DCCP from Stephen Hemminger's code
8 * Copyright (C) 2006, Ian McDonald <ian.mcdonald@jandi.co.nz>
9 *
10 * This program is free software; you can redistribute it and/or modify
11 * it under the terms of the GNU General Public License as published by
12 * the Free Software Foundation; either version 2 of the License, or
13 * (at your option) any later version.
14 *
15 * This program is distributed in the hope that it will be useful,
16 * but WITHOUT ANY WARRANTY; without even the implied warranty of
17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
18 * GNU General Public License for more details.
19 *
20 * You should have received a copy of the GNU General Public License
21 * along with this program; if not, write to the Free Software
22 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
23 */
24
25#include <linux/kernel.h>
26#include <linux/kprobes.h>
27#include <linux/socket.h>
28#include <linux/dccp.h>
29#include <linux/proc_fs.h>
30#include <linux/module.h>
31#include <linux/kfifo.h>
32#include <linux/vmalloc.h>
33#include <linux/gfp.h>
34#include <net/net_namespace.h>
35
36#include "dccp.h"
37#include "ccid.h"
38#include "ccids/ccid3.h"
39
40static int port;
41
42static int bufsize = 64 * 1024;
43
44static const char procname[] = "dccpprobe";
45
46static struct {
47	struct kfifo	  fifo;
48	spinlock_t	  lock;
49	wait_queue_head_t wait;
50	struct timespec	  tstart;
51} dccpw;
52
53static void printl(const char *fmt, ...)
54{
55	va_list args;
56	int len;
57	struct timespec now;
58	char tbuf[256];
59
60	va_start(args, fmt);
61	getnstimeofday(&now);
62
63	now = timespec_sub(now, dccpw.tstart);
64
65	len = sprintf(tbuf, "%lu.%06lu ",
66		      (unsigned long) now.tv_sec,
67		      (unsigned long) now.tv_nsec / NSEC_PER_USEC);
68	len += vscnprintf(tbuf+len, sizeof(tbuf)-len, fmt, args);
69	va_end(args);
70
71	kfifo_in_locked(&dccpw.fifo, tbuf, len, &dccpw.lock);
72	wake_up(&dccpw.wait);
73}
74
75static int jdccp_sendmsg(struct sock *sk, struct msghdr *msg, size_t size)
76{
77	const struct inet_sock *inet = inet_sk(sk);
78	struct ccid3_hc_tx_sock *hc = NULL;
79
80	if (ccid_get_current_tx_ccid(dccp_sk(sk)) == DCCPC_CCID3)
81		hc = ccid3_hc_tx_sk(sk);
82
83	if (port == 0 || ntohs(inet->inet_dport) == port ||
84	    ntohs(inet->inet_sport) == port) {
85		if (hc)
86			printl("%pI4:%u %pI4:%u %d %d %d %d %u %llu %llu %d\n",
87			       &inet->inet_saddr, ntohs(inet->inet_sport),
88			       &inet->inet_daddr, ntohs(inet->inet_dport), size,
89			       hc->tx_s, hc->tx_rtt, hc->tx_p,
90			       hc->tx_x_calc, hc->tx_x_recv >> 6,
91			       hc->tx_x >> 6, hc->tx_t_ipi);
92		else
93			printl("%pI4:%u %pI4:%u %d\n",
94			       &inet->inet_saddr, ntohs(inet->inet_sport),
95			       &inet->inet_daddr, ntohs(inet->inet_dport),
96			       size);
97	}
98
99	jprobe_return();
100	return 0;
101}
102
103static struct jprobe dccp_send_probe = {
104	.kp	= {
105		.symbol_name = "dccp_sendmsg",
106	},
107	.entry	= jdccp_sendmsg,
108};
109
110static int dccpprobe_open(struct inode *inode, struct file *file)
111{
112	kfifo_reset(&dccpw.fifo);
113	getnstimeofday(&dccpw.tstart);
114	return 0;
115}
116
117static ssize_t dccpprobe_read(struct file *file, char __user *buf,
118			      size_t len, loff_t *ppos)
119{
120	int error = 0, cnt = 0;
121	unsigned char *tbuf;
122
123	if (!buf)
124		return -EINVAL;
125
126	if (len == 0)
127		return 0;
128
129	tbuf = vmalloc(len);
130	if (!tbuf)
131		return -ENOMEM;
132
133	error = wait_event_interruptible(dccpw.wait,
134					 kfifo_len(&dccpw.fifo) != 0);
135	if (error)
136		goto out_free;
137
138	cnt = kfifo_out_locked(&dccpw.fifo, tbuf, len, &dccpw.lock);
139	error = copy_to_user(buf, tbuf, cnt) ? -EFAULT : 0;
140
141out_free:
142	vfree(tbuf);
143
144	return error ? error : cnt;
145}
146
147static const struct file_operations dccpprobe_fops = {
148	.owner	 = THIS_MODULE,
149	.open	 = dccpprobe_open,
150	.read    = dccpprobe_read,
151	.llseek  = noop_llseek,
152};
153
154static __init int dccpprobe_init(void)
155{
156	int ret = -ENOMEM;
157
158	init_waitqueue_head(&dccpw.wait);
159	spin_lock_init(&dccpw.lock);
160	if (kfifo_alloc(&dccpw.fifo, bufsize, GFP_KERNEL))
161		return ret;
162	if (!proc_create(procname, S_IRUSR, init_net.proc_net, &dccpprobe_fops))
163		goto err0;
164
165	ret = register_jprobe(&dccp_send_probe);
166	if (ret) {
167		ret = request_module("dccp");
168		if (!ret)
169			ret = register_jprobe(&dccp_send_probe);
170	}
171
172	if (ret)
173		goto err1;
174
175	pr_info("DCCP watch registered (port=%d)\n", port);
176	return 0;
177err1:
178	remove_proc_entry(procname, init_net.proc_net);
179err0:
180	kfifo_free(&dccpw.fifo);
181	return ret;
182}
183module_init(dccpprobe_init);
184
185static __exit void dccpprobe_exit(void)
186{
187	kfifo_free(&dccpw.fifo);
188	remove_proc_entry(procname, init_net.proc_net);
189	unregister_jprobe(&dccp_send_probe);
190
191}
192module_exit(dccpprobe_exit);
193
194MODULE_PARM_DESC(port, "Port to match (0=all)");
195module_param(port, int, 0);
196
197MODULE_PARM_DESC(bufsize, "Log buffer size (default 64k)");
198module_param(bufsize, int, 0);
199
200MODULE_AUTHOR("Ian McDonald <ian.mcdonald@jandi.co.nz>");
201MODULE_DESCRIPTION("DCCP snooper");
202MODULE_LICENSE("GPL");
203