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 kiocb *iocb, struct sock *sk,
 76			 struct msghdr *msg, size_t size)
 77{
 78	const struct inet_sock *inet = inet_sk(sk);
 79	struct ccid3_hc_tx_sock *hc = NULL;
 80
 81	if (ccid_get_current_tx_ccid(dccp_sk(sk)) == DCCPC_CCID3)
 82		hc = ccid3_hc_tx_sk(sk);
 83
 84	if (port == 0 || ntohs(inet->inet_dport) == port ||
 85	    ntohs(inet->inet_sport) == port) {
 86		if (hc)
 87			printl("%pI4:%u %pI4:%u %d %d %d %d %u %llu %llu %d\n",
 88			       &inet->inet_saddr, ntohs(inet->inet_sport),
 89			       &inet->inet_daddr, ntohs(inet->inet_dport), size,
 90			       hc->tx_s, hc->tx_rtt, hc->tx_p,
 91			       hc->tx_x_calc, hc->tx_x_recv >> 6,
 92			       hc->tx_x >> 6, hc->tx_t_ipi);
 93		else
 94			printl("%pI4:%u %pI4:%u %d\n",
 95			       &inet->inet_saddr, ntohs(inet->inet_sport),
 96			       &inet->inet_daddr, ntohs(inet->inet_dport),
 97			       size);
 98	}
 99
100	jprobe_return();
101	return 0;
102}
103
104static struct jprobe dccp_send_probe = {
105	.kp	= {
106		.symbol_name = "dccp_sendmsg",
107	},
108	.entry	= jdccp_sendmsg,
109};
110
111static int dccpprobe_open(struct inode *inode, struct file *file)
112{
113	kfifo_reset(&dccpw.fifo);
114	getnstimeofday(&dccpw.tstart);
115	return 0;
116}
117
118static ssize_t dccpprobe_read(struct file *file, char __user *buf,
119			      size_t len, loff_t *ppos)
120{
121	int error = 0, cnt = 0;
122	unsigned char *tbuf;
123
124	if (!buf)
125		return -EINVAL;
126
127	if (len == 0)
128		return 0;
129
130	tbuf = vmalloc(len);
131	if (!tbuf)
132		return -ENOMEM;
133
134	error = wait_event_interruptible(dccpw.wait,
135					 kfifo_len(&dccpw.fifo) != 0);
136	if (error)
137		goto out_free;
138
139	cnt = kfifo_out_locked(&dccpw.fifo, tbuf, len, &dccpw.lock);
140	error = copy_to_user(buf, tbuf, cnt) ? -EFAULT : 0;
141
142out_free:
143	vfree(tbuf);
144
145	return error ? error : cnt;
146}
147
148static const struct file_operations dccpprobe_fops = {
149	.owner	 = THIS_MODULE,
150	.open	 = dccpprobe_open,
151	.read    = dccpprobe_read,
152	.llseek  = noop_llseek,
153};
154
155static __init int dccpprobe_init(void)
156{
157	int ret = -ENOMEM;
158
159	init_waitqueue_head(&dccpw.wait);
160	spin_lock_init(&dccpw.lock);
161	if (kfifo_alloc(&dccpw.fifo, bufsize, GFP_KERNEL))
162		return ret;
163	if (!proc_net_fops_create(&init_net, procname, S_IRUSR, &dccpprobe_fops))
164		goto err0;
165
166	try_then_request_module((ret = register_jprobe(&dccp_send_probe)) == 0,
167				"dccp");
168	if (ret)
169		goto err1;
170
171	pr_info("DCCP watch registered (port=%d)\n", port);
172	return 0;
173err1:
174	proc_net_remove(&init_net, procname);
175err0:
176	kfifo_free(&dccpw.fifo);
177	return ret;
178}
179module_init(dccpprobe_init);
180
181static __exit void dccpprobe_exit(void)
182{
183	kfifo_free(&dccpw.fifo);
184	proc_net_remove(&init_net, procname);
185	unregister_jprobe(&dccp_send_probe);
186
187}
188module_exit(dccpprobe_exit);
189
190MODULE_PARM_DESC(port, "Port to match (0=all)");
191module_param(port, int, 0);
192
193MODULE_PARM_DESC(bufsize, "Log buffer size (default 64k)");
194module_param(bufsize, int, 0);
195
196MODULE_AUTHOR("Ian McDonald <ian.mcdonald@jandi.co.nz>");
197MODULE_DESCRIPTION("DCCP snooper");
198MODULE_LICENSE("GPL");