1/*
2 * sctp_probe - Observe the SCTP 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 SCTP from Stephen Hemminger's code
8 * Copyright (C) 2010, Wei Yongjun <yjwei@cn.fujitsu.com>
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
26
27#include <linux/kernel.h>
28#include <linux/kprobes.h>
29#include <linux/socket.h>
30#include <linux/sctp.h>
31#include <linux/proc_fs.h>
32#include <linux/vmalloc.h>
33#include <linux/module.h>
34#include <linux/kfifo.h>
35#include <linux/time.h>
36#include <net/net_namespace.h>
37
38#include <net/sctp/sctp.h>
39#include <net/sctp/sm.h>
40
41MODULE_SOFTDEP("pre: sctp");
42MODULE_AUTHOR("Wei Yongjun <yjwei@cn.fujitsu.com>");
43MODULE_DESCRIPTION("SCTP snooper");
44MODULE_LICENSE("GPL");
45
46static int port __read_mostly = 0;
47MODULE_PARM_DESC(port, "Port to match (0=all)");
48module_param(port, int, 0);
49
50static unsigned int fwmark __read_mostly = 0;
51MODULE_PARM_DESC(fwmark, "skb mark to match (0=no mark)");
52module_param(fwmark, uint, 0);
53
54static int bufsize __read_mostly = 64 * 1024;
55MODULE_PARM_DESC(bufsize, "Log buffer size (default 64k)");
56module_param(bufsize, int, 0);
57
58static int full __read_mostly = 1;
59MODULE_PARM_DESC(full, "Full log (1=every ack packet received,  0=only cwnd changes)");
60module_param(full, int, 0);
61
62static const char procname[] = "sctpprobe";
63
64static struct {
65	struct kfifo	  fifo;
66	spinlock_t	  lock;
67	wait_queue_head_t wait;
68	struct timespec	  tstart;
69} sctpw;
70
71static __printf(1, 2) void printl(const char *fmt, ...)
72{
73	va_list args;
74	int len;
75	char tbuf[256];
76
77	va_start(args, fmt);
78	len = vscnprintf(tbuf, sizeof(tbuf), fmt, args);
79	va_end(args);
80
81	kfifo_in_locked(&sctpw.fifo, tbuf, len, &sctpw.lock);
82	wake_up(&sctpw.wait);
83}
84
85static int sctpprobe_open(struct inode *inode, struct file *file)
86{
87	kfifo_reset(&sctpw.fifo);
88	getnstimeofday(&sctpw.tstart);
89
90	return 0;
91}
92
93static ssize_t sctpprobe_read(struct file *file, char __user *buf,
94			      size_t len, loff_t *ppos)
95{
96	int error = 0, cnt = 0;
97	unsigned char *tbuf;
98
99	if (!buf)
100		return -EINVAL;
101
102	if (len == 0)
103		return 0;
104
105	tbuf = vmalloc(len);
106	if (!tbuf)
107		return -ENOMEM;
108
109	error = wait_event_interruptible(sctpw.wait,
110					 kfifo_len(&sctpw.fifo) != 0);
111	if (error)
112		goto out_free;
113
114	cnt = kfifo_out_locked(&sctpw.fifo, tbuf, len, &sctpw.lock);
115	error = copy_to_user(buf, tbuf, cnt) ? -EFAULT : 0;
116
117out_free:
118	vfree(tbuf);
119
120	return error ? error : cnt;
121}
122
123static const struct file_operations sctpprobe_fops = {
124	.owner	= THIS_MODULE,
125	.open	= sctpprobe_open,
126	.read	= sctpprobe_read,
127	.llseek = noop_llseek,
128};
129
130static sctp_disposition_t jsctp_sf_eat_sack(struct net *net,
131					    const struct sctp_endpoint *ep,
132					    const struct sctp_association *asoc,
133					    const sctp_subtype_t type,
134					    void *arg,
135					    sctp_cmd_seq_t *commands)
136{
137	struct sctp_chunk *chunk = arg;
138	struct sk_buff *skb = chunk->skb;
139	struct sctp_transport *sp;
140	static __u32 lcwnd = 0;
141	struct timespec now;
142
143	sp = asoc->peer.primary_path;
144
145	if (((port == 0 && fwmark == 0) ||
146	     asoc->peer.port == port ||
147	     ep->base.bind_addr.port == port ||
148	     (fwmark > 0 && skb->mark == fwmark)) &&
149	    (full || sp->cwnd != lcwnd)) {
150		lcwnd = sp->cwnd;
151
152		getnstimeofday(&now);
153		now = timespec_sub(now, sctpw.tstart);
154
155		printl("%lu.%06lu ", (unsigned long) now.tv_sec,
156		       (unsigned long) now.tv_nsec / NSEC_PER_USEC);
157
158		printl("%p %5d %5d %5d %8d %5d ", asoc,
159		       ep->base.bind_addr.port, asoc->peer.port,
160		       asoc->pathmtu, asoc->peer.rwnd, asoc->unack_data);
161
162		list_for_each_entry(sp, &asoc->peer.transport_addr_list,
163					transports) {
164			if (sp == asoc->peer.primary_path)
165				printl("*");
166
167			printl("%pISc %2u %8u %8u %8u %8u %8u ",
168			       &sp->ipaddr, sp->state, sp->cwnd, sp->ssthresh,
169			       sp->flight_size, sp->partial_bytes_acked,
170			       sp->pathmtu);
171		}
172		printl("\n");
173	}
174
175	jprobe_return();
176	return 0;
177}
178
179static struct jprobe sctp_recv_probe = {
180	.kp	= {
181		.symbol_name = "sctp_sf_eat_sack_6_2",
182	},
183	.entry	= jsctp_sf_eat_sack,
184};
185
186static __init int sctp_setup_jprobe(void)
187{
188	int ret = register_jprobe(&sctp_recv_probe);
189
190	if (ret) {
191		if (request_module("sctp"))
192			goto out;
193		ret = register_jprobe(&sctp_recv_probe);
194	}
195
196out:
197	return ret;
198}
199
200static __init int sctpprobe_init(void)
201{
202	int ret = -ENOMEM;
203
204	/* Warning: if the function signature of sctp_sf_eat_sack_6_2,
205	 * has been changed, you also have to change the signature of
206	 * jsctp_sf_eat_sack, otherwise you end up right here!
207	 */
208	BUILD_BUG_ON(__same_type(sctp_sf_eat_sack_6_2,
209				 jsctp_sf_eat_sack) == 0);
210
211	init_waitqueue_head(&sctpw.wait);
212	spin_lock_init(&sctpw.lock);
213	if (kfifo_alloc(&sctpw.fifo, bufsize, GFP_KERNEL))
214		return ret;
215
216	if (!proc_create(procname, S_IRUSR, init_net.proc_net,
217			 &sctpprobe_fops))
218		goto free_kfifo;
219
220	ret = sctp_setup_jprobe();
221	if (ret)
222		goto remove_proc;
223
224	pr_info("probe registered (port=%d/fwmark=%u) bufsize=%u\n",
225		port, fwmark, bufsize);
226	return 0;
227
228remove_proc:
229	remove_proc_entry(procname, init_net.proc_net);
230free_kfifo:
231	kfifo_free(&sctpw.fifo);
232	return ret;
233}
234
235static __exit void sctpprobe_exit(void)
236{
237	kfifo_free(&sctpw.fifo);
238	remove_proc_entry(procname, init_net.proc_net);
239	unregister_jprobe(&sctp_recv_probe);
240}
241
242module_init(sctpprobe_init);
243module_exit(sctpprobe_exit);
244