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
41 MODULE_AUTHOR("Wei Yongjun <yjwei@cn.fujitsu.com>");
42 MODULE_DESCRIPTION("SCTP snooper");
43 MODULE_LICENSE("GPL");
44
45 static int port __read_mostly = 0;
46 MODULE_PARM_DESC(port, "Port to match (0=all)");
47 module_param(port, int, 0);
48
49 static int bufsize __read_mostly = 64 * 1024;
50 MODULE_PARM_DESC(bufsize, "Log buffer size (default 64k)");
51 module_param(bufsize, int, 0);
52
53 static int full __read_mostly = 1;
54 MODULE_PARM_DESC(full, "Full log (1=every ack packet received, 0=only cwnd changes)");
55 module_param(full, int, 0);
56
57 static const char procname[] = "sctpprobe";
58
59 static struct {
60 struct kfifo fifo;
61 spinlock_t lock;
62 wait_queue_head_t wait;
63 struct timespec tstart;
64 } sctpw;
65
printl(const char * fmt,...)66 static __printf(1, 2) void printl(const char *fmt, ...)
67 {
68 va_list args;
69 int len;
70 char tbuf[256];
71
72 va_start(args, fmt);
73 len = vscnprintf(tbuf, sizeof(tbuf), fmt, args);
74 va_end(args);
75
76 kfifo_in_locked(&sctpw.fifo, tbuf, len, &sctpw.lock);
77 wake_up(&sctpw.wait);
78 }
79
sctpprobe_open(struct inode * inode,struct file * file)80 static int sctpprobe_open(struct inode *inode, struct file *file)
81 {
82 kfifo_reset(&sctpw.fifo);
83 getnstimeofday(&sctpw.tstart);
84
85 return 0;
86 }
87
sctpprobe_read(struct file * file,char __user * buf,size_t len,loff_t * ppos)88 static ssize_t sctpprobe_read(struct file *file, char __user *buf,
89 size_t len, loff_t *ppos)
90 {
91 int error = 0, cnt = 0;
92 unsigned char *tbuf;
93
94 if (!buf)
95 return -EINVAL;
96
97 if (len == 0)
98 return 0;
99
100 tbuf = vmalloc(len);
101 if (!tbuf)
102 return -ENOMEM;
103
104 error = wait_event_interruptible(sctpw.wait,
105 kfifo_len(&sctpw.fifo) != 0);
106 if (error)
107 goto out_free;
108
109 cnt = kfifo_out_locked(&sctpw.fifo, tbuf, len, &sctpw.lock);
110 error = copy_to_user(buf, tbuf, cnt) ? -EFAULT : 0;
111
112 out_free:
113 vfree(tbuf);
114
115 return error ? error : cnt;
116 }
117
118 static const struct file_operations sctpprobe_fops = {
119 .owner = THIS_MODULE,
120 .open = sctpprobe_open,
121 .read = sctpprobe_read,
122 .llseek = noop_llseek,
123 };
124
jsctp_sf_eat_sack(struct net * net,const struct sctp_endpoint * ep,const struct sctp_association * asoc,const sctp_subtype_t type,void * arg,sctp_cmd_seq_t * commands)125 static sctp_disposition_t jsctp_sf_eat_sack(struct net *net,
126 const struct sctp_endpoint *ep,
127 const struct sctp_association *asoc,
128 const sctp_subtype_t type,
129 void *arg,
130 sctp_cmd_seq_t *commands)
131 {
132 struct sctp_transport *sp;
133 static __u32 lcwnd = 0;
134 struct timespec now;
135
136 sp = asoc->peer.primary_path;
137
138 if ((full || sp->cwnd != lcwnd) &&
139 (!port || asoc->peer.port == port ||
140 ep->base.bind_addr.port == port)) {
141 lcwnd = sp->cwnd;
142
143 getnstimeofday(&now);
144 now = timespec_sub(now, sctpw.tstart);
145
146 printl("%lu.%06lu ", (unsigned long) now.tv_sec,
147 (unsigned long) now.tv_nsec / NSEC_PER_USEC);
148
149 printl("%p %5d %5d %5d %8d %5d ", asoc,
150 ep->base.bind_addr.port, asoc->peer.port,
151 asoc->pathmtu, asoc->peer.rwnd, asoc->unack_data);
152
153 list_for_each_entry(sp, &asoc->peer.transport_addr_list,
154 transports) {
155 if (sp == asoc->peer.primary_path)
156 printl("*");
157
158 if (sp->ipaddr.sa.sa_family == AF_INET)
159 printl("%pI4 ", &sp->ipaddr.v4.sin_addr);
160 else
161 printl("%pI6 ", &sp->ipaddr.v6.sin6_addr);
162
163 printl("%2u %8u %8u %8u %8u %8u ",
164 sp->state, sp->cwnd, sp->ssthresh,
165 sp->flight_size, sp->partial_bytes_acked,
166 sp->pathmtu);
167 }
168 printl("\n");
169 }
170
171 jprobe_return();
172 return 0;
173 }
174
175 static struct jprobe sctp_recv_probe = {
176 .kp = {
177 .symbol_name = "sctp_sf_eat_sack_6_2",
178 },
179 .entry = jsctp_sf_eat_sack,
180 };
181
sctpprobe_init(void)182 static __init int sctpprobe_init(void)
183 {
184 int ret = -ENOMEM;
185
186 /* Warning: if the function signature of sctp_sf_eat_sack_6_2,
187 * has been changed, you also have to change the signature of
188 * jsctp_sf_eat_sack, otherwise you end up right here!
189 */
190 BUILD_BUG_ON(__same_type(sctp_sf_eat_sack_6_2,
191 jsctp_sf_eat_sack) == 0);
192
193 init_waitqueue_head(&sctpw.wait);
194 spin_lock_init(&sctpw.lock);
195 if (kfifo_alloc(&sctpw.fifo, bufsize, GFP_KERNEL))
196 return ret;
197
198 if (!proc_create(procname, S_IRUSR, init_net.proc_net,
199 &sctpprobe_fops))
200 goto free_kfifo;
201
202 ret = register_jprobe(&sctp_recv_probe);
203 if (ret)
204 goto remove_proc;
205
206 pr_info("probe registered (port=%d)\n", port);
207
208 return 0;
209
210 remove_proc:
211 remove_proc_entry(procname, init_net.proc_net);
212 free_kfifo:
213 kfifo_free(&sctpw.fifo);
214 return ret;
215 }
216
sctpprobe_exit(void)217 static __exit void sctpprobe_exit(void)
218 {
219 kfifo_free(&sctpw.fifo);
220 remove_proc_entry(procname, init_net.proc_net);
221 unregister_jprobe(&sctp_recv_probe);
222 }
223
224 module_init(sctpprobe_init);
225 module_exit(sctpprobe_exit);
226