2 * tcpprobe - Observe the TCP flow with kprobes.
4 * The idea for this came from Werner Almesberger's umlsim
5 * Copyright (C) 2004, Stephen Hemminger <shemminger@osdl.org>
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.
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
21 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
23 #include <linux/kernel.h>
24 #include <linux/kprobes.h>
25 #include <linux/socket.h>
26 #include <linux/tcp.h>
27 #include <linux/slab.h>
28 #include <linux/proc_fs.h>
29 #include <linux/module.h>
30 #include <linux/ktime.h>
31 #include <linux/time.h>
32 #include <net/net_namespace.h>
36 MODULE_AUTHOR("Stephen Hemminger <shemminger@linux-foundation.org>");
37 MODULE_DESCRIPTION("TCP cwnd snooper");
38 MODULE_LICENSE("GPL");
39 MODULE_VERSION("1.1");
41 static int port __read_mostly
;
42 MODULE_PARM_DESC(port
, "Port to match (0=all)");
43 module_param(port
, int, 0);
45 static unsigned int bufsize __read_mostly
= 4096;
46 MODULE_PARM_DESC(bufsize
, "Log buffer size in packets (4096)");
47 module_param(bufsize
, uint
, 0);
49 static unsigned int fwmark __read_mostly
;
50 MODULE_PARM_DESC(fwmark
, "skb mark to match (0=no mark)");
51 module_param(fwmark
, uint
, 0);
53 static int full __read_mostly
;
54 MODULE_PARM_DESC(full
, "Full log (1=every ack packet received, 0=only cwnd changes)");
55 module_param(full
, int, 0);
57 static const char procname
[] = "tcpprobe";
63 struct sockaddr_in v4
;
64 struct sockaddr_in6 v6
;
78 wait_queue_head_t wait
;
82 unsigned long head
, tail
;
87 static inline int tcp_probe_used(void)
89 return (tcp_probe
.head
- tcp_probe
.tail
) & (bufsize
- 1);
92 static inline int tcp_probe_avail(void)
94 return bufsize
- tcp_probe_used() - 1;
97 #define tcp_probe_copy_fl_to_si4(inet, si4, mem) \
99 si4.sin_family = AF_INET; \
100 si4.sin_port = inet->inet_##mem##port; \
101 si4.sin_addr.s_addr = inet->inet_##mem##addr; \
106 * Hook inserted to be called before each receive packet.
107 * Note: arguments must match tcp_rcv_established()!
109 static void jtcp_rcv_established(struct sock
*sk
, struct sk_buff
*skb
,
110 const struct tcphdr
*th
, unsigned int len
)
112 const struct tcp_sock
*tp
= tcp_sk(sk
);
113 const struct inet_sock
*inet
= inet_sk(sk
);
115 /* Only update if port or skb mark matches */
116 if (((port
== 0 && fwmark
== 0) ||
117 ntohs(inet
->inet_dport
) == port
||
118 ntohs(inet
->inet_sport
) == port
||
119 (fwmark
> 0 && skb
->mark
== fwmark
)) &&
120 (full
|| tp
->snd_cwnd
!= tcp_probe
.lastcwnd
)) {
122 spin_lock(&tcp_probe
.lock
);
123 /* If log fills, just silently drop */
124 if (tcp_probe_avail() > 1) {
125 struct tcp_log
*p
= tcp_probe
.log
+ tcp_probe
.head
;
127 p
->tstamp
= ktime_get();
128 switch (sk
->sk_family
) {
130 tcp_probe_copy_fl_to_si4(inet
, p
->src
.v4
, s
);
131 tcp_probe_copy_fl_to_si4(inet
, p
->dst
.v4
, d
);
134 memset(&p
->src
.v6
, 0, sizeof(p
->src
.v6
));
135 memset(&p
->dst
.v6
, 0, sizeof(p
->dst
.v6
));
136 #if IS_ENABLED(CONFIG_IPV6)
137 p
->src
.v6
.sin6_family
= AF_INET6
;
138 p
->src
.v6
.sin6_port
= inet
->inet_sport
;
139 p
->src
.v6
.sin6_addr
= inet6_sk(sk
)->saddr
;
141 p
->dst
.v6
.sin6_family
= AF_INET6
;
142 p
->dst
.v6
.sin6_port
= inet
->inet_dport
;
143 p
->dst
.v6
.sin6_addr
= sk
->sk_v6_daddr
;
150 p
->length
= skb
->len
;
151 p
->snd_nxt
= tp
->snd_nxt
;
152 p
->snd_una
= tp
->snd_una
;
153 p
->snd_cwnd
= tp
->snd_cwnd
;
154 p
->snd_wnd
= tp
->snd_wnd
;
155 p
->rcv_wnd
= tp
->rcv_wnd
;
156 p
->ssthresh
= tcp_current_ssthresh(sk
);
157 p
->srtt
= tp
->srtt
>> 3;
159 tcp_probe
.head
= (tcp_probe
.head
+ 1) & (bufsize
- 1);
161 tcp_probe
.lastcwnd
= tp
->snd_cwnd
;
162 spin_unlock(&tcp_probe
.lock
);
164 wake_up(&tcp_probe
.wait
);
170 static struct jprobe tcp_jprobe
= {
172 .symbol_name
= "tcp_rcv_established",
174 .entry
= jtcp_rcv_established
,
177 static int tcpprobe_open(struct inode
*inode
, struct file
*file
)
179 /* Reset (empty) log */
180 spin_lock_bh(&tcp_probe
.lock
);
181 tcp_probe
.head
= tcp_probe
.tail
= 0;
182 tcp_probe
.start
= ktime_get();
183 spin_unlock_bh(&tcp_probe
.lock
);
188 static int tcpprobe_sprint(char *tbuf
, int n
)
190 const struct tcp_log
*p
191 = tcp_probe
.log
+ tcp_probe
.tail
;
193 = ktime_to_timespec(ktime_sub(p
->tstamp
, tcp_probe
.start
));
195 return scnprintf(tbuf
, n
,
196 "%lu.%09lu %pISpc %pISpc %d %#x %#x %u %u %u %u %u\n",
197 (unsigned long) tv
.tv_sec
,
198 (unsigned long) tv
.tv_nsec
,
199 &p
->src
, &p
->dst
, p
->length
, p
->snd_nxt
, p
->snd_una
,
200 p
->snd_cwnd
, p
->ssthresh
, p
->snd_wnd
, p
->srtt
, p
->rcv_wnd
);
203 static ssize_t
tcpprobe_read(struct file
*file
, char __user
*buf
,
204 size_t len
, loff_t
*ppos
)
216 /* Wait for data in buffer */
217 error
= wait_event_interruptible(tcp_probe
.wait
,
218 tcp_probe_used() > 0);
222 spin_lock_bh(&tcp_probe
.lock
);
223 if (tcp_probe
.head
== tcp_probe
.tail
) {
224 /* multiple readers race? */
225 spin_unlock_bh(&tcp_probe
.lock
);
229 width
= tcpprobe_sprint(tbuf
, sizeof(tbuf
));
231 if (cnt
+ width
< len
)
232 tcp_probe
.tail
= (tcp_probe
.tail
+ 1) & (bufsize
- 1);
234 spin_unlock_bh(&tcp_probe
.lock
);
236 /* if record greater than space available
237 return partial buffer (so far) */
238 if (cnt
+ width
>= len
)
241 if (copy_to_user(buf
+ cnt
, tbuf
, width
))
246 return cnt
== 0 ? error
: cnt
;
249 static const struct file_operations tcpprobe_fops
= {
250 .owner
= THIS_MODULE
,
251 .open
= tcpprobe_open
,
252 .read
= tcpprobe_read
,
253 .llseek
= noop_llseek
,
256 static __init
int tcpprobe_init(void)
260 /* Warning: if the function signature of tcp_rcv_established,
261 * has been changed, you also have to change the signature of
262 * jtcp_rcv_established, otherwise you end up right here!
264 BUILD_BUG_ON(__same_type(tcp_rcv_established
,
265 jtcp_rcv_established
) == 0);
267 init_waitqueue_head(&tcp_probe
.wait
);
268 spin_lock_init(&tcp_probe
.lock
);
273 bufsize
= roundup_pow_of_two(bufsize
);
274 tcp_probe
.log
= kcalloc(bufsize
, sizeof(struct tcp_log
), GFP_KERNEL
);
278 if (!proc_create(procname
, S_IRUSR
, init_net
.proc_net
, &tcpprobe_fops
))
281 ret
= register_jprobe(&tcp_jprobe
);
285 pr_info("probe registered (port=%d/fwmark=%u) bufsize=%u\n",
286 port
, fwmark
, bufsize
);
289 remove_proc_entry(procname
, init_net
.proc_net
);
291 kfree(tcp_probe
.log
);
294 module_init(tcpprobe_init
);
296 static __exit
void tcpprobe_exit(void)
298 remove_proc_entry(procname
, init_net
.proc_net
);
299 unregister_jprobe(&tcp_jprobe
);
300 kfree(tcp_probe
.log
);
302 module_exit(tcpprobe_exit
);