Commit | Line | Data |
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a42e9d6c SH |
1 | /* |
2 | * tcpprobe - Observe the TCP 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 | * 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 | |
662ad4f8 | 9 | * the Free Software Foundation; either version 2 of the License. |
a42e9d6c SH |
10 | * |
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. | |
15 | * | |
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. | |
19 | */ | |
20 | ||
21 | #include <linux/kernel.h> | |
22 | #include <linux/kprobes.h> | |
23 | #include <linux/socket.h> | |
24 | #include <linux/tcp.h> | |
5a0e3ad6 | 25 | #include <linux/slab.h> |
a42e9d6c SH |
26 | #include <linux/proc_fs.h> |
27 | #include <linux/module.h> | |
85795d64 SH |
28 | #include <linux/ktime.h> |
29 | #include <linux/time.h> | |
457c4cbc | 30 | #include <net/net_namespace.h> |
a42e9d6c SH |
31 | |
32 | #include <net/tcp.h> | |
33 | ||
65ebe634 | 34 | MODULE_AUTHOR("Stephen Hemminger <shemminger@linux-foundation.org>"); |
a42e9d6c SH |
35 | MODULE_DESCRIPTION("TCP cwnd snooper"); |
36 | MODULE_LICENSE("GPL"); | |
662ad4f8 | 37 | MODULE_VERSION("1.1"); |
a42e9d6c | 38 | |
85795d64 | 39 | static int port __read_mostly = 0; |
a42e9d6c SH |
40 | MODULE_PARM_DESC(port, "Port to match (0=all)"); |
41 | module_param(port, int, 0); | |
42 | ||
f81074f8 | 43 | static unsigned int bufsize __read_mostly = 4096; |
662ad4f8 | 44 | MODULE_PARM_DESC(bufsize, "Log buffer size in packets (4096)"); |
f81074f8 | 45 | module_param(bufsize, uint, 0); |
a42e9d6c | 46 | |
85795d64 SH |
47 | static int full __read_mostly; |
48 | MODULE_PARM_DESC(full, "Full log (1=every ack packet received, 0=only cwnd changes)"); | |
49 | module_param(full, int, 0); | |
50 | ||
a42e9d6c SH |
51 | static const char procname[] = "tcpprobe"; |
52 | ||
662ad4f8 SH |
53 | struct tcp_log { |
54 | ktime_t tstamp; | |
55 | __be32 saddr, daddr; | |
56 | __be16 sport, dport; | |
57 | u16 length; | |
58 | u32 snd_nxt; | |
59 | u32 snd_una; | |
60 | u32 snd_wnd; | |
61 | u32 snd_cwnd; | |
62 | u32 ssthresh; | |
63 | u32 srtt; | |
64 | }; | |
65 | ||
66 | static struct { | |
85795d64 | 67 | spinlock_t lock; |
a42e9d6c | 68 | wait_queue_head_t wait; |
85795d64 SH |
69 | ktime_t start; |
70 | u32 lastcwnd; | |
a42e9d6c | 71 | |
662ad4f8 SH |
72 | unsigned long head, tail; |
73 | struct tcp_log *log; | |
74 | } tcp_probe; | |
75 | ||
14a49e1f | 76 | |
662ad4f8 | 77 | static inline int tcp_probe_used(void) |
a42e9d6c | 78 | { |
f81074f8 | 79 | return (tcp_probe.head - tcp_probe.tail) & (bufsize - 1); |
662ad4f8 SH |
80 | } |
81 | ||
82 | static inline int tcp_probe_avail(void) | |
83 | { | |
f81074f8 | 84 | return bufsize - tcp_probe_used() - 1; |
14a49e1f | 85 | } |
a42e9d6c | 86 | |
85795d64 SH |
87 | /* |
88 | * Hook inserted to be called before each receive packet. | |
89 | * Note: arguments must match tcp_rcv_established()! | |
90 | */ | |
91 | static int jtcp_rcv_established(struct sock *sk, struct sk_buff *skb, | |
92 | struct tcphdr *th, unsigned len) | |
a42e9d6c SH |
93 | { |
94 | const struct tcp_sock *tp = tcp_sk(sk); | |
95 | const struct inet_sock *inet = inet_sk(sk); | |
96 | ||
85795d64 | 97 | /* Only update if port matches */ |
c720c7e8 | 98 | if ((port == 0 || ntohs(inet->inet_dport) == port || |
9d4fb27d JP |
99 | ntohs(inet->inet_sport) == port) && |
100 | (full || tp->snd_cwnd != tcp_probe.lastcwnd)) { | |
662ad4f8 SH |
101 | |
102 | spin_lock(&tcp_probe.lock); | |
103 | /* If log fills, just silently drop */ | |
104 | if (tcp_probe_avail() > 1) { | |
105 | struct tcp_log *p = tcp_probe.log + tcp_probe.head; | |
106 | ||
107 | p->tstamp = ktime_get(); | |
c720c7e8 ED |
108 | p->saddr = inet->inet_saddr; |
109 | p->sport = inet->inet_sport; | |
110 | p->daddr = inet->inet_daddr; | |
111 | p->dport = inet->inet_dport; | |
662ad4f8 SH |
112 | p->length = skb->len; |
113 | p->snd_nxt = tp->snd_nxt; | |
114 | p->snd_una = tp->snd_una; | |
115 | p->snd_cwnd = tp->snd_cwnd; | |
116 | p->snd_wnd = tp->snd_wnd; | |
b3b0b681 | 117 | p->ssthresh = tcp_current_ssthresh(sk); |
662ad4f8 SH |
118 | p->srtt = tp->srtt >> 3; |
119 | ||
f81074f8 | 120 | tcp_probe.head = (tcp_probe.head + 1) & (bufsize - 1); |
662ad4f8 SH |
121 | } |
122 | tcp_probe.lastcwnd = tp->snd_cwnd; | |
123 | spin_unlock(&tcp_probe.lock); | |
124 | ||
125 | wake_up(&tcp_probe.wait); | |
a42e9d6c SH |
126 | } |
127 | ||
128 | jprobe_return(); | |
129 | return 0; | |
130 | } | |
131 | ||
662ad4f8 | 132 | static struct jprobe tcp_jprobe = { |
3a872d89 | 133 | .kp = { |
85795d64 | 134 | .symbol_name = "tcp_rcv_established", |
3a872d89 | 135 | }, |
9e367d85 | 136 | .entry = jtcp_rcv_established, |
a42e9d6c SH |
137 | }; |
138 | ||
a42e9d6c SH |
139 | static int tcpprobe_open(struct inode * inode, struct file * file) |
140 | { | |
662ad4f8 SH |
141 | /* Reset (empty) log */ |
142 | spin_lock_bh(&tcp_probe.lock); | |
143 | tcp_probe.head = tcp_probe.tail = 0; | |
144 | tcp_probe.start = ktime_get(); | |
145 | spin_unlock_bh(&tcp_probe.lock); | |
146 | ||
a42e9d6c SH |
147 | return 0; |
148 | } | |
149 | ||
662ad4f8 SH |
150 | static int tcpprobe_sprint(char *tbuf, int n) |
151 | { | |
152 | const struct tcp_log *p | |
f81074f8 | 153 | = tcp_probe.log + tcp_probe.tail; |
662ad4f8 SH |
154 | struct timespec tv |
155 | = ktime_to_timespec(ktime_sub(p->tstamp, tcp_probe.start)); | |
156 | ||
157 | return snprintf(tbuf, n, | |
673d57e7 | 158 | "%lu.%09lu %pI4:%u %pI4:%u %d %#x %#x %u %u %u %u\n", |
662ad4f8 SH |
159 | (unsigned long) tv.tv_sec, |
160 | (unsigned long) tv.tv_nsec, | |
673d57e7 HH |
161 | &p->saddr, ntohs(p->sport), |
162 | &p->daddr, ntohs(p->dport), | |
662ad4f8 SH |
163 | p->length, p->snd_nxt, p->snd_una, |
164 | p->snd_cwnd, p->ssthresh, p->snd_wnd, p->srtt); | |
165 | } | |
166 | ||
a42e9d6c SH |
167 | static ssize_t tcpprobe_read(struct file *file, char __user *buf, |
168 | size_t len, loff_t *ppos) | |
169 | { | |
a2025b8b RK |
170 | int error = 0; |
171 | size_t cnt = 0; | |
a42e9d6c | 172 | |
a2025b8b | 173 | if (!buf) |
a42e9d6c SH |
174 | return -EINVAL; |
175 | ||
662ad4f8 SH |
176 | while (cnt < len) { |
177 | char tbuf[128]; | |
178 | int width; | |
179 | ||
180 | /* Wait for data in buffer */ | |
181 | error = wait_event_interruptible(tcp_probe.wait, | |
182 | tcp_probe_used() > 0); | |
183 | if (error) | |
184 | break; | |
a42e9d6c | 185 | |
662ad4f8 SH |
186 | spin_lock_bh(&tcp_probe.lock); |
187 | if (tcp_probe.head == tcp_probe.tail) { | |
188 | /* multiple readers race? */ | |
189 | spin_unlock_bh(&tcp_probe.lock); | |
190 | continue; | |
191 | } | |
a42e9d6c | 192 | |
662ad4f8 | 193 | width = tcpprobe_sprint(tbuf, sizeof(tbuf)); |
a42e9d6c | 194 | |
8d390efd | 195 | if (cnt + width < len) |
f81074f8 | 196 | tcp_probe.tail = (tcp_probe.tail + 1) & (bufsize - 1); |
a42e9d6c | 197 | |
662ad4f8 SH |
198 | spin_unlock_bh(&tcp_probe.lock); |
199 | ||
200 | /* if record greater than space available | |
201 | return partial buffer (so far) */ | |
8d390efd | 202 | if (cnt + width >= len) |
662ad4f8 SH |
203 | break; |
204 | ||
8d390efd TQ |
205 | if (copy_to_user(buf + cnt, tbuf, width)) |
206 | return -EFAULT; | |
662ad4f8 SH |
207 | cnt += width; |
208 | } | |
a42e9d6c | 209 | |
662ad4f8 | 210 | return cnt == 0 ? error : cnt; |
a42e9d6c SH |
211 | } |
212 | ||
9a32144e | 213 | static const struct file_operations tcpprobe_fops = { |
a42e9d6c SH |
214 | .owner = THIS_MODULE, |
215 | .open = tcpprobe_open, | |
216 | .read = tcpprobe_read, | |
217 | }; | |
218 | ||
219 | static __init int tcpprobe_init(void) | |
220 | { | |
221 | int ret = -ENOMEM; | |
222 | ||
662ad4f8 SH |
223 | init_waitqueue_head(&tcp_probe.wait); |
224 | spin_lock_init(&tcp_probe.lock); | |
225 | ||
f81074f8 | 226 | if (bufsize == 0) |
662ad4f8 SH |
227 | return -EINVAL; |
228 | ||
f81074f8 | 229 | bufsize = roundup_pow_of_two(bufsize); |
3d8ea1fd | 230 | tcp_probe.log = kcalloc(bufsize, sizeof(struct tcp_log), GFP_KERNEL); |
662ad4f8 SH |
231 | if (!tcp_probe.log) |
232 | goto err0; | |
a42e9d6c | 233 | |
457c4cbc | 234 | if (!proc_net_fops_create(&init_net, procname, S_IRUSR, &tcpprobe_fops)) |
a42e9d6c SH |
235 | goto err0; |
236 | ||
662ad4f8 | 237 | ret = register_jprobe(&tcp_jprobe); |
a42e9d6c SH |
238 | if (ret) |
239 | goto err1; | |
240 | ||
f81074f8 | 241 | pr_info("TCP probe registered (port=%d) bufsize=%u\n", port, bufsize); |
a42e9d6c SH |
242 | return 0; |
243 | err1: | |
457c4cbc | 244 | proc_net_remove(&init_net, procname); |
a42e9d6c | 245 | err0: |
662ad4f8 | 246 | kfree(tcp_probe.log); |
a42e9d6c SH |
247 | return ret; |
248 | } | |
249 | module_init(tcpprobe_init); | |
250 | ||
251 | static __exit void tcpprobe_exit(void) | |
252 | { | |
457c4cbc | 253 | proc_net_remove(&init_net, procname); |
662ad4f8 SH |
254 | unregister_jprobe(&tcp_jprobe); |
255 | kfree(tcp_probe.log); | |
a42e9d6c SH |
256 | } |
257 | module_exit(tcpprobe_exit); |