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21#include <linux/kernel.h>
22#include <linux/kprobes.h>
23#include <linux/socket.h>
24#include <linux/tcp.h>
25#include <linux/slab.h>
26#include <linux/proc_fs.h>
27#include <linux/module.h>
28#include <linux/ktime.h>
29#include <linux/time.h>
30#include <net/net_namespace.h>
31
32#include <net/tcp.h>
33
34MODULE_AUTHOR("Stephen Hemminger <shemminger@linux-foundation.org>");
35MODULE_DESCRIPTION("TCP cwnd snooper");
36MODULE_LICENSE("GPL");
37MODULE_VERSION("1.1");
38
39static int port __read_mostly = 0;
40MODULE_PARM_DESC(port, "Port to match (0=all)");
41module_param(port, int, 0);
42
43static unsigned int bufsize __read_mostly = 4096;
44MODULE_PARM_DESC(bufsize, "Log buffer size in packets (4096)");
45module_param(bufsize, uint, 0);
46
47static int full __read_mostly;
48MODULE_PARM_DESC(full, "Full log (1=every ack packet received, 0=only cwnd changes)");
49module_param(full, int, 0);
50
51static const char procname[] = "tcpprobe";
52
53struct 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
66static struct {
67 spinlock_t lock;
68 wait_queue_head_t wait;
69 ktime_t start;
70 u32 lastcwnd;
71
72 unsigned long head, tail;
73 struct tcp_log *log;
74} tcp_probe;
75
76
77static inline int tcp_probe_used(void)
78{
79 return (tcp_probe.head - tcp_probe.tail) & (bufsize - 1);
80}
81
82static inline int tcp_probe_avail(void)
83{
84 return bufsize - tcp_probe_used() - 1;
85}
86
87
88
89
90
91static int jtcp_rcv_established(struct sock *sk, struct sk_buff *skb,
92 struct tcphdr *th, unsigned len)
93{
94 const struct tcp_sock *tp = tcp_sk(sk);
95 const struct inet_sock *inet = inet_sk(sk);
96
97
98 if ((port == 0 || ntohs(inet->inet_dport) == port ||
99 ntohs(inet->inet_sport) == port) &&
100 (full || tp->snd_cwnd != tcp_probe.lastcwnd)) {
101
102 spin_lock(&tcp_probe.lock);
103
104 if (tcp_probe_avail() > 1) {
105 struct tcp_log *p = tcp_probe.log + tcp_probe.head;
106
107 p->tstamp = ktime_get();
108 p->saddr = inet->inet_saddr;
109 p->sport = inet->inet_sport;
110 p->daddr = inet->inet_daddr;
111 p->dport = inet->inet_dport;
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;
117 p->ssthresh = tcp_current_ssthresh(sk);
118 p->srtt = tp->srtt >> 3;
119
120 tcp_probe.head = (tcp_probe.head + 1) & (bufsize - 1);
121 }
122 tcp_probe.lastcwnd = tp->snd_cwnd;
123 spin_unlock(&tcp_probe.lock);
124
125 wake_up(&tcp_probe.wait);
126 }
127
128 jprobe_return();
129 return 0;
130}
131
132static struct jprobe tcp_jprobe = {
133 .kp = {
134 .symbol_name = "tcp_rcv_established",
135 },
136 .entry = jtcp_rcv_established,
137};
138
139static int tcpprobe_open(struct inode * inode, struct file * file)
140{
141
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
147 return 0;
148}
149
150static int tcpprobe_sprint(char *tbuf, int n)
151{
152 const struct tcp_log *p
153 = tcp_probe.log + tcp_probe.tail;
154 struct timespec tv
155 = ktime_to_timespec(ktime_sub(p->tstamp, tcp_probe.start));
156
157 return scnprintf(tbuf, n,
158 "%lu.%09lu %pI4:%u %pI4:%u %d %#x %#x %u %u %u %u\n",
159 (unsigned long) tv.tv_sec,
160 (unsigned long) tv.tv_nsec,
161 &p->saddr, ntohs(p->sport),
162 &p->daddr, ntohs(p->dport),
163 p->length, p->snd_nxt, p->snd_una,
164 p->snd_cwnd, p->ssthresh, p->snd_wnd, p->srtt);
165}
166
167static ssize_t tcpprobe_read(struct file *file, char __user *buf,
168 size_t len, loff_t *ppos)
169{
170 int error = 0;
171 size_t cnt = 0;
172
173 if (!buf)
174 return -EINVAL;
175
176 while (cnt < len) {
177 char tbuf[164];
178 int width;
179
180
181 error = wait_event_interruptible(tcp_probe.wait,
182 tcp_probe_used() > 0);
183 if (error)
184 break;
185
186 spin_lock_bh(&tcp_probe.lock);
187 if (tcp_probe.head == tcp_probe.tail) {
188
189 spin_unlock_bh(&tcp_probe.lock);
190 continue;
191 }
192
193 width = tcpprobe_sprint(tbuf, sizeof(tbuf));
194
195 if (cnt + width < len)
196 tcp_probe.tail = (tcp_probe.tail + 1) & (bufsize - 1);
197
198 spin_unlock_bh(&tcp_probe.lock);
199
200
201
202 if (cnt + width >= len)
203 break;
204
205 if (copy_to_user(buf + cnt, tbuf, width))
206 return -EFAULT;
207 cnt += width;
208 }
209
210 return cnt == 0 ? error : cnt;
211}
212
213static const struct file_operations tcpprobe_fops = {
214 .owner = THIS_MODULE,
215 .open = tcpprobe_open,
216 .read = tcpprobe_read,
217 .llseek = noop_llseek,
218};
219
220static __init int tcpprobe_init(void)
221{
222 int ret = -ENOMEM;
223
224 init_waitqueue_head(&tcp_probe.wait);
225 spin_lock_init(&tcp_probe.lock);
226
227 if (bufsize == 0)
228 return -EINVAL;
229
230 bufsize = roundup_pow_of_two(bufsize);
231 tcp_probe.log = kcalloc(bufsize, sizeof(struct tcp_log), GFP_KERNEL);
232 if (!tcp_probe.log)
233 goto err0;
234
235 if (!proc_net_fops_create(&init_net, procname, S_IRUSR, &tcpprobe_fops))
236 goto err0;
237
238 ret = register_jprobe(&tcp_jprobe);
239 if (ret)
240 goto err1;
241
242 pr_info("TCP probe registered (port=%d) bufsize=%u\n", port, bufsize);
243 return 0;
244 err1:
245 proc_net_remove(&init_net, procname);
246 err0:
247 kfree(tcp_probe.log);
248 return ret;
249}
250module_init(tcpprobe_init);
251
252static __exit void tcpprobe_exit(void)
253{
254 proc_net_remove(&init_net, procname);
255 unregister_jprobe(&tcp_jprobe);
256 kfree(tcp_probe.log);
257}
258module_exit(tcpprobe_exit);
259
