[GitHub/MotorolaMobilityLLC/kernel-slsi.git] / net / ipv4 / tcp_probe.c

/*
 * tcpprobe - Observe the TCP flow with kprobes.
 *
 * The idea for this came from Werner Almesberger's umlsim
 * Copyright (C) 2004, Stephen Hemminger <shemminger@osdl.org>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <linux/kernel.h>
#include <linux/kprobes.h>
#include <linux/socket.h>
#include <linux/tcp.h>
#include <linux/proc_fs.h>
#include <linux/module.h>
#include <linux/ktime.h>
#include <linux/time.h>

#include <net/tcp.h>

MODULE_AUTHOR("Stephen Hemminger <shemminger@linux-foundation.org>");
MODULE_DESCRIPTION("TCP cwnd snooper");
MODULE_LICENSE("GPL");
MODULE_VERSION("1.1");

static int port __read_mostly = 0;
MODULE_PARM_DESC(port, "Port to match (0=all)");
module_param(port, int, 0);

static int bufsize __read_mostly = 4096;
MODULE_PARM_DESC(bufsize, "Log buffer size in packets (4096)");
module_param(bufsize, int, 0);

static int full __read_mostly;
MODULE_PARM_DESC(full, "Full log (1=every ack packet received,  0=only cwnd changes)");
module_param(full, int, 0);

static const char procname[] = "tcpprobe";

struct tcp_log {
	ktime_t tstamp;
	__be32	saddr, daddr;
	__be16	sport, dport;
	u16	length;
	u32	snd_nxt;
	u32	snd_una;
	u32	snd_wnd;
	u32	snd_cwnd;
	u32	ssthresh;
	u32	srtt;
};

static struct {
	spinlock_t	lock;
	wait_queue_head_t wait;
	ktime_t		start;
	u32		lastcwnd;

	unsigned long	head, tail;
	struct tcp_log	*log;
} tcp_probe;


static inline int tcp_probe_used(void)
{
	return (tcp_probe.head - tcp_probe.tail) % bufsize;
}

static inline int tcp_probe_avail(void)
{
	return bufsize - tcp_probe_used();
}

/*
 * Hook inserted to be called before each receive packet.
 * Note: arguments must match tcp_rcv_established()!
 */
static int jtcp_rcv_established(struct sock *sk, struct sk_buff *skb,
			       struct tcphdr *th, unsigned len)
{
	const struct tcp_sock *tp = tcp_sk(sk);
	const struct inet_sock *inet = inet_sk(sk);

	/* Only update if port matches */
	if ((port == 0 || ntohs(inet->dport) == port || ntohs(inet->sport) == port)
	    && (full || tp->snd_cwnd != tcp_probe.lastcwnd)) {

		spin_lock(&tcp_probe.lock);
		/* If log fills, just silently drop */
		if (tcp_probe_avail() > 1) {
			struct tcp_log *p = tcp_probe.log + tcp_probe.head;

			p->tstamp = ktime_get();
			p->saddr = inet->saddr;
			p->sport = inet->sport;
			p->daddr = inet->daddr;
			p->dport = inet->dport;
			p->length = skb->len;
			p->snd_nxt = tp->snd_nxt;
			p->snd_una = tp->snd_una;
			p->snd_cwnd = tp->snd_cwnd;
			p->snd_wnd = tp->snd_wnd;
			p->ssthresh = tcp_current_ssthresh(sk);
			p->srtt = tp->srtt >> 3;

			tcp_probe.head = (tcp_probe.head + 1) % bufsize;
		}
		tcp_probe.lastcwnd = tp->snd_cwnd;
		spin_unlock(&tcp_probe.lock);

		wake_up(&tcp_probe.wait);
	}

	jprobe_return();
	return 0;
}

static struct jprobe tcp_jprobe = {
	.kp = {
		.symbol_name	= "tcp_rcv_established",
	},
	.entry	= jtcp_rcv_established,
};

static int tcpprobe_open(struct inode * inode, struct file * file)
{
	/* Reset (empty) log */
	spin_lock_bh(&tcp_probe.lock);
	tcp_probe.head = tcp_probe.tail = 0;
	tcp_probe.start = ktime_get();
	spin_unlock_bh(&tcp_probe.lock);

	return 0;
}

static int tcpprobe_sprint(char *tbuf, int n)
{
	const struct tcp_log *p
		= tcp_probe.log + tcp_probe.tail % bufsize;
	struct timespec tv
		= ktime_to_timespec(ktime_sub(p->tstamp, tcp_probe.start));

	return snprintf(tbuf, n,
			"%lu.%09lu %d.%d.%d.%d:%u %d.%d.%d.%d:%u"
			" %d %#x %#x %u %u %u %u\n",
			(unsigned long) tv.tv_sec,
			(unsigned long) tv.tv_nsec,
			NIPQUAD(p->saddr), ntohs(p->sport),
			NIPQUAD(p->daddr), ntohs(p->dport),
			p->length, p->snd_nxt, p->snd_una,
			p->snd_cwnd, p->ssthresh, p->snd_wnd, p->srtt);
}

static ssize_t tcpprobe_read(struct file *file, char __user *buf,
			     size_t len, loff_t *ppos)
{
	int error = 0, cnt = 0;

	if (!buf || len < 0)
		return -EINVAL;

	while (cnt < len) {
		char tbuf[128];
		int width;

		/* Wait for data in buffer */
		error = wait_event_interruptible(tcp_probe.wait,
						 tcp_probe_used() > 0);
		if (error)
			break;

		spin_lock_bh(&tcp_probe.lock);
		if (tcp_probe.head == tcp_probe.tail) {
			/* multiple readers race? */
			spin_unlock_bh(&tcp_probe.lock);
			continue;
		}

		width = tcpprobe_sprint(tbuf, sizeof(tbuf));

		if (width < len)
			tcp_probe.tail = (tcp_probe.tail + 1) % bufsize;

		spin_unlock_bh(&tcp_probe.lock);

		/* if record greater than space available
		   return partial buffer (so far) */
		if (width >= len)
			break;

		error = copy_to_user(buf + cnt, tbuf, width);
		if (error)
			break;
		cnt += width;
	}

	return cnt == 0 ? error : cnt;
}

static const struct file_operations tcpprobe_fops = {
	.owner	 = THIS_MODULE,
	.open	 = tcpprobe_open,
	.read    = tcpprobe_read,
};

static __init int tcpprobe_init(void)
{
	int ret = -ENOMEM;

	init_waitqueue_head(&tcp_probe.wait);
	spin_lock_init(&tcp_probe.lock);

	if (bufsize < 0)
		return -EINVAL;

	tcp_probe.log = kcalloc(sizeof(struct tcp_log), bufsize, GFP_KERNEL);
	if (!tcp_probe.log)
		goto err0;

	if (!proc_net_fops_create(procname, S_IRUSR, &tcpprobe_fops))
		goto err0;

	ret = register_jprobe(&tcp_jprobe);
	if (ret)
		goto err1;

	pr_info("TCP probe registered (port=%d)\n", port);
	return 0;
 err1:
	proc_net_remove(procname);
 err0:
	kfree(tcp_probe.log);
	return ret;
}
module_init(tcpprobe_init);

static __exit void tcpprobe_exit(void)
{
	proc_net_remove(procname);
	unregister_jprobe(&tcp_jprobe);
	kfree(tcp_probe.log);
}
module_exit(tcpprobe_exit);
Commit	Line	Data
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>
	25	#include <linux/proc_fs.h>
	26	#include <linux/module.h>
85795d64 SH	27	#include <linux/ktime.h>
85795d64 SH	28	#include <linux/time.h>
a42e9d6c SH	29
	30	#include <net/tcp.h>
	31
65ebe634	32	MODULE_AUTHOR("Stephen Hemminger <shemminger@linux-foundation.org>");
a42e9d6c SH	33	MODULE_DESCRIPTION("TCP cwnd snooper");
a42e9d6c SH	34	MODULE_LICENSE("GPL");
662ad4f8	35	MODULE_VERSION("1.1");
a42e9d6c	36
85795d64	37	static int port __read_mostly = 0;
a42e9d6c SH	38	MODULE_PARM_DESC(port, "Port to match (0=all)");
	39	module_param(port, int, 0);
	40
662ad4f8 SH	41	static int bufsize __read_mostly = 4096;
662ad4f8 SH	42	MODULE_PARM_DESC(bufsize, "Log buffer size in packets (4096)");
a42e9d6c SH	43	module_param(bufsize, int, 0);
a42e9d6c SH	44
85795d64 SH	45	static int full __read_mostly;
	46	MODULE_PARM_DESC(full, "Full log (1=every ack packet received, 0=only cwnd changes)");
	47	module_param(full, int, 0);
	48
a42e9d6c SH	49	static const char procname[] = "tcpprobe";
a42e9d6c SH	50
662ad4f8 SH	51	struct tcp_log {
	52	ktime_t tstamp;
	53	__be32 saddr, daddr;
	54	__be16 sport, dport;
	55	u16 length;
	56	u32 snd_nxt;
	57	u32 snd_una;
	58	u32 snd_wnd;
	59	u32 snd_cwnd;
	60	u32 ssthresh;
	61	u32 srtt;
	62	};
	63
	64	static struct {
85795d64	65	spinlock_t lock;
a42e9d6c	66	wait_queue_head_t wait;
85795d64 SH	67	ktime_t start;
85795d64 SH	68	u32 lastcwnd;
a42e9d6c	69
662ad4f8 SH	70	unsigned long head, tail;
	71	struct tcp_log *log;
	72	} tcp_probe;
	73
14a49e1f	74
662ad4f8	75	static inline int tcp_probe_used(void)
a42e9d6c	76	{
662ad4f8 SH	77	return (tcp_probe.head - tcp_probe.tail) % bufsize;
	78	}
	79
	80	static inline int tcp_probe_avail(void)
	81	{
	82	return bufsize - tcp_probe_used();
14a49e1f	83	}
a42e9d6c	84
85795d64 SH	85	/*
	86	* Hook inserted to be called before each receive packet.
	87	* Note: arguments must match tcp_rcv_established()!
	88	*/
	89	static int jtcp_rcv_established(struct sock sk, struct sk_buff skb,
	90	struct tcphdr *th, unsigned len)
a42e9d6c SH	91	{
	92	const struct tcp_sock *tp = tcp_sk(sk);
	93	const struct inet_sock *inet = inet_sk(sk);
	94
85795d64 SH	95	/* Only update if port matches */
85795d64 SH	96	if ((port == 0 \|\| ntohs(inet->dport) == port \|\| ntohs(inet->sport) == port)
662ad4f8 SH	97	&& (full \|\| tp->snd_cwnd != tcp_probe.lastcwnd)) {
	98
	99	spin_lock(&tcp_probe.lock);
	100	/* If log fills, just silently drop */
	101	if (tcp_probe_avail() > 1) {
	102	struct tcp_log *p = tcp_probe.log + tcp_probe.head;
	103
	104	p->tstamp = ktime_get();
	105	p->saddr = inet->saddr;
	106	p->sport = inet->sport;
	107	p->daddr = inet->daddr;
	108	p->dport = inet->dport;
	109	p->length = skb->len;
	110	p->snd_nxt = tp->snd_nxt;
	111	p->snd_una = tp->snd_una;
	112	p->snd_cwnd = tp->snd_cwnd;
	113	p->snd_wnd = tp->snd_wnd;
b3b0b681	114	p->ssthresh = tcp_current_ssthresh(sk);
662ad4f8 SH	115	p->srtt = tp->srtt >> 3;
	116
	117	tcp_probe.head = (tcp_probe.head + 1) % bufsize;
	118	}
	119	tcp_probe.lastcwnd = tp->snd_cwnd;
	120	spin_unlock(&tcp_probe.lock);
	121
	122	wake_up(&tcp_probe.wait);
a42e9d6c SH	123	}
	124
	125	jprobe_return();
	126	return 0;
	127	}
	128
662ad4f8	129	static struct jprobe tcp_jprobe = {
3a872d89	130	.kp = {
85795d64	131	.symbol_name = "tcp_rcv_established",
3a872d89	132	},
9e367d85	133	.entry = jtcp_rcv_established,
a42e9d6c SH	134	};
a42e9d6c SH	135
a42e9d6c SH	136	static int tcpprobe_open(struct inode * inode, struct file * file)
a42e9d6c SH	137	{
662ad4f8 SH	138	/* Reset (empty) log */
	139	spin_lock_bh(&tcp_probe.lock);
	140	tcp_probe.head = tcp_probe.tail = 0;
	141	tcp_probe.start = ktime_get();
	142	spin_unlock_bh(&tcp_probe.lock);
	143
a42e9d6c SH	144	return 0;
	145	}
	146
662ad4f8 SH	147	static int tcpprobe_sprint(char *tbuf, int n)
	148	{
	149	const struct tcp_log *p
	150	= tcp_probe.log + tcp_probe.tail % bufsize;
	151	struct timespec tv
	152	= ktime_to_timespec(ktime_sub(p->tstamp, tcp_probe.start));
	153
	154	return snprintf(tbuf, n,
	155	"%lu.%09lu %d.%d.%d.%d:%u %d.%d.%d.%d:%u"
	156	" %d %#x %#x %u %u %u %u\n",
	157	(unsigned long) tv.tv_sec,
	158	(unsigned long) tv.tv_nsec,
	159	NIPQUAD(p->saddr), ntohs(p->sport),
	160	NIPQUAD(p->daddr), ntohs(p->dport),
	161	p->length, p->snd_nxt, p->snd_una,
	162	p->snd_cwnd, p->ssthresh, p->snd_wnd, p->srtt);
	163	}
	164
a42e9d6c SH	165	static ssize_t tcpprobe_read(struct file file, char __user buf,
	166	size_t len, loff_t *ppos)
	167	{
118075b3	168	int error = 0, cnt = 0;
a42e9d6c SH	169
	170	if (!buf \|\| len < 0)
	171	return -EINVAL;
	172
662ad4f8 SH	173	while (cnt < len) {
	174	char tbuf[128];
	175	int width;
	176
	177	/* Wait for data in buffer */
	178	error = wait_event_interruptible(tcp_probe.wait,
	179	tcp_probe_used() > 0);
	180	if (error)
	181	break;
a42e9d6c	182
662ad4f8 SH	183	spin_lock_bh(&tcp_probe.lock);
	184	if (tcp_probe.head == tcp_probe.tail) {
	185	/* multiple readers race? */
	186	spin_unlock_bh(&tcp_probe.lock);
	187	continue;
	188	}
a42e9d6c	189
662ad4f8	190	width = tcpprobe_sprint(tbuf, sizeof(tbuf));
a42e9d6c	191
662ad4f8 SH	192	if (width < len)
662ad4f8 SH	193	tcp_probe.tail = (tcp_probe.tail + 1) % bufsize;
a42e9d6c	194
662ad4f8 SH	195	spin_unlock_bh(&tcp_probe.lock);
	196
	197	/* if record greater than space available
	198	return partial buffer (so far) */
	199	if (width >= len)
	200	break;
	201
	202	error = copy_to_user(buf + cnt, tbuf, width);
	203	if (error)
	204	break;
	205	cnt += width;
	206	}
a42e9d6c	207
662ad4f8	208	return cnt == 0 ? error : cnt;
a42e9d6c SH	209	}
a42e9d6c SH	210
9a32144e	211	static const struct file_operations tcpprobe_fops = {
a42e9d6c SH	212	.owner = THIS_MODULE,
	213	.open = tcpprobe_open,
	214	.read = tcpprobe_read,
	215	};
	216
	217	static __init int tcpprobe_init(void)
	218	{
	219	int ret = -ENOMEM;
	220
662ad4f8 SH	221	init_waitqueue_head(&tcp_probe.wait);
	222	spin_lock_init(&tcp_probe.lock);
	223
	224	if (bufsize < 0)
	225	return -EINVAL;
	226
	227	tcp_probe.log = kcalloc(sizeof(struct tcp_log), bufsize, GFP_KERNEL);
	228	if (!tcp_probe.log)
	229	goto err0;
a42e9d6c SH	230
	231	if (!proc_net_fops_create(procname, S_IRUSR, &tcpprobe_fops))
	232	goto err0;
	233
662ad4f8	234	ret = register_jprobe(&tcp_jprobe);
a42e9d6c SH	235	if (ret)
	236	goto err1;
	237
662ad4f8	238	pr_info("TCP probe registered (port=%d)\n", port);
a42e9d6c SH	239	return 0;
	240	err1:
	241	proc_net_remove(procname);
	242	err0:
662ad4f8	243	kfree(tcp_probe.log);
a42e9d6c SH	244	return ret;
	245	}
	246	module_init(tcpprobe_init);
	247
	248	static __exit void tcpprobe_exit(void)
	249	{
a42e9d6c	250	proc_net_remove(procname);
662ad4f8 SH	251	unregister_jprobe(&tcp_jprobe);
662ad4f8 SH	252	kfree(tcp_probe.log);
a42e9d6c SH	253	}
a42e9d6c SH	254	module_exit(tcpprobe_exit);