--- /dev/null
+/*
+ * 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.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/kprobes.h>
+#include <linux/socket.h>
+#include <linux/tcp.h>
+#include <linux/slab.h>
+#include <linux/proc_fs.h>
+#include <linux/module.h>
+#include <linux/ktime.h>
+#include <linux/time.h>
+#include <net/net_namespace.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;
+MODULE_PARM_DESC(port, "Port to match (0=all)");
+module_param(port, int, 0);
+
+static unsigned int bufsize __read_mostly = 4096;
+MODULE_PARM_DESC(bufsize, "Log buffer size in packets (4096)");
+module_param(bufsize, uint, 0);
+
+static unsigned int fwmark __read_mostly;
+MODULE_PARM_DESC(fwmark, "skb mark to match (0=no mark)");
+module_param(fwmark, uint, 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;
+ union {
+ struct sockaddr raw;
+ struct sockaddr_in v4;
+ struct sockaddr_in6 v6;
+ } src, dst;
+ u16 length;
+ u32 snd_nxt;
+ u32 snd_una;
+ u32 snd_wnd;
+ u32 rcv_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 - 1);
+}
+
+static inline int tcp_probe_avail(void)
+{
+ return bufsize - tcp_probe_used() - 1;
+}
+
+#define tcp_probe_copy_fl_to_si4(inet, si4, mem) \
+ do { \
+ si4.sin_family = AF_INET; \
+ si4.sin_port = inet->inet_##mem##port; \
+ si4.sin_addr.s_addr = inet->inet_##mem##addr; \
+ } while (0) \
+
+/*
+ * Hook inserted to be called before each receive packet.
+ * Note: arguments must match tcp_rcv_established()!
+ */
+static void jtcp_rcv_established(struct sock *sk, struct sk_buff *skb,
+ const struct tcphdr *th, unsigned int len)
+{
+ const struct tcp_sock *tp = tcp_sk(sk);
+ const struct inet_sock *inet = inet_sk(sk);
+
+ /* Only update if port or skb mark matches */
+ if (((port == 0 && fwmark == 0) ||
+ ntohs(inet->inet_dport) == port ||
+ ntohs(inet->inet_sport) == port ||
+ (fwmark > 0 && skb->mark == fwmark)) &&
+ (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();
+ switch (sk->sk_family) {
+ case AF_INET:
+ tcp_probe_copy_fl_to_si4(inet, p->src.v4, s);
+ tcp_probe_copy_fl_to_si4(inet, p->dst.v4, d);
+ break;
+ case AF_INET6:
+ memset(&p->src.v6, 0, sizeof(p->src.v6));
+ memset(&p->dst.v6, 0, sizeof(p->dst.v6));
+#if IS_ENABLED(CONFIG_IPV6)
+ p->src.v6.sin6_family = AF_INET6;
+ p->src.v6.sin6_port = inet->inet_sport;
+ p->src.v6.sin6_addr = inet6_sk(sk)->saddr;
+
+ p->dst.v6.sin6_family = AF_INET6;
+ p->dst.v6.sin6_port = inet->inet_dport;
+ p->dst.v6.sin6_addr = sk->sk_v6_daddr;
+#endif
+ break;
+ default:
+ BUG();
+ }
+
+ 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->rcv_wnd = tp->rcv_wnd;
+ p->ssthresh = tcp_current_ssthresh(sk);
+ p->srtt = tp->srtt_us >> 3;
+
+ tcp_probe.head = (tcp_probe.head + 1) & (bufsize - 1);
+ }
+ tcp_probe.lastcwnd = tp->snd_cwnd;
+ spin_unlock(&tcp_probe.lock);
+
+ wake_up(&tcp_probe.wait);
+ }
+
+ jprobe_return();
+}
+
+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;
+ struct timespec tv
+ = ktime_to_timespec(ktime_sub(p->tstamp, tcp_probe.start));
+
+ return scnprintf(tbuf, n,
+ "%lu.%09lu %pISpc %pISpc %d %#x %#x %u %u %u %u %u\n",
+ (unsigned long)tv.tv_sec,
+ (unsigned long)tv.tv_nsec,
+ &p->src, &p->dst, p->length, p->snd_nxt, p->snd_una,
+ p->snd_cwnd, p->ssthresh, p->snd_wnd, p->srtt, p->rcv_wnd);
+}
+
+static ssize_t tcpprobe_read(struct file *file, char __user *buf,
+ size_t len, loff_t *ppos)
+{
+ int error = 0;
+ size_t cnt = 0;
+
+ if (!buf)
+ return -EINVAL;
+
+ while (cnt < len) {
+ char tbuf[256];
+ 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 (cnt + width < len)
+ tcp_probe.tail = (tcp_probe.tail + 1) & (bufsize - 1);
+
+ spin_unlock_bh(&tcp_probe.lock);
+
+ /* if record greater than space available
+ return partial buffer (so far) */
+ if (cnt + width >= len)
+ break;
+
+ if (copy_to_user(buf + cnt, tbuf, width))
+ return -EFAULT;
+ cnt += width;
+ }
+
+ return cnt == 0 ? error : cnt;
+}
+
+static const struct file_operations tcpprobe_fops = {
+ .owner = THIS_MODULE,
+ .open = tcpprobe_open,
+ .read = tcpprobe_read,
+ .llseek = noop_llseek,
+};
+
+static __init int tcpprobe_init(void)
+{
+ int ret = -ENOMEM;
+
+ /* Warning: if the function signature of tcp_rcv_established,
+ * has been changed, you also have to change the signature of
+ * jtcp_rcv_established, otherwise you end up right here!
+ */
+ BUILD_BUG_ON(__same_type(tcp_rcv_established,
+ jtcp_rcv_established) == 0);
+
+ init_waitqueue_head(&tcp_probe.wait);
+ spin_lock_init(&tcp_probe.lock);
+
+ if (bufsize == 0)
+ return -EINVAL;
+
+ bufsize = roundup_pow_of_two(bufsize);
+ tcp_probe.log = kcalloc(bufsize, sizeof(struct tcp_log), GFP_KERNEL);
+ if (!tcp_probe.log)
+ goto err0;
+
+ if (!proc_create(procname, S_IRUSR, init_net.proc_net, &tcpprobe_fops))
+ goto err0;
+
+ ret = register_jprobe(&tcp_jprobe);
+ if (ret)
+ goto err1;
+
+ pr_info("probe registered (port=%d/fwmark=%u) bufsize=%u\n",
+ port, fwmark, bufsize);
+ return 0;
+ err1:
+ remove_proc_entry(procname, init_net.proc_net);
+ err0:
+ kfree(tcp_probe.log);
+ return ret;
+}
+module_init(tcpprobe_init);
+
+static __exit void tcpprobe_exit(void)
+{
+ remove_proc_entry(procname, init_net.proc_net);
+ unregister_jprobe(&tcp_jprobe);
+ kfree(tcp_probe.log);
+}
+module_exit(tcpprobe_exit);
Code Review / kvmfornfv.git / blobdiff