linux/net/sctp/probe.c
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   1/*
   2 * sctp_probe - Observe the SCTP 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 * Modified for SCTP from Stephen Hemminger's code
   8 * Copyright (C) 2010, Wei Yongjun <yjwei@cn.fujitsu.com>
   9 *
  10 * This program is free software; you can redistribute it and/or modify
  11 * it under the terms of the GNU General Public License as published by
  12 * the Free Software Foundation; either version 2 of the License, or
  13 * (at your option) any later version.
  14 *
  15 * This program is distributed in the hope that it will be useful,
  16 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18 * GNU General Public License for more details.
  19 *
  20 * You should have received a copy of the GNU General Public License
  21 * along with this program; if not, write to the Free Software
  22 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  23 */
  24
  25#include <linux/kernel.h>
  26#include <linux/kprobes.h>
  27#include <linux/socket.h>
  28#include <linux/sctp.h>
  29#include <linux/proc_fs.h>
  30#include <linux/vmalloc.h>
  31#include <linux/module.h>
  32#include <linux/kfifo.h>
  33#include <linux/time.h>
  34#include <net/net_namespace.h>
  35
  36#include <net/sctp/sctp.h>
  37#include <net/sctp/sm.h>
  38
  39MODULE_AUTHOR("Wei Yongjun <yjwei@cn.fujitsu.com>");
  40MODULE_DESCRIPTION("SCTP snooper");
  41MODULE_LICENSE("GPL");
  42
  43static int port __read_mostly = 0;
  44MODULE_PARM_DESC(port, "Port to match (0=all)");
  45module_param(port, int, 0);
  46
  47static int bufsize __read_mostly = 64 * 1024;
  48MODULE_PARM_DESC(bufsize, "Log buffer size (default 64k)");
  49module_param(bufsize, int, 0);
  50
  51static int full __read_mostly = 1;
  52MODULE_PARM_DESC(full, "Full log (1=every ack packet received,  0=only cwnd changes)");
  53module_param(full, int, 0);
  54
  55static const char procname[] = "sctpprobe";
  56
  57static struct {
  58        struct kfifo      fifo;
  59        spinlock_t        lock;
  60        wait_queue_head_t wait;
  61        struct timespec   tstart;
  62} sctpw;
  63
  64static void printl(const char *fmt, ...)
  65{
  66        va_list args;
  67        int len;
  68        char tbuf[256];
  69
  70        va_start(args, fmt);
  71        len = vscnprintf(tbuf, sizeof(tbuf), fmt, args);
  72        va_end(args);
  73
  74        kfifo_in_locked(&sctpw.fifo, tbuf, len, &sctpw.lock);
  75        wake_up(&sctpw.wait);
  76}
  77
  78static int sctpprobe_open(struct inode *inode, struct file *file)
  79{
  80        kfifo_reset(&sctpw.fifo);
  81        getnstimeofday(&sctpw.tstart);
  82
  83        return 0;
  84}
  85
  86static ssize_t sctpprobe_read(struct file *file, char __user *buf,
  87                              size_t len, loff_t *ppos)
  88{
  89        int error = 0, cnt = 0;
  90        unsigned char *tbuf;
  91
  92        if (!buf)
  93                return -EINVAL;
  94
  95        if (len == 0)
  96                return 0;
  97
  98        tbuf = vmalloc(len);
  99        if (!tbuf)
 100                return -ENOMEM;
 101
 102        error = wait_event_interruptible(sctpw.wait,
 103                                         kfifo_len(&sctpw.fifo) != 0);
 104        if (error)
 105                goto out_free;
 106
 107        cnt = kfifo_out_locked(&sctpw.fifo, tbuf, len, &sctpw.lock);
 108        error = copy_to_user(buf, tbuf, cnt) ? -EFAULT : 0;
 109
 110out_free:
 111        vfree(tbuf);
 112
 113        return error ? error : cnt;
 114}
 115
 116static const struct file_operations sctpprobe_fops = {
 117        .owner  = THIS_MODULE,
 118        .open   = sctpprobe_open,
 119        .read   = sctpprobe_read,
 120};
 121
 122sctp_disposition_t jsctp_sf_eat_sack(const struct sctp_endpoint *ep,
 123                                     const struct sctp_association *asoc,
 124                                     const sctp_subtype_t type,
 125                                     void *arg,
 126                                     sctp_cmd_seq_t *commands)
 127{
 128        struct sctp_transport *sp;
 129        static __u32 lcwnd = 0;
 130        struct timespec now;
 131
 132        sp = asoc->peer.primary_path;
 133
 134        if ((full || sp->cwnd != lcwnd) &&
 135            (!port || asoc->peer.port == port ||
 136             ep->base.bind_addr.port == port)) {
 137                lcwnd = sp->cwnd;
 138
 139                getnstimeofday(&now);
 140                now = timespec_sub(now, sctpw.tstart);
 141
 142                printl("%lu.%06lu ", (unsigned long) now.tv_sec,
 143                       (unsigned long) now.tv_nsec / NSEC_PER_USEC);
 144
 145                printl("%p %5d %5d %5d %8d %5d ", asoc,
 146                       ep->base.bind_addr.port, asoc->peer.port,
 147                       asoc->pathmtu, asoc->peer.rwnd, asoc->unack_data);
 148
 149                list_for_each_entry(sp, &asoc->peer.transport_addr_list,
 150                                        transports) {
 151                        if (sp == asoc->peer.primary_path)
 152                                printl("*");
 153
 154                        if (sp->ipaddr.sa.sa_family == AF_INET)
 155                                printl("%pI4 ", &sp->ipaddr.v4.sin_addr);
 156                        else
 157                                printl("%pI6 ", &sp->ipaddr.v6.sin6_addr);
 158
 159                        printl("%2u %8u %8u %8u %8u %8u ",
 160                               sp->state, sp->cwnd, sp->ssthresh,
 161                               sp->flight_size, sp->partial_bytes_acked,
 162                               sp->pathmtu);
 163                }
 164                printl("\n");
 165        }
 166
 167        jprobe_return();
 168        return 0;
 169}
 170
 171static struct jprobe sctp_recv_probe = {
 172        .kp     = {
 173                .symbol_name = "sctp_sf_eat_sack_6_2",
 174        },
 175        .entry  = jsctp_sf_eat_sack,
 176};
 177
 178static __init int sctpprobe_init(void)
 179{
 180        int ret = -ENOMEM;
 181
 182        init_waitqueue_head(&sctpw.wait);
 183        spin_lock_init(&sctpw.lock);
 184        if (kfifo_alloc(&sctpw.fifo, bufsize, GFP_KERNEL))
 185                return ret;
 186
 187        if (!proc_net_fops_create(&init_net, procname, S_IRUSR,
 188                                  &sctpprobe_fops))
 189                goto free_kfifo;
 190
 191        ret = register_jprobe(&sctp_recv_probe);
 192        if (ret)
 193                goto remove_proc;
 194
 195        pr_info("SCTP probe registered (port=%d)\n", port);
 196
 197        return 0;
 198
 199remove_proc:
 200        proc_net_remove(&init_net, procname);
 201free_kfifo:
 202        kfifo_free(&sctpw.fifo);
 203        return ret;
 204}
 205
 206static __exit void sctpprobe_exit(void)
 207{
 208        kfifo_free(&sctpw.fifo);
 209        proc_net_remove(&init_net, procname);
 210        unregister_jprobe(&sctp_recv_probe);
 211}
 212
 213module_init(sctpprobe_init);
 214module_exit(sctpprobe_exit);
 215