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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  26
  27#include <linux/kernel.h>
  28#include <linux/kprobes.h>
  29#include <linux/socket.h>
  30#include <linux/sctp.h>
  31#include <linux/proc_fs.h>
  32#include <linux/vmalloc.h>
  33#include <linux/module.h>
  34#include <linux/kfifo.h>
  35#include <linux/time.h>
  36#include <net/net_namespace.h>
  37
  38#include <net/sctp/sctp.h>
  39#include <net/sctp/sm.h>
  40
  41MODULE_AUTHOR("Wei Yongjun <yjwei@cn.fujitsu.com>");
  42MODULE_DESCRIPTION("SCTP snooper");
  43MODULE_LICENSE("GPL");
  44
  45static int port __read_mostly = 0;
  46MODULE_PARM_DESC(port, "Port to match (0=all)");
  47module_param(port, int, 0);
  48
  49static int bufsize __read_mostly = 64 * 1024;
  50MODULE_PARM_DESC(bufsize, "Log buffer size (default 64k)");
  51module_param(bufsize, int, 0);
  52
  53static int full __read_mostly = 1;
  54MODULE_PARM_DESC(full, "Full log (1=every ack packet received,  0=only cwnd changes)");
  55module_param(full, int, 0);
  56
  57static const char procname[] = "sctpprobe";
  58
  59static struct {
  60        struct kfifo      fifo;
  61        spinlock_t        lock;
  62        wait_queue_head_t wait;
  63        struct timespec   tstart;
  64} sctpw;
  65
  66static void printl(const char *fmt, ...)
  67{
  68        va_list args;
  69        int len;
  70        char tbuf[256];
  71
  72        va_start(args, fmt);
  73        len = vscnprintf(tbuf, sizeof(tbuf), fmt, args);
  74        va_end(args);
  75
  76        kfifo_in_locked(&sctpw.fifo, tbuf, len, &sctpw.lock);
  77        wake_up(&sctpw.wait);
  78}
  79
  80static int sctpprobe_open(struct inode *inode, struct file *file)
  81{
  82        kfifo_reset(&sctpw.fifo);
  83        getnstimeofday(&sctpw.tstart);
  84
  85        return 0;
  86}
  87
  88static ssize_t sctpprobe_read(struct file *file, char __user *buf,
  89                              size_t len, loff_t *ppos)
  90{
  91        int error = 0, cnt = 0;
  92        unsigned char *tbuf;
  93
  94        if (!buf)
  95                return -EINVAL;
  96
  97        if (len == 0)
  98                return 0;
  99
 100        tbuf = vmalloc(len);
 101        if (!tbuf)
 102                return -ENOMEM;
 103
 104        error = wait_event_interruptible(sctpw.wait,
 105                                         kfifo_len(&sctpw.fifo) != 0);
 106        if (error)
 107                goto out_free;
 108
 109        cnt = kfifo_out_locked(&sctpw.fifo, tbuf, len, &sctpw.lock);
 110        error = copy_to_user(buf, tbuf, cnt) ? -EFAULT : 0;
 111
 112out_free:
 113        vfree(tbuf);
 114
 115        return error ? error : cnt;
 116}
 117
 118static const struct file_operations sctpprobe_fops = {
 119        .owner  = THIS_MODULE,
 120        .open   = sctpprobe_open,
 121        .read   = sctpprobe_read,
 122        .llseek = noop_llseek,
 123};
 124
 125sctp_disposition_t jsctp_sf_eat_sack(const struct sctp_endpoint *ep,
 126                                     const struct sctp_association *asoc,
 127                                     const sctp_subtype_t type,
 128                                     void *arg,
 129                                     sctp_cmd_seq_t *commands)
 130{
 131        struct sctp_transport *sp;
 132        static __u32 lcwnd = 0;
 133        struct timespec now;
 134
 135        sp = asoc->peer.primary_path;
 136
 137        if ((full || sp->cwnd != lcwnd) &&
 138            (!port || asoc->peer.port == port ||
 139             ep->base.bind_addr.port == port)) {
 140                lcwnd = sp->cwnd;
 141
 142                getnstimeofday(&now);
 143                now = timespec_sub(now, sctpw.tstart);
 144
 145                printl("%lu.%06lu ", (unsigned long) now.tv_sec,
 146                       (unsigned long) now.tv_nsec / NSEC_PER_USEC);
 147
 148                printl("%p %5d %5d %5d %8d %5d ", asoc,
 149                       ep->base.bind_addr.port, asoc->peer.port,
 150                       asoc->pathmtu, asoc->peer.rwnd, asoc->unack_data);
 151
 152                list_for_each_entry(sp, &asoc->peer.transport_addr_list,
 153                                        transports) {
 154                        if (sp == asoc->peer.primary_path)
 155                                printl("*");
 156
 157                        if (sp->ipaddr.sa.sa_family == AF_INET)
 158                                printl("%pI4 ", &sp->ipaddr.v4.sin_addr);
 159                        else
 160                                printl("%pI6 ", &sp->ipaddr.v6.sin6_addr);
 161
 162                        printl("%2u %8u %8u %8u %8u %8u ",
 163                               sp->state, sp->cwnd, sp->ssthresh,
 164                               sp->flight_size, sp->partial_bytes_acked,
 165                               sp->pathmtu);
 166                }
 167                printl("\n");
 168        }
 169
 170        jprobe_return();
 171        return 0;
 172}
 173
 174static struct jprobe sctp_recv_probe = {
 175        .kp     = {
 176                .symbol_name = "sctp_sf_eat_sack_6_2",
 177        },
 178        .entry  = jsctp_sf_eat_sack,
 179};
 180
 181static __init int sctpprobe_init(void)
 182{
 183        int ret = -ENOMEM;
 184
 185        init_waitqueue_head(&sctpw.wait);
 186        spin_lock_init(&sctpw.lock);
 187        if (kfifo_alloc(&sctpw.fifo, bufsize, GFP_KERNEL))
 188                return ret;
 189
 190        if (!proc_net_fops_create(&init_net, procname, S_IRUSR,
 191                                  &sctpprobe_fops))
 192                goto free_kfifo;
 193
 194        ret = register_jprobe(&sctp_recv_probe);
 195        if (ret)
 196                goto remove_proc;
 197
 198        pr_info("probe registered (port=%d)\n", port);
 199
 200        return 0;
 201
 202remove_proc:
 203        proc_net_remove(&init_net, procname);
 204free_kfifo:
 205        kfifo_free(&sctpw.fifo);
 206        return ret;
 207}
 208
 209static __exit void sctpprobe_exit(void)
 210{
 211        kfifo_free(&sctpw.fifo);
 212        proc_net_remove(&init_net, procname);
 213        unregister_jprobe(&sctp_recv_probe);
 214}
 215
 216module_init(sctpprobe_init);
 217module_exit(sctpprobe_exit);
 218
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