net/sctp/probe.c

   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
  41 MODULE_AUTHOR("Wei Yongjun <yjwei@cn.fujitsu.com>");
  42 MODULE_DESCRIPTION("SCTP snooper");
  43 MODULE_LICENSE("GPL");
  44
  45 static int port __read_mostly = 0;
  46 MODULE_PARM_DESC(port, "Port to match (0=all)");
  47 module_param(port, int, 0);
  48
  49 static int bufsize __read_mostly = 64 * 1024;
  50 MODULE_PARM_DESC(bufsize, "Log buffer size (default 64k)");
  51 module_param(bufsize, int, 0);
  52
  53 static int full __read_mostly = 1;
  54 MODULE_PARM_DESC(full, "Full log (1=every ack packet received,  0=only cwnd changes)");
  55 module_param(full, int, 0);
  56
  57 static const char procname[] = "sctpprobe";
  58
  59 static struct {
  60         struct kfifo      fifo;
  61         spinlock_t        lock;
  62         wait_queue_head_t wait;
  63         struct timespec   tstart;
  64 } sctpw;
  65
  66 static 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
  80 static 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
  88 static 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
 112 out_free:
 113         vfree(tbuf);
 114
 115         return error ? error : cnt;
 116 }
 117
 118 static const struct file_operations sctpprobe_fops = {
 119         .owner  = THIS_MODULE,
 120         .open   = sctpprobe_open,
 121         .read   = sctpprobe_read,
 122         .llseek = noop_llseek,
 123 };
 124
 125 sctp_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
 174 static 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
 181 static __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
 202 remove_proc:
 203         proc_net_remove(&init_net, procname);
 204 free_kfifo:
 205         kfifo_free(&sctpw.fifo);
 206         return ret;
 207 }
 208
 209 static __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
 216 module_init(sctpprobe_init);
 217 module_exit(sctpprobe_exit);