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 #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
  39 MODULE_AUTHOR("Wei Yongjun <yjwei@cn.fujitsu.com>");
  40 MODULE_DESCRIPTION("SCTP snooper");
  41 MODULE_LICENSE("GPL");
  42
  43 static int port __read_mostly = 0;
  44 MODULE_PARM_DESC(port, "Port to match (0=all)");
  45 module_param(port, int, 0);
  46
  47 static int bufsize __read_mostly = 64 * 1024;
  48 MODULE_PARM_DESC(bufsize, "Log buffer size (default 64k)");
  49 module_param(bufsize, int, 0);
  50
  51 static int full __read_mostly = 1;
  52 MODULE_PARM_DESC(full, "Full log (1=every ack packet received,  0=only cwnd changes)");
  53 module_param(full, int, 0);
  54
  55 static const char procname[] = "sctpprobe";
  56
  57 static struct {
  58         struct kfifo      fifo;
  59         spinlock_t        lock;
  60         wait_queue_head_t wait;
  61         struct timespec   tstart;
  62 } sctpw;
  63
  64 static 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
  78 static 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
  86 static 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
 110 out_free:
 111         vfree(tbuf);
 112
 113         return error ? error : cnt;
 114 }
 115
 116 static const struct file_operations sctpprobe_fops = {
 117         .owner  = THIS_MODULE,
 118         .open   = sctpprobe_open,
 119         .read   = sctpprobe_read,
 120         .llseek = noop_llseek,
 121 };
 122
 123 sctp_disposition_t jsctp_sf_eat_sack(const struct sctp_endpoint *ep,
 124                                      const struct sctp_association *asoc,
 125                                      const sctp_subtype_t type,
 126                                      void *arg,
 127                                      sctp_cmd_seq_t *commands)
 128 {
 129         struct sctp_transport *sp;
 130         static __u32 lcwnd = 0;
 131         struct timespec now;
 132
 133         sp = asoc->peer.primary_path;
 134
 135         if ((full || sp->cwnd != lcwnd) &&
 136             (!port || asoc->peer.port == port ||
 137              ep->base.bind_addr.port == port)) {
 138                 lcwnd = sp->cwnd;
 139
 140                 getnstimeofday(&now);
 141                 now = timespec_sub(now, sctpw.tstart);
 142
 143                 printl("%lu.%06lu ", (unsigned long) now.tv_sec,
 144                        (unsigned long) now.tv_nsec / NSEC_PER_USEC);
 145
 146                 printl("%p %5d %5d %5d %8d %5d ", asoc,
 147                        ep->base.bind_addr.port, asoc->peer.port,
 148                        asoc->pathmtu, asoc->peer.rwnd, asoc->unack_data);
 149
 150                 list_for_each_entry(sp, &asoc->peer.transport_addr_list,
 151                                         transports) {
 152                         if (sp == asoc->peer.primary_path)
 153                                 printl("*");
 154
 155                         if (sp->ipaddr.sa.sa_family == AF_INET)
 156                                 printl("%pI4 ", &sp->ipaddr.v4.sin_addr);
 157                         else
 158                                 printl("%pI6 ", &sp->ipaddr.v6.sin6_addr);
 159
 160                         printl("%2u %8u %8u %8u %8u %8u ",
 161                                sp->state, sp->cwnd, sp->ssthresh,
 162                                sp->flight_size, sp->partial_bytes_acked,
 163                                sp->pathmtu);
 164                 }
 165                 printl("\n");
 166         }
 167
 168         jprobe_return();
 169         return 0;
 170 }
 171
 172 static struct jprobe sctp_recv_probe = {
 173         .kp     = {
 174                 .symbol_name = "sctp_sf_eat_sack_6_2",
 175         },
 176         .entry  = jsctp_sf_eat_sack,
 177 };
 178
 179 static __init int sctpprobe_init(void)
 180 {
 181         int ret = -ENOMEM;
 182
 183         init_waitqueue_head(&sctpw.wait);
 184         spin_lock_init(&sctpw.lock);
 185         if (kfifo_alloc(&sctpw.fifo, bufsize, GFP_KERNEL))
 186                 return ret;
 187
 188         if (!proc_net_fops_create(&init_net, procname, S_IRUSR,
 189                                   &sctpprobe_fops))
 190                 goto free_kfifo;
 191
 192         ret = register_jprobe(&sctp_recv_probe);
 193         if (ret)
 194                 goto remove_proc;
 195
 196         pr_info("SCTP probe registered (port=%d)\n", port);
 197
 198         return 0;
 199
 200 remove_proc:
 201         proc_net_remove(&init_net, procname);
 202 free_kfifo:
 203         kfifo_free(&sctpw.fifo);
 204         return ret;
 205 }
 206
 207 static __exit void sctpprobe_exit(void)
 208 {
 209         kfifo_free(&sctpw.fifo);
 210         proc_net_remove(&init_net, procname);
 211         unregister_jprobe(&sctp_recv_probe);
 212 }
 213
 214 module_init(sctpprobe_init);
 215 module_exit(sctpprobe_exit);