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 unsigned int fwmark __read_mostly = 0;
  50 MODULE_PARM_DESC(fwmark, "skb mark to match (0=no mark)");
  51 module_param(fwmark, uint, 0);
  52
  53 static int bufsize __read_mostly = 64 * 1024;
  54 MODULE_PARM_DESC(bufsize, "Log buffer size (default 64k)");
  55 module_param(bufsize, int, 0);
  56
  57 static int full __read_mostly = 1;
  58 MODULE_PARM_DESC(full, "Full log (1=every ack packet received,  0=only cwnd changes)");
  59 module_param(full, int, 0);
  60
  61 static const char procname[] = "sctpprobe";
  62
  63 static struct {
  64         struct kfifo      fifo;
  65         spinlock_t        lock;
  66         wait_queue_head_t wait;
  67         struct timespec   tstart;
  68 } sctpw;
  69
  70 static __printf(1, 2) void printl(const char *fmt, ...)
  71 {
  72         va_list args;
  73         int len;
  74         char tbuf[256];
  75
  76         va_start(args, fmt);
  77         len = vscnprintf(tbuf, sizeof(tbuf), fmt, args);
  78         va_end(args);
  79
  80         kfifo_in_locked(&sctpw.fifo, tbuf, len, &sctpw.lock);
  81         wake_up(&sctpw.wait);
  82 }
  83
  84 static int sctpprobe_open(struct inode *inode, struct file *file)
  85 {
  86         kfifo_reset(&sctpw.fifo);
  87         getnstimeofday(&sctpw.tstart);
  88
  89         return 0;
  90 }
  91
  92 static ssize_t sctpprobe_read(struct file *file, char __user *buf,
  93                               size_t len, loff_t *ppos)
  94 {
  95         int error = 0, cnt = 0;
  96         unsigned char *tbuf;
  97
  98         if (!buf)
  99                 return -EINVAL;
 100
 101         if (len == 0)
 102                 return 0;
 103
 104         tbuf = vmalloc(len);
 105         if (!tbuf)
 106                 return -ENOMEM;
 107
 108         error = wait_event_interruptible(sctpw.wait,
 109                                          kfifo_len(&sctpw.fifo) != 0);
 110         if (error)
 111                 goto out_free;
 112
 113         cnt = kfifo_out_locked(&sctpw.fifo, tbuf, len, &sctpw.lock);
 114         error = copy_to_user(buf, tbuf, cnt) ? -EFAULT : 0;
 115
 116 out_free:
 117         vfree(tbuf);
 118
 119         return error ? error : cnt;
 120 }
 121
 122 static const struct file_operations sctpprobe_fops = {
 123         .owner  = THIS_MODULE,
 124         .open   = sctpprobe_open,
 125         .read   = sctpprobe_read,
 126         .llseek = noop_llseek,
 127 };
 128
 129 static sctp_disposition_t jsctp_sf_eat_sack(struct net *net,
 130                                             const struct sctp_endpoint *ep,
 131                                             const struct sctp_association *asoc,
 132                                             const sctp_subtype_t type,
 133                                             void *arg,
 134                                             sctp_cmd_seq_t *commands)
 135 {
 136         struct sctp_chunk *chunk = arg;
 137         struct sk_buff *skb = chunk->skb;
 138         struct sctp_transport *sp;
 139         static __u32 lcwnd = 0;
 140         struct timespec now;
 141
 142         sp = asoc->peer.primary_path;
 143
 144         if (((port == 0 && fwmark == 0) ||
 145              asoc->peer.port == port ||
 146              ep->base.bind_addr.port == port ||
 147              (fwmark > 0 && skb->mark == fwmark)) &&
 148             (full || sp->cwnd != lcwnd)) {
 149                 lcwnd = sp->cwnd;
 150
 151                 getnstimeofday(&now);
 152                 now = timespec_sub(now, sctpw.tstart);
 153
 154                 printl("%lu.%06lu ", (unsigned long) now.tv_sec,
 155                        (unsigned long) now.tv_nsec / NSEC_PER_USEC);
 156
 157                 printl("%p %5d %5d %5d %8d %5d ", asoc,
 158                        ep->base.bind_addr.port, asoc->peer.port,
 159                        asoc->pathmtu, asoc->peer.rwnd, asoc->unack_data);
 160
 161                 list_for_each_entry(sp, &asoc->peer.transport_addr_list,
 162                                         transports) {
 163                         if (sp == asoc->peer.primary_path)
 164                                 printl("*");
 165
 166                         printl("%pISc %2u %8u %8u %8u %8u %8u ",
 167                                &sp->ipaddr, sp->state, sp->cwnd, sp->ssthresh,
 168                                sp->flight_size, sp->partial_bytes_acked,
 169                                sp->pathmtu);
 170                 }
 171                 printl("\n");
 172         }
 173
 174         jprobe_return();
 175         return 0;
 176 }
 177
 178 static struct jprobe sctp_recv_probe = {
 179         .kp     = {
 180                 .symbol_name = "sctp_sf_eat_sack_6_2",
 181         },
 182         .entry  = jsctp_sf_eat_sack,
 183 };
 184
 185 static __init int sctpprobe_init(void)
 186 {
 187         int ret = -ENOMEM;
 188
 189         /* Warning: if the function signature of sctp_sf_eat_sack_6_2,
 190          * has been changed, you also have to change the signature of
 191          * jsctp_sf_eat_sack, otherwise you end up right here!
 192          */
 193         BUILD_BUG_ON(__same_type(sctp_sf_eat_sack_6_2,
 194                                  jsctp_sf_eat_sack) == 0);
 195
 196         init_waitqueue_head(&sctpw.wait);
 197         spin_lock_init(&sctpw.lock);
 198         if (kfifo_alloc(&sctpw.fifo, bufsize, GFP_KERNEL))
 199                 return ret;
 200
 201         if (!proc_create(procname, S_IRUSR, init_net.proc_net,
 202                          &sctpprobe_fops))
 203                 goto free_kfifo;
 204
 205         ret = register_jprobe(&sctp_recv_probe);
 206         if (ret)
 207                 goto remove_proc;
 208
 209         pr_info("probe registered (port=%d/fwmark=%u) bufsize=%u\n",
 210                 port, fwmark, bufsize);
 211         return 0;
 212
 213 remove_proc:
 214         remove_proc_entry(procname, init_net.proc_net);
 215 free_kfifo:
 216         kfifo_free(&sctpw.fifo);
 217         return ret;
 218 }
 219
 220 static __exit void sctpprobe_exit(void)
 221 {
 222         kfifo_free(&sctpw.fifo);
 223         remove_proc_entry(procname, init_net.proc_net);
 224         unregister_jprobe(&sctp_recv_probe);
 225 }
 226
 227 module_init(sctpprobe_init);
 228 module_exit(sctpprobe_exit);