net/dccp/probe.c

   1 /*
   2  * dccp_probe - Observe the DCCP 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 DCCP from Stephen Hemminger's code
   8  * Copyright (C) 2006, Ian McDonald <ian.mcdonald@jandi.co.nz>
   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/dccp.h>
  29 #include <linux/proc_fs.h>
  30 #include <linux/module.h>
  31 #include <linux/kfifo.h>
  32 #include <linux/vmalloc.h>
  33 #include <linux/gfp.h>
  34 #include <net/net_namespace.h>
  35
  36 #include "dccp.h"
  37 #include "ccid.h"
  38 #include "ccids/ccid3.h"
  39
  40 static int port;
  41
  42 static int bufsize = 64 * 1024;
  43
  44 static const char procname[] = "dccpprobe";
  45
  46 static struct {
  47         struct kfifo      fifo;
  48         spinlock_t        lock;
  49         wait_queue_head_t wait;
  50         struct timespec   tstart;
  51 } dccpw;
  52
  53 static void printl(const char *fmt, ...)
  54 {
  55         va_list args;
  56         int len;
  57         struct timespec now;
  58         char tbuf[256];
  59
  60         va_start(args, fmt);
  61         getnstimeofday(&now);
  62
  63         now = timespec_sub(now, dccpw.tstart);
  64
  65         len = sprintf(tbuf, "%lu.%06lu ",
  66                       (unsigned long) now.tv_sec,
  67                       (unsigned long) now.tv_nsec / NSEC_PER_USEC);
  68         len += vscnprintf(tbuf+len, sizeof(tbuf)-len, fmt, args);
  69         va_end(args);
  70
  71         kfifo_in_locked(&dccpw.fifo, tbuf, len, &dccpw.lock);
  72         wake_up(&dccpw.wait);
  73 }
  74
  75 static int jdccp_sendmsg(struct kiocb *iocb, struct sock *sk,
  76                          struct msghdr *msg, size_t size)
  77 {
  78         const struct inet_sock *inet = inet_sk(sk);
  79         struct ccid3_hc_tx_sock *hc = NULL;
  80
  81         if (ccid_get_current_tx_ccid(dccp_sk(sk)) == DCCPC_CCID3)
  82                 hc = ccid3_hc_tx_sk(sk);
  83
  84         if (port == 0 || ntohs(inet->inet_dport) == port ||
  85             ntohs(inet->inet_sport) == port) {
  86                 if (hc)
  87                         printl("%pI4:%u %pI4:%u %d %d %d %d %u %llu %llu %d\n",
  88                                &inet->inet_saddr, ntohs(inet->inet_sport),
  89                                &inet->inet_daddr, ntohs(inet->inet_dport), size,
  90                                hc->tx_s, hc->tx_rtt, hc->tx_p,
  91                                hc->tx_x_calc, hc->tx_x_recv >> 6,
  92                                hc->tx_x >> 6, hc->tx_t_ipi);
  93                 else
  94                         printl("%pI4:%u %pI4:%u %d\n",
  95                                &inet->inet_saddr, ntohs(inet->inet_sport),
  96                                &inet->inet_daddr, ntohs(inet->inet_dport),
  97                                size);
  98         }
  99
 100         jprobe_return();
 101         return 0;
 102 }
 103
 104 static struct jprobe dccp_send_probe = {
 105         .kp     = {
 106                 .symbol_name = "dccp_sendmsg",
 107         },
 108         .entry  = jdccp_sendmsg,
 109 };
 110
 111 static int dccpprobe_open(struct inode *inode, struct file *file)
 112 {
 113         kfifo_reset(&dccpw.fifo);
 114         getnstimeofday(&dccpw.tstart);
 115         return 0;
 116 }
 117
 118 static ssize_t dccpprobe_read(struct file *file, char __user *buf,
 119                               size_t len, loff_t *ppos)
 120 {
 121         int error = 0, cnt = 0;
 122         unsigned char *tbuf;
 123
 124         if (!buf)
 125                 return -EINVAL;
 126
 127         if (len == 0)
 128                 return 0;
 129
 130         tbuf = vmalloc(len);
 131         if (!tbuf)
 132                 return -ENOMEM;
 133
 134         error = wait_event_interruptible(dccpw.wait,
 135                                          kfifo_len(&dccpw.fifo) != 0);
 136         if (error)
 137                 goto out_free;
 138
 139         cnt = kfifo_out_locked(&dccpw.fifo, tbuf, len, &dccpw.lock);
 140         error = copy_to_user(buf, tbuf, cnt) ? -EFAULT : 0;
 141
 142 out_free:
 143         vfree(tbuf);
 144
 145         return error ? error : cnt;
 146 }
 147
 148 static const struct file_operations dccpprobe_fops = {
 149         .owner   = THIS_MODULE,
 150         .open    = dccpprobe_open,
 151         .read    = dccpprobe_read,
 152 };
 153
 154 static __init int dccpprobe_init(void)
 155 {
 156         int ret = -ENOMEM;
 157
 158         init_waitqueue_head(&dccpw.wait);
 159         spin_lock_init(&dccpw.lock);
 160         if (kfifo_alloc(&dccpw.fifo, bufsize, GFP_KERNEL))
 161                 return ret;
 162         if (!proc_net_fops_create(&init_net, procname, S_IRUSR, &dccpprobe_fops))
 163                 goto err0;
 164
 165         try_then_request_module((ret = register_jprobe(&dccp_send_probe)) == 0,
 166                                 "dccp");
 167         if (ret)
 168                 goto err1;
 169
 170         pr_info("DCCP watch registered (port=%d)\n", port);
 171         return 0;
 172 err1:
 173         proc_net_remove(&init_net, procname);
 174 err0:
 175         kfifo_free(&dccpw.fifo);
 176         return ret;
 177 }
 178 module_init(dccpprobe_init);
 179
 180 static __exit void dccpprobe_exit(void)
 181 {
 182         kfifo_free(&dccpw.fifo);
 183         proc_net_remove(&init_net, procname);
 184         unregister_jprobe(&dccp_send_probe);
 185
 186 }
 187 module_exit(dccpprobe_exit);
 188
 189 MODULE_PARM_DESC(port, "Port to match (0=all)");
 190 module_param(port, int, 0);
 191
 192 MODULE_PARM_DESC(bufsize, "Log buffer size (default 64k)");
 193 module_param(bufsize, int, 0);
 194
 195 MODULE_AUTHOR("Ian McDonald <ian.mcdonald@jandi.co.nz>");
 196 MODULE_DESCRIPTION("DCCP snooper");
 197 MODULE_LICENSE("GPL");