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