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
  34 #include "dccp.h"
  35 #include "ccid.h"
  36 #include "ccids/ccid3.h"
  37
  38 static int port;
  39
  40 static int bufsize = 64 * 1024;
  41
  42 static const char procname[] = "dccpprobe";
  43
  44 struct {
  45         struct kfifo      *fifo;
  46         spinlock_t        lock;
  47         wait_queue_head_t wait;
  48         struct timeval    tstart;
  49 } dccpw;
  50
  51 static void printl(const char *fmt, ...)
  52 {
  53         va_list args;
  54         int len;
  55         struct timeval now;
  56         char tbuf[256];
  57
  58         va_start(args, fmt);
  59         do_gettimeofday(&now);
  60
  61         now.tv_sec -= dccpw.tstart.tv_sec;
  62         now.tv_usec -= dccpw.tstart.tv_usec;
  63         if (now.tv_usec < 0) {
  64                 --now.tv_sec;
  65                 now.tv_usec += 1000000;
  66         }
  67
  68         len = sprintf(tbuf, "%lu.%06lu ",
  69                       (unsigned long) now.tv_sec,
  70                       (unsigned long) now.tv_usec);
  71         len += vscnprintf(tbuf+len, sizeof(tbuf)-len, fmt, args);
  72         va_end(args);
  73
  74         kfifo_put(dccpw.fifo, tbuf, len);
  75         wake_up(&dccpw.wait);
  76 }
  77
  78 static int jdccp_sendmsg(struct kiocb *iocb, struct sock *sk,
  79                          struct msghdr *msg, size_t size)
  80 {
  81         const struct dccp_minisock *dmsk = dccp_msk(sk);
  82         const struct inet_sock *inet = inet_sk(sk);
  83         const struct ccid3_hc_tx_sock *hctx;
  84
  85         if (dmsk->dccpms_tx_ccid == DCCPC_CCID3)
  86                 hctx = ccid3_hc_tx_sk(sk);
  87         else
  88                 hctx = NULL;
  89
  90         if (port == 0 || ntohs(inet->dport) == port ||
  91             ntohs(inet->sport) == port) {
  92                 if (hctx)
  93                         printl("%d.%d.%d.%d:%u %d.%d.%d.%d:%u %d %d %d %d %d\n",
  94                            NIPQUAD(inet->saddr), ntohs(inet->sport),
  95                            NIPQUAD(inet->daddr), ntohs(inet->dport), size,
  96                            hctx->ccid3hctx_s, hctx->ccid3hctx_rtt,
  97                            hctx->ccid3hctx_p, hctx->ccid3hctx_t_ipi);
  98                 else
  99                         printl("%d.%d.%d.%d:%u %d.%d.%d.%d:%u %d\n",
 100                            NIPQUAD(inet->saddr), ntohs(inet->sport),
 101                            NIPQUAD(inet->daddr), ntohs(inet->dport), size);
 102         }
 103
 104         jprobe_return();
 105         return 0;
 106 }
 107
 108 static struct jprobe dccp_send_probe = {
 109         .kp     = { .addr = (kprobe_opcode_t *)&dccp_sendmsg, },
 110         .entry  = (kprobe_opcode_t *)&jdccp_sendmsg,
 111 };
 112
 113 static int dccpprobe_open(struct inode *inode, struct file *file)
 114 {
 115         kfifo_reset(dccpw.fifo);
 116         do_gettimeofday(&dccpw.tstart);
 117         return 0;
 118 }
 119
 120 static ssize_t dccpprobe_read(struct file *file, char __user *buf,
 121                               size_t len, loff_t *ppos)
 122 {
 123         int error = 0, cnt = 0;
 124         unsigned char *tbuf;
 125
 126         if (!buf || len < 0)
 127                 return -EINVAL;
 128
 129         if (len == 0)
 130                 return 0;
 131
 132         tbuf = vmalloc(len);
 133         if (!tbuf)
 134                 return -ENOMEM;
 135
 136         error = wait_event_interruptible(dccpw.wait,
 137                                          __kfifo_len(dccpw.fifo) != 0);
 138         if (error)
 139                 goto out_free;
 140
 141         cnt = kfifo_get(dccpw.fifo, tbuf, len);
 142         error = copy_to_user(buf, tbuf, cnt);
 143
 144 out_free:
 145         vfree(tbuf);
 146
 147         return error ? error : cnt;
 148 }
 149
 150 static struct file_operations dccpprobe_fops = {
 151         .owner   = THIS_MODULE,
 152         .open    = dccpprobe_open,
 153         .read    = dccpprobe_read,
 154 };
 155
 156 static __init int dccpprobe_init(void)
 157 {
 158         int ret = -ENOMEM;
 159
 160         init_waitqueue_head(&dccpw.wait);
 161         spin_lock_init(&dccpw.lock);
 162         dccpw.fifo = kfifo_alloc(bufsize, GFP_KERNEL, &dccpw.lock);
 163         if (IS_ERR(dccpw.fifo))
 164                 return PTR_ERR(dccpw.fifo);
 165
 166         if (!proc_net_fops_create(procname, S_IRUSR, &dccpprobe_fops))
 167                 goto err0;
 168
 169         ret = register_jprobe(&dccp_send_probe);
 170         if (ret)
 171                 goto err1;
 172
 173         pr_info("DCCP watch registered (port=%d)\n", port);
 174         return 0;
 175 err1:
 176         proc_net_remove(procname);
 177 err0:
 178         kfifo_free(dccpw.fifo);
 179         return ret;
 180 }
 181 module_init(dccpprobe_init);
 182
 183 static __exit void dccpprobe_exit(void)
 184 {
 185         kfifo_free(dccpw.fifo);
 186         proc_net_remove(procname);
 187         unregister_jprobe(&dccp_send_probe);
 188
 189 }
 190 module_exit(dccpprobe_exit);
 191
 192 MODULE_PARM_DESC(port, "Port to match (0=all)");
 193 module_param(port, int, 0);
 194
 195 MODULE_PARM_DESC(bufsize, "Log buffer size (default 64k)");
 196 module_param(bufsize, int, 0);
 197
 198 MODULE_AUTHOR("Ian McDonald <ian.mcdonald@jandi.co.nz>");
 199 MODULE_DESCRIPTION("DCCP snooper");
 200 MODULE_LICENSE("GPL");