linux/net/dccp/probe.c
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   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
  40static int port;
  41
  42static int bufsize = 64 * 1024;
  43
  44static const char procname[] = "dccpprobe";
  45
  46static struct {
  47        struct kfifo      fifo;
  48        spinlock_t        lock;
  49        wait_queue_head_t wait;
  50        struct timespec   tstart;
  51} dccpw;
  52
  53static 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
  75static 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
 104static struct jprobe dccp_send_probe = {
 105        .kp     = {
 106                .symbol_name = "dccp_sendmsg",
 107        },
 108        .entry  = jdccp_sendmsg,
 109};
 110
 111static int dccpprobe_open(struct inode *inode, struct file *file)
 112{
 113        kfifo_reset(&dccpw.fifo);
 114        getnstimeofday(&dccpw.tstart);
 115        return 0;
 116}
 117
 118static 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
 142out_free:
 143        vfree(tbuf);
 144
 145        return error ? error : cnt;
 146}
 147
 148static const struct file_operations dccpprobe_fops = {
 149        .owner   = THIS_MODULE,
 150        .open    = dccpprobe_open,
 151        .read    = dccpprobe_read,
 152        .llseek  = noop_llseek,
 153};
 154
 155static __init int setup_jprobe(void)
 156{
 157        int ret = register_jprobe(&dccp_send_probe);
 158
 159        if (ret) {
 160                request_module("dccp");
 161                ret = register_jprobe(&dccp_send_probe);
 162        }
 163        return ret;
 164}
 165
 166static __init int dccpprobe_init(void)
 167{
 168        int ret = -ENOMEM;
 169
 170        init_waitqueue_head(&dccpw.wait);
 171        spin_lock_init(&dccpw.lock);
 172        if (kfifo_alloc(&dccpw.fifo, bufsize, GFP_KERNEL))
 173                return ret;
 174        if (!proc_create(procname, S_IRUSR, init_net.proc_net, &dccpprobe_fops))
 175                goto err0;
 176
 177        ret = setup_jprobe();
 178        if (ret)
 179                goto err1;
 180
 181        pr_info("DCCP watch registered (port=%d)\n", port);
 182        return 0;
 183err1:
 184        remove_proc_entry(procname, init_net.proc_net);
 185err0:
 186        kfifo_free(&dccpw.fifo);
 187        return ret;
 188}
 189module_init(dccpprobe_init);
 190
 191static __exit void dccpprobe_exit(void)
 192{
 193        kfifo_free(&dccpw.fifo);
 194        remove_proc_entry(procname, init_net.proc_net);
 195        unregister_jprobe(&dccp_send_probe);
 196
 197}
 198module_exit(dccpprobe_exit);
 199
 200MODULE_PARM_DESC(port, "Port to match (0=all)");
 201module_param(port, int, 0);
 202
 203MODULE_PARM_DESC(bufsize, "Log buffer size (default 64k)");
 204module_param(bufsize, int, 0);
 205
 206MODULE_AUTHOR("Ian McDonald <ian.mcdonald@jandi.co.nz>");
 207MODULE_DESCRIPTION("DCCP snooper");
 208MODULE_LICENSE("GPL");
 209
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