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 <net/net_namespace.h>
  34
  35#include "dccp.h"
  36#include "ccid.h"
  37#include "ccids/ccid3.h"
  38
  39static int port;
  40
  41static int bufsize = 64 * 1024;
  42
  43static const char procname[] = "dccpprobe";
  44
  45static struct {
  46        struct kfifo      *fifo;
  47        spinlock_t        lock;
  48        wait_queue_head_t wait;
  49        struct timespec   tstart;
  50} dccpw;
  51
  52static 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_put(dccpw.fifo, tbuf, len);
  71        wake_up(&dccpw.wait);
  72}
  73
  74static 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 *hctx = NULL;
  79
  80        if (ccid_get_current_tx_ccid(dccp_sk(sk)) == DCCPC_CCID3)
  81                hctx = ccid3_hc_tx_sk(sk);
  82
  83        if (port == 0 || ntohs(inet->dport) == port ||
  84            ntohs(inet->sport) == port) {
  85                if (hctx)
  86                        printl("%pI4:%u %pI4:%u %d %d %d %d %u "
  87                               "%llu %llu %d\n",
  88                               &inet->saddr, ntohs(inet->sport),
  89                               &inet->daddr, ntohs(inet->dport), size,
  90                               hctx->ccid3hctx_s, hctx->ccid3hctx_rtt,
  91                               hctx->ccid3hctx_p, hctx->ccid3hctx_x_calc,
  92                               hctx->ccid3hctx_x_recv >> 6,
  93                               hctx->ccid3hctx_x >> 6, hctx->ccid3hctx_t_ipi);
  94                else
  95                        printl("%pI4:%u %pI4:%u %d\n",
  96                               &inet->saddr, ntohs(inet->sport),
  97                               &inet->daddr, ntohs(inet->dport), 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_get(dccpw.fifo, tbuf, len);
 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};
 153
 154static __init int dccpprobe_init(void)
 155{
 156        int ret = -ENOMEM;
 157
 158        init_waitqueue_head(&dccpw.wait);
 159        spin_lock_init(&dccpw.lock);
 160        dccpw.fifo = kfifo_alloc(bufsize, GFP_KERNEL, &dccpw.lock);
 161        if (IS_ERR(dccpw.fifo))
 162                return PTR_ERR(dccpw.fifo);
 163
 164        if (!proc_net_fops_create(&init_net, procname, S_IRUSR, &dccpprobe_fops))
 165                goto err0;
 166
 167        ret = register_jprobe(&dccp_send_probe);
 168        if (ret)
 169                goto err1;
 170
 171        pr_info("DCCP watch registered (port=%d)\n", port);
 172        return 0;
 173err1:
 174        proc_net_remove(&init_net, procname);
 175err0:
 176        kfifo_free(dccpw.fifo);
 177        return ret;
 178}
 179module_init(dccpprobe_init);
 180
 181static __exit void dccpprobe_exit(void)
 182{
 183        kfifo_free(dccpw.fifo);
 184        proc_net_remove(&init_net, procname);
 185        unregister_jprobe(&dccp_send_probe);
 186
 187}
 188module_exit(dccpprobe_exit);
 189
 190MODULE_PARM_DESC(port, "Port to match (0=all)");
 191module_param(port, int, 0);
 192
 193MODULE_PARM_DESC(bufsize, "Log buffer size (default 64k)");
 194module_param(bufsize, int, 0);
 195
 196MODULE_AUTHOR("Ian McDonald <ian.mcdonald@jandi.co.nz>");
 197MODULE_DESCRIPTION("DCCP snooper");
 198MODULE_LICENSE("GPL");
 199