[DCCP]: Introduce dccp_probe

This adds DCCP probing shamelessly ripped off from TCP probes by Stephen
Hemminger.

I've put in here support for further CCID3 variables as well.
Andrea/Arnaldo might look to extend for CCID2.

Signed-off-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>

3 files changed, 216 insertions, 0 deletions

diff --git a/net/dccp/Kconfig b/net/dccp/Kconfig
index 859e3359fcda..e2a095d0fd80 100644
--- a/net/dccp/Kconfig
+++ b/net/dccp/Kconfig
@@ -40,6 +40,22 @@ config IP_DCCP_DEBUG
 
           Just say N.
 
+config NET_DCCPPROBE
+        tristate "DCCP connection probing"
+        depends on PROC_FS && KPROBES
+        ---help---
+        This module allows for capturing the changes to DCCP connection
+        state in response to incoming packets. It is used for debugging
+        DCCP congestion avoidance modules. If you don't understand
+        what was just said, you don't need it: say N.
+
+        Documentation on how to use the packet generator can be found
+        at http://linux-net.osdl.org/index.php/DccpProbe
+
+        To compile this code as a module, choose M here: the
+        module will be called dccp_probe.
+
+
 endmenu
 
 endmenu
diff --git a/net/dccp/Makefile b/net/dccp/Makefile
index 7696e219b05d..17ed99c46617 100644
--- a/net/dccp/Makefile
+++ b/net/dccp/Makefile
@@ -11,9 +11,11 @@ dccp_ipv4-y := ipv4.o
 dccp-$(CONFIG_IP_DCCP_ACKVEC) += ackvec.o
 
 obj-$(CONFIG_INET_DCCP_DIAG) += dccp_diag.o
+obj-$(CONFIG_NET_DCCPPROBE) += dccp_probe.o
 
 dccp-$(CONFIG_SYSCTL) += sysctl.o
 
 dccp_diag-y := diag.o
+dccp_probe-y := probe.o
 
 obj-y += ccids/
diff --git a/net/dccp/probe.c b/net/dccp/probe.c
new file mode 100644
index 000000000000..146496fce2e2
--- /dev/null
+++ b/net/dccp/probe.c
@@ -0,0 +1,198 @@
+/*
+ * dccp_probe - Observe the DCCP flow with kprobes.
+ *
+ * The idea for this came from Werner Almesberger's umlsim
+ * Copyright (C) 2004, Stephen Hemminger <shemminger@osdl.org>
+ *
+ * Modified for DCCP from Stephen Hemminger's code
+ * Copyright (C) 2006, Ian McDonald <ian.mcdonald@jandi.co.nz>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <linux/kernel.h>
+#include <linux/kprobes.h>
+#include <linux/socket.h>
+#include <linux/dccp.h>
+#include <linux/proc_fs.h>
+#include <linux/module.h>
+#include <linux/kfifo.h>
+#include <linux/vmalloc.h>
+
+#include "dccp.h"
+#include "ccid.h"
+#include "ccids/ccid3.h"
+
+static int port;
+
+static int bufsize = 64 * 1024;
+
+static const char procname[] = "dccpprobe";
+
+struct {
+        struct kfifo      *fifo;
+        spinlock_t        lock;
+        wait_queue_head_t wait;
+        struct timeval    tstart;
+} dccpw;
+
+static void printl(const char *fmt, ...)
+{
+        va_list args;
+        int len;
+        struct timeval now;
+        char tbuf[256];
+
+        va_start(args, fmt);
+        do_gettimeofday(&now);
+
+        now.tv_sec -= dccpw.tstart.tv_sec;
+        now.tv_usec -= dccpw.tstart.tv_usec;
+        if (now.tv_usec < 0) {
+                --now.tv_sec;
+                now.tv_usec += 1000000;
+        }
+
+        len = sprintf(tbuf, "%lu.%06lu ",
+                      (unsigned long) now.tv_sec,
+                      (unsigned long) now.tv_usec);
+        len += vscnprintf(tbuf+len, sizeof(tbuf)-len, fmt, args);
+        va_end(args);
+
+        kfifo_put(dccpw.fifo, tbuf, len);
+        wake_up(&dccpw.wait);
+}
+
+static int jdccp_sendmsg(struct kiocb *iocb, struct sock *sk,
+                         struct msghdr *msg, size_t size)
+{
+        const struct dccp_minisock *dmsk = dccp_msk(sk);
+        const struct inet_sock *inet = inet_sk(sk);
+        const struct ccid3_hc_tx_sock *hctx;
+
+        if (dmsk->dccpms_tx_ccid == DCCPC_CCID3)
+                hctx = ccid3_hc_tx_sk(sk);
+        else
+                hctx = NULL;
+
+        if (port == 0 || ntohs(inet->dport) == port ||
+            ntohs(inet->sport) == port) {
+                if (hctx)
+                        printl("%d.%d.%d.%d:%u %d.%d.%d.%d:%u %d %d %d %d %d\n",
+                           NIPQUAD(inet->saddr), ntohs(inet->sport),
+                           NIPQUAD(inet->daddr), ntohs(inet->dport), size,
+                           hctx->ccid3hctx_s, hctx->ccid3hctx_rtt,
+                           hctx->ccid3hctx_p, hctx->ccid3hctx_t_ipi);
+                else
+                        printl("%d.%d.%d.%d:%u %d.%d.%d.%d:%u %d\n",
+                           NIPQUAD(inet->saddr), ntohs(inet->sport),
+                           NIPQUAD(inet->daddr), ntohs(inet->dport), size);
+        }
+
+        jprobe_return();
+        return 0;
+}
+
+static struct jprobe dccp_send_probe = {
+        .kp     = { .addr = (kprobe_opcode_t *)&dccp_sendmsg, },
+        .entry  = (kprobe_opcode_t *)&jdccp_sendmsg,
+};
+
+static int dccpprobe_open(struct inode *inode, struct file *file)
+{
+        kfifo_reset(dccpw.fifo);
+        do_gettimeofday(&dccpw.tstart);
+        return 0;
+}
+
+static ssize_t dccpprobe_read(struct file *file, char __user *buf,
+                              size_t len, loff_t *ppos)
+{
+        int error = 0, cnt = 0;
+        unsigned char *tbuf;
+
+        if (!buf || len < 0)
+                return -EINVAL;
+
+        if (len == 0)
+                return 0;
+
+        tbuf = vmalloc(len);
+        if (!tbuf)
+                return -ENOMEM;
+
+        error = wait_event_interruptible(dccpw.wait,
+                                         __kfifo_len(dccpw.fifo) != 0);
+        if (error)
+                goto out_free;
+
+        cnt = kfifo_get(dccpw.fifo, tbuf, len);
+        error = copy_to_user(buf, tbuf, cnt);
+
+out_free:
+        vfree(tbuf);
+
+        return error ? error : cnt;
+}
+
+static struct file_operations dccpprobe_fops = {
+        .owner   = THIS_MODULE,
+        .open    = dccpprobe_open,
+        .read    = dccpprobe_read,
+};
+
+static __init int dccpprobe_init(void)
+{
+        int ret = -ENOMEM;
+
+        init_waitqueue_head(&dccpw.wait);
+        spin_lock_init(&dccpw.lock);
+        dccpw.fifo = kfifo_alloc(bufsize, GFP_KERNEL, &dccpw.lock);
+
+        if (!proc_net_fops_create(procname, S_IRUSR, &dccpprobe_fops))
+                goto err0;
+
+        ret = register_jprobe(&dccp_send_probe);
+        if (ret)
+                goto err1;
+
+        pr_info("DCCP watch registered (port=%d)\n", port);
+        return 0;
+err1:
+        proc_net_remove(procname);
+err0:
+        kfifo_free(dccpw.fifo);
+        return ret;
+}
+module_init(dccpprobe_init);
+
+static __exit void dccpprobe_exit(void)
+{
+        kfifo_free(dccpw.fifo);
+        proc_net_remove(procname);
+        unregister_jprobe(&dccp_send_probe);
+
+}
+module_exit(dccpprobe_exit);
+
+MODULE_PARM_DESC(port, "Port to match (0=all)");
+module_param(port, int, 0);
+
+MODULE_PARM_DESC(bufsize, "Log buffer size (default 64k)");
+module_param(bufsize, int, 0);
+
+MODULE_AUTHOR("Ian McDonald <ian.mcdonald@jandi.co.nz>");
+MODULE_DESCRIPTION("DCCP snooper");
+MODULE_LICENSE("GPL");