Commit 61fbf593 authored by Taehee Yoo's avatar Taehee Yoo Committed by David S. Miller
Browse files

net: bpfilter: restart bpfilter_umh when error occurred 



The bpfilter_umh will be stopped via __stop_umh() when the bpfilter
error occurred.
The bpfilter_umh() couldn't start again because there is no restart
routine.

The section of the bpfilter_umh_{start/end} is no longer .init.rodata
because these area should be reused in the restart routine. hence
the section name is changed to .bpfilter_umh.

The bpfilter_ops->start() is restart callback. it will be called when
bpfilter_umh is stopped.
The stop bit means bpfilter_umh is stopped. this bit is set by both
start and stop routine.

Before this patch,
Test commands:
   $ iptables -vnL
   $ kill -9 <pid of bpfilter_umh>
   $ iptables -vnL
   [  480.045136] bpfilter: write fail -32
   $ iptables -vnL

All iptables commands will fail.

After this patch,
Test commands:
   $ iptables -vnL
   $ kill -9 <pid of bpfilter_umh>
   $ iptables -vnL
   $ iptables -vnL

Now, all iptables commands will work.

Fixes: d2ba09c1 ("net: add skeleton of bpfilter kernel module")
Signed-off-by: default avatarTaehee Yoo <ap420073@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 5b4cb650

include/linux/bpfilter.h

+2 −0
Original line number Diff line number Diff line
@@ -15,6 +15,8 @@ struct bpfilter_umh_ops { 
	int (*sockopt)(struct sock *sk, int optname,

		       char __user *optval,

		       unsigned int optlen, bool is_set);

	int (*start)(void);

	bool stop;

};

extern struct bpfilter_umh_ops bpfilter_ops;

#endif

net/bpfilter/bpfilter_kern.c

+27 −10
Original line number Diff line number Diff line
@@ -16,13 +16,14 @@ extern char bpfilter_umh_end; 
/* since ip_getsockopt() can run in parallel, serialize access to umh */

static DEFINE_MUTEX(bpfilter_lock);



static void shutdown_umh(struct umh_info *info)

static void shutdown_umh(void)

{

	struct task_struct *tsk;



	if (!info->pid)

	if (bpfilter_ops.stop)

		return;

	tsk = get_pid_task(find_vpid(info->pid), PIDTYPE_PID);



	tsk = get_pid_task(find_vpid(bpfilter_ops.info.pid), PIDTYPE_PID);

	if (tsk) {

		force_sig(SIGKILL, tsk);

		put_task_struct(tsk);
@@ -31,10 +32,8 @@ static void shutdown_umh(struct umh_info *info) 


static void __stop_umh(void)

{

	if (IS_ENABLED(CONFIG_INET)) {

		bpfilter_ops.sockopt = NULL;

		shutdown_umh(&bpfilter_ops.info);

	}

	if (IS_ENABLED(CONFIG_INET))

		shutdown_umh();

}



static void stop_umh(void)
@@ -85,7 +84,7 @@ out: 
	return ret;

}



static int __init load_umh(void)

static int start_umh(void)

{

	int err;
@@ -95,6 +94,7 @@ static int __init load_umh(void) 
				 &bpfilter_ops.info);

	if (err)

		return err;

	bpfilter_ops.stop = false;

	pr_info("Loaded bpfilter_umh pid %d\n", bpfilter_ops.info.pid);



	/* health check that usermode process started correctly */
@@ -102,14 +102,31 @@ static int __init load_umh(void) 
		stop_umh();

		return -EFAULT;

	}

	if (IS_ENABLED(CONFIG_INET))

		bpfilter_ops.sockopt = &__bpfilter_process_sockopt;



	return 0;

}



static int __init load_umh(void)

{

	int err;



	if (!bpfilter_ops.stop)

		return -EFAULT;

	err = start_umh();

	if (!err && IS_ENABLED(CONFIG_INET)) {

		bpfilter_ops.sockopt = &__bpfilter_process_sockopt;

		bpfilter_ops.start = &start_umh;

	}



	return err;

}



static void __exit fini_umh(void)

{

	if (IS_ENABLED(CONFIG_INET)) {

		bpfilter_ops.start = NULL;

		bpfilter_ops.sockopt = NULL;

	}

	stop_umh();

}

module_init(load_umh);

net/bpfilter/bpfilter_umh_blob.S

+1 −1
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0 */

	.section .init.rodata, "a"

	.section .bpfilter_umh, "a"

	.global bpfilter_umh_start

bpfilter_umh_start:

	.incbin "net/bpfilter/bpfilter_umh"

net/ipv4/bpfilter/sockopt.c

+10 −1
Original line number Diff line number Diff line
@@ -14,6 +14,7 @@ EXPORT_SYMBOL_GPL(bpfilter_ops); 


static void bpfilter_umh_cleanup(struct umh_info *info)

{

	bpfilter_ops.stop = true;

	fput(info->pipe_to_umh);

	fput(info->pipe_from_umh);

	info->pid = 0;
@@ -23,14 +24,21 @@ static int bpfilter_mbox_request(struct sock *sk, int optname, 
				 char __user *optval,

				 unsigned int optlen, bool is_set)

{

	int err;



	if (!bpfilter_ops.sockopt) {

		int err = request_module("bpfilter");

		err = request_module("bpfilter");



		if (err)

			return err;

		if (!bpfilter_ops.sockopt)

			return -ECHILD;

	}

	if (bpfilter_ops.stop) {

		err = bpfilter_ops.start();

		if (err)

			return err;

	}

	return bpfilter_ops.sockopt(sk, optname, optval, optlen, is_set);

}
@@ -53,6 +61,7 @@ int bpfilter_ip_get_sockopt(struct sock *sk, int optname, char __user *optval, 


static int __init bpfilter_sockopt_init(void)

{

	bpfilter_ops.stop = true;

	bpfilter_ops.info.cmdline = "bpfilter_umh";

	bpfilter_ops.info.cleanup = &bpfilter_umh_cleanup;

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