[linux-2.6-block.git] / net / bpfilter / bpfilter_kern.c

// SPDX-License-Identifier: GPL-2.0
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/init.h>
#include <linux/module.h>
#include <linux/umh.h>
#include <linux/bpfilter.h>
#include <linux/sched.h>
#include <linux/sched/signal.h>
#include <linux/fs.h>
#include <linux/file.h>
#include "msgfmt.h"

extern char bpfilter_umh_start;
extern char bpfilter_umh_end;

static struct umh_info info;
/* since ip_getsockopt() can run in parallel, serialize access to umh */
static DEFINE_MUTEX(bpfilter_lock);

static void shutdown_umh(struct umh_info *info)
{
	struct task_struct *tsk;

	if (!info->pid)
		return;
	tsk = get_pid_task(find_vpid(info->pid), PIDTYPE_PID);
	if (tsk) {
		force_sig(SIGKILL, tsk);
		put_task_struct(tsk);
	}
	fput(info->pipe_to_umh);
	fput(info->pipe_from_umh);
	info->pid = 0;
}

static void __stop_umh(void)
{
	if (IS_ENABLED(CONFIG_INET)) {
		bpfilter_process_sockopt = NULL;
		shutdown_umh(&info);
	}
}

static void stop_umh(void)
{
	mutex_lock(&bpfilter_lock);
	__stop_umh();
	mutex_unlock(&bpfilter_lock);
}

static int __bpfilter_process_sockopt(struct sock *sk, int optname,
				      char __user *optval,
				      unsigned int optlen, bool is_set)
{
	struct mbox_request req;
	struct mbox_reply reply;
	loff_t pos;
	ssize_t n;
	int ret = -EFAULT;

	req.is_set = is_set;
	req.pid = current->pid;
	req.cmd = optname;
	req.addr = (long __force __user)optval;
	req.len = optlen;
	mutex_lock(&bpfilter_lock);
	if (!info.pid)
		goto out;
	n = __kernel_write(info.pipe_to_umh, &req, sizeof(req), &pos);
	if (n != sizeof(req)) {
		pr_err("write fail %zd\n", n);
		__stop_umh();
		ret = -EFAULT;
		goto out;
	}
	pos = 0;
	n = kernel_read(info.pipe_from_umh, &reply, sizeof(reply), &pos);
	if (n != sizeof(reply)) {
		pr_err("read fail %zd\n", n);
		__stop_umh();
		ret = -EFAULT;
		goto out;
	}
	ret = reply.status;
out:
	mutex_unlock(&bpfilter_lock);
	return ret;
}

static int __init load_umh(void)
{
	int err;

	/* fork usermode process */
	info.cmdline = "bpfilter_umh";
	err = fork_usermode_blob(&bpfilter_umh_start,
				 &bpfilter_umh_end - &bpfilter_umh_start,
				 &info);
	if (err)
		return err;
	pr_info("Loaded bpfilter_umh pid %d\n", info.pid);

	/* health check that usermode process started correctly */
	if (__bpfilter_process_sockopt(NULL, 0, NULL, 0, 0) != 0) {
		stop_umh();
		return -EFAULT;
	}
	if (IS_ENABLED(CONFIG_INET))
		bpfilter_process_sockopt = &__bpfilter_process_sockopt;

	return 0;
}

static void __exit fini_umh(void)
{
	stop_umh();
}
module_init(load_umh);
module_exit(fini_umh);
MODULE_LICENSE("GPL");
Commit	Line	Data
d2ba09c1 AS	1	// SPDX-License-Identifier: GPL-2.0
	2	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
	3	#include <linux/init.h>
	4	#include <linux/module.h>
	5	#include <linux/umh.h>
	6	#include <linux/bpfilter.h>
	7	#include <linux/sched.h>
	8	#include <linux/sched/signal.h>
	9	#include <linux/fs.h>
	10	#include <linux/file.h>
	11	#include "msgfmt.h"
	12
8e75887d MY	13	extern char bpfilter_umh_start;
8e75887d MY	14	extern char bpfilter_umh_end;
d2ba09c1 AS	15
	16	static struct umh_info info;
	17	/* since ip_getsockopt() can run in parallel, serialize access to umh */
	18	static DEFINE_MUTEX(bpfilter_lock);
	19
	20	static void shutdown_umh(struct umh_info *info)
	21	{
	22	struct task_struct *tsk;
	23
66e58e0e AS	24	if (!info->pid)
66e58e0e AS	25	return;
84258438 TY	26	tsk = get_pid_task(find_vpid(info->pid), PIDTYPE_PID);
84258438 TY	27	if (tsk) {
d2ba09c1	28	force_sig(SIGKILL, tsk);
84258438 TY	29	put_task_struct(tsk);
84258438 TY	30	}
d2ba09c1 AS	31	fput(info->pipe_to_umh);
d2ba09c1 AS	32	fput(info->pipe_from_umh);
66e58e0e	33	info->pid = 0;
d2ba09c1 AS	34	}
	35
	36	static void __stop_umh(void)
	37	{
66e58e0e	38	if (IS_ENABLED(CONFIG_INET)) {
d2ba09c1 AS	39	bpfilter_process_sockopt = NULL;
	40	shutdown_umh(&info);
	41	}
	42	}
	43
	44	static void stop_umh(void)
	45	{
	46	mutex_lock(&bpfilter_lock);
	47	__stop_umh();
	48	mutex_unlock(&bpfilter_lock);
	49	}
	50
	51	static int __bpfilter_process_sockopt(struct sock *sk, int optname,
	52	char __user *optval,
	53	unsigned int optlen, bool is_set)
	54	{
	55	struct mbox_request req;
	56	struct mbox_reply reply;
	57	loff_t pos;
	58	ssize_t n;
66e58e0e	59	int ret = -EFAULT;
d2ba09c1 AS	60
	61	req.is_set = is_set;
	62	req.pid = current->pid;
	63	req.cmd = optname;
33aa8da1	64	req.addr = (long __force __user)optval;
d2ba09c1 AS	65	req.len = optlen;
d2ba09c1 AS	66	mutex_lock(&bpfilter_lock);
66e58e0e AS	67	if (!info.pid)
66e58e0e AS	68	goto out;
d2ba09c1 AS	69	n = __kernel_write(info.pipe_to_umh, &req, sizeof(req), &pos);
	70	if (n != sizeof(req)) {
	71	pr_err("write fail %zd\n", n);
	72	__stop_umh();
	73	ret = -EFAULT;
	74	goto out;
	75	}
	76	pos = 0;
	77	n = kernel_read(info.pipe_from_umh, &reply, sizeof(reply), &pos);
	78	if (n != sizeof(reply)) {
	79	pr_err("read fail %zd\n", n);
	80	__stop_umh();
	81	ret = -EFAULT;
	82	goto out;
	83	}
	84	ret = reply.status;
	85	out:
	86	mutex_unlock(&bpfilter_lock);
	87	return ret;
	88	}
	89
	90	static int __init load_umh(void)
	91	{
	92	int err;
	93
	94	/* fork usermode process */
4b78030b	95	info.cmdline = "bpfilter_umh";
8e75887d MY	96	err = fork_usermode_blob(&bpfilter_umh_start,
	97	&bpfilter_umh_end - &bpfilter_umh_start,
	98	&info);
d2ba09c1 AS	99	if (err)
	100	return err;
	101	pr_info("Loaded bpfilter_umh pid %d\n", info.pid);
	102
	103	/* health check that usermode process started correctly */
33aa8da1	104	if (__bpfilter_process_sockopt(NULL, 0, NULL, 0, 0) != 0) {
d2ba09c1 AS	105	stop_umh();
	106	return -EFAULT;
	107	}
d71dbdaa AB	108	if (IS_ENABLED(CONFIG_INET))
	109	bpfilter_process_sockopt = &__bpfilter_process_sockopt;
	110
d2ba09c1 AS	111	return 0;
	112	}
	113
	114	static void __exit fini_umh(void)
	115	{
	116	stop_umh();
	117	}
	118	module_init(load_umh);
	119	module_exit(fini_umh);
	120	MODULE_LICENSE("GPL");