[mirror_ubuntu-focal-kernel.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 = pid_task(find_vpid(info->pid), PIDTYPE_PID);
	if (tsk)
		force_sig(SIGKILL, 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)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 */
	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, 0, 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;
d2ba09c1 AS	26	tsk = pid_task(find_vpid(info->pid), PIDTYPE_PID);
	27	if (tsk)
	28	force_sig(SIGKILL, tsk);
	29	fput(info->pipe_to_umh);
	30	fput(info->pipe_from_umh);
66e58e0e	31	info->pid = 0;
d2ba09c1 AS	32	}
	33
	34	static void __stop_umh(void)
	35	{
66e58e0e	36	if (IS_ENABLED(CONFIG_INET)) {
d2ba09c1 AS	37	bpfilter_process_sockopt = NULL;
	38	shutdown_umh(&info);
	39	}
	40	}
	41
	42	static void stop_umh(void)
	43	{
	44	mutex_lock(&bpfilter_lock);
	45	__stop_umh();
	46	mutex_unlock(&bpfilter_lock);
	47	}
	48
	49	static int __bpfilter_process_sockopt(struct sock *sk, int optname,
	50	char __user *optval,
	51	unsigned int optlen, bool is_set)
	52	{
	53	struct mbox_request req;
	54	struct mbox_reply reply;
	55	loff_t pos;
	56	ssize_t n;
66e58e0e	57	int ret = -EFAULT;
d2ba09c1 AS	58
	59	req.is_set = is_set;
	60	req.pid = current->pid;
	61	req.cmd = optname;
	62	req.addr = (long)optval;
	63	req.len = optlen;
	64	mutex_lock(&bpfilter_lock);
66e58e0e AS	65	if (!info.pid)
66e58e0e AS	66	goto out;
d2ba09c1 AS	67	n = __kernel_write(info.pipe_to_umh, &req, sizeof(req), &pos);
	68	if (n != sizeof(req)) {
	69	pr_err("write fail %zd\n", n);
	70	__stop_umh();
	71	ret = -EFAULT;
	72	goto out;
	73	}
	74	pos = 0;
	75	n = kernel_read(info.pipe_from_umh, &reply, sizeof(reply), &pos);
	76	if (n != sizeof(reply)) {
	77	pr_err("read fail %zd\n", n);
	78	__stop_umh();
	79	ret = -EFAULT;
	80	goto out;
	81	}
	82	ret = reply.status;
	83	out:
	84	mutex_unlock(&bpfilter_lock);
	85	return ret;
	86	}
	87
	88	static int __init load_umh(void)
	89	{
	90	int err;
	91
	92	/* fork usermode process */
8e75887d MY	93	err = fork_usermode_blob(&bpfilter_umh_start,
	94	&bpfilter_umh_end - &bpfilter_umh_start,
	95	&info);
d2ba09c1 AS	96	if (err)
	97	return err;
	98	pr_info("Loaded bpfilter_umh pid %d\n", info.pid);
	99
	100	/* health check that usermode process started correctly */
	101	if (__bpfilter_process_sockopt(NULL, 0, 0, 0, 0) != 0) {
	102	stop_umh();
	103	return -EFAULT;
	104	}
d71dbdaa AB	105	if (IS_ENABLED(CONFIG_INET))
	106	bpfilter_process_sockopt = &__bpfilter_process_sockopt;
	107
d2ba09c1 AS	108	return 0;
	109	}
	110
	111	static void __exit fini_umh(void)
	112	{
	113	stop_umh();
	114	}
	115	module_init(load_umh);
	116	module_exit(fini_umh);
	117	MODULE_LICENSE("GPL");