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// 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 void shutdown_umh(void)
{
struct umd_info *info = &bpfilter_ops.info;
struct pid *tgid = info->tgid;
if (tgid) {
kill_pid(tgid, SIGKILL, 1);
wait_event(tgid->wait_pidfd, thread_group_exited(tgid));
bpfilter_umh_cleanup(info);
}
}
static void __stop_umh(void)
{
if (IS_ENABLED(CONFIG_INET))
shutdown_umh();
}
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 = (uintptr_t)optval;
req.len = optlen;
if (!bpfilter_ops.info.tgid)
goto out;
pos = 0;
n = kernel_write(bpfilter_ops.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(bpfilter_ops.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:
return ret;
}
static int start_umh(void)
{
int err;
/* fork usermode process */
err = fork_usermode_driver(&bpfilter_ops.info);
if (err)
return err;
pr_info("Loaded bpfilter_umh pid %d\n", pid_nr(bpfilter_ops.info.tgid));
/* health check that usermode process started correctly */
if (__bpfilter_process_sockopt(NULL, 0, NULL, 0, 0) != 0) {
shutdown_umh();
return -EFAULT;
}
return 0;
}
static int __init load_umh(void)
{
int err;
err = umd_load_blob(&bpfilter_ops.info,
&bpfilter_umh_start,
&bpfilter_umh_end - &bpfilter_umh_start);
if (err)
return err;
mutex_lock(&bpfilter_ops.lock);
err = start_umh();
if (!err && IS_ENABLED(CONFIG_INET)) {
bpfilter_ops.sockopt = &__bpfilter_process_sockopt;
bpfilter_ops.start = &start_umh;
}
mutex_unlock(&bpfilter_ops.lock);
if (err)
umd_unload_blob(&bpfilter_ops.info);
return err;
}
static void __exit fini_umh(void)
{
mutex_lock(&bpfilter_ops.lock);
if (IS_ENABLED(CONFIG_INET)) {
shutdown_umh();
bpfilter_ops.start = NULL;
bpfilter_ops.sockopt = NULL;
}
mutex_unlock(&bpfilter_ops.lock);
umd_unload_blob(&bpfilter_ops.info);
}
module_init(load_umh);
module_exit(fini_umh);
MODULE_LICENSE("GPL");
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