61fbf5933d
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: d2ba09c17a ("net: add skeleton of bpfilter kernel module")
Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
135 lines
2.7 KiB
C
135 lines
2.7 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/init.h>
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#include <linux/module.h>
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#include <linux/umh.h>
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#include <linux/bpfilter.h>
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#include <linux/sched.h>
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#include <linux/sched/signal.h>
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#include <linux/fs.h>
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#include <linux/file.h>
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#include "msgfmt.h"
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extern char bpfilter_umh_start;
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extern char bpfilter_umh_end;
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/* since ip_getsockopt() can run in parallel, serialize access to umh */
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static DEFINE_MUTEX(bpfilter_lock);
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static void shutdown_umh(void)
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{
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struct task_struct *tsk;
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if (bpfilter_ops.stop)
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return;
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tsk = get_pid_task(find_vpid(bpfilter_ops.info.pid), PIDTYPE_PID);
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if (tsk) {
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force_sig(SIGKILL, tsk);
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put_task_struct(tsk);
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}
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}
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static void __stop_umh(void)
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{
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if (IS_ENABLED(CONFIG_INET))
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shutdown_umh();
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}
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static void stop_umh(void)
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{
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mutex_lock(&bpfilter_lock);
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__stop_umh();
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mutex_unlock(&bpfilter_lock);
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}
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static int __bpfilter_process_sockopt(struct sock *sk, int optname,
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char __user *optval,
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unsigned int optlen, bool is_set)
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{
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struct mbox_request req;
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struct mbox_reply reply;
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loff_t pos;
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ssize_t n;
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int ret = -EFAULT;
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req.is_set = is_set;
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req.pid = current->pid;
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req.cmd = optname;
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req.addr = (long __force __user)optval;
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req.len = optlen;
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mutex_lock(&bpfilter_lock);
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if (!bpfilter_ops.info.pid)
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goto out;
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n = __kernel_write(bpfilter_ops.info.pipe_to_umh, &req, sizeof(req),
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&pos);
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if (n != sizeof(req)) {
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pr_err("write fail %zd\n", n);
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__stop_umh();
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ret = -EFAULT;
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goto out;
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}
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pos = 0;
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n = kernel_read(bpfilter_ops.info.pipe_from_umh, &reply, sizeof(reply),
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&pos);
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if (n != sizeof(reply)) {
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pr_err("read fail %zd\n", n);
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__stop_umh();
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ret = -EFAULT;
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goto out;
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}
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ret = reply.status;
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out:
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mutex_unlock(&bpfilter_lock);
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return ret;
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}
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static int start_umh(void)
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{
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int err;
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/* fork usermode process */
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err = fork_usermode_blob(&bpfilter_umh_start,
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&bpfilter_umh_end - &bpfilter_umh_start,
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&bpfilter_ops.info);
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if (err)
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return err;
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bpfilter_ops.stop = false;
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pr_info("Loaded bpfilter_umh pid %d\n", bpfilter_ops.info.pid);
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/* health check that usermode process started correctly */
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if (__bpfilter_process_sockopt(NULL, 0, NULL, 0, 0) != 0) {
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stop_umh();
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return -EFAULT;
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}
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return 0;
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}
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static int __init load_umh(void)
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{
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int err;
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if (!bpfilter_ops.stop)
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return -EFAULT;
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err = start_umh();
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if (!err && IS_ENABLED(CONFIG_INET)) {
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bpfilter_ops.sockopt = &__bpfilter_process_sockopt;
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bpfilter_ops.start = &start_umh;
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}
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return err;
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}
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static void __exit fini_umh(void)
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{
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if (IS_ENABLED(CONFIG_INET)) {
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bpfilter_ops.start = NULL;
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bpfilter_ops.sockopt = NULL;
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}
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stop_umh();
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}
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module_init(load_umh);
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module_exit(fini_umh);
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MODULE_LICENSE("GPL");
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