4 files changed, 40 insertions, 12 deletions

diff --git a/include/linux/bpfilter.h b/include/linux/bpfilter.h
index 70ffeed280e9..8ebcbdd70bdc 100644
--- a/include/linux/bpfilter.h
+++ b/include/linux/bpfilter.h
@@ -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
diff --git a/net/bpfilter/bpfilter_kern.c b/net/bpfilter/bpfilter_kern.c
index a68940b74c01..c0fcde910a7a 100644
--- a/net/bpfilter/bpfilter_kern.c
+++ b/net/bpfilter/bpfilter_kern.c
@@ -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);
diff --git a/net/bpfilter/bpfilter_umh_blob.S b/net/bpfilter/bpfilter_umh_blob.S
index 40311d10d2f2..7f1c521dcc2f 100644
--- a/net/bpfilter/bpfilter_umh_blob.S
+++ b/net/bpfilter/bpfilter_umh_blob.S
@@ -1,5 +1,5 @@
 /* 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"
diff --git a/net/ipv4/bpfilter/sockopt.c b/net/ipv4/bpfilter/sockopt.c
index c326cfbc0f62..de84ede4e765 100644
--- a/net/ipv4/bpfilter/sockopt.c
+++ b/net/ipv4/bpfilter/sockopt.c
@@ -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;