[PATCH 3/3] startup: mount ps only on policy FS_EXTERNAL

[Fabian Pflug <f.pflug@pengutronix.de>]

Without the SCONFIG_FS_EXTERNAL, the bus of the driver for pstore will
not load, resulting in a missing driver for pstore and an error during
bootup.
Only mount the /pstore if FS_EXTERNAL is allowed by the security policy.

Signed-off-by: Fabian Pflug <f.pflug@pengutronix.de>
---
v2:
remove the umount
add unregister_handler
 common/startup.c | 26 ++++++++++++++++++++++++--
 1 file changed, 24 insertions(+), 2 deletions(-)

diff --git a/common/startup.c b/common/startup.c
index 4313435f05..7cf7088ad6 100644
--- a/common/startup.c
+++ b/common/startup.c
@@ -55,6 +55,22 @@ extern exitcall_t __barebox_exitcalls_start[], __barebox_exitcalls_end[];
 enum system_states barebox_system_state;
 
 #if defined CONFIG_FS_RAMFS && defined CONFIG_FS_DEVFS
+static struct sconfig_notifier_block sconfig_notifier;
+
+static void mount_pstore(struct sconfig_notifier_block *nb,
+			 enum security_config_option opt, bool allowed)
+{
+	if (allowed) {
+		mkdir("/pstore", 0);
+		mount("none", "pstore", "/pstore", NULL);
+		sconfig_unregister_handler(&sconfig_notifier);
+	}
+	/*
+	* no need to umount, since the permission is only needed for mounting,
+	* not for accessing the content.
+	*/
+}
+
 static int mount_root(void)
 {
 	mount("none", "ramfs", "/", NULL);
@@ -69,8 +85,14 @@ static int mount_root(void)
 	}
 
 	if (IS_ENABLED(CONFIG_FS_PSTORE)) {
-		mkdir("/pstore", 0);
-		mount("none", "pstore", "/pstore", NULL);
+		if (IS_ALLOWED(SCONFIG_FS_EXTERNAL)) {
+			mkdir("/pstore", 0);
+			mount("none", "pstore", "/pstore", NULL);
+		} else {
+			sconfig_register_handler_filtered(&sconfig_notifier,
+							  mount_pstore,
+							  SCONFIG_FS_EXTERNAL);
+		}
 	}
 
 	if (IS_ENABLED(CONFIG_9P_FS))
-- 
2.47.3