From: Cheng Yang <chengyang@xxxxxxxxxx>
The proc_parse_options() call from proc_mount() runs only once at boot
time. So on any later mount attempt, any mount options are ignored
because ->s_root is already initialized.
As a consequence, "mount -o <options>" will ignore the options. The
only way to change mount options is "mount -o remount,<options>".
To fix this, parse the mount options unconditionally.
Signed-off-by: Cheng Yang <chengyang@xxxxxxxxxx>
---
fs/proc/inode.c | 4 ----
fs/proc/root.c | 3 +++
2 files changed, 3 insertions(+), 4 deletions(-)
diff --git a/fs/proc/inode.c b/fs/proc/inode.c
index 5792f9e..ec509d1 100644
--- a/fs/proc/inode.c
+++ b/fs/proc/inode.c
@@ -493,13 +493,9 @@ struct inode *proc_get_inode(struct super_block *sb, struct proc_dir_entry *de)
int proc_fill_super(struct super_block *s, void *data, int silent)
{
- struct pid_namespace *ns = get_pid_ns(s->s_fs_info);
struct inode *root_inode;
int ret;
- if (!proc_parse_options(data, ns))
- return -EINVAL;
-
/* User space would break if executables or devices appear on proc */
s->s_iflags |= SB_I_USERNS_VISIBLE | SB_I_NOEXEC | SB_I_NODEV;
s->s_flags |= SB_NODIRATIME | SB_NOSUID | SB_NOEXEC;
diff --git a/fs/proc/root.c b/fs/proc/root.c
index f4b1a9d..f5f3bf3 100644
--- a/fs/proc/root.c
+++ b/fs/proc/root.c
@@ -98,6 +98,9 @@ static struct dentry *proc_mount(struct file_system_type *fs_type,
ns = task_active_pid_ns(current);
}
+ if (!proc_parse_options(data, ns))
+ return ERR_PTR(-EINVAL);
+
return mount_ns(fs_type, flags, data, ns, ns->user_ns, proc_fill_super);
}
--
1.9.1
