path: root/include/linux/fs.h
diff options
authorEric W. Biederman <ebiederm@xmission.com>2013-03-30 19:57:41 -0700
committerEric W. Biederman <ebiederm@xmission.com>2013-08-26 19:17:03 -0700
commite51db73532955dc5eaba4235e62b74b460709d5b (patch)
treeef2b73dd5e04d5b97a0bb10e8a163811ce9a3845 /include/linux/fs.h
parent4ce5d2b1a8fde84c0eebe70652cf28b9beda6b4e (diff)
userns: Better restrictions on when proc and sysfs can be mounted
Rely on the fact that another flavor of the filesystem is already mounted and do not rely on state in the user namespace. Verify that the mounted filesystem is not covered in any significant way. I would love to verify that the previously mounted filesystem has no mounts on top but there are at least the directories /proc/sys/fs/binfmt_misc and /sys/fs/cgroup/ that exist explicitly for other filesystems to mount on top of. Refactor the test into a function named fs_fully_visible and call that function from the mount routines of proc and sysfs. This makes this test local to the filesystems involved and the results current of when the mounts take place, removing a weird threading of the user namespace, the mount namespace and the filesystems themselves. Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Diffstat (limited to 'include/linux/fs.h')
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 981874773e85..3050c620f062 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1897,6 +1897,7 @@ extern int vfs_ustat(dev_t, struct kstatfs *);
extern int freeze_super(struct super_block *super);
extern int thaw_super(struct super_block *super);
extern bool our_mnt(struct vfsmount *mnt);
+extern bool fs_fully_visible(struct file_system_type *);
extern int current_umask(void);