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authorAl Viro <viro@zeniv.linux.org.uk>2019-05-13 12:57:22 -0400
committerAl Viro <viro@zeniv.linux.org.uk>2019-05-25 18:00:02 -0400
commitc3aabf0780a506225b53bfe2b5177dd5dfec093d (patch)
tree95e0457725a49ae8849f4e17014de6871b78cac3 /fs/fsopen.c
parent059338aae33165179352a26b58d815801072c87d (diff)
downloadlinux-c3aabf0780a506225b53bfe2b5177dd5dfec093d.tar.gz
move mount_capable() further out
Call graph of vfs_get_tree():
	vfs_fsconfig_locked()	# neither kernmount, nor submount
	do_new_mount()		# neither kernmount, nor submount
	fc_mount()
		afs_mntpt_do_automount()	# submount
		mount_one_hugetlbfs()		# kernmount
		pid_ns_prepare_proc()		# kernmount
		mq_create_mount()		# kernmount
		vfs_kern_mount()
			simple_pin_fs()		# kernmount
			vfs_submount()		# submount
			kern_mount()		# kernmount
			init_mount_tree()
			btrfs_mount()
			nfs_do_root_mount()

	The first two need the check (unconditionally).
init_mount_tree() is setting rootfs up; any capability
checks make zero sense for that one.  And btrfs_mount()/
nfs_do_root_mount() have the checks already done in their
callers.

	IOW, we can shift mount_capable() handling into
the two callers - one in the normal case of mount(2),
another - in fsconfig(2) handling of FSCONFIG_CMD_CREATE.
I.e. the syscalls that set a new filesystem up.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs/fsopen.c')
-rw-r--r--fs/fsopen.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/fs/fsopen.c b/fs/fsopen.c
index c2891e933ef1..390172772f55 100644
--- a/fs/fsopen.c
+++ b/fs/fsopen.c
@@ -230,6 +230,8 @@ static int vfs_fsconfig_locked(struct fs_context *fc, int cmd,
 	case FSCONFIG_CMD_CREATE:
 		if (fc->phase != FS_CONTEXT_CREATE_PARAMS)
 			return -EBUSY;
+		if (!mount_capable(fc))
+			return -EPERM;
 		fc->phase = FS_CONTEXT_CREATING;
 		ret = vfs_get_tree(fc);
 		if (ret)