linux.git/fs/super.c, branch v5.3

Unbreak mount_capable()

2019-07-31T16:22:32+00:00

In "consolidate the capability checks in sget_{fc,userns}())" the
wrong argument had been passed to mount_capable() by sget_fc().
That mistake had been further obscured later, when switching
mount_capable() to fs_context has moved the calculation of
bogus argument from sget_fc() to mount_capable() itself.  It
should've been fc->user_ns all along.

Screwed-up-by: Al Viro 
Reported-by: Christian Brauner 
Tested-by: Christian Brauner 
Reviewed-by: David Howells 
Signed-off-by: Al Viro

convenience helper: get_tree_single()

2019-07-05T02:01:58+00:00

counterpart of mount_single(); switch fusectl to it

Signed-off-by: Al Viro

convenience helper get_tree_nodev()

2019-07-05T02:01:58+00:00

counterpart of mount_nodev().  Switch hugetlb and pseudo to it.

Signed-off-by: Al Viro

vfs: Kill sget_userns()

2019-05-25T22:06:17+00:00

Kill sget_userns(), folding it into sget() as that's the only remaining
user.

Signed-off-by: David Howells 
cc: linux-fsdevel@vger.kernel.org

vfs: Provide sb->s_iflags settings in fs_context struct

2019-05-25T22:00:03+00:00

Provide a field in the fs_context struct through which bits in the
sb->s_iflags superblock field can be set.

Signed-off-by: David Howells 
cc: linux-fsdevel@vger.kernel.org

move mount_capable() further out

2019-05-25T22:00:02+00:00

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

move mount_capable() calls to vfs_get_tree()

2019-05-25T22:00:01+00:00

sget_fc() is called only from ->get_tree() instances and
the only instance not calling it is legacy_get_tree(),
which calls mount_capable() directly.

In all sget_fc() callers the checks could be moved to the
very beginning of ->get_tree() - ->user_ns is not changed
in between.  So lifting the checks to the only caller of
->get_tree() is OK.

Signed-off-by: Al Viro

switch mount_capable() to fs_context

2019-05-25T21:59:59+00:00

	now both callers of mount_capable() have access to fs_context;
the only difference is that for sget_fc() we have the possibility
of fc->global being true, while for legacy_get_tree() it's guaranteed
to be impossible.  Unify to more generic variant...

Signed-off-by: Al Viro

move the capability checks from sget_userns() to legacy_get_tree()

2019-05-25T21:59:58+00:00

1) all call chains leading to sget_userns() pass through ->mount()
instances.
2) none of ->mount() instances is ever called directly - the only
call site is legacy_get_tree()
3) all remaining ->mount() instances end up calling sget_userns()

IOW, we might as well do the capability checks just before calling
->mount().  As for the arguments passed to mount_capable(),
in case of call chains to sget_userns() going through sget(),
we either don't call mount_capable() at all, or pass current_user_ns()
to it.  The call chains going through mount_pseudo_xattr() don't
call mount_capable() at all (SB_KERNMOUNT in flags on those).

That could've been split into smaller steps (lifting the checks
into sget(), then callers of sget(), then all the way to the
entries of every ->mount() out there, then to the sole caller),
but that would be too much churn for little benefit...

Signed-off-by: Al Viro

vfs: Kill mount_ns()

2019-05-25T21:59:57+00:00

Kill mount_ns() as it has been replaced by vfs_get_super() in the new mount
API.

Signed-off-by: David Howells 
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Al Viro