ovl: simplify permission checking

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The fact that we always do permission checking on the overlay inode and
clear MAY_WRITE for checking access to the lower inode allows cruft to be
removed from ovl_permission().

1) "default_permissions" option effectively did generic_permission() on the
overlay inode with i_mode, i_uid and i_gid updated from underlying
filesystem.  This is what we do by default now.  It did the update using
vfs_getattr() but that's only needed if the underlying filesystem can
change (which is not allowed).  We may later introduce a "paranoia_mode"
that verifies that mode/uid/gid are not changed.

2) splitting out the IS_RDONLY() check from inode_permission() also becomes
unnecessary once we remove the MAY_WRITE from the lower inode check.

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

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This commit is contained in:

Miklos Szeredi 2016-07-29 12:05:23 +02:00

parent 754f8cb72b

commit 9c630ebefe

3 changed files with 1 additions and 53 deletions

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46

fs/overlayfs/inode.c

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1

fs/overlayfs/overlayfs.h

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7

fs/overlayfs/super.c

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