kernel.git/fs/overlayfs/inode.c, branch linux-4.8.y

ovl: fix get_acl() on tmpfs

2016-11-10T15:38:51Z

commit b93d4a0eb308d4400b84c8b24c1b80e09a9497d0 upstream. tmpfs doesn't have ->get_acl() because it only uses cached acls. This fixes the acl tests in pjdfstest when tmpfs is used as the upper layer of the overlay. Reported-by: Amir Goldstein Signed-off-by: Miklos Szeredi Fixes: 39a25b2b3762 ("ovl: define ->get_acl() for overlay inodes") Signed-off-by: Greg Kroah-Hartman

ovl: listxattr: use strnlen()

2016-09-01T09:12:00Z

Be defensive about what underlying fs provides us in the returned xattr list buffer. If it's not properly null terminated, bail out with a warning insead of BUG. Signed-off-by: Miklos Szeredi Cc:

ovl: Switch to generic_getxattr

2016-09-01T09:12:00Z

Now that overlayfs has xattr handlers for iop->{set,remove}xattr, use those same handlers for iop->getxattr as well. Signed-off-by: Andreas Gruenbacher Signed-off-by: Miklos Szeredi

ovl: Switch to generic_removexattr

2016-09-01T09:12:00Z

Commit d837a49bd57f ("ovl: fix POSIX ACL setting") switches from iop->setxattr from ovl_setxattr to generic_setxattr, so switch from ovl_removexattr to generic_removexattr as well. As far as permission checking goes, the same rules should apply in either case. While doing that, rename ovl_setxattr to ovl_xattr_set to indicate that this is not an iop->setxattr implementation and remove the unused inode argument. Move ovl_other_xattr_set above ovl_own_xattr_set so that they match the order of handlers in ovl_xattr_handlers. Signed-off-by: Andreas Gruenbacher Fixes: d837a49bd57f ("ovl: fix POSIX ACL setting") Signed-off-by: Miklos Szeredi

ovl: Fix OVL_XATTR_PREFIX

2016-09-01T09:11:59Z

Make sure ovl_own_xattr_handler only matches attribute names starting with "overlay.", not "overlayXXX". Signed-off-by: Andreas Gruenbacher Fixes: d837a49bd57f ("ovl: fix POSIX ACL setting") Signed-off-by: Miklos Szeredi

ovl: don't cache acl on overlay layer

2016-09-01T09:11:59Z

Some operations (setxattr/chmod) can make the cached acl stale. We either need to clear overlay's acl cache for the affected inode or prevent acl caching on the overlay altogether. Preventing caching has the following advantages: - no double caching, less memory used - overlay cache doesn't go stale when fs clears it's own cache Possible disadvantage is performance loss. If that becomes a problem get_acl() can be optimized for overlayfs. This patch disables caching by pre setting i_*acl to a value that - has bit 0 set, so is_uncached_acl() will return true - is not equal to ACL_NOT_CACHED, so get_acl() will not overwrite it The constant -3 was chosen for this purpose. Fixes: 39a25b2b3762 ("ovl: define ->get_acl() for overlay inodes") Signed-off-by: Miklos Szeredi

ovl: use cached acl on underlying layer

2016-09-01T09:11:59Z

Instead of calling ->get_acl() directly, use get_acl() to get the cached value. We will have the acl cached on the underlying inode anyway, because we do permission checking on the both the overlay and the underlying fs. So, since we already have double caching, this improves performance without any cost. Signed-off-by: Miklos Szeredi

ovl: don't copy up opaqueness

2016-08-08T13:08:49Z

When a copy up of a directory occurs which has the opaque xattr set, the xattr remains in the upper directory. The immediate behavior with overlayfs is that the upper directory is not treated as opaque, however after a remount the opaque flag is used and upper directory is treated as opaque. This causes files created in the lower layer to be hidden when using multiple lower directories. Fix by not copying up the opaque flag. To reproduce: ----8<---------8<---------8<---------8<---------8<---------8<---- mkdir -p l/d/s u v w mnt mount -t overlay overlay -olowerdir=l,upperdir=u,workdir=w mnt rm -rf mnt/d/ mkdir -p mnt/d/n umount mnt mount -t overlay overlay -olowerdir=u:l,upperdir=v,workdir=w mnt touch mnt/d/foo umount mnt mount -t overlay overlay -olowerdir=u:l,upperdir=v,workdir=w mnt ls mnt/d ----8<---------8<---------8<---------8<---------8<---------8<---- output should be: "foo n" Reported-by: Derek McGowan Link: https://bugzilla.kernel.org/show_bug.cgi?id=151291 Signed-off-by: Miklos Szeredi Cc:

ovl: append MAY_READ when diluting write checks

2016-07-29T10:05:24Z

Right now we remove MAY_WRITE/MAY_APPEND bits from mask if realfile is on lower/. This is done as files on lower will never be written and will be copied up. But to copy up a file, mounter should have MAY_READ permission otherwise copy up will fail. So set MAY_READ in mask when MAY_WRITE is reset. Dan Walsh noticed this when he did access(lowerfile, W_OK) and it returned True (context mounts) but when he tried to actually write to file, it failed as mounter did not have permission on lower file. [SzM] don't set MAY_READ if only MAY_APPEND is set without MAY_WRITE; this won't trigger a copy-up. Reported-by: Dan Walsh Signed-off-by: Vivek Goyal Signed-off-by: Miklos Szeredi

ovl: dilute permission checks on lower only if not special file

2016-07-29T10:05:24Z

Right now if file is on lower/, we remove MAY_WRITE/MAY_APPEND bits from mask as lower/ will never be written and file will be copied up. But this is not true for special files. These files are not copied up and are opened in place. So don't dilute the checks for these types of files. Reported-by: Dan Walsh Signed-off-by: Vivek Goyal Signed-off-by: Miklos Szeredi