From: Vivek Goyal Date: Wed, 13 Jul 2016 15:00:14 +0000 (-0400) Subject: ovl: dilute permission checks on lower only if not special file X-Git-Tag: v4.8-rc1~107^2~7 X-Git-Url: http://git.cascardo.info/?p=cascardo%2Flinux.git;a=commitdiff_plain;h=e29841a0ab3d03e77313abd8fb4c16e80fb26e29 ovl: dilute permission checks on lower only if not special file 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 --- diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c index f7caf16f9bec..76cfe9d04e64 100644 --- a/fs/overlayfs/inode.c +++ b/fs/overlayfs/inode.c @@ -137,7 +137,7 @@ int ovl_permission(struct inode *inode, int mask) return err; old_cred = ovl_override_creds(inode->i_sb); - if (!is_upper) + if (!is_upper && !special_file(realinode->i_mode)) mask &= ~(MAY_WRITE | MAY_APPEND); err = inode_permission(realinode, mask); revert_creds(old_cred);