On Mon, Oct 22, 2018 at 01:21:12PM +1100, Dave Chinner wrote: > On Sun, Oct 21, 2018 at 09:15:03AM -0700, Darrick J. Wong wrote: > > Hi all, > > > > Dave, Eric, and I have been chasing a stale data exposure bug in the XFS > > reflink implementation, and tracked it down to reflink forgetting to do > > some of the file-extending activities that must happen for regular > > writes. > > > > We then started auditing the clone, dedupe, and copyfile code and > > realized that from a file contents perspective, clonerange isn't any > > different from a regular file write. Unfortunately, we also noticed > > that *unlike* a regular write, clonerange skips a ton of overflow > > checks, such as validating the ranges against s_maxbytes, MAX_NON_LFS, > > and RLIMIT_FSIZE. We also observed that cloning into a file did not > > strip security privileges (suid, capabilities) like a regular write > > would. I also noticed that xfs and ocfs2 need to dump the page cache > > before remapping blocks, not after. > > > > In fixing the range checking problems I also realized that both dedupe > > and copyfile tell userspace how much of the requested operation was > > acted upon. Since the range validation can shorten a clone request (or > > we can ENOSPC midway through), we might as well plumb the short > > operation reporting back through the VFS indirection code to userspace. > > I added a few more cleanups to the xfs code per reviewer suggestions. > > > > So, here's the whole giant pile of patches[1] that fix all the problems. > > This branch is against current upstream (4.19-rc8). The patch > > "generic: test reflink side effects" recently sent to fstests exercises > > the fixes in this series. Tests are in [2]. > > Ok, so now that all the patches (other than the ocfs2 bits) have been > reviewed, how do we want to merge this? I can take it through the > XFS tree given that there is a bit of XFS changes that needs to be > co-ordinated with it, or should it go through some other tree? Ok, this is a bit of a mess. the patches do not merge cleanly to a 4.19-rc1 base kernel because of all the changes to include/linux/fs.h that have hit the tree after this. There's also failures against Documentation/filesystems/fs.h IOWs, it's not going to get merged through the main XFS tree because I don't have the patience to resolve all the patch application failures, then when it comes to merge make sure all the merge failures end up being resolved correctly. So if I take it through the XFS tree, it will being a standalone branch based on 4.19-rc8 and won't hit linux-next until after the first XFS merge when I can rebase the for-next branch... Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx
