| Message ID | 153913023835.32295.13962696655740190941.stgit@magnolia (mailing list archive) |
|---|---|
| Headers | show |
| Series | fs: fixes for serious clone/dedupe problems | expand |
On Tue, Oct 09, 2018 at 05:10:38PM -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. > > So, here's the whole giant pile of patches[1] that fix all the problems. > The patch "generic: test reflink side effects" recently sent to fstests > exercises the fixes in this series. Tests are in [2]. Can you rebase this on the for-next branch on the xfs tree which already contains some of the initial fixes in the series and a couple of other reflink/dedupe data corruption fixes? I'm planning on pushing them to Greg tomorrow, so you'll have to do this soon anyway.... Cheers, Dave.
On Wed, Oct 10, 2018 at 12:02:08PM +1100, Dave Chinner wrote: > On Tue, Oct 09, 2018 at 05:10:38PM -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. > > > > So, here's the whole giant pile of patches[1] that fix all the problems. > > The patch "generic: test reflink side effects" recently sent to fstests > > exercises the fixes in this series. Tests are in [2]. > > Can you rebase this on the for-next branch on the xfs tree which > already contains some of the initial fixes in the series and a > couple of other reflink/dedupe data corruption fixes? I'm planning > on pushing them to Greg tomorrow, so you'll have to do this soon > anyway.... <nod> I was planning to do that tomorrow, but figured I might as well scrape for review comments in the mean time. --D > Cheers, > > Dave. > -- > Dave Chinner > david@fromorbit.com