On Mon, Feb 12, 2018 at 03:32:36PM -0800, Kees Cook wrote:
On Mon, Feb 12, 2018 at 8:52 AM, Igor Stoppa [off-list ref] wrote:
quoted
This patch-set introduces the possibility of protecting memory that has
been allocated dynamically.
The memory is managed in pools: when a memory pool is turned into R/O,
all the memory that is part of it, will become R/O.
A R/O pool can be destroyed, to recover its memory, but it cannot be
turned back into R/W mode.
This is intentional. This feature is meant for data that doesn't need
further modifications after initialization.
This series came up in discussions with Dave Chinner (and Matthew
Wilcox, already part of the discussion, and others) at LCA. I wonder
if XFS would make a good initial user of this, as it could allocate
all the function pointers and other const information about a
superblock in pmalloc(), keeping it separate from the R/W portions?
Could other filesystems do similar things?
I wasn't cc'd on this patchset, (please use david at fromorbit.com for
future postings) so I can't really say anything about it right
now. My interest for XFS was that we have a fair amount of static
data in XFS that we set up at mount time and it never gets modified
after that. I'm not so worried about VFS level objects (that's a
much more complex issue) but there is a lot of low hanging fruit in
the XFS structures we could convert to write-once structures.
Cheers,
Dave.
--
Dave Chinner
dchinner at redhat.com
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