Re: [PATCH v9] fs: clear file privilege bits when mmap writing

On Fri, Jan 27, 2017 at 7:47 PM, Andy Lutomirski [off-list ref] wrote:

On Wed, May 25, 2016 at 2:49 PM, Al Viro [off-list ref] wrote:

quoted

On Wed, May 25, 2016 at 02:36:57PM -0700, Kees Cook wrote:

quoted

Hm, this didn't end up getting picked up. (This jumped out at me again
because i_mutex just vanished...)

Al, what's the right way to update the locking in this patch?

->i_mutex is dealt with just by using lock_inode(inode)/unlock_inode(inode);
I hadn't looked at the rest of the locking in there.

Ping?

If this is too messy, I'm wondering if we could get away with a much
simpler approach: clear the suid and sgid bits when the file is opened
for write.

I think that'll break something, but I don't have any actual examples.
Regardless, I'd still like to see this hole fixed...

-Kees

-- 
Kees Cook
Pixel Security

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