Date: Wed, 22 Nov 2017 15:27:11 -0700 From: Kurt Seifried <kseifrie@...hat.com> To: oss-security@...ts.openwall.com Cc: Bram Moolenaar <Bram@...lenaar.net> Subject: Re: Re: Security risk of server side text editing ... Can you post a summary of the issues, it sounds like more than one CVE will be needed, thanks. -Kurt > On Nov 22, 2017, at 15:17, Solar Designer <solar@...nwall.com> wrote: > >> On Fri, Nov 17, 2017 at 11:35:15AM +0100, Bram Moolenaar wrote: >> Please check out patch 8.0.1300. > > Thanks. Personally, I don't have much to add. This continues to do > what I find are weird and wrong things, so any implementation issues are > secondary to that. I suppose you have some rationale for preserving the > old behavior of propagating the edited file's permissions onto related > temporary files, but I'm unaware of good reasons for that. > > If it's about users' collaboration, then I don't see a good reason for > other users in the group, even if they could access the original file > via group permissions, to also have access to recovery and backup files. > > As to the patch itself, aside from it propagating the possibly unsafe > permissions on purpose (I mean unsafe such as in Hanno's original > example, but also applying to backup files), it's also risky in > temporarily setting umask to 0. On some systems, this could mean libc > or the kernel creating files with unsafe permissions if anything goes > very wrong during this time - e.g., a coredump. Checking st_ino is OK > as a hardening measure, but might not always be sufficient: inode number > reuse is possible if the original file could have been deleted. > I suppose st_dev is not checked because of the use of O_NOFOLLOW, but I > guess Vim can be built on systems without working O_NOFOLLOW as well? > > In case anyone wants to review the patch for real, I've attached it to > this message, and here it is on GitHub (for expanding of the context): > > https://github.com/vim/vim/commit/cd142e3369db8888163a511dbe9907bcd138829c > > Alexander > <8.0.1300>
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