Date: Sat, 4 Oct 2014 19:36:33 +0300 From: Konstantin Belousov <kostikbel@gmail.com> To: "Bjoern A. Zeeb" <bz@FreeBSD.org> Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org, Mateusz Guzik <mjg@FreeBSD.org> Subject: Re: svn commit: r272505 - in head/sys: kern sys Message-ID: <20141004163633.GT26076@kib.kiev.ua> In-Reply-To: <42180557-0119-4597-9492-662E1671A840@FreeBSD.org> References: <201410040808.s9488uAI099166@svn.freebsd.org> <42180557-0119-4597-9492-662E1671A840@FreeBSD.org>
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On Sat, Oct 04, 2014 at 02:21:54PM +0000, Bjoern A. Zeeb wrote: > > On 04 Oct 2014, at 08:08 , Mateusz Guzik <mjg@FreeBSD.org> wrote: > > > Author: mjg > > Date: Sat Oct 4 08:08:56 2014 > > New Revision: 272505 > > URL: https://svnweb.freebsd.org/changeset/base/272505 > > > > Log: > > Plug capability races. > > > > fp and appropriate capability lookups were not atomic, which could result in > > improper capabilities being checked. > > > > This could result either in protection bypass or in a spurious ENOTCAPABLE. > > > > Make fp + capability check atomic with the help of sequence counters. > > > > Reviewed by: kib > > MFC after: 3 weeks > > > > Modified: > > head/sys/kern/kern_descrip.c > > head/sys/sys/filedesc.h > > ? > > > This file is included from user space. There is no opt_capsicum.h there. > Including an opt_* in the header file seems wrong in a lot of ways usually. I think that easiest, and probably the most correct, fix is to include the fde_seq member unconditionally. > > I tried to add a bandaid for the moment with r272523 which (to be honest) makes it worse. > > This needs a better fix. Hm, I do see inclusion of sys/filedesc.h in the usermode programs, most worrying is libprocstat. But, there is nothing useful for usermode in the header, except possibly for the code with inspects KVA. > > > I also wonder why the (conditional) fde_seq ended up at the beginning of the structure rather than the end? > Why not ?
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