From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e35.co.us.ibm.com (e35.co.us.ibm.com [32.97.110.153]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "e35.co.us.ibm.com", Issuer "Equifax" (verified OK)) by ozlabs.org (Postfix) with ESMTPS id 3D6E9DE00B for ; Thu, 19 Jun 2008 07:16:07 +1000 (EST) Received: from d03relay02.boulder.ibm.com (d03relay02.boulder.ibm.com [9.17.195.227]) by e35.co.us.ibm.com (8.13.8/8.13.8) with ESMTP id m5ILFvZ5018295 for ; Wed, 18 Jun 2008 17:15:57 -0400 Received: from d03av04.boulder.ibm.com (d03av04.boulder.ibm.com [9.17.195.170]) by d03relay02.boulder.ibm.com (8.13.8/8.13.8/NCO v9.0) with ESMTP id m5ILFvV6168852 for ; Wed, 18 Jun 2008 15:15:57 -0600 Received: from d03av04.boulder.ibm.com (loopback [127.0.0.1]) by d03av04.boulder.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id m5ILFuqe025974 for ; Wed, 18 Jun 2008 15:15:56 -0600 Date: Wed, 18 Jun 2008 14:15:55 -0700 From: Eric B Munson To: linuxppc-dev@ozlabs.org Subject: [RFC PATCH V2] Keep 3 high personality bytes across exec Message-ID: <20080618211555.GA21865@us.ibm.com> References: <20080618060651.GA8251@us.ibm.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="dDRMvlgZJXvWKvBx" In-Reply-To: <20080618060651.GA8251@us.ibm.com> Cc: linux-kernel@vger.kernel.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , --dDRMvlgZJXvWKvBx Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Currently when a 32 bit process is exec'd on a powerpc 64 bit host the value in the top three bytes of the personality is clobbered. This patch adds a check in the SET_PERSONALITY macro that will carry all the values in the top three bytes across the exec. These three bytes currently carry flags to disable address randomisation, limit the address space, force zeroing of an mmapped page, etc. Should an application set any of these bits they will be maintained and honoured on homogeneous environment but discarded and ignored on a heterogeneous environment. So if an application requires all mmapped pages to be initial= ised to zero and a wrapper is used to setup the personality and exec the target, these flags will remain set on an all 32 or all 64 bit envrionment, but they will be lost in the exec on a mixed 32/64 bit environment. Losing these bi= ts means that the same application would behave differently in different environments. Tested on a POWER5+ machine with 64bit kernel and a mixed 64/32 bit user space. Signed-off-by: Eric B Munson --- V2 Changes from V1: Updated changelog with a better description of why this change is useful Based on 2.6.26-rc6 include/asm-powerpc/elf.h | 3 ++- include/linux/personality.h | 6 ++++++ 2 files changed, 8 insertions(+), 1 deletions(-) diff --git a/include/asm-powerpc/elf.h b/include/asm-powerpc/elf.h index 9080d85..2f11a0e 100644 --- a/include/asm-powerpc/elf.h +++ b/include/asm-powerpc/elf.h @@ -257,7 +257,8 @@ do { \ else \ clear_thread_flag(TIF_ABI_PENDING); \ if (personality(current->personality) !=3D PER_LINUX32) \ - set_personality(PER_LINUX); \ + set_personality(PER_LINUX | \ + (current->personality & PER_INHERIT)); \ } while (0) /* * An executable for which elf_read_implies_exec() returns TRUE will diff --git a/include/linux/personality.h b/include/linux/personality.h index a84e9ff..362eb90 100644 --- a/include/linux/personality.h +++ b/include/linux/personality.h @@ -36,6 +36,12 @@ enum { ADDR_LIMIT_3GB =3D 0x8000000, }; =20 +/* Mask for the above personality values */ +#define PER_INHERIT (ADDR_NO_RANDOMIZE|FDPIC_FUNCPTRS|MMAP_PAGE_ZERO| \ + ADDR_COMPAT_LAYOUT|READ_IMPLIES_EXEC|ADDR_LIMIT_32BIT| \ + SHORT_INODE|WHOLE_SECONDS|STICKY_TIMEOUTS| \ + ADDR_LIMIT_3GB) + /* * Security-relevant compatibility flags that must be * cleared upon setuid or setgid exec: --dDRMvlgZJXvWKvBx Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (GNU/Linux) iD8DBQFIWXsLsnv9E83jkzoRAmvvAKD2suHEuv/a0lIssNGonxgQjIixAQCg7GIc bRVSwh+iGam+oxJVs+GpgFQ= =zVLk -----END PGP SIGNATURE----- --dDRMvlgZJXvWKvBx--