1. 09 May, 2016 37 commits
  2. 04 May, 2016 3 commits
    • Hector Marco-Gisbert's avatar
      x86/mm/32: Enable full randomization on i386 and X86_32 · 5c66bd4b
      Hector Marco-Gisbert authored
      commit 8b8addf8 upstream.
      
      Currently on i386 and on X86_64 when emulating X86_32 in legacy mode, only
      the stack and the executable are randomized but not other mmapped files
      (libraries, vDSO, etc.). This patch enables randomization for the
      libraries, vDSO and mmap requests on i386 and in X86_32 in legacy mode.
      
      By default on i386 there are 8 bits for the randomization of the libraries,
      vDSO and mmaps which only uses 1MB of VA.
      
      This patch preserves the original randomness, using 1MB of VA out of 3GB or
      4GB. We think that 1MB out of 3GB is not a big cost for having the ASLR.
      
      The first obvious security benefit is that all objects are randomized (not
      only the stack and the executable) in legacy mode which highly increases
      the ASLR effectiveness, otherwise the attackers may use these
      non-randomized areas. But also sensitive setuid/setgid applications are
      more secure because currently, attackers can disable the randomization of
      these applications by setting the ulimit stack to "unlimited". This is a
      very old and widely known trick to disable the ASLR in i386 which has been
      allowed for too long.
      
      Another trick used to disable the ASLR was to set the ADDR_NO_RANDOMIZE
      personality flag, but fortunately this doesn't work on setuid/setgid
      applications because there is security checks which clear Security-relevant
      flags.
      
      This patch always randomizes the mmap_legacy_base address, removing the
      possibility to disable the ASLR by setting the stack to "unlimited".
      Signed-off-by: default avatarHector Marco-Gisbert <hecmargi@upv.es>
      Acked-by: default avatarIsmael Ripoll Ripoll <iripoll@upv.es>
      Acked-by: default avatarKees Cook <keescook@chromium.org>
      Acked-by: default avatarArjan van de Ven <arjan@linux.intel.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: akpm@linux-foundation.org
      Cc: kees Cook <keescook@chromium.org>
      Link: http://lkml.kernel.org/r/1457639460-5242-1-git-send-email-hecmargi@upv.esSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
      Reference: CVE-2016-3672
      Signed-off-by: default avatarKamal Mostafa <kamal@canonical.com>
      5c66bd4b
    • Kees Cook's avatar
      mm: fold arch_randomize_brk into ARCH_HAS_ELF_RANDOMIZE · 350e988f
      Kees Cook authored
      commit 204db6ed upstream.
      
      The arch_randomize_brk() function is used on several architectures,
      even those that don't support ET_DYN ASLR. To avoid bulky extern/#define
      tricks, consolidate the support under CONFIG_ARCH_HAS_ELF_RANDOMIZE for
      the architectures that support it, while still handling CONFIG_COMPAT_BRK.
      Signed-off-by: default avatarKees Cook <keescook@chromium.org>
      Cc: Hector Marco-Gisbert <hecmargi@upv.es>
      Cc: Russell King <linux@arm.linux.org.uk>
      Reviewed-by: default avatarIngo Molnar <mingo@kernel.org>
      Cc: Catalin Marinas <catalin.marinas@arm.com>
      Cc: Will Deacon <will.deacon@arm.com>
      Cc: Ralf Baechle <ralf@linux-mips.org>
      Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
      Cc: Paul Mackerras <paulus@samba.org>
      Cc: Michael Ellerman <mpe@ellerman.id.au>
      Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
      Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
      Cc: Alexander Viro <viro@zeniv.linux.org.uk>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Andy Lutomirski <luto@amacapital.net>
      Cc: "David A. Long" <dave.long@linaro.org>
      Cc: Andrey Ryabinin <a.ryabinin@samsung.com>
      Cc: Arun Chandran <achandran@mvista.com>
      Cc: Yann Droneaud <ydroneaud@opteya.com>
      Cc: Min-Hua Chen <orca.chen@gmail.com>
      Cc: Paul Burton <paul.burton@imgtec.com>
      Cc: Alex Smith <alex@alex-smith.me.uk>
      Cc: Markos Chandras <markos.chandras@imgtec.com>
      Cc: Vineeth Vijayan <vvijayan@mvista.com>
      Cc: Jeff Bailey <jeffbailey@google.com>
      Cc: Michael Holzheu <holzheu@linux.vnet.ibm.com>
      Cc: Ben Hutchings <ben@decadent.org.uk>
      Cc: Behan Webster <behanw@converseincode.com>
      Cc: Ismael Ripoll <iripoll@upv.es>
      Cc: Jan-Simon Mller <dl9pf@gmx.de>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      Signed-off-by: default avatarKamal Mostafa <kamal@canonical.com>
      350e988f
    • Kees Cook's avatar
      mm: split ET_DYN ASLR from mmap ASLR · e19d0939
      Kees Cook authored
      commit d1fd836d upstream.
      
      This fixes the "offset2lib" weakness in ASLR for arm, arm64, mips,
      powerpc, and x86.  The problem is that if there is a leak of ASLR from
      the executable (ET_DYN), it means a leak of shared library offset as
      well (mmap), and vice versa.  Further details and a PoC of this attack
      is available here:
      
        http://cybersecurity.upv.es/attacks/offset2lib/offset2lib.html
      
      With this patch, a PIE linked executable (ET_DYN) has its own ASLR
      region:
      
        $ ./show_mmaps_pie
        54859ccd6000-54859ccd7000 r-xp  ...  /tmp/show_mmaps_pie
        54859ced6000-54859ced7000 r--p  ...  /tmp/show_mmaps_pie
        54859ced7000-54859ced8000 rw-p  ...  /tmp/show_mmaps_pie
        7f75be764000-7f75be91f000 r-xp  ...  /lib/x86_64-linux-gnu/libc.so.6
        7f75be91f000-7f75beb1f000 ---p  ...  /lib/x86_64-linux-gnu/libc.so.6
        7f75beb1f000-7f75beb23000 r--p  ...  /lib/x86_64-linux-gnu/libc.so.6
        7f75beb23000-7f75beb25000 rw-p  ...  /lib/x86_64-linux-gnu/libc.so.6
        7f75beb25000-7f75beb2a000 rw-p  ...
        7f75beb2a000-7f75beb4d000 r-xp  ...  /lib64/ld-linux-x86-64.so.2
        7f75bed45000-7f75bed46000 rw-p  ...
        7f75bed46000-7f75bed47000 r-xp  ...
        7f75bed47000-7f75bed4c000 rw-p  ...
        7f75bed4c000-7f75bed4d000 r--p  ...  /lib64/ld-linux-x86-64.so.2
        7f75bed4d000-7f75bed4e000 rw-p  ...  /lib64/ld-linux-x86-64.so.2
        7f75bed4e000-7f75bed4f000 rw-p  ...
        7fffb3741000-7fffb3762000 rw-p  ...  [stack]
        7fffb377b000-7fffb377d000 r--p  ...  [vvar]
        7fffb377d000-7fffb377f000 r-xp  ...  [vdso]
      
      The change is to add a call the newly created arch_mmap_rnd() into the
      ELF loader for handling ET_DYN ASLR in a separate region from mmap ASLR,
      as was already done on s390.  Removes CONFIG_BINFMT_ELF_RANDOMIZE_PIE,
      which is no longer needed.
      Signed-off-by: default avatarKees Cook <keescook@chromium.org>
      Reported-by: default avatarHector Marco-Gisbert <hecmargi@upv.es>
      Cc: Russell King <linux@arm.linux.org.uk>
      Reviewed-by: default avatarIngo Molnar <mingo@kernel.org>
      Cc: Catalin Marinas <catalin.marinas@arm.com>
      Cc: Will Deacon <will.deacon@arm.com>
      Cc: Ralf Baechle <ralf@linux-mips.org>
      Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
      Cc: Paul Mackerras <paulus@samba.org>
      Cc: Michael Ellerman <mpe@ellerman.id.au>
      Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
      Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
      Cc: Alexander Viro <viro@zeniv.linux.org.uk>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Andy Lutomirski <luto@amacapital.net>
      Cc: "David A. Long" <dave.long@linaro.org>
      Cc: Andrey Ryabinin <a.ryabinin@samsung.com>
      Cc: Arun Chandran <achandran@mvista.com>
      Cc: Yann Droneaud <ydroneaud@opteya.com>
      Cc: Min-Hua Chen <orca.chen@gmail.com>
      Cc: Paul Burton <paul.burton@imgtec.com>
      Cc: Alex Smith <alex@alex-smith.me.uk>
      Cc: Markos Chandras <markos.chandras@imgtec.com>
      Cc: Vineeth Vijayan <vvijayan@mvista.com>
      Cc: Jeff Bailey <jeffbailey@google.com>
      Cc: Michael Holzheu <holzheu@linux.vnet.ibm.com>
      Cc: Ben Hutchings <ben@decadent.org.uk>
      Cc: Behan Webster <behanw@converseincode.com>
      Cc: Ismael Ripoll <iripoll@upv.es>
      Cc: Jan-Simon Mller <dl9pf@gmx.de>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      Signed-off-by: default avatarKamal Mostafa <kamal@canonical.com>
      e19d0939