linux-stable.git/fs/Kconfig.binfmt, branch linux-4.2.y

mm: split ET_DYN ASLR from mmap ASLR

2015-04-14T23:49:05+00:00

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: Kees Cook 
Reported-by: Hector Marco-Gisbert 
Cc: Russell King 
Reviewed-by: Ingo Molnar 
Cc: Catalin Marinas 
Cc: Will Deacon 
Cc: Ralf Baechle 
Cc: Benjamin Herrenschmidt 
Cc: Paul Mackerras 
Cc: Michael Ellerman 
Cc: Martin Schwidefsky 
Cc: Heiko Carstens 
Cc: Alexander Viro 
Cc: Oleg Nesterov 
Cc: Andy Lutomirski 
Cc: "David A. Long" 
Cc: Andrey Ryabinin 
Cc: Arun Chandran 
Cc: Yann Droneaud 
Cc: Min-Hua Chen 
Cc: Paul Burton 
Cc: Alex Smith 
Cc: Markos Chandras 
Cc: Vineeth Vijayan 
Cc: Jeff Bailey 
Cc: Michael Holzheu 
Cc: Ben Hutchings 
Cc: Behan Webster 
Cc: Ismael Ripoll 
Cc: Jan-Simon Mller 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

fs/binfmt_som: Drop kernel support for HP-UX SOM binaries

2015-02-17T15:29:36+00:00

The parisc arch has been the only user of HP-UX SOM binaries.

Support for HP-UX executables was never finished and since we now drop support
for the HP-UX compat layer anyway, it does not makes sense to keep the
BINFMT_SOM support.

Cc: linux-fsdevel@vger.kernel.org
Cc: linux-parisc@vger.kernel.org
Signed-off-by: Helge Deller

binfmt_elf: allow arch code to examine PT_LOPROC ... PT_HIPROC headers

2014-11-24T06:45:02+00:00

MIPS is introducing new variants of its O32 ABI which differ in their
handling of floating point, in order to enable a gradual transition
towards a world where mips32 binaries can take advantage of new hardware
features only available when configured for certain FP modes. In order
to do this ELF binaries are being augmented with a new section that
indicates, amongst other things, the FP mode requirements of the binary.
The presence & location of such a section is indicated by a program
header in the PT_LOPROC ... PT_HIPROC range.

In order to allow the MIPS architecture code to examine the program
header & section in question, pass all program headers in this range
to an architecture-specific arch_elf_pt_proc function. This function
may return an error if the header is deemed invalid or unsuitable for
the system, in which case that error will be returned from
load_elf_binary and upwards through the execve syscall.

A means is required for the architecture code to make a decision once
it is known that all such headers have been seen, but before it is too
late to return from an execve syscall. For this purpose the
arch_check_elf function is added, and called once, after all PT_LOPROC
to PT_HIPROC headers have been passed to arch_elf_pt_proc but before
the code which invoked execve has been lost. This enables the
architecture code to make a decision based upon all the headers present
in an ELF binary and its interpreter, as is required to forbid
conflicting FP ABI requirements between an ELF & its interpreter.

In order to allow data to be stored throughout the calls to the above
functions, struct arch_elf_state is introduced.

Finally a variant of the SET_PERSONALITY macro is introduced which
accepts a pointer to the struct arch_elf_state, allowing it to act
based upon state observed from the architecture specific program
headers.

Signed-off-by: Paul Burton 
Cc: linux-mips@linux-mips.org
Cc: Alexander Viro 
Cc: linux-fsdevel@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/7679/
Signed-off-by: Ralf Baechle

fs: make binfmt support for #! scripts modular and removable

2013-05-01T00:04:04+00:00

Add a new configuration option CONFIG_BINFMT_SCRIPT to configure support
for interpreted scripts starting with "#!"; allow compiling out that
support, or building it as a module.  Embedded systems running exclusively
compiled binaries could leave this support out, and systems that don't
need scripts before mounting the root filesystem can build this as a
module.

Signed-off-by: Josh Triplett 
Cc: Al Viro 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

coredump: make core dump functionality optional

2012-10-05T18:05:15+00:00

Adds an expert Kconfig option, CONFIG_COREDUMP, which allows disabling of
core dump.  This saves approximately 2.6k in the compiled kernel, and
complements CONFIG_ELF_CORE, which now depends on it.

CONFIG_COREDUMP also disables coredump-related sysctls, except for
suid_dumpable and related functions, which are necessary for ptrace.

[akpm@linux-foundation.org: fix binfmt_aout.c build]
Signed-off-by: Alex Kelly 
Reviewed-by: Josh Triplett 
Acked-by: Serge Hallyn 
Acked-by: Kees Cook 
Cc: Randy Dunlap 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

C6X: add support to build with BINFMT_ELF_FDPIC

2012-05-15T13:17:34+00:00

C6x userspace supports a shared library mechanism called DSBT for systems with
no MMU. DSBT is similar to FDPIC in allowing shared text segments and private
copies of data segments without an MMU. Both methods access data using a base
register and offset. With FDPIC, the caller of an external function sets up the
base register for the callee. With DSBT, the called function sets up its own
base register. Other details differ but both userspaces need the same thing
from the kernel loader: a map of where each ELF segment was loaded. The FDPIC
loader already provides this, so DSBT just uses it.

This patch enables BINFMT_ELF_FDPIC by default for C6X and provides the
necessary architecture hooks for the generic loader.

Signed-off-by: Mark Salter

fs: binfmt_elf: create Kconfig variable for PIE randomization

2012-01-11T00:30:51+00:00

Randomization of PIE load address is hard coded in binfmt_elf.c for X86
and ARM.  Create a new Kconfig variable
(CONFIG_ARCH_BINFMT_ELF_RANDOMIZE_PIE) for this and use it instead.  Thus
architecture specific policy is pushed out of the generic binfmt_elf.c and
into the architecture Kconfig files.

X86 and ARM Kconfigs are modified to select the new variable so there is
no change in behavior.  A follow on patch will select it for MIPS too.

Signed-off-by: David Daney 
Cc: Russell King 
Cc: Thomas Gleixner 
Cc: Ingo Molnar 
Cc: "H. Peter Anvin" 
Cc: Alexander Viro 
Acked-by: H. Peter Anvin 
Cc: Ralf Baechle 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

coredump: default CONFIG_CORE_DUMP_DEFAULT_ELF_HEADERS=y

2010-10-28T01:03:12+00:00

The userland ELF tools have been coping with partial-segments core files
for a few years now.  Multiple distro builds are now setting this option.
It behooves everyone who ever deals with core files to have more info
dumped in there, especially as more and more people's compilers are
producing build IDs.  Make it the default.

Anyone using older tools confused by these core files can configure this
option off, or just change /proc/PID/coredump_filter after boot.

Signed-off-by: Roland McGrath 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

CORE_DUMP_DEFAULT_ELF_HEADERS depends on ELF_CORE

2009-01-10T00:54:41+00:00

Kernels that don't support ELF coredumps at all surely can't be supporting
new partial-segment flavored ELF coredumps ...  don't make folk answer
Kconfig questions about that flavor.

Signed-off-by: David Brownell 
Acked-by: Roland McGrath 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

add CONFIG_CORE_DUMP_DEFAULT_ELF_HEADERS

2008-10-20T15:52:39+00:00

This adds a kconfig option to change the /proc/PID/coredump_filter default.
Fedora has been carrying a trivial patch to change the hard-wired value for
this default, since Fedora 8.  The default default can't change safely
because there are old GDB versions out there (all before 6.7) that are
confused by the core dump files created by the MMF_DUMP_ELF_HEADERS setting.

Signed-off-by: Roland McGrath 
Cc: Michael Kerrisk 
Cc: Oleg Nesterov 
Cc: Alan Cox 
Cc: Andi Kleen 
Cc: KOSAKI Motohiro 
Cc: Kawai Hidehiro 
Cc: Ingo Molnar 
Cc: David Jones 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds