linux.git/fs/binfmt_elf.c, branch v4.1

fs/binfmt_elf.c:load_elf_binary(): return -EINVAL on zero-length mappings

2015-05-29T01:25:18+00:00

load_elf_binary() returns `retval', not `error'.

Fixes: a87938b2e246b81b4fb ("fs/binfmt_elf.c: fix bug in loading of PIE binaries")
Reported-by: James Hogan 
Cc: Michael Davidson 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: fold arch_randomize_brk into ARCH_HAS_ELF_RANDOMIZE

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

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: Kees Cook 
Cc: 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

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_elf.c: fix bug in loading of PIE binaries

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

With CONFIG_ARCH_BINFMT_ELF_RANDOMIZE_PIE enabled, and a normal top-down
address allocation strategy, load_elf_binary() will attempt to map a PIE
binary into an address range immediately below mm->mmap_base.

Unfortunately, load_elf_ binary() does not take account of the need to
allocate sufficient space for the entire binary which means that, while
the first PT_LOAD segment is mapped below mm->mmap_base, the subsequent
PT_LOAD segment(s) end up being mapped above mm->mmap_base into the are
that is supposed to be the "gap" between the stack and the binary.

Since the size of the "gap" on x86_64 is only guaranteed to be 128MB this
means that binaries with large data segments > 128MB can end up mapping
part of their data segment over their stack resulting in corruption of the
stack (and the data segment once the binary starts to run).

Any PIE binary with a data segment > 128MB is vulnerable to this although
address randomization means that the actual gap between the stack and the
end of the binary is normally greater than 128MB.  The larger the data
segment of the binary the higher the probability of failure.

Fix this by calculating the total size of the binary in the same way as
load_elf_interp().

Signed-off-by: Michael Davidson 
Cc: Alexander Viro 
Cc: Jiri Kosina 
Cc: Kees Cook 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

x86, mm/ASLR: Fix stack randomization on 64-bit systems

2015-02-19T11:21:36+00:00

The issue is that the stack for processes is not properly randomized on
64 bit architectures due to an integer overflow.

The affected function is randomize_stack_top() in file
"fs/binfmt_elf.c":

  static unsigned long randomize_stack_top(unsigned long stack_top)
  {
           unsigned int random_variable = 0;

           if ((current->flags & PF_RANDOMIZE) &&
                   !(current->personality & ADDR_NO_RANDOMIZE)) {
                   random_variable = get_random_int() & STACK_RND_MASK;
                   random_variable <<= PAGE_SHIFT;
           }
           return PAGE_ALIGN(stack_top) + random_variable;
           return PAGE_ALIGN(stack_top) - random_variable;
  }

Note that, it declares the "random_variable" variable as "unsigned int".
Since the result of the shifting operation between STACK_RND_MASK (which
is 0x3fffff on x86_64, 22 bits) and PAGE_SHIFT (which is 12 on x86_64):

	  random_variable <<= PAGE_SHIFT;

then the two leftmost bits are dropped when storing the result in the
"random_variable". This variable shall be at least 34 bits long to hold
the (22+12) result.

These two dropped bits have an impact on the entropy of process stack.
Concretely, the total stack entropy is reduced by four: from 2^28 to
2^30 (One fourth of expected entropy).

This patch restores back the entropy by correcting the types involved
in the operations in the functions randomize_stack_top() and
stack_maxrandom_size().

The successful fix can be tested with:

  $ for i in `seq 1 10`; do cat /proc/self/maps | grep stack; done
  7ffeda566000-7ffeda587000 rw-p 00000000 00:00 0                          [stack]
  7fff5a332000-7fff5a353000 rw-p 00000000 00:00 0                          [stack]
  7ffcdb7a1000-7ffcdb7c2000 rw-p 00000000 00:00 0                          [stack]
  7ffd5e2c4000-7ffd5e2e5000 rw-p 00000000 00:00 0                          [stack]
  ...

Once corrected, the leading bytes should be between 7ffc and 7fff,
rather than always being 7fff.

Signed-off-by: Hector Marco-Gisbert 
Signed-off-by: Ismael Ripoll 
[ Rebased, fixed 80 char bugs, cleaned up commit message, added test example and CVE ]
Signed-off-by: Kees Cook 
Cc: 
Cc: Linus Torvalds 
Cc: Andrew Morton 
Cc: Al Viro 
Fixes: CVE-2015-1593
Link: http://lkml.kernel.org/r/20150214173350.GA18393@www.outflux.net
Signed-off-by: Borislav Petkov

Merge branch 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus

2014-12-12T01:56:37+00:00

Pull MIPS updates from Ralf Baechle:
 "This is an unusually large pull request for MIPS - in parts because
  lots of patches missed the 3.18 deadline but primarily because some
  folks opened the flood gates.

   - Retire the MIPS-specific phys_t with the generic phys_addr_t.
   - Improvments for the backtrace code used by oprofile.
   - Better backtraces on SMP systems.
   - Cleanups for the Octeon platform code.
   - Cleanups and fixes for the Loongson platform code.
   - Cleanups and fixes to the firmware library.
   - Switch ATH79 platform to use the firmware library.
   - Grand overhault to the SEAD3 and Malta interrupt code.
   - Move the GIC interrupt code to drivers/irqchip
   - Lots of GIC cleanups and updates to the GIC code to use modern IRQ
     infrastructures and features of the kernel.
   - OF documentation updates for the GIC bindings
   - Move GIC clocksource driver to drivers/clocksource
   - Merge GIC clocksource driver with clockevent driver.
   - Further updates to bring the GIC clocksource driver up to date.
   - R3000 TLB code cleanups
   - Improvments to the Loongson 3 platform code.
   - Convert pr_warning to pr_warn.
   - Merge a bunch of small lantiq and ralink fixes that have been
     staged/lingering inside the openwrt tree for a while.
   - Update archhelp for IP22/IP32
   - Fix a number of issues for Loongson 1B.
   - New clocksource and clockevent driver for Loongson 1B.
   - Further work on clk handling for Loongson 1B.
   - Platform work for Broadcom BMIPS.
   - Error handling cleanups for TurboChannel.
   - Fixes and optimization to the microMIPS support.
   - Option to disable the FTLB.
   - Dump more relevant information on machine check exception
   - Change binfmt to allow arch to examine PT_*PROC headers
   - Support for new style FPU register model in O32
   - VDSO randomization.
   - BCM47xx cleanups
   - BCM47xx reimplement the way the kernel accesses NVRAM information.
   - Random cleanups
   - Add support for ATH25 platforms
   - Remove pointless locking code in some PCI platforms.
   - Some improvments to EVA support
   - Minor Alchemy cleanup"

* 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus: (185 commits)
  MIPS: Add MFHC0 and MTHC0 instructions to uasm.
  MIPS: Cosmetic cleanups of page table headers.
  MIPS: Add CP0 macros for extended EntryLo registers
  MIPS: Remove now unused definition of phys_t.
  MIPS: Replace use of phys_t with phys_addr_t.
  MIPS: Replace MIPS-specific 64BIT_PHYS_ADDR with generic PHYS_ADDR_T_64BIT
  PCMCIA: Alchemy Don't select 64BIT_PHYS_ADDR in Kconfig.
  MIPS: lib: memset: Clean up some MIPS{EL,EB} ifdefery
  MIPS: iomap: Use __mem_{read,write}{b,w,l} for MMIO
  MIPS:  fix indentation.
  MAINTAINERS: Add entry for BMIPS multiplatform kernel
  MIPS: Enable VDSO randomization
  MIPS: Remove a temporary hack for debugging cache flushes in SMTC configuration
  MIPS: Remove declaration of obsolete arch_init_clk_ops()
  MIPS: atomic.h: Reformat to fit in 79 columns
  MIPS: Apply `.insn' to fixup labels throughout
  MIPS: Fix microMIPS LL/SC immediate offsets
  MIPS: Kconfig: Only allow 32-bit microMIPS builds
  MIPS: signal.c: Fix an invalid cast in ISA mode bit handling
  MIPS: mm: Only build one microassembler that is suitable
  ...

fs/binfmt_elf.c: fix internal inconsistency relating to vma dump size

2014-12-11T01:41:12+00:00

vma_dump_size() has been used several times on actual dumper and it is
supposed to return the same value for the same vma.  But vma_dump_size()
could return different values for same vma.

The known problem case is concurrent shared memory removal.  If a vma is
used for a shared memory and that shared memory is removed between
writing program header and dumping vma memory, this will result in a
dump file which is internally consistent.

To fix the problem, we set baseline to get dump size and store the size
into vma_filesz and always use the same vma dump size which is stored in
vma_filsz.  The consistnecy with reality is not actually guranteed, but
it's tolerable since that is fully consistent with base line.

Signed-off-by: Jungseung Lee 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

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

binfmt_elf: load interpreter program headers earlier

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

Load the program headers of an ELF interpreter early enough in
load_elf_binary that they can be examined before it's too late to return
an error from an exec syscall. This patch does not perform any such
checking, it merely lays the groundwork for a further patch to do so.

No functional change is intended.

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/7675/
Signed-off-by: Ralf Baechle

binfmt_elf: Hoist ELF program header loading to a function

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

load_elf_binary & load_elf_interp both load program headers from an ELF
executable in the same way, duplicating the code. This patch introduces
a helper function (load_elf_phdrs) which performs this common task &
calls it from both load_elf_binary & load_elf_interp. In addition to
reducing code duplication, this is part of preparing to load the ELF
interpreter headers earlier such that they can be examined before it's
too late to return an error from an exec syscall.

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/7676/
Signed-off-by: Ralf Baechle