linux-stable.git/arch/mips/include/asm/elf.h, branch linux-rolling-stable

mips compat: switch to compat_binfmt_elf.c

2021-01-06T13:42:49+00:00

Like amd64, mips has two 32bit ABIs - o32 and n32.  Unlike amd64,
it does not use compat_binfmt_elf.c for either of those; each
of those ABIs has a binfmt handler of its own, both very similar
to fs/compat_binfmt_elf.c.  And the same technics as we use on
amd64 can be used to make fs/compat_binfmt_elf.c handle both.
	* merge elfo32_check_arch() with elfn32_check_arch(),
make that serve as compat_elf_check_arch().  Note that
SET_PERSONALITY2() is already the same for all ABI variants -
it looks at the elf header to choose the flags to set.
	* add asm/elfcore-compat.h, using the bigger (n32) variant
of elf32_prstatus as compat_elf_prstatus there.
	* make PRSTATUS_SIZE() and SET_PR_FPVALID() choose the
right layout, same as done for amd64.  test_thread_flag(TIF_32BIT_REGS)
is used as the predicate.

Voila - we are rid of binfmt_elf{n,o}32.c; fs/compat_binfmt_elf.c is
used, same as for all other ELF-supporting 64bit architectures that
need 32bit compat.

Signed-off-by: Al Viro

mips compat: don't bother with ELF_ET_DYN_BASE

2021-01-06T13:42:47+00:00

normal mips one is just fine - it's only used after we'd done
SET_PERSONALITY2() and by that point TASK_SIZE will yield the
right value

Signed-off-by: Al Viro

MIPS: Prevent READ_IMPLIES_EXEC propagation

2020-07-16T11:18:19+00:00

In the MIPS architecture, we should clear the security-relevant
flag READ_IMPLIES_EXEC in the function SET_PERSONALITY2() of the
file arch/mips/include/asm/elf.h.

Otherwise, with this flag set, PROT_READ implies PROT_EXEC for
mmap to make memory executable that is not safe, because this
condition allows an attacker to simply jump to and execute bytes
that are considered to be just data [1].

In mm/mmap.c:
unsigned long do_mmap(struct file *file, unsigned long addr,
			unsigned long len, unsigned long prot,
			unsigned long flags, vm_flags_t vm_flags,
			unsigned long pgoff, unsigned long *populate,
			struct list_head *uf)
{
	[...]
	if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
		if (!(file && path_noexec(&file->f_path)))
			prot |= PROT_EXEC;
	[...]
}

By the way, x86 and ARM64 have done the similar thing.

After commit 250c22777fe1 ("x86_64: move kernel"), in the file
arch/x86/kernel/process_64.c:
void set_personality_64bit(void)
{
	[...]
	current->personality &= ~READ_IMPLIES_EXEC;
}

After commit 48f99c8ec0b2 ("arm64: Preventing READ_IMPLIES_EXEC
propagation"), in the file arch/arm64/include/asm/elf.h:
#define SET_PERSONALITY(ex)						\
({									\
	clear_thread_flag(TIF_32BIT);					\
	current->personality &= ~READ_IMPLIES_EXEC;			\
})

[1] https://insights.sei.cmu.edu/cert/2014/02/feeling-insecure-blame-your-parent.html

Reported-by: Juxin Gao 
Co-developed-by: Juxin Gao 
Signed-off-by: Juxin Gao 
Signed-off-by: Tiezhu Yang 
Reviewed-by: Kees Cook 
Signed-off-by: Thomas Bogendoerfer

Use ELF_BASE_PLATFORM to pass ISA level

2020-03-19T12:09:33+00:00

Some userland application/program runtime/dynamic loaded need to
know about the current ISA level to use the best runtime.
While kernel doesn't provides this info.

ELF_PLATFORM only provides some info about the CPU, with very few info,
for example, the value is "mips" for both 24Kc and P6600.

Currently ELF_BASE_PLATFORM is not used by MIPS (only by powerpc).
So we cant set its value as:
  mips2, mips3, mips4, mips5,
  mips32, mips32r2, mips32r6
  mips64, mips64r2, mips64r6
Then in userland, we can get it by:
  getauxval(AT_BASE_PLATFORM)

The only problem is that it seems has different defination than ppc:
  on ppc, it is the mircoarchitecture
while now we use it as ISA level on MIPS.

Signed-off-by: YunQiang Su 
Reviewed-by: Jiaxun Yang 
Signed-off-by: Thomas Bogendoerfer

MIPS: Avoid FP ELF checks when CONFIG_MIPS_FP_SUPPORT=n

2018-11-09T18:23:18+00:00

When CONFIG_MIPS_FP_SUPPORT=n we don't support floating point, so we can
avoid needless checks of ELF headers specifying the FP ABI or NaN
encoding to use. Deselect CONFIG_ARCH_BINFMT_ELF_STATE in this case to
avoid the need for our arch_elf_pt_proc() & arch_check_elf() functions,
and stub out the mips_set_personality_nan() & mips_set_personality_fp()
functions such that SET_PERSONALITY() doesn't need to worry about any of
this.

Signed-off-by: Paul Burton 
Patchwork: https://patchwork.linux-mips.org/patch/21011/
Cc: linux-mips@linux-mips.org

sched/headers: Prepare to remove the dependency from

2017-03-02T07:42:37+00:00

Update code that relied on sched.h including various MM types for them.

This will allow us to remove the  include from .

Acked-by: Linus Torvalds 
Cc: Mike Galbraith 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar

MIPS: elfcore: add correct copy_regs implementations

2017-01-03T15:34:44+00:00

MIPS does not currently define ELF_CORE_COPY_REGS macros and as a result
the generic implementation is used. The generic version attempts to do
directly map (struct pt_regs) into (elf_gregset_t), which isn't correct
for MIPS platforms and also triggers a BUG() at runtime in
include/linux/elfcore.h:16 (BUG_ON(sizeof(*elfregs) != sizeof(*regs)))

[ralf@linux-mips.org: Add semicolons to the macro definitions as I do not
apply https://patchwork.linux-mips.org/patch/14588/ for now.]

Signed-off-by: Marcin Nowakowski 
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/14586/
Signed-off-by: Ralf Baechle

MIPS: Move register dump routines out of ptrace code

2017-01-03T15:34:44+00:00

Current register dump methods for MIPS are implemented inside ptrace
methods, but there will be other uses in the kernel for them, so keep
them separately in process.c and use those definitions for ptrace
instead.

Signed-off-by: Marcin Nowakowski 
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/14587/
Signed-off-by: Ralf Baechle

MIPS: non-exec stack & heap when non-exec PT_GNU_STACK is present

2016-08-02T07:29:27+00:00

The stack and heap have both been executable by default on MIPS until
now. This patch changes the default to be non-executable, but only for
ELF binaries with a non-executable PT_GNU_STACK header present. This
does apply to both the heap & the stack, despite the name PT_GNU_STACK,
and this matches the behaviour of other architectures like ARM & x86.

Current MIPS toolchains do not produce the PT_GNU_STACK header, which
means that we can rely upon this patch not changing the behaviour of
existing binaries. The new default will only take effect for newly
compiled binaries once toolchains are updated to support PT_GNU_STACK,
and since those binaries are newly compiled they can be compiled
expecting the change in default behaviour. Again this matches the way in
which the ARM & x86 architectures handled their implementations of
non-executable memory.

Signed-off-by: Paul Burton 
Cc: Leonid Yegoshin 
Cc: Maciej Rozycki 
Cc: Faraz Shahbazker 
Cc: Raghu Gandham 
Cc: Matthew Fortune 
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/13765/
Signed-off-by: Ralf Baechle

MIPS: Define AT_VECTOR_SIZE_ARCH for ARCH_DLINFO

2016-07-28T10:06:16+00:00

AT_VECTOR_SIZE_ARCH should be defined with the maximum number of
NEW_AUX_ENT entries that ARCH_DLINFO can contain, but it wasn't defined
for MIPS at all even though ARCH_DLINFO will contain one NEW_AUX_ENT for
the VDSO address.

This shouldn't be a problem as AT_VECTOR_SIZE_BASE includes space for
AT_BASE_PLATFORM which MIPS doesn't use, but lets define it now and add
the comment above ARCH_DLINFO as found in several other architectures to
remind future modifiers of ARCH_DLINFO to keep AT_VECTOR_SIZE_ARCH up to
date.

Fixes: ebb5e78cc634 ("MIPS: Initial implementation of a VDSO")
Signed-off-by: James Hogan 
Cc: linux-mips@linux-mips.org
Cc: linux-arch@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/13823/
Signed-off-by: Ralf Baechle