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    Subject[PATCH 3.19.y-ckt 12/54] mm: expose arch_mmap_rnd when available
    Date
    3.19.8-ckt21 -stable review patch.  If anyone has any objections, please let me know.

    ---8<------------------------------------------------------------

    From: Kees Cook <keescook@chromium.org>

    commit 2b68f6caeac271620cd2f9362aeaed360e317df0 upstream.

    When an architecture fully supports randomizing the ELF load location,
    a per-arch mmap_rnd() function is used to find a randomized mmap base.
    In preparation for randomizing the location of ET_DYN binaries
    separately from mmap, this renames and exports these functions as
    arch_mmap_rnd(). Additionally introduces CONFIG_ARCH_HAS_ELF_RANDOMIZE
    for describing this feature on architectures that support it
    (which is a superset of ARCH_BINFMT_ELF_RANDOMIZE_PIE, since s390
    already supports a separated ET_DYN ASLR from mmap ASLR without the
    ARCH_BINFMT_ELF_RANDOMIZE_PIE logic).

    Signed-off-by: Kees Cook <keescook@chromium.org>
    Cc: Hector Marco-Gisbert <hecmargi@upv.es>
    Cc: Russell King <linux@arm.linux.org.uk>
    Reviewed-by: Ingo 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: Andrew Morton <akpm@linux-foundation.org>
    Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
    Signed-off-by: Kamal Mostafa <kamal@canonical.com>
    ---
    arch/Kconfig | 7 +++++++
    arch/arm/Kconfig | 1 +
    arch/arm/mm/mmap.c | 4 ++--
    arch/arm64/Kconfig | 1 +
    arch/arm64/mm/mmap.c | 4 ++--
    arch/mips/Kconfig | 1 +
    arch/mips/mm/mmap.c | 4 ++--
    arch/powerpc/Kconfig | 1 +
    arch/powerpc/mm/mmap.c | 4 ++--
    arch/s390/Kconfig | 1 +
    arch/s390/mm/mmap.c | 8 ++++----
    arch/x86/Kconfig | 1 +
    arch/x86/mm/mmap.c | 4 ++--
    include/linux/elf-randomize.h | 10 ++++++++++
    14 files changed, 37 insertions(+), 14 deletions(-)
    create mode 100644 include/linux/elf-randomize.h

    diff --git a/arch/Kconfig b/arch/Kconfig
    index 05d7a8a..9ff5aa8 100644
    --- a/arch/Kconfig
    +++ b/arch/Kconfig
    @@ -484,6 +484,13 @@ config HAVE_IRQ_EXIT_ON_IRQ_STACK
    This spares a stack switch and improves cache usage on softirq
    processing.

    +config ARCH_HAS_ELF_RANDOMIZE
    + bool
    + help
    + An architecture supports choosing randomized locations for
    + stack, mmap, brk, and ET_DYN. Defined functions:
    + - arch_mmap_rnd()
    +
    #
    # ABI hall of shame
    #
    diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
    index 3e0ad6c..8239faa 100644
    --- a/arch/arm/Kconfig
    +++ b/arch/arm/Kconfig
    @@ -3,6 +3,7 @@ config ARM
    default y
    select ARCH_BINFMT_ELF_RANDOMIZE_PIE
    select ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE
    + select ARCH_HAS_ELF_RANDOMIZE
    select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
    select ARCH_HAVE_CUSTOM_GPIO_H
    select ARCH_HAS_GCOV_PROFILE_ALL
    diff --git a/arch/arm/mm/mmap.c b/arch/arm/mm/mmap.c
    index 15a8160..407dc78 100644
    --- a/arch/arm/mm/mmap.c
    +++ b/arch/arm/mm/mmap.c
    @@ -169,7 +169,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
    return addr;
    }

    -static unsigned long mmap_rnd(void)
    +unsigned long arch_mmap_rnd(void)
    {
    unsigned long rnd;

    @@ -184,7 +184,7 @@ void arch_pick_mmap_layout(struct mm_struct *mm)
    unsigned long random_factor = 0UL;

    if (current->flags & PF_RANDOMIZE)
    - random_factor = mmap_rnd();
    + random_factor = arch_mmap_rnd();

    if (mmap_is_legacy()) {
    mm->mmap_base = TASK_UNMAPPED_BASE + random_factor;
    diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
    index 67f5ba5..15de145 100644
    --- a/arch/arm64/Kconfig
    +++ b/arch/arm64/Kconfig
    @@ -2,6 +2,7 @@ config ARM64
    def_bool y
    select ARCH_BINFMT_ELF_RANDOMIZE_PIE
    select ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE
    + select ARCH_HAS_ELF_RANDOMIZE
    select ARCH_HAS_GCOV_PROFILE_ALL
    select ARCH_HAS_SG_CHAIN
    select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
    diff --git a/arch/arm64/mm/mmap.c b/arch/arm64/mm/mmap.c
    index ba776c0..ed17747 100644
    --- a/arch/arm64/mm/mmap.c
    +++ b/arch/arm64/mm/mmap.c
    @@ -47,7 +47,7 @@ static int mmap_is_legacy(void)
    return sysctl_legacy_va_layout;
    }

    -static unsigned long mmap_rnd(void)
    +unsigned long arch_mmap_rnd(void)
    {
    unsigned long rnd;

    @@ -77,7 +77,7 @@ void arch_pick_mmap_layout(struct mm_struct *mm)
    unsigned long random_factor = 0UL;

    if (current->flags & PF_RANDOMIZE)
    - random_factor = mmap_rnd();
    + random_factor = arch_mmap_rnd();

    /*
    * Fall back to the standard layout if the personality bit is set, or
    diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
    index 023b29b..f50c77f 100644
    --- a/arch/mips/Kconfig
    +++ b/arch/mips/Kconfig
    @@ -24,6 +24,7 @@ config MIPS
    select HAVE_DEBUG_KMEMLEAK
    select HAVE_SYSCALL_TRACEPOINTS
    select ARCH_BINFMT_ELF_RANDOMIZE_PIE
    + select ARCH_HAS_ELF_RANDOMIZE
    select HAVE_ARCH_TRANSPARENT_HUGEPAGE if CPU_SUPPORTS_HUGEPAGES && 64BIT
    select RTC_LIB if !MACH_LOONGSON
    select GENERIC_ATOMIC64 if !64BIT
    diff --git a/arch/mips/mm/mmap.c b/arch/mips/mm/mmap.c
    index 9a4f1f5..5c81fdd 100644
    --- a/arch/mips/mm/mmap.c
    +++ b/arch/mips/mm/mmap.c
    @@ -142,7 +142,7 @@ unsigned long arch_get_unmapped_area_topdown(struct file *filp,
    addr0, len, pgoff, flags, DOWN);
    }

    -static unsigned long mmap_rnd(void)
    +unsigned long arch_mmap_rnd(void)
    {
    unsigned long rnd;

    @@ -161,7 +161,7 @@ void arch_pick_mmap_layout(struct mm_struct *mm)
    unsigned long random_factor = 0UL;

    if (current->flags & PF_RANDOMIZE)
    - random_factor = mmap_rnd();
    + random_factor = arch_mmap_rnd();

    if (mmap_is_legacy()) {
    mm->mmap_base = TASK_UNMAPPED_BASE + random_factor;
    diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
    index a2a168e..e3cd949 100644
    --- a/arch/powerpc/Kconfig
    +++ b/arch/powerpc/Kconfig
    @@ -89,6 +89,7 @@ config PPC
    select ARCH_MIGHT_HAVE_PC_SERIO
    select BINFMT_ELF
    select ARCH_BINFMT_ELF_RANDOMIZE_PIE
    + select ARCH_HAS_ELF_RANDOMIZE
    select OF
    select OF_EARLY_FLATTREE
    select OF_RESERVED_MEM
    diff --git a/arch/powerpc/mm/mmap.c b/arch/powerpc/mm/mmap.c
    index 1ad2299..0f0502e 100644
    --- a/arch/powerpc/mm/mmap.c
    +++ b/arch/powerpc/mm/mmap.c
    @@ -53,7 +53,7 @@ static inline int mmap_is_legacy(void)
    return sysctl_legacy_va_layout;
    }

    -static unsigned long mmap_rnd(void)
    +unsigned long arch_mmap_rnd(void)
    {
    unsigned long rnd;

    @@ -87,7 +87,7 @@ void arch_pick_mmap_layout(struct mm_struct *mm)
    unsigned long random_factor = 0UL;

    if (current->flags & PF_RANDOMIZE)
    - random_factor = mmap_rnd();
    + random_factor = arch_mmap_rnd();

    /*
    * Fall back to the standard layout if the personality
    diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
    index 68b68d7..d64fca0 100644
    --- a/arch/s390/Kconfig
    +++ b/arch/s390/Kconfig
    @@ -65,6 +65,7 @@ config S390
    def_bool y
    select ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE
    select ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
    + select ARCH_HAS_ELF_RANDOMIZE
    select ARCH_HAS_GCOV_PROFILE_ALL
    select ARCH_HAVE_NMI_SAFE_CMPXCHG
    select ARCH_INLINE_READ_LOCK
    diff --git a/arch/s390/mm/mmap.c b/arch/s390/mm/mmap.c
    index db57078..a94504d 100644
    --- a/arch/s390/mm/mmap.c
    +++ b/arch/s390/mm/mmap.c
    @@ -60,7 +60,7 @@ static inline int mmap_is_legacy(void)
    return sysctl_legacy_va_layout;
    }

    -static unsigned long mmap_rnd(void)
    +unsigned long arch_mmap_rnd(void)
    {
    if (is_32bit_task())
    return (get_random_int() & 0x7ff) << PAGE_SHIFT;
    @@ -187,7 +187,7 @@ unsigned long randomize_et_dyn(void)
    base &= ~((1UL << 32) - 1);

    if (current->flags & PF_RANDOMIZE)
    - base += mmap_rnd();
    + base += arch_mmap_rnd();

    return base;
    }
    @@ -203,7 +203,7 @@ void arch_pick_mmap_layout(struct mm_struct *mm)
    unsigned long random_factor = 0UL;

    if (current->flags & PF_RANDOMIZE)
    - random_factor = mmap_rnd();
    + random_factor = arch_mmap_rnd();

    /*
    * Fall back to the standard layout if the personality
    @@ -283,7 +283,7 @@ void arch_pick_mmap_layout(struct mm_struct *mm)
    unsigned long random_factor = 0UL;

    if (current->flags & PF_RANDOMIZE)
    - random_factor = mmap_rnd();
    + random_factor = arch_mmap_rnd();

    /*
    * Fall back to the standard layout if the personality
    diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
    index 0dc9d01..ea88e5d 100644
    --- a/arch/x86/Kconfig
    +++ b/arch/x86/Kconfig
    @@ -86,6 +86,7 @@ config X86
    select HAVE_ARCH_KMEMCHECK
    select HAVE_USER_RETURN_NOTIFIER
    select ARCH_BINFMT_ELF_RANDOMIZE_PIE
    + select ARCH_HAS_ELF_RANDOMIZE
    select HAVE_ARCH_JUMP_LABEL
    select ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE
    select SPARSE_IRQ
    diff --git a/arch/x86/mm/mmap.c b/arch/x86/mm/mmap.c
    index 0d9f14a..844b06d 100644
    --- a/arch/x86/mm/mmap.c
    +++ b/arch/x86/mm/mmap.c
    @@ -65,7 +65,7 @@ static int mmap_is_legacy(void)
    return sysctl_legacy_va_layout;
    }

    -static unsigned long mmap_rnd(void)
    +unsigned long arch_mmap_rnd(void)
    {
    unsigned long rnd;

    @@ -114,7 +114,7 @@ void arch_pick_mmap_layout(struct mm_struct *mm)
    unsigned long random_factor = 0UL;

    if (current->flags & PF_RANDOMIZE)
    - random_factor = mmap_rnd();
    + random_factor = arch_mmap_rnd();

    mm->mmap_legacy_base = mmap_legacy_base(random_factor);

    diff --git a/include/linux/elf-randomize.h b/include/linux/elf-randomize.h
    new file mode 100644
    index 0000000..7a4eda0
    --- /dev/null
    +++ b/include/linux/elf-randomize.h
    @@ -0,0 +1,10 @@
    +#ifndef _ELF_RANDOMIZE_H
    +#define _ELF_RANDOMIZE_H
    +
    +#ifndef CONFIG_ARCH_HAS_ELF_RANDOMIZE
    +static inline unsigned long arch_mmap_rnd(void) { return 0; }
    +#else
    +extern unsigned long arch_mmap_rnd(void);
    +#endif
    +
    +#endif
    --
    2.7.4
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