The patch titled
Subject: ASLP: fix offset2lib issue for x86*, ARM*, PowerPC and MIPS
has been added to the -mm tree. Its filename is
fix-offset2lib-issue-for-x86-arm-powerpc-and-mips.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/fix-offset2lib-issue-for-x86-arm-powerpc-and-mips.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/fix-offset2lib-issue-for-x86-arm-powerpc-and-mips.patch
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*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Hector Marco Gisbert <hecmargi@xxxxxx>
Subject: ASLP: fix offset2lib issue for x86*, ARM*, PowerPC and MIPS
The issue appears on PIE linked executables when all memory areas of a
process are randomized. In this case, the attack "offset2lib"
de-randomizes all library areas on 64 bit Linux systems in less than one
second.
Further details of the PoC attack at:
http://cybersecurity.upv.es/attacks/offset2lib/offset2lib.html
This patch loads the PIE linked executable in a different area than the
libraries. The successful fix can be tested with a simple pie compiled
application:
$ ./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]
Once corrected, the PIE linked application is loaded in a different area.
We updated the "Fixing Offset2lib weakness" page:
http://cybersecurity.upv.es/solutions/aslrv2/aslrv2.html
Signed-off-by: Hector Marco-Gisbert <hecmargi@xxxxxx>
Signed-off-by: Ismael Ripoll <iripoll@xxxxxx>
Acked-by: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Russell King <rmk@xxxxxxxxxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Will Deacon <will.deacon@xxxxxxx>
Cc: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/arm/Kconfig | 1 -
arch/arm/include/asm/elf.h | 3 ++-
arch/arm/mm/mmap.c | 21 +++++++++++++++++++++
arch/arm64/Kconfig | 1 -
arch/arm64/include/asm/elf.h | 4 ++--
arch/arm64/mm/mmap.c | 10 ++++++++++
arch/mips/Kconfig | 1 -
arch/mips/include/asm/elf.h | 3 ++-
arch/mips/mm/mmap.c | 10 ++++++++++
arch/powerpc/Kconfig | 1 -
arch/powerpc/include/asm/elf.h | 3 ++-
arch/powerpc/mm/mmap.c | 10 ++++++++++
arch/x86/Kconfig | 1 -
arch/x86/include/asm/elf.h | 3 ++-
arch/x86/mm/mmap.c | 9 +++++++++
fs/Kconfig.binfmt | 2 --
fs/binfmt_elf.c | 14 --------------
17 files changed, 70 insertions(+), 27 deletions(-)
diff -puN arch/arm/Kconfig~fix-offset2lib-issue-for-x86-arm-powerpc-and-mips arch/arm/Kconfig
--- a/arch/arm/Kconfig~fix-offset2lib-issue-for-x86-arm-powerpc-and-mips
+++ a/arch/arm/Kconfig
@@ -1,7 +1,6 @@
config ARM
bool
default y
- select ARCH_BINFMT_ELF_RANDOMIZE_PIE
select ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE
select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
select ARCH_HAVE_CUSTOM_GPIO_H
diff -puN arch/arm/include/asm/elf.h~fix-offset2lib-issue-for-x86-arm-powerpc-and-mips arch/arm/include/asm/elf.h
--- a/arch/arm/include/asm/elf.h~fix-offset2lib-issue-for-x86-arm-powerpc-and-mips
+++ a/arch/arm/include/asm/elf.h
@@ -115,7 +115,8 @@ int dump_task_regs(struct task_struct *t
the loader. We need to make sure that it is out of the way of the program
that it will "exec", and that there is sufficient room for the brk. */
-#define ELF_ET_DYN_BASE (2 * TASK_SIZE / 3)
+extern unsigned long randomize_et_dyn(unsigned long base);
+#define ELF_ET_DYN_BASE (randomize_et_dyn(2 * TASK_SIZE / 3))
/* When the program starts, a1 contains a pointer to a function to be
registered with atexit, as per the SVR4 ABI. A value of 0 means we
diff -puN arch/arm/mm/mmap.c~fix-offset2lib-issue-for-x86-arm-powerpc-and-mips arch/arm/mm/mmap.c
--- a/arch/arm/mm/mmap.c~fix-offset2lib-issue-for-x86-arm-powerpc-and-mips
+++ a/arch/arm/mm/mmap.c
@@ -30,6 +30,17 @@ static int mmap_is_legacy(void)
return sysctl_legacy_va_layout;
}
+static unsigned long mmap_rnd(void)
+{
+ unsigned long rnd = 0;
+
+ /* 8 bits of randomness in 20 address space bits */
+ if (current->flags & PF_RANDOMIZE)
+ rnd = (long)get_random_int() % (1 << 8);
+
+ return rnd << PAGE_SHIFT;
+}
+
static unsigned long mmap_base(unsigned long rnd)
{
unsigned long gap = rlimit(RLIMIT_STACK);
@@ -230,3 +241,13 @@ int devmem_is_allowed(unsigned long pfn)
}
#endif
+
+unsigned long randomize_et_dyn(unsigned long base)
+{
+ unsigned long ret;
+ if ((current->personality & ADDR_NO_RANDOMIZE) ||
+ !(current->flags & PF_RANDOMIZE))
+ return base;
+ ret = base + mmap_rnd();
+ return (ret > base) ? ret : base;
+}
diff -puN arch/arm64/Kconfig~fix-offset2lib-issue-for-x86-arm-powerpc-and-mips arch/arm64/Kconfig
--- a/arch/arm64/Kconfig~fix-offset2lib-issue-for-x86-arm-powerpc-and-mips
+++ a/arch/arm64/Kconfig
@@ -1,6 +1,5 @@
config ARM64
def_bool y
- select ARCH_BINFMT_ELF_RANDOMIZE_PIE
select ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE
select ARCH_HAS_GCOV_PROFILE_ALL
select ARCH_HAS_SG_CHAIN
diff -puN arch/arm64/include/asm/elf.h~fix-offset2lib-issue-for-x86-arm-powerpc-and-mips arch/arm64/include/asm/elf.h
--- a/arch/arm64/include/asm/elf.h~fix-offset2lib-issue-for-x86-arm-powerpc-and-mips
+++ a/arch/arm64/include/asm/elf.h
@@ -126,7 +126,7 @@ typedef struct user_fpsimd_state elf_fpr
* that it will "exec", and that there is sufficient room for the brk.
*/
extern unsigned long randomize_et_dyn(unsigned long base);
-#define ELF_ET_DYN_BASE (2 * TASK_SIZE_64 / 3)
+#define ELF_ET_DYN_BASE (randomize_et_dyn(2 * TASK_SIZE_64 / 3))
/*
* When the program starts, a1 contains a pointer to a function to be
@@ -169,7 +169,7 @@ extern unsigned long arch_randomize_brk(
#define COMPAT_ELF_PLATFORM ("v8l")
#endif
-#define COMPAT_ELF_ET_DYN_BASE (2 * TASK_SIZE_32 / 3)
+#define COMPAT_ELF_ET_DYN_BASE (randomize_et_dyn(2 * TASK_SIZE_32 / 3))
/* AArch32 registers. */
#define COMPAT_ELF_NGREG 18
diff -puN arch/arm64/mm/mmap.c~fix-offset2lib-issue-for-x86-arm-powerpc-and-mips arch/arm64/mm/mmap.c
--- a/arch/arm64/mm/mmap.c~fix-offset2lib-issue-for-x86-arm-powerpc-and-mips
+++ a/arch/arm64/mm/mmap.c
@@ -89,6 +89,16 @@ void arch_pick_mmap_layout(struct mm_str
}
EXPORT_SYMBOL_GPL(arch_pick_mmap_layout);
+unsigned long randomize_et_dyn(unsigned long base)
+{
+ unsigned long ret;
+ if ((current->personality & ADDR_NO_RANDOMIZE) ||
+ !(current->flags & PF_RANDOMIZE))
+ return base;
+ ret = base + mmap_rnd();
+ return (ret > base) ? ret : base;
+}
+
/*
* You really shouldn't be using read() or write() on /dev/mem. This might go
diff -puN arch/mips/Kconfig~fix-offset2lib-issue-for-x86-arm-powerpc-and-mips arch/mips/Kconfig
--- a/arch/mips/Kconfig~fix-offset2lib-issue-for-x86-arm-powerpc-and-mips
+++ a/arch/mips/Kconfig
@@ -23,7 +23,6 @@ config MIPS
select HAVE_KRETPROBES
select HAVE_DEBUG_KMEMLEAK
select HAVE_SYSCALL_TRACEPOINTS
- select ARCH_BINFMT_ELF_RANDOMIZE_PIE
select HAVE_ARCH_TRANSPARENT_HUGEPAGE if CPU_SUPPORTS_HUGEPAGES && 64BIT
select RTC_LIB if !MACH_LOONGSON
select GENERIC_ATOMIC64 if !64BIT
diff -puN arch/mips/include/asm/elf.h~fix-offset2lib-issue-for-x86-arm-powerpc-and-mips arch/mips/include/asm/elf.h
--- a/arch/mips/include/asm/elf.h~fix-offset2lib-issue-for-x86-arm-powerpc-and-mips
+++ a/arch/mips/include/asm/elf.h
@@ -402,7 +402,8 @@ extern const char *__elf_platform;
that it will "exec", and that there is sufficient room for the brk. */
#ifndef ELF_ET_DYN_BASE
-#define ELF_ET_DYN_BASE (TASK_SIZE / 3 * 2)
+extern unsigned long randomize_et_dyn(unsigned long base);
+#define ELF_ET_DYN_BASE (randomize_et_dyn(TASK_SIZE / 3 * 2))
#endif
#define ARCH_HAS_SETUP_ADDITIONAL_PAGES 1
diff -puN arch/mips/mm/mmap.c~fix-offset2lib-issue-for-x86-arm-powerpc-and-mips arch/mips/mm/mmap.c
--- a/arch/mips/mm/mmap.c~fix-offset2lib-issue-for-x86-arm-powerpc-and-mips
+++ a/arch/mips/mm/mmap.c
@@ -196,3 +196,13 @@ int __virt_addr_valid(const volatile voi
return pfn_valid(PFN_DOWN(virt_to_phys(kaddr)));
}
EXPORT_SYMBOL_GPL(__virt_addr_valid);
+
+unsigned long randomize_et_dyn(unsigned long base)
+{
+ unsigned long ret;
+ if ((current->personality & ADDR_NO_RANDOMIZE) ||
+ !(current->flags & PF_RANDOMIZE))
+ return base;
+ ret = base + brk_rnd();
+ return (ret > base) ? ret : base;
+}
diff -puN arch/powerpc/Kconfig~fix-offset2lib-issue-for-x86-arm-powerpc-and-mips arch/powerpc/Kconfig
--- a/arch/powerpc/Kconfig~fix-offset2lib-issue-for-x86-arm-powerpc-and-mips
+++ a/arch/powerpc/Kconfig
@@ -88,7 +88,6 @@ config PPC
select ARCH_MIGHT_HAVE_PC_PARPORT
select ARCH_MIGHT_HAVE_PC_SERIO
select BINFMT_ELF
- select ARCH_BINFMT_ELF_RANDOMIZE_PIE
select OF
select OF_EARLY_FLATTREE
select OF_RESERVED_MEM
diff -puN arch/powerpc/include/asm/elf.h~fix-offset2lib-issue-for-x86-arm-powerpc-and-mips arch/powerpc/include/asm/elf.h
--- a/arch/powerpc/include/asm/elf.h~fix-offset2lib-issue-for-x86-arm-powerpc-and-mips
+++ a/arch/powerpc/include/asm/elf.h
@@ -28,7 +28,8 @@
the loader. We need to make sure that it is out of the way of the program
that it will "exec", and that there is sufficient room for the brk. */
-#define ELF_ET_DYN_BASE 0x20000000
+extern unsigned long randomize_et_dyn(unsigned long base);
+#define ELF_ET_DYN_BASE (randomize_et_dyn(0x20000000))
#define ELF_CORE_EFLAGS (is_elf2_task() ? 2 : 0)
diff -puN arch/powerpc/mm/mmap.c~fix-offset2lib-issue-for-x86-arm-powerpc-and-mips arch/powerpc/mm/mmap.c
--- a/arch/powerpc/mm/mmap.c~fix-offset2lib-issue-for-x86-arm-powerpc-and-mips
+++ a/arch/powerpc/mm/mmap.c
@@ -97,3 +97,13 @@ void arch_pick_mmap_layout(struct mm_str
mm->get_unmapped_area = arch_get_unmapped_area_topdown;
}
}
+
+unsigned long randomize_et_dyn(unsigned long base)
+{
+ unsigned long ret;
+ if ((current->personality & ADDR_NO_RANDOMIZE) ||
+ !(current->flags & PF_RANDOMIZE))
+ return base;
+ ret = base + mmap_rnd();
+ return (ret > base) ? ret : base;
+}
diff -puN arch/x86/Kconfig~fix-offset2lib-issue-for-x86-arm-powerpc-and-mips arch/x86/Kconfig
--- a/arch/x86/Kconfig~fix-offset2lib-issue-for-x86-arm-powerpc-and-mips
+++ a/arch/x86/Kconfig
@@ -87,7 +87,6 @@ config X86
select HAVE_ARCH_KMEMCHECK
select HAVE_ARCH_KASAN if X86_64 && SPARSEMEM_VMEMMAP
select HAVE_USER_RETURN_NOTIFIER
- select ARCH_BINFMT_ELF_RANDOMIZE_PIE
select HAVE_ARCH_JUMP_LABEL
select ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE
select SPARSE_IRQ
diff -puN arch/x86/include/asm/elf.h~fix-offset2lib-issue-for-x86-arm-powerpc-and-mips arch/x86/include/asm/elf.h
--- a/arch/x86/include/asm/elf.h~fix-offset2lib-issue-for-x86-arm-powerpc-and-mips
+++ a/arch/x86/include/asm/elf.h
@@ -249,7 +249,8 @@ extern int force_personality32;
the loader. We need to make sure that it is out of the way of the program
that it will "exec", and that there is sufficient room for the brk. */
-#define ELF_ET_DYN_BASE (TASK_SIZE / 3 * 2)
+extern unsigned long randomize_et_dyn(unsigned long base);
+#define ELF_ET_DYN_BASE (randomize_et_dyn(TASK_SIZE / 3 * 2))
/* This yields a mask that user programs can use to figure out what
instruction set this CPU supports. This could be done in user space,
diff -puN arch/x86/mm/mmap.c~fix-offset2lib-issue-for-x86-arm-powerpc-and-mips arch/x86/mm/mmap.c
--- a/arch/x86/mm/mmap.c~fix-offset2lib-issue-for-x86-arm-powerpc-and-mips
+++ a/arch/x86/mm/mmap.c
@@ -122,3 +122,12 @@ void arch_pick_mmap_layout(struct mm_str
mm->get_unmapped_area = arch_get_unmapped_area_topdown;
}
}
+unsigned long randomize_et_dyn(unsigned long base)
+{
+ unsigned long ret;
+ if ((current->personality & ADDR_NO_RANDOMIZE) ||
+ !(current->flags & PF_RANDOMIZE))
+ return base;
+ ret = base + mmap_rnd();
+ return (ret > base) ? ret : base;
+}
diff -puN fs/Kconfig.binfmt~fix-offset2lib-issue-for-x86-arm-powerpc-and-mips fs/Kconfig.binfmt
--- a/fs/Kconfig.binfmt~fix-offset2lib-issue-for-x86-arm-powerpc-and-mips
+++ a/fs/Kconfig.binfmt
@@ -27,8 +27,6 @@ config COMPAT_BINFMT_ELF
bool
depends on COMPAT && BINFMT_ELF
-config ARCH_BINFMT_ELF_RANDOMIZE_PIE
- bool
config ARCH_BINFMT_ELF_STATE
bool
diff -puN fs/binfmt_elf.c~fix-offset2lib-issue-for-x86-arm-powerpc-and-mips fs/binfmt_elf.c
--- a/fs/binfmt_elf.c~fix-offset2lib-issue-for-x86-arm-powerpc-and-mips
+++ a/fs/binfmt_elf.c
@@ -909,21 +909,7 @@ static int load_elf_binary(struct linux_
* default mmap base, as well as whatever program they
* might try to exec. This is because the brk will
* follow the loader, and is not movable. */
-#ifdef CONFIG_ARCH_BINFMT_ELF_RANDOMIZE_PIE
- /* Memory randomization might have been switched off
- * in runtime via sysctl or explicit setting of
- * personality flags.
- * If that is the case, retain the original non-zero
- * load_bias value in order to establish proper
- * non-randomized mappings.
- */
- if (current->flags & PF_RANDOMIZE)
- load_bias = 0;
- else
- load_bias = ELF_PAGESTART(ELF_ET_DYN_BASE - vaddr);
-#else
load_bias = ELF_PAGESTART(ELF_ET_DYN_BASE - vaddr);
-#endif
}
error = elf_map(bprm->file, load_bias + vaddr, elf_ppnt,
_
Patches currently in -mm which might be from hecmargi@xxxxxx are
mips-rename-brk_rnd-to-mmap_rnd.patch
fix-offset2lib-issue-for-x86-arm-powerpc-and-mips.patch
fix-offset2lib-issue-for-x86-arm-powerpc-and-mips-fix.patch
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