diff options
| author | David Brown <david.brown@linaro.org> | 2016-02-17 14:41:18 -0800 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2016-02-22 08:51:39 +0100 |
| commit | 11bf9b865898961cee60a41c483c9f27ec76e12e (patch) | |
| tree | b1bf9ec472b77256c749da4a24e3fd689f7c87db | |
| parent | 018ef8dcf3de5f62e2cc1a9273cc27e1c6ba8de5 (diff) | |
ARM/vdso: Mark the vDSO code read-only after init
Although the ARM vDSO is cleanly separated by code/data with the code
being read-only in userspace mappings, the code page is still writable
from the kernel.
There have been exploits (such as http://itszn.com/blog/?p=21) that
take advantage of this on x86 to go from a bad kernel write to full
root.
Prevent this specific exploit class on ARM as well by putting the vDSO
code page in post-init read-only memory as well.
Before:
vdso: 1 text pages at base 80927000
root@Vexpress:/ cat /sys/kernel/debug/kernel_page_tables
---[ Modules ]---
---[ Kernel Mapping ]---
0x80000000-0x80100000 1M RW NX SHD
0x80100000-0x80600000 5M ro x SHD
0x80600000-0x80800000 2M ro NX SHD
0x80800000-0xbe000000 984M RW NX SHD
After:
vdso: 1 text pages at base 8072b000
root@Vexpress:/ cat /sys/kernel/debug/kernel_page_tables
---[ Modules ]---
---[ Kernel Mapping ]---
0x80000000-0x80100000 1M RW NX SHD
0x80100000-0x80600000 5M ro x SHD
0x80600000-0x80800000 2M ro NX SHD
0x80800000-0xbe000000 984M RW NX SHD
Inspired by https://lkml.org/lkml/2016/1/19/494 based on work by the
PaX Team, Brad Spengler, and Kees Cook.
Signed-off-by: David Brown <david.brown@linaro.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brad Spengler <spender@grsecurity.net>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Emese Revfy <re.emese@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mathias Krause <minipli@googlemail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nathan Lynch <nathan_lynch@mentor.com>
Cc: PaX Team <pageexec@freemail.hu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: kernel-hardening@lists.openwall.com
Cc: linux-arch <linux-arch@vger.kernel.org>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/1455748879-21872-8-git-send-email-keescook@chromium.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
| -rw-r--r-- | arch/arm/vdso/vdso.S | 3 |
1 files changed, 1 insertions, 2 deletions
diff --git a/arch/arm/vdso/vdso.S b/arch/arm/vdso/vdso.S index b2b97e3e7bab..a62a7b64f49c 100644 --- a/arch/arm/vdso/vdso.S +++ b/arch/arm/vdso/vdso.S @@ -23,9 +23,8 @@ #include <linux/const.h> #include <asm/page.h> - __PAGE_ALIGNED_DATA - .globl vdso_start, vdso_end + .section .data..ro_after_init .balign PAGE_SIZE vdso_start: .incbin "arch/arm/vdso/vdso.so" |