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BACKPORT: arm/syscalls: Optimize address limit check

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(cherry-picked from e33f8d32677fa4f4f8996ef46748f86aac81ccff)

Disable the generic address limit check in favor of an architecture
specific optimized implementation. The generic implementation using
pending work flags did not work well with ARM and alignment faults.

The address limit is checked on each syscall return path to user-mode
path as well as the irq user-mode return function. If the address limit
was changed, a function is called to report data corruption (stopping
the kernel or process based on configuration).

The address limit check has to be done before any pending work because
they can reset the address limit and the process is killed using a
SIGKILL signal. For example the lkdtm address limit check does not work
because the signal to kill the process will reset the user-mode address
limit.

Change-Id: Ic61ba05961ad1dcf10c48040427d92bd650616af
Signed-off-by: Thomas Garnier <thgarnie@google.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Tested-by: Kees Cook <keescook@chromium.org>
Tested-by: Leonard Crestez <leonard.crestez@nxp.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Pratyush Anand <panand@redhat.com>
Cc: Dave Martin <Dave.Martin@arm.com>
Cc: Will Drewry <wad@chromium.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: David Howells <dhowells@redhat.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-api@vger.kernel.org
Cc: Yonghong Song <yhs@fb.com>
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lkml.kernel.org/r/1504798247-48833-4-git-send-email-keescook@chromium.org
Signed-off-by: Satya Tangirala <satyat@google.com>
This commit is contained in:
Thomas Garnier 2017-09-07 08:30:46 -07:00 • committed by Satya Tangirala
parent 1a0df285e4
commit a8368c9815
2 changed files with 17 additions and 0 deletions
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10
arch/arm/kernel/entry-common.S
View file

@ -12,6 +12,7 @@
#include <asm/unistd.h>
#include <asm/ftrace.h>
#include <asm/unwind.h>
#include <asm/memory.h>
#ifdef CONFIG_NEED_RET_TO_USER
#include <mach/entry-macro.S>
@ -35,6 +36,9 @@ ret_fast_syscall:
UNWIND(.fnstart )
UNWIND(.cantunwind )
disable_irq_notrace @ disable interrupts
ldr r2, [tsk, #TI_ADDR_LIMIT]
cmp r2, #TASK_SIZE
blne addr_limit_check_failed
ldr r1, [tsk, #TI_FLAGS] @ re-check for syscall tracing
tst r1, #_TIF_SYSCALL_WORK | _TIF_WORK_MASK
bne fast_work_pending
@ -61,6 +65,9 @@ ret_fast_syscall:
UNWIND(.cantunwind )
str r0, [sp, #S_R0 + S_OFF]! @ save returned r0
disable_irq_notrace @ disable interrupts
ldr r2, [tsk, #TI_ADDR_LIMIT]
cmp r2, #TASK_SIZE
blne addr_limit_check_failed
ldr r1, [tsk, #TI_FLAGS] @ re-check for syscall tracing
tst r1, #_TIF_SYSCALL_WORK | _TIF_WORK_MASK
beq no_work_pending
@ -93,6 +100,9 @@ ENTRY(ret_to_user)
ret_slow_syscall:
disable_irq_notrace @ disable interrupts
ENTRY(ret_to_user_from_irq)
ldr r2, [tsk, #TI_ADDR_LIMIT]
cmp r2, #TASK_SIZE
blne addr_limit_check_failed
ldr r1, [tsk, #TI_FLAGS]
tst r1, #_TIF_WORK_MASK
bne slow_work_pending

7
arch/arm/kernel/signal.c
View file

@ -14,6 +14,7 @@
#include <linux/uaccess.h>
#include <linux/tracehook.h>
#include <linux/uprobes.h>
#include <linux/syscalls.h>
#include <asm/elf.h>
#include <asm/cacheflush.h>
@ -631,3 +632,9 @@ struct page *get_signal_page(void)
return page;
}
/* Defer to generic check */
asmlinkage void addr_limit_check_failed(void)
{
addr_limit_user_check();
}