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| author | Julien Thierry <julien.thierry@arm.com> | 2019-02-14 00:32:14 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-02-20 12:25:37 +0300 |
| commit | b7a95704e9229a6f78987a0e851a6fbea407de03 (patch) | |
| tree | 3d0f88f624558dd3d6b84fb1892ce66b2ca88dc9 /arch/arm/include | |
| parent | beaf90b2d280b5bd397b8cd19b75184b1e5678f6 (diff) | |
| download | linux-b7a95704e9229a6f78987a0e851a6fbea407de03.tar.xz | |
ARM: 8796/1: spectre-v1,v1.1: provide helpers for address sanitization
Commit afaf6838f4bc896a711180b702b388b8cfa638fc upstream.
Introduce C and asm helpers to sanitize user address, taking the
address range they target into account.
Use asm helper for existing sanitization in __copy_from_user().
Signed-off-by: Julien Thierry <julien.thierry@arm.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: David A. Long <dave.long@linaro.org>
Reviewed-by: Julien Thierry <julien.thierry@arm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'arch/arm/include')
| -rw-r--r-- | arch/arm/include/asm/assembler.h | 11 | ||||
| -rw-r--r-- | arch/arm/include/asm/uaccess.h | 26 |
2 files changed, 37 insertions, 0 deletions
diff --git a/arch/arm/include/asm/assembler.h b/arch/arm/include/asm/assembler.h index b17ee03d280b..88286dd483ff 100644 --- a/arch/arm/include/asm/assembler.h +++ b/arch/arm/include/asm/assembler.h @@ -467,6 +467,17 @@ THUMB( orr \reg , \reg , #PSR_T_BIT ) #endif .endm + .macro uaccess_mask_range_ptr, addr:req, size:req, limit:req, tmp:req +#ifdef CONFIG_CPU_SPECTRE + sub \tmp, \limit, #1 + subs \tmp, \tmp, \addr @ tmp = limit - 1 - addr + addhs \tmp, \tmp, #1 @ if (tmp >= 0) { + subhss \tmp, \tmp, \size @ tmp = limit - (addr + size) } + movlo \addr, #0 @ if (tmp < 0) addr = NULL + csdb +#endif + .endm + .macro uaccess_disable, tmp, isb=1 #ifdef CONFIG_CPU_SW_DOMAIN_PAN /* diff --git a/arch/arm/include/asm/uaccess.h b/arch/arm/include/asm/uaccess.h index 1191e7da8fab..c136eef8f690 100644 --- a/arch/arm/include/asm/uaccess.h +++ b/arch/arm/include/asm/uaccess.h @@ -100,6 +100,32 @@ static inline void set_fs(mm_segment_t fs) __typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL)) /* + * Sanitise a uaccess pointer such that it becomes NULL if addr+size + * is above the current addr_limit. + */ +#define uaccess_mask_range_ptr(ptr, size) \ + ((__typeof__(ptr))__uaccess_mask_range_ptr(ptr, size)) +static inline void __user *__uaccess_mask_range_ptr(const void __user *ptr, + size_t size) +{ + void __user *safe_ptr = (void __user *)ptr; + unsigned long tmp; + + asm volatile( + " sub %1, %3, #1\n" + " subs %1, %1, %0\n" + " addhs %1, %1, #1\n" + " subhss %1, %1, %2\n" + " movlo %0, #0\n" + : "+r" (safe_ptr), "=&r" (tmp) + : "r" (size), "r" (current_thread_info()->addr_limit) + : "cc"); + + csdb(); + return safe_ptr; +} + +/* * Single-value transfer routines. They automatically use the right * size if we just have the right pointer type. Note that the functions * which read from user space (*get_*) need to take care not to leak |