xiaomi-sm8450/android_kernel_xiaomi_sm8450
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

arm64: Factor out PAN enabling/disabling into separate uaccess_* macros

Browse Source 
This patch moves the directly coded alternatives for turning PAN on/off
into separate uaccess_{enable,disable} macros or functions. The asm
macros take a few arguments which will be used in subsequent patches.

Note that any (unlikely) access that the compiler might generate between
uaccess_enable() and uaccess_disable(), other than those explicitly
specified by the user access code, will not be protected by PAN.

Cc: Will Deacon <will.deacon@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Kees Cook <keescook@chromium.org>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Catalin Marinas
2016-07-01 14:58:21 +01:00
parent a8ada146f5
commit bd38967d40
7 changed files with 93 additions and 58 deletions
Download Patch File Download Diff File Expand all files Collapse all files

17
arch/arm64/include/asm/futex.h
View File

@@ -21,15 +21,12 @@
#include <linux/futex.h>
#include <linux/uaccess.h>
#include <asm/alternative.h>
#include <asm/cpufeature.h>
#include <asm/errno.h>
#include <asm/sysreg.h>
#define __futex_atomic_op(insn, ret, oldval, uaddr, tmp, oparg) \
do { \
uaccess_enable(); \
asm volatile( \
ALTERNATIVE("nop", SET_PSTATE_PAN(0), ARM64_HAS_PAN, \
CONFIG_ARM64_PAN) \
" prfm pstl1strm, %2\n" \
"1: ldxr %w1, %2\n" \
insn "\n" \
@@ -44,11 +41,11 @@
" .popsection\n" \
_ASM_EXTABLE(1b, 4b) \
_ASM_EXTABLE(2b, 4b) \
ALTERNATIVE("nop", SET_PSTATE_PAN(1), ARM64_HAS_PAN, \
CONFIG_ARM64_PAN) \
: "=&r" (ret), "=&r" (oldval), "+Q" (*uaddr), "=&r" (tmp) \
: "r" (oparg), "Ir" (-EFAULT) \
: "memory")
: "memory"); \
uaccess_disable(); \
} while (0)
static inline int
futex_atomic_op_inuser (int encoded_op, u32 __user *uaddr)
@@ -118,8 +115,8 @@ futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
return -EFAULT;
uaccess_enable();
asm volatile("// futex_atomic_cmpxchg_inatomic\n"
ALTERNATIVE("nop", SET_PSTATE_PAN(0), ARM64_HAS_PAN, CONFIG_ARM64_PAN)
" prfm pstl1strm, %2\n"
"1: ldxr %w1, %2\n"
" sub %w3, %w1, %w4\n"
@@ -134,10 +131,10 @@ ALTERNATIVE("nop", SET_PSTATE_PAN(0), ARM64_HAS_PAN, CONFIG_ARM64_PAN)
" .popsection\n"
_ASM_EXTABLE(1b, 4b)
_ASM_EXTABLE(2b, 4b)
ALTERNATIVE("nop", SET_PSTATE_PAN(1), ARM64_HAS_PAN, CONFIG_ARM64_PAN)
: "+r" (ret), "=&r" (val), "+Q" (*uaddr), "=&r" (tmp)
: "r" (oldval), "r" (newval), "Ir" (-EFAULT)
: "memory");
uaccess_disable();
*uval = val;
return ret;

79
arch/arm64/include/asm/uaccess.h
View File

@@ -18,6 +18,11 @@
#ifndef __ASM_UACCESS_H
#define __ASM_UACCESS_H
#include <asm/alternative.h>
#include <asm/sysreg.h>
#ifndef __ASSEMBLY__
/*
* User space memory access functions
*/
@@ -26,10 +31,8 @@
#include <linux/string.h>
#include <linux/thread_info.h>
#include <asm/alternative.h>
#include <asm/cpufeature.h>
#include <asm/ptrace.h>
#include <asm/sysreg.h>
#include <asm/errno.h>
#include <asm/memory.h>
#include <asm/compiler.h>
@@ -119,6 +122,44 @@ static inline void set_fs(mm_segment_t fs)
" .long (" #from " - .), (" #to " - .)\n" \
" .popsection\n"
/*
* User access enabling/disabling.
*/
#define __uaccess_disable(alt) \
do { \
asm(ALTERNATIVE("nop", SET_PSTATE_PAN(1), alt, \
CONFIG_ARM64_PAN)); \
} while (0)
#define __uaccess_enable(alt) \
do { \
asm(ALTERNATIVE("nop", SET_PSTATE_PAN(0), alt, \
CONFIG_ARM64_PAN)); \
} while (0)
static inline void uaccess_disable(void)
{
__uaccess_disable(ARM64_HAS_PAN);
}
static inline void uaccess_enable(void)
{
__uaccess_enable(ARM64_HAS_PAN);
}
/*
* These functions are no-ops when UAO is present.
*/
static inline void uaccess_disable_not_uao(void)
{
__uaccess_disable(ARM64_ALT_PAN_NOT_UAO);
}
static inline void uaccess_enable_not_uao(void)
{
__uaccess_enable(ARM64_ALT_PAN_NOT_UAO);
}
/*
* The "__xxx" versions of the user access functions do not verify the address
* space - it must have been done previously with a separate "access_ok()"
@@ -146,8 +187,7 @@ static inline void set_fs(mm_segment_t fs)
do { \
unsigned long __gu_val; \
__chk_user_ptr(ptr); \
asm(ALTERNATIVE("nop", SET_PSTATE_PAN(0), ARM64_ALT_PAN_NOT_UAO,\
CONFIG_ARM64_PAN)); \
uaccess_enable_not_uao(); \
switch (sizeof(*(ptr))) { \
case 1: \
__get_user_asm("ldrb", "ldtrb", "%w", __gu_val, (ptr), \
@@ -168,9 +208,8 @@ do { \
default: \
BUILD_BUG(); \
} \
uaccess_disable_not_uao(); \
(x) = (__force __typeof__(*(ptr)))__gu_val; \
asm(ALTERNATIVE("nop", SET_PSTATE_PAN(1), ARM64_ALT_PAN_NOT_UAO,\
CONFIG_ARM64_PAN)); \
} while (0)
#define __get_user(x, ptr) \
@@ -215,8 +254,7 @@ do { \
do { \
__typeof__(*(ptr)) __pu_val = (x); \
__chk_user_ptr(ptr); \
asm(ALTERNATIVE("nop", SET_PSTATE_PAN(0), ARM64_ALT_PAN_NOT_UAO,\
CONFIG_ARM64_PAN)); \
uaccess_enable_not_uao(); \
switch (sizeof(*(ptr))) { \
case 1: \
__put_user_asm("strb", "sttrb", "%w", __pu_val, (ptr), \
@@ -237,8 +275,7 @@ do { \
default: \
BUILD_BUG(); \
} \
asm(ALTERNATIVE("nop", SET_PSTATE_PAN(1), ARM64_ALT_PAN_NOT_UAO,\
CONFIG_ARM64_PAN)); \
uaccess_disable_not_uao(); \
} while (0)
#define __put_user(x, ptr) \
@@ -331,4 +368,26 @@ extern long strncpy_from_user(char *dest, const char __user *src, long count);
extern __must_check long strlen_user(const char __user *str);
extern __must_check long strnlen_user(const char __user *str, long n);
#else /* __ASSEMBLY__ */
#include <asm/assembler.h>
/*
* User access enabling/disabling macros. These are no-ops when UAO is
* present.
*/
.macro uaccess_disable_not_uao, tmp1
alternative_if ARM64_ALT_PAN_NOT_UAO
SET_PSTATE_PAN(1)
alternative_else_nop_endif
.endm
.macro uaccess_enable_not_uao, tmp1, tmp2
alternative_if ARM64_ALT_PAN_NOT_UAO
SET_PSTATE_PAN(0)
alternative_else_nop_endif
.endm
#endif /* __ASSEMBLY__ */
#endif /* __ASM_UACCESS_H */