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linux_dsm_epyc7002/arch/arm/include/asm/uaccess.h
Thomas Garnier 2404269bc4 Revert "arm/syscalls: Check address limit on user-mode return" 
This reverts commit 73ac5d6a2b.

The work pending loop can call set_fs after addr_limit_user_check
removed the _TIF_FSCHECK flag. This may happen at anytime based on how
ARM handles alignment exceptions. It leads to an infinite loop condition.

After discussion, it has been agreed that the generic approach is not
tailored to the ARM architecture and any fix might not be complete. This
patch will be replaced by an architecture specific implementation. The
work flag approach will be kept for other architectures.

Reported-by: Leonard Crestez <leonard.crestez@nxp.com>
Signed-off-by: Thomas Garnier <thgarnie@google.com>
Signed-off-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/1504798247-48833-3-git-send-email-keescook@chromium.org
2017-09-17 19:45:33 +02:00

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/*
* arch/arm/include/asm/uaccess.h
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#ifndef _ASMARM_UACCESS_H
#define _ASMARM_UACCESS_H
/*
* User space memory access functions
*/
#include <linux/string.h>
#include <asm/memory.h>
#include <asm/domain.h>
#include <asm/unified.h>
#include <asm/compiler.h>
#include <asm/extable.h>
/*
* These two functions allow hooking accesses to userspace to increase
* system integrity by ensuring that the kernel can not inadvertantly
* perform such accesses (eg, via list poison values) which could then
* be exploited for priviledge escalation.
*/
static inline unsigned int uaccess_save_and_enable(void)
{
#ifdef CONFIG_CPU_SW_DOMAIN_PAN
unsigned int old_domain = get_domain();
/* Set the current domain access to permit user accesses */
set_domain((old_domain & ~domain_mask(DOMAIN_USER)) |
domain_val(DOMAIN_USER, DOMAIN_CLIENT));
return old_domain;
#else
return 0;
#endif
}
static inline void uaccess_restore(unsigned int flags)
{
#ifdef CONFIG_CPU_SW_DOMAIN_PAN
/* Restore the user access mask */
set_domain(flags);
#endif
}
/*
* These two are intentionally not defined anywhere - if the kernel
* code generates any references to them, that's a bug.
*/
extern int __get_user_bad(void);
extern int __put_user_bad(void);
/*
* Note that this is actually 0x1,0000,0000
*/
#define KERNEL_DS 0x00000000
#define get_ds() (KERNEL_DS)
#ifdef CONFIG_MMU
#define USER_DS TASK_SIZE
#define get_fs() (current_thread_info()->addr_limit)
static inline void set_fs(mm_segment_t fs)
{
current_thread_info()->addr_limit = fs;
modify_domain(DOMAIN_KERNEL, fs ? DOMAIN_CLIENT : DOMAIN_MANAGER);
}
#define segment_eq(a, b) ((a) == (b))
/* We use 33-bit arithmetic here... */
#define __range_ok(addr, size) ({ \
unsigned long flag, roksum; \
__chk_user_ptr(addr); \
__asm__("adds %1, %2, %3; sbcccs %1, %1, %0; movcc %0, #0" \
: "=&r" (flag), "=&r" (roksum) \
: "r" (addr), "Ir" (size), "0" (current_thread_info()->addr_limit) \
: "cc"); \
flag; })
/*
* 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
* kernel data even if the calling code is buggy and fails to check
* the return value. This means zeroing out the destination variable
* or buffer on error. Normally this is done out of line by the
* fixup code, but there are a few places where it intrudes on the
* main code path. When we only write to user space, there is no
* problem.
*/
extern int __get_user_1(void *);
extern int __get_user_2(void *);
extern int __get_user_4(void *);
extern int __get_user_32t_8(void *);
extern int __get_user_8(void *);
extern int __get_user_64t_1(void *);
extern int __get_user_64t_2(void *);
extern int __get_user_64t_4(void *);
#define __GUP_CLOBBER_1 "lr", "cc"
#ifdef CONFIG_CPU_USE_DOMAINS
#define __GUP_CLOBBER_2 "ip", "lr", "cc"
#else
#define __GUP_CLOBBER_2 "lr", "cc"
#endif
#define __GUP_CLOBBER_4 "lr", "cc"
#define __GUP_CLOBBER_32t_8 "lr", "cc"
#define __GUP_CLOBBER_8 "lr", "cc"
#define __get_user_x(__r2, __p, __e, __l, __s) \
__asm__ __volatile__ ( \
__asmeq("%0", "r0") __asmeq("%1", "r2") \
__asmeq("%3", "r1") \
"bl __get_user_" #__s \
: "=&r" (__e), "=r" (__r2) \
: "0" (__p), "r" (__l) \
: __GUP_CLOBBER_##__s)
/* narrowing a double-word get into a single 32bit word register: */
#ifdef __ARMEB__
#define __get_user_x_32t(__r2, __p, __e, __l, __s) \
__get_user_x(__r2, __p, __e, __l, 32t_8)
#else
#define __get_user_x_32t __get_user_x
#endif
/*
* storing result into proper least significant word of 64bit target var,
* different only for big endian case where 64 bit __r2 lsw is r3:
*/
#ifdef __ARMEB__
#define __get_user_x_64t(__r2, __p, __e, __l, __s) \
__asm__ __volatile__ ( \
__asmeq("%0", "r0") __asmeq("%1", "r2") \
__asmeq("%3", "r1") \
"bl __get_user_64t_" #__s \
: "=&r" (__e), "=r" (__r2) \
: "0" (__p), "r" (__l) \
: __GUP_CLOBBER_##__s)
#else
#define __get_user_x_64t __get_user_x
#endif
#define __get_user_check(x, p) \
({ \
unsigned long __limit = current_thread_info()->addr_limit - 1; \
register const typeof(*(p)) __user *__p asm("r0") = (p);\
register typeof(x) __r2 asm("r2"); \
register unsigned long __l asm("r1") = __limit; \
register int __e asm("r0"); \
unsigned int __ua_flags = uaccess_save_and_enable(); \
switch (sizeof(*(__p))) { \
case 1: \
if (sizeof((x)) >= 8) \
__get_user_x_64t(__r2, __p, __e, __l, 1); \
else \
__get_user_x(__r2, __p, __e, __l, 1); \
break; \
case 2: \
if (sizeof((x)) >= 8) \
__get_user_x_64t(__r2, __p, __e, __l, 2); \
else \
__get_user_x(__r2, __p, __e, __l, 2); \
break; \
case 4: \
if (sizeof((x)) >= 8) \
__get_user_x_64t(__r2, __p, __e, __l, 4); \
else \
__get_user_x(__r2, __p, __e, __l, 4); \
break; \
case 8: \
if (sizeof((x)) < 8) \
__get_user_x_32t(__r2, __p, __e, __l, 4); \
else \
__get_user_x(__r2, __p, __e, __l, 8); \
break; \
default: __e = __get_user_bad(); break; \
} \
uaccess_restore(__ua_flags); \
x = (typeof(*(p))) __r2; \
__e; \
})
#define get_user(x, p) \
({ \
might_fault(); \
__get_user_check(x, p); \
})
extern int __put_user_1(void *, unsigned int);
extern int __put_user_2(void *, unsigned int);
extern int __put_user_4(void *, unsigned int);
extern int __put_user_8(void *, unsigned long long);
#define __put_user_check(__pu_val, __ptr, __err, __s) \
({ \
unsigned long __limit = current_thread_info()->addr_limit - 1; \
register typeof(__pu_val) __r2 asm("r2") = __pu_val; \
register const void __user *__p asm("r0") = __ptr; \
register unsigned long __l asm("r1") = __limit; \
register int __e asm("r0"); \
__asm__ __volatile__ ( \
__asmeq("%0", "r0") __asmeq("%2", "r2") \
__asmeq("%3", "r1") \
"bl __put_user_" #__s \
: "=&r" (__e) \
: "0" (__p), "r" (__r2), "r" (__l) \
: "ip", "lr", "cc"); \
__err = __e; \
})
#else /* CONFIG_MMU */
/*
* uClinux has only one addr space, so has simplified address limits.
*/
#define USER_DS KERNEL_DS
#define segment_eq(a, b) (1)
#define __addr_ok(addr) ((void)(addr), 1)
#define __range_ok(addr, size) ((void)(addr), 0)
#define get_fs() (KERNEL_DS)
static inline void set_fs(mm_segment_t fs)
{
}
#define get_user(x, p) __get_user(x, p)
#define __put_user_check __put_user_nocheck
#endif /* CONFIG_MMU */
#define access_ok(type, addr, size) (__range_ok(addr, size) == 0)
#define user_addr_max() \
(uaccess_kernel() ? ~0UL : get_fs())
/*
* 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()" call.
*
* The "xxx_error" versions set the third argument to EFAULT if an
* error occurs, and leave it unchanged on success. Note that these
* versions are void (ie, don't return a value as such).
*/
#define __get_user(x, ptr) \
({ \
long __gu_err = 0; \
__get_user_err((x), (ptr), __gu_err); \
__gu_err; \
})
#define __get_user_error(x, ptr, err) \
({ \
__get_user_err((x), (ptr), err); \
(void) 0; \
})
#define __get_user_err(x, ptr, err) \
do { \
unsigned long __gu_addr = (unsigned long)(ptr); \
unsigned long __gu_val; \
unsigned int __ua_flags; \
__chk_user_ptr(ptr); \
might_fault(); \
__ua_flags = uaccess_save_and_enable(); \
switch (sizeof(*(ptr))) { \
case 1: __get_user_asm_byte(__gu_val, __gu_addr, err); break; \
case 2: __get_user_asm_half(__gu_val, __gu_addr, err); break; \
case 4: __get_user_asm_word(__gu_val, __gu_addr, err); break; \
default: (__gu_val) = __get_user_bad(); \
} \
uaccess_restore(__ua_flags); \
(x) = (__typeof__(*(ptr)))__gu_val; \
} while (0)
#define __get_user_asm(x, addr, err, instr) \
__asm__ __volatile__( \
"1: " TUSER(instr) " %1, [%2], #0\n" \
"2:\n" \
" .pushsection .text.fixup,\"ax\"\n" \
" .align 2\n" \
"3: mov %0, %3\n" \
" mov %1, #0\n" \
" b 2b\n" \
" .popsection\n" \
" .pushsection __ex_table,\"a\"\n" \
" .align 3\n" \
" .long 1b, 3b\n" \
" .popsection" \
: "+r" (err), "=&r" (x) \
: "r" (addr), "i" (-EFAULT) \
: "cc")
#define __get_user_asm_byte(x, addr, err) \
__get_user_asm(x, addr, err, ldrb)
#ifndef __ARMEB__
#define __get_user_asm_half(x, __gu_addr, err) \
({ \
unsigned long __b1, __b2; \
__get_user_asm_byte(__b1, __gu_addr, err); \
__get_user_asm_byte(__b2, __gu_addr + 1, err); \
(x) = __b1 | (__b2 << 8); \
})
#else
#define __get_user_asm_half(x, __gu_addr, err) \
({ \
unsigned long __b1, __b2; \
__get_user_asm_byte(__b1, __gu_addr, err); \
__get_user_asm_byte(__b2, __gu_addr + 1, err); \
(x) = (__b1 << 8) | __b2; \
})
#endif
#define __get_user_asm_word(x, addr, err) \
__get_user_asm(x, addr, err, ldr)
#define __put_user_switch(x, ptr, __err, __fn) \
do { \
const __typeof__(*(ptr)) __user *__pu_ptr = (ptr); \
__typeof__(*(ptr)) __pu_val = (x); \
unsigned int __ua_flags; \
might_fault(); \
__ua_flags = uaccess_save_and_enable(); \
switch (sizeof(*(ptr))) { \
case 1: __fn(__pu_val, __pu_ptr, __err, 1); break; \
case 2: __fn(__pu_val, __pu_ptr, __err, 2); break; \
case 4: __fn(__pu_val, __pu_ptr, __err, 4); break; \
case 8: __fn(__pu_val, __pu_ptr, __err, 8); break; \
default: __err = __put_user_bad(); break; \
} \
uaccess_restore(__ua_flags); \
} while (0)
#define put_user(x, ptr) \
({ \
int __pu_err = 0; \
__put_user_switch((x), (ptr), __pu_err, __put_user_check); \
__pu_err; \
})
#define __put_user(x, ptr) \
({ \
long __pu_err = 0; \
__put_user_switch((x), (ptr), __pu_err, __put_user_nocheck); \
__pu_err; \
})
#define __put_user_error(x, ptr, err) \
({ \
__put_user_switch((x), (ptr), (err), __put_user_nocheck); \
(void) 0; \
})
#define __put_user_nocheck(x, __pu_ptr, __err, __size) \
do { \
unsigned long __pu_addr = (unsigned long)__pu_ptr; \
__put_user_nocheck_##__size(x, __pu_addr, __err); \
} while (0)
#define __put_user_nocheck_1 __put_user_asm_byte
#define __put_user_nocheck_2 __put_user_asm_half
#define __put_user_nocheck_4 __put_user_asm_word
#define __put_user_nocheck_8 __put_user_asm_dword
#define __put_user_asm(x, __pu_addr, err, instr) \
__asm__ __volatile__( \
"1: " TUSER(instr) " %1, [%2], #0\n" \
"2:\n" \
" .pushsection .text.fixup,\"ax\"\n" \
" .align 2\n" \
"3: mov %0, %3\n" \
" b 2b\n" \
" .popsection\n" \
" .pushsection __ex_table,\"a\"\n" \
" .align 3\n" \
" .long 1b, 3b\n" \
" .popsection" \
: "+r" (err) \
: "r" (x), "r" (__pu_addr), "i" (-EFAULT) \
: "cc")
#define __put_user_asm_byte(x, __pu_addr, err) \
__put_user_asm(x, __pu_addr, err, strb)
#ifndef __ARMEB__
#define __put_user_asm_half(x, __pu_addr, err) \
({ \
unsigned long __temp = (__force unsigned long)(x); \
__put_user_asm_byte(__temp, __pu_addr, err); \
__put_user_asm_byte(__temp >> 8, __pu_addr + 1, err); \
})
#else
#define __put_user_asm_half(x, __pu_addr, err) \
({ \
unsigned long __temp = (__force unsigned long)(x); \
__put_user_asm_byte(__temp >> 8, __pu_addr, err); \
__put_user_asm_byte(__temp, __pu_addr + 1, err); \
})
#endif
#define __put_user_asm_word(x, __pu_addr, err) \
__put_user_asm(x, __pu_addr, err, str)
#ifndef __ARMEB__
#define __reg_oper0 "%R2"
#define __reg_oper1 "%Q2"
#else
#define __reg_oper0 "%Q2"
#define __reg_oper1 "%R2"
#endif
#define __put_user_asm_dword(x, __pu_addr, err) \
__asm__ __volatile__( \
ARM( "1: " TUSER(str) " " __reg_oper1 ", [%1], #4\n" ) \
ARM( "2: " TUSER(str) " " __reg_oper0 ", [%1]\n" ) \
THUMB( "1: " TUSER(str) " " __reg_oper1 ", [%1]\n" ) \
THUMB( "2: " TUSER(str) " " __reg_oper0 ", [%1, #4]\n" ) \
"3:\n" \
" .pushsection .text.fixup,\"ax\"\n" \
" .align 2\n" \
"4: mov %0, %3\n" \
" b 3b\n" \
" .popsection\n" \
" .pushsection __ex_table,\"a\"\n" \
" .align 3\n" \
" .long 1b, 4b\n" \
" .long 2b, 4b\n" \
" .popsection" \
: "+r" (err), "+r" (__pu_addr) \
: "r" (x), "i" (-EFAULT) \
: "cc")
#ifdef CONFIG_MMU
extern unsigned long __must_check
arm_copy_from_user(void *to, const void __user *from, unsigned long n);
static inline unsigned long __must_check
raw_copy_from_user(void *to, const void __user *from, unsigned long n)
{
unsigned int __ua_flags;
__ua_flags = uaccess_save_and_enable();
n = arm_copy_from_user(to, from, n);
uaccess_restore(__ua_flags);
return n;
}
extern unsigned long __must_check
arm_copy_to_user(void __user *to, const void *from, unsigned long n);
extern unsigned long __must_check
__copy_to_user_std(void __user *to, const void *from, unsigned long n);
static inline unsigned long __must_check
raw_copy_to_user(void __user *to, const void *from, unsigned long n)
{
#ifndef CONFIG_UACCESS_WITH_MEMCPY
unsigned int __ua_flags;
__ua_flags = uaccess_save_and_enable();
n = arm_copy_to_user(to, from, n);
uaccess_restore(__ua_flags);
return n;
#else
return arm_copy_to_user(to, from, n);
#endif
}
extern unsigned long __must_check
arm_clear_user(void __user *addr, unsigned long n);
extern unsigned long __must_check
__clear_user_std(void __user *addr, unsigned long n);
static inline unsigned long __must_check
__clear_user(void __user *addr, unsigned long n)
{
unsigned int __ua_flags = uaccess_save_and_enable();
n = arm_clear_user(addr, n);
uaccess_restore(__ua_flags);
return n;
}
#else
static inline unsigned long
raw_copy_from_user(void *to, const void __user *from, unsigned long n)
{
memcpy(to, (const void __force *)from, n);
return 0;
}
static inline unsigned long
raw_copy_to_user(void __user *to, const void *from, unsigned long n)
{
memcpy((void __force *)to, from, n);
return 0;
}
#define __clear_user(addr, n) (memset((void __force *)addr, 0, n), 0)
#endif
#define INLINE_COPY_TO_USER
#define INLINE_COPY_FROM_USER
static inline unsigned long __must_check clear_user(void __user *to, unsigned long n)
{
if (access_ok(VERIFY_WRITE, to, n))
n = __clear_user(to, n);
return n;
}
/* These are from lib/ code, and use __get_user() and friends */
extern long strncpy_from_user(char *dest, const char __user *src, long count);
extern __must_check long strnlen_user(const char __user *str, long n);
#endif /* _ASMARM_UACCESS_H */
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