/* SPDX-License-Identifier: GPL-2.0 */ #ifndef _ASM_X86_UACCESS_H #define _ASM_X86_UACCESS_H /* * User space memory access functions */ #include #include #include #include #include #include #include /* * The fs value determines whether argument validity checking should be * performed or not. If get_fs() == USER_DS, checking is performed, with * get_fs() == KERNEL_DS, checking is bypassed. * * For historical reasons, these macros are grossly misnamed. */ #define MAKE_MM_SEG(s) ((mm_segment_t) { (s) }) #define KERNEL_DS MAKE_MM_SEG(-1UL) #define USER_DS MAKE_MM_SEG(TASK_SIZE_MAX) #define get_fs() (current->thread.addr_limit) static inline void set_fs(mm_segment_t fs) { current->thread.addr_limit = fs; /* On user-mode return, check fs is correct */ set_thread_flag(TIF_FSCHECK); } #define segment_eq(a, b) ((a).seg == (b).seg) #define user_addr_max() (current->thread.addr_limit.seg) /* * Test whether a block of memory is a valid user space address. * Returns 0 if the range is valid, nonzero otherwise. */ static inline bool __chk_range_not_ok(unsigned long addr, unsigned long size, unsigned long limit) { /* * If we have used "sizeof()" for the size, * we know it won't overflow the limit (but * it might overflow the 'addr', so it's * important to subtract the size from the * limit, not add it to the address). */ if (__builtin_constant_p(size)) return unlikely(addr > limit - size); /* Arbitrary sizes? Be careful about overflow */ addr += size; if (unlikely(addr < size)) return true; return unlikely(addr > limit); } #define __range_not_ok(addr, size, limit) \ ({ \ __chk_user_ptr(addr); \ __chk_range_not_ok((unsigned long __force)(addr), size, limit); \ }) #ifdef CONFIG_DEBUG_ATOMIC_SLEEP # define WARN_ON_IN_IRQ() WARN_ON_ONCE(!in_task()) #else # define WARN_ON_IN_IRQ() #endif /** * access_ok - Checks if a user space pointer is valid * @addr: User space pointer to start of block to check * @size: Size of block to check * * Context: User context only. This function may sleep if pagefaults are * enabled. * * Checks if a pointer to a block of memory in user space is valid. * * Note that, depending on architecture, this function probably just * checks that the pointer is in the user space range - after calling * this function, memory access functions may still return -EFAULT. * * Return: true (nonzero) if the memory block may be valid, false (zero) * if it is definitely invalid. */ #define access_ok(addr, size) \ ({ \ WARN_ON_IN_IRQ(); \ likely(!__range_not_ok(addr, size, user_addr_max())); \ }) /* * These are the main single-value transfer routines. They automatically * use the right size if we just have the right pointer type. * * This gets kind of ugly. We want to return _two_ values in "get_user()" * and yet we don't want to do any pointers, because that is too much * of a performance impact. Thus we have a few rather ugly macros here, * and hide all the ugliness from the user. * * The "__xxx" versions of the user access functions are versions that * do not verify the address space, that must have been done previously * with a separate "access_ok()" call (this is used when we do multiple * accesses to the same area of user memory). */ extern int __get_user_1(void); extern int __get_user_2(void); extern int __get_user_4(void); extern int __get_user_8(void); extern int __get_user_bad(void); #define __uaccess_begin() stac() #define __uaccess_end() clac() #define __uaccess_begin_nospec() \ ({ \ stac(); \ barrier_nospec(); \ }) /* * This is a type: either unsigned long, if the argument fits into * that type, or otherwise unsigned long long. */ #define __inttype(x) \ __typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL)) /** * get_user - Get a simple variable from user space. * @x: Variable to store result. * @ptr: Source address, in user space. * * Context: User context only. This function may sleep if pagefaults are * enabled. * * This macro copies a single simple variable from user space to kernel * space. It supports simple types like char and int, but not larger * data types like structures or arrays. * * @ptr must have pointer-to-simple-variable type, and the result of * dereferencing @ptr must be assignable to @x without a cast. * * Return: zero on success, or -EFAULT on error. * On error, the variable @x is set to zero. */ /* * Careful: we have to cast the result to the type of the pointer * for sign reasons. * * The use of _ASM_DX as the register specifier is a bit of a * simplification, as gcc only cares about it as the starting point * and not size: for a 64-bit value it will use %ecx:%edx on 32 bits * (%ecx being the next register in gcc's x86 register sequence), and * %rdx on 64 bits. * * Clang/LLVM cares about the size of the register, but still wants * the base register for something that ends up being a pair. */ #define get_user(x, ptr) \ ({ \ int __ret_gu; \ register __inttype(*(ptr)) __val_gu asm("%"_ASM_DX); \ __chk_user_ptr(ptr); \ might_fault(); \ asm volatile("call __get_user_%P4" \ : "=a" (__ret_gu), "=r" (__val_gu), \ ASM_CALL_CONSTRAINT \ : "0" (ptr), "i" (sizeof(*(ptr)))); \ (x) = (__force __typeof__(*(ptr))) __val_gu; \ __builtin_expect(__ret_gu, 0); \ }) #define __put_user_x(size, x, ptr, __ret_pu) \ asm volatile("call __put_user_" #size : "=a" (__ret_pu) \ : "0" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx") #ifdef CONFIG_X86_32 #define __put_user_goto_u64(x, addr, label) \ asm_volatile_goto("\n" \ "1: movl %%eax,0(%1)\n" \ "2: movl %%edx,4(%1)\n" \ _ASM_EXTABLE_UA(1b, %l2) \ _ASM_EXTABLE_UA(2b, %l2) \ : : "A" (x), "r" (addr) \ : : label) #define __put_user_asm_ex_u64(x, addr) \ asm volatile("\n" \ "1: movl %%eax,0(%1)\n" \ "2: movl %%edx,4(%1)\n" \ "3:" \ _ASM_EXTABLE_EX(1b, 2b) \ _ASM_EXTABLE_EX(2b, 3b) \ : : "A" (x), "r" (addr)) #define __put_user_x8(x, ptr, __ret_pu) \ asm volatile("call __put_user_8" : "=a" (__ret_pu) \ : "A" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx") #else #define __put_user_goto_u64(x, ptr, label) \ __put_user_goto(x, ptr, "q", "", "er", label) #define __put_user_asm_ex_u64(x, addr) \ __put_user_asm_ex(x, addr, "q", "", "er") #define __put_user_x8(x, ptr, __ret_pu) __put_user_x(8, x, ptr, __ret_pu) #endif extern void __put_user_bad(void); /* * Strange magic calling convention: pointer in %ecx, * value in %eax(:%edx), return value in %eax. clobbers %rbx */ extern void __put_user_1(void); extern void __put_user_2(void); extern void __put_user_4(void); extern void __put_user_8(void); /** * put_user - Write a simple value into user space. * @x: Value to copy to user space. * @ptr: Destination address, in user space. * * Context: User context only. This function may sleep if pagefaults are * enabled. * * This macro copies a single simple value from kernel space to user * space. It supports simple types like char and int, but not larger * data types like structures or arrays. * * @ptr must have pointer-to-simple-variable type, and @x must be assignable * to the result of dereferencing @ptr. * * Return: zero on success, or -EFAULT on error. */ #define put_user(x, ptr) \ ({ \ int __ret_pu; \ __typeof__(*(ptr)) __pu_val; \ __chk_user_ptr(ptr); \ might_fault(); \ __pu_val = x; \ switch (sizeof(*(ptr))) { \ case 1: \ __put_user_x(1, __pu_val, ptr, __ret_pu); \ break; \ case 2: \ __put_user_x(2, __pu_val, ptr, __ret_pu); \ break; \ case 4: \ __put_user_x(4, __pu_val, ptr, __ret_pu); \ break; \ case 8: \ __put_user_x8(__pu_val, ptr, __ret_pu); \ break; \ default: \ __put_user_x(X, __pu_val, ptr, __ret_pu); \ break; \ } \ __builtin_expect(__ret_pu, 0); \ }) #define __put_user_size(x, ptr, size, label) \ do { \ __chk_user_ptr(ptr); \ switch (size) { \ case 1: \ __put_user_goto(x, ptr, "b", "b", "iq", label); \ break; \ case 2: \ __put_user_goto(x, ptr, "w", "w", "ir", label); \ break; \ case 4: \ __put_user_goto(x, ptr, "l", "k", "ir", label); \ break; \ case 8: \ __put_user_goto_u64(x, ptr, label); \ break; \ default: \ __put_user_bad(); \ } \ } while (0) /* * This doesn't do __uaccess_begin/end - the exception handling * around it must do that. */ #define __put_user_size_ex(x, ptr, size) \ do { \ __chk_user_ptr(ptr); \ switch (size) { \ case 1: \ __put_user_asm_ex(x, ptr, "b", "b", "iq"); \ break; \ case 2: \ __put_user_asm_ex(x, ptr, "w", "w", "ir"); \ break; \ case 4: \ __put_user_asm_ex(x, ptr, "l", "k", "ir"); \ break; \ case 8: \ __put_user_asm_ex_u64((__typeof__(*ptr))(x), ptr); \ break; \ default: \ __put_user_bad(); \ } \ } while (0) #ifdef CONFIG_X86_32 #define __get_user_asm_u64(x, ptr, retval, errret) \ ({ \ __typeof__(ptr) __ptr = (ptr); \ asm volatile("\n" \ "1: movl %2,%%eax\n" \ "2: movl %3,%%edx\n" \ "3:\n" \ ".section .fixup,\"ax\"\n" \ "4: mov %4,%0\n" \ " xorl %%eax,%%eax\n" \ " xorl %%edx,%%edx\n" \ " jmp 3b\n" \ ".previous\n" \ _ASM_EXTABLE_UA(1b, 4b) \ _ASM_EXTABLE_UA(2b, 4b) \ : "=r" (retval), "=&A"(x) \ : "m" (__m(__ptr)), "m" __m(((u32 __user *)(__ptr)) + 1), \ "i" (errret), "0" (retval)); \ }) #define __get_user_asm_ex_u64(x, ptr) (x) = __get_user_bad() #else #define __get_user_asm_u64(x, ptr, retval, errret) \ __get_user_asm(x, ptr, retval, "q", "", "=r", errret) #define __get_user_asm_ex_u64(x, ptr) \ __get_user_asm_ex(x, ptr, "q", "", "=r") #endif #define __get_user_size(x, ptr, size, retval, errret) \ do { \ retval = 0; \ __chk_user_ptr(ptr); \ switch (size) { \ case 1: \ __get_user_asm(x, ptr, retval, "b", "b", "=q", errret); \ break; \ case 2: \ __get_user_asm(x, ptr, retval, "w", "w", "=r", errret); \ break; \ case 4: \ __get_user_asm(x, ptr, retval, "l", "k", "=r", errret); \ break; \ case 8: \ __get_user_asm_u64(x, ptr, retval, errret); \ break; \ default: \ (x) = __get_user_bad(); \ } \ } while (0) #define __get_user_asm(x, addr, err, itype, rtype, ltype, errret) \ asm volatile("\n" \ "1: mov"itype" %2,%"rtype"1\n" \ "2:\n" \ ".section .fixup,\"ax\"\n" \ "3: mov %3,%0\n" \ " xor"itype" %"rtype"1,%"rtype"1\n" \ " jmp 2b\n" \ ".previous\n" \ _ASM_EXTABLE_UA(1b, 3b) \ : "=r" (err), ltype(x) \ : "m" (__m(addr)), "i" (errret), "0" (err)) #define __get_user_asm_nozero(x, addr, err, itype, rtype, ltype, errret) \ asm volatile("\n" \ "1: mov"itype" %2,%"rtype"1\n" \ "2:\n" \ ".section .fixup,\"ax\"\n" \ "3: mov %3,%0\n" \ " jmp 2b\n" \ ".previous\n" \ _ASM_EXTABLE_UA(1b, 3b) \ : "=r" (err), ltype(x) \ : "m" (__m(addr)), "i" (errret), "0" (err)) /* * This doesn't do __uaccess_begin/end - the exception handling * around it must do that. */ #define __get_user_size_ex(x, ptr, size) \ do { \ __chk_user_ptr(ptr); \ switch (size) { \ case 1: \ __get_user_asm_ex(x, ptr, "b", "b", "=q"); \ break; \ case 2: \ __get_user_asm_ex(x, ptr, "w", "w", "=r"); \ break; \ case 4: \ __get_user_asm_ex(x, ptr, "l", "k", "=r"); \ break; \ case 8: \ __get_user_asm_ex_u64(x, ptr); \ break; \ default: \ (x) = __get_user_bad(); \ } \ } while (0) #define __get_user_asm_ex(x, addr, itype, rtype, ltype) \ asm volatile("1: mov"itype" %1,%"rtype"0\n" \ "2:\n" \ ".section .fixup,\"ax\"\n" \ "3:xor"itype" %"rtype"0,%"rtype"0\n" \ " jmp 2b\n" \ ".previous\n" \ _ASM_EXTABLE_EX(1b, 3b) \ : ltype(x) : "m" (__m(addr))) #define __put_user_nocheck(x, ptr, size) \ ({ \ __label__ __pu_label; \ int __pu_err = -EFAULT; \ __typeof__(*(ptr)) __pu_val; \ __pu_val = x; \ __uaccess_begin(); \ __put_user_size(__pu_val, (ptr), (size), __pu_label); \ __pu_err = 0; \ __pu_label: \ __uaccess_end(); \ __builtin_expect(__pu_err, 0); \ }) #define __get_user_nocheck(x, ptr, size) \ ({ \ int __gu_err; \ __inttype(*(ptr)) __gu_val; \ __uaccess_begin_nospec(); \ __get_user_size(__gu_val, (ptr), (size), __gu_err, -EFAULT); \ __uaccess_end(); \ (x) = (__force __typeof__(*(ptr)))__gu_val; \ __builtin_expect(__gu_err, 0); \ }) /* FIXME: this hack is definitely wrong -AK */ struct __large_struct { unsigned long buf[100]; }; #define __m(x) (*(struct __large_struct __user *)(x)) /* * Tell gcc we read from memory instead of writing: this is because * we do not write to any memory gcc knows about, so there are no * aliasing issues. */ #define __put_user_goto(x, addr, itype, rtype, ltype, label) \ asm_volatile_goto("\n" \ "1: mov"itype" %"rtype"0,%1\n" \ _ASM_EXTABLE_UA(1b, %l2) \ : : ltype(x), "m" (__m(addr)) \ : : label) #define __put_user_failed(x, addr, itype, rtype, ltype, errret) \ ({ __label__ __puflab; \ int __pufret = errret; \ __put_user_goto(x,addr,itype,rtype,ltype,__puflab); \ __pufret = 0; \ __puflab: __pufret; }) #define __put_user_asm(x, addr, retval, itype, rtype, ltype, errret) do { \ retval = __put_user_failed(x, addr, itype, rtype, ltype, errret); \ } while (0) #define __put_user_asm_ex(x, addr, itype, rtype, ltype) \ asm volatile("1: mov"itype" %"rtype"0,%1\n" \ "2:\n" \ _ASM_EXTABLE_EX(1b, 2b) \ : : ltype(x), "m" (__m(addr))) /* * uaccess_try and catch */ #define uaccess_try do { \ current->thread.uaccess_err = 0; \ __uaccess_begin(); \ barrier(); #define uaccess_try_nospec do { \ current->thread.uaccess_err = 0; \ __uaccess_begin_nospec(); \ #define uaccess_catch(err) \ __uaccess_end(); \ (err) |= (current->thread.uaccess_err ? -EFAULT : 0); \ } while (0) /** * __get_user - Get a simple variable from user space, with less checking. * @x: Variable to store result. * @ptr: Source address, in user space. * * Context: User context only. This function may sleep if pagefaults are * enabled. * * This macro copies a single simple variable from user space to kernel * space. It supports simple types like char and int, but not larger * data types like structures or arrays. * * @ptr must have pointer-to-simple-variable type, and the result of * dereferencing @ptr must be assignable to @x without a cast. * * Caller must check the pointer with access_ok() before calling this * function. * * Return: zero on success, or -EFAULT on error. * On error, the variable @x is set to zero. */ #define __get_user(x, ptr) \ __get_user_nocheck((x), (ptr), sizeof(*(ptr))) /** * __put_user - Write a simple value into user space, with less checking. * @x: Value to copy to user space. * @ptr: Destination address, in user space. * * Context: User context only. This function may sleep if pagefaults are * enabled. * * This macro copies a single simple value from kernel space to user * space. It supports simple types like char and int, but not larger * data types like structures or arrays. * * @ptr must have pointer-to-simple-variable type, and @x must be assignable * to the result of dereferencing @ptr. * * Caller must check the pointer with access_ok() before calling this * function. * * Return: zero on success, or -EFAULT on error. */ #define __put_user(x, ptr) \ __put_user_nocheck((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr))) /* * {get|put}_user_try and catch * * get_user_try { * get_user_ex(...); * } get_user_catch(err) */ #define get_user_try uaccess_try_nospec #define get_user_catch(err) uaccess_catch(err) #define get_user_ex(x, ptr) do { \ unsigned long __gue_val; \ __get_user_size_ex((__gue_val), (ptr), (sizeof(*(ptr)))); \ (x) = (__force __typeof__(*(ptr)))__gue_val; \ } while (0) #define put_user_try uaccess_try #define put_user_catch(err) uaccess_catch(err) #define put_user_ex(x, ptr) \ __put_user_size_ex((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr))) extern unsigned long copy_from_user_nmi(void *to, const void __user *from, unsigned long n); extern __must_check long strncpy_from_user(char *dst, const char __user *src, long count); extern __must_check long strnlen_user(const char __user *str, long n); unsigned long __must_check clear_user(void __user *mem, unsigned long len); unsigned long __must_check __clear_user(void __user *mem, unsigned long len); extern void __cmpxchg_wrong_size(void) __compiletime_error("Bad argument size for cmpxchg"); #define __user_atomic_cmpxchg_inatomic(uval, ptr, old, new, size) \ ({ \ int __ret = 0; \ __typeof__(ptr) __uval = (uval); \ __typeof__(*(ptr)) __old = (old); \ __typeof__(*(ptr)) __new = (new); \ __uaccess_begin_nospec(); \ switch (size) { \ case 1: \ { \ asm volatile("\n" \ "1:\t" LOCK_PREFIX "cmpxchgb %4, %2\n" \ "2:\n" \ "\t.section .fixup, \"ax\"\n" \ "3:\tmov %3, %0\n" \ "\tjmp 2b\n" \ "\t.previous\n" \ _ASM_EXTABLE_UA(1b, 3b) \ : "+r" (__ret), "=a" (__old), "+m" (*(ptr)) \ : "i" (-EFAULT), "q" (__new), "1" (__old) \ : "memory" \ ); \ break; \ } \ case 2: \ { \ asm volatile("\n" \ "1:\t" LOCK_PREFIX "cmpxchgw %4, %2\n" \ "2:\n" \ "\t.section .fixup, \"ax\"\n" \ "3:\tmov %3, %0\n" \ "\tjmp 2b\n" \ "\t.previous\n" \ _ASM_EXTABLE_UA(1b, 3b) \ : "+r" (__ret), "=a" (__old), "+m" (*(ptr)) \ : "i" (-EFAULT), "r" (__new), "1" (__old) \ : "memory" \ ); \ break; \ } \ case 4: \ { \ asm volatile("\n" \ "1:\t" LOCK_PREFIX "cmpxchgl %4, %2\n" \ "2:\n" \ "\t.section .fixup, \"ax\"\n" \ "3:\tmov %3, %0\n" \ "\tjmp 2b\n" \ "\t.previous\n" \ _ASM_EXTABLE_UA(1b, 3b) \ : "+r" (__ret), "=a" (__old), "+m" (*(ptr)) \ : "i" (-EFAULT), "r" (__new), "1" (__old) \ : "memory" \ ); \ break; \ } \ case 8: \ { \ if (!IS_ENABLED(CONFIG_X86_64)) \ __cmpxchg_wrong_size(); \ \ asm volatile("\n" \ "1:\t" LOCK_PREFIX "cmpxchgq %4, %2\n" \ "2:\n" \ "\t.section .fixup, \"ax\"\n" \ "3:\tmov %3, %0\n" \ "\tjmp 2b\n" \ "\t.previous\n" \ _ASM_EXTABLE_UA(1b, 3b) \ : "+r" (__ret), "=a" (__old), "+m" (*(ptr)) \ : "i" (-EFAULT), "r" (__new), "1" (__old) \ : "memory" \ ); \ break; \ } \ default: \ __cmpxchg_wrong_size(); \ } \ __uaccess_end(); \ *__uval = __old; \ __ret; \ }) #define user_atomic_cmpxchg_inatomic(uval, ptr, old, new) \ ({ \ access_ok((ptr), sizeof(*(ptr))) ? \ __user_atomic_cmpxchg_inatomic((uval), (ptr), \ (old), (new), sizeof(*(ptr))) : \ -EFAULT; \ }) /* * movsl can be slow when source and dest are not both 8-byte aligned */ #ifdef CONFIG_X86_INTEL_USERCOPY extern struct movsl_mask { int mask; } ____cacheline_aligned_in_smp movsl_mask; #endif #define ARCH_HAS_NOCACHE_UACCESS 1 #ifdef CONFIG_X86_32 # include #else # include #endif /* * We rely on the nested NMI work to allow atomic faults from the NMI path; the * nested NMI paths are careful to preserve CR2. * * Caller must use pagefault_enable/disable, or run in interrupt context, * and also do a uaccess_ok() check */ #define __copy_from_user_nmi __copy_from_user_inatomic /* * The "unsafe" user accesses aren't really "unsafe", but the naming * is a big fat warning: you have to not only do the access_ok() * checking before using them, but you have to surround them with the * user_access_begin/end() pair. */ static __must_check inline bool user_access_begin(const void __user *ptr, size_t len) { if (unlikely(!access_ok(ptr,len))) return 0; __uaccess_begin_nospec(); return 1; } #define user_access_begin(a,b) user_access_begin(a,b) #define user_access_end() __uaccess_end() #define unsafe_put_user(x, ptr, label) \ __put_user_size((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)), label) #define unsafe_get_user(x, ptr, err_label) \ do { \ int __gu_err; \ __inttype(*(ptr)) __gu_val; \ __get_user_size(__gu_val, (ptr), sizeof(*(ptr)), __gu_err, -EFAULT); \ (x) = (__force __typeof__(*(ptr)))__gu_val; \ if (unlikely(__gu_err)) goto err_label; \ } while (0) #endif /* _ASM_X86_UACCESS_H */