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Diffstat (limited to 'arch/x86/include/asm/uaccess.h')
| -rw-r--r-- | arch/x86/include/asm/uaccess.h | 555 |
1 files changed, 555 insertions, 0 deletions
diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h new file mode 100644 index 000000000..bf2561a5e --- /dev/null +++ b/arch/x86/include/asm/uaccess.h @@ -0,0 +1,555 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _ASM_X86_UACCESS_H +#define _ASM_X86_UACCESS_H +/* + * User space memory access functions + */ +#include <linux/compiler.h> +#include <linux/kasan-checks.h> +#include <linux/string.h> +#include <asm/asm.h> +#include <asm/page.h> +#include <asm/smap.h> +#include <asm/extable.h> + +/* + * 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 +static inline bool pagefault_disabled(void); +# define WARN_ON_IN_IRQ() \ + WARN_ON_ONCE(!in_task() && !pagefault_disabled()) +#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, TASK_SIZE_MAX)); \ +}) + +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_nocheck_1(void); +extern int __get_user_nocheck_2(void); +extern int __get_user_nocheck_4(void); +extern int __get_user_nocheck_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 the smallest unsigned integer type that can fit a value + * (up to 'long long') + */ +#define __inttype(x) __typeof__( \ + __typefits(x,char, \ + __typefits(x,short, \ + __typefits(x,int, \ + __typefits(x,long,0ULL))))) + +#define __typefits(x,type,not) \ + __builtin_choose_expr(sizeof(x)<=sizeof(type),(unsigned type)0,not) + +/* + * This is used for both get_user() and __get_user() to expand to + * the proper special function call that has odd calling conventions + * due to returning both a value and an error, and that depends on + * the size of the pointer passed in. + * + * 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 do_get_user_call(fn,x,ptr) \ +({ \ + int __ret_gu; \ + register __inttype(*(ptr)) __val_gu asm("%"_ASM_DX); \ + __chk_user_ptr(ptr); \ + asm volatile("call __" #fn "_%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); \ +}) + +/** + * 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. + */ +#define get_user(x,ptr) ({ might_fault(); do_get_user_call(get_user,x,ptr); }) + +/** + * __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) do_get_user_call(get_user_nocheck,x,ptr) + + +#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) + +#else +#define __put_user_goto_u64(x, ptr, label) \ + __put_user_goto(x, ptr, "q", "er", label) +#endif + +extern void __put_user_bad(void); + +/* + * Strange magic calling convention: pointer in %ecx, + * value in %eax(:%edx), return value in %ecx. 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); +extern void __put_user_nocheck_1(void); +extern void __put_user_nocheck_2(void); +extern void __put_user_nocheck_4(void); +extern void __put_user_nocheck_8(void); + +/* + * ptr must be evaluated and assigned to the temporary __ptr_pu before + * the assignment of x to __val_pu, to avoid any function calls + * involved in the ptr expression (possibly implicitly generated due + * to KASAN) from clobbering %ax. + */ +#define do_put_user_call(fn,x,ptr) \ +({ \ + int __ret_pu; \ + void __user *__ptr_pu; \ + register __typeof__(*(ptr)) __val_pu asm("%"_ASM_AX); \ + __chk_user_ptr(ptr); \ + __ptr_pu = (ptr); \ + __val_pu = (x); \ + asm volatile("call __" #fn "_%P[size]" \ + : "=c" (__ret_pu), \ + ASM_CALL_CONSTRAINT \ + : "0" (__ptr_pu), \ + "r" (__val_pu), \ + [size] "i" (sizeof(*(ptr))) \ + :"ebx"); \ + __builtin_expect(__ret_pu, 0); \ +}) + +/** + * 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) ({ might_fault(); do_put_user_call(put_user,x,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) do_put_user_call(put_user_nocheck,x,ptr) + +#define __put_user_size(x, ptr, size, label) \ +do { \ + __chk_user_ptr(ptr); \ + switch (size) { \ + case 1: \ + __put_user_goto(x, ptr, "b", "iq", label); \ + break; \ + case 2: \ + __put_user_goto(x, ptr, "w", "ir", label); \ + break; \ + case 4: \ + __put_user_goto(x, ptr, "l", "ir", label); \ + break; \ + case 8: \ + __put_user_goto_u64(x, ptr, label); \ + break; \ + default: \ + __put_user_bad(); \ + } \ +} while (0) + +#ifdef CONFIG_CC_HAS_ASM_GOTO_OUTPUT + +#ifdef CONFIG_X86_32 +#define __get_user_asm_u64(x, ptr, label) do { \ + unsigned int __gu_low, __gu_high; \ + const unsigned int __user *__gu_ptr; \ + __gu_ptr = (const void __user *)(ptr); \ + __get_user_asm(__gu_low, __gu_ptr, "l", "=r", label); \ + __get_user_asm(__gu_high, __gu_ptr+1, "l", "=r", label); \ + (x) = ((unsigned long long)__gu_high << 32) | __gu_low; \ +} while (0) +#else +#define __get_user_asm_u64(x, ptr, label) \ + __get_user_asm(x, ptr, "q", "=r", label) +#endif + +#define __get_user_size(x, ptr, size, label) \ +do { \ + __chk_user_ptr(ptr); \ + switch (size) { \ + case 1: { \ + unsigned char x_u8__; \ + __get_user_asm(x_u8__, ptr, "b", "=q", label); \ + (x) = x_u8__; \ + break; \ + } \ + case 2: \ + __get_user_asm(x, ptr, "w", "=r", label); \ + break; \ + case 4: \ + __get_user_asm(x, ptr, "l", "=r", label); \ + break; \ + case 8: \ + __get_user_asm_u64(x, ptr, label); \ + break; \ + default: \ + (x) = __get_user_bad(); \ + } \ +} while (0) + +#define __get_user_asm(x, addr, itype, ltype, label) \ + asm_volatile_goto("\n" \ + "1: mov"itype" %[umem],%[output]\n" \ + _ASM_EXTABLE_UA(1b, %l2) \ + : [output] ltype(x) \ + : [umem] "m" (__m(addr)) \ + : : label) + +#else // !CONFIG_CC_HAS_ASM_GOTO_OUTPUT + +#ifdef CONFIG_X86_32 +#define __get_user_asm_u64(x, ptr, retval) \ +({ \ + __typeof__(ptr) __ptr = (ptr); \ + asm volatile("\n" \ + "1: movl %[lowbits],%%eax\n" \ + "2: movl %[highbits],%%edx\n" \ + "3:\n" \ + ".section .fixup,\"ax\"\n" \ + "4: mov %[efault],%[errout]\n" \ + " xorl %%eax,%%eax\n" \ + " xorl %%edx,%%edx\n" \ + " jmp 3b\n" \ + ".previous\n" \ + _ASM_EXTABLE_UA(1b, 4b) \ + _ASM_EXTABLE_UA(2b, 4b) \ + : [errout] "=r" (retval), \ + [output] "=&A"(x) \ + : [lowbits] "m" (__m(__ptr)), \ + [highbits] "m" __m(((u32 __user *)(__ptr)) + 1), \ + [efault] "i" (-EFAULT), "0" (retval)); \ +}) + +#else +#define __get_user_asm_u64(x, ptr, retval) \ + __get_user_asm(x, ptr, retval, "q", "=r") +#endif + +#define __get_user_size(x, ptr, size, retval) \ +do { \ + unsigned char x_u8__; \ + \ + retval = 0; \ + __chk_user_ptr(ptr); \ + switch (size) { \ + case 1: \ + __get_user_asm(x_u8__, ptr, retval, "b", "=q"); \ + (x) = x_u8__; \ + break; \ + case 2: \ + __get_user_asm(x, ptr, retval, "w", "=r"); \ + break; \ + case 4: \ + __get_user_asm(x, ptr, retval, "l", "=r"); \ + break; \ + case 8: \ + __get_user_asm_u64(x, ptr, retval); \ + break; \ + default: \ + (x) = __get_user_bad(); \ + } \ +} while (0) + +#define __get_user_asm(x, addr, err, itype, ltype) \ + asm volatile("\n" \ + "1: mov"itype" %[umem],%[output]\n" \ + "2:\n" \ + ".section .fixup,\"ax\"\n" \ + "3: mov %[efault],%[errout]\n" \ + " xorl %k[output],%k[output]\n" \ + " jmp 2b\n" \ + ".previous\n" \ + _ASM_EXTABLE_UA(1b, 3b) \ + : [errout] "=r" (err), \ + [output] ltype(x) \ + : [umem] "m" (__m(addr)), \ + [efault] "i" (-EFAULT), "0" (err)) + +#endif // CONFIG_CC_ASM_GOTO_OUTPUT + +/* 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, ltype, label) \ + asm_volatile_goto("\n" \ + "1: mov"itype" %0,%1\n" \ + _ASM_EXTABLE_UA(1b, %l2) \ + : : ltype(x), "m" (__m(addr)) \ + : : label) + +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); + +#ifdef CONFIG_ARCH_HAS_COPY_MC +unsigned long __must_check +copy_mc_to_kernel(void *to, const void *from, unsigned len); +#define copy_mc_to_kernel copy_mc_to_kernel + +unsigned long __must_check +copy_mc_to_user(void __user *to, const void *from, unsigned len); +#endif + +/* + * 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 <asm/uaccess_32.h> +#else +# include <asm/uaccess_64.h> +#endif + +/* + * 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 __always_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 user_access_save() smap_save() +#define user_access_restore(x) smap_restore(x) + +#define unsafe_put_user(x, ptr, label) \ + __put_user_size((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)), label) + +#ifdef CONFIG_CC_HAS_ASM_GOTO_OUTPUT +#define unsafe_get_user(x, ptr, err_label) \ +do { \ + __inttype(*(ptr)) __gu_val; \ + __get_user_size(__gu_val, (ptr), sizeof(*(ptr)), err_label); \ + (x) = (__force __typeof__(*(ptr)))__gu_val; \ +} while (0) +#else // !CONFIG_CC_HAS_ASM_GOTO_OUTPUT +#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); \ + (x) = (__force __typeof__(*(ptr)))__gu_val; \ + if (unlikely(__gu_err)) goto err_label; \ +} while (0) +#endif // CONFIG_CC_HAS_ASM_GOTO_OUTPUT + +/* + * We want the unsafe accessors to always be inlined and use + * the error labels - thus the macro games. + */ +#define unsafe_copy_loop(dst, src, len, type, label) \ + while (len >= sizeof(type)) { \ + unsafe_put_user(*(type *)(src),(type __user *)(dst),label); \ + dst += sizeof(type); \ + src += sizeof(type); \ + len -= sizeof(type); \ + } + +#define unsafe_copy_to_user(_dst,_src,_len,label) \ +do { \ + char __user *__ucu_dst = (_dst); \ + const char *__ucu_src = (_src); \ + size_t __ucu_len = (_len); \ + unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u64, label); \ + unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u32, label); \ + unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u16, label); \ + unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u8, label); \ +} while (0) + +#define HAVE_GET_KERNEL_NOFAULT + +#ifdef CONFIG_CC_HAS_ASM_GOTO_OUTPUT +#define __get_kernel_nofault(dst, src, type, err_label) \ + __get_user_size(*((type *)(dst)), (__force type __user *)(src), \ + sizeof(type), err_label) +#else // !CONFIG_CC_HAS_ASM_GOTO_OUTPUT +#define __get_kernel_nofault(dst, src, type, err_label) \ +do { \ + int __kr_err; \ + \ + __get_user_size(*((type *)(dst)), (__force type __user *)(src), \ + sizeof(type), __kr_err); \ + if (unlikely(__kr_err)) \ + goto err_label; \ +} while (0) +#endif // CONFIG_CC_HAS_ASM_GOTO_OUTPUT + +#define __put_kernel_nofault(dst, src, type, err_label) \ + __put_user_size(*((type *)(src)), (__force type __user *)(dst), \ + sizeof(type), err_label) + +#endif /* _ASM_X86_UACCESS_H */ + |