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Diffstat (limited to 'arch/arm/include/asm/uaccess.h')
| -rw-r--r-- | arch/arm/include/asm/uaccess.h | 595 |
1 files changed, 595 insertions, 0 deletions
diff --git a/arch/arm/include/asm/uaccess.h b/arch/arm/include/asm/uaccess.h new file mode 100644 index 000000000..d9db752c5 --- /dev/null +++ b/arch/arm/include/asm/uaccess.h @@ -0,0 +1,595 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * arch/arm/include/asm/uaccess.h + */ +#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 __always_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 __always_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 + +#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; + + /* + * Prevent a mispredicted conditional call to set_fs from forwarding + * the wrong address limit to access_ok under speculation. + */ + dsb(nsh); + isb(); + + modify_domain(DOMAIN_KERNEL, fs ? DOMAIN_CLIENT : DOMAIN_MANAGER); +} + +#define uaccess_kernel() (get_fs() == KERNEL_DS) + +/* + * We use 33-bit arithmetic here. Success returns zero, failure returns + * addr_limit. We take advantage that addr_limit will be zero for KERNEL_DS, + * so this will always return success in that case. + */ +#define __range_ok(addr, size) ({ \ + unsigned long flag, roksum; \ + __chk_user_ptr(addr); \ + __asm__(".syntax unified\n" \ + "adds %1, %2, %3; sbcscc %1, %1, %0; movcc %0, #0" \ + : "=&r" (flag), "=&r" (roksum) \ + : "r" (addr), "Ir" (size), "0" (current_thread_info()->addr_limit) \ + : "cc"); \ + flag; }) + +/* + * 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)) + +/* + * 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( + " .syntax unified\n" + " sub %1, %3, #1\n" + " subs %1, %1, %0\n" + " addhs %1, %1, #1\n" + " subshs %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 + * 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 typeof(*(p)) __user *__p asm("r0") = (p); \ + register __inttype(x) __r2 asm("r2"); \ + register unsigned long __l asm("r1") = __limit; \ + register int __e asm("r0"); \ + unsigned int __ua_flags = uaccess_save_and_enable(); \ + int __tmp_e; \ + 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; \ + } \ + __tmp_e = __e; \ + uaccess_restore(__ua_flags); \ + x = (typeof(*(p))) __r2; \ + __tmp_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 uaccess_kernel() (true) +#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(addr, size) (__range_ok(addr, size) == 0) + +#define user_addr_max() \ + (uaccess_kernel() ? ~0UL : get_fs()) + +#ifdef CONFIG_CPU_SPECTRE +/* + * When mitigating Spectre variant 1, it is not worth fixing the non- + * verifying accessors, because we need to add verification of the + * address space there. Force these to use the standard get_user() + * version instead. + */ +#define __get_user(x, ptr) get_user(x, ptr) +#else + +/* + * 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_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) + +#if __LINUX_ARM_ARCH__ >= 6 + +#define __get_user_asm_half(x, addr, err) \ + __get_user_asm(x, addr, err, ldrh) + +#else + +#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 + +#endif /* __LINUX_ARM_ARCH__ >= 6 */ + +#define __get_user_asm_word(x, addr, err) \ + __get_user_asm(x, addr, err, ldr) +#endif + + +#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; \ +}) + +#ifdef CONFIG_CPU_SPECTRE +/* + * When mitigating Spectre variant 1.1, all accessors need to include + * verification of the address space. + */ +#define __put_user(x, ptr) put_user(x, ptr) + +#else +#define __put_user(x, ptr) \ +({ \ + long __pu_err = 0; \ + __put_user_switch((x), (ptr), __pu_err, __put_user_nocheck); \ + __pu_err; \ +}) + +#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) + +#if __LINUX_ARM_ARCH__ >= 6 + +#define __put_user_asm_half(x, __pu_addr, err) \ + __put_user_asm(x, __pu_addr, err, strh) + +#else + +#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 + +#endif /* __LINUX_ARM_ARCH__ >= 6 */ + +#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") + +#endif /* !CONFIG_CPU_SPECTRE */ + +#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(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 */ |