diff options
Diffstat (limited to 'include/asm-generic/access_ok.h')
-rw-r--r-- | include/asm-generic/access_ok.h | 60 |
1 files changed, 60 insertions, 0 deletions
diff --git a/include/asm-generic/access_ok.h b/include/asm-generic/access_ok.h new file mode 100644 index 000000000000..d38cc5dad65b --- /dev/null +++ b/include/asm-generic/access_ok.h @@ -0,0 +1,60 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef __ASM_GENERIC_ACCESS_OK_H__ +#define __ASM_GENERIC_ACCESS_OK_H__ + +/* + * Checking whether a pointer is valid for user space access. + * These definitions work on most architectures, but overrides can + * be used where necessary. + */ + +/* + * architectures with compat tasks have a variable TASK_SIZE and should + * override this to a constant. + */ +#ifndef TASK_SIZE_MAX +#define TASK_SIZE_MAX TASK_SIZE +#endif + +#ifndef uaccess_kernel +#ifdef CONFIG_SET_FS +#define uaccess_kernel() (get_fs().seg == KERNEL_DS.seg) +#else +#define uaccess_kernel() (0) +#endif +#endif + +#ifndef user_addr_max +#define user_addr_max() (uaccess_kernel() ? ~0UL : TASK_SIZE_MAX) +#endif + +#ifndef __access_ok +/* + * 'size' is a compile-time constant for most callers, so optimize for + * this case to turn the check into a single comparison against a constant + * limit and catch all possible overflows. + * On architectures with separate user address space (m68k, s390, parisc, + * sparc64) or those without an MMU, this should always return true. + * + * This version was originally contributed by Jonas Bonn for the + * OpenRISC architecture, and was found to be the most efficient + * for constant 'size' and 'limit' values. + */ +static inline int __access_ok(const void __user *ptr, unsigned long size) +{ + unsigned long limit = user_addr_max(); + unsigned long addr = (unsigned long)ptr; + + if (IS_ENABLED(CONFIG_ALTERNATE_USER_ADDRESS_SPACE) || + !IS_ENABLED(CONFIG_MMU)) + return true; + + return (size <= limit) && (addr <= (limit - size)); +} +#endif + +#ifndef access_ok +#define access_ok(addr, size) likely(__access_ok(addr, size)) +#endif + +#endif |