From 12700c17fc286149324f92d6d380bc48e43f253d Mon Sep 17 00:00:00 2001 From: Arnd Bergmann Date: Tue, 15 Feb 2022 17:55:04 +0100 Subject: uaccess: generalize access_ok() There are many different ways that access_ok() is defined across architectures, but in the end, they all just compare against the user_addr_max() value or they accept anything. Provide one definition that works for most architectures, checking against TASK_SIZE_MAX for user processes or skipping the check inside of uaccess_kernel() sections. For architectures without CONFIG_SET_FS(), this should be the fastest check, as it comes down to a single comparison of a pointer against a compile-time constant, while the architecture specific versions tend to do something more complex for historic reasons or get something wrong. Type checking for __user annotations is handled inconsistently across architectures, but this is easily simplified as well by using an inline function that takes a 'const void __user *' argument. A handful of callers need an extra __user annotation for this. Some architectures had trick to use 33-bit or 65-bit arithmetic on the addresses to calculate the overflow, however this simpler version uses fewer registers, which means it can produce better object code in the end despite needing a second (statically predicted) branch. Reviewed-by: Christoph Hellwig Acked-by: Mark Rutland [arm64, asm-generic] Acked-by: Geert Uytterhoeven Acked-by: Stafford Horne Acked-by: Dinh Nguyen Signed-off-by: Arnd Bergmann --- arch/alpha/include/asm/uaccess.h | 34 +++++----------------------------- 1 file changed, 5 insertions(+), 29 deletions(-) (limited to 'arch/alpha/include/asm/uaccess.h') diff --git a/arch/alpha/include/asm/uaccess.h b/arch/alpha/include/asm/uaccess.h index 1b6f25efa247..82c5743fc9cd 100644 --- a/arch/alpha/include/asm/uaccess.h +++ b/arch/alpha/include/asm/uaccess.h @@ -20,28 +20,7 @@ #define get_fs() (current_thread_info()->addr_limit) #define set_fs(x) (current_thread_info()->addr_limit = (x)) -#define uaccess_kernel() (get_fs().seg == KERNEL_DS.seg) - -/* - * Is a address valid? This does a straightforward calculation rather - * than tests. - * - * Address valid if: - * - "addr" doesn't have any high-bits set - * - AND "size" doesn't have any high-bits set - * - AND "addr+size-(size != 0)" doesn't have any high-bits set - * - OR we are in kernel mode. - */ -#define __access_ok(addr, size) ({ \ - unsigned long __ao_a = (addr), __ao_b = (size); \ - unsigned long __ao_end = __ao_a + __ao_b - !!__ao_b; \ - (get_fs().seg & (__ao_a | __ao_b | __ao_end)) == 0; }) - -#define access_ok(addr, size) \ -({ \ - __chk_user_ptr(addr); \ - __access_ok(((unsigned long)(addr)), (size)); \ -}) +#include /* * These are the main single-value transfer routines. They automatically @@ -105,7 +84,7 @@ extern void __get_user_unknown(void); long __gu_err = -EFAULT; \ unsigned long __gu_val = 0; \ const __typeof__(*(ptr)) __user *__gu_addr = (ptr); \ - if (__access_ok((unsigned long)__gu_addr, size)) { \ + if (__access_ok(__gu_addr, size)) { \ __gu_err = 0; \ switch (size) { \ case 1: __get_user_8(__gu_addr); break; \ @@ -200,7 +179,7 @@ extern void __put_user_unknown(void); ({ \ long __pu_err = -EFAULT; \ __typeof__(*(ptr)) __user *__pu_addr = (ptr); \ - if (__access_ok((unsigned long)__pu_addr, size)) { \ + if (__access_ok(__pu_addr, size)) { \ __pu_err = 0; \ switch (size) { \ case 1: __put_user_8(x, __pu_addr); break; \ @@ -316,17 +295,14 @@ raw_copy_to_user(void __user *to, const void *from, unsigned long len) extern long __clear_user(void __user *to, long len); -extern inline long +static inline long clear_user(void __user *to, long len) { - if (__access_ok((unsigned long)to, len)) + if (__access_ok(to, len)) len = __clear_user(to, len); return len; } -#define user_addr_max() \ - (uaccess_kernel() ? ~0UL : TASK_SIZE) - 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); -- cgit v1.2.3-59-g8ed1b