diff options
Diffstat (limited to 'arch/arm/include/asm/uaccess.h')
| -rw-r--r-- | arch/arm/include/asm/uaccess.h | 85 |
1 files changed, 80 insertions, 5 deletions
diff --git a/arch/arm/include/asm/uaccess.h b/arch/arm/include/asm/uaccess.h index 4cf54ebe408a..8cc85a4ebec2 100644 --- a/arch/arm/include/asm/uaccess.h +++ b/arch/arm/include/asm/uaccess.h @@ -50,6 +50,35 @@ struct exception_table_entry extern int fixup_exception(struct pt_regs *regs); /* + * 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 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 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. */ @@ -165,6 +194,7 @@ extern int __get_user_64t_4(void *); register typeof(x) __r2 asm("r2"); \ register unsigned long __l asm("r1") = __limit; \ register int __e asm("r0"); \ + unsigned int __ua_flags = uaccess_save_and_enable(); \ switch (sizeof(*(__p))) { \ case 1: \ if (sizeof((x)) >= 8) \ @@ -192,6 +222,7 @@ extern int __get_user_64t_4(void *); break; \ default: __e = __get_user_bad(); break; \ } \ + uaccess_restore(__ua_flags); \ x = (typeof(*(p))) __r2; \ __e; \ }) @@ -224,6 +255,7 @@ extern int __put_user_8(void *, unsigned long long); register const typeof(*(p)) __user *__p asm("r0") = __tmp_p; \ register unsigned long __l asm("r1") = __limit; \ register int __e asm("r0"); \ + unsigned int __ua_flags = uaccess_save_and_enable(); \ switch (sizeof(*(__p))) { \ case 1: \ __put_user_x(__r2, __p, __e, __l, 1); \ @@ -239,6 +271,7 @@ extern int __put_user_8(void *, unsigned long long); break; \ default: __e = __put_user_bad(); break; \ } \ + uaccess_restore(__ua_flags); \ __e; \ }) @@ -300,14 +333,17 @@ static inline void set_fs(mm_segment_t fs) 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) @@ -369,9 +405,11 @@ do { \ #define __put_user_err(x, ptr, err) \ do { \ unsigned long __pu_addr = (unsigned long)(ptr); \ + unsigned int __ua_flags; \ __typeof__(*(ptr)) __pu_val = (x); \ __chk_user_ptr(ptr); \ might_fault(); \ + __ua_flags = uaccess_save_and_enable(); \ switch (sizeof(*(ptr))) { \ case 1: __put_user_asm_byte(__pu_val, __pu_addr, err); break; \ case 2: __put_user_asm_half(__pu_val, __pu_addr, err); break; \ @@ -379,6 +417,7 @@ do { \ case 8: __put_user_asm_dword(__pu_val, __pu_addr, err); break; \ default: __put_user_bad(); \ } \ + uaccess_restore(__ua_flags); \ } while (0) #define __put_user_asm(x, __pu_addr, err, instr) \ @@ -451,11 +490,46 @@ do { \ #ifdef CONFIG_MMU -extern unsigned long __must_check __copy_from_user(void *to, const void __user *from, unsigned long n); -extern unsigned long __must_check __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); -extern unsigned long __must_check __clear_user(void __user *addr, unsigned long n); -extern unsigned long __must_check __clear_user_std(void __user *addr, unsigned long n); +extern unsigned long __must_check +arm_copy_from_user(void *to, const void __user *from, unsigned long n); + +static inline unsigned long __must_check +__copy_from_user(void *to, const void __user *from, unsigned long n) +{ + unsigned int __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 +__copy_to_user(void __user *to, const void *from, unsigned long n) +{ + unsigned int __ua_flags = uaccess_save_and_enable(); + n = arm_copy_to_user(to, from, n); + uaccess_restore(__ua_flags); + return n; +} + +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 #define __copy_from_user(to, from, n) (memcpy(to, (void __force *)from, n), 0) #define __copy_to_user(to, from, n) (memcpy((void __force *)to, from, n), 0) @@ -488,6 +562,7 @@ static inline unsigned long __must_check clear_user(void __user *to, unsigned lo 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 strlen_user(const char __user *str); |