From 8d91c1e411f55d7ea91b1183a2e9f8088fb4d5be Mon Sep 17 00:00:00 2001 From: André Fabian Silva Delgado Date: Tue, 15 Dec 2015 14:52:16 -0300 Subject: Linux-libre 4.3.2-gnu --- arch/arm/include/asm/uaccess.h | 132 ++++++++++++++++++++++++++++------------- 1 file changed, 92 insertions(+), 40 deletions(-) (limited to 'arch/arm/include/asm/uaccess.h') diff --git a/arch/arm/include/asm/uaccess.h b/arch/arm/include/asm/uaccess.h index 74b17d09e..8cc85a4eb 100644 --- a/arch/arm/include/asm/uaccess.h +++ b/arch/arm/include/asm/uaccess.h @@ -49,6 +49,35 @@ 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; \ }) @@ -300,20 +333,23 @@ 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) -#define __get_user_asm_byte(x, addr, err) \ +#define __get_user_asm(x, addr, err, instr) \ __asm__ __volatile__( \ - "1: " TUSER(ldrb) " %1,[%2],#0\n" \ + "1: " TUSER(instr) " %1, [%2], #0\n" \ "2:\n" \ " .pushsection .text.fixup,\"ax\"\n" \ " .align 2\n" \ @@ -329,6 +365,9 @@ do { \ : "r" (addr), "i" (-EFAULT) \ : "cc") +#define __get_user_asm_byte(x, addr, err) \ + __get_user_asm(x, addr, err, ldrb) + #ifndef __ARMEB__ #define __get_user_asm_half(x, __gu_addr, err) \ ({ \ @@ -348,22 +387,7 @@ do { \ #endif #define __get_user_asm_word(x, addr, err) \ - __asm__ __volatile__( \ - "1: " TUSER(ldr) " %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") + __get_user_asm(x, addr, err, ldr) #define __put_user(x, ptr) \ ({ \ @@ -381,9 +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; \ @@ -391,11 +417,12 @@ 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_byte(x, __pu_addr, err) \ +#define __put_user_asm(x, __pu_addr, err, instr) \ __asm__ __volatile__( \ - "1: " TUSER(strb) " %1,[%2],#0\n" \ + "1: " TUSER(instr) " %1, [%2], #0\n" \ "2:\n" \ " .pushsection .text.fixup,\"ax\"\n" \ " .align 2\n" \ @@ -410,6 +437,9 @@ do { \ : "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) + #ifndef __ARMEB__ #define __put_user_asm_half(x, __pu_addr, err) \ ({ \ @@ -427,21 +457,7 @@ do { \ #endif #define __put_user_asm_word(x, __pu_addr, err) \ - __asm__ __volatile__( \ - "1: " TUSER(str) " %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") + __put_user_asm(x, __pu_addr, err, str) #ifndef __ARMEB__ #define __reg_oper0 "%R2" @@ -474,11 +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) @@ -511,6 +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); -- cgit v1.2.3-54-g00ecf