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Diffstat (limited to 'arch/arm/include/asm/uaccess.h')
-rw-r--r--arch/arm/include/asm/uaccess.h132
1 files changed, 92 insertions, 40 deletions
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
@@ -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; \
})
@@ -300,20 +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);
generated by cgit v1.2.3-54-g00ecf (git 2.45.2) at 2024-11-11 14:13:46 +0000