cregit-Linux how code gets into the kernel

Release 4.14 arch/powerpc/include/asm/uaccess.h

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _ARCH_POWERPC_UACCESS_H

#define _ARCH_POWERPC_UACCESS_H

#include <asm/asm-compat.h>
#include <asm/ppc_asm.h>
#include <asm/processor.h>
#include <asm/page.h>
#include <asm/extable.h>

/*
 * The fs value determines whether argument validity checking should be
 * performed or not.  If get_fs() == USER_DS, checking is performed, with
 * get_fs() == KERNEL_DS, checking is bypassed.
 *
 * For historical reasons, these macros are grossly misnamed.
 *
 * The fs/ds values are now the highest legal address in the "segment".
 * This simplifies the checking in the routines below.
 */


#define MAKE_MM_SEG(s)  ((mm_segment_t) { (s) })


#define KERNEL_DS	MAKE_MM_SEG(~0UL)
#ifdef __powerpc64__
/* We use TASK_SIZE_USER64 as TASK_SIZE is not constant */

#define USER_DS		MAKE_MM_SEG(TASK_SIZE_USER64 - 1)
#else

#define USER_DS		MAKE_MM_SEG(TASK_SIZE - 1)
#endif


#define get_ds()	(KERNEL_DS)

#define get_fs()	(current->thread.fs)

#define set_fs(val)	(current->thread.fs = (val))


#define segment_eq(a, b)	((a).seg == (b).seg)


#define user_addr_max()	(get_fs().seg)

#ifdef __powerpc64__
/*
 * This check is sufficient because there is a large enough
 * gap between user addresses and the kernel addresses
 */

#define __access_ok(addr, size, segment)	\
	(((addr) <= (segment).seg) && ((size) <= (segment).seg))

#else


#define __access_ok(addr, size, segment)	\
	(((addr) <= (segment).seg) &&           \
         (((size) == 0) || (((size) - 1) <= ((segment).seg - (addr)))))

#endif


#define access_ok(type, addr, size)		\
	(__chk_user_ptr(addr),                  \
         __access_ok((__force unsigned long)(addr), (size), get_fs()))

/*
 * These are the main single-value transfer routines.  They automatically
 * use the right size if we just have the right pointer type.
 *
 * This gets kind of ugly. We want to return _two_ values in "get_user()"
 * and yet we don't want to do any pointers, because that is too much
 * of a performance impact. Thus we have a few rather ugly macros here,
 * and hide all the ugliness from the user.
 *
 * The "__xxx" versions of the user access functions are versions that
 * do not verify the address space, that must have been done previously
 * with a separate "access_ok()" call (this is used when we do multiple
 * accesses to the same area of user memory).
 *
 * As we use the same address space for kernel and user data on the
 * PowerPC, we can just do these as direct assignments.  (Of course, the
 * exception handling means that it's no longer "just"...)
 *
 */

#define get_user(x, ptr) \
	__get_user_check((x), (ptr), sizeof(*(ptr)))

#define put_user(x, ptr) \
	__put_user_check((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))


#define __get_user(x, ptr) \
	__get_user_nocheck((x), (ptr), sizeof(*(ptr)))

#define __put_user(x, ptr) \
	__put_user_nocheck((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))


#define __get_user_inatomic(x, ptr) \
	__get_user_nosleep((x), (ptr), sizeof(*(ptr)))

#define __put_user_inatomic(x, ptr) \
	__put_user_nosleep((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))

extern long __put_user_bad(void);

/*
 * We don't tell gcc that we are accessing memory, but this is OK
 * because we do not write to any memory gcc knows about, so there
 * are no aliasing issues.
 */

#define __put_user_asm(x, addr, err, op)			\
	__asm__ __volatile__(                                   \
                "1:     " op " %1,0(%2) # put_user\n"           \
                "2:\n"                                          \
                ".section .fixup,\"ax\"\n"                      \
                "3:     li %0,%3\n"                             \
                "       b 2b\n"                                 \
                ".previous\n"                                   \
                EX_TABLE(1b, 3b)                                \
                : "=r" (err)                                    \
                : "r" (x), "b" (addr), "i" (-EFAULT), "0" (err))

#ifdef __powerpc64__

#define __put_user_asm2(x, ptr, retval)				\
	  __put_user_asm(x, ptr, retval, "std")
#else /* __powerpc64__ */

#define __put_user_asm2(x, addr, err)				\
	__asm__ __volatile__(                                   \
                "1:     stw %1,0(%2)\n"                         \
                "2:     stw %1+1,4(%2)\n"                       \
                "3:\n"                                          \
                ".section .fixup,\"ax\"\n"                      \
                "4:     li %0,%3\n"                             \
                "       b 3b\n"                                 \
                ".previous\n"                                   \
                EX_TABLE(1b, 4b)                                \
                EX_TABLE(2b, 4b)                                \
                : "=r" (err)                                    \
                : "r" (x), "b" (addr), "i" (-EFAULT), "0" (err))
#endif /* __powerpc64__ */


#define __put_user_size(x, ptr, size, retval)			\
do {                                                            \
        retval = 0;                                             \
        switch (size) {                                         \
          case 1: __put_user_asm(x, ptr, retval, "stb"); break; \
          case 2: __put_user_asm(x, ptr, retval, "sth"); break; \
          case 4: __put_user_asm(x, ptr, retval, "stw"); break; \
          case 8: __put_user_asm2(x, ptr, retval); break;       \
          default: __put_user_bad();                            \
        }                                                       \
} while (0)


#define __put_user_nocheck(x, ptr, size)			\
({                                                              \
        long __pu_err;                                          \
        __typeof__(*(ptr)) __user *__pu_addr = (ptr);           \
        if (!is_kernel_addr((unsigned long)__pu_addr))          \
                might_fault();                                  \
        __chk_user_ptr(ptr);                                    \
        __put_user_size((x), __pu_addr, (size), __pu_err);      \
        __pu_err;                                               \
})


#define __put_user_check(x, ptr, size)					\
({                                                                      \
        long __pu_err = -EFAULT;                                        \
        __typeof__(*(ptr)) __user *__pu_addr = (ptr);                   \
        might_fault();                                                  \
        if (access_ok(VERIFY_WRITE, __pu_addr, size))                   \
                __put_user_size((x), __pu_addr, (size), __pu_err);      \
        __pu_err;                                                       \
})


#define __put_user_nosleep(x, ptr, size)			\
({                                                              \
        long __pu_err;                                          \
        __typeof__(*(ptr)) __user *__pu_addr = (ptr);           \
        __chk_user_ptr(ptr);                                    \
        __put_user_size((x), __pu_addr, (size), __pu_err);      \
        __pu_err;                                               \
})


extern long __get_user_bad(void);


#define __get_user_asm(x, addr, err, op)		\
	__asm__ __volatile__(                           \
                "1:     "op" %1,0(%2)   # get_user\n"   \
                "2:\n"                                  \
                ".section .fixup,\"ax\"\n"              \
                "3:     li %0,%3\n"                     \
                "       li %1,0\n"                      \
                "       b 2b\n"                         \
                ".previous\n"                           \
                EX_TABLE(1b, 3b)                        \
                : "=r" (err), "=r" (x)                  \
                : "b" (addr), "i" (-EFAULT), "0" (err))

#ifdef __powerpc64__

#define __get_user_asm2(x, addr, err)			\
	__get_user_asm(x, addr, err, "ld")
#else /* __powerpc64__ */

#define __get_user_asm2(x, addr, err)			\
	__asm__ __volatile__(                           \
                "1:     lwz %1,0(%2)\n"                 \
                "2:     lwz %1+1,4(%2)\n"               \
                "3:\n"                                  \
                ".section .fixup,\"ax\"\n"              \
                "4:     li %0,%3\n"                     \
                "       li %1,0\n"                      \
                "       li %1+1,0\n"                    \
                "       b 3b\n"                         \
                ".previous\n"                           \
                EX_TABLE(1b, 4b)                        \
                EX_TABLE(2b, 4b)                        \
                : "=r" (err), "=&r" (x)                 \
                : "b" (addr), "i" (-EFAULT), "0" (err))
#endif /* __powerpc64__ */


#define __get_user_size(x, ptr, size, retval)			\
do {                                                            \
        retval = 0;                                             \
        __chk_user_ptr(ptr);                                    \
        if (size > sizeof(x))                                   \
                (x) = __get_user_bad();                         \
        switch (size) {                                         \
        case 1: __get_user_asm(x, ptr, retval, "lbz"); break;   \
        case 2: __get_user_asm(x, ptr, retval, "lhz"); break;   \
        case 4: __get_user_asm(x, ptr, retval, "lwz"); break;   \
        case 8: __get_user_asm2(x, ptr, retval);  break;        \
        default: (x) = __get_user_bad();                        \
        }                                                       \
} while (0)


#define __get_user_nocheck(x, ptr, size)			\
({                                                              \
        long __gu_err;                                          \
        unsigned long __gu_val;                                 \
        const __typeof__(*(ptr)) __user *__gu_addr = (ptr);     \
        __chk_user_ptr(ptr);                                    \
        if (!is_kernel_addr((unsigned long)__gu_addr))          \
                might_fault();                                  \
        __get_user_size(__gu_val, __gu_addr, (size), __gu_err); \
        (x) = (__typeof__(*(ptr)))__gu_val;                     \
        __gu_err;                                               \
})


#define __get_user_check(x, ptr, size)					\
({                                                                      \
        long __gu_err = -EFAULT;                                        \
        unsigned long  __gu_val = 0;                                    \
        const __typeof__(*(ptr)) __user *__gu_addr = (ptr);             \
        might_fault();                                                  \
        if (access_ok(VERIFY_READ, __gu_addr, (size)))                  \
                __get_user_size(__gu_val, __gu_addr, (size), __gu_err); \
        (x) = (__force __typeof__(*(ptr)))__gu_val;                             \
        __gu_err;                                                       \
})


#define __get_user_nosleep(x, ptr, size)			\
({                                                              \
        long __gu_err;                                          \
        unsigned long __gu_val;                                 \
        const __typeof__(*(ptr)) __user *__gu_addr = (ptr);     \
        __chk_user_ptr(ptr);                                    \
        __get_user_size(__gu_val, __gu_addr, (size), __gu_err); \
        (x) = (__force __typeof__(*(ptr)))__gu_val;                     \
        __gu_err;                                               \
})


/* more complex routines */

extern unsigned long __copy_tofrom_user(void __user *to,
		const void __user *from, unsigned long size);

#ifdef __powerpc64__

static inline unsigned long raw_copy_in_user(void __user *to, const void __user *from, unsigned long n) { return __copy_tofrom_user(to, from, n); }

Contributors

PersonTokensPropCommitsCommitProp
Stephen Rothwell2987.88%125.00%
Al Viro26.06%125.00%
Kees Cook13.03%125.00%
Adrian Bunk13.03%125.00%
Total33100.00%4100.00%

#endif /* __powerpc64__ */
static inline unsigned long raw_copy_from_user(void *to, const void __user *from, unsigned long n) { if (__builtin_constant_p(n) && (n <= 8)) { unsigned long ret = 1; switch (n) { case 1: __get_user_size(*(u8 *)to, from, 1, ret); break; case 2: __get_user_size(*(u16 *)to, from, 2, ret); break; case 4: __get_user_size(*(u32 *)to, from, 4, ret); break; case 8: __get_user_size(*(u64 *)to, from, 8, ret); break; } if (ret == 0) return 0; } return __copy_tofrom_user((__force void __user *)to, from, n); }

Contributors

PersonTokensPropCommitsCommitProp
Anton Blanchard12581.17%225.00%
Stephen Rothwell2012.99%225.00%
Linus Torvalds53.25%112.50%
Al Viro21.30%225.00%
Nate Case21.30%112.50%
Total154100.00%8100.00%


static inline unsigned long raw_copy_to_user(void __user *to, const void *from, unsigned long n) { if (__builtin_constant_p(n) && (n <= 8)) { unsigned long ret = 1; switch (n) { case 1: __put_user_size(*(u8 *)from, (u8 __user *)to, 1, ret); break; case 2: __put_user_size(*(u16 *)from, (u16 __user *)to, 2, ret); break; case 4: __put_user_size(*(u32 *)from, (u32 __user *)to, 4, ret); break; case 8: __put_user_size(*(u64 *)from, (u64 __user *)to, 8, ret); break; } if (ret == 0) return 0; } return __copy_tofrom_user(to, (__force const void __user *)from, n); }

Contributors

PersonTokensPropCommitsCommitProp
Anton Blanchard12672.00%330.00%
Stephen Rothwell1910.86%220.00%
Paul Mackerras169.14%110.00%
Linus Torvalds105.71%110.00%
Al Viro21.14%220.00%
Nate Case21.14%110.00%
Total175100.00%10100.00%

extern unsigned long __clear_user(void __user *addr, unsigned long size);
static inline unsigned long clear_user(void __user *addr, unsigned long size) { might_fault(); if (likely(access_ok(VERIFY_WRITE, addr, size))) return __clear_user(addr, size); return size; }

Contributors

PersonTokensPropCommitsCommitProp
Anton Blanchard3680.00%562.50%
Stephen Rothwell715.56%112.50%
Linus Torvalds12.22%112.50%
Michael S. Tsirkin12.22%112.50%
Total45100.00%8100.00%

extern long strncpy_from_user(char *dst, const char __user *src, long count); extern __must_check long strnlen_user(const char __user *str, long n); #endif /* _ARCH_POWERPC_UACCESS_H */

Overall Contributors

PersonTokensPropCommitsCommitProp
Anton Blanchard52359.36%620.69%
Stephen Rothwell23226.33%310.34%
Benjamin Herrenschmidt434.88%13.45%
Paul Mackerras293.29%310.34%
Linus Torvalds192.16%13.45%
Al Viro91.02%310.34%
Nicholas Piggin70.79%13.45%
Michael Ellerman50.57%26.90%
Nate Case40.45%13.45%
Daniel Axtens30.34%310.34%
Michael S. Tsirkin30.34%13.45%
Bharat Bhushan10.11%13.45%
Kees Cook10.11%13.45%
Adrian Bunk10.11%13.45%
Greg Kroah-Hartman10.11%13.45%
Total881100.00%29100.00%
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