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 /* SPDX-License-Identifier: GPL-2.0 */
 #ifndef __LINUX_UACCESS_H__
 #define __LINUX_UACCESS_H__
 
 #include <linux/fault-inject-usercopy.h>
 #include <linux/instrumented.h>
 #include <linux/minmax.h>
 #include <linux/sched.h>
 #include <linux/thread_info.h>
 
 #include <asm/uaccess.h>
 
 /*
  * Architectures should provide two primitives (raw_copy_{to,from}_user())
  * and get rid of their private instances of copy_{to,from}_user() and
  * __copy_{to,from}_user{,_inatomic}().
  *
  * raw_copy_{to,from}_user(to, from, size) should copy up to size bytes and
  * return the amount left to copy.  They should assume that access_ok() has
  * already been checked (and succeeded); they should *not* zero-pad anything.
  * No KASAN or object size checks either - those belong here.
  *
  * Both of these functions should attempt to copy size bytes starting at from
  * into the area starting at to.  They must not fetch or store anything
  * outside of those areas.  Return value must be between 0 (everything
  * copied successfully) and size (nothing copied).
  *
  * If raw_copy_{to,from}_user(to, from, size) returns N, size - N bytes starting
  * at to must become equal to the bytes fetched from the corresponding area
  * starting at from.  All data past to + size - N must be left unmodified.
  *
  * If copying succeeds, the return value must be 0.  If some data cannot be
  * fetched, it is permitted to copy less than had been fetched; the only
  * hard requirement is that not storing anything at all (i.e. returning size)
  * should happen only when nothing could be copied.  In other words, you don't
  * have to squeeze as much as possible - it is allowed, but not necessary.
  *
  * For raw_copy_from_user() to always points to kernel memory and no faults
  * on store should happen.  Interpretation of from is affected by set_fs().
  * For raw_copy_to_user() it's the other way round.
  *
  * Both can be inlined - it's up to architectures whether it wants to bother
  * with that.  They should not be used directly; they are used to implement
  * the 6 functions (copy_{to,from}_user(), __copy_{to,from}_user_inatomic())
  * that are used instead.  Out of those, __... ones are inlined.  Plain
  * copy_{to,from}_user() might or might not be inlined.  If you want them
  * inlined, have asm/uaccess.h define INLINE_COPY_{TO,FROM}_USER.
  *
  * NOTE: only copy_from_user() zero-pads the destination in case of short copy.
  * Neither __copy_from_user() nor __copy_from_user_inatomic() zero anything
  * at all; their callers absolutely must check the return value.
  *
  * Biarch ones should also provide raw_copy_in_user() - similar to the above,
  * but both source and destination are __user pointers (affected by set_fs()
  * as usual) and both source and destination can trigger faults.
  */
 
 static __always_inline __must_check unsigned long
 __copy_from_user_inatomic(void *to, const void __user *from, unsigned long n)
 {
     instrument_copy_from_user(to, from, n);
     check_object_size(to, n, false);
     return raw_copy_from_user(to, from, n);
 }
 
 static __always_inline __must_check unsigned long
 __copy_from_user(void *to, const void __user *from, unsigned long n)
 {
     might_fault();
     if (should_fail_usercopy())
         return n;
     instrument_copy_from_user(to, from, n);
     check_object_size(to, n, false);
     return raw_copy_from_user(to, from, n);
 }
 
 /**
  * __copy_to_user_inatomic: - Copy a block of data into user space, with less checking.
  * @to:   Destination address, in user space.
  * @from: Source address, in kernel space.
  * @n:    Number of bytes to copy.
  *
  * Context: User context only.
  *
  * Copy data from kernel space to user space.  Caller must check
  * the specified block with access_ok() before calling this function.
  * The caller should also make sure he pins the user space address
  * so that we don't result in page fault and sleep.
  */
 static __always_inline __must_check unsigned long
 __copy_to_user_inatomic(void __user *to, const void *from, unsigned long n)
 {
     if (should_fail_usercopy())
         return n;
     instrument_copy_to_user(to, from, n);
     check_object_size(from, n, true);
     return raw_copy_to_user(to, from, n);
 }
 
 static __always_inline __must_check unsigned long
 __copy_to_user(void __user *to, const void *from, unsigned long n)
 {
     might_fault();
     if (should_fail_usercopy())
         return n;
     instrument_copy_to_user(to, from, n);
     check_object_size(from, n, true);
     return raw_copy_to_user(to, from, n);
 }
 
 #ifdef INLINE_COPY_FROM_USER
 static inline __must_check unsigned long
 _copy_from_user(void *to, const void __user *from, unsigned long n)
 {
     unsigned long res = n;
     might_fault();
     if (!should_fail_usercopy() && likely(access_ok(from, n))) {
         instrument_copy_from_user(to, from, n);
         res = raw_copy_from_user(to, from, n);
     }
     if (unlikely(res))
         memset(to + (n - res), 0, res);
     return res;
 }
 #else
 extern __must_check unsigned long
 _copy_from_user(void *, const void __user *, unsigned long);
 #endif
 
 #ifdef INLINE_COPY_TO_USER
 static inline __must_check unsigned long
 _copy_to_user(void __user *to, const void *from, unsigned long n)
 {
     might_fault();
     if (should_fail_usercopy())
         return n;
     if (access_ok(to, n)) {
         instrument_copy_to_user(to, from, n);
         n = raw_copy_to_user(to, from, n);
     }
     return n;
 }
 #else
 extern __must_check unsigned long
 _copy_to_user(void __user *, const void *, unsigned long);
 #endif
 
 static __always_inline unsigned long __must_check
 copy_from_user(void *to, const void __user *from, unsigned long n)
 {
     if (check_copy_size(to, n, false))
         n = _copy_from_user(to, from, n);
     return n;
 }
 
 static __always_inline unsigned long __must_check
 copy_to_user(void __user *to, const void *from, unsigned long n)
 {
     if (check_copy_size(from, n, true))
         n = _copy_to_user(to, from, n);
     return n;
 }
 
 #ifndef copy_mc_to_kernel
 /*
  * Without arch opt-in this generic copy_mc_to_kernel() will not handle
  * #MC (or arch equivalent) during source read.
  */
 static inline unsigned long __must_check
 copy_mc_to_kernel(void *dst, const void *src, size_t cnt)
 {
     memcpy(dst, src, cnt);
     return 0;
 }
 #endif
 
 static __always_inline void pagefault_disabled_inc(void)
 {
     current->pagefault_disabled++;
 }
 
 static __always_inline void pagefault_disabled_dec(void)
 {
     current->pagefault_disabled--;
 }
 
 /*
  * These routines enable/disable the pagefault handler. If disabled, it will
  * not take any locks and go straight to the fixup table.
  *
  * User access methods will not sleep when called from a pagefault_disabled()
  * environment.
  */
 static inline void pagefault_disable(void)
 {
     pagefault_disabled_inc();
     /*
      * make sure to have issued the store before a pagefault
      * can hit.
      */
     barrier();
 }
 
 static inline void pagefault_enable(void)
 {
     /*
      * make sure to issue those last loads/stores before enabling
      * the pagefault handler again.
      */
     barrier();
     pagefault_disabled_dec();
 }
 
 /*
  * Is the pagefault handler disabled? If so, user access methods will not sleep.
  */
 static inline bool pagefault_disabled(void)
 {
     return current->pagefault_disabled != 0;
 }
 
 /*
  * The pagefault handler is in general disabled by pagefault_disable() or
  * when in irq context (via in_atomic()).
  *
  * This function should only be used by the fault handlers. Other users should
  * stick to pagefault_disabled().
  * Please NEVER use preempt_disable() to disable the fault handler. With
  * !CONFIG_PREEMPT_COUNT, this is like a NOP. So the handler won't be disabled.
  * in_atomic() will report different values based on !CONFIG_PREEMPT_COUNT.
  */
 #define faulthandler_disabled() (pagefault_disabled() || in_atomic())
 
 #ifndef CONFIG_ARCH_HAS_SUBPAGE_FAULTS
 
 /**
  * probe_subpage_writeable: probe the user range for write faults at sub-page
  *              granularity (e.g. arm64 MTE)
  * @uaddr: start of address range
  * @size: size of address range
  *
  * Returns 0 on success, the number of bytes not probed on fault.
  *
  * It is expected that the caller checked for the write permission of each
  * page in the range either by put_user() or GUP. The architecture port can
  * implement a more efficient get_user() probing if the same sub-page faults
  * are triggered by either a read or a write.
  */
 static inline size_t probe_subpage_writeable(char __user *uaddr, size_t size)
 {
     return 0;
 }
 
 #endif /* CONFIG_ARCH_HAS_SUBPAGE_FAULTS */
 
 #ifndef ARCH_HAS_NOCACHE_UACCESS
 
 static inline __must_check unsigned long
 __copy_from_user_inatomic_nocache(void *to, const void __user *from,
                   unsigned long n)
 {
     return __copy_from_user_inatomic(to, from, n);
 }
 
 #endif      /* ARCH_HAS_NOCACHE_UACCESS */
 
 extern __must_check int check_zeroed_user(const void __user *from, size_t size);
 
 /**
  * copy_struct_from_user: copy a struct from userspace
  * @dst:   Destination address, in kernel space. This buffer must be @ksize
  *         bytes long.
  * @ksize: Size of @dst struct.
  * @src:   Source address, in userspace.
  * @usize: (Alleged) size of @src struct.
  *
  * Copies a struct from userspace to kernel space, in a way that guarantees
  * backwards-compatibility for struct syscall arguments (as long as future
  * struct extensions are made such that all new fields are *appended* to the
  * old struct, and zeroed-out new fields have the same meaning as the old
  * struct).
  *
  * @ksize is just sizeof(*dst), and @usize should've been passed by userspace.
  * The recommended usage is something like the following:
  *
  *   SYSCALL_DEFINE2(foobar, const struct foo __user *, uarg, size_t, usize)
  *   {
  *      int err;
  *      struct foo karg = {};
  *
  *      if (usize > PAGE_SIZE)
  *        return -E2BIG;
  *      if (usize < FOO_SIZE_VER0)
  *        return -EINVAL;
  *
  *      err = copy_struct_from_user(&karg, sizeof(karg), uarg, usize);
  *      if (err)
  *        return err;
  *
  *      // ...
  *   }
  *
  * There are three cases to consider:
  *  * If @usize == @ksize, then it's copied verbatim.
  *  * If @usize < @ksize, then the userspace has passed an old struct to a
  *    newer kernel. The rest of the trailing bytes in @dst (@ksize - @usize)
  *    are to be zero-filled.
  *  * If @usize > @ksize, then the userspace has passed a new struct to an
  *    older kernel. The trailing bytes unknown to the kernel (@usize - @ksize)
  *    are checked to ensure they are zeroed, otherwise -E2BIG is returned.
  *
  * Returns (in all cases, some data may have been copied):
  *  * -E2BIG:  (@usize > @ksize) and there are non-zero trailing bytes in @src.
  *  * -EFAULT: access to userspace failed.
  */
 static __always_inline __must_check int
 copy_struct_from_user(void *dst, size_t ksize, const void __user *src,
               size_t usize)
 {
     size_t size = min(ksize, usize);
     size_t rest = max(ksize, usize) - size;
 
     /* Deal with trailing bytes. */
     if (usize < ksize) {
         memset(dst + size, 0, rest);
     } else if (usize > ksize) {
         int ret = check_zeroed_user(src + size, rest);
         if (ret <= 0)
             return ret ?: -E2BIG;
     }
     /* Copy the interoperable parts of the struct. */
     if (copy_from_user(dst, src, size))
         return -EFAULT;
     return 0;
 }
 
 bool copy_from_kernel_nofault_allowed(const void *unsafe_src, size_t size);
 
 long copy_from_kernel_nofault(void *dst, const void *src, size_t size);
 long notrace copy_to_kernel_nofault(void *dst, const void *src, size_t size);
 
 long copy_from_user_nofault(void *dst, const void __user *src, size_t size);
 long notrace copy_to_user_nofault(void __user *dst, const void *src,
         size_t size);
 
 long strncpy_from_kernel_nofault(char *dst, const void *unsafe_addr,
         long count);
 
 long strncpy_from_user_nofault(char *dst, const void __user *unsafe_addr,
         long count);
 long strnlen_user_nofault(const void __user *unsafe_addr, long count);
 
 #ifndef __get_kernel_nofault
 #define __get_kernel_nofault(dst, src, type, label) \
 do {                            \
     type __user *p = (type __force __user *)(src);  \
     type data;                  \
     if (__get_user(data, p))            \
         goto label;             \
     *(type *)dst = data;                \
 } while (0)
 
 #define __put_kernel_nofault(dst, src, type, label) \
 do {                            \
     type __user *p = (type __force __user *)(dst);  \
     type data = *(type *)src;           \
     if (__put_user(data, p))            \
         goto label;             \
 } while (0)
 #endif
 
 /**
  * get_kernel_nofault(): safely attempt to read from a location
  * @val: read into this variable
  * @ptr: address to read from
  *
  * Returns 0 on success, or -EFAULT.
  */
 #define get_kernel_nofault(val, ptr) ({             \
     const typeof(val) *__gk_ptr = (ptr);            \
     copy_from_kernel_nofault(&(val), __gk_ptr, sizeof(val));\
 })
 
 #ifndef user_access_begin
 #define user_access_begin(ptr,len) access_ok(ptr, len)
 #define user_access_end() do { } while (0)
 #define unsafe_op_wrap(op, err) do { if (unlikely(op)) goto err; } while (0)
 #define unsafe_get_user(x,p,e) unsafe_op_wrap(__get_user(x,p),e)
 #define unsafe_put_user(x,p,e) unsafe_op_wrap(__put_user(x,p),e)
 #define unsafe_copy_to_user(d,s,l,e) unsafe_op_wrap(__copy_to_user(d,s,l),e)
 #define unsafe_copy_from_user(d,s,l,e) unsafe_op_wrap(__copy_from_user(d,s,l),e)
 static inline unsigned long user_access_save(void) { return 0UL; }
 static inline void user_access_restore(unsigned long flags) { }
 #endif
 #ifndef user_write_access_begin
 #define user_write_access_begin user_access_begin
 #define user_write_access_end user_access_end
 #endif
 #ifndef user_read_access_begin
 #define user_read_access_begin user_access_begin
 #define user_read_access_end user_access_end
 #endif
 
 #ifdef CONFIG_HARDENED_USERCOPY
 void __noreturn usercopy_abort(const char *name, const char *detail,
                    bool to_user, unsigned long offset,
                    unsigned long len);
 #endif
 
 #endif      /* __LINUX_UACCESS_H__ */

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