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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)
- {
- unsigned long res;
- instrument_copy_from_user_before(to, from, n);
- check_object_size(to, n, false);
- res = raw_copy_from_user(to, from, n);
- instrument_copy_from_user_after(to, from, n, res);
- return res;
- }
- static __always_inline __must_check unsigned long
- __copy_from_user(void *to, const void __user *from, unsigned long n)
- {
- unsigned long res;
- might_fault();
- instrument_copy_from_user_before(to, from, n);
- if (should_fail_usercopy())
- return n;
- check_object_size(to, n, false);
- res = raw_copy_from_user(to, from, n);
- instrument_copy_from_user_after(to, from, n, res);
- return res;
- }
- /**
- * __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_before(to, from, n);
- res = raw_copy_from_user(to, from, n);
- instrument_copy_from_user_after(to, from, n, res);
- }
- 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;
- /* Double check if ksize is larger than a known object size. */
- if (WARN_ON_ONCE(ksize > __builtin_object_size(dst, 1)))
- return -E2BIG;
- /* 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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