282 lines
9.1 KiB
C
282 lines
9.1 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
|
|
#ifndef __LINUX_UACCESS_H__
|
|
#define __LINUX_UACCESS_H__
|
|
|
|
#include <linux/sched.h>
|
|
#include <linux/thread_info.h>
|
|
#include <linux/kasan-checks.h>
|
|
|
|
#define uaccess_kernel() segment_eq(get_fs(), KERNEL_DS)
|
|
|
|
#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 unsigned long
|
|
__copy_from_user_inatomic(void *to, const void __user *from, unsigned long n)
|
|
{
|
|
kasan_check_write(to, n);
|
|
check_object_size(to, n, false);
|
|
return raw_copy_from_user(to, from, n);
|
|
}
|
|
|
|
static __always_inline unsigned long
|
|
__copy_from_user(void *to, const void __user *from, unsigned long n)
|
|
{
|
|
might_fault();
|
|
kasan_check_write(to, 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 unsigned long
|
|
__copy_to_user_inatomic(void __user *to, const void *from, unsigned long n)
|
|
{
|
|
kasan_check_read(from, n);
|
|
check_object_size(from, n, true);
|
|
return raw_copy_to_user(to, from, n);
|
|
}
|
|
|
|
static __always_inline unsigned long
|
|
__copy_to_user(void __user *to, const void *from, unsigned long n)
|
|
{
|
|
might_fault();
|
|
kasan_check_read(from, n);
|
|
check_object_size(from, n, true);
|
|
return raw_copy_to_user(to, from, n);
|
|
}
|
|
|
|
#ifdef INLINE_COPY_FROM_USER
|
|
static inline unsigned long
|
|
_copy_from_user(void *to, const void __user *from, unsigned long n)
|
|
{
|
|
unsigned long res = n;
|
|
might_fault();
|
|
if (likely(access_ok(from, n))) {
|
|
kasan_check_write(to, n);
|
|
res = raw_copy_from_user(to, from, n);
|
|
}
|
|
if (unlikely(res))
|
|
memset(to + (n - res), 0, res);
|
|
return res;
|
|
}
|
|
#else
|
|
extern unsigned long
|
|
_copy_from_user(void *, const void __user *, unsigned long);
|
|
#endif
|
|
|
|
#ifdef INLINE_COPY_TO_USER
|
|
static inline unsigned long
|
|
_copy_to_user(void __user *to, const void *from, unsigned long n)
|
|
{
|
|
might_fault();
|
|
if (access_ok(to, n)) {
|
|
kasan_check_read(from, n);
|
|
n = raw_copy_to_user(to, from, n);
|
|
}
|
|
return n;
|
|
}
|
|
#else
|
|
extern 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 (likely(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 (likely(check_copy_size(from, n, true)))
|
|
n = _copy_to_user(to, from, n);
|
|
return n;
|
|
}
|
|
#ifdef CONFIG_COMPAT
|
|
static __always_inline unsigned long __must_check
|
|
copy_in_user(void __user *to, const void __user *from, unsigned long n)
|
|
{
|
|
might_fault();
|
|
if (access_ok(to, n) && access_ok(from, n))
|
|
n = raw_copy_in_user(to, from, n);
|
|
return n;
|
|
}
|
|
#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.
|
|
*/
|
|
#define pagefault_disabled() (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 ARCH_HAS_NOCACHE_UACCESS
|
|
|
|
static inline 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 */
|
|
|
|
/*
|
|
* probe_kernel_read(): safely attempt to read from a location
|
|
* @dst: pointer to the buffer that shall take the data
|
|
* @src: address to read from
|
|
* @size: size of the data chunk
|
|
*
|
|
* Safely read from address @src to the buffer at @dst. If a kernel fault
|
|
* happens, handle that and return -EFAULT.
|
|
*/
|
|
extern long probe_kernel_read(void *dst, const void *src, size_t size);
|
|
extern long __probe_kernel_read(void *dst, const void *src, size_t size);
|
|
|
|
/*
|
|
* probe_kernel_write(): safely attempt to write to a location
|
|
* @dst: address to write to
|
|
* @src: pointer to the data that shall be written
|
|
* @size: size of the data chunk
|
|
*
|
|
* Safely write to address @dst from the buffer at @src. If a kernel fault
|
|
* happens, handle that and return -EFAULT.
|
|
*/
|
|
extern long notrace probe_kernel_write(void *dst, const void *src, size_t size);
|
|
extern long notrace __probe_kernel_write(void *dst, const void *src, size_t size);
|
|
|
|
extern long strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count);
|
|
|
|
/**
|
|
* probe_kernel_address(): safely attempt to read from a location
|
|
* @addr: address to read from
|
|
* @retval: read into this variable
|
|
*
|
|
* Returns 0 on success, or -EFAULT.
|
|
*/
|
|
#define probe_kernel_address(addr, retval) \
|
|
probe_kernel_read(&retval, addr, sizeof(retval))
|
|
|
|
#ifndef user_access_begin
|
|
#define user_access_begin(ptr,len) access_ok(ptr, len)
|
|
#define user_access_end() do { } while (0)
|
|
#define unsafe_get_user(x, ptr, err) do { if (unlikely(__get_user(x, ptr))) goto err; } while (0)
|
|
#define unsafe_put_user(x, ptr, err) do { if (unlikely(__put_user(x, ptr))) goto err; } while (0)
|
|
#endif
|
|
|
|
#ifdef CONFIG_HARDENED_USERCOPY
|
|
void usercopy_warn(const char *name, const char *detail, bool to_user,
|
|
unsigned long offset, unsigned long len);
|
|
void __noreturn usercopy_abort(const char *name, const char *detail,
|
|
bool to_user, unsigned long offset,
|
|
unsigned long len);
|
|
#endif
|
|
|
|
#endif /* __LINUX_UACCESS_H__ */
|