424 строки
14 KiB
C
424 строки
14 KiB
C
/* 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__ */
|