302 lines
9.9 KiB
C
302 lines
9.9 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __LINUX_UACCESS_H__
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#define __LINUX_UACCESS_H__
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#include <linux/sched.h>
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#include <linux/thread_info.h>
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#include <linux/kasan-checks.h>
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#define uaccess_kernel() segment_eq(get_fs(), KERNEL_DS)
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#include <asm/uaccess.h>
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/*
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* Architectures should provide two primitives (raw_copy_{to,from}_user())
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* and get rid of their private instances of copy_{to,from}_user() and
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* __copy_{to,from}_user{,_inatomic}().
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*
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* raw_copy_{to,from}_user(to, from, size) should copy up to size bytes and
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* return the amount left to copy. They should assume that access_ok() has
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* already been checked (and succeeded); they should *not* zero-pad anything.
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* No KASAN or object size checks either - those belong here.
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*
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* Both of these functions should attempt to copy size bytes starting at from
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* into the area starting at to. They must not fetch or store anything
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* outside of those areas. Return value must be between 0 (everything
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* copied successfully) and size (nothing copied).
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*
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* If raw_copy_{to,from}_user(to, from, size) returns N, size - N bytes starting
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* at to must become equal to the bytes fetched from the corresponding area
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* starting at from. All data past to + size - N must be left unmodified.
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*
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* If copying succeeds, the return value must be 0. If some data cannot be
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* fetched, it is permitted to copy less than had been fetched; the only
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* hard requirement is that not storing anything at all (i.e. returning size)
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* should happen only when nothing could be copied. In other words, you don't
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* have to squeeze as much as possible - it is allowed, but not necessary.
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*
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* For raw_copy_from_user() to always points to kernel memory and no faults
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* on store should happen. Interpretation of from is affected by set_fs().
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* For raw_copy_to_user() it's the other way round.
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*
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* Both can be inlined - it's up to architectures whether it wants to bother
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* with that. They should not be used directly; they are used to implement
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* the 6 functions (copy_{to,from}_user(), __copy_{to,from}_user_inatomic())
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* that are used instead. Out of those, __... ones are inlined. Plain
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* copy_{to,from}_user() might or might not be inlined. If you want them
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* inlined, have asm/uaccess.h define INLINE_COPY_{TO,FROM}_USER.
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*
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* NOTE: only copy_from_user() zero-pads the destination in case of short copy.
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* Neither __copy_from_user() nor __copy_from_user_inatomic() zero anything
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* at all; their callers absolutely must check the return value.
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*
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* Biarch ones should also provide raw_copy_in_user() - similar to the above,
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* but both source and destination are __user pointers (affected by set_fs()
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* as usual) and both source and destination can trigger faults.
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*/
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static __always_inline unsigned long
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__copy_from_user_inatomic(void *to, const void __user *from, unsigned long n)
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{
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kasan_check_write(to, n);
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check_object_size(to, n, false);
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return raw_copy_from_user(to, from, n);
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}
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static __always_inline unsigned long
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__copy_from_user(void *to, const void __user *from, unsigned long n)
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{
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might_fault();
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kasan_check_write(to, n);
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check_object_size(to, n, false);
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return raw_copy_from_user(to, from, n);
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}
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/**
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* __copy_to_user_inatomic: - Copy a block of data into user space, with less checking.
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* @to: Destination address, in user space.
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* @from: Source address, in kernel space.
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* @n: Number of bytes to copy.
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*
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* Context: User context only.
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*
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* Copy data from kernel space to user space. Caller must check
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* the specified block with access_ok() before calling this function.
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* The caller should also make sure he pins the user space address
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* so that we don't result in page fault and sleep.
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*/
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static __always_inline unsigned long
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__copy_to_user_inatomic(void __user *to, const void *from, unsigned long n)
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{
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kasan_check_read(from, n);
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check_object_size(from, n, true);
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return raw_copy_to_user(to, from, n);
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}
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static __always_inline unsigned long
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__copy_to_user(void __user *to, const void *from, unsigned long n)
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{
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might_fault();
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kasan_check_read(from, n);
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check_object_size(from, n, true);
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return raw_copy_to_user(to, from, n);
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}
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#ifdef INLINE_COPY_FROM_USER
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static inline unsigned long
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_copy_from_user(void *to, const void __user *from, unsigned long n)
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{
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unsigned long res = n;
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might_fault();
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if (likely(access_ok(from, n))) {
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kasan_check_write(to, n);
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res = raw_copy_from_user(to, from, n);
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}
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if (unlikely(res))
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memset(to + (n - res), 0, res);
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return res;
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}
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#else
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extern unsigned long
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_copy_from_user(void *, const void __user *, unsigned long);
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#endif
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#ifdef INLINE_COPY_TO_USER
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static inline unsigned long
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_copy_to_user(void __user *to, const void *from, unsigned long n)
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{
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might_fault();
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if (access_ok(to, n)) {
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kasan_check_read(from, n);
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n = raw_copy_to_user(to, from, n);
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}
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return n;
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}
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#else
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extern unsigned long
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_copy_to_user(void __user *, const void *, unsigned long);
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#endif
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static __always_inline unsigned long __must_check
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copy_from_user(void *to, const void __user *from, unsigned long n)
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{
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if (likely(check_copy_size(to, n, false)))
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n = _copy_from_user(to, from, n);
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return n;
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}
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static __always_inline unsigned long __must_check
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copy_to_user(void __user *to, const void *from, unsigned long n)
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{
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if (likely(check_copy_size(from, n, true)))
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n = _copy_to_user(to, from, n);
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return n;
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}
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#ifdef CONFIG_COMPAT
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static __always_inline unsigned long __must_check
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copy_in_user(void __user *to, const void __user *from, unsigned long n)
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{
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might_fault();
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if (access_ok(to, n) && access_ok(from, n))
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n = raw_copy_in_user(to, from, n);
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return n;
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}
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#endif
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static __always_inline void pagefault_disabled_inc(void)
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{
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current->pagefault_disabled++;
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}
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static __always_inline void pagefault_disabled_dec(void)
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{
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current->pagefault_disabled--;
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}
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/*
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* These routines enable/disable the pagefault handler. If disabled, it will
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* not take any locks and go straight to the fixup table.
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*
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* User access methods will not sleep when called from a pagefault_disabled()
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* environment.
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*/
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static inline void pagefault_disable(void)
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{
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pagefault_disabled_inc();
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/*
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* make sure to have issued the store before a pagefault
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* can hit.
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*/
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barrier();
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}
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static inline void pagefault_enable(void)
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{
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/*
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* make sure to issue those last loads/stores before enabling
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* the pagefault handler again.
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*/
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barrier();
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pagefault_disabled_dec();
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}
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/*
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* Is the pagefault handler disabled? If so, user access methods will not sleep.
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*/
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static inline bool pagefault_disabled(void)
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{
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return current->pagefault_disabled != 0;
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}
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/*
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* The pagefault handler is in general disabled by pagefault_disable() or
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* when in irq context (via in_atomic()).
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*
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* This function should only be used by the fault handlers. Other users should
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* stick to pagefault_disabled().
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* Please NEVER use preempt_disable() to disable the fault handler. With
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* !CONFIG_PREEMPT_COUNT, this is like a NOP. So the handler won't be disabled.
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* in_atomic() will report different values based on !CONFIG_PREEMPT_COUNT.
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*/
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#define faulthandler_disabled() (pagefault_disabled() || in_atomic())
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#ifndef ARCH_HAS_NOCACHE_UACCESS
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static inline unsigned long __copy_from_user_inatomic_nocache(void *to,
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const void __user *from, unsigned long n)
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{
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return __copy_from_user_inatomic(to, from, n);
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}
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#endif /* ARCH_HAS_NOCACHE_UACCESS */
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/*
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* probe_kernel_read(): safely attempt to read from a location
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* @dst: pointer to the buffer that shall take the data
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* @src: address to read from
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* @size: size of the data chunk
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*
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* Safely read from address @src to the buffer at @dst. If a kernel fault
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* happens, handle that and return -EFAULT.
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*/
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extern long probe_kernel_read(void *dst, const void *src, size_t size);
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extern long __probe_kernel_read(void *dst, const void *src, size_t size);
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/*
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* probe_user_read(): safely attempt to read from a location in user space
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* @dst: pointer to the buffer that shall take the data
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* @src: address to read from
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* @size: size of the data chunk
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*
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* Safely read from address @src to the buffer at @dst. If a kernel fault
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* happens, handle that and return -EFAULT.
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*/
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extern long probe_user_read(void *dst, const void __user *src, size_t size);
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extern long __probe_user_read(void *dst, const void __user *src, size_t size);
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/*
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* probe_kernel_write(): safely attempt to write to a location
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* @dst: address to write to
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* @src: pointer to the data that shall be written
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* @size: size of the data chunk
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*
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* Safely write to address @dst from the buffer at @src. If a kernel fault
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* happens, handle that and return -EFAULT.
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*/
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extern long notrace probe_kernel_write(void *dst, const void *src, size_t size);
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extern long notrace __probe_kernel_write(void *dst, const void *src, size_t size);
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extern long strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count);
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extern long strncpy_from_unsafe_user(char *dst, const void __user *unsafe_addr,
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long count);
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extern long strnlen_unsafe_user(const void __user *unsafe_addr, long count);
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/**
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* probe_kernel_address(): safely attempt to read from a location
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* @addr: address to read from
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* @retval: read into this variable
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*
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* Returns 0 on success, or -EFAULT.
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*/
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#define probe_kernel_address(addr, retval) \
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probe_kernel_read(&retval, addr, sizeof(retval))
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#ifndef user_access_begin
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#define user_access_begin(ptr,len) access_ok(ptr, len)
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#define user_access_end() do { } while (0)
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#define unsafe_get_user(x, ptr, err) do { if (unlikely(__get_user(x, ptr))) goto err; } while (0)
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#define unsafe_put_user(x, ptr, err) do { if (unlikely(__put_user(x, ptr))) goto err; } while (0)
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static inline unsigned long user_access_save(void) { return 0UL; }
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static inline void user_access_restore(unsigned long flags) { }
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#endif
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#ifdef CONFIG_HARDENED_USERCOPY
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void usercopy_warn(const char *name, const char *detail, bool to_user,
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unsigned long offset, unsigned long len);
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void __noreturn usercopy_abort(const char *name, const char *detail,
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bool to_user, unsigned long offset,
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unsigned long len);
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#endif
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#endif /* __LINUX_UACCESS_H__ */
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