| /* 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> |
| |
| #ifdef CONFIG_SET_FS |
| /* |
| * Force the uaccess routines to be wired up for actual userspace access, |
| * overriding any possible set_fs(KERNEL_DS) still lingering around. Undone |
| * using force_uaccess_end below. |
| */ |
| static inline mm_segment_t force_uaccess_begin(void) |
| { |
| mm_segment_t fs = get_fs(); |
| |
| set_fs(USER_DS); |
| return fs; |
| } |
| |
| static inline void force_uaccess_end(mm_segment_t oldfs) |
| { |
| set_fs(oldfs); |
| } |
| #else /* CONFIG_SET_FS */ |
| typedef struct { |
| /* empty dummy */ |
| } mm_segment_t; |
| |
| #ifndef TASK_SIZE_MAX |
| #define TASK_SIZE_MAX TASK_SIZE |
| #endif |
| |
| #define uaccess_kernel() (false) |
| #define user_addr_max() (TASK_SIZE_MAX) |
| |
| static inline mm_segment_t force_uaccess_begin(void) |
| { |
| return (mm_segment_t) { }; |
| } |
| |
| static inline void force_uaccess_end(mm_segment_t oldfs) |
| { |
| } |
| #endif /* CONFIG_SET_FS */ |
| |
| /* |
| * 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 (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; |
| } |
| |
| #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 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); |
| |
| /** |
| * 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 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__ */ |