forked from mirrors/linux
496d2d2388
HARDENED_USERCOPY is checked within a function so even if disabled, the function overhead still exists. Move the static check inline. This is at best a micro-optimisation and any difference in performance was within noise but it is relatively consistent with the init_on_* implementations. Suggested-by: Kees Cook <kees@kernel.org> Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Link: https://lore.kernel.org/r/20250123221115.19722-4-mgorman@techsingularity.net Signed-off-by: Kees Cook <kees@kernel.org>
63 lines
1.7 KiB
C
63 lines
1.7 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/* Perform sanity checking for object sizes for uaccess.h and uio.h. */
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#ifndef __LINUX_UCOPYSIZE_H__
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#define __LINUX_UCOPYSIZE_H__
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#include <linux/bug.h>
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#ifdef CONFIG_HARDENED_USERCOPY
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#include <linux/jump_label.h>
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extern void __check_object_size(const void *ptr, unsigned long n,
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bool to_user);
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DECLARE_STATIC_KEY_MAYBE(CONFIG_HARDENED_USERCOPY_DEFAULT_ON,
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validate_usercopy_range);
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static __always_inline void check_object_size(const void *ptr, unsigned long n,
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bool to_user)
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{
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if (!__builtin_constant_p(n) &&
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static_branch_maybe(CONFIG_HARDENED_USERCOPY_DEFAULT_ON,
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&validate_usercopy_range)) {
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__check_object_size(ptr, n, to_user);
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}
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}
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#else
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static inline void check_object_size(const void *ptr, unsigned long n,
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bool to_user)
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{ }
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#endif /* CONFIG_HARDENED_USERCOPY */
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extern void __compiletime_error("copy source size is too small")
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__bad_copy_from(void);
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extern void __compiletime_error("copy destination size is too small")
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__bad_copy_to(void);
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void __copy_overflow(int size, unsigned long count);
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static inline void copy_overflow(int size, unsigned long count)
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{
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if (IS_ENABLED(CONFIG_BUG))
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__copy_overflow(size, count);
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}
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static __always_inline __must_check bool
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check_copy_size(const void *addr, size_t bytes, bool is_source)
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{
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int sz = __builtin_object_size(addr, 0);
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if (unlikely(sz >= 0 && sz < bytes)) {
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if (!__builtin_constant_p(bytes))
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copy_overflow(sz, bytes);
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else if (is_source)
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__bad_copy_from();
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else
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__bad_copy_to();
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return false;
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}
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if (WARN_ON_ONCE(bytes > INT_MAX))
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return false;
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check_object_size(addr, bytes, is_source);
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return true;
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}
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#endif /* __LINUX_UCOPYSIZE_H__ */
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