forked from mirrors/linux
1f9a8286bc
Rust code needs to be able to access _copy_from_user and _copy_to_user so that it can skip the check_copy_size check in cases where the length is known at compile-time, mirroring the logic for when C code will skip check_copy_size. To do this, we ensure that exported versions of these methods are available when CONFIG_RUST is enabled. Alice has verified that this patch passes the CONFIG_TEST_USER_COPY test on x86 using the Android cuttlefish emulator. Signed-off-by: Arnd Bergmann <arnd@arndb.de> Tested-by: Alice Ryhl <aliceryhl@google.com> Reviewed-by: Boqun Feng <boqun.feng@gmail.com> Reviewed-by: Kees Cook <keescook@chromium.org> Signed-off-by: Alice Ryhl <aliceryhl@google.com> Acked-by: Andrew Morton <akpm@linux-foundation.org> Link: https://lore.kernel.org/r/20240528-alice-mm-v7-2-78222c31b8f4@google.com Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
83 lines
2.1 KiB
C
83 lines
2.1 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#include <linux/compiler.h>
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#include <linux/errno.h>
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#include <linux/export.h>
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#include <linux/fault-inject-usercopy.h>
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#include <linux/instrumented.h>
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#include <linux/kernel.h>
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#include <linux/nospec.h>
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#include <linux/string.h>
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#include <linux/uaccess.h>
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#include <linux/wordpart.h>
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/* out-of-line parts */
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#if !defined(INLINE_COPY_FROM_USER) || defined(CONFIG_RUST)
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unsigned long _copy_from_user(void *to, const void __user *from, unsigned long n)
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{
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return _inline_copy_from_user(to, from, n);
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}
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EXPORT_SYMBOL(_copy_from_user);
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#endif
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#if !defined(INLINE_COPY_TO_USER) || defined(CONFIG_RUST)
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unsigned long _copy_to_user(void __user *to, const void *from, unsigned long n)
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{
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return _inline_copy_to_user(to, from, n);
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}
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EXPORT_SYMBOL(_copy_to_user);
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#endif
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/**
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* check_zeroed_user: check if a userspace buffer only contains zero bytes
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* @from: Source address, in userspace.
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* @size: Size of buffer.
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*
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* This is effectively shorthand for "memchr_inv(from, 0, size) == NULL" for
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* userspace addresses (and is more efficient because we don't care where the
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* first non-zero byte is).
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*
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* Returns:
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* * 0: There were non-zero bytes present in the buffer.
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* * 1: The buffer was full of zero bytes.
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* * -EFAULT: access to userspace failed.
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*/
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int check_zeroed_user(const void __user *from, size_t size)
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{
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unsigned long val;
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uintptr_t align = (uintptr_t) from % sizeof(unsigned long);
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if (unlikely(size == 0))
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return 1;
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from -= align;
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size += align;
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if (!user_read_access_begin(from, size))
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return -EFAULT;
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unsafe_get_user(val, (unsigned long __user *) from, err_fault);
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if (align)
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val &= ~aligned_byte_mask(align);
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while (size > sizeof(unsigned long)) {
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if (unlikely(val))
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goto done;
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from += sizeof(unsigned long);
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size -= sizeof(unsigned long);
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unsafe_get_user(val, (unsigned long __user *) from, err_fault);
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}
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if (size < sizeof(unsigned long))
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val &= aligned_byte_mask(size);
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done:
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user_read_access_end();
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return (val == 0);
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err_fault:
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user_read_access_end();
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return -EFAULT;
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}
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EXPORT_SYMBOL(check_zeroed_user);
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