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uaccess: always export _copy_[from|to]_user with CONFIG_RUST
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>
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@ -5,6 +5,7 @@
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#include <linux/fault-inject-usercopy.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/instrumented.h>
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#include <linux/minmax.h>
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#include <linux/minmax.h>
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#include <linux/nospec.h>
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#include <linux/sched.h>
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#include <linux/sched.h>
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#include <linux/thread_info.h>
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#include <linux/thread_info.h>
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@ -138,13 +139,26 @@ __copy_to_user(void __user *to, const void *from, unsigned long n)
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return raw_copy_to_user(to, from, n);
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return raw_copy_to_user(to, from, n);
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}
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}
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#ifdef INLINE_COPY_FROM_USER
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/*
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* Architectures that #define INLINE_COPY_TO_USER use this function
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* directly in the normal copy_to/from_user(), the other ones go
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* through an extern _copy_to/from_user(), which expands the same code
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* here.
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*
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* Rust code always uses the extern definition.
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*/
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static inline __must_check unsigned long
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static inline __must_check unsigned long
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_copy_from_user(void *to, const void __user *from, unsigned long n)
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_inline_copy_from_user(void *to, const void __user *from, unsigned long n)
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{
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{
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unsigned long res = n;
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unsigned long res = n;
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might_fault();
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might_fault();
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if (!should_fail_usercopy() && likely(access_ok(from, n))) {
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if (!should_fail_usercopy() && likely(access_ok(from, n))) {
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/*
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* Ensure that bad access_ok() speculation will not
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* lead to nasty side effects *after* the copy is
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* finished:
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*/
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barrier_nospec();
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instrument_copy_from_user_before(to, from, n);
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instrument_copy_from_user_before(to, from, n);
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res = raw_copy_from_user(to, from, n);
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res = raw_copy_from_user(to, from, n);
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instrument_copy_from_user_after(to, from, n, res);
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instrument_copy_from_user_after(to, from, n, res);
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@ -153,14 +167,11 @@ _copy_from_user(void *to, const void __user *from, unsigned long n)
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memset(to + (n - res), 0, res);
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memset(to + (n - res), 0, res);
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return res;
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return res;
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}
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}
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#else
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extern __must_check unsigned long
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extern __must_check unsigned long
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_copy_from_user(void *, const void __user *, 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 __must_check unsigned long
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static inline __must_check unsigned long
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_copy_to_user(void __user *to, const void *from, unsigned long n)
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_inline_copy_to_user(void __user *to, const void *from, unsigned long n)
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{
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{
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might_fault();
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might_fault();
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if (should_fail_usercopy())
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if (should_fail_usercopy())
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@ -171,25 +182,32 @@ _copy_to_user(void __user *to, const void *from, unsigned long n)
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}
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}
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return n;
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return n;
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}
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}
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#else
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extern __must_check unsigned long
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extern __must_check unsigned long
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_copy_to_user(void __user *, const void *, 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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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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copy_from_user(void *to, const void __user *from, unsigned long n)
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{
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{
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if (check_copy_size(to, n, false))
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if (!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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return n;
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#ifdef INLINE_COPY_FROM_USER
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return _inline_copy_from_user(to, from, n);
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#else
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return _copy_from_user(to, from, n);
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#endif
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}
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}
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static __always_inline unsigned long __must_check
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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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copy_to_user(void __user *to, const void *from, unsigned long n)
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{
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{
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if (check_copy_size(from, n, true))
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if (!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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return n;
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#ifdef INLINE_COPY_TO_USER
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return _inline_copy_to_user(to, from, n);
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#else
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return _copy_to_user(to, from, n);
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#endif
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}
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}
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#ifndef copy_mc_to_kernel
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#ifndef copy_mc_to_kernel
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@ -12,40 +12,18 @@
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/* out-of-line parts */
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/* out-of-line parts */
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#ifndef INLINE_COPY_FROM_USER
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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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unsigned long _copy_from_user(void *to, const void __user *from, unsigned long n)
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{
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{
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unsigned long res = n;
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return _inline_copy_from_user(to, from, n);
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might_fault();
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if (!should_fail_usercopy() && likely(access_ok(from, n))) {
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/*
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* Ensure that bad access_ok() speculation will not
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* lead to nasty side effects *after* the copy is
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* finished:
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*/
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barrier_nospec();
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instrument_copy_from_user_before(to, from, n);
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res = raw_copy_from_user(to, from, n);
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instrument_copy_from_user_after(to, from, n, res);
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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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}
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EXPORT_SYMBOL(_copy_from_user);
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EXPORT_SYMBOL(_copy_from_user);
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#endif
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#endif
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#ifndef INLINE_COPY_TO_USER
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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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unsigned long _copy_to_user(void __user *to, const void *from, unsigned long n)
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{
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{
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might_fault();
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return _inline_copy_to_user(to, from, n);
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if (should_fail_usercopy())
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return n;
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if (likely(access_ok(to, n))) {
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instrument_copy_to_user(to, 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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}
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EXPORT_SYMBOL(_copy_to_user);
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EXPORT_SYMBOL(_copy_to_user);
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#endif
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#endif
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