copy_{to,from}_user(): consolidate object size checks

... and move them into thread_info.h, next to check_object_size()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/include/linux/thread_info.h b/include/linux/thread_info.h
index d7d3ea637dd0a500875cbe64c00eb5e0188acd41..250a27614328471e4a805884a952881116a14c3e 100644 (file)
--- a/include/linux/thread_info.h
+++ b/include/linux/thread_info.h
@@ -113,6 +113,33 @@ static inline void check_object_size(const void *ptr, unsigned long n,
 { }
 #endif /* CONFIG_HARDENED_USERCOPY */
 
+extern void __compiletime_error("copy source size is too small")
+__bad_copy_from(void);
+extern void __compiletime_error("copy destination size is too small")
+__bad_copy_to(void);
+
+static inline void copy_overflow(int size, unsigned long count)
+{
+       WARN(1, "Buffer overflow detected (%d < %lu)!\n", size, count);
+}
+
+static __always_inline bool
+check_copy_size(const void *addr, size_t bytes, bool is_source)
+{
+       int sz = __compiletime_object_size(addr);
+       if (unlikely(sz >= 0 && sz < bytes)) {
+               if (!__builtin_constant_p(bytes))
+                       copy_overflow(sz, bytes);
+               else if (is_source)
+                       __bad_copy_from();
+               else
+                       __bad_copy_to();
+               return false;
+       }
+       check_object_size(addr, bytes, is_source);
+       return true;
+}
+
 #ifndef arch_setup_new_exec
 static inline void arch_setup_new_exec(void) { }
 #endif

diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h
index e57328896a16ae43bfd5882b1a4e3f272e675dd1..80b587085e7913c19ab17d33a1a1ff77e51ad7ad 100644 (file)
--- a/include/linux/uaccess.h
+++ b/include/linux/uaccess.h
@@ -139,43 +139,19 @@ extern unsigned long
 _copy_to_user(void __user *, const void *, unsigned long);
 #endif
 
-extern void __compiletime_error("usercopy buffer size is too small")
-__bad_copy_user(void);
-
-static inline void copy_user_overflow(int size, unsigned long count)
-{
-       WARN(1, "Buffer overflow detected (%d < %lu)!\n", size, count);
-}
-
 static __always_inline unsigned long __must_check
 copy_from_user(void *to, const void __user *from, unsigned long n)
 {
-       int sz = __compiletime_object_size(to);
-
-       if (likely(sz < 0 || sz >= n)) {
-               check_object_size(to, n, false);
+       if (likely(check_copy_size(to, n, false)))
                n = _copy_from_user(to, from, n);
-       } else if (!__builtin_constant_p(n))
-               copy_user_overflow(sz, n);
-       else
-               __bad_copy_user();
-
        return n;
 }
 
 static __always_inline unsigned long __must_check
 copy_to_user(void __user *to, const void *from, unsigned long n)
 {
-       int sz = __compiletime_object_size(from);
-
-       if (likely(sz < 0 || sz >= n)) {
-               check_object_size(from, n, true);
+       if (likely(check_copy_size(from, n, true)))
                n = _copy_to_user(to, from, n);
-       } else if (!__builtin_constant_p(n))
-               copy_user_overflow(sz, n);
-       else
-               __bad_copy_user();
-
        return n;
 }
 #ifdef CONFIG_COMPAT