x86/uaccess: Enable hardened usercopy

Enables CONFIG_HARDENED_USERCOPY checks on x86. This is done both in
copy_*_user() and __copy_*_user() because copy_*_user() actually calls
down to _copy_*_user() and not __copy_*_user().

Based on code from PaX and grsecurity.

Signed-off-by: Kees Cook <keescook@chromium.org>
Tested-by: Valdis Kletnieks <valdis.kletnieks@vt.edu>

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index a2865dd..9640942 100644 (file)
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -80,6 +80,7 @@ config X86
        select HAVE_ALIGNED_STRUCT_PAGE         if SLUB
        select HAVE_AOUT                        if X86_32
        select HAVE_ARCH_AUDITSYSCALL
+       select HAVE_ARCH_HARDENED_USERCOPY
        select HAVE_ARCH_HUGE_VMAP              if X86_64 || X86_PAE
        select HAVE_ARCH_JUMP_LABEL
        select HAVE_ARCH_KASAN                  if X86_64 && SPARSEMEM_VMEMMAP

diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h
index 2982387..d3312f0 100644 (file)
--- a/arch/x86/include/asm/uaccess.h
+++ b/arch/x86/include/asm/uaccess.h
@@ -742,9 +742,10 @@ copy_from_user(void *to, const void __user *from, unsigned long n)
         * case, and do only runtime checking for non-constant sizes.
         */
 
-       if (likely(sz < 0 || sz >= n))
+       if (likely(sz < 0 || sz >= n)) {
+               check_object_size(to, n, false);
                n = _copy_from_user(to, from, n);
-       else if(__builtin_constant_p(n))
+       } else if (__builtin_constant_p(n))
                copy_from_user_overflow();
        else
                __copy_from_user_overflow(sz, n);
@@ -762,9 +763,10 @@ copy_to_user(void __user *to, const void *from, unsigned long n)
        might_fault();
 
        /* See the comment in copy_from_user() above. */
-       if (likely(sz < 0 || sz >= n))
+       if (likely(sz < 0 || sz >= n)) {
+               check_object_size(from, n, true);
                n = _copy_to_user(to, from, n);
-       else if(__builtin_constant_p(n))
+       } else if (__builtin_constant_p(n))
                copy_to_user_overflow();
        else
                __copy_to_user_overflow(sz, n);

diff --git a/arch/x86/include/asm/uaccess_32.h b/arch/x86/include/asm/uaccess_32.h
index 4b32da2..7d3bdd1 100644 (file)
--- a/arch/x86/include/asm/uaccess_32.h
+++ b/arch/x86/include/asm/uaccess_32.h
@@ -37,6 +37,7 @@ unsigned long __must_check __copy_from_user_ll_nocache_nozero
 static __always_inline unsigned long __must_check
 __copy_to_user_inatomic(void __user *to, const void *from, unsigned long n)
 {
+       check_object_size(from, n, true);
        return __copy_to_user_ll(to, from, n);
 }
 
@@ -95,6 +96,7 @@ static __always_inline unsigned long
 __copy_from_user(void *to, const void __user *from, unsigned long n)
 {
        might_fault();
+       check_object_size(to, n, false);
        if (__builtin_constant_p(n)) {
                unsigned long ret;
 

diff --git a/arch/x86/include/asm/uaccess_64.h b/arch/x86/include/asm/uaccess_64.h
index 2eac2aa..673059a 100644 (file)
--- a/arch/x86/include/asm/uaccess_64.h
+++ b/arch/x86/include/asm/uaccess_64.h
@@ -54,6 +54,7 @@ int __copy_from_user_nocheck(void *dst, const void __user *src, unsigned size)
 {
        int ret = 0;
 
+       check_object_size(dst, size, false);
        if (!__builtin_constant_p(size))
                return copy_user_generic(dst, (__force void *)src, size);
        switch (size) {
@@ -119,6 +120,7 @@ int __copy_to_user_nocheck(void __user *dst, const void *src, unsigned size)
 {
        int ret = 0;
 
+       check_object_size(src, size, true);
        if (!__builtin_constant_p(size))
                return copy_user_generic((__force void *)dst, src, size);
        switch (size) {