x86/extable: Introduce _ASM_EXTABLE_UA for uaccess fixups

Currently, most fixups for attempting to access userspace memory are
handled using _ASM_EXTABLE, which is also used for various other types of
fixups (e.g. safe MSR access, IRET failures, and a bunch of other things).
In order to make it possible to add special safety checks to uaccess fixups
(in particular, checking whether the fault address is actually in
userspace), introduce a new exception table handler ex_handler_uaccess()
and wire it up to all the user access fixups (excluding ones that
already use _ASM_EXTABLE_EX).

Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Kees Cook <keescook@chromium.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: kernel-hardening@lists.openwall.com
Cc: dvyukov@google.com
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Cc: Borislav Petkov <bp@alien8.de>
Link: https://lkml.kernel.org/r/20180828201421.157735-5-jannh@google.com

7 files changed, 129 insertions, 125 deletions

diff --git a/arch/x86/lib/checksum_32.S b/arch/x86/lib/checksum_32.S
index 46e71a74e612..ad8e0906d1ea 100644
--- a/arch/x86/lib/checksum_32.S
+++ b/arch/x86/lib/checksum_32.S
@@ -273,11 +273,11 @@ unsigned int csum_partial_copy_generic (const char *src, char *dst,
 
 #define SRC(y...)			\
 	9999: y;			\
-	_ASM_EXTABLE(9999b, 6001f)
+	_ASM_EXTABLE_UA(9999b, 6001f)
 
 #define DST(y...)			\
 	9999: y;			\
-	_ASM_EXTABLE(9999b, 6002f)
+	_ASM_EXTABLE_UA(9999b, 6002f)
 
 #ifndef CONFIG_X86_USE_PPRO_CHECKSUM
 
diff --git a/arch/x86/lib/copy_user_64.S b/arch/x86/lib/copy_user_64.S
index 020f75cc8cf6..db4e5aa0858b 100644
--- a/arch/x86/lib/copy_user_64.S
+++ b/arch/x86/lib/copy_user_64.S
@@ -92,26 +92,26 @@ ENTRY(copy_user_generic_unrolled)
 60:	jmp copy_user_handle_tail /* ecx is zerorest also */
 	.previous
 
-	_ASM_EXTABLE(1b,30b)
-	_ASM_EXTABLE(2b,30b)
-	_ASM_EXTABLE(3b,30b)
-	_ASM_EXTABLE(4b,30b)
-	_ASM_EXTABLE(5b,30b)
-	_ASM_EXTABLE(6b,30b)
-	_ASM_EXTABLE(7b,30b)
-	_ASM_EXTABLE(8b,30b)
-	_ASM_EXTABLE(9b,30b)
-	_ASM_EXTABLE(10b,30b)
-	_ASM_EXTABLE(11b,30b)
-	_ASM_EXTABLE(12b,30b)
-	_ASM_EXTABLE(13b,30b)
-	_ASM_EXTABLE(14b,30b)
-	_ASM_EXTABLE(15b,30b)
-	_ASM_EXTABLE(16b,30b)
-	_ASM_EXTABLE(18b,40b)
-	_ASM_EXTABLE(19b,40b)
-	_ASM_EXTABLE(21b,50b)
-	_ASM_EXTABLE(22b,50b)
+	_ASM_EXTABLE_UA(1b, 30b)
+	_ASM_EXTABLE_UA(2b, 30b)
+	_ASM_EXTABLE_UA(3b, 30b)
+	_ASM_EXTABLE_UA(4b, 30b)
+	_ASM_EXTABLE_UA(5b, 30b)
+	_ASM_EXTABLE_UA(6b, 30b)
+	_ASM_EXTABLE_UA(7b, 30b)
+	_ASM_EXTABLE_UA(8b, 30b)
+	_ASM_EXTABLE_UA(9b, 30b)
+	_ASM_EXTABLE_UA(10b, 30b)
+	_ASM_EXTABLE_UA(11b, 30b)
+	_ASM_EXTABLE_UA(12b, 30b)
+	_ASM_EXTABLE_UA(13b, 30b)
+	_ASM_EXTABLE_UA(14b, 30b)
+	_ASM_EXTABLE_UA(15b, 30b)
+	_ASM_EXTABLE_UA(16b, 30b)
+	_ASM_EXTABLE_UA(18b, 40b)
+	_ASM_EXTABLE_UA(19b, 40b)
+	_ASM_EXTABLE_UA(21b, 50b)
+	_ASM_EXTABLE_UA(22b, 50b)
 ENDPROC(copy_user_generic_unrolled)
 EXPORT_SYMBOL(copy_user_generic_unrolled)
 
@@ -156,8 +156,8 @@ ENTRY(copy_user_generic_string)
 	jmp copy_user_handle_tail
 	.previous
 
-	_ASM_EXTABLE(1b,11b)
-	_ASM_EXTABLE(3b,12b)
+	_ASM_EXTABLE_UA(1b, 11b)
+	_ASM_EXTABLE_UA(3b, 12b)
 ENDPROC(copy_user_generic_string)
 EXPORT_SYMBOL(copy_user_generic_string)
 
@@ -189,7 +189,7 @@ ENTRY(copy_user_enhanced_fast_string)
 	jmp copy_user_handle_tail
 	.previous
 
-	_ASM_EXTABLE(1b,12b)
+	_ASM_EXTABLE_UA(1b, 12b)
 ENDPROC(copy_user_enhanced_fast_string)
 EXPORT_SYMBOL(copy_user_enhanced_fast_string)
 
@@ -319,27 +319,27 @@ ENTRY(__copy_user_nocache)
 	jmp copy_user_handle_tail
 	.previous
 
-	_ASM_EXTABLE(1b,.L_fixup_4x8b_copy)
-	_ASM_EXTABLE(2b,.L_fixup_4x8b_copy)
-	_ASM_EXTABLE(3b,.L_fixup_4x8b_copy)
-	_ASM_EXTABLE(4b,.L_fixup_4x8b_copy)
-	_ASM_EXTABLE(5b,.L_fixup_4x8b_copy)
-	_ASM_EXTABLE(6b,.L_fixup_4x8b_copy)
-	_ASM_EXTABLE(7b,.L_fixup_4x8b_copy)
-	_ASM_EXTABLE(8b,.L_fixup_4x8b_copy)
-	_ASM_EXTABLE(9b,.L_fixup_4x8b_copy)
-	_ASM_EXTABLE(10b,.L_fixup_4x8b_copy)
-	_ASM_EXTABLE(11b,.L_fixup_4x8b_copy)
-	_ASM_EXTABLE(12b,.L_fixup_4x8b_copy)
-	_ASM_EXTABLE(13b,.L_fixup_4x8b_copy)
-	_ASM_EXTABLE(14b,.L_fixup_4x8b_copy)
-	_ASM_EXTABLE(15b,.L_fixup_4x8b_copy)
-	_ASM_EXTABLE(16b,.L_fixup_4x8b_copy)
-	_ASM_EXTABLE(20b,.L_fixup_8b_copy)
-	_ASM_EXTABLE(21b,.L_fixup_8b_copy)
-	_ASM_EXTABLE(30b,.L_fixup_4b_copy)
-	_ASM_EXTABLE(31b,.L_fixup_4b_copy)
-	_ASM_EXTABLE(40b,.L_fixup_1b_copy)
-	_ASM_EXTABLE(41b,.L_fixup_1b_copy)
+	_ASM_EXTABLE_UA(1b, .L_fixup_4x8b_copy)
+	_ASM_EXTABLE_UA(2b, .L_fixup_4x8b_copy)
+	_ASM_EXTABLE_UA(3b, .L_fixup_4x8b_copy)
+	_ASM_EXTABLE_UA(4b, .L_fixup_4x8b_copy)
+	_ASM_EXTABLE_UA(5b, .L_fixup_4x8b_copy)
+	_ASM_EXTABLE_UA(6b, .L_fixup_4x8b_copy)
+	_ASM_EXTABLE_UA(7b, .L_fixup_4x8b_copy)
+	_ASM_EXTABLE_UA(8b, .L_fixup_4x8b_copy)
+	_ASM_EXTABLE_UA(9b, .L_fixup_4x8b_copy)
+	_ASM_EXTABLE_UA(10b, .L_fixup_4x8b_copy)
+	_ASM_EXTABLE_UA(11b, .L_fixup_4x8b_copy)
+	_ASM_EXTABLE_UA(12b, .L_fixup_4x8b_copy)
+	_ASM_EXTABLE_UA(13b, .L_fixup_4x8b_copy)
+	_ASM_EXTABLE_UA(14b, .L_fixup_4x8b_copy)
+	_ASM_EXTABLE_UA(15b, .L_fixup_4x8b_copy)
+	_ASM_EXTABLE_UA(16b, .L_fixup_4x8b_copy)
+	_ASM_EXTABLE_UA(20b, .L_fixup_8b_copy)
+	_ASM_EXTABLE_UA(21b, .L_fixup_8b_copy)
+	_ASM_EXTABLE_UA(30b, .L_fixup_4b_copy)
+	_ASM_EXTABLE_UA(31b, .L_fixup_4b_copy)
+	_ASM_EXTABLE_UA(40b, .L_fixup_1b_copy)
+	_ASM_EXTABLE_UA(41b, .L_fixup_1b_copy)
 ENDPROC(__copy_user_nocache)
 EXPORT_SYMBOL(__copy_user_nocache)
diff --git a/arch/x86/lib/csum-copy_64.S b/arch/x86/lib/csum-copy_64.S
index 45a53dfe1859..a4a379e79259 100644
--- a/arch/x86/lib/csum-copy_64.S
+++ b/arch/x86/lib/csum-copy_64.S
@@ -31,14 +31,18 @@
 
 	.macro source
 10:
-	_ASM_EXTABLE(10b, .Lbad_source)
+	_ASM_EXTABLE_UA(10b, .Lbad_source)
 	.endm
 
 	.macro dest
 20:
-	_ASM_EXTABLE(20b, .Lbad_dest)
+	_ASM_EXTABLE_UA(20b, .Lbad_dest)
 	.endm
 
+	/*
+	 * No _ASM_EXTABLE_UA; this is used for intentional prefetch on a
+	 * potentially unmapped kernel address.
+	 */
 	.macro ignore L=.Lignore
 30:
 	_ASM_EXTABLE(30b, \L)
diff --git a/arch/x86/lib/getuser.S b/arch/x86/lib/getuser.S
index 49b167f73215..74fdff968ea3 100644
--- a/arch/x86/lib/getuser.S
+++ b/arch/x86/lib/getuser.S
@@ -132,12 +132,12 @@ bad_get_user_8:
 END(bad_get_user_8)
 #endif
 
-	_ASM_EXTABLE(1b,bad_get_user)
-	_ASM_EXTABLE(2b,bad_get_user)
-	_ASM_EXTABLE(3b,bad_get_user)
+	_ASM_EXTABLE_UA(1b, bad_get_user)
+	_ASM_EXTABLE_UA(2b, bad_get_user)
+	_ASM_EXTABLE_UA(3b, bad_get_user)
 #ifdef CONFIG_X86_64
-	_ASM_EXTABLE(4b,bad_get_user)
+	_ASM_EXTABLE_UA(4b, bad_get_user)
 #else
-	_ASM_EXTABLE(4b,bad_get_user_8)
-	_ASM_EXTABLE(5b,bad_get_user_8)
+	_ASM_EXTABLE_UA(4b, bad_get_user_8)
+	_ASM_EXTABLE_UA(5b, bad_get_user_8)
 #endif
diff --git a/arch/x86/lib/putuser.S b/arch/x86/lib/putuser.S
index 96dce5fe2a35..d2e5c9c39601 100644
--- a/arch/x86/lib/putuser.S
+++ b/arch/x86/lib/putuser.S
@@ -94,10 +94,10 @@ bad_put_user:
 	EXIT
 END(bad_put_user)
 
-	_ASM_EXTABLE(1b,bad_put_user)
-	_ASM_EXTABLE(2b,bad_put_user)
-	_ASM_EXTABLE(3b,bad_put_user)
-	_ASM_EXTABLE(4b,bad_put_user)
+	_ASM_EXTABLE_UA(1b, bad_put_user)
+	_ASM_EXTABLE_UA(2b, bad_put_user)
+	_ASM_EXTABLE_UA(3b, bad_put_user)
+	_ASM_EXTABLE_UA(4b, bad_put_user)
 #ifdef CONFIG_X86_32
-	_ASM_EXTABLE(5b,bad_put_user)
+	_ASM_EXTABLE_UA(5b, bad_put_user)
 #endif
diff --git a/arch/x86/lib/usercopy_32.c b/arch/x86/lib/usercopy_32.c
index 7add8ba06887..71fb58d44d58 100644
--- a/arch/x86/lib/usercopy_32.c
+++ b/arch/x86/lib/usercopy_32.c
@@ -47,8 +47,8 @@ do {									\
 		"3:	lea 0(%2,%0,4),%0\n"				\
 		"	jmp 2b\n"					\
 		".previous\n"						\
-		_ASM_EXTABLE(0b,3b)					\
-		_ASM_EXTABLE(1b,2b)					\
+		_ASM_EXTABLE_UA(0b, 3b)					\
+		_ASM_EXTABLE_UA(1b, 2b)					\
 		: "=&c"(size), "=&D" (__d0)				\
 		: "r"(size & 3), "0"(size / 4), "1"(addr), "a"(0));	\
 } while (0)
@@ -153,44 +153,44 @@ __copy_user_intel(void __user *to, const void *from, unsigned long size)
 		       "101:   lea 0(%%eax,%0,4),%0\n"
 		       "       jmp 100b\n"
 		       ".previous\n"
-		       _ASM_EXTABLE(1b,100b)
-		       _ASM_EXTABLE(2b,100b)
-		       _ASM_EXTABLE(3b,100b)
-		       _ASM_EXTABLE(4b,100b)
-		       _ASM_EXTABLE(5b,100b)
-		       _ASM_EXTABLE(6b,100b)
-		       _ASM_EXTABLE(7b,100b)
-		       _ASM_EXTABLE(8b,100b)
-		       _ASM_EXTABLE(9b,100b)
-		       _ASM_EXTABLE(10b,100b)
-		       _ASM_EXTABLE(11b,100b)
-		       _ASM_EXTABLE(12b,100b)
-		       _ASM_EXTABLE(13b,100b)
-		       _ASM_EXTABLE(14b,100b)
-		       _ASM_EXTABLE(15b,100b)
-		       _ASM_EXTABLE(16b,100b)
-		       _ASM_EXTABLE(17b,100b)
-		       _ASM_EXTABLE(18b,100b)
-		       _ASM_EXTABLE(19b,100b)
-		       _ASM_EXTABLE(20b,100b)
-		       _ASM_EXTABLE(21b,100b)
-		       _ASM_EXTABLE(22b,100b)
-		       _ASM_EXTABLE(23b,100b)
-		       _ASM_EXTABLE(24b,100b)
-		       _ASM_EXTABLE(25b,100b)
-		       _ASM_EXTABLE(26b,100b)
-		       _ASM_EXTABLE(27b,100b)
-		       _ASM_EXTABLE(28b,100b)
-		       _ASM_EXTABLE(29b,100b)
-		       _ASM_EXTABLE(30b,100b)
-		       _ASM_EXTABLE(31b,100b)
-		       _ASM_EXTABLE(32b,100b)
-		       _ASM_EXTABLE(33b,100b)
-		       _ASM_EXTABLE(34b,100b)
-		       _ASM_EXTABLE(35b,100b)
-		       _ASM_EXTABLE(36b,100b)
-		       _ASM_EXTABLE(37b,100b)
-		       _ASM_EXTABLE(99b,101b)
+		       _ASM_EXTABLE_UA(1b, 100b)
+		       _ASM_EXTABLE_UA(2b, 100b)
+		       _ASM_EXTABLE_UA(3b, 100b)
+		       _ASM_EXTABLE_UA(4b, 100b)
+		       _ASM_EXTABLE_UA(5b, 100b)
+		       _ASM_EXTABLE_UA(6b, 100b)
+		       _ASM_EXTABLE_UA(7b, 100b)
+		       _ASM_EXTABLE_UA(8b, 100b)
+		       _ASM_EXTABLE_UA(9b, 100b)
+		       _ASM_EXTABLE_UA(10b, 100b)
+		       _ASM_EXTABLE_UA(11b, 100b)
+		       _ASM_EXTABLE_UA(12b, 100b)
+		       _ASM_EXTABLE_UA(13b, 100b)
+		       _ASM_EXTABLE_UA(14b, 100b)
+		       _ASM_EXTABLE_UA(15b, 100b)
+		       _ASM_EXTABLE_UA(16b, 100b)
+		       _ASM_EXTABLE_UA(17b, 100b)
+		       _ASM_EXTABLE_UA(18b, 100b)
+		       _ASM_EXTABLE_UA(19b, 100b)
+		       _ASM_EXTABLE_UA(20b, 100b)
+		       _ASM_EXTABLE_UA(21b, 100b)
+		       _ASM_EXTABLE_UA(22b, 100b)
+		       _ASM_EXTABLE_UA(23b, 100b)
+		       _ASM_EXTABLE_UA(24b, 100b)
+		       _ASM_EXTABLE_UA(25b, 100b)
+		       _ASM_EXTABLE_UA(26b, 100b)
+		       _ASM_EXTABLE_UA(27b, 100b)
+		       _ASM_EXTABLE_UA(28b, 100b)
+		       _ASM_EXTABLE_UA(29b, 100b)
+		       _ASM_EXTABLE_UA(30b, 100b)
+		       _ASM_EXTABLE_UA(31b, 100b)
+		       _ASM_EXTABLE_UA(32b, 100b)
+		       _ASM_EXTABLE_UA(33b, 100b)
+		       _ASM_EXTABLE_UA(34b, 100b)
+		       _ASM_EXTABLE_UA(35b, 100b)
+		       _ASM_EXTABLE_UA(36b, 100b)
+		       _ASM_EXTABLE_UA(37b, 100b)
+		       _ASM_EXTABLE_UA(99b, 101b)
 		       : "=&c"(size), "=&D" (d0), "=&S" (d1)
 		       :  "1"(to), "2"(from), "0"(size)
 		       : "eax", "edx", "memory");
@@ -259,26 +259,26 @@ static unsigned long __copy_user_intel_nocache(void *to,
 	       "9:      lea 0(%%eax,%0,4),%0\n"
 	       "16:     jmp 8b\n"
 	       ".previous\n"
-	       _ASM_EXTABLE(0b,16b)
-	       _ASM_EXTABLE(1b,16b)
-	       _ASM_EXTABLE(2b,16b)
-	       _ASM_EXTABLE(21b,16b)
-	       _ASM_EXTABLE(3b,16b)
-	       _ASM_EXTABLE(31b,16b)
-	       _ASM_EXTABLE(4b,16b)
-	       _ASM_EXTABLE(41b,16b)
-	       _ASM_EXTABLE(10b,16b)
-	       _ASM_EXTABLE(51b,16b)
-	       _ASM_EXTABLE(11b,16b)
-	       _ASM_EXTABLE(61b,16b)
-	       _ASM_EXTABLE(12b,16b)
-	       _ASM_EXTABLE(71b,16b)
-	       _ASM_EXTABLE(13b,16b)
-	       _ASM_EXTABLE(81b,16b)
-	       _ASM_EXTABLE(14b,16b)
-	       _ASM_EXTABLE(91b,16b)
-	       _ASM_EXTABLE(6b,9b)
-	       _ASM_EXTABLE(7b,16b)
+	       _ASM_EXTABLE_UA(0b, 16b)
+	       _ASM_EXTABLE_UA(1b, 16b)
+	       _ASM_EXTABLE_UA(2b, 16b)
+	       _ASM_EXTABLE_UA(21b, 16b)
+	       _ASM_EXTABLE_UA(3b, 16b)
+	       _ASM_EXTABLE_UA(31b, 16b)
+	       _ASM_EXTABLE_UA(4b, 16b)
+	       _ASM_EXTABLE_UA(41b, 16b)
+	       _ASM_EXTABLE_UA(10b, 16b)
+	       _ASM_EXTABLE_UA(51b, 16b)
+	       _ASM_EXTABLE_UA(11b, 16b)
+	       _ASM_EXTABLE_UA(61b, 16b)
+	       _ASM_EXTABLE_UA(12b, 16b)
+	       _ASM_EXTABLE_UA(71b, 16b)
+	       _ASM_EXTABLE_UA(13b, 16b)
+	       _ASM_EXTABLE_UA(81b, 16b)
+	       _ASM_EXTABLE_UA(14b, 16b)
+	       _ASM_EXTABLE_UA(91b, 16b)
+	       _ASM_EXTABLE_UA(6b, 9b)
+	       _ASM_EXTABLE_UA(7b, 16b)
 	       : "=&c"(size), "=&D" (d0), "=&S" (d1)
 	       :  "1"(to), "2"(from), "0"(size)
 	       : "eax", "edx", "memory");
@@ -321,9 +321,9 @@ do {									\
 		"3:	lea 0(%3,%0,4),%0\n"				\
 		"	jmp 2b\n"					\
 		".previous\n"						\
-		_ASM_EXTABLE(4b,5b)					\
-		_ASM_EXTABLE(0b,3b)					\
-		_ASM_EXTABLE(1b,2b)					\
+		_ASM_EXTABLE_UA(4b, 5b)					\
+		_ASM_EXTABLE_UA(0b, 3b)					\
+		_ASM_EXTABLE_UA(1b, 2b)					\
 		: "=&c"(size), "=&D" (__d0), "=&S" (__d1), "=r"(__d2)	\
 		: "3"(size), "0"(size), "1"(to), "2"(from)		\
 		: "memory");						\
diff --git a/arch/x86/lib/usercopy_64.c b/arch/x86/lib/usercopy_64.c
index 9c5606d88f61..fefe64436398 100644
--- a/arch/x86/lib/usercopy_64.c
+++ b/arch/x86/lib/usercopy_64.c
@@ -37,8 +37,8 @@ unsigned long __clear_user(void __user *addr, unsigned long size)
 		"3:	lea 0(%[size1],%[size8],8),%[size8]\n"
 		"	jmp 2b\n"
 		".previous\n"
-		_ASM_EXTABLE(0b,3b)
-		_ASM_EXTABLE(1b,2b)
+		_ASM_EXTABLE_UA(0b, 3b)
+		_ASM_EXTABLE_UA(1b, 2b)
 		: [size8] "=&c"(size), [dst] "=&D" (__d0)
 		: [size1] "r"(size & 7), "[size8]" (size / 8), "[dst]"(addr));
 	clac();