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* [PATCH v3 0/3] fix function type mismatches in syscall wrappers
@ 2019-05-24 22:11 Sami Tolvanen
  2019-05-24 22:11 ` [PATCH v3 1/3] arm64: fix syscall_fn_t type Sami Tolvanen
                   ` (3 more replies)
  0 siblings, 4 replies; 5+ messages in thread
From: Sami Tolvanen @ 2019-05-24 22:11 UTC (permalink / raw)
  To: Catalin Marinas, Will Deacon, Mark Rutland
  Cc: Kees Cook, Nick Desaulniers, linux-arm-kernel, linux-kernel,
	Sami Tolvanen

These patches fix type mismatches in arm64 syscall wrapper
definitions, which trip indirect call checks with Control-Flow
Integrity.

Changes in v3:
- instead of SYSCALL_DEFINE0, just define __arm64_sys_ni_syscall
  with the correct type to avoid unnecessary error injection

Changes in v2:
- more informative commit message for the syscall_fn_t change
- added a patch for fixing sys_ni_syscall

Sami Tolvanen (3):
  arm64: fix syscall_fn_t type
  arm64: use the correct function type in SYSCALL_DEFINE0
  arm64: use the correct function type for __arm64_sys_ni_syscall

 arch/arm64/include/asm/syscall.h         |  2 +-
 arch/arm64/include/asm/syscall_wrapper.h | 18 +++++++++---------
 arch/arm64/kernel/sys.c                  | 14 +++++++++-----
 arch/arm64/kernel/sys32.c                |  7 ++-----
 4 files changed, 21 insertions(+), 20 deletions(-)

-- 
2.22.0.rc1.257.g3120a18244-goog


^ permalink raw reply	[flat|nested] 5+ messages in thread

* [PATCH v3 1/3] arm64: fix syscall_fn_t type
  2019-05-24 22:11 [PATCH v3 0/3] fix function type mismatches in syscall wrappers Sami Tolvanen
@ 2019-05-24 22:11 ` Sami Tolvanen
  2019-05-24 22:11 ` [PATCH v3 2/3] arm64: use the correct function type in SYSCALL_DEFINE0 Sami Tolvanen
                   ` (2 subsequent siblings)
  3 siblings, 0 replies; 5+ messages in thread
From: Sami Tolvanen @ 2019-05-24 22:11 UTC (permalink / raw)
  To: Catalin Marinas, Will Deacon, Mark Rutland
  Cc: Kees Cook, Nick Desaulniers, linux-arm-kernel, linux-kernel,
	Sami Tolvanen

Syscall wrappers in <asm/syscall_wrapper.h> use const struct pt_regs *
as the argument type. Use const in syscall_fn_t as well to fix indirect
call type mismatches with Control-Flow Integrity checking.

Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
---
 arch/arm64/include/asm/syscall.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/include/asm/syscall.h b/arch/arm64/include/asm/syscall.h
index a65167f5cded8..e8bcb9ecede9b 100644
--- a/arch/arm64/include/asm/syscall.h
+++ b/arch/arm64/include/asm/syscall.h
@@ -20,7 +20,7 @@
 #include <linux/compat.h>
 #include <linux/err.h>
 
-typedef long (*syscall_fn_t)(struct pt_regs *regs);
+typedef long (*syscall_fn_t)(const struct pt_regs *regs);
 
 extern const syscall_fn_t sys_call_table[];
 
-- 
2.22.0.rc1.257.g3120a18244-goog


^ permalink raw reply	[flat|nested] 5+ messages in thread

* [PATCH v3 2/3] arm64: use the correct function type in SYSCALL_DEFINE0
  2019-05-24 22:11 [PATCH v3 0/3] fix function type mismatches in syscall wrappers Sami Tolvanen
  2019-05-24 22:11 ` [PATCH v3 1/3] arm64: fix syscall_fn_t type Sami Tolvanen
@ 2019-05-24 22:11 ` Sami Tolvanen
  2019-05-24 22:11 ` [PATCH v3 3/3] arm64: use the correct function type for __arm64_sys_ni_syscall Sami Tolvanen
  2019-05-29 15:09 ` [PATCH v3 0/3] fix function type mismatches in syscall wrappers Will Deacon
  3 siblings, 0 replies; 5+ messages in thread
From: Sami Tolvanen @ 2019-05-24 22:11 UTC (permalink / raw)
  To: Catalin Marinas, Will Deacon, Mark Rutland
  Cc: Kees Cook, Nick Desaulniers, linux-arm-kernel, linux-kernel,
	Sami Tolvanen

Although a syscall defined using SYSCALL_DEFINE0 doesn't accept
parameters, use the correct function type to avoid indirect call
type mismatches with Control-Flow Integrity checking.

Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
---
 arch/arm64/include/asm/syscall_wrapper.h | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/arch/arm64/include/asm/syscall_wrapper.h b/arch/arm64/include/asm/syscall_wrapper.h
index a4477e515b798..507d0ee6bc690 100644
--- a/arch/arm64/include/asm/syscall_wrapper.h
+++ b/arch/arm64/include/asm/syscall_wrapper.h
@@ -30,10 +30,10 @@
 	}										\
 	static inline long __do_compat_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__))
 
-#define COMPAT_SYSCALL_DEFINE0(sname)					\
-	asmlinkage long __arm64_compat_sys_##sname(void);		\
-	ALLOW_ERROR_INJECTION(__arm64_compat_sys_##sname, ERRNO);	\
-	asmlinkage long __arm64_compat_sys_##sname(void)
+#define COMPAT_SYSCALL_DEFINE0(sname)							\
+	asmlinkage long __arm64_compat_sys_##sname(const struct pt_regs *__unused);	\
+	ALLOW_ERROR_INJECTION(__arm64_compat_sys_##sname, ERRNO);			\
+	asmlinkage long __arm64_compat_sys_##sname(const struct pt_regs *__unused)
 
 #define COND_SYSCALL_COMPAT(name) \
 	cond_syscall(__arm64_compat_sys_##name);
@@ -62,11 +62,11 @@
 	static inline long __do_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__))
 
 #ifndef SYSCALL_DEFINE0
-#define SYSCALL_DEFINE0(sname)					\
-	SYSCALL_METADATA(_##sname, 0);				\
-	asmlinkage long __arm64_sys_##sname(void);		\
-	ALLOW_ERROR_INJECTION(__arm64_sys_##sname, ERRNO);	\
-	asmlinkage long __arm64_sys_##sname(void)
+#define SYSCALL_DEFINE0(sname)							\
+	SYSCALL_METADATA(_##sname, 0);						\
+	asmlinkage long __arm64_sys_##sname(const struct pt_regs *__unused);	\
+	ALLOW_ERROR_INJECTION(__arm64_sys_##sname, ERRNO);			\
+	asmlinkage long __arm64_sys_##sname(const struct pt_regs *__unused)
 #endif
 
 #ifndef COND_SYSCALL
-- 
2.22.0.rc1.257.g3120a18244-goog


^ permalink raw reply	[flat|nested] 5+ messages in thread

* [PATCH v3 3/3] arm64: use the correct function type for __arm64_sys_ni_syscall
  2019-05-24 22:11 [PATCH v3 0/3] fix function type mismatches in syscall wrappers Sami Tolvanen
  2019-05-24 22:11 ` [PATCH v3 1/3] arm64: fix syscall_fn_t type Sami Tolvanen
  2019-05-24 22:11 ` [PATCH v3 2/3] arm64: use the correct function type in SYSCALL_DEFINE0 Sami Tolvanen
@ 2019-05-24 22:11 ` Sami Tolvanen
  2019-05-29 15:09 ` [PATCH v3 0/3] fix function type mismatches in syscall wrappers Will Deacon
  3 siblings, 0 replies; 5+ messages in thread
From: Sami Tolvanen @ 2019-05-24 22:11 UTC (permalink / raw)
  To: Catalin Marinas, Will Deacon, Mark Rutland
  Cc: Kees Cook, Nick Desaulniers, linux-arm-kernel, linux-kernel,
	Sami Tolvanen

Calling sys_ni_syscall through a syscall_fn_t pointer trips indirect
call Control-Flow Integrity checking due to a function type
mismatch. Use SYSCALL_DEFINE0 for __arm64_sys_ni_syscall instead and
remove the now unnecessary casts.

Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
---
 arch/arm64/kernel/sys.c   | 14 +++++++++-----
 arch/arm64/kernel/sys32.c |  7 ++-----
 2 files changed, 11 insertions(+), 10 deletions(-)

diff --git a/arch/arm64/kernel/sys.c b/arch/arm64/kernel/sys.c
index 6f91e81165147..d8b35cfe5e94e 100644
--- a/arch/arm64/kernel/sys.c
+++ b/arch/arm64/kernel/sys.c
@@ -47,22 +47,26 @@ SYSCALL_DEFINE1(arm64_personality, unsigned int, personality)
 	return ksys_personality(personality);
 }
 
+asmlinkage long sys_ni_syscall(void);
+
+asmlinkage long __arm64_sys_ni_syscall(const struct pt_regs *__unused)
+{
+	return sys_ni_syscall();
+}
+
 /*
  * Wrappers to pass the pt_regs argument.
  */
 #define sys_personality		sys_arm64_personality
 
-asmlinkage long sys_ni_syscall(const struct pt_regs *);
-#define __arm64_sys_ni_syscall	sys_ni_syscall
-
 #undef __SYSCALL
 #define __SYSCALL(nr, sym)	asmlinkage long __arm64_##sym(const struct pt_regs *);
 #include <asm/unistd.h>
 
 #undef __SYSCALL
-#define __SYSCALL(nr, sym)	[nr] = (syscall_fn_t)__arm64_##sym,
+#define __SYSCALL(nr, sym)	[nr] = __arm64_##sym,
 
 const syscall_fn_t sys_call_table[__NR_syscalls] = {
-	[0 ... __NR_syscalls - 1] = (syscall_fn_t)sys_ni_syscall,
+	[0 ... __NR_syscalls - 1] = __arm64_sys_ni_syscall,
 #include <asm/unistd.h>
 };
diff --git a/arch/arm64/kernel/sys32.c b/arch/arm64/kernel/sys32.c
index 0f8bcb7de7008..3c80a40c1c9d6 100644
--- a/arch/arm64/kernel/sys32.c
+++ b/arch/arm64/kernel/sys32.c
@@ -133,17 +133,14 @@ COMPAT_SYSCALL_DEFINE6(aarch32_fallocate, int, fd, int, mode,
 	return ksys_fallocate(fd, mode, arg_u64(offset), arg_u64(len));
 }
 
-asmlinkage long sys_ni_syscall(const struct pt_regs *);
-#define __arm64_sys_ni_syscall	sys_ni_syscall
-
 #undef __SYSCALL
 #define __SYSCALL(nr, sym)	asmlinkage long __arm64_##sym(const struct pt_regs *);
 #include <asm/unistd32.h>
 
 #undef __SYSCALL
-#define __SYSCALL(nr, sym)	[nr] = (syscall_fn_t)__arm64_##sym,
+#define __SYSCALL(nr, sym)	[nr] = __arm64_##sym,
 
 const syscall_fn_t compat_sys_call_table[__NR_compat_syscalls] = {
-	[0 ... __NR_compat_syscalls - 1] = (syscall_fn_t)sys_ni_syscall,
+	[0 ... __NR_compat_syscalls - 1] = __arm64_sys_ni_syscall,
 #include <asm/unistd32.h>
 };
-- 
2.22.0.rc1.257.g3120a18244-goog


^ permalink raw reply	[flat|nested] 5+ messages in thread

* Re: [PATCH v3 0/3] fix function type mismatches in syscall wrappers
  2019-05-24 22:11 [PATCH v3 0/3] fix function type mismatches in syscall wrappers Sami Tolvanen
                   ` (2 preceding siblings ...)
  2019-05-24 22:11 ` [PATCH v3 3/3] arm64: use the correct function type for __arm64_sys_ni_syscall Sami Tolvanen
@ 2019-05-29 15:09 ` Will Deacon
  3 siblings, 0 replies; 5+ messages in thread
From: Will Deacon @ 2019-05-29 15:09 UTC (permalink / raw)
  To: Sami Tolvanen
  Cc: Catalin Marinas, Mark Rutland, Kees Cook, Nick Desaulniers,
	linux-arm-kernel, linux-kernel

On Fri, May 24, 2019 at 03:11:15PM -0700, Sami Tolvanen wrote:
> These patches fix type mismatches in arm64 syscall wrapper
> definitions, which trip indirect call checks with Control-Flow
> Integrity.
> 
> Changes in v3:
> - instead of SYSCALL_DEFINE0, just define __arm64_sys_ni_syscall
>   with the correct type to avoid unnecessary error injection

Thanks, I've picked this up for -rc3.

Will

^ permalink raw reply	[flat|nested] 5+ messages in thread

end of thread, other threads:[~2019-05-29 15:09 UTC | newest]

Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
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2019-05-24 22:11 [PATCH v3 0/3] fix function type mismatches in syscall wrappers Sami Tolvanen
2019-05-24 22:11 ` [PATCH v3 1/3] arm64: fix syscall_fn_t type Sami Tolvanen
2019-05-24 22:11 ` [PATCH v3 2/3] arm64: use the correct function type in SYSCALL_DEFINE0 Sami Tolvanen
2019-05-24 22:11 ` [PATCH v3 3/3] arm64: use the correct function type for __arm64_sys_ni_syscall Sami Tolvanen
2019-05-29 15:09 ` [PATCH v3 0/3] fix function type mismatches in syscall wrappers Will Deacon

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