On Wed, Jul 23, 2014 at 8:40 PM, Andy Lutomirski [off-list ref] wrote:

On 07/22/2014 02:14 AM, AKASHI Takahiro wrote:

quoted

Those values (__NR_seccomp_*) are used solely in secure_computing()
to identify mode 1 system calls. If compat system calls have different
syscall numbers, asm/seccomp.h may override them.

Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: AKASHI Takahiro <redacted>
---
  include/asm-generic/seccomp.h |   28 ++++++++++++++++++++++++++++
  1 file changed, 28 insertions(+)
  create mode 100644 include/asm-generic/seccomp.h

diff --git a/include/asm-generic/seccomp.h b/include/asm-generic/seccomp.h
new file mode 100644
index 0000000..5e97022
--- /dev/null
+++ b/include/asm-generic/seccomp.h

@@ -0,0 +1,28 @@
+/*
+ * include/asm-generic/seccomp.h
+ *
+ * Copyright (C) 2014 Linaro Limited
+ * Author: AKASHI Takahiro <takahiro.akashi@linaro.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#ifndef _ASM_GENERIC_SECCOMP_H
+#define _ASM_GENERIC_SECCOMP_H
+
+#include <asm-generic/unistd.h>
+
+#if defined(CONFIG_COMPAT) && !defined(__NR_seccomp_read_32)
+#define __NR_seccomp_read_32           __NR_read
+#define __NR_seccomp_write_32          __NR_write
+#define __NR_seccomp_exit_32           __NR_exit
+#define __NR_seccomp_sigreturn_32      __NR_rt_sigreturn
+#endif /* CONFIG_COMPAT && ! already defined */
+
+#define __NR_seccomp_read              __NR_read
+#define __NR_seccomp_write             __NR_write
+#define __NR_seccomp_exit              __NR_exit
+#define __NR_seccomp_sigreturn         __NR_rt_sigreturn

I don't like these names.  __NR_seccomp_read sounds like the number of a
syscall called seccomp_read.

Also, shouldn't something be including this header?  I'm confused.

Ah! Good catch. These names are correct (see kernel/seccomp.c's
mode1_syscalls and mode1_syscalls_32 arrays), but the location of this
change was unexpected. I was expecting this file to live in
arch/*/include/asm/seccomp.h, not in include/asm-generic/seccomp.h.

However, since it's always the same list, it might make sense to
consolidate them into a single place as a default to make arch porting
easier. However, I think that should be a separate patch.

-Kees

-- 
Kees Cook
Chrome OS Security