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linux-next/arch/x86/include/asm/unistd.h
Andy Lutomirski 6365b842aa x86/syscalls: Split the x32 syscalls into their own table
For unfortunate historical reasons, the x32 syscalls and the x86_64
syscalls are not all numbered the same.  As an example, ioctl() is nr 16 on
x86_64 but 514 on x32.

This has potentially nasty consequences, since it means that there are two
valid RAX values to do ioctl(2) and two invalid RAX values.  The valid
values are 16 (i.e. ioctl(2) using the x86_64 ABI) and (514 | 0x40000000)
(i.e. ioctl(2) using the x32 ABI).

The invalid values are 514 and (16 | 0x40000000).  514 will enter the
"COMPAT_SYSCALL_DEFINE3(ioctl, ...)" entry point with in_compat_syscall()
and in_x32_syscall() returning false, whereas (16 | 0x40000000) will enter
the native entry point with in_compat_syscall() and in_x32_syscall()
returning true.  Both are bogus, and both will exercise code paths in the
kernel and in any running seccomp filters that really ought to be
unreachable.

Splitting out the x32 syscalls into their own tables, allows both bogus
invocations to return -ENOSYS.  I've checked glibc, musl, and Bionic, and
all of them appear to call syscalls with their correct numbers, so this
change should have no effect on them.

There is an added benefit going forward: new syscalls that need special
handling on x32 can share the same number on x32 and x86_64.  This means
that the special syscall range 512-547 can be treated as a legacy wart
instead of something that may need to be extended in the future.

Also add a selftest to verify the new behavior.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/208024256b764312598f014ebfb0a42472c19354.1562185330.git.luto@kernel.org
2019-07-22 10:31:23 +02:00

54 lines
1.4 KiB
C

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _ASM_X86_UNISTD_H
#define _ASM_X86_UNISTD_H 1
#include <uapi/asm/unistd.h>
# ifdef CONFIG_X86_32
# include <asm/unistd_32.h>
# define __ARCH_WANT_STAT64
# define __ARCH_WANT_SYS_IPC
# define __ARCH_WANT_SYS_OLD_MMAP
# define __ARCH_WANT_SYS_OLD_SELECT
# else
# include <asm/unistd_64.h>
# include <asm/unistd_64_x32.h>
# define __ARCH_WANT_SYS_TIME
# define __ARCH_WANT_SYS_UTIME
# define __ARCH_WANT_COMPAT_SYS_PREADV64
# define __ARCH_WANT_COMPAT_SYS_PWRITEV64
# define __ARCH_WANT_COMPAT_SYS_PREADV64V2
# define __ARCH_WANT_COMPAT_SYS_PWRITEV64V2
# endif
# define __ARCH_WANT_NEW_STAT
# define __ARCH_WANT_OLD_READDIR
# define __ARCH_WANT_OLD_STAT
# define __ARCH_WANT_SYS_ALARM
# define __ARCH_WANT_SYS_FADVISE64
# define __ARCH_WANT_SYS_GETHOSTNAME
# define __ARCH_WANT_SYS_GETPGRP
# define __ARCH_WANT_SYS_NICE
# define __ARCH_WANT_SYS_OLDUMOUNT
# define __ARCH_WANT_SYS_OLD_GETRLIMIT
# define __ARCH_WANT_SYS_OLD_UNAME
# define __ARCH_WANT_SYS_PAUSE
# define __ARCH_WANT_SYS_SIGNAL
# define __ARCH_WANT_SYS_SIGPENDING
# define __ARCH_WANT_SYS_SIGPROCMASK
# define __ARCH_WANT_SYS_SOCKETCALL
# define __ARCH_WANT_SYS_TIME32
# define __ARCH_WANT_SYS_UTIME32
# define __ARCH_WANT_SYS_WAITPID
# define __ARCH_WANT_SYS_FORK
# define __ARCH_WANT_SYS_VFORK
# define __ARCH_WANT_SYS_CLONE
# define __ARCH_WANT_SYS_CLONE3
#endif /* _ASM_X86_UNISTD_H */