glibc/sysdeps/unix/sysv/linux/personality.c

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Fix linux personality syscall wrapper The personality system call, starting with linux kernel commit v2.6.29-6609-g11d06b2a1e5658f448a308aa3beb97bacd64a940, always successfully changes the personality if requested. The syscall wrapper, however, still can return an error in the following cases: - the value returned by the system call looks like an error due to architecture limitations of 32-bit kernels; - a personality greater than 0xffffffff is passed to the system call, and the 64-bit kernel does not have commit v2.6.35-rc1-372-g485d527686850d68a0e9006dd9904f19f122485e that would truncate this value to unsigned int; - on sparc64, the value returned by the system call looks like an error due to sparc64 kernel sign extension bug. The solution is three-fold: - move generic syscalls.list personality entry to generic 64-bit syscalls.list file; - for each 32-bit architecture that use negated errno semantics, add a NOERRNO personality entry to their syscalls.list file; - for sparc64 and 32-bit architectures that use dedicated registers to flag syscall errors, add a wrapper around personality syscall; if the system call return value is flagged as an error, this wrapper returns the negated "would be errno" value, otherwise it returns the system call return value; on sparc64, it also truncates the personality argument to unsigned int before passing it to the kernel. [BZ #19408] * sysdeps/unix/sysv/linux/personality.c: New file. * sysdeps/unix/sysv/linux/sparc/sparc64/personality.c: Likewise. * sysdeps/unix/sysv/linux/tst-personality.c: Likewise. * sysdeps/unix/sysv/linux/Makefile [$(subdir) == misc] (sysdep_routines): Add personality. (tests): Add tst-personality. * sysdeps/unix/sysv/linux/syscalls.list (personality): Move ... * sysdeps/unix/sysv/linux/wordsize-64/syscalls.list: ... here. * sysdeps/unix/sysv/linux/arm/syscalls.list (personality): New entry. * sysdeps/unix/sysv/linux/hppa/syscalls.list (personality): Likewise. * sysdeps/unix/sysv/linux/i386/syscalls.list (personality): Likewise. * sysdeps/unix/sysv/linux/m68k/syscalls.list (personality): Likewise. * sysdeps/unix/sysv/linux/microblaze/syscalls.list (personality): Likewise. * sysdeps/unix/sysv/linux/mips/mips64/n32/syscalls.list (personality): Likewise. * sysdeps/unix/sysv/linux/s390/s390-32/syscalls.list (personality): Likewise. * sysdeps/unix/sysv/linux/sh/syscalls.list (personality): Likewise. * sysdeps/unix/sysv/linux/x86_64/x32/syscalls.list (personality): Likewise.
2015-12-27 16:30:02 +00:00
/* Copyright (C) 2015 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#include <sys/personality.h>
#include <sysdep.h>
extern __typeof (personality) __personality;
int
__personality (unsigned long persona)
{
#ifdef PERSONALITY_TRUNCATE_ARGUMENT
/* Starting with kernel commit v2.6.21-3117-g97dc32c, the type of
task_struct->pesonality is "unsigned int".
Starting with kernel commit v2.6.35-rc1-372-g485d527, the personality
syscall accepts "unsigned int" instead of "long unsigned int".
Inbetween, a personality argument that does not fit into "unsigned int"
would result to system call returning -EINVAL.
We explicitly truncate the personality argument to "unsigned int"
to eliminate the uncertainty. */
persona = (unsigned int) persona;
#endif
INTERNAL_SYSCALL_DECL (err);
long ret = INTERNAL_SYSCALL (personality, err, 1, persona);
/* Starting with kernel commit v2.6.29-6609-g11d06b2, the personality syscall
never fails. However, 32-bit kernels might flag valid values as errors, so
we need to reverse the error setting. We can't use the raw result as some
arches split the return/error values. */
if (__glibc_unlikely (INTERNAL_SYSCALL_ERROR_P (ret, err)))
ret = -INTERNAL_SYSCALL_ERRNO (ret, err);
return ret;
}
weak_alias (__personality, personality)