2016-01-04 16:05:18 +00:00
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/* Copyright (C) 2015-2016 Free Software Foundation, Inc.
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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
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#include <sys/personality.h>
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#include <sysdep.h>
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extern __typeof (personality) __personality;
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int
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__personality (unsigned long persona)
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{
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#ifdef PERSONALITY_TRUNCATE_ARGUMENT
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/* Starting with kernel commit v2.6.21-3117-g97dc32c, the type of
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task_struct->pesonality is "unsigned int".
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Starting with kernel commit v2.6.35-rc1-372-g485d527, the personality
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syscall accepts "unsigned int" instead of "long unsigned int".
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Inbetween, a personality argument that does not fit into "unsigned int"
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would result to system call returning -EINVAL.
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We explicitly truncate the personality argument to "unsigned int"
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to eliminate the uncertainty. */
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persona = (unsigned int) persona;
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#endif
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INTERNAL_SYSCALL_DECL (err);
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long ret = INTERNAL_SYSCALL (personality, err, 1, persona);
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/* Starting with kernel commit v2.6.29-6609-g11d06b2, the personality syscall
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never fails. However, 32-bit kernels might flag valid values as errors, so
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we need to reverse the error setting. We can't use the raw result as some
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arches split the return/error values. */
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if (__glibc_unlikely (INTERNAL_SYSCALL_ERROR_P (ret, err)))
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ret = -INTERNAL_SYSCALL_ERRNO (ret, err);
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return ret;
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}
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weak_alias (__personality, personality)
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