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d2dc5467c6
This patch filters out the internal NPTL signals (SIGCANCEL/SIGTIMER and
SIGSETXID) from signal functions. GLIBC on Linux requires both signals to
proper implement pthread cancellation, posix timers, and set*id posix
thread synchronization.
And not filtering out the internal signal is troublesome:
- A conformant program on a architecture that does not filter out the
signals might inadvertently disable pthread asynchronous cancellation,
set*id synchronization or posix timers.
- It might also to security issues if SIGSETXID is masked and set*id
functions are called (some threads might have effective user or group
id different from the rest).
The changes are basically:
- Change __is_internal_signal to bool and used on all signal function
that has a signal number as input. Also for signal function which accepts
signals sets (sigset_t) it assumes that canonical function were used to
add/remove signals which lead to some input simplification.
- Fix tst-sigset.c to avoid check for SIGCANCEL/SIGTIMER and SIGSETXID.
It is rewritten to check each signal indidually and to check realtime
signals using canonical macros.
- Add generic __clear_internal_signals and __is_internal_signal
version since both symbols are used on generic implementations.
- Remove superflous sysdeps/nptl/sigfillset.c.
- Remove superflous SIGTIMER handling on Linux __is_internal_signal
since it is the same of SIGCANCEL.
- Remove dangling define and obvious comment on nptl/sigaction.c.
Checked on x86_64-linux-gnu.
[BZ #22391]
* nptl/sigaction.c (__sigaction): Use __is_internal_signal to
check for internal nptl signals.
* nptl/sigaction.c (__sigaction): Likewise.
* signal/sigaddset.c (sigaddset): Likewise.
* signal/sigdelset.c (sigdelset): Likewise.
* sysdeps/posix/signal.c (__bsd_signal): Likewise.
* sysdeps/posix/sigset.c (sigset): Call and check sigaddset return
value.
* signal/sigfillset.c (sigfillset): User __clear_internal_signals
to filter out internal nptl signals.
* signal/tst-sigset.c (do_test): Check ech signal indidually and
also check realtime signals using standard macros.
* sysdeps/generic/internal-signals.h (__clear_internal_signals,
__is_internal_signal, __libc_signal_block_all,
__libc_signal_block_app, __libc_signal_restore_set): New functions.
* sysdeps/nptl/sigfillset.c: Remove file.
* sysdeps/unix/sysv/linux/internal-signals.h (__is_internal_signal):
Change return to bool.
(__clear_internal_signals): Remove SIGTIMER clean since it is
equal to SIGCANEL on Linux.
* sysdeps/unix/sysv/linux/sigtimedwait.c (__sigtimedwait): Assume
signal set was constructed using standard functions.
Reported-by: Yury Norov <ynorov@caviumnetworks.com>
92 lines
2.7 KiB
C
92 lines
2.7 KiB
C
/* Special use of signals internally. Linux version.
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Copyright (C) 2014-2018 Free Software Foundation, Inc.
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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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#ifndef __INTERNAL_SIGNALS_H
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# define __INTERNAL_SIGNALS_H
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#include <signal.h>
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#include <sigsetops.h>
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#include <stdbool.h>
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#include <sysdep.h>
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/* The signal used for asynchronous cancelation. */
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#define SIGCANCEL __SIGRTMIN
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/* Signal needed for the kernel-supported POSIX timer implementation.
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We can reuse the cancellation signal since we can distinguish
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cancellation from timer expirations. */
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#define SIGTIMER SIGCANCEL
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/* Signal used to implement the setuid et.al. functions. */
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#define SIGSETXID (__SIGRTMIN + 1)
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/* Return is sig is used internally. */
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static inline bool
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__is_internal_signal (int sig)
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{
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return (sig == SIGCANCEL) || (sig == SIGSETXID);
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}
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/* Remove internal glibc signal from the mask. */
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static inline void
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__clear_internal_signals (sigset_t *set)
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{
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__sigdelset (set, SIGCANCEL);
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__sigdelset (set, SIGSETXID);
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}
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#define SIGALL_SET \
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((__sigset_t) { .__val = {[0 ... _SIGSET_NWORDS-1 ] = -1 } })
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/* Block all signals, including internal glibc ones. */
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static inline int
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__libc_signal_block_all (sigset_t *set)
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{
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INTERNAL_SYSCALL_DECL (err);
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return INTERNAL_SYSCALL (rt_sigprocmask, err, 4, SIG_BLOCK, &SIGALL_SET,
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set, _NSIG / 8);
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}
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/* Block all application signals (excluding internal glibc ones). */
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static inline int
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__libc_signal_block_app (sigset_t *set)
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{
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sigset_t allset = SIGALL_SET;
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__clear_internal_signals (&allset);
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INTERNAL_SYSCALL_DECL (err);
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return INTERNAL_SYSCALL (rt_sigprocmask, err, 4, SIG_BLOCK, &allset, set,
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_NSIG / 8);
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}
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/* Restore current process signal mask. */
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static inline int
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__libc_signal_restore_set (const sigset_t *set)
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{
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INTERNAL_SYSCALL_DECL (err);
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return INTERNAL_SYSCALL (rt_sigprocmask, err, 4, SIG_SETMASK, set, NULL,
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_NSIG / 8);
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}
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/* Used to communicate with signal handler. */
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extern struct xid_command *__xidcmd attribute_hidden;
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#endif
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