From d2dc5467c67bc8625a4fc8f285b6a5443bf43df4 Mon Sep 17 00:00:00 2001 From: Adhemerval Zanella Date: Tue, 31 Oct 2017 23:10:37 -0200 Subject: Filter out NPTL internal signals (BZ #22391) 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 --- sysdeps/generic/internal-signals.h | 36 ++++++++++++++++++++++++++++++++++++ 1 file changed, 36 insertions(+) (limited to 'sysdeps/generic/internal-signals.h') diff --git a/sysdeps/generic/internal-signals.h b/sysdeps/generic/internal-signals.h index 01e5b75b6b..17ed48c5bf 100644 --- a/sysdeps/generic/internal-signals.h +++ b/sysdeps/generic/internal-signals.h @@ -15,3 +15,39 @@ You should have received a copy of the GNU Lesser General Public License along with the GNU C Library; if not, see . */ + +#ifndef __INTERNAL_SIGNALS_H +# define __INTERNAL_SIGNALS_H + +static inline bool +__is_internal_signal (int sig) +{ + return false; +} + +static inline void +__clear_internal_signals (sigset_t *set) +{ +} + +static inline int +__libc_signal_block_all (sigset_t *set) +{ + return 0; +} + +static inline int +__libc_signal_block_app (sigset_t *set) +{ + return 0; +} + +/* Restore current process signal mask. */ +static inline int +__libc_signal_restore_set (const sigset_t *set) +{ + return 0; +} + + +#endif /* __INTERNAL_SIGNALS_H */ -- cgit v1.2.3