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Filter out NPTL internal signals (BZ #22391)

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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>
This commit is contained in:
Adhemerval Zanella 2017-10-31 23:10:37 -02:00
parent 511ed56f2e
commit d2dc5467c6
13 changed files with 152 additions and 98 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

26
ChangeLog
View File

@ -1,3 +1,29 @@
2018-04-03 Adhemerval Zanella <adhemerval.zanella@linaro.org>
[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.
2018-04-03 Samuel Thibault <samuel.thibault@ens-lyon.org>
* sysdeps/mach/hurd/if_index.c (__if_nametoindex): Always end

14
nptl/sigaction.c
View File

@ -16,22 +16,12 @@
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
/* This is no complete implementation. The file is meant to be
included in the real implementation to provide the wrapper around
__libc_sigaction. */
#include <nptl/pthreadP.h>
/* We use the libc implementation but we tell it to not allow
SIGCANCEL or SIGTIMER to be handled. */
#define LIBC_SIGACTION 1
#include <internal-signals.h>
int
__sigaction (int sig, const struct sigaction *act, struct sigaction *oact)
{
if (__glibc_unlikely (sig == SIGCANCEL || sig == SIGSETXID))
if (sig <= 0 || sig >= NSIG || __is_internal_signal (sig))
{
__set_errno (EINVAL);
return -1;

2
signal/sigaction.c
View File

@ -24,7 +24,7 @@
int
__sigaction (int sig, const struct sigaction *act, struct sigaction *oact)
{
if (sig <= 0 || sig >= NSIG)
if (sig <= 0 || sig >= NSIG || __is_internal_signal (sig))
{
__set_errno (EINVAL);
return -1;

5
signal/sigaddset.c
View File

@ -17,13 +17,14 @@
#include <errno.h>
#include <signal.h>
#include <sigsetops.h>
#include <internal-signals.h>
/* Add SIGNO to SET. */
int
sigaddset (sigset_t *set, int signo)
{
if (set == NULL || signo <= 0 || signo >= NSIG)
if (set == NULL || signo <= 0 || signo >= NSIG
|| __is_internal_signal (signo))
{
__set_errno (EINVAL);
return -1;

5
signal/sigdelset.c
View File

@ -17,13 +17,14 @@
#include <errno.h>
#include <signal.h>
#include <sigsetops.h>
#include <internal-signals.h>
/* Add SIGNO to SET. */
int
sigdelset (sigset_t *set, int signo)
{
if (set == NULL || signo <= 0 || signo >= NSIG)
if (set == NULL || signo <= 0 || signo >= NSIG
|| __is_internal_signal (signo))
{
__set_errno (EINVAL);
return -1;

10
signal/sigfillset.c
View File

@ -18,6 +18,7 @@
#include <errno.h>
#include <signal.h>
#include <string.h>
#include <internal-signals.h>
/* Set all signals in SET. */
int
@ -31,14 +32,7 @@ sigfillset (sigset_t *set)
memset (set, 0xff, sizeof (sigset_t));
/* If the implementation uses a cancellation signal don't set the bit. */
#ifdef SIGCANCEL
__sigdelset (set, SIGCANCEL);
#endif
/* Likewise for the signal to implement setxid. */
#ifdef SIGSETXID
__sigdelset (set, SIGSETXID);
#endif
__clear_internal_signals (set);
return 0;
}

96
signal/tst-sigset.c
View File

@ -1,43 +1,85 @@
/* Test sig*set functions. */
#include <signal.h>
#include <stdio.h>
#define TEST_FUNCTION do_test ()
#include <support/check.h>
static int
do_test (void)
{
int result = 0;
int sig = -1;
#define TRY(call) \
if (call) \
{ \
printf ("%s (sig = %d): %m\n", #call, sig); \
result = 1; \
} \
else
sigset_t set;
TRY (sigemptyset (&set) != 0);
TEST_VERIFY (sigemptyset (&set) == 0);
#ifdef SIGRTMAX
int max_sig = SIGRTMAX;
#else
int max_sig = NSIG - 1;
#define VERIFY(set, sig) \
TEST_VERIFY (sigismember (&set, sig) == 0); \
TEST_VERIFY (sigaddset (&set, sig) == 0); \
TEST_VERIFY (sigismember (&set, sig) != 0); \
TEST_VERIFY (sigdelset (&set, sig) == 0); \
TEST_VERIFY (sigismember (&set, sig) == 0)
/* ISO C99 signals. */
VERIFY (set, SIGINT);
VERIFY (set, SIGILL);
VERIFY (set, SIGABRT);
VERIFY (set, SIGFPE);
VERIFY (set, SIGSEGV);
VERIFY (set, SIGTERM);
/* Historical signals specified by POSIX. */
VERIFY (set, SIGHUP);
VERIFY (set, SIGQUIT);
VERIFY (set, SIGTRAP);
VERIFY (set, SIGKILL);
VERIFY (set, SIGBUS);
VERIFY (set, SIGSYS);
VERIFY (set, SIGPIPE);
VERIFY (set, SIGALRM);
/* New(er) POSIX signals (1003.1-2008, 1003.1-2013). */
VERIFY (set, SIGURG);
VERIFY (set, SIGSTOP);
VERIFY (set, SIGTSTP);
VERIFY (set, SIGCONT);
VERIFY (set, SIGCHLD);
VERIFY (set, SIGTTIN);
VERIFY (set, SIGTTOU);
VERIFY (set, SIGPOLL);
VERIFY (set, SIGXCPU);
VERIFY (set, SIGXFSZ);
VERIFY (set, SIGVTALRM);
VERIFY (set, SIGPROF);
VERIFY (set, SIGUSR1);
VERIFY (set, SIGUSR2);
/* Nonstandard signals found in all modern POSIX systems
(including both BSD and Linux). */
VERIFY (set, SIGWINCH);
/* Arch-specific signals. */
#ifdef SIGEMT
VERIFY (set, SIGEMT);
#endif
#ifdef SIGLOST
VERIFY (set, SIGLOST);
#endif
#ifdef SIGINFO
VERIFY (set, SIGINFO);
#endif
#ifdef SIGSTKFLT
VERIFY (set, SIGSTKFLT);
#endif
#ifdef SIGPWR
VERIFY (set, SIGPWR);
#endif
for (sig = 1; sig <= max_sig; ++sig)
/* Read-time signals (POSIX.1b real-time extensions). If they are
supported SIGRTMAX value is greater than SIGRTMIN. */
for (int rtsig = SIGRTMIN; rtsig <= SIGRTMAX; rtsig++)
{
TRY (sigismember (&set, sig) != 0);
TRY (sigaddset (&set, sig) != 0);
TRY (sigismember (&set, sig) == 0);
TRY (sigdelset (&set, sig) != 0);
TRY (sigismember (&set, sig) != 0);
VERIFY (set, rtsig);
}
return result;
return 0;
}
#include "../test-skeleton.c"
#include <support/test-driver.c>

36
sysdeps/generic/internal-signals.h
View File

@ -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
<http://www.gnu.org/licenses/>. */
#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 */

20
sysdeps/nptl/sigfillset.c
View File

@ -1,20 +0,0 @@
/* Copyright (C) 2003-2018 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 <nptl/pthreadP.h>
#include <signal/sigfillset.c>

5
sysdeps/posix/signal.c
View File

@ -18,8 +18,8 @@
#include <errno.h>
#include <signal.h>
#include <string.h> /* For the real memset prototype. */
#include <sigsetops.h>
#include <internal-signals.h>
sigset_t _sigintr attribute_hidden; /* Set by siginterrupt. */
@ -31,7 +31,8 @@ __bsd_signal (int sig, __sighandler_t handler)
struct sigaction act, oact;
/* Check signal extents to protect __sigismember. */
if (handler == SIG_ERR || sig < 1 || sig >= NSIG)
if (handler == SIG_ERR || sig < 1 || sig >= NSIG
|| __is_internal_signal (sig))
{
__set_errno (EINVAL);
return SIG_ERR;

10
sysdeps/posix/sigset.c
View File

@ -31,15 +31,9 @@ sigset (int sig, __sighandler_t disp)
sigset_t set;
sigset_t oset;
/* Check signal extents to protect __sigismember. */
if (disp == SIG_ERR || sig < 1 || sig >= NSIG)
{
__set_errno (EINVAL);
return SIG_ERR;
}
__sigemptyset (&set);
__sigaddset (&set, sig);
if (sigaddset (&set, sig) < 0)
return SIG_ERR;
if (disp == SIG_HOLD)
{

4
sysdeps/unix/sysv/linux/internal-signals.h
View File

@ -21,6 +21,8 @@
#include <signal.h>
#include <sigsetops.h>
#include <stdbool.h>
#include <sysdep.h>
/* The signal used for asynchronous cancelation. */
#define SIGCANCEL __SIGRTMIN
@ -37,7 +39,7 @@
/* Return is sig is used internally. */
static inline int
static inline bool
__is_internal_signal (int sig)
{
return (sig == SIGCANCEL) || (sig == SIGSETXID);

17
sysdeps/unix/sysv/linux/sigtimedwait.c
View File

@ -24,21 +24,8 @@ int
__sigtimedwait (const sigset_t *set, siginfo_t *info,
const struct timespec *timeout)
{
sigset_t tmpset;
if (set != NULL
&& (__builtin_expect (__sigismember (set, SIGCANCEL), 0)
|| __builtin_expect (__sigismember (set, SIGSETXID), 0)))
{
/* Create a temporary mask without the bit for SIGCANCEL set. */
// We are not copying more than we have to.
memcpy (&tmpset, set, _NSIG / 8);
__sigdelset (&tmpset, SIGCANCEL);
__sigdelset (&tmpset, SIGSETXID);
set = &tmpset;
}
/* XXX The size argument hopefully will have to be changed to the
real size of the user-level sigset_t. */
/* XXX The size argument hopefully will have to be changed to the
real size of the user-level sigset_t. */
int result = SYSCALL_CANCEL (rt_sigtimedwait, set, info, timeout, _NSIG / 8);
/* The kernel generates a SI_TKILL code in si_code in case tkill is