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[PATCH v3 3/3] Filter out NPTL internal signals (BZ #22391)
- From: Adhemerval Zanella <adhemerval dot zanella at linaro dot org>
- To: libc-alpha at sourceware dot org
- Date: Wed, 15 Nov 2017 15:54:11 -0200
- Subject: [PATCH v3 3/3] Filter out NPTL internal signals (BZ #22391)
- Authentication-results: sourceware.org; auth=none
- References: <1510768451-18453-1-git-send-email-adhemerval.zanella@linaro.org>
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.
* 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/nptl/nptl-signals.h (__clear_internal_signals,
__is_internal_signal): New functions.
* sysdeps/nptl/sigfillset.c: Remove file.
* sysdeps/unix/sysv/linux/nptl-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.
* sysdeps/unix/sysv/linux/sigwait.c (do_sigtwait): Likewise.
Signed-off-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Reported-by: Yury Norov <ynorov@caviumnetworks.com>
---
ChangeLog | 25 ++++++++
nptl/sigaction.c | 14 +----
signal/sigaction.c | 2 +-
signal/sigaddset.c | 5 +-
signal/sigdelset.c | 5 +-
signal/sigfillset.c | 10 +---
signal/tst-sigset.c | 92 ++++++++++++++++++++++--------
sysdeps/generic/internal-signals.h | 11 ++++
sysdeps/nptl/sigfillset.c | 20 -------
sysdeps/posix/signal.c | 5 +-
sysdeps/posix/sigset.c | 10 +---
sysdeps/unix/sysv/linux/internal-signals.h | 4 +-
sysdeps/unix/sysv/linux/sigtimedwait.c | 17 +-----
13 files changed, 124 insertions(+), 96 deletions(-)
delete mode 100644 sysdeps/nptl/sigfillset.c
diff --git a/nptl/sigaction.c b/nptl/sigaction.c
index 2994fd5..b2ff674 100644
--- a/nptl/sigaction.c
+++ b/nptl/sigaction.c
@@ -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;
diff --git a/signal/sigaction.c b/signal/sigaction.c
index 8a6220c..3025aab 100644
--- a/signal/sigaction.c
+++ b/signal/sigaction.c
@@ -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;
diff --git a/signal/sigaddset.c b/signal/sigaddset.c
index 161be7b..a435f61 100644
--- a/signal/sigaddset.c
+++ b/signal/sigaddset.c
@@ -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;
diff --git a/signal/sigdelset.c b/signal/sigdelset.c
index 2aaa536..01a50ec 100644
--- a/signal/sigdelset.c
+++ b/signal/sigdelset.c
@@ -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;
diff --git a/signal/sigfillset.c b/signal/sigfillset.c
index 0fcc24a..560c66e 100644
--- a/signal/sigfillset.c
+++ b/signal/sigfillset.c
@@ -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;
}
diff --git a/signal/tst-sigset.c b/signal/tst-sigset.c
index d47adcc..a2b764d 100644
--- a/signal/tst-sigset.c
+++ b/signal/tst-sigset.c
@@ -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;
+ sigset_t set;
+ TEST_VERIFY (sigemptyset (&set) == 0);
-#define TRY(call) \
- if (call) \
- { \
- printf ("%s (sig = %d): %m\n", #call, sig); \
- result = 1; \
- } \
- else
+#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);
- sigset_t set;
- TRY (sigemptyset (&set) != 0);
+ /* 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);
-#ifdef SIGRTMAX
- int max_sig = SIGRTMAX;
-#else
- int max_sig = NSIG - 1;
+ /* 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>
diff --git a/sysdeps/generic/internal-signals.h b/sysdeps/generic/internal-signals.h
index 55bc07d..8a8854c 100644
--- a/sysdeps/generic/internal-signals.h
+++ b/sysdeps/generic/internal-signals.h
@@ -15,3 +15,14 @@
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/>. */
+
+static inline void
+__clear_internal_signals (sigset_t *set)
+{
+}
+
+static inline bool
+__is_internal_signal (int sig)
+{
+ return false;
+}
diff --git a/sysdeps/nptl/sigfillset.c b/sysdeps/nptl/sigfillset.c
deleted file mode 100644
index 50e8512..0000000
--- a/sysdeps/nptl/sigfillset.c
+++ /dev/null
@@ -1,20 +0,0 @@
-/* Copyright (C) 2003-2017 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>
diff --git a/sysdeps/posix/signal.c b/sysdeps/posix/signal.c
index 81ba177..87c5d1c 100644
--- a/sysdeps/posix/signal.c
+++ b/sysdeps/posix/signal.c
@@ -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;
diff --git a/sysdeps/posix/sigset.c b/sysdeps/posix/sigset.c
index a4dfe0a..6234ecf 100644
--- a/sysdeps/posix/sigset.c
+++ b/sysdeps/posix/sigset.c
@@ -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)
{
diff --git a/sysdeps/unix/sysv/linux/internal-signals.h b/sysdeps/unix/sysv/linux/internal-signals.h
index bb8234d..bf33bbc 100644
--- a/sysdeps/unix/sysv/linux/internal-signals.h
+++ b/sysdeps/unix/sysv/linux/internal-signals.h
@@ -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
@@ -43,7 +45,7 @@ __has_internal_signal (const sigset_t *set)
}
/* Return is sig is used internally. */
-static inline int
+static inline bool
__is_internal_signal (int sig)
{
return (sig == SIGCANCEL) || (sig == SIGSETXID);
diff --git a/sysdeps/unix/sysv/linux/sigtimedwait.c b/sysdeps/unix/sysv/linux/sigtimedwait.c
index 2d96dd4..b4977e3 100644
--- a/sysdeps/unix/sysv/linux/sigtimedwait.c
+++ b/sysdeps/unix/sysv/linux/sigtimedwait.c
@@ -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
--
2.7.4