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authorRich Felker <dalias@aerifal.cx>2011-05-07 23:23:58 -0400
committerRich Felker <dalias@aerifal.cx>2011-05-07 23:23:58 -0400
commit99b8a25e941e54537bf39ca2f265c345f393f112 (patch)
tree758faba1a20af40b5d09221d008eddbc704636fa /src
parent77f15d108ee021d4dfbeebe793661131c4470d4d (diff)
downloadmusl-99b8a25e941e54537bf39ca2f265c345f393f112.tar.gz
overhaul implementation-internal signal protections
the new approach relies on the fact that the only ways to create sigset_t objects without invoking UB are to use the sig*set() functions, or from the masks returned by sigprocmask, sigaction, etc. or in the ucontext_t argument to a signal handler. thus, as long as sigfillset and sigaddset avoid adding the "protected" signals, there is no way the application will ever obtain a sigset_t including these bits, and thus no need to add the overhead of checking/clearing them when sigprocmask or sigaction is called. note that the old code actually *failed* to remove the bits from sa_mask when sigaction was called. the new implementations are also significantly smaller, simpler, and faster due to ignoring the useless "GNU HURD signals" 65-1024, which are not used and, if there's any sanity in the world, never will be used.
Diffstat (limited to 'src')
-rw-r--r--src/internal/pthread_impl.h9
-rw-r--r--src/signal/raise.c8
-rw-r--r--src/signal/sigaction.c2
-rw-r--r--src/signal/sigaddset.c2
-rw-r--r--src/signal/sigdelset.c2
-rw-r--r--src/signal/sigemptyset.c3
-rw-r--r--src/signal/sigfillset.c8
-rw-r--r--src/signal/sigismember.c2
-rw-r--r--src/signal/sigprocmask.c20
-rw-r--r--src/thread/__rsyscall.c5
-rw-r--r--src/thread/pthread_create.c16
-rw-r--r--src/time/timer_create.c3
12 files changed, 31 insertions, 49 deletions
diff --git a/src/internal/pthread_impl.h b/src/internal/pthread_impl.h
index 049f5dfb..24cbeb25 100644
--- a/src/internal/pthread_impl.h
+++ b/src/internal/pthread_impl.h
@@ -75,9 +75,12 @@ struct __timer {
#include "pthread_arch.h"
-#define SIGCANCEL 32
-#define SIGSYSCALL 33
-#define SIGTIMER 34
+#define SIGTIMER 32
+#define SIGCANCEL 33
+#define SIGSYSCALL 34
+
+#define SIGPT_SET ((sigset_t){{[sizeof(long)==4] = 3<<(32*(sizeof(long)>4))}})
+#define SIGTIMER_SET ((sigset_t){{ 0x80000000 }})
int __set_thread_area(void *);
int __libc_sigaction(int, const struct sigaction *, struct sigaction *);
diff --git a/src/signal/raise.c b/src/signal/raise.c
index 9948f418..71e0505b 100644
--- a/src/signal/raise.c
+++ b/src/signal/raise.c
@@ -1,18 +1,16 @@
#include <signal.h>
#include <errno.h>
+#include <stdint.h>
#include "syscall.h"
-int __sigprocmask(int, const sigset_t *, sigset_t *);
-
int raise(int sig)
{
int pid, tid, ret;
sigset_t set;
- sigfillset(&set);
- __sigprocmask(SIG_BLOCK, &set, &set);
+ __syscall(SYS_rt_sigprocmask, SIG_BLOCK, (uint64_t[]){-1}, &set, 8);
tid = syscall(SYS_gettid);
pid = syscall(SYS_getpid);
ret = syscall(SYS_tgkill, pid, tid, sig);
- __sigprocmask(SIG_SETMASK, &set, 0);
+ __syscall(SYS_rt_sigprocmask, SIG_SETMASK, &set, 0, 8);
return ret;
}
diff --git a/src/signal/sigaction.c b/src/signal/sigaction.c
index 887bbc4f..18956c6b 100644
--- a/src/signal/sigaction.c
+++ b/src/signal/sigaction.c
@@ -35,7 +35,7 @@ int __libc_sigaction(int sig, const struct sigaction *sa, struct sigaction *old)
int __sigaction(int sig, const struct sigaction *sa, struct sigaction *old)
{
- if (sig-SIGCANCEL < 3U) {
+ if (sig-32U < 3) {
errno = EINVAL;
return -1;
}
diff --git a/src/signal/sigaddset.c b/src/signal/sigaddset.c
index 23e655db..d632c6fb 100644
--- a/src/signal/sigaddset.c
+++ b/src/signal/sigaddset.c
@@ -4,7 +4,7 @@
int sigaddset(sigset_t *set, int sig)
{
unsigned s = sig-1;
- if (s >= 8*sizeof(sigset_t)) {
+ if (s >= 8*sizeof(sigset_t) || s-32U<3) {
errno = EINVAL;
return -1;
}
diff --git a/src/signal/sigdelset.c b/src/signal/sigdelset.c
index 14042fb8..f8794ad6 100644
--- a/src/signal/sigdelset.c
+++ b/src/signal/sigdelset.c
@@ -4,7 +4,7 @@
int sigdelset(sigset_t *set, int sig)
{
unsigned s = sig-1;
- if (s >= 8*sizeof(sigset_t)) {
+ if (s >= 8*sizeof(sigset_t) || s-32U<3) {
errno = EINVAL;
return -1;
}
diff --git a/src/signal/sigemptyset.c b/src/signal/sigemptyset.c
index 91f77adf..ca9b8920 100644
--- a/src/signal/sigemptyset.c
+++ b/src/signal/sigemptyset.c
@@ -3,6 +3,7 @@
int sigemptyset(sigset_t *set)
{
- memset(set, 0, sizeof *set);
+ set->__bits[0] = 0;
+ if (sizeof(long)==4) set->__bits[1] = 0;
return 0;
}
diff --git a/src/signal/sigfillset.c b/src/signal/sigfillset.c
index fab50a52..6c84b9b7 100644
--- a/src/signal/sigfillset.c
+++ b/src/signal/sigfillset.c
@@ -1,8 +1,14 @@
#include <signal.h>
#include <string.h>
+#include <limits.h>
int sigfillset(sigset_t *set)
{
- memset(set, -1, sizeof *set);
+#if ULONG_MAX == 0xffffffff
+ set->__bits[0] = 0x7ffffffful;
+ set->__bits[1] = 0xfffffffcul;
+#else
+ set->__bits[0] = 0xfffffffc7ffffffful;
+#endif
return 0;
}
diff --git a/src/signal/sigismember.c b/src/signal/sigismember.c
index afd29e52..d3de6efb 100644
--- a/src/signal/sigismember.c
+++ b/src/signal/sigismember.c
@@ -4,7 +4,7 @@
int sigismember(const sigset_t *set, int sig)
{
unsigned s = sig-1;
- if (s >= 8*sizeof(sigset_t)) {
+ if (s >= 8*sizeof(sigset_t) || s-32U<3) {
errno = EINVAL;
return -1;
}
diff --git a/src/signal/sigprocmask.c b/src/signal/sigprocmask.c
index a272c10d..3f003afb 100644
--- a/src/signal/sigprocmask.c
+++ b/src/signal/sigprocmask.c
@@ -4,27 +4,11 @@
#include "libc.h"
#include "pthread_impl.h"
-int __libc_sigprocmask(int how, const sigset_t *set, sigset_t *old)
+int sigprocmask(int how, const sigset_t *set, sigset_t *old)
{
- return syscall(SYS_rt_sigprocmask, how, set, old, 8);
-}
-
-int __sigprocmask(int how, const sigset_t *set, sigset_t *old)
-{
- sigset_t tmp;
if (how > 2U) {
errno = EINVAL;
return -1;
}
- /* Disallow blocking thread control signals */
- if (set && how != SIG_UNBLOCK) {
- tmp = *set;
- set = &tmp;
- sigdelset(&tmp, SIGCANCEL);
- sigdelset(&tmp, SIGSYSCALL);
- sigdelset(&tmp, SIGTIMER);
- }
- return __libc_sigprocmask(how, set, old);
+ return syscall(SYS_rt_sigprocmask, how, set, old, 8);
}
-
-weak_alias(__sigprocmask, sigprocmask);
diff --git a/src/thread/__rsyscall.c b/src/thread/__rsyscall.c
index 61d41df7..e885d9e7 100644
--- a/src/thread/__rsyscall.c
+++ b/src/thread/__rsyscall.c
@@ -56,8 +56,7 @@ int __rsyscall(int nr, long a, long b, long c, long d, long e, long f)
while ((i=rs.blocks))
__wait(&rs.blocks, 0, i, 1);
- sigfillset(&set);
- __libc_sigprocmask(SIG_BLOCK, &set, &set);
+ __syscall(SYS_rt_sigprocmask, SIG_BLOCK, (uint64_t[]){-1}, &set, 8);
if (!rs.init) {
struct sigaction sa = {
@@ -88,7 +87,7 @@ int __rsyscall(int nr, long a, long b, long c, long d, long e, long f)
}
/* Handle any lingering signals with no-op */
- __libc_sigprocmask(SIG_UNBLOCK, &set, &set);
+ __syscall(SYS_rt_sigprocmask, SIG_SETMASK, &set, &set, 8);
/* Resume other threads' signal handlers and wait for them */
rs.hold = 0;
diff --git a/src/thread/pthread_create.c b/src/thread/pthread_create.c
index 0d2c17bb..6545539b 100644
--- a/src/thread/pthread_create.c
+++ b/src/thread/pthread_create.c
@@ -34,7 +34,7 @@ void __pthread_unwind_next(struct __ptcb *cb)
if (!n) exit(0);
if (self->detached && self->map_base) {
- __syscall(SYS_rt_sigprocmask, SIG_BLOCK, (long)(uint64_t[1]){-1},0,8);
+ __syscall(SYS_rt_sigprocmask, SIG_BLOCK, (uint64_t[]){-1},0,8);
__unmapself(self->map_base, self->map_size);
}
@@ -44,12 +44,8 @@ void __pthread_unwind_next(struct __ptcb *cb)
static int start(void *p)
{
struct pthread *self = p;
- if (self->unblock_cancel) {
- sigset_t set;
- sigemptyset(&set);
- sigaddset(&set, SIGCANCEL);
- __libc_sigprocmask(SIG_UNBLOCK, &set, 0);
- }
+ if (self->unblock_cancel)
+ __syscall(SYS_rt_sigprocmask, SIG_UNBLOCK, &SIGPT_SET, 0, 8);
pthread_exit(self->start(self->start_arg));
return 0;
}
@@ -72,11 +68,7 @@ int pthread_create(pthread_t *res, const pthread_attr_t *attr, void *(*entry)(vo
if (!self) return ENOSYS;
if (!libc.threaded) {
- sigset_t set;
- sigemptyset(&set);
- sigaddset(&set, SIGSYSCALL);
- sigaddset(&set, SIGCANCEL);
- __libc_sigprocmask(SIG_UNBLOCK, &set, 0);
+ __syscall(SYS_rt_sigprocmask, SIG_UNBLOCK, &SIGPT_SET, 0, 8);
libc.threaded = 1;
}
diff --git a/src/time/timer_create.c b/src/time/timer_create.c
index cc10bef0..3bcfa951 100644
--- a/src/time/timer_create.c
+++ b/src/time/timer_create.c
@@ -51,8 +51,7 @@ static void install_handler()
.sa_flags = SA_SIGINFO | SA_RESTART
};
__libc_sigaction(SIGTIMER, &sa, 0);
- sigaddset(&sa.sa_mask, SIGTIMER);
- __libc_sigprocmask(SIG_UNBLOCK, &sa.sa_mask, 0);
+ __syscall(SYS_rt_sigprocmask, SIG_UNBLOCK, &SIGTIMER_SET, 0, 8);
}
static void *start(void *arg)