From: Rich Felker Date: Sun, 8 May 2011 03:23:58 +0000 (-0400) Subject: overhaul implementation-internal signal protections X-Git-Url: http://nsz.repo.hu/git/?p=musl;a=commitdiff_plain;h=99b8a25e941e54537bf39ca2f265c345f393f112 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. --- diff --git a/dist/config.mak b/dist/config.mak index 691e3ce1..66aa44cd 100644 --- a/dist/config.mak +++ b/dist/config.mak @@ -18,7 +18,7 @@ exec_prefix = /usr/local #CFLAGS += -fomit-frame-pointer -mno-accumulate-outgoing-args # Uncomment for warnings (as errors). Might need tuning to your gcc version. -#CFLAGS += -Werror -Wall -Wpointer-arith -Wcast-align -Wno-parentheses -Wno-char-subscripts -Wno-uninitialized -Wno-sequence-point -Wno-missing-braces -Wno-unused-value +#CFLAGS += -Werror -Wall -Wpointer-arith -Wcast-align -Wno-parentheses -Wno-char-subscripts -Wno-uninitialized -Wno-sequence-point -Wno-missing-braces -Wno-unused-value -Wno-overflow -Wno-int-to-pointer-cast # Uncomment if you want to build a shared library (experimental). #LIBC_LIBS += lib/libc.so 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 #include +#include #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 #include +#include 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)