From 37e31f79514acfdff8ede65b73542b7abb1e61a5 Mon Sep 17 00:00:00 2001 From: Laurent Bercot Date: Wed, 26 Feb 2020 17:18:47 +0000 Subject: Explicitly unblock signals when selfpiped without signalfd This is arguably a bugfix, since selfpipe without signalfd relies on signals being actually delivered, and a process may have inherited a nonempty sigprocmask. Also use SIG_BLOCK instead of SIG_SETMASK when using selfpipe_trapset() with signalfd, because we shouldn't unblock signals that may have previously been blocked. This is also arguably a bugfix. This commit is essential for using the version of s6-linux-init that blocks SIGINT before disablecad on kernels without signalfd. Without it, SIGINT never gets unblocked, so it's never delivered to s6-svscan. --- src/libstddjb/selfpipe_trap.c | 2 +- src/libstddjb/selfpipe_trapset.c | 4 ++-- 2 files changed, 3 insertions(+), 3 deletions(-) diff --git a/src/libstddjb/selfpipe_trap.c b/src/libstddjb/selfpipe_trap.c index f07db64..090d5ac 100644 --- a/src/libstddjb/selfpipe_trap.c +++ b/src/libstddjb/selfpipe_trap.c @@ -38,7 +38,7 @@ int selfpipe_trap (int sig) { if (selfpipe_fd < 0) return (errno = EBADF, -1) ; if (sig_catcha(sig, &selfpipe_ssa) < 0) return -1 ; - if (sigaddset(&selfpipe_caught, sig) < 0) + if (sigprocmask(SIG_UNBLOCK, sig, 0) < 0 || sigaddset(&selfpipe_caught, sig) < 0) { int e = errno ; sig_restore(sig) ; diff --git a/src/libstddjb/selfpipe_trapset.c b/src/libstddjb/selfpipe_trapset.c index ad5ba10..542ad10 100644 --- a/src/libstddjb/selfpipe_trapset.c +++ b/src/libstddjb/selfpipe_trapset.c @@ -14,7 +14,7 @@ int selfpipe_trapset (sigset_t const *set) { sigset_t old ; if (selfpipe_fd < 0) return (errno = EBADF, -1) ; - if (sigprocmask(SIG_SETMASK, set, &old) < 0) return -1 ; + if (sigprocmask(SIG_BLOCK, set, &old) < 0) return -1 ; if (signalfd(selfpipe_fd, set, SFD_NONBLOCK | SFD_CLOEXEC) < 0) { int e = errno ; @@ -53,7 +53,7 @@ int selfpipe_trapset (sigset_t const *set) if (sig_restore(i) < 0) break ; } } - if (i < SKALIBS_NSIG) + if (i < SKALIBS_NSIG || sigprocmask(SIG_UNBLOCK, set, 0) < 0) { int e = errno ; sig_restoreto(set, i) ; -- cgit v1.2.3