Fix for https://bugs.php.net/74083 master PHP-fpm is stopped on multiple reloads
backported for 7.4 from
From ae5154c6c6af7ba7c592f8af006b7cadd0d66d6e Mon Sep 17 00:00:00 2001
From: Maksim Nikulin <mnikulin@plesk.com>
Date: Wed, 24 Jul 2019 16:50:57 +0700
Subject: [PATCH] Block signals during fpm master initialization
From e37bd5dcc2e8f269c6031d86429311c8cf243060 Mon Sep 17 00:00:00 2001
From: Maksim Nikulin <mnikulin@plesk.com>
Date: Mon, 21 Oct 2019 14:23:29 +0700
Subject: [PATCH] Do not let PHP-FPM children miss SIGTERM, SIGQUIT
diff -up ./sapi/fpm/fpm/fpm_children.c.fpmsig ./sapi/fpm/fpm/fpm_children.c
--- ./sapi/fpm/fpm/fpm_children.c.fpmsig 2020-10-23 10:36:31.423925856 +0200
+++ ./sapi/fpm/fpm/fpm_children.c 2020-10-23 10:36:38.872900642 +0200
@@ -404,6 +404,11 @@ int fpm_children_make(struct fpm_worker_
return 2;
}
+ zlog(ZLOG_DEBUG, "blocking signals before child birth");
+ if (0 > fpm_signals_child_block()) {
+ zlog(ZLOG_WARNING, "child may miss signals");
+ }
+
pid = fork();
switch (pid) {
@@ -415,12 +420,16 @@ int fpm_children_make(struct fpm_worker_
return 0;
case -1 :
+ zlog(ZLOG_DEBUG, "unblocking signals");
+ fpm_signals_unblock();
zlog(ZLOG_SYSERROR, "fork() failed");
fpm_resources_discard(child);
return 2;
default :
+ zlog(ZLOG_DEBUG, "unblocking signals, child born");
+ fpm_signals_unblock();
child->pid = pid;
fpm_clock_get(&child->started);
fpm_parent_resources_use(child);
diff -up ./sapi/fpm/fpm/fpm_main.c.fpmsig ./sapi/fpm/fpm/fpm_main.c
--- ./sapi/fpm/fpm/fpm_main.c.fpmsig 2020-10-13 11:27:02.000000000 +0200
+++ ./sapi/fpm/fpm/fpm_main.c 2020-10-23 10:36:38.873900639 +0200
@@ -90,6 +90,7 @@ int __riscosify_control = __RISCOSIFY_ST
#include "fpm.h"
#include "fpm_request.h"
#include "fpm_status.h"
+#include "fpm_signals.h"
#include "fpm_conf.h"
#include "fpm_php.h"
#include "fpm_log.h"
@@ -1584,6 +1585,11 @@ int main(int argc, char *argv[])
closes it. in apache|apxs mode apache
does that for us! thies@thieso.net
20000419 */
+
+ if (0 > fpm_signals_init_mask() || 0 > fpm_signals_block()) {
+ zlog(ZLOG_WARNING, "Could die in the case of too early reload signal");
+ }
+ zlog(ZLOG_DEBUG, "Blocked some signals");
#endif
#endif
diff -up ./sapi/fpm/fpm/fpm_process_ctl.c.fpmsig ./sapi/fpm/fpm/fpm_process_ctl.c
--- ./sapi/fpm/fpm/fpm_process_ctl.c.fpmsig 2020-10-13 11:27:02.000000000 +0200
+++ ./sapi/fpm/fpm/fpm_process_ctl.c 2020-10-23 10:36:11.921991864 +0200
@@ -77,6 +77,10 @@ static void fpm_pctl_exit() /* {{{ */
static void fpm_pctl_exec() /* {{{ */
{
+ zlog(ZLOG_DEBUG, "Blocking some signals before reexec");
+ if (0 > fpm_signals_block()) {
+ zlog(ZLOG_WARNING, "concurrent reloads may be unstable");
+ }
zlog(ZLOG_NOTICE, "reloading: execvp(\"%s\", {\"%s\""
"%s%s%s" "%s%s%s" "%s%s%s" "%s%s%s" "%s%s%s"
diff -up ./sapi/fpm/fpm/fpm_signals.c.fpmsig ./sapi/fpm/fpm/fpm_signals.c
--- ./sapi/fpm/fpm/fpm_signals.c.fpmsig 2020-10-13 11:27:02.000000000 +0200
+++ ./sapi/fpm/fpm/fpm_signals.c 2020-10-23 10:36:38.873900639 +0200
@@ -19,6 +19,8 @@
#include "zlog.h"
static int sp[2];
+static sigset_t block_sigset;
+static sigset_t child_block_sigset;
const char *fpm_signal_names[NSIG + 1] = {
#ifdef SIGHUP
@@ -165,8 +167,11 @@ static void sig_handler(int signo) /* {{
int saved_errno;
if (fpm_globals.parent_pid != getpid()) {
- /* prevent a signal race condition when child process
- have not set up it's own signal handler yet */
+ /* Avoid using of signal handlers from the master process in a worker
+ before the child sets up its own signal handlers.
+ Normally it is prevented by the sigprocmask() calls
+ around fork(). This execution branch is a last resort trap
+ that has no protection against #76601. */
return;
}
@@ -210,6 +215,11 @@ int fpm_signals_init_main() /* {{{ */
zlog(ZLOG_SYSERROR, "failed to init signals: sigaction()");
return -1;
}
+
+ zlog(ZLOG_DEBUG, "Unblocking all signals");
+ if (0 > fpm_signals_unblock()) {
+ return -1;
+ }
return 0;
}
/* }}} */
@@ -241,6 +251,10 @@ int fpm_signals_init_child() /* {{{ */
}
zend_signal_init();
+
+ if (0 > fpm_signals_unblock()) {
+ return -1;
+ }
return 0;
}
/* }}} */
@@ -250,3 +264,72 @@ int fpm_signals_get_fd() /* {{{ */
return sp[0];
}
/* }}} */
+
+int fpm_signals_init_mask() /* {{{ */
+{
+ /* Subset of signals from fpm_signals_init_main() and fpm_got_signal()
+ blocked to avoid unexpected death during early init
+ or during reload just after execvp() or fork */
+ int init_signal_array[] = { SIGUSR1, SIGUSR2, SIGCHLD };
+ size_t size = sizeof(init_signal_array)/sizeof(init_signal_array[0]);
+ size_t i = 0;
+ if (0 > sigemptyset(&block_sigset) ||
+ 0 > sigemptyset(&child_block_sigset)) {
+ zlog(ZLOG_SYSERROR, "failed to prepare signal block mask: sigemptyset()");
+ return -1;
+ }
+ for (i = 0; i < size; ++i) {
+ int sig_i = init_signal_array[i];
+ if (0 > sigaddset(&block_sigset, sig_i) ||
+ 0 > sigaddset(&child_block_sigset, sig_i)) {
+ if (sig_i <= NSIG && fpm_signal_names[sig_i] != NULL) {
+ zlog(ZLOG_SYSERROR, "failed to prepare signal block mask: sigaddset(%s)",
+ fpm_signal_names[sig_i]);
+ } else {
+ zlog(ZLOG_SYSERROR, "failed to prepare signal block mask: sigaddset(%d)", sig_i);
+ }
+ return -1;
+ }
+ }
+ if (0 > sigaddset(&child_block_sigset, SIGTERM) ||
+ 0 > sigaddset(&child_block_sigset, SIGQUIT)) {
+ zlog(ZLOG_SYSERROR, "failed to prepare child signal block mask: sigaddset()");
+ return -1;
+ }
+ return 0;
+}
+/* }}} */
+
+int fpm_signals_block() /* {{{ */
+{
+ if (0 > sigprocmask(SIG_BLOCK, &block_sigset, NULL)) {
+ zlog(ZLOG_SYSERROR, "failed to block signals");
+ return -1;
+ }
+ return 0;
+}
+/* }}} */
+
+int fpm_signals_child_block() /* {{{ */
+{
+ if (0 > sigprocmask(SIG_BLOCK, &child_block_sigset, NULL)) {
+ zlog(ZLOG_SYSERROR, "failed to block child signals");
+ return -1;
+ }
+ return 0;
+}
+/* }}} */
+
+int fpm_signals_unblock() /* {{{ */
+{
+ /* Ensure that during reload after upgrade all signals are unblocked.
+ block_sigset could have different value before execve() */
+ sigset_t all_signals;
+ sigfillset(&all_signals);
+ if (0 > sigprocmask(SIG_UNBLOCK, &all_signals, NULL)) {
+ zlog(ZLOG_SYSERROR, "failed to unblock signals");
+ return -1;
+ }
+ return 0;
+}
+/* }}} */
diff -up ./sapi/fpm/fpm/fpm_signals.h.fpmsig ./sapi/fpm/fpm/fpm_signals.h
--- ./sapi/fpm/fpm/fpm_signals.h.fpmsig 2020-10-13 11:27:02.000000000 +0200
+++ ./sapi/fpm/fpm/fpm_signals.h 2020-10-23 10:36:38.873900639 +0200
@@ -8,6 +8,10 @@
int fpm_signals_init_main();
int fpm_signals_init_child();
int fpm_signals_get_fd();
+int fpm_signals_init_mask();
+int fpm_signals_block();
+int fpm_signals_child_block();
+int fpm_signals_unblock();
extern const char *fpm_signal_names[NSIG + 1];