upstream: Replace all calls to signal(2) with a wrapper around

sigaction(2). This wrapper blocks all other signals during the handler
preventing races between handlers, and sets SA_RESTART which should reduce
the potential for short read/write operations.

OpenBSD-Commit-ID: 5e047663fd77a40d7b07bdabe68529df51fd2519

1 files changed, 18 insertions, 16 deletions

diff --git a/sshd.c b/sshd.c
index 46f693a8e..c447edfe1 100644
--- a/sshd.c
+++ b/sshd.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: sshd.c,v 1.543 2020/01/21 22:39:57 djm Exp $ */
+/* $OpenBSD: sshd.c,v 1.544 2020/01/23 07:10:22 dtucker Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -313,7 +313,7 @@ sighup_restart(void)
 	close_listen_socks();
 	close_startup_pipes();
 	alarm(0);  /* alarm timer persists across exec */
-	signal(SIGHUP, SIG_IGN); /* will be restored after exec */
+	ssh_signal(SIGHUP, SIG_IGN); /* will be restored after exec */
 	execv(saved_argv[0], saved_argv);
 	logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
 	    strerror(errno));
@@ -342,6 +342,8 @@ main_sigchld_handler(int sig)
 	pid_t pid;
 	int status;
 
+	debug("main_sigchld_handler: %s", strsignal(sig));
+
 	while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
 	    (pid == -1 && errno == EINTR))
 		;
@@ -363,7 +365,7 @@ grace_alarm_handler(int sig)
 	 * keys command helpers.
 	 */
 	if (getpgid(0) == getpid()) {
-		signal(SIGTERM, SIG_IGN);
+		ssh_signal(SIGTERM, SIG_IGN);
 		kill(0, SIGTERM);
 	}
 
@@ -1941,7 +1943,7 @@ main(int ac, char **av)
 		error("chdir(\"/\"): %s", strerror(errno));
 
 	/* ignore SIGPIPE */
-	signal(SIGPIPE, SIG_IGN);
+	ssh_signal(SIGPIPE, SIG_IGN);
 
 	/* Get a connection, either from inetd or a listening TCP socket */
 	if (inetd_flag) {
@@ -1950,10 +1952,10 @@ main(int ac, char **av)
 		platform_pre_listen();
 		server_listen();
 
-		signal(SIGHUP, sighup_handler);
-		signal(SIGCHLD, main_sigchld_handler);
-		signal(SIGTERM, sigterm_handler);
-		signal(SIGQUIT, sigterm_handler);
+		ssh_signal(SIGHUP, sighup_handler);
+		ssh_signal(SIGCHLD, main_sigchld_handler);
+		ssh_signal(SIGTERM, sigterm_handler);
+		ssh_signal(SIGQUIT, sigterm_handler);
 
 		/*
 		 * Write out the pid file after the sigterm handler
@@ -2043,12 +2045,12 @@ main(int ac, char **av)
 	 * will not restart on SIGHUP since it no longer makes sense.
 	 */
 	alarm(0);
-	signal(SIGALRM, SIG_DFL);
-	signal(SIGHUP, SIG_DFL);
-	signal(SIGTERM, SIG_DFL);
-	signal(SIGQUIT, SIG_DFL);
-	signal(SIGCHLD, SIG_DFL);
-	signal(SIGINT, SIG_DFL);
+	ssh_signal(SIGALRM, SIG_DFL);
+	ssh_signal(SIGHUP, SIG_DFL);
+	ssh_signal(SIGTERM, SIG_DFL);
+	ssh_signal(SIGQUIT, SIG_DFL);
+	ssh_signal(SIGCHLD, SIG_DFL);
+	ssh_signal(SIGINT, SIG_DFL);
 
 	/*
 	 * Register our connection.  This turns encryption off because we do
@@ -2109,7 +2111,7 @@ main(int ac, char **av)
 	 * mode; it is just annoying to have the server exit just when you
 	 * are about to discover the bug.
 	 */
-	signal(SIGALRM, grace_alarm_handler);
+	ssh_signal(SIGALRM, grace_alarm_handler);
 	if (!debug_flag)
 		alarm(options.login_grace_time);
 
@@ -2167,7 +2169,7 @@ main(int ac, char **av)
 	 * authentication.
 	 */
 	alarm(0);
-	signal(SIGALRM, SIG_DFL);
+	ssh_signal(SIGALRM, SIG_DFL);
 	authctxt->authenticated = 1;
 	if (startup_pipe != -1) {
 		close(startup_pipe);