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);