use ppoll() instead of pselect()

with djm

1 files changed, 23 insertions, 22 deletions

diff --git a/usr.bin/ssh/sshd.c b/usr.bin/ssh/sshd.c
index ce419fe5ae4..78f5d647f60 100644
--- a/usr.bin/ssh/sshd.c
+++ b/usr.bin/ssh/sshd.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: sshd.c,v 1.578 2021/07/19 02:21:50 dtucker Exp $ */
+/* $OpenBSD: sshd.c,v 1.579 2021/11/14 18:47:43 deraadt Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -55,6 +55,7 @@
 #include <fcntl.h>
 #include <netdb.h>
 #include <paths.h>
+#include <poll.h>
 #include <pwd.h>
 #include <signal.h>
 #include <stdio.h>
@@ -1079,8 +1080,8 @@ server_listen(void)
 static void
 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s)
 {
-	fd_set *fdset;
-	int i, j, ret, maxfd;
+	struct pollfd *pfd = NULL;
+	int i, j, ret;
 	int ostartups = -1, startups = 0, listening = 0, lameduck = 0;
 	int startup_p[2] = { -1 , -1 };
 	char c = 0;
@@ -1090,11 +1091,6 @@ server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s)
 	sigset_t nsigset, osigset;
 
 	/* setup fd set for accept */
-	fdset = NULL;
-	maxfd = 0;
-	for (i = 0; i < num_listen_socks; i++)
-		if (listen_socks[i] > maxfd)
-			maxfd = listen_socks[i];
 	/* pipes connected to unauthenticated child sshd processes */
 	startup_pipes = xcalloc(options.max_startups, sizeof(int));
 	startup_flags = xcalloc(options.max_startups, sizeof(int));
@@ -1104,7 +1100,7 @@ server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s)
 	/*
 	 * Prepare signal mask that we use to block signals that might set
 	 * received_sigterm or received_sighup, so that we are guaranteed
-	 * to immediately wake up the pselect if a signal is received after
+	 * to immediately wake up the ppoll if a signal is received after
 	 * the flag is checked.
 	 */
 	sigemptyset(&nsigset);
@@ -1113,6 +1109,9 @@ server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s)
 	sigaddset(&nsigset, SIGTERM);
 	sigaddset(&nsigset, SIGQUIT);
 
+	pfd = xcalloc(num_listen_socks + options.max_startups,
+	    sizeof(struct pollfd));
+
 	/*
 	 * Stay listening for connections until the system crashes or
 	 * the daemon is killed with a signal.
@@ -1144,27 +1143,29 @@ server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s)
 				sighup_restart();
 			}
 		}
-		free(fdset);
-		fdset = xcalloc(howmany(maxfd + 1, NFDBITS),
-		    sizeof(fd_mask));
 
-		for (i = 0; i < num_listen_socks; i++)
-			FD_SET(listen_socks[i], fdset);
-		for (i = 0; i < options.max_startups; i++)
+		for (i = 0; i < num_listen_socks; i++) {
+			pfd[i].fd = listen_socks[i];
+			pfd[i].events = POLLIN;
+		}
+		for (i = 0; i < options.max_startups; i++) {
+			pfd[num_listen_socks+i].fd = startup_pipes[i];
 			if (startup_pipes[i] != -1)
-				FD_SET(startup_pipes[i], fdset);
+				pfd[num_listen_socks+i].events = POLLIN;
+		}
 
 		/* Wait until a connection arrives or a child exits. */
-		ret = pselect(maxfd+1, fdset, NULL, NULL, NULL, &osigset);
+		ret = ppoll(pfd, num_listen_socks + options.max_startups,
+		    NULL, &osigset);
 		if (ret == -1 && errno != EINTR)
-			error("pselect: %.100s", strerror(errno));
+			error("ppoll: %.100s", strerror(errno));
 		sigprocmask(SIG_SETMASK, &osigset, NULL);
 		if (ret == -1)
 			continue;
 
 		for (i = 0; i < options.max_startups; i++) {
 			if (startup_pipes[i] == -1 ||
-			    !FD_ISSET(startup_pipes[i], fdset))
+			    !(pfd[num_listen_socks+i].revents & POLLIN))
 				continue;
 			switch (read(startup_pipes[i], &c, sizeof(c))) {
 			case -1:
@@ -1195,7 +1196,7 @@ server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s)
 			}
 		}
 		for (i = 0; i < num_listen_socks; i++) {
-			if (!FD_ISSET(listen_socks[i], fdset))
+			if (!(pfd[i].revents & POLLIN))
 				continue;
 			fromlen = sizeof(from);
 			*newsock = accept(listen_socks[i],
@@ -1232,8 +1233,6 @@ server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s)
 			for (j = 0; j < options.max_startups; j++)
 				if (startup_pipes[j] == -1) {
 					startup_pipes[j] = startup_p[0];
-					if (maxfd < startup_p[0])
-						maxfd = startup_p[0];
 					startups++;
 					startup_flags[j] = 1;
 					break;
@@ -1261,6 +1260,7 @@ server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s)
 					send_rexec_state(config_s[0], cfg);
 					close(config_s[0]);
 				}
+				free(pfd);
 				return;
 			}
 
@@ -1301,6 +1301,7 @@ server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s)
 					(void)atomicio(vwrite, startup_pipe,
 					    "\0", 1);
 				}
+				free(pfd);
 				return;
 			}