upstream: When doing the fork+exec'ing for ssh-keysign, rearrange

the socket into fd3, so as to not mistakenly leak other fd forward
accidentally. ok djm

OpenBSD-Commit-ID: 24cc753f5aa2c6a7d0fbf62766adbc75cd785296

1 files changed, 9 insertions, 7 deletions

diff --git a/sshconnect2.c b/sshconnect2.c
index dffee90b1..d2b5d4c04 100644
--- a/sshconnect2.c
+++ b/sshconnect2.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: sshconnect2.c,v 1.303 2019/02/12 23:53:10 djm Exp $ */
+/* $OpenBSD: sshconnect2.c,v 1.304 2019/05/15 04:43:31 deraadt Exp $ */
 /*
  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
  * Copyright (c) 2008 Damien Miller.  All rights reserved.
@@ -1833,7 +1833,7 @@ ssh_keysign(struct ssh *ssh, struct sshkey *key, u_char **sigp, size_t *lenp,
         struct sshbuf *b;
         struct stat st;
         pid_t pid;
-        int i, r, to[2], from[2], status;
+        int r, to[2], from[2], status;
         int sock = ssh_packet_get_connection_in(ssh);
         u_char rversion = 0, version = 2;
         void (*osigchld)(int);
@@ -1863,8 +1863,6 @@ ssh_keysign(struct ssh *ssh, struct sshkey *key, u_char **sigp, size_t *lenp,
         }
         osigchld = signal(SIGCHLD, SIG_DFL);
         if (pid == 0) {
-                /* keep the socket on exec */
-                fcntl(sock, F_SETFD, 0);
                 close(from[0]);
                 if (dup2(from[1], STDOUT_FILENO) < 0)
                         fatal("%s: dup2: %s", __func__, strerror(errno));
@@ -1873,10 +1871,13 @@ ssh_keysign(struct ssh *ssh, struct sshkey *key, u_char **sigp, size_t *lenp,
                         fatal("%s: dup2: %s", __func__, strerror(errno));
                 close(from[1]);
                 close(to[0]);
-                /* Close everything but stdio and the socket */
-                for (i = STDERR_FILENO + 1; i < sock; i++)
-                        close(i);
+
+                if (dup2(sock, STDERR_FILENO + 1) < 0)
+                        fatal("%s: dup2: %s", __func__, strerror(errno));
+                sock = STDERR_FILENO + 1;
+                fcntl(sock, F_SETFD, 0);        /* keep the socket on exec */
                 closefrom(sock + 1);
+
                 debug3("%s: [child] pid=%ld, exec %s",
                     __func__, (long)getpid(), _PATH_SSH_KEY_SIGN);
                 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *)NULL);
@@ -1885,6 +1886,7 @@ ssh_keysign(struct ssh *ssh, struct sshkey *key, u_char **sigp, size_t *lenp,
         }
         close(from[1]);
         close(to[0]);
+        sock = STDIN_FILENO + 1;
 
         if ((b = sshbuf_new()) == NULL)
                 fatal("%s: sshbuf_new failed", __func__);