mirror of git://anongit.mindrot.org/openssh.git
upstream: restore blocking status on stdio fds before close
ssh(1) needs to set file descriptors to non-blocking mode to operate
but it was not restoring the original state on exit. This could cause
problems with fds shared with other programs via the shell, e.g.
> $ cat > test.sh << _EOF
> #!/bin/sh
> {
> ssh -Fnone -oLogLevel=verbose ::1 hostname
> cat /usr/share/dict/words
> } | sleep 10
> _EOF
> $ ./test.sh
> Authenticated to ::1 ([::1]:22).
> Transferred: sent 2352, received 2928 bytes, in 0.1 seconds
> Bytes per second: sent 44338.9, received 55197.4
> cat: stdout: Resource temporarily unavailable
This restores the blocking status for fds 0,1,2 (stdio) before ssh(1)
abandons/closes them.
This was reported as bz3280 and GHPR246; ok dtucker@
OpenBSD-Commit-ID: 8cc67346f05aa85a598bddf2383fcfcc3aae61ce
This commit is contained in:
djm@openbsd.org
Damien Miller
parent
c4902e1a65
commit
7be4ac8136
67
channels.c
67
channels.c
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@ -1,4 +1,4 @@
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/* $OpenBSD: channels.c,v 1.406 2021/04/03 06:18:40 djm Exp $ */
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/* $OpenBSD: channels.c,v 1.407 2021/05/19 01:24:05 djm Exp $ */
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/*
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* Author: Tatu Ylonen <ylo@cs.hut.fi>
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* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
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@ -333,7 +333,27 @@ channel_register_fds(struct ssh *ssh, Channel *c, int rfd, int wfd, int efd,
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#endif
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/* enable nonblocking mode */
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if (nonblock) {
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c->restore_block = 0;
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if (nonblock == CHANNEL_NONBLOCK_STDIO) {
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/*
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* Special handling for stdio file descriptors: do not set
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* non-blocking mode if they are TTYs. Otherwise prepare to
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* restore their blocking state on exit to avoid interfering
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* with other programs that follow.
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*/
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if (rfd != -1 && !isatty(rfd) && fcntl(rfd, F_GETFL) == 0) {
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c->restore_block |= CHANNEL_RESTORE_RFD;
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set_nonblock(rfd);
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}
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if (wfd != -1 && !isatty(wfd) && fcntl(wfd, F_GETFL) == 0) {
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c->restore_block |= CHANNEL_RESTORE_WFD;
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set_nonblock(wfd);
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}
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if (efd != -1 && !isatty(efd) && fcntl(efd, F_GETFL) == 0) {
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c->restore_block |= CHANNEL_RESTORE_EFD;
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set_nonblock(efd);
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}
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} else if (nonblock) {
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if (rfd != -1)
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set_nonblock(rfd);
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if (wfd != -1)
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@ -422,17 +442,23 @@ channel_find_maxfd(struct ssh_channels *sc)
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}
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int
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channel_close_fd(struct ssh *ssh, int *fdp)
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channel_close_fd(struct ssh *ssh, Channel *c, int *fdp)
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{
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struct ssh_channels *sc = ssh->chanctxt;
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int ret = 0, fd = *fdp;
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int ret, fd = *fdp;
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if (fd != -1) {
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ret = close(fd);
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*fdp = -1;
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if (fd == sc->channel_max_fd)
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channel_find_maxfd(sc);
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}
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if (fd == -1)
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return 0;
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if ((*fdp == c->rfd && (c->restore_block & CHANNEL_RESTORE_RFD) != 0) ||
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(*fdp == c->wfd && (c->restore_block & CHANNEL_RESTORE_WFD) != 0) ||
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(*fdp == c->efd && (c->restore_block & CHANNEL_RESTORE_EFD) != 0))
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(void)fcntl(*fdp, F_SETFL, 0); /* restore blocking */
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ret = close(fd);
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*fdp = -1;
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if (fd == sc->channel_max_fd)
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channel_find_maxfd(sc);
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return ret;
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}
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@ -442,13 +468,13 @@ channel_close_fds(struct ssh *ssh, Channel *c)
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{
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int sock = c->sock, rfd = c->rfd, wfd = c->wfd, efd = c->efd;
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channel_close_fd(ssh, &c->sock);
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channel_close_fd(ssh, c, &c->sock);
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if (rfd != sock)
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channel_close_fd(ssh, &c->rfd);
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channel_close_fd(ssh, c, &c->rfd);
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if (wfd != sock && wfd != rfd)
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channel_close_fd(ssh, &c->wfd);
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channel_close_fd(ssh, c, &c->wfd);
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if (efd != sock && efd != rfd && efd != wfd)
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channel_close_fd(ssh, &c->efd);
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channel_close_fd(ssh, c, &c->efd);
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}
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static void
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@ -702,7 +728,7 @@ channel_stop_listening(struct ssh *ssh)
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case SSH_CHANNEL_X11_LISTENER:
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case SSH_CHANNEL_UNIX_LISTENER:
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case SSH_CHANNEL_RUNIX_LISTENER:
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channel_close_fd(ssh, &c->sock);
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channel_close_fd(ssh, c, &c->sock);
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channel_free(ssh, c);
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break;
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}
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@ -1491,7 +1517,8 @@ channel_decode_socks5(Channel *c, struct sshbuf *input, struct sshbuf *output)
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Channel *
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channel_connect_stdio_fwd(struct ssh *ssh,
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const char *host_to_connect, u_short port_to_connect, int in, int out)
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const char *host_to_connect, u_short port_to_connect,
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int in, int out, int nonblock)
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{
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Channel *c;
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@ -1499,7 +1526,7 @@ channel_connect_stdio_fwd(struct ssh *ssh,
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c = channel_new(ssh, "stdio-forward", SSH_CHANNEL_OPENING, in, out,
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-1, CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
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0, "stdio-forward", /*nonblock*/0);
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0, "stdio-forward", nonblock);
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c->path = xstrdup(host_to_connect);
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c->host_port = port_to_connect;
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@ -1649,7 +1676,7 @@ channel_post_x11_listener(struct ssh *ssh, Channel *c,
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if (c->single_connection) {
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oerrno = errno;
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debug2("single_connection: closing X11 listener.");
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channel_close_fd(ssh, &c->sock);
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channel_close_fd(ssh, c, &c->sock);
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chan_mark_dead(ssh, c);
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errno = oerrno;
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}
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@ -2058,7 +2085,7 @@ channel_handle_efd_write(struct ssh *ssh, Channel *c,
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return 1;
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if (len <= 0) {
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debug2("channel %d: closing write-efd %d", c->self, c->efd);
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channel_close_fd(ssh, &c->efd);
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channel_close_fd(ssh, c, &c->efd);
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} else {
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if ((r = sshbuf_consume(c->extended, len)) != 0)
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fatal_fr(r, "channel %i: consume", c->self);
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@ -2087,7 +2114,7 @@ channel_handle_efd_read(struct ssh *ssh, Channel *c,
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return 1;
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if (len <= 0) {
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debug2("channel %d: closing read-efd %d", c->self, c->efd);
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channel_close_fd(ssh, &c->efd);
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channel_close_fd(ssh, c, &c->efd);
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} else if (c->extended_usage == CHAN_EXTENDED_IGNORE)
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debug3("channel %d: discard efd", c->self);
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else if ((r = sshbuf_put(c->extended, buf, len)) != 0)
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17
channels.h
17
channels.h
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@ -1,4 +1,4 @@
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/* $OpenBSD: channels.h,v 1.137 2021/04/03 06:18:40 djm Exp $ */
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/* $OpenBSD: channels.h,v 1.138 2021/05/19 01:24:05 djm Exp $ */
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/*
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* Author: Tatu Ylonen <ylo@cs.hut.fi>
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@ -63,6 +63,16 @@
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#define CHANNEL_CANCEL_PORT_STATIC -1
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/* nonblocking flags for channel_new */
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#define CHANNEL_NONBLOCK_LEAVE 0 /* don't modify non-blocking state */
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#define CHANNEL_NONBLOCK_SET 1 /* set non-blocking state */
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#define CHANNEL_NONBLOCK_STDIO 2 /* set non-blocking and restore on close */
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/* c->restore_block mask flags */
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#define CHANNEL_RESTORE_RFD 0x01
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#define CHANNEL_RESTORE_WFD 0x02
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#define CHANNEL_RESTORE_EFD 0x04
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/* TCP forwarding */
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#define FORWARD_DENY 0
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#define FORWARD_REMOTE (1)
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@ -139,6 +149,7 @@ struct Channel {
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* to a matching pre-select handler.
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* this way post-select handlers are not
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* accidentally called if a FD gets reused */
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int restore_block; /* fd mask to restore blocking status */
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struct sshbuf *input; /* data read from socket, to be sent over
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* encrypted connection */
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struct sshbuf *output; /* data received over encrypted connection for
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@ -266,7 +277,7 @@ void channel_register_filter(struct ssh *, int, channel_infilter_fn *,
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void channel_register_status_confirm(struct ssh *, int,
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channel_confirm_cb *, channel_confirm_abandon_cb *, void *);
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void channel_cancel_cleanup(struct ssh *, int);
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int channel_close_fd(struct ssh *, int *);
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int channel_close_fd(struct ssh *, Channel *, int *);
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void channel_send_window_changes(struct ssh *);
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/* mux proxy support */
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@ -313,7 +324,7 @@ Channel *channel_connect_to_port(struct ssh *, const char *, u_short,
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char *, char *, int *, const char **);
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Channel *channel_connect_to_path(struct ssh *, const char *, char *, char *);
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Channel *channel_connect_stdio_fwd(struct ssh *, const char*,
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u_short, int, int);
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u_short, int, int, int);
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Channel *channel_connect_by_listen_address(struct ssh *, const char *,
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u_short, char *, char *);
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Channel *channel_connect_by_listen_path(struct ssh *, const char *,
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10
clientloop.c
10
clientloop.c
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@ -1,4 +1,4 @@
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/* $OpenBSD: clientloop.c,v 1.362 2021/05/04 22:53:52 dtucker Exp $ */
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/* $OpenBSD: clientloop.c,v 1.363 2021/05/19 01:24:05 djm Exp $ */
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/*
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* Author: Tatu Ylonen <ylo@cs.hut.fi>
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* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
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@ -1405,14 +1405,6 @@ client_loop(struct ssh *ssh, int have_pty, int escape_char_arg,
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if (have_pty)
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leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
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/* restore blocking io */
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if (!isatty(fileno(stdin)))
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unset_nonblock(fileno(stdin));
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if (!isatty(fileno(stdout)))
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unset_nonblock(fileno(stdout));
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if (!isatty(fileno(stderr)))
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unset_nonblock(fileno(stderr));
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/*
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* If there was no shell or command requested, there will be no remote
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* exit status to be returned. In that case, clear error code if the
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21
mux.c
21
mux.c
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@ -1,4 +1,4 @@
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/* $OpenBSD: mux.c,v 1.87 2021/04/03 06:18:40 djm Exp $ */
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/* $OpenBSD: mux.c,v 1.88 2021/05/19 01:24:05 djm Exp $ */
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/*
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* Copyright (c) 2002-2008 Damien Miller <djm@openbsd.org>
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*
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@ -452,14 +452,6 @@ mux_master_process_new_session(struct ssh *ssh, u_int rid,
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if (cctx->want_tty && tcgetattr(new_fd[0], &cctx->tio) == -1)
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error_f("tcgetattr: %s", strerror(errno));
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/* enable nonblocking unless tty */
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if (!isatty(new_fd[0]))
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set_nonblock(new_fd[0]);
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if (!isatty(new_fd[1]))
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set_nonblock(new_fd[1]);
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if (!isatty(new_fd[2]))
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set_nonblock(new_fd[2]);
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window = CHAN_SES_WINDOW_DEFAULT;
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packetmax = CHAN_SES_PACKET_DEFAULT;
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if (cctx->want_tty) {
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@ -469,7 +461,7 @@ mux_master_process_new_session(struct ssh *ssh, u_int rid,
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nc = channel_new(ssh, "session", SSH_CHANNEL_OPENING,
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new_fd[0], new_fd[1], new_fd[2], window, packetmax,
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CHAN_EXTENDED_WRITE, "client-session", /*nonblock*/0);
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CHAN_EXTENDED_WRITE, "client-session", CHANNEL_NONBLOCK_STDIO);
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nc->ctl_chan = c->self; /* link session -> control channel */
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c->remote_id = nc->self; /* link control -> session channel */
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@ -1025,13 +1017,8 @@ mux_master_process_stdio_fwd(struct ssh *ssh, u_int rid,
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}
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}
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/* enable nonblocking unless tty */
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if (!isatty(new_fd[0]))
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set_nonblock(new_fd[0]);
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if (!isatty(new_fd[1]))
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set_nonblock(new_fd[1]);
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nc = channel_connect_stdio_fwd(ssh, chost, cport, new_fd[0], new_fd[1]);
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nc = channel_connect_stdio_fwd(ssh, chost, cport, new_fd[0], new_fd[1],
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CHANNEL_NONBLOCK_STDIO);
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free(chost);
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nc->ctl_chan = c->self; /* link session -> control channel */
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8
nchan.c
8
nchan.c
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@ -1,4 +1,4 @@
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/* $OpenBSD: nchan.c,v 1.72 2021/01/27 09:26:54 djm Exp $ */
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/* $OpenBSD: nchan.c,v 1.73 2021/05/19 01:24:05 djm Exp $ */
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/*
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* Copyright (c) 1999, 2000, 2001, 2002 Markus Friedl. All rights reserved.
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*
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@ -384,7 +384,7 @@ chan_shutdown_write(struct ssh *ssh, Channel *c)
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c->istate, c->ostate, strerror(errno));
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}
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} else {
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if (channel_close_fd(ssh, &c->wfd) < 0) {
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if (channel_close_fd(ssh, c, &c->wfd) < 0) {
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logit_f("channel %d: close() failed for "
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"fd %d [i%d o%d]: %.100s", c->self, c->wfd,
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c->istate, c->ostate, strerror(errno));
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@ -412,7 +412,7 @@ chan_shutdown_read(struct ssh *ssh, Channel *c)
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c->istate, c->ostate, strerror(errno));
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}
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} else {
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if (channel_close_fd(ssh, &c->rfd) < 0) {
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if (channel_close_fd(ssh, c, &c->rfd) < 0) {
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logit_f("channel %d: close() failed for "
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"fd %d [i%d o%d]: %.100s", c->self, c->rfd,
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c->istate, c->ostate, strerror(errno));
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@ -431,7 +431,7 @@ chan_shutdown_extended_read(struct ssh *ssh, Channel *c)
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debug_f("channel %d: (i%d o%d sock %d wfd %d efd %d [%s])",
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c->self, c->istate, c->ostate, c->sock, c->rfd, c->efd,
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channel_format_extended_usage(c));
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if (channel_close_fd(ssh, &c->efd) < 0) {
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if (channel_close_fd(ssh, c, &c->efd) < 0) {
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logit_f("channel %d: close() failed for "
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"extended fd %d [i%d o%d]: %.100s", c->self, c->efd,
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c->istate, c->ostate, strerror(errno));
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17
ssh.c
17
ssh.c
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@ -1,4 +1,4 @@
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/* $OpenBSD: ssh.c,v 1.556 2021/05/17 11:43:16 djm Exp $ */
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/* $OpenBSD: ssh.c,v 1.557 2021/05/19 01:24:05 djm Exp $ */
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/*
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* Author: Tatu Ylonen <ylo@cs.hut.fi>
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* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
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@ -1876,9 +1876,10 @@ ssh_init_stdio_forwarding(struct ssh *ssh)
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if ((in = dup(STDIN_FILENO)) == -1 ||
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(out = dup(STDOUT_FILENO)) == -1)
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fatal("channel_connect_stdio_fwd: dup() in/out failed");
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fatal_f("dup() in/out failed");
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if ((c = channel_connect_stdio_fwd(ssh, options.stdio_forward_host,
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options.stdio_forward_port, in, out)) == NULL)
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options.stdio_forward_port, in, out,
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CHANNEL_NONBLOCK_STDIO)) == NULL)
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fatal_f("channel_connect_stdio_fwd failed");
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channel_register_cleanup(ssh, c->self, client_cleanup_stdio_fwd, 0);
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channel_register_open_confirm(ssh, c->self, ssh_stdio_confirm, NULL);
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@ -2074,14 +2075,6 @@ ssh_session2_open(struct ssh *ssh)
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if (in == -1 || out == -1 || err == -1)
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fatal("dup() in/out/err failed");
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/* enable nonblocking unless tty */
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if (!isatty(in))
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set_nonblock(in);
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if (!isatty(out))
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set_nonblock(out);
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if (!isatty(err))
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set_nonblock(err);
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window = CHAN_SES_WINDOW_DEFAULT;
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packetmax = CHAN_SES_PACKET_DEFAULT;
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if (tty_flag) {
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@ -2091,7 +2084,7 @@ ssh_session2_open(struct ssh *ssh)
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c = channel_new(ssh,
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"session", SSH_CHANNEL_OPENING, in, out, err,
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window, packetmax, CHAN_EXTENDED_WRITE,
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"client-session", /*nonblock*/0);
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"client-session", CHANNEL_NONBLOCK_STDIO);
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debug3_f("channel_new: %d", c->self);
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