[openssh-commits] [openssh] 01/01: upstream: restore blocking status on stdio fds before close
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Wed May 19 11:52:34 AEST 2021
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djm pushed a commit to branch master
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commit 7be4ac813662f68e89f23c50de058a49aa32f7e4
Author: djm at openbsd.org <djm at openbsd.org>
Date: Wed May 19 01:24:05 2021 +0000
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
---
channels.c | 67 ++++++++++++++++++++++++++++++++++++++++++------------------
channels.h | 17 ++++++++++++---
clientloop.c | 10 +--------
mux.c | 21 ++++---------------
nchan.c | 8 ++++----
ssh.c | 17 +++++----------
6 files changed, 75 insertions(+), 65 deletions(-)
diff --git a/channels.c b/channels.c
index 32d1f617..0024f751 100644
--- a/channels.c
+++ b/channels.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: channels.c,v 1.406 2021/04/03 06:18:40 djm Exp $ */
+/* $OpenBSD: channels.c,v 1.407 2021/05/19 01:24:05 djm Exp $ */
/*
* Author: Tatu Ylonen <ylo at cs.hut.fi>
* Copyright (c) 1995 Tatu Ylonen <ylo at cs.hut.fi>, Espoo, Finland
@@ -333,7 +333,27 @@ channel_register_fds(struct ssh *ssh, Channel *c, int rfd, int wfd, int efd,
#endif
/* enable nonblocking mode */
- if (nonblock) {
+ c->restore_block = 0;
+ if (nonblock == CHANNEL_NONBLOCK_STDIO) {
+ /*
+ * Special handling for stdio file descriptors: do not set
+ * non-blocking mode if they are TTYs. Otherwise prepare to
+ * restore their blocking state on exit to avoid interfering
+ * with other programs that follow.
+ */
+ if (rfd != -1 && !isatty(rfd) && fcntl(rfd, F_GETFL) == 0) {
+ c->restore_block |= CHANNEL_RESTORE_RFD;
+ set_nonblock(rfd);
+ }
+ if (wfd != -1 && !isatty(wfd) && fcntl(wfd, F_GETFL) == 0) {
+ c->restore_block |= CHANNEL_RESTORE_WFD;
+ set_nonblock(wfd);
+ }
+ if (efd != -1 && !isatty(efd) && fcntl(efd, F_GETFL) == 0) {
+ c->restore_block |= CHANNEL_RESTORE_EFD;
+ set_nonblock(efd);
+ }
+ } else if (nonblock) {
if (rfd != -1)
set_nonblock(rfd);
if (wfd != -1)
@@ -422,17 +442,23 @@ channel_find_maxfd(struct ssh_channels *sc)
}
int
-channel_close_fd(struct ssh *ssh, int *fdp)
+channel_close_fd(struct ssh *ssh, Channel *c, int *fdp)
{
struct ssh_channels *sc = ssh->chanctxt;
- int ret = 0, fd = *fdp;
+ int ret, fd = *fdp;
- if (fd != -1) {
- ret = close(fd);
- *fdp = -1;
- if (fd == sc->channel_max_fd)
- channel_find_maxfd(sc);
- }
+ if (fd == -1)
+ return 0;
+
+ if ((*fdp == c->rfd && (c->restore_block & CHANNEL_RESTORE_RFD) != 0) ||
+ (*fdp == c->wfd && (c->restore_block & CHANNEL_RESTORE_WFD) != 0) ||
+ (*fdp == c->efd && (c->restore_block & CHANNEL_RESTORE_EFD) != 0))
+ (void)fcntl(*fdp, F_SETFL, 0); /* restore blocking */
+
+ ret = close(fd);
+ *fdp = -1;
+ if (fd == sc->channel_max_fd)
+ channel_find_maxfd(sc);
return ret;
}
@@ -442,13 +468,13 @@ channel_close_fds(struct ssh *ssh, Channel *c)
{
int sock = c->sock, rfd = c->rfd, wfd = c->wfd, efd = c->efd;
- channel_close_fd(ssh, &c->sock);
+ channel_close_fd(ssh, c, &c->sock);
if (rfd != sock)
- channel_close_fd(ssh, &c->rfd);
+ channel_close_fd(ssh, c, &c->rfd);
if (wfd != sock && wfd != rfd)
- channel_close_fd(ssh, &c->wfd);
+ channel_close_fd(ssh, c, &c->wfd);
if (efd != sock && efd != rfd && efd != wfd)
- channel_close_fd(ssh, &c->efd);
+ channel_close_fd(ssh, c, &c->efd);
}
static void
@@ -702,7 +728,7 @@ channel_stop_listening(struct ssh *ssh)
case SSH_CHANNEL_X11_LISTENER:
case SSH_CHANNEL_UNIX_LISTENER:
case SSH_CHANNEL_RUNIX_LISTENER:
- channel_close_fd(ssh, &c->sock);
+ channel_close_fd(ssh, c, &c->sock);
channel_free(ssh, c);
break;
}
@@ -1491,7 +1517,8 @@ channel_decode_socks5(Channel *c, struct sshbuf *input, struct sshbuf *output)
Channel *
channel_connect_stdio_fwd(struct ssh *ssh,
- const char *host_to_connect, u_short port_to_connect, int in, int out)
+ const char *host_to_connect, u_short port_to_connect,
+ int in, int out, int nonblock)
{
Channel *c;
@@ -1499,7 +1526,7 @@ channel_connect_stdio_fwd(struct ssh *ssh,
c = channel_new(ssh, "stdio-forward", SSH_CHANNEL_OPENING, in, out,
-1, CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
- 0, "stdio-forward", /*nonblock*/0);
+ 0, "stdio-forward", nonblock);
c->path = xstrdup(host_to_connect);
c->host_port = port_to_connect;
@@ -1649,7 +1676,7 @@ channel_post_x11_listener(struct ssh *ssh, Channel *c,
if (c->single_connection) {
oerrno = errno;
debug2("single_connection: closing X11 listener.");
- channel_close_fd(ssh, &c->sock);
+ channel_close_fd(ssh, c, &c->sock);
chan_mark_dead(ssh, c);
errno = oerrno;
}
@@ -2058,7 +2085,7 @@ channel_handle_efd_write(struct ssh *ssh, Channel *c,
return 1;
if (len <= 0) {
debug2("channel %d: closing write-efd %d", c->self, c->efd);
- channel_close_fd(ssh, &c->efd);
+ channel_close_fd(ssh, c, &c->efd);
} else {
if ((r = sshbuf_consume(c->extended, len)) != 0)
fatal_fr(r, "channel %i: consume", c->self);
@@ -2087,7 +2114,7 @@ channel_handle_efd_read(struct ssh *ssh, Channel *c,
return 1;
if (len <= 0) {
debug2("channel %d: closing read-efd %d", c->self, c->efd);
- channel_close_fd(ssh, &c->efd);
+ channel_close_fd(ssh, c, &c->efd);
} else if (c->extended_usage == CHAN_EXTENDED_IGNORE)
debug3("channel %d: discard efd", c->self);
else if ((r = sshbuf_put(c->extended, buf, len)) != 0)
diff --git a/channels.h b/channels.h
index 378d987c..6bf86b00 100644
--- a/channels.h
+++ b/channels.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: channels.h,v 1.137 2021/04/03 06:18:40 djm Exp $ */
+/* $OpenBSD: channels.h,v 1.138 2021/05/19 01:24:05 djm Exp $ */
/*
* Author: Tatu Ylonen <ylo at cs.hut.fi>
@@ -63,6 +63,16 @@
#define CHANNEL_CANCEL_PORT_STATIC -1
+/* nonblocking flags for channel_new */
+#define CHANNEL_NONBLOCK_LEAVE 0 /* don't modify non-blocking state */
+#define CHANNEL_NONBLOCK_SET 1 /* set non-blocking state */
+#define CHANNEL_NONBLOCK_STDIO 2 /* set non-blocking and restore on close */
+
+/* c->restore_block mask flags */
+#define CHANNEL_RESTORE_RFD 0x01
+#define CHANNEL_RESTORE_WFD 0x02
+#define CHANNEL_RESTORE_EFD 0x04
+
/* TCP forwarding */
#define FORWARD_DENY 0
#define FORWARD_REMOTE (1)
@@ -139,6 +149,7 @@ struct Channel {
* to a matching pre-select handler.
* this way post-select handlers are not
* accidentally called if a FD gets reused */
+ int restore_block; /* fd mask to restore blocking status */
struct sshbuf *input; /* data read from socket, to be sent over
* encrypted connection */
struct sshbuf *output; /* data received over encrypted connection for
@@ -266,7 +277,7 @@ void channel_register_filter(struct ssh *, int, channel_infilter_fn *,
void channel_register_status_confirm(struct ssh *, int,
channel_confirm_cb *, channel_confirm_abandon_cb *, void *);
void channel_cancel_cleanup(struct ssh *, int);
-int channel_close_fd(struct ssh *, int *);
+int channel_close_fd(struct ssh *, Channel *, int *);
void channel_send_window_changes(struct ssh *);
/* mux proxy support */
@@ -313,7 +324,7 @@ Channel *channel_connect_to_port(struct ssh *, const char *, u_short,
char *, char *, int *, const char **);
Channel *channel_connect_to_path(struct ssh *, const char *, char *, char *);
Channel *channel_connect_stdio_fwd(struct ssh *, const char*,
- u_short, int, int);
+ u_short, int, int, int);
Channel *channel_connect_by_listen_address(struct ssh *, const char *,
u_short, char *, char *);
Channel *channel_connect_by_listen_path(struct ssh *, const char *,
diff --git a/clientloop.c b/clientloop.c
index 219f0e90..bdd67686 100644
--- a/clientloop.c
+++ b/clientloop.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: clientloop.c,v 1.362 2021/05/04 22:53:52 dtucker Exp $ */
+/* $OpenBSD: clientloop.c,v 1.363 2021/05/19 01:24:05 djm Exp $ */
/*
* Author: Tatu Ylonen <ylo at cs.hut.fi>
* Copyright (c) 1995 Tatu Ylonen <ylo at cs.hut.fi>, Espoo, Finland
@@ -1405,14 +1405,6 @@ client_loop(struct ssh *ssh, int have_pty, int escape_char_arg,
if (have_pty)
leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
- /* restore blocking io */
- if (!isatty(fileno(stdin)))
- unset_nonblock(fileno(stdin));
- if (!isatty(fileno(stdout)))
- unset_nonblock(fileno(stdout));
- if (!isatty(fileno(stderr)))
- unset_nonblock(fileno(stderr));
-
/*
* If there was no shell or command requested, there will be no remote
* exit status to be returned. In that case, clear error code if the
diff --git a/mux.c b/mux.c
index faf4ef1e..9454bfed 100644
--- a/mux.c
+++ b/mux.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: mux.c,v 1.87 2021/04/03 06:18:40 djm Exp $ */
+/* $OpenBSD: mux.c,v 1.88 2021/05/19 01:24:05 djm Exp $ */
/*
* Copyright (c) 2002-2008 Damien Miller <djm at openbsd.org>
*
@@ -452,14 +452,6 @@ mux_master_process_new_session(struct ssh *ssh, u_int rid,
if (cctx->want_tty && tcgetattr(new_fd[0], &cctx->tio) == -1)
error_f("tcgetattr: %s", strerror(errno));
- /* enable nonblocking unless tty */
- if (!isatty(new_fd[0]))
- set_nonblock(new_fd[0]);
- if (!isatty(new_fd[1]))
- set_nonblock(new_fd[1]);
- if (!isatty(new_fd[2]))
- set_nonblock(new_fd[2]);
-
window = CHAN_SES_WINDOW_DEFAULT;
packetmax = CHAN_SES_PACKET_DEFAULT;
if (cctx->want_tty) {
@@ -469,7 +461,7 @@ mux_master_process_new_session(struct ssh *ssh, u_int rid,
nc = channel_new(ssh, "session", SSH_CHANNEL_OPENING,
new_fd[0], new_fd[1], new_fd[2], window, packetmax,
- CHAN_EXTENDED_WRITE, "client-session", /*nonblock*/0);
+ CHAN_EXTENDED_WRITE, "client-session", CHANNEL_NONBLOCK_STDIO);
nc->ctl_chan = c->self; /* link session -> control channel */
c->remote_id = nc->self; /* link control -> session channel */
@@ -1025,13 +1017,8 @@ mux_master_process_stdio_fwd(struct ssh *ssh, u_int rid,
}
}
- /* enable nonblocking unless tty */
- if (!isatty(new_fd[0]))
- set_nonblock(new_fd[0]);
- if (!isatty(new_fd[1]))
- set_nonblock(new_fd[1]);
-
- nc = channel_connect_stdio_fwd(ssh, chost, cport, new_fd[0], new_fd[1]);
+ nc = channel_connect_stdio_fwd(ssh, chost, cport, new_fd[0], new_fd[1],
+ CHANNEL_NONBLOCK_STDIO);
free(chost);
nc->ctl_chan = c->self; /* link session -> control channel */
diff --git a/nchan.c b/nchan.c
index 4a4494b8..7ef3a350 100644
--- a/nchan.c
+++ b/nchan.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: nchan.c,v 1.72 2021/01/27 09:26:54 djm Exp $ */
+/* $OpenBSD: nchan.c,v 1.73 2021/05/19 01:24:05 djm Exp $ */
/*
* Copyright (c) 1999, 2000, 2001, 2002 Markus Friedl. All rights reserved.
*
@@ -384,7 +384,7 @@ chan_shutdown_write(struct ssh *ssh, Channel *c)
c->istate, c->ostate, strerror(errno));
}
} else {
- if (channel_close_fd(ssh, &c->wfd) < 0) {
+ if (channel_close_fd(ssh, c, &c->wfd) < 0) {
logit_f("channel %d: close() failed for "
"fd %d [i%d o%d]: %.100s", c->self, c->wfd,
c->istate, c->ostate, strerror(errno));
@@ -412,7 +412,7 @@ chan_shutdown_read(struct ssh *ssh, Channel *c)
c->istate, c->ostate, strerror(errno));
}
} else {
- if (channel_close_fd(ssh, &c->rfd) < 0) {
+ if (channel_close_fd(ssh, c, &c->rfd) < 0) {
logit_f("channel %d: close() failed for "
"fd %d [i%d o%d]: %.100s", c->self, c->rfd,
c->istate, c->ostate, strerror(errno));
@@ -431,7 +431,7 @@ chan_shutdown_extended_read(struct ssh *ssh, Channel *c)
debug_f("channel %d: (i%d o%d sock %d wfd %d efd %d [%s])",
c->self, c->istate, c->ostate, c->sock, c->rfd, c->efd,
channel_format_extended_usage(c));
- if (channel_close_fd(ssh, &c->efd) < 0) {
+ if (channel_close_fd(ssh, c, &c->efd) < 0) {
logit_f("channel %d: close() failed for "
"extended fd %d [i%d o%d]: %.100s", c->self, c->efd,
c->istate, c->ostate, strerror(errno));
diff --git a/ssh.c b/ssh.c
index 696dc3bc..6243db76 100644
--- a/ssh.c
+++ b/ssh.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssh.c,v 1.556 2021/05/17 11:43:16 djm Exp $ */
+/* $OpenBSD: ssh.c,v 1.557 2021/05/19 01:24:05 djm Exp $ */
/*
* Author: Tatu Ylonen <ylo at cs.hut.fi>
* Copyright (c) 1995 Tatu Ylonen <ylo at cs.hut.fi>, Espoo, Finland
@@ -1876,9 +1876,10 @@ ssh_init_stdio_forwarding(struct ssh *ssh)
if ((in = dup(STDIN_FILENO)) == -1 ||
(out = dup(STDOUT_FILENO)) == -1)
- fatal("channel_connect_stdio_fwd: dup() in/out failed");
+ fatal_f("dup() in/out failed");
if ((c = channel_connect_stdio_fwd(ssh, options.stdio_forward_host,
- options.stdio_forward_port, in, out)) == NULL)
+ options.stdio_forward_port, in, out,
+ CHANNEL_NONBLOCK_STDIO)) == NULL)
fatal_f("channel_connect_stdio_fwd failed");
channel_register_cleanup(ssh, c->self, client_cleanup_stdio_fwd, 0);
channel_register_open_confirm(ssh, c->self, ssh_stdio_confirm, NULL);
@@ -2074,14 +2075,6 @@ ssh_session2_open(struct ssh *ssh)
if (in == -1 || out == -1 || err == -1)
fatal("dup() in/out/err failed");
- /* enable nonblocking unless tty */
- if (!isatty(in))
- set_nonblock(in);
- if (!isatty(out))
- set_nonblock(out);
- if (!isatty(err))
- set_nonblock(err);
-
window = CHAN_SES_WINDOW_DEFAULT;
packetmax = CHAN_SES_PACKET_DEFAULT;
if (tty_flag) {
@@ -2091,7 +2084,7 @@ ssh_session2_open(struct ssh *ssh)
c = channel_new(ssh,
"session", SSH_CHANNEL_OPENING, in, out, err,
window, packetmax, CHAN_EXTENDED_WRITE,
- "client-session", /*nonblock*/0);
+ "client-session", CHANNEL_NONBLOCK_STDIO);
debug3_f("channel_new: %d", c->self);
--
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