Attachment 1316 Details for Bug 1328 – Handle multiple $DISPLAYs

[patch] Handle multiple $DISPLAYs

openssh-4.5p1-multidisplay.patch (text/plain), 15.30 KB, created by David Woodhouse on 2007-07-06 01:15:52 AEST

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Creator: David Woodhouse

Created: 2007-07-06 01:15:52 AEST

Size: 15.30 KB

patch

obsolete

>diff -ur openssh-4.5p1/channels.c openssh-4.5p1-multidisplay/channels.c
>--- openssh-4.5p1/channels.c	2006-08-30 02:07:40.000000000 +0100
>+++ openssh-4.5p1-multidisplay/channels.c	2007-03-24 16:22:37.000000000 +0000
>@@ -96,6 +96,11 @@
>  */
> static int channel_max_fd = 0;
> 
>+/*
>+ * Flag indicating that channel fds have been modified, used to restart
>+ * preparations for select if necessary
>+ */
>+static int channel_fds_changed = 0;
> 
> /* -- tcp forwarding */
> 
>@@ -136,23 +141,31 @@
> /* Maximum number of fake X11 displays to try. */
> #define MAX_DISPLAYS  1000
> 
>-/* Saved X11 local (client) display. */
>-static char *x11_saved_display = NULL;
>-
>-/* Saved X11 authentication protocol name. */
>-static char *x11_saved_proto = NULL;
>+struct x11_fwd {
>+	/* Saved X11 local (client) display. */
>+	char *saved_display;
>+
>+	/* Saved X11 authentication protocol name. */
>+	char *saved_proto;
>+
>+	/* Saved X11 authentication data.  These are the real data. */
>+	u_char *saved_data;
>+	u_int saved_data_len;
> 
>-/* Saved X11 authentication data.  This is the real data. */
>-static char *x11_saved_data = NULL;
>-static u_int x11_saved_data_len = 0;
>+	/*
>+	 * Fake X11 authentication data.  This is what the server will be 
>+	 sending us; we should replace any occurrences with the real data.
>+	*/
>+	u_char *fake_data;
>+	u_int fake_data_len;
>+
>+	u_int usecount;
>+	struct x11_fwd *next;
>+};
> 
>-/*
>- * Fake X11 authentication data.  This is what the server will be sending us;
>- * we should replace any occurrences of this by the real data.
>- */
>-static u_char *x11_fake_data = NULL;
>-static u_int x11_fake_data_len;
>+static struct x11_fwd *x11_fwds = NULL;
> 
>+static void x11_put_fwd(struct x11_fwd *fwd);
> 
> /* -- agent forwarding */
> 
>@@ -218,6 +231,16 @@
> channel_register_fds(Channel *c, int rfd, int wfd, int efd,
>     int extusage, int nonblock)
> {
>+	c->rfd = rfd;
>+	c->wfd = wfd;
>+	c->sock = (rfd == wfd) ? rfd : -1;
>+	c->ctl_fd = -1; /* XXX: set elsewhere */
>+	c->efd = efd;
>+	channel_fds_changed = 1;
>+
>+	if (rfd == -1 && wfd == -1 && efd == -1)
>+		return;
>+
> 	/* Update the maximum file descriptor value. */
> 	channel_max_fd = MAX(channel_max_fd, rfd);
> 	channel_max_fd = MAX(channel_max_fd, wfd);
>@@ -225,11 +248,6 @@
> 
> 	/* XXX set close-on-exec -markus */
> 
>-	c->rfd = rfd;
>-	c->wfd = wfd;
>-	c->sock = (rfd == wfd) ? rfd : -1;
>-	c->ctl_fd = -1; /* XXX: set elsewhere */
>-	c->efd = efd;
> 	c->extended_usage = extusage;
> 
> 	/* XXX ugly hack: nonblock is only set by the server */
>@@ -403,6 +421,8 @@
> 		c->remote_name = NULL;
> 	}
> 	channels[c->self] = NULL;
>+	if (c->x11_fwd)
>+		x11_put_fwd(c->x11_fwd);
> 	xfree(c);
> }
> 
>@@ -826,6 +846,54 @@
> 		FD_SET(c->sock, writeset);
> }
> 
>+static struct x11_fwd *
>+x11_lookup_fwd_by_fakedata(unsigned char *proto, u_int protolen, unsigned char *data, u_int datalen)
>+{
>+	struct x11_fwd *fwd;
>+
>+	for (fwd = x11_fwds; fwd; fwd = fwd->next) {
>+		if (protolen == strlen(fwd->saved_proto) &&
>+		    !memcmp(fwd->saved_proto, proto, protolen) &&
>+		    fwd->fake_data_len == datalen &&
>+		    !memcmp(fwd->fake_data, data, datalen))
>+			break;
>+	}
>+	return fwd;
>+}
>+
>+static struct x11_fwd *
>+x11_lookup_fwd_by_realdata(const char *display, const char *proto, const u_char *authdata, u_int datalen)
>+{
>+	struct x11_fwd *fwd;
>+
>+	for (fwd = x11_fwds; fwd; fwd = fwd->next) {
>+		if (!strcmp(display, fwd->saved_display) &&
>+		    !strcmp(proto, fwd->saved_proto) &&
>+		    datalen == fwd->saved_data_len &&
>+		    !memcmp(authdata, fwd->saved_data, datalen))
>+			break;
>+	}
>+	return fwd;
>+}
>+
>+static void x11_put_fwd(struct x11_fwd *fwd)
>+{
>+	fwd->usecount--;
>+	debug("Decrease usecount on X11 forward data for %s to %d.", fwd->saved_display, fwd->usecount);
>+	if (!fwd->usecount) {
>+		struct x11_fwd **tmp = &x11_fwds;
>+		while (*tmp) {
>+			if (*tmp == fwd) {
>+				*tmp = fwd->next;
>+				xfree(fwd);
>+				return;
>+			}
>+			tmp = &(*tmp)->next;
>+		}
>+		fatal("X11 forward data not found.");
>+	}
>+}
>+
> /*
>  * This is a special state for X11 authentication spoofing.  An opened X11
>  * connection (when authentication spoofing is being done) remains in this
>@@ -836,10 +904,13 @@
>  * Returns: 0 = need more data, -1 = wrong cookie, 1 = ok
>  */
> static int
>-x11_open_helper(Buffer *b)
>+x11_open_helper(Channel *c)
> {
>+	Buffer *b = &c->output;
> 	u_char *ucp;
> 	u_int proto_len, data_len;
>+	struct x11_fwd *fwd;
>+	int sock;
> 
> 	/* Check if the fixed size part of the packet is in buffer. */
> 	if (buffer_len(b) < 12)
>@@ -864,50 +935,54 @@
> 	    12 + ((proto_len + 3) & ~3) + ((data_len + 3) & ~3))
> 		return 0;
> 
>-	/* Check if authentication protocol matches. */
>-	if (proto_len != strlen(x11_saved_proto) ||
>-	    memcmp(ucp + 12, x11_saved_proto, proto_len) != 0) {
>-		debug2("X11 connection uses different authentication protocol.");
>-		return -1;
>-	}
>-	/* Check if authentication data matches our fake data. */
>-	if (data_len != x11_fake_data_len ||
>-	    memcmp(ucp + 12 + ((proto_len + 3) & ~3),
>-		x11_fake_data, x11_fake_data_len) != 0) {
>-		debug2("X11 auth data does not match fake data.");
>-		return -1;
>-	}
>-	/* Check fake data length */
>-	if (x11_fake_data_len != x11_saved_data_len) {
>-		error("X11 fake_data_len %d != saved_data_len %d",
>-		    x11_fake_data_len, x11_saved_data_len);
>+	fwd = x11_lookup_fwd_by_fakedata(ucp+12, proto_len, 
>+		  ucp + 12 + ((proto_len + 3) & ~3), data_len);
>+
>+	if (!fwd) {
>+		debug("No matching X11 forward found.");
> 		return -1;
> 	}
>+	fwd->usecount++;
>+	debug("Increase use count for X11 fwd for display %s to %d.", fwd->saved_display, fwd->usecount);
>+	c->x11_fwd = fwd;
> 	/*
>-	 * Received authentication protocol and data match
>-	 * our fake data. Substitute the fake data with real
>-	 * data.
>+	 * We found a matching X11 forward. Substitute the fake data 
>+	 * with real data.
> 	 */
> 	memcpy(ucp + 12 + ((proto_len + 3) & ~3),
>-	    x11_saved_data, x11_saved_data_len);
>-	return 1;
>+	    fwd->saved_data, fwd->saved_data_len);
>+
>+	sock = x11_connect_display(fwd->saved_display);
>+	if (sock == -1)
>+		return -2;
>+	channel_register_fds(c, sock, sock, -1, 0, 1);
>+	c->type = SSH_CHANNEL_OPEN;
>+
>+	/* Because we registered a new fd, the channel_pre handlers will be
>+	   called again immediately. And because we changed the channel type
>+	   to SSH_CHANNEL_OPEN, the x11 function won't be called next time.
>+	   It's just a normal channel now */
>+	return 0;
> }
> 
> static void
> channel_pre_x11_open_13(Channel *c, fd_set *readset, fd_set *writeset)
> {
>-	int ret = x11_open_helper(&c->output);
>+	int ret = x11_open_helper(c);
> 
>-	if (ret == 1) {
>-		/* Start normal processing for the channel. */
>-		c->type = SSH_CHANNEL_OPEN;
>-		channel_pre_open_13(c, readset, writeset);
>-	} else if (ret == -1) {
>+	if (ret < 0) {
> 		/*
> 		 * We have received an X11 connection that has bad
> 		 * authentication information.
> 		 */
>-		logit("X11 connection rejected because of wrong authentication.");
>+		switch (ret) {
>+		case -1:
>+			logit("X11 connection rejected because of wrong authentication.");
>+			break;
>+		case -2:
>+			logit("X11 connection rejected due to failure to connect to local server.");
>+			break;
>+		}
> 		buffer_clear(&c->input);
> 		buffer_clear(&c->output);
> 		channel_close_fd(&c->sock);
>@@ -922,15 +997,17 @@
> static void
> channel_pre_x11_open(Channel *c, fd_set *readset, fd_set *writeset)
> {
>-	int ret = x11_open_helper(&c->output);
>-
>-	/* c->force_drain = 1; */
>+	int ret = x11_open_helper(c);
> 
>-	if (ret == 1) {
>-		c->type = SSH_CHANNEL_OPEN;
>-		channel_pre_open(c, readset, writeset);
>-	} else if (ret == -1) {
>-		logit("X11 connection rejected because of wrong authentication.");
>+	if (ret < 0) {
>+		switch (ret) {
>+		case -1:
>+			logit("X11 connection rejected because of wrong authentication.");
>+			break;
>+		case -2:
>+			logit("X11 connection rejected due to failure to connect to local server.");
>+			break;
>+		}
> 		debug2("X11 rejected %d i%d/o%d", c->self, c->istate, c->ostate);
> 		chan_read_failed(c);
> 		buffer_clear(&c->input);
>@@ -1834,26 +1911,30 @@
> {
> 	u_int n, sz, nfdset;
> 
>-	n = MAX(*maxfdp, channel_max_fd);
>+	for (channel_fds_changed = 1; channel_fds_changed;) {
>+		channel_fds_changed = 0;
>+		n = MAX(*maxfdp, channel_max_fd);
>+
>+		nfdset = howmany(n+1, NFDBITS);
>+		/* Explicitly test here, because xrealloc isn't always called */
>+		if (nfdset && SIZE_T_MAX / nfdset < sizeof(fd_mask))
>+			fatal("channel_prepare_select: max_fd (%d) is too large", n);
>+		sz = nfdset * sizeof(fd_mask);
>+
>+		/* perhaps check sz < nalloc/2 and shrink? */
>+		if (*readsetp == NULL || sz > *nallocp) {
>+			*readsetp = xrealloc(*readsetp, nfdset, sizeof(fd_mask));
>+			*writesetp = xrealloc(*writesetp, nfdset, sizeof(fd_mask));
>+			*nallocp = sz;
>+		}
>+		*maxfdp = n;
>+		memset(*readsetp, 0, sz);
>+		memset(*writesetp, 0, sz);
> 
>-	nfdset = howmany(n+1, NFDBITS);
>-	/* Explicitly test here, because xrealloc isn't always called */
>-	if (nfdset && SIZE_T_MAX / nfdset < sizeof(fd_mask))
>-		fatal("channel_prepare_select: max_fd (%d) is too large", n);
>-	sz = nfdset * sizeof(fd_mask);
>-
>-	/* perhaps check sz < nalloc/2 and shrink? */
>-	if (*readsetp == NULL || sz > *nallocp) {
>-		*readsetp = xrealloc(*readsetp, nfdset, sizeof(fd_mask));
>-		*writesetp = xrealloc(*writesetp, nfdset, sizeof(fd_mask));
>-		*nallocp = sz;
>-	}
>-	*maxfdp = n;
>-	memset(*readsetp, 0, sz);
>-	memset(*writesetp, 0, sz);
>+		if (!rekeying)
>+			channel_handler(channel_pre, *readsetp, *writesetp);
>+	}
> 
>-	if (!rekeying)
>-		channel_handler(channel_pre, *readsetp, *writesetp);
> }
> 
> /*
>@@ -2973,23 +3054,16 @@
> }
> 
> int
>-x11_connect_display(void)
>+x11_connect_display(char *display)
> {
> 	u_int display_number;
>-	const char *display;
> 	char buf[1024], *cp;
> 	struct addrinfo hints, *ai, *aitop;
> 	char strport[NI_MAXSERV];
> 	int gaierr, sock = 0;
> 
>-	/* Try to open a socket for the local X server. */
>-	display = getenv("DISPLAY");
>-	if (!display) {
>-		error("DISPLAY not set.");
>-		return -1;
>-	}
> 	/*
>-	 * Now we decode the value of the DISPLAY variable and make a
>+	 * Decode the value of the DISPLAY variable and make a
> 	 * connection to the real X server.
> 	 */
> 
>@@ -3078,7 +3152,7 @@
> x11_input_open(int type, u_int32_t seq, void *ctxt)
> {
> 	Channel *c = NULL;
>-	int remote_id, sock = 0;
>+	int remote_id;
> 	char *remote_host;
> 
> 	debug("Received X11 open request.");
>@@ -3092,27 +3166,20 @@
> 	}
> 	packet_check_eom();
> 
>-	/* Obtain a connection to the real X display. */
>-	sock = x11_connect_display();
>-	if (sock != -1) {
>-		/* Allocate a channel for this connection. */
>-		c = channel_new("connected x11 socket",
>-		    SSH_CHANNEL_X11_OPEN, sock, sock, -1, 0, 0, 0,
>-		    remote_host, 1);
>-		c->remote_id = remote_id;
>-		c->force_drain = 1;
>-	}
>+	/* Allocate a channel for this connection. */
>+	c = channel_new("connected x11 socket",
>+	    SSH_CHANNEL_X11_OPEN, -1, -1, -1, 0, 0, 0,
>+	    remote_host, 1);
>+	c->remote_id = remote_id;
>+	c->force_drain = 1;
>+
> 	xfree(remote_host);
>-	if (c == NULL) {
>-		/* Send refusal to the remote host. */
>-		packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
>-		packet_put_int(remote_id);
>-	} else {
>-		/* Send a confirmation to the remote host. */
>-		packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
>-		packet_put_int(remote_id);
>-		packet_put_int(c->self);
>-	}
>+
>+	/* Send a confirmation to the remote host. */
>+	packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
>+	packet_put_int(remote_id);
>+	packet_put_int(c->self);
>+
> 	packet_send();
> }
> 
>@@ -3149,21 +3216,62 @@
> x11_request_forwarding_with_spoofing(int client_session_id, const char *disp,
>     const char *proto, const char *data)
> {
>+	Channel *c = NULL;
> 	u_int data_len = (u_int) strlen(data) / 2;
> 	u_int i, value;
> 	char *new_data;
>+	u_char *realdata;
> 	int screen_number;
> 	const char *cp;
> 	u_int32_t rnd = 0;
>+	struct x11_fwd *fwd;
> 
>-	if (x11_saved_display == NULL)
>-		x11_saved_display = xstrdup(disp);
>-	else if (strcmp(disp, x11_saved_display) != 0) {
>-		error("x11_request_forwarding_with_spoofing: different "
>-		    "$DISPLAY already forwarded");
>-		return;
>+	if (compat20) {
>+		c = channel_lookup(client_session_id);
>+		if (!c)
>+			error("%s: channel %d: unknown channel", __func__, client_session_id);
>+	}
>+		
>+	/* Convert real authentication data to binary */
>+	realdata = xmalloc(data_len);
>+	for (i = 0; i < data_len; i++) {
>+		if (sscanf(data + 2 * i, "%2x", &value) != 1)
>+			fatal("x11_request_forwarding: bad "
>+			    "authentication data: %.100s", data);
>+		realdata[i] = value;
>+	}
>+
>+	fwd = x11_lookup_fwd_by_realdata(disp, proto, realdata, data_len);
>+	if (fwd) {
>+		fwd->usecount++;
>+		debug("Increase use count for X11 fwd for display %s to %d.", disp, fwd->usecount);
>+		xfree(realdata);
>+	} else {
>+		/* No existing forward. Create a new one */
>+		debug("Create new X11 fake auth data for display %s.", disp);
>+		fwd = xmalloc(sizeof(*fwd));
>+		fwd->saved_display = xstrdup(disp);
>+		fwd->saved_proto = xstrdup(proto);
>+		fwd->saved_data = realdata;
>+		fwd->saved_data_len = data_len;
>+		fwd->fake_data = xmalloc(data_len);
>+		fwd->fake_data_len = data_len;
>+
>+		for (i = 0; i < data_len; i++) {
>+			if (i % 4 == 0)
>+				rnd = arc4random();
>+			fwd->fake_data[i] = rnd & 0xff;
>+			rnd >>= 8;
>+		}
>+
>+		fwd->usecount = 1;
>+		fwd->next = x11_fwds;
>+		x11_fwds = fwd;
> 	}
> 
>+	if (c)
>+		c->x11_fwd = fwd;
>+		
> 	cp = strchr(disp, ':');
> 	if (cp)
> 		cp = strchr(cp, '.');
>@@ -3172,31 +3280,8 @@
> 	else
> 		screen_number = 0;
> 
>-	if (x11_saved_proto == NULL) {
>-		/* Save protocol name. */
>-		x11_saved_proto = xstrdup(proto);
>-		/*
>-		 * Extract real authentication data and generate fake data
>-		 * of the same length.
>-		 */
>-		x11_saved_data = xmalloc(data_len);
>-		x11_fake_data = xmalloc(data_len);
>-		for (i = 0; i < data_len; i++) {
>-			if (sscanf(data + 2 * i, "%2x", &value) != 1)
>-				fatal("x11_request_forwarding: bad "
>-				    "authentication data: %.100s", data);
>-			if (i % 4 == 0)
>-				rnd = arc4random();
>-			x11_saved_data[i] = value;
>-			x11_fake_data[i] = rnd & 0xff;
>-			rnd >>= 8;
>-		}
>-		x11_saved_data_len = data_len;
>-		x11_fake_data_len = data_len;
>-	}
>-
> 	/* Convert the fake data into hex. */
>-	new_data = tohex(x11_fake_data, data_len);
>+	new_data = tohex(fwd->fake_data, data_len);
> 
> 	/* Send the request packet. */
> 	if (compat20) {
>diff -ur openssh-4.5p1/channels.h openssh-4.5p1-multidisplay/channels.h
>--- openssh-4.5p1/channels.h	2006-08-05 03:39:39.000000000 +0100
>+++ openssh-4.5p1-multidisplay/channels.h	2007-03-24 16:18:19.000000000 +0000
>@@ -57,6 +57,7 @@
> 
> #define SSH_CHANNEL_PATH_LEN		256
> 
>+struct x11_fwd;
> struct Channel;
> typedef struct Channel Channel;
> 
>@@ -114,6 +115,9 @@
> 	channel_outfilter_fn	*output_filter;
> 
> 	int     datagram;	/* keep boundaries */
>+
>+	/* X11 forwarding data */
>+	struct x11_fwd		*x11_fwd;
> };
> 
> #define CHAN_EXTENDED_IGNORE		0
>@@ -221,7 +225,7 @@
> 
> /* x11 forwarding */
> 
>-int	 x11_connect_display(void);
>+int	 x11_connect_display(char *);
> int	 x11_create_display_inet(int, int, int, u_int *, int **);
> void     x11_input_open(int, u_int32_t, void *);
> void	 x11_request_forwarding_with_spoofing(int, const char *, const char *,
>Only in openssh-4.5p1: cipher.c.orig
>diff -ur openssh-4.5p1/clientloop.c openssh-4.5p1-multidisplay/clientloop.c
>--- openssh-4.5p1/clientloop.c	2006-10-23 18:02:41.000000000 +0100
>+++ openssh-4.5p1-multidisplay/clientloop.c	2007-03-24 16:18:19.000000000 +0000
>@@ -1736,11 +1736,8 @@
> 	debug("client_request_x11: request from %s %d", originator,
> 	    originator_port);
> 	xfree(originator);
>-	sock = x11_connect_display();
>-	if (sock < 0)
>-		return NULL;
> 	c = channel_new("x11",
>-	    SSH_CHANNEL_X11_OPEN, sock, sock, -1,
>+	    SSH_CHANNEL_X11_OPEN, -1, -1, -1,
> 	    CHAN_TCP_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT, 0, "x11", 1);
> 	c->force_drain = 1;
> 	return c;

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Attachments on bug 1328: 1316 | 1317 | 1856 | 1857