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-rw-r--r--tools/plink/x11fwd.c1884
1 files changed, 1088 insertions, 796 deletions
diff --git a/tools/plink/x11fwd.c b/tools/plink/x11fwd.c
index d98908a77..7ecb4cc27 100644
--- a/tools/plink/x11fwd.c
+++ b/tools/plink/x11fwd.c
@@ -1,796 +1,1088 @@
-/*
- * Platform-independent bits of X11 forwarding.
- */
-
-#include <stdio.h>
-#include <stdlib.h>
-#include <assert.h>
-#include <time.h>
-
-#include "putty.h"
-#include "ssh.h"
-#include "tree234.h"
-
-#define GET_16BIT(endian, cp) \
- (endian=='B' ? GET_16BIT_MSB_FIRST(cp) : GET_16BIT_LSB_FIRST(cp))
-
-#define PUT_16BIT(endian, cp, val) \
- (endian=='B' ? PUT_16BIT_MSB_FIRST(cp, val) : PUT_16BIT_LSB_FIRST(cp, val))
-
-const char *const x11_authnames[] = {
- "", "MIT-MAGIC-COOKIE-1", "XDM-AUTHORIZATION-1"
-};
-
-struct XDMSeen {
- unsigned int time;
- unsigned char clientid[6];
-};
-
-struct X11Private {
- const struct plug_function_table *fn;
- /* the above variable absolutely *must* be the first in this structure */
- unsigned char firstpkt[12]; /* first X data packet */
- struct X11Display *disp;
- char *auth_protocol;
- unsigned char *auth_data;
- int data_read, auth_plen, auth_psize, auth_dlen, auth_dsize;
- int verified;
- int throttled, throttle_override;
- unsigned long peer_ip;
- int peer_port;
- void *c; /* data used by ssh.c */
- Socket s;
-};
-
-static int xdmseen_cmp(void *a, void *b)
-{
- struct XDMSeen *sa = a, *sb = b;
- return sa->time > sb->time ? 1 :
- sa->time < sb->time ? -1 :
- memcmp(sa->clientid, sb->clientid, sizeof(sa->clientid));
-}
-
-/* Do-nothing "plug" implementation, used by x11_setup_display() when it
- * creates a trial connection (and then immediately closes it).
- * XXX: bit out of place here, could in principle live in a platform-
- * independent network.c or something */
-static void dummy_plug_log(Plug p, int type, SockAddr addr, int port,
- const char *error_msg, int error_code) { }
-static int dummy_plug_closing
- (Plug p, const char *error_msg, int error_code, int calling_back)
-{ return 1; }
-static int dummy_plug_receive(Plug p, int urgent, char *data, int len)
-{ return 1; }
-static void dummy_plug_sent(Plug p, int bufsize) { }
-static int dummy_plug_accepting(Plug p, OSSocket sock) { return 1; }
-static const struct plug_function_table dummy_plug = {
- dummy_plug_log, dummy_plug_closing, dummy_plug_receive,
- dummy_plug_sent, dummy_plug_accepting
-};
-
-struct X11Display *x11_setup_display(char *display, int authtype, Conf *conf)
-{
- struct X11Display *disp = snew(struct X11Display);
- char *localcopy;
- int i;
-
- if (!display || !*display) {
- localcopy = platform_get_x_display();
- if (!localcopy || !*localcopy) {
- sfree(localcopy);
- localcopy = dupstr(":0"); /* plausible default for any platform */
- }
- } else
- localcopy = dupstr(display);
-
- /*
- * Parse the display name.
- *
- * We expect this to have one of the following forms:
- *
- * - the standard X format which looks like
- * [ [ protocol '/' ] host ] ':' displaynumber [ '.' screennumber ]
- * (X11 also permits a double colon to indicate DECnet, but
- * that's not our problem, thankfully!)
- *
- * - only seen in the wild on MacOS (so far): a pathname to a
- * Unix-domain socket, which will typically and confusingly
- * end in ":0", and which I'm currently distinguishing from
- * the standard scheme by noting that it starts with '/'.
- */
- if (localcopy[0] == '/') {
- disp->unixsocketpath = localcopy;
- disp->unixdomain = TRUE;
- disp->hostname = NULL;
- disp->displaynum = -1;
- disp->screennum = 0;
- disp->addr = NULL;
- } else {
- char *colon, *dot, *slash;
- char *protocol, *hostname;
-
- colon = strrchr(localcopy, ':');
- if (!colon) {
- sfree(disp);
- sfree(localcopy);
- return NULL; /* FIXME: report a specific error? */
- }
-
- *colon++ = '\0';
- dot = strchr(colon, '.');
- if (dot)
- *dot++ = '\0';
-
- disp->displaynum = atoi(colon);
- if (dot)
- disp->screennum = atoi(dot);
- else
- disp->screennum = 0;
-
- protocol = NULL;
- hostname = localcopy;
- if (colon > localcopy) {
- slash = strchr(localcopy, '/');
- if (slash) {
- *slash++ = '\0';
- protocol = localcopy;
- hostname = slash;
- }
- }
-
- disp->hostname = *hostname ? dupstr(hostname) : NULL;
-
- if (protocol)
- disp->unixdomain = (!strcmp(protocol, "local") ||
- !strcmp(protocol, "unix"));
- else if (!*hostname || !strcmp(hostname, "unix"))
- disp->unixdomain = platform_uses_x11_unix_by_default;
- else
- disp->unixdomain = FALSE;
-
- if (!disp->hostname && !disp->unixdomain)
- disp->hostname = dupstr("localhost");
-
- disp->unixsocketpath = NULL;
- disp->addr = NULL;
-
- sfree(localcopy);
- }
-
- /*
- * Look up the display hostname, if we need to.
- */
- if (!disp->unixdomain) {
- const char *err;
-
- disp->port = 6000 + disp->displaynum;
- disp->addr = name_lookup(disp->hostname, disp->port,
- &disp->realhost, conf, ADDRTYPE_UNSPEC);
-
- if ((err = sk_addr_error(disp->addr)) != NULL) {
- sk_addr_free(disp->addr);
- sfree(disp->hostname);
- sfree(disp->unixsocketpath);
- return NULL; /* FIXME: report an error */
- }
- }
-
- /*
- * Try upgrading an IP-style localhost display to a Unix-socket
- * display (as the standard X connection libraries do).
- */
- if (!disp->unixdomain && sk_address_is_local(disp->addr)) {
- SockAddr ux = platform_get_x11_unix_address(NULL, disp->displaynum);
- const char *err = sk_addr_error(ux);
- if (!err) {
- /* Create trial connection to see if there is a useful Unix-domain
- * socket */
- const struct plug_function_table *dummy = &dummy_plug;
- Socket s = sk_new(sk_addr_dup(ux), 0, 0, 0, 0, 0, (Plug)&dummy);
- err = sk_socket_error(s);
- sk_close(s);
- }
- if (err) {
- sk_addr_free(ux);
- } else {
- sk_addr_free(disp->addr);
- disp->unixdomain = TRUE;
- disp->addr = ux;
- /* Fill in the rest in a moment */
- }
- }
-
- if (disp->unixdomain) {
- if (!disp->addr)
- disp->addr = platform_get_x11_unix_address(disp->unixsocketpath,
- disp->displaynum);
- if (disp->unixsocketpath)
- disp->realhost = dupstr(disp->unixsocketpath);
- else
- disp->realhost = dupprintf("unix:%d", disp->displaynum);
- disp->port = 0;
- }
-
- /*
- * Invent the remote authorisation details.
- */
- if (authtype == X11_MIT) {
- disp->remoteauthproto = X11_MIT;
-
- /* MIT-MAGIC-COOKIE-1. Cookie size is 128 bits (16 bytes). */
- disp->remoteauthdata = snewn(16, unsigned char);
- for (i = 0; i < 16; i++)
- disp->remoteauthdata[i] = random_byte();
- disp->remoteauthdatalen = 16;
-
- disp->xdmseen = NULL;
- } else {
- assert(authtype == X11_XDM);
- disp->remoteauthproto = X11_XDM;
-
- /* XDM-AUTHORIZATION-1. Cookie size is 16 bytes; byte 8 is zero. */
- disp->remoteauthdata = snewn(16, unsigned char);
- for (i = 0; i < 16; i++)
- disp->remoteauthdata[i] = (i == 8 ? 0 : random_byte());
- disp->remoteauthdatalen = 16;
-
- disp->xdmseen = newtree234(xdmseen_cmp);
- }
- disp->remoteauthprotoname = dupstr(x11_authnames[disp->remoteauthproto]);
- disp->remoteauthdatastring = snewn(disp->remoteauthdatalen * 2 + 1, char);
- for (i = 0; i < disp->remoteauthdatalen; i++)
- sprintf(disp->remoteauthdatastring + i*2, "%02x",
- disp->remoteauthdata[i]);
-
- /*
- * Fetch the local authorisation details.
- */
- disp->localauthproto = X11_NO_AUTH;
- disp->localauthdata = NULL;
- disp->localauthdatalen = 0;
- platform_get_x11_auth(disp, conf);
-
- return disp;
-}
-
-void x11_free_display(struct X11Display *disp)
-{
- if (disp->xdmseen != NULL) {
- struct XDMSeen *seen;
- while ((seen = delpos234(disp->xdmseen, 0)) != NULL)
- sfree(seen);
- freetree234(disp->xdmseen);
- }
- sfree(disp->hostname);
- sfree(disp->unixsocketpath);
- if (disp->localauthdata)
- memset(disp->localauthdata, 0, disp->localauthdatalen);
- sfree(disp->localauthdata);
- if (disp->remoteauthdata)
- memset(disp->remoteauthdata, 0, disp->remoteauthdatalen);
- sfree(disp->remoteauthdata);
- sfree(disp->remoteauthprotoname);
- sfree(disp->remoteauthdatastring);
- sk_addr_free(disp->addr);
- sfree(disp);
-}
-
-#define XDM_MAXSKEW 20*60 /* 20 minute clock skew should be OK */
-
-static char *x11_verify(unsigned long peer_ip, int peer_port,
- struct X11Display *disp, char *proto,
- unsigned char *data, int dlen)
-{
- if (strcmp(proto, x11_authnames[disp->remoteauthproto]) != 0)
- return "wrong authorisation protocol attempted";
- if (disp->remoteauthproto == X11_MIT) {
- if (dlen != disp->remoteauthdatalen)
- return "MIT-MAGIC-COOKIE-1 data was wrong length";
- if (memcmp(disp->remoteauthdata, data, dlen) != 0)
- return "MIT-MAGIC-COOKIE-1 data did not match";
- }
- if (disp->remoteauthproto == X11_XDM) {
- unsigned long t;
- time_t tim;
- int i;
- struct XDMSeen *seen, *ret;
-
- if (dlen != 24)
- return "XDM-AUTHORIZATION-1 data was wrong length";
- if (peer_port == -1)
- return "cannot do XDM-AUTHORIZATION-1 without remote address data";
- des_decrypt_xdmauth(disp->remoteauthdata+9, data, 24);
- if (memcmp(disp->remoteauthdata, data, 8) != 0)
- return "XDM-AUTHORIZATION-1 data failed check"; /* cookie wrong */
- if (GET_32BIT_MSB_FIRST(data+8) != peer_ip)
- return "XDM-AUTHORIZATION-1 data failed check"; /* IP wrong */
- if ((int)GET_16BIT_MSB_FIRST(data+12) != peer_port)
- return "XDM-AUTHORIZATION-1 data failed check"; /* port wrong */
- t = GET_32BIT_MSB_FIRST(data+14);
- for (i = 18; i < 24; i++)
- if (data[i] != 0) /* zero padding wrong */
- return "XDM-AUTHORIZATION-1 data failed check";
- tim = time(NULL);
- if (abs(t - tim) > XDM_MAXSKEW)
- return "XDM-AUTHORIZATION-1 time stamp was too far out";
- seen = snew(struct XDMSeen);
- seen->time = t;
- memcpy(seen->clientid, data+8, 6);
- assert(disp->xdmseen != NULL);
- ret = add234(disp->xdmseen, seen);
- if (ret != seen) {
- sfree(seen);
- return "XDM-AUTHORIZATION-1 data replayed";
- }
- /* While we're here, purge entries too old to be replayed. */
- for (;;) {
- seen = index234(disp->xdmseen, 0);
- assert(seen != NULL);
- if (t - seen->time <= XDM_MAXSKEW)
- break;
- sfree(delpos234(disp->xdmseen, 0));
- }
- }
- /* implement other protocols here if ever required */
- return NULL;
-}
-
-void x11_get_auth_from_authfile(struct X11Display *disp,
- const char *authfilename)
-{
- FILE *authfp;
- char *buf, *ptr, *str[4];
- int len[4];
- int family, protocol;
- int ideal_match = FALSE;
- char *ourhostname = get_hostname();
-
- /*
- * Normally we should look for precisely the details specified in
- * `disp'. However, there's an oddity when the display is local:
- * displays like "localhost:0" usually have their details stored
- * in a Unix-domain-socket record (even if there isn't actually a
- * real Unix-domain socket available, as with OpenSSH's proxy X11
- * server).
- *
- * This is apparently a fudge to get round the meaninglessness of
- * "localhost" in a shared-home-directory context -- xauth entries
- * for Unix-domain sockets already disambiguate this by storing
- * the *local* hostname in the conveniently-blank hostname field,
- * but IP "localhost" records couldn't do this. So, typically, an
- * IP "localhost" entry in the auth database isn't present and if
- * it were it would be ignored.
- *
- * However, we don't entirely trust that (say) Windows X servers
- * won't rely on a straight "localhost" entry, bad idea though
- * that is; so if we can't find a Unix-domain-socket entry we'll
- * fall back to an IP-based entry if we can find one.
- */
- int localhost = !disp->unixdomain && sk_address_is_local(disp->addr);
-
- authfp = fopen(authfilename, "rb");
- if (!authfp)
- return;
-
- /* Records in .Xauthority contain four strings of up to 64K each */
- buf = snewn(65537 * 4, char);
-
- while (!ideal_match) {
- int c, i, j, match = FALSE;
-
-#define GET do { c = fgetc(authfp); if (c == EOF) goto done; c = (unsigned char)c; } while (0)
- /* Expect a big-endian 2-byte number giving address family */
- GET; family = c;
- GET; family = (family << 8) | c;
- /* Then expect four strings, each composed of a big-endian 2-byte
- * length field followed by that many bytes of data */
- ptr = buf;
- for (i = 0; i < 4; i++) {
- GET; len[i] = c;
- GET; len[i] = (len[i] << 8) | c;
- str[i] = ptr;
- for (j = 0; j < len[i]; j++) {
- GET; *ptr++ = c;
- }
- *ptr++ = '\0';
- }
-#undef GET
-
- /*
- * Now we have a full X authority record in memory. See
- * whether it matches the display we're trying to
- * authenticate to.
- *
- * The details we've just read should be interpreted as
- * follows:
- *
- * - 'family' is the network address family used to
- * connect to the display. 0 means IPv4; 6 means IPv6;
- * 256 means Unix-domain sockets.
- *
- * - str[0] is the network address itself. For IPv4 and
- * IPv6, this is a string of binary data of the
- * appropriate length (respectively 4 and 16 bytes)
- * representing the address in big-endian format, e.g.
- * 7F 00 00 01 means IPv4 localhost. For Unix-domain
- * sockets, this is the host name of the machine on
- * which the Unix-domain display resides (so that an
- * .Xauthority file on a shared file system can contain
- * authority entries for Unix-domain displays on
- * several machines without them clashing).
- *
- * - str[1] is the display number. I've no idea why
- * .Xauthority stores this as a string when it has a
- * perfectly good integer format, but there we go.
- *
- * - str[2] is the authorisation method, encoded as its
- * canonical string name (i.e. "MIT-MAGIC-COOKIE-1",
- * "XDM-AUTHORIZATION-1" or something we don't
- * recognise).
- *
- * - str[3] is the actual authorisation data, stored in
- * binary form.
- */
-
- if (disp->displaynum < 0 || disp->displaynum != atoi(str[1]))
- continue; /* not the one */
-
- for (protocol = 1; protocol < lenof(x11_authnames); protocol++)
- if (!strcmp(str[2], x11_authnames[protocol]))
- break;
- if (protocol == lenof(x11_authnames))
- continue; /* don't recognise this protocol, look for another */
-
- switch (family) {
- case 0: /* IPv4 */
- if (!disp->unixdomain &&
- sk_addrtype(disp->addr) == ADDRTYPE_IPV4) {
- char buf[4];
- sk_addrcopy(disp->addr, buf);
- if (len[0] == 4 && !memcmp(str[0], buf, 4)) {
- match = TRUE;
- /* If this is a "localhost" entry, note it down
- * but carry on looking for a Unix-domain entry. */
- ideal_match = !localhost;
- }
- }
- break;
- case 6: /* IPv6 */
- if (!disp->unixdomain &&
- sk_addrtype(disp->addr) == ADDRTYPE_IPV6) {
- char buf[16];
- sk_addrcopy(disp->addr, buf);
- if (len[0] == 16 && !memcmp(str[0], buf, 16)) {
- match = TRUE;
- ideal_match = !localhost;
- }
- }
- break;
- case 256: /* Unix-domain / localhost */
- if ((disp->unixdomain || localhost)
- && ourhostname && !strcmp(ourhostname, str[0]))
- /* A matching Unix-domain socket is always the best
- * match. */
- match = ideal_match = TRUE;
- break;
- }
-
- if (match) {
- /* Current best guess -- may be overridden if !ideal_match */
- disp->localauthproto = protocol;
- sfree(disp->localauthdata); /* free previous guess, if any */
- disp->localauthdata = snewn(len[3], unsigned char);
- memcpy(disp->localauthdata, str[3], len[3]);
- disp->localauthdatalen = len[3];
- }
- }
-
- done:
- fclose(authfp);
- memset(buf, 0, 65537 * 4);
- sfree(buf);
- sfree(ourhostname);
-}
-
-static void x11_log(Plug p, int type, SockAddr addr, int port,
- const char *error_msg, int error_code)
-{
- /* We have no interface to the logging module here, so we drop these. */
-}
-
-static int x11_closing(Plug plug, const char *error_msg, int error_code,
- int calling_back)
-{
- struct X11Private *pr = (struct X11Private *) plug;
-
- /*
- * We have no way to communicate down the forwarded connection,
- * so if an error occurred on the socket, we just ignore it
- * and treat it like a proper close.
- *
- * FIXME: except we could initiate a full close here instead of
- * just an outgoing EOF? ssh.c currently has no API for that, but
- * it could.
- */
- sshfwd_write_eof(pr->c);
- return 1;
-}
-
-static int x11_receive(Plug plug, int urgent, char *data, int len)
-{
- struct X11Private *pr = (struct X11Private *) plug;
-
- if (sshfwd_write(pr->c, data, len) > 0) {
- pr->throttled = 1;
- sk_set_frozen(pr->s, 1);
- }
-
- return 1;
-}
-
-static void x11_sent(Plug plug, int bufsize)
-{
- struct X11Private *pr = (struct X11Private *) plug;
-
- sshfwd_unthrottle(pr->c, bufsize);
-}
-
-/*
- * When setting up X forwarding, we should send the screen number
- * from the specified local display. This function extracts it from
- * the display string.
- */
-int x11_get_screen_number(char *display)
-{
- int n;
-
- n = strcspn(display, ":");
- if (!display[n])
- return 0;
- n = strcspn(display, ".");
- if (!display[n])
- return 0;
- return atoi(display + n + 1);
-}
-
-/*
- * Called to set up the raw connection.
- *
- * Returns an error message, or NULL on success.
- * also, fills the SocketsStructure
- */
-extern const char *x11_init(Socket *s, struct X11Display *disp, void *c,
- const char *peeraddr, int peerport, Conf *conf)
-{
- static const struct plug_function_table fn_table = {
- x11_log,
- x11_closing,
- x11_receive,
- x11_sent,
- NULL
- };
-
- const char *err;
- struct X11Private *pr;
-
- /*
- * Open socket.
- */
- pr = snew(struct X11Private);
- pr->fn = &fn_table;
- pr->auth_protocol = NULL;
- pr->disp = disp;
- pr->verified = 0;
- pr->data_read = 0;
- pr->throttled = pr->throttle_override = 0;
- pr->c = c;
-
- pr->s = *s = new_connection(sk_addr_dup(disp->addr),
- disp->realhost, disp->port,
- 0, 1, 0, 0, (Plug) pr, conf);
- if ((err = sk_socket_error(*s)) != NULL) {
- sfree(pr);
- return err;
- }
-
- /*
- * See if we can make sense of the peer address we were given.
- */
- {
- int i[4];
- if (peeraddr &&
- 4 == sscanf(peeraddr, "%d.%d.%d.%d", i+0, i+1, i+2, i+3)) {
- pr->peer_ip = (i[0] << 24) | (i[1] << 16) | (i[2] << 8) | i[3];
- pr->peer_port = peerport;
- } else {
- pr->peer_ip = 0;
- pr->peer_port = -1;
- }
- }
-
- sk_set_private_ptr(*s, pr);
- return NULL;
-}
-
-void x11_close(Socket s)
-{
- struct X11Private *pr;
- if (!s)
- return;
- pr = (struct X11Private *) sk_get_private_ptr(s);
- if (pr->auth_protocol) {
- sfree(pr->auth_protocol);
- sfree(pr->auth_data);
- }
-
- sfree(pr);
-
- sk_close(s);
-}
-
-void x11_unthrottle(Socket s)
-{
- struct X11Private *pr;
- if (!s)
- return;
- pr = (struct X11Private *) sk_get_private_ptr(s);
-
- pr->throttled = 0;
- sk_set_frozen(s, pr->throttled || pr->throttle_override);
-}
-
-void x11_override_throttle(Socket s, int enable)
-{
- struct X11Private *pr;
- if (!s)
- return;
- pr = (struct X11Private *) sk_get_private_ptr(s);
-
- pr->throttle_override = enable;
- sk_set_frozen(s, pr->throttled || pr->throttle_override);
-}
-
-/*
- * Called to send data down the raw connection.
- */
-int x11_send(Socket s, char *data, int len)
-{
- struct X11Private *pr;
- if (!s)
- return 0;
- pr = (struct X11Private *) sk_get_private_ptr(s);
-
- /*
- * Read the first packet.
- */
- while (len > 0 && pr->data_read < 12)
- pr->firstpkt[pr->data_read++] = (unsigned char) (len--, *data++);
- if (pr->data_read < 12)
- return 0;
-
- /*
- * If we have not allocated the auth_protocol and auth_data
- * strings, do so now.
- */
- if (!pr->auth_protocol) {
- pr->auth_plen = GET_16BIT(pr->firstpkt[0], pr->firstpkt + 6);
- pr->auth_dlen = GET_16BIT(pr->firstpkt[0], pr->firstpkt + 8);
- pr->auth_psize = (pr->auth_plen + 3) & ~3;
- pr->auth_dsize = (pr->auth_dlen + 3) & ~3;
- /* Leave room for a terminating zero, to make our lives easier. */
- pr->auth_protocol = snewn(pr->auth_psize + 1, char);
- pr->auth_data = snewn(pr->auth_dsize, unsigned char);
- }
-
- /*
- * Read the auth_protocol and auth_data strings.
- */
- while (len > 0 && pr->data_read < 12 + pr->auth_psize)
- pr->auth_protocol[pr->data_read++ - 12] = (len--, *data++);
- while (len > 0 && pr->data_read < 12 + pr->auth_psize + pr->auth_dsize)
- pr->auth_data[pr->data_read++ - 12 -
- pr->auth_psize] = (unsigned char) (len--, *data++);
- if (pr->data_read < 12 + pr->auth_psize + pr->auth_dsize)
- return 0;
-
- /*
- * If we haven't verified the authorisation, do so now.
- */
- if (!pr->verified) {
- char *err;
-
- pr->auth_protocol[pr->auth_plen] = '\0'; /* ASCIZ */
- err = x11_verify(pr->peer_ip, pr->peer_port,
- pr->disp, pr->auth_protocol,
- pr->auth_data, pr->auth_dlen);
-
- /*
- * If authorisation failed, construct and send an error
- * packet, then terminate the connection.
- */
- if (err) {
- char *message;
- int msglen, msgsize;
- unsigned char *reply;
-
- message = dupprintf("%s X11 proxy: %s", appname, err);
- msglen = strlen(message);
- reply = snewn(8 + msglen+1 + 4, unsigned char); /* include zero */
- msgsize = (msglen + 3) & ~3;
- reply[0] = 0; /* failure */
- reply[1] = msglen; /* length of reason string */
- memcpy(reply + 2, pr->firstpkt + 2, 4); /* major/minor proto vsn */
- PUT_16BIT(pr->firstpkt[0], reply + 6, msgsize >> 2);/* data len */
- memset(reply + 8, 0, msgsize);
- memcpy(reply + 8, message, msglen);
- sshfwd_write(pr->c, (char *)reply, 8 + msgsize);
- sshfwd_write_eof(pr->c);
- sfree(reply);
- sfree(message);
- return 0;
- }
-
- /*
- * Now we know we're going to accept the connection. Strip
- * the fake auth data, and optionally put real auth data in
- * instead.
- */
- {
- char realauthdata[64];
- int realauthlen = 0;
- int authstrlen = strlen(x11_authnames[pr->disp->localauthproto]);
- int buflen = 0; /* initialise to placate optimiser */
- static const char zeroes[4] = { 0,0,0,0 };
- void *buf;
-
- if (pr->disp->localauthproto == X11_MIT) {
- assert(pr->disp->localauthdatalen <= lenof(realauthdata));
- realauthlen = pr->disp->localauthdatalen;
- memcpy(realauthdata, pr->disp->localauthdata, realauthlen);
- } else if (pr->disp->localauthproto == X11_XDM &&
- pr->disp->localauthdatalen == 16 &&
- ((buf = sk_getxdmdata(s, &buflen))!=0)) {
- time_t t;
- realauthlen = (buflen+12+7) & ~7;
- assert(realauthlen <= lenof(realauthdata));
- memset(realauthdata, 0, realauthlen);
- memcpy(realauthdata, pr->disp->localauthdata, 8);
- memcpy(realauthdata+8, buf, buflen);
- t = time(NULL);
- PUT_32BIT_MSB_FIRST(realauthdata+8+buflen, t);
- des_encrypt_xdmauth(pr->disp->localauthdata+9,
- (unsigned char *)realauthdata,
- realauthlen);
- sfree(buf);
- }
- /* implement other auth methods here if required */
-
- PUT_16BIT(pr->firstpkt[0], pr->firstpkt + 6, authstrlen);
- PUT_16BIT(pr->firstpkt[0], pr->firstpkt + 8, realauthlen);
-
- sk_write(s, (char *)pr->firstpkt, 12);
-
- if (authstrlen) {
- sk_write(s, x11_authnames[pr->disp->localauthproto],
- authstrlen);
- sk_write(s, zeroes, 3 & (-authstrlen));
- }
- if (realauthlen) {
- sk_write(s, realauthdata, realauthlen);
- sk_write(s, zeroes, 3 & (-realauthlen));
- }
- }
- pr->verified = 1;
- }
-
- /*
- * After initialisation, just copy data simply.
- */
-
- return sk_write(s, data, len);
-}
-
-void x11_send_eof(Socket s)
-{
- sk_write_eof(s);
-}
+/*
+ * Platform-independent bits of X11 forwarding.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <assert.h>
+#include <time.h>
+
+#include "putty.h"
+#include "ssh.h"
+#include "tree234.h"
+
+#define GET_16BIT(endian, cp) \
+ (endian=='B' ? GET_16BIT_MSB_FIRST(cp) : GET_16BIT_LSB_FIRST(cp))
+
+#define PUT_16BIT(endian, cp, val) \
+ (endian=='B' ? PUT_16BIT_MSB_FIRST(cp, val) : PUT_16BIT_LSB_FIRST(cp, val))
+
+const char *const x11_authnames[] = {
+ "", "MIT-MAGIC-COOKIE-1", "XDM-AUTHORIZATION-1"
+};
+
+struct XDMSeen {
+ unsigned int time;
+ unsigned char clientid[6];
+};
+
+struct X11Connection {
+ const struct plug_function_table *fn;
+ /* the above variable absolutely *must* be the first in this structure */
+ unsigned char firstpkt[12]; /* first X data packet */
+ tree234 *authtree;
+ struct X11Display *disp;
+ char *auth_protocol;
+ unsigned char *auth_data;
+ int data_read, auth_plen, auth_psize, auth_dlen, auth_dsize;
+ int verified;
+ int throttled, throttle_override;
+ int no_data_sent_to_x_client;
+ char *peer_addr;
+ int peer_port;
+ struct ssh_channel *c; /* channel structure held by ssh.c */
+ Socket s;
+};
+
+static int xdmseen_cmp(void *a, void *b)
+{
+ struct XDMSeen *sa = a, *sb = b;
+ return sa->time > sb->time ? 1 :
+ sa->time < sb->time ? -1 :
+ memcmp(sa->clientid, sb->clientid, sizeof(sa->clientid));
+}
+
+/* Do-nothing "plug" implementation, used by x11_setup_display() when it
+ * creates a trial connection (and then immediately closes it).
+ * XXX: bit out of place here, could in principle live in a platform-
+ * independent network.c or something */
+static void dummy_plug_log(Plug p, int type, SockAddr addr, int port,
+ const char *error_msg, int error_code) { }
+static int dummy_plug_closing
+ (Plug p, const char *error_msg, int error_code, int calling_back)
+{ return 1; }
+static int dummy_plug_receive(Plug p, int urgent, char *data, int len)
+{ return 1; }
+static void dummy_plug_sent(Plug p, int bufsize) { }
+static int dummy_plug_accepting(Plug p, accept_fn_t constructor, accept_ctx_t ctx) { return 1; }
+static const struct plug_function_table dummy_plug = {
+ dummy_plug_log, dummy_plug_closing, dummy_plug_receive,
+ dummy_plug_sent, dummy_plug_accepting
+};
+
+struct X11FakeAuth *x11_invent_fake_auth(tree234 *authtree, int authtype)
+{
+ struct X11FakeAuth *auth = snew(struct X11FakeAuth);
+ int i;
+
+ /*
+ * This function has the job of inventing a set of X11 fake auth
+ * data, and adding it to 'authtree'. We must preserve the
+ * property that for any given actual authorisation attempt, _at
+ * most one_ thing in the tree can possibly match it.
+ *
+ * For MIT-MAGIC-COOKIE-1, that's not too difficult: the match
+ * criterion is simply that the entire cookie is correct, so we
+ * just have to make sure we don't make up two cookies the same.
+ * (Vanishingly unlikely, but we check anyway to be sure, and go
+ * round again inventing a new cookie if add234 tells us the one
+ * we thought of is already in use.)
+ *
+ * For XDM-AUTHORIZATION-1, it's a little more fiddly. The setup
+ * with XA1 is that half the cookie is used as a DES key with
+ * which to CBC-encrypt an assortment of stuff. Happily, the stuff
+ * encrypted _begins_ with the other half of the cookie, and the
+ * IV is always zero, which means that any valid XA1 authorisation
+ * attempt for a given cookie must begin with the same cipher
+ * block, consisting of the DES ECB encryption of the first half
+ * of the cookie using the second half as a key. So we compute
+ * that cipher block here and now, and use it as the sorting key
+ * for distinguishing XA1 entries in the tree.
+ */
+
+ if (authtype == X11_MIT) {
+ auth->proto = X11_MIT;
+
+ /* MIT-MAGIC-COOKIE-1. Cookie size is 128 bits (16 bytes). */
+ auth->datalen = 16;
+ auth->data = snewn(auth->datalen, unsigned char);
+ auth->xa1_firstblock = NULL;
+
+ while (1) {
+ for (i = 0; i < auth->datalen; i++)
+ auth->data[i] = random_byte();
+ if (add234(authtree, auth) == auth)
+ break;
+ }
+
+ auth->xdmseen = NULL;
+ } else {
+ assert(authtype == X11_XDM);
+ auth->proto = X11_XDM;
+
+ /* XDM-AUTHORIZATION-1. Cookie size is 16 bytes; byte 8 is zero. */
+ auth->datalen = 16;
+ auth->data = snewn(auth->datalen, unsigned char);
+ auth->xa1_firstblock = snewn(8, unsigned char);
+ memset(auth->xa1_firstblock, 0, 8);
+
+ while (1) {
+ for (i = 0; i < auth->datalen; i++)
+ auth->data[i] = (i == 8 ? 0 : random_byte());
+ memcpy(auth->xa1_firstblock, auth->data, 8);
+ des_encrypt_xdmauth(auth->data + 9, auth->xa1_firstblock, 8);
+ if (add234(authtree, auth) == auth)
+ break;
+ }
+
+ auth->xdmseen = newtree234(xdmseen_cmp);
+ }
+ auth->protoname = dupstr(x11_authnames[auth->proto]);
+ auth->datastring = snewn(auth->datalen * 2 + 1, char);
+ for (i = 0; i < auth->datalen; i++)
+ sprintf(auth->datastring + i*2, "%02x",
+ auth->data[i]);
+
+ auth->disp = NULL;
+ auth->share_cs = auth->share_chan = NULL;
+
+ return auth;
+}
+
+void x11_free_fake_auth(struct X11FakeAuth *auth)
+{
+ if (auth->data)
+ smemclr(auth->data, auth->datalen);
+ sfree(auth->data);
+ sfree(auth->protoname);
+ sfree(auth->datastring);
+ sfree(auth->xa1_firstblock);
+ if (auth->xdmseen != NULL) {
+ struct XDMSeen *seen;
+ while ((seen = delpos234(auth->xdmseen, 0)) != NULL)
+ sfree(seen);
+ freetree234(auth->xdmseen);
+ }
+ sfree(auth);
+}
+
+int x11_authcmp(void *av, void *bv)
+{
+ struct X11FakeAuth *a = (struct X11FakeAuth *)av;
+ struct X11FakeAuth *b = (struct X11FakeAuth *)bv;
+
+ if (a->proto < b->proto)
+ return -1;
+ else if (a->proto > b->proto)
+ return +1;
+
+ if (a->proto == X11_MIT) {
+ if (a->datalen < b->datalen)
+ return -1;
+ else if (a->datalen > b->datalen)
+ return +1;
+
+ return memcmp(a->data, b->data, a->datalen);
+ } else {
+ assert(a->proto == X11_XDM);
+
+ return memcmp(a->xa1_firstblock, b->xa1_firstblock, 8);
+ }
+}
+
+struct X11Display *x11_setup_display(char *display, Conf *conf)
+{
+ struct X11Display *disp = snew(struct X11Display);
+ char *localcopy;
+
+ if (!display || !*display) {
+ localcopy = platform_get_x_display();
+ if (!localcopy || !*localcopy) {
+ sfree(localcopy);
+ localcopy = dupstr(":0"); /* plausible default for any platform */
+ }
+ } else
+ localcopy = dupstr(display);
+
+ /*
+ * Parse the display name.
+ *
+ * We expect this to have one of the following forms:
+ *
+ * - the standard X format which looks like
+ * [ [ protocol '/' ] host ] ':' displaynumber [ '.' screennumber ]
+ * (X11 also permits a double colon to indicate DECnet, but
+ * that's not our problem, thankfully!)
+ *
+ * - only seen in the wild on MacOS (so far): a pathname to a
+ * Unix-domain socket, which will typically and confusingly
+ * end in ":0", and which I'm currently distinguishing from
+ * the standard scheme by noting that it starts with '/'.
+ */
+ if (localcopy[0] == '/') {
+ disp->unixsocketpath = localcopy;
+ disp->unixdomain = TRUE;
+ disp->hostname = NULL;
+ disp->displaynum = -1;
+ disp->screennum = 0;
+ disp->addr = NULL;
+ } else {
+ char *colon, *dot, *slash;
+ char *protocol, *hostname;
+
+ colon = host_strrchr(localcopy, ':');
+ if (!colon) {
+ sfree(disp);
+ sfree(localcopy);
+ return NULL; /* FIXME: report a specific error? */
+ }
+
+ *colon++ = '\0';
+ dot = strchr(colon, '.');
+ if (dot)
+ *dot++ = '\0';
+
+ disp->displaynum = atoi(colon);
+ if (dot)
+ disp->screennum = atoi(dot);
+ else
+ disp->screennum = 0;
+
+ protocol = NULL;
+ hostname = localcopy;
+ if (colon > localcopy) {
+ slash = strchr(localcopy, '/');
+ if (slash) {
+ *slash++ = '\0';
+ protocol = localcopy;
+ hostname = slash;
+ }
+ }
+
+ disp->hostname = *hostname ? dupstr(hostname) : NULL;
+
+ if (protocol)
+ disp->unixdomain = (!strcmp(protocol, "local") ||
+ !strcmp(protocol, "unix"));
+ else if (!*hostname || !strcmp(hostname, "unix"))
+ disp->unixdomain = platform_uses_x11_unix_by_default;
+ else
+ disp->unixdomain = FALSE;
+
+ if (!disp->hostname && !disp->unixdomain)
+ disp->hostname = dupstr("localhost");
+
+ disp->unixsocketpath = NULL;
+ disp->addr = NULL;
+
+ sfree(localcopy);
+ }
+
+ /*
+ * Look up the display hostname, if we need to.
+ */
+ if (!disp->unixdomain) {
+ const char *err;
+
+ disp->port = 6000 + disp->displaynum;
+ disp->addr = name_lookup(disp->hostname, disp->port,
+ &disp->realhost, conf, ADDRTYPE_UNSPEC);
+
+ if ((err = sk_addr_error(disp->addr)) != NULL) {
+ sk_addr_free(disp->addr);
+ sfree(disp->hostname);
+ sfree(disp->unixsocketpath);
+ sfree(disp);
+ return NULL; /* FIXME: report an error */
+ }
+ }
+
+ /*
+ * Try upgrading an IP-style localhost display to a Unix-socket
+ * display (as the standard X connection libraries do).
+ */
+ if (!disp->unixdomain && sk_address_is_local(disp->addr)) {
+ SockAddr ux = platform_get_x11_unix_address(NULL, disp->displaynum);
+ const char *err = sk_addr_error(ux);
+ if (!err) {
+ /* Create trial connection to see if there is a useful Unix-domain
+ * socket */
+ const struct plug_function_table *dummy = &dummy_plug;
+ Socket s = sk_new(sk_addr_dup(ux), 0, 0, 0, 0, 0, (Plug)&dummy);
+ err = sk_socket_error(s);
+ sk_close(s);
+ }
+ if (err) {
+ sk_addr_free(ux);
+ } else {
+ sk_addr_free(disp->addr);
+ disp->unixdomain = TRUE;
+ disp->addr = ux;
+ /* Fill in the rest in a moment */
+ }
+ }
+
+ if (disp->unixdomain) {
+ if (!disp->addr)
+ disp->addr = platform_get_x11_unix_address(disp->unixsocketpath,
+ disp->displaynum);
+ if (disp->unixsocketpath)
+ disp->realhost = dupstr(disp->unixsocketpath);
+ else
+ disp->realhost = dupprintf("unix:%d", disp->displaynum);
+ disp->port = 0;
+ }
+
+ /*
+ * Fetch the local authorisation details.
+ */
+ disp->localauthproto = X11_NO_AUTH;
+ disp->localauthdata = NULL;
+ disp->localauthdatalen = 0;
+ platform_get_x11_auth(disp, conf);
+
+ return disp;
+}
+
+void x11_free_display(struct X11Display *disp)
+{
+ sfree(disp->hostname);
+ sfree(disp->unixsocketpath);
+ if (disp->localauthdata)
+ smemclr(disp->localauthdata, disp->localauthdatalen);
+ sfree(disp->localauthdata);
+ sk_addr_free(disp->addr);
+ sfree(disp);
+}
+
+#define XDM_MAXSKEW 20*60 /* 20 minute clock skew should be OK */
+
+static char *x11_verify(unsigned long peer_ip, int peer_port,
+ tree234 *authtree, char *proto,
+ unsigned char *data, int dlen,
+ struct X11FakeAuth **auth_ret)
+{
+ struct X11FakeAuth match_dummy; /* for passing to find234 */
+ struct X11FakeAuth *auth;
+
+ /*
+ * First, do a lookup in our tree to find the only authorisation
+ * record that _might_ match.
+ */
+ if (!strcmp(proto, x11_authnames[X11_MIT])) {
+ /*
+ * Just look up the whole cookie that was presented to us,
+ * which x11_authcmp will compare against the cookies we
+ * currently believe in.
+ */
+ match_dummy.proto = X11_MIT;
+ match_dummy.datalen = dlen;
+ match_dummy.data = data;
+ } else if (!strcmp(proto, x11_authnames[X11_XDM])) {
+ /*
+ * Look up the first cipher block, against the stored first
+ * cipher blocks for the XDM-AUTHORIZATION-1 cookies we
+ * currently know. (See comment in x11_invent_fake_auth.)
+ */
+ match_dummy.proto = X11_XDM;
+ match_dummy.xa1_firstblock = data;
+ } else {
+ return "Unsupported authorisation protocol";
+ }
+
+ if ((auth = find234(authtree, &match_dummy, 0)) == NULL)
+ return "Authorisation not recognised";
+
+ /*
+ * If we're using MIT-MAGIC-COOKIE-1, that was all we needed. If
+ * we're doing XDM-AUTHORIZATION-1, though, we have to check the
+ * rest of the auth data.
+ */
+ if (auth->proto == X11_XDM) {
+ unsigned long t;
+ time_t tim;
+ int i;
+ struct XDMSeen *seen, *ret;
+
+ if (dlen != 24)
+ return "XDM-AUTHORIZATION-1 data was wrong length";
+ if (peer_port == -1)
+ return "cannot do XDM-AUTHORIZATION-1 without remote address data";
+ des_decrypt_xdmauth(auth->data+9, data, 24);
+ if (memcmp(auth->data, data, 8) != 0)
+ return "XDM-AUTHORIZATION-1 data failed check"; /* cookie wrong */
+ if (GET_32BIT_MSB_FIRST(data+8) != peer_ip)
+ return "XDM-AUTHORIZATION-1 data failed check"; /* IP wrong */
+ if ((int)GET_16BIT_MSB_FIRST(data+12) != peer_port)
+ return "XDM-AUTHORIZATION-1 data failed check"; /* port wrong */
+ t = GET_32BIT_MSB_FIRST(data+14);
+ for (i = 18; i < 24; i++)
+ if (data[i] != 0) /* zero padding wrong */
+ return "XDM-AUTHORIZATION-1 data failed check";
+ tim = time(NULL);
+ if (abs(t - tim) > XDM_MAXSKEW)
+ return "XDM-AUTHORIZATION-1 time stamp was too far out";
+ seen = snew(struct XDMSeen);
+ seen->time = t;
+ memcpy(seen->clientid, data+8, 6);
+ assert(auth->xdmseen != NULL);
+ ret = add234(auth->xdmseen, seen);
+ if (ret != seen) {
+ sfree(seen);
+ return "XDM-AUTHORIZATION-1 data replayed";
+ }
+ /* While we're here, purge entries too old to be replayed. */
+ for (;;) {
+ seen = index234(auth->xdmseen, 0);
+ assert(seen != NULL);
+ if (t - seen->time <= XDM_MAXSKEW)
+ break;
+ sfree(delpos234(auth->xdmseen, 0));
+ }
+ }
+ /* implement other protocols here if ever required */
+
+ *auth_ret = auth;
+ return NULL;
+}
+
+void x11_get_auth_from_authfile(struct X11Display *disp,
+ const char *authfilename)
+{
+ FILE *authfp;
+ char *buf, *ptr, *str[4];
+ int len[4];
+ int family, protocol;
+ int ideal_match = FALSE;
+ char *ourhostname;
+
+ /*
+ * Normally we should look for precisely the details specified in
+ * `disp'. However, there's an oddity when the display is local:
+ * displays like "localhost:0" usually have their details stored
+ * in a Unix-domain-socket record (even if there isn't actually a
+ * real Unix-domain socket available, as with OpenSSH's proxy X11
+ * server).
+ *
+ * This is apparently a fudge to get round the meaninglessness of
+ * "localhost" in a shared-home-directory context -- xauth entries
+ * for Unix-domain sockets already disambiguate this by storing
+ * the *local* hostname in the conveniently-blank hostname field,
+ * but IP "localhost" records couldn't do this. So, typically, an
+ * IP "localhost" entry in the auth database isn't present and if
+ * it were it would be ignored.
+ *
+ * However, we don't entirely trust that (say) Windows X servers
+ * won't rely on a straight "localhost" entry, bad idea though
+ * that is; so if we can't find a Unix-domain-socket entry we'll
+ * fall back to an IP-based entry if we can find one.
+ */
+ int localhost = !disp->unixdomain && sk_address_is_local(disp->addr);
+
+ authfp = fopen(authfilename, "rb");
+ if (!authfp)
+ return;
+
+ ourhostname = get_hostname();
+
+ /* Records in .Xauthority contain four strings of up to 64K each */
+ buf = snewn(65537 * 4, char);
+
+ while (!ideal_match) {
+ int c, i, j, match = FALSE;
+
+#define GET do { c = fgetc(authfp); if (c == EOF) goto done; c = (unsigned char)c; } while (0)
+ /* Expect a big-endian 2-byte number giving address family */
+ GET; family = c;
+ GET; family = (family << 8) | c;
+ /* Then expect four strings, each composed of a big-endian 2-byte
+ * length field followed by that many bytes of data */
+ ptr = buf;
+ for (i = 0; i < 4; i++) {
+ GET; len[i] = c;
+ GET; len[i] = (len[i] << 8) | c;
+ str[i] = ptr;
+ for (j = 0; j < len[i]; j++) {
+ GET; *ptr++ = c;
+ }
+ *ptr++ = '\0';
+ }
+#undef GET
+
+ /*
+ * Now we have a full X authority record in memory. See
+ * whether it matches the display we're trying to
+ * authenticate to.
+ *
+ * The details we've just read should be interpreted as
+ * follows:
+ *
+ * - 'family' is the network address family used to
+ * connect to the display. 0 means IPv4; 6 means IPv6;
+ * 256 means Unix-domain sockets.
+ *
+ * - str[0] is the network address itself. For IPv4 and
+ * IPv6, this is a string of binary data of the
+ * appropriate length (respectively 4 and 16 bytes)
+ * representing the address in big-endian format, e.g.
+ * 7F 00 00 01 means IPv4 localhost. For Unix-domain
+ * sockets, this is the host name of the machine on
+ * which the Unix-domain display resides (so that an
+ * .Xauthority file on a shared file system can contain
+ * authority entries for Unix-domain displays on
+ * several machines without them clashing).
+ *
+ * - str[1] is the display number. I've no idea why
+ * .Xauthority stores this as a string when it has a
+ * perfectly good integer format, but there we go.
+ *
+ * - str[2] is the authorisation method, encoded as its
+ * canonical string name (i.e. "MIT-MAGIC-COOKIE-1",
+ * "XDM-AUTHORIZATION-1" or something we don't
+ * recognise).
+ *
+ * - str[3] is the actual authorisation data, stored in
+ * binary form.
+ */
+
+ if (disp->displaynum < 0 || disp->displaynum != atoi(str[1]))
+ continue; /* not the one */
+
+ for (protocol = 1; protocol < lenof(x11_authnames); protocol++)
+ if (!strcmp(str[2], x11_authnames[protocol]))
+ break;
+ if (protocol == lenof(x11_authnames))
+ continue; /* don't recognise this protocol, look for another */
+
+ switch (family) {
+ case 0: /* IPv4 */
+ if (!disp->unixdomain &&
+ sk_addrtype(disp->addr) == ADDRTYPE_IPV4) {
+ char buf[4];
+ sk_addrcopy(disp->addr, buf);
+ if (len[0] == 4 && !memcmp(str[0], buf, 4)) {
+ match = TRUE;
+ /* If this is a "localhost" entry, note it down
+ * but carry on looking for a Unix-domain entry. */
+ ideal_match = !localhost;
+ }
+ }
+ break;
+ case 6: /* IPv6 */
+ if (!disp->unixdomain &&
+ sk_addrtype(disp->addr) == ADDRTYPE_IPV6) {
+ char buf[16];
+ sk_addrcopy(disp->addr, buf);
+ if (len[0] == 16 && !memcmp(str[0], buf, 16)) {
+ match = TRUE;
+ ideal_match = !localhost;
+ }
+ }
+ break;
+ case 256: /* Unix-domain / localhost */
+ if ((disp->unixdomain || localhost)
+ && ourhostname && !strcmp(ourhostname, str[0]))
+ /* A matching Unix-domain socket is always the best
+ * match. */
+ match = ideal_match = TRUE;
+ break;
+ }
+
+ if (match) {
+ /* Current best guess -- may be overridden if !ideal_match */
+ disp->localauthproto = protocol;
+ sfree(disp->localauthdata); /* free previous guess, if any */
+ disp->localauthdata = snewn(len[3], unsigned char);
+ memcpy(disp->localauthdata, str[3], len[3]);
+ disp->localauthdatalen = len[3];
+ }
+ }
+
+ done:
+ fclose(authfp);
+ smemclr(buf, 65537 * 4);
+ sfree(buf);
+ sfree(ourhostname);
+}
+
+static void x11_log(Plug p, int type, SockAddr addr, int port,
+ const char *error_msg, int error_code)
+{
+ /* We have no interface to the logging module here, so we drop these. */
+}
+
+static void x11_send_init_error(struct X11Connection *conn,
+ const char *err_message);
+
+static int x11_closing(Plug plug, const char *error_msg, int error_code,
+ int calling_back)
+{
+ struct X11Connection *xconn = (struct X11Connection *) plug;
+
+ if (error_msg) {
+ /*
+ * Socket error. If we're still at the connection setup stage,
+ * construct an X11 error packet passing on the problem.
+ */
+ if (xconn->no_data_sent_to_x_client) {
+ char *err_message = dupprintf("unable to connect to forwarded "
+ "X server: %s", error_msg);
+ x11_send_init_error(xconn, err_message);
+ sfree(err_message);
+ }
+
+ /*
+ * Whether we did that or not, now we slam the connection
+ * shut.
+ */
+ sshfwd_unclean_close(xconn->c, error_msg);
+ } else {
+ /*
+ * Ordinary EOF received on socket. Send an EOF on the SSH
+ * channel.
+ */
+ if (xconn->c)
+ sshfwd_write_eof(xconn->c);
+ }
+
+ return 1;
+}
+
+static int x11_receive(Plug plug, int urgent, char *data, int len)
+{
+ struct X11Connection *xconn = (struct X11Connection *) plug;
+
+ if (sshfwd_write(xconn->c, data, len) > 0) {
+ xconn->throttled = 1;
+ xconn->no_data_sent_to_x_client = FALSE;
+ sk_set_frozen(xconn->s, 1);
+ }
+
+ return 1;
+}
+
+static void x11_sent(Plug plug, int bufsize)
+{
+ struct X11Connection *xconn = (struct X11Connection *) plug;
+
+ sshfwd_unthrottle(xconn->c, bufsize);
+}
+
+/*
+ * When setting up X forwarding, we should send the screen number
+ * from the specified local display. This function extracts it from
+ * the display string.
+ */
+int x11_get_screen_number(char *display)
+{
+ int n;
+
+ n = host_strcspn(display, ":");
+ if (!display[n])
+ return 0;
+ n = strcspn(display, ".");
+ if (!display[n])
+ return 0;
+ return atoi(display + n + 1);
+}
+
+/*
+ * Called to set up the X11Connection structure, though this does not
+ * yet connect to an actual server.
+ */
+struct X11Connection *x11_init(tree234 *authtree, void *c,
+ const char *peeraddr, int peerport)
+{
+ static const struct plug_function_table fn_table = {
+ x11_log,
+ x11_closing,
+ x11_receive,
+ x11_sent,
+ NULL
+ };
+
+ struct X11Connection *xconn;
+
+ /*
+ * Open socket.
+ */
+ xconn = snew(struct X11Connection);
+ xconn->fn = &fn_table;
+ xconn->auth_protocol = NULL;
+ xconn->authtree = authtree;
+ xconn->verified = 0;
+ xconn->data_read = 0;
+ xconn->throttled = xconn->throttle_override = 0;
+ xconn->no_data_sent_to_x_client = TRUE;
+ xconn->c = c;
+
+ /*
+ * We don't actually open a local socket to the X server just yet,
+ * because we don't know which one it is. Instead, we'll wait
+ * until we see the incoming authentication data, which may tell
+ * us what display to connect to, or whether we have to divert
+ * this X forwarding channel to a connection-sharing downstream
+ * rather than handling it ourself.
+ */
+ xconn->disp = NULL;
+ xconn->s = NULL;
+
+ /*
+ * Stash the peer address we were given in its original text form.
+ */
+ xconn->peer_addr = peeraddr ? dupstr(peeraddr) : NULL;
+ xconn->peer_port = peerport;
+
+ return xconn;
+}
+
+void x11_close(struct X11Connection *xconn)
+{
+ if (!xconn)
+ return;
+
+ if (xconn->auth_protocol) {
+ sfree(xconn->auth_protocol);
+ sfree(xconn->auth_data);
+ }
+
+ if (xconn->s)
+ sk_close(xconn->s);
+
+ sfree(xconn->peer_addr);
+ sfree(xconn);
+}
+
+void x11_unthrottle(struct X11Connection *xconn)
+{
+ if (!xconn)
+ return;
+
+ xconn->throttled = 0;
+ if (xconn->s)
+ sk_set_frozen(xconn->s, xconn->throttled || xconn->throttle_override);
+}
+
+void x11_override_throttle(struct X11Connection *xconn, int enable)
+{
+ if (!xconn)
+ return;
+
+ xconn->throttle_override = enable;
+ if (xconn->s)
+ sk_set_frozen(xconn->s, xconn->throttled || xconn->throttle_override);
+}
+
+static void x11_send_init_error(struct X11Connection *xconn,
+ const char *err_message)
+{
+ char *full_message;
+ int msglen, msgsize;
+ unsigned char *reply;
+
+ full_message = dupprintf("%s X11 proxy: %s\n", appname, err_message);
+
+ msglen = strlen(full_message);
+ reply = snewn(8 + msglen+1 + 4, unsigned char); /* include zero */
+ msgsize = (msglen + 3) & ~3;
+ reply[0] = 0; /* failure */
+ reply[1] = msglen; /* length of reason string */
+ memcpy(reply + 2, xconn->firstpkt + 2, 4); /* major/minor proto vsn */
+ PUT_16BIT(xconn->firstpkt[0], reply + 6, msgsize >> 2);/* data len */
+ memset(reply + 8, 0, msgsize);
+ memcpy(reply + 8, full_message, msglen);
+ sshfwd_write(xconn->c, (char *)reply, 8 + msgsize);
+ sshfwd_write_eof(xconn->c);
+ xconn->no_data_sent_to_x_client = FALSE;
+ sfree(reply);
+ sfree(full_message);
+}
+
+static int x11_parse_ip(const char *addr_string, unsigned long *ip)
+{
+
+ /*
+ * See if we can make sense of this string as an IPv4 address, for
+ * XDM-AUTHORIZATION-1 purposes.
+ */
+ int i[4];
+ if (addr_string &&
+ 4 == sscanf(addr_string, "%d.%d.%d.%d", i+0, i+1, i+2, i+3)) {
+ *ip = (i[0] << 24) | (i[1] << 16) | (i[2] << 8) | i[3];
+ return TRUE;
+ } else {
+ return FALSE;
+ }
+}
+
+/*
+ * Called to send data down the raw connection.
+ */
+int x11_send(struct X11Connection *xconn, char *data, int len)
+{
+ if (!xconn)
+ return 0;
+
+ /*
+ * Read the first packet.
+ */
+ while (len > 0 && xconn->data_read < 12)
+ xconn->firstpkt[xconn->data_read++] = (unsigned char) (len--, *data++);
+ if (xconn->data_read < 12)
+ return 0;
+
+ /*
+ * If we have not allocated the auth_protocol and auth_data
+ * strings, do so now.
+ */
+ if (!xconn->auth_protocol) {
+ xconn->auth_plen = GET_16BIT(xconn->firstpkt[0], xconn->firstpkt + 6);
+ xconn->auth_dlen = GET_16BIT(xconn->firstpkt[0], xconn->firstpkt + 8);
+ xconn->auth_psize = (xconn->auth_plen + 3) & ~3;
+ xconn->auth_dsize = (xconn->auth_dlen + 3) & ~3;
+ /* Leave room for a terminating zero, to make our lives easier. */
+ xconn->auth_protocol = snewn(xconn->auth_psize + 1, char);
+ xconn->auth_data = snewn(xconn->auth_dsize, unsigned char);
+ }
+
+ /*
+ * Read the auth_protocol and auth_data strings.
+ */
+ while (len > 0 &&
+ xconn->data_read < 12 + xconn->auth_psize)
+ xconn->auth_protocol[xconn->data_read++ - 12] = (len--, *data++);
+ while (len > 0 &&
+ xconn->data_read < 12 + xconn->auth_psize + xconn->auth_dsize)
+ xconn->auth_data[xconn->data_read++ - 12 -
+ xconn->auth_psize] = (unsigned char) (len--, *data++);
+ if (xconn->data_read < 12 + xconn->auth_psize + xconn->auth_dsize)
+ return 0;
+
+ /*
+ * If we haven't verified the authorisation, do so now.
+ */
+ if (!xconn->verified) {
+ const char *err;
+ struct X11FakeAuth *auth_matched = NULL;
+ unsigned long peer_ip;
+ int peer_port;
+ int protomajor, protominor;
+ void *greeting;
+ int greeting_len;
+ unsigned char *socketdata;
+ int socketdatalen;
+ char new_peer_addr[32];
+ int new_peer_port;
+
+ protomajor = GET_16BIT(xconn->firstpkt[0], xconn->firstpkt + 2);
+ protominor = GET_16BIT(xconn->firstpkt[0], xconn->firstpkt + 4);
+
+ assert(!xconn->s);
+
+ xconn->auth_protocol[xconn->auth_plen] = '\0'; /* ASCIZ */
+
+ peer_ip = 0; /* placate optimiser */
+ if (x11_parse_ip(xconn->peer_addr, &peer_ip))
+ peer_port = xconn->peer_port;
+ else
+ peer_port = -1; /* signal no peer address data available */
+
+ err = x11_verify(peer_ip, peer_port,
+ xconn->authtree, xconn->auth_protocol,
+ xconn->auth_data, xconn->auth_dlen, &auth_matched);
+ if (err) {
+ x11_send_init_error(xconn, err);
+ return 0;
+ }
+ assert(auth_matched);
+
+ /*
+ * If this auth points to a connection-sharing downstream
+ * rather than an X display we know how to connect to
+ * directly, pass it off to the sharing module now.
+ */
+ if (auth_matched->share_cs) {
+ sshfwd_x11_sharing_handover(xconn->c, auth_matched->share_cs,
+ auth_matched->share_chan,
+ xconn->peer_addr, xconn->peer_port,
+ xconn->firstpkt[0],
+ protomajor, protominor, data, len);
+ return 0;
+ }
+
+ /*
+ * Now we know we're going to accept the connection, and what
+ * X display to connect to. Actually connect to it.
+ */
+ sshfwd_x11_is_local(xconn->c);
+ xconn->disp = auth_matched->disp;
+ xconn->s = new_connection(sk_addr_dup(xconn->disp->addr),
+ xconn->disp->realhost, xconn->disp->port,
+ 0, 1, 0, 0, (Plug) xconn,
+ sshfwd_get_conf(xconn->c));
+ if ((err = sk_socket_error(xconn->s)) != NULL) {
+ char *err_message = dupprintf("unable to connect to"
+ " forwarded X server: %s", err);
+ x11_send_init_error(xconn, err_message);
+ sfree(err_message);
+ return 0;
+ }
+
+ /*
+ * Write a new connection header containing our replacement
+ * auth data.
+ */
+
+ socketdata = sk_getxdmdata(xconn->s, &socketdatalen);
+ if (socketdata && socketdatalen==6) {
+ sprintf(new_peer_addr, "%d.%d.%d.%d", socketdata[0],
+ socketdata[1], socketdata[2], socketdata[3]);
+ new_peer_port = GET_16BIT_MSB_FIRST(socketdata + 4);
+ } else {
+ strcpy(new_peer_addr, "0.0.0.0");
+ new_peer_port = 0;
+ }
+
+ greeting = x11_make_greeting(xconn->firstpkt[0],
+ protomajor, protominor,
+ xconn->disp->localauthproto,
+ xconn->disp->localauthdata,
+ xconn->disp->localauthdatalen,
+ new_peer_addr, new_peer_port,
+ &greeting_len);
+
+ sk_write(xconn->s, greeting, greeting_len);
+
+ smemclr(greeting, greeting_len);
+ sfree(greeting);
+
+ /*
+ * Now we're done.
+ */
+ xconn->verified = 1;
+ }
+
+ /*
+ * After initialisation, just copy data simply.
+ */
+
+ return sk_write(xconn->s, data, len);
+}
+
+void x11_send_eof(struct X11Connection *xconn)
+{
+ if (xconn->s) {
+ sk_write_eof(xconn->s);
+ } else {
+ /*
+ * If EOF is received from the X client before we've got to
+ * the point of actually connecting to an X server, then we
+ * should send an EOF back to the client so that the
+ * forwarded channel will be terminated.
+ */
+ if (xconn->c)
+ sshfwd_write_eof(xconn->c);
+ }
+}
+
+/*
+ * Utility functions used by connection sharing to convert textual
+ * representations of an X11 auth protocol name + hex cookie into our
+ * usual integer protocol id and binary auth data.
+ */
+int x11_identify_auth_proto(const char *protoname)
+{
+ int protocol;
+
+ for (protocol = 1; protocol < lenof(x11_authnames); protocol++)
+ if (!strcmp(protoname, x11_authnames[protocol]))
+ return protocol;
+ return -1;
+}
+
+void *x11_dehexify(const char *hex, int *outlen)
+{
+ int len, i;
+ unsigned char *ret;
+
+ len = strlen(hex) / 2;
+ ret = snewn(len, unsigned char);
+
+ for (i = 0; i < len; i++) {
+ char bytestr[3];
+ unsigned val = 0;
+ bytestr[0] = hex[2*i];
+ bytestr[1] = hex[2*i+1];
+ bytestr[2] = '\0';
+ sscanf(bytestr, "%x", &val);
+ ret[i] = val;
+ }
+
+ *outlen = len;
+ return ret;
+}
+
+/*
+ * Construct an X11 greeting packet, including making up the right
+ * authorisation data.
+ */
+void *x11_make_greeting(int endian, int protomajor, int protominor,
+ int auth_proto, const void *auth_data, int auth_len,
+ const char *peer_addr, int peer_port,
+ int *outlen)
+{
+ unsigned char *greeting;
+ unsigned char realauthdata[64];
+ const char *authname;
+ const unsigned char *authdata;
+ int authnamelen, authnamelen_pad;
+ int authdatalen, authdatalen_pad;
+ int greeting_len;
+
+ authname = x11_authnames[auth_proto];
+ authnamelen = strlen(authname);
+ authnamelen_pad = (authnamelen + 3) & ~3;
+
+ if (auth_proto == X11_MIT) {
+ authdata = auth_data;
+ authdatalen = auth_len;
+ } else if (auth_proto == X11_XDM && auth_len == 16) {
+ time_t t;
+ unsigned long peer_ip = 0;
+
+ x11_parse_ip(peer_addr, &peer_ip);
+
+ authdata = realauthdata;
+ authdatalen = 24;
+ memset(realauthdata, 0, authdatalen);
+ memcpy(realauthdata, auth_data, 8);
+ PUT_32BIT_MSB_FIRST(realauthdata+8, peer_ip);
+ PUT_16BIT_MSB_FIRST(realauthdata+12, peer_port);
+ t = time(NULL);
+ PUT_32BIT_MSB_FIRST(realauthdata+14, t);
+
+ des_encrypt_xdmauth((const unsigned char *)auth_data + 9,
+ realauthdata, authdatalen);
+ } else {
+ authdata = realauthdata;
+ authdatalen = 0;
+ }
+
+ authdatalen_pad = (authdatalen + 3) & ~3;
+ greeting_len = 12 + authnamelen_pad + authdatalen_pad;
+
+ greeting = snewn(greeting_len, unsigned char);
+ memset(greeting, 0, greeting_len);
+ greeting[0] = endian;
+ PUT_16BIT(endian, greeting+2, protomajor);
+ PUT_16BIT(endian, greeting+4, protominor);
+ PUT_16BIT(endian, greeting+6, authnamelen);
+ PUT_16BIT(endian, greeting+8, authdatalen);
+ memcpy(greeting+12, authname, authnamelen);
+ memcpy(greeting+12+authnamelen_pad, authdata, authdatalen);
+
+ smemclr(realauthdata, sizeof(realauthdata));
+
+ *outlen = greeting_len;
+ return greeting;
+}
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-22 19:31:27 +0000