X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=blobdiff_plain;f=x11fwd.c;h=584116aa69b29189ae93782da3ed0d5ffd15e2a8;hb=510f49e405e71ba5c97875e7a019364e1ef5fac9;hp=d748da1377584026c4bd1b1b9b420812dc953d92;hpb=2a41bc0808e3eff6848e3bb7dc3942ef9a6c6cde;p=PuTTY.git diff --git a/x11fwd.c b/x11fwd.c index d748da13..584116aa 100644 --- a/x11fwd.c +++ b/x11fwd.c @@ -9,46 +9,7 @@ #include "putty.h" #include "ssh.h" - -#define GET_32BIT_LSB_FIRST(cp) \ - (((unsigned long)(unsigned char)(cp)[0]) | \ - ((unsigned long)(unsigned char)(cp)[1] << 8) | \ - ((unsigned long)(unsigned char)(cp)[2] << 16) | \ - ((unsigned long)(unsigned char)(cp)[3] << 24)) - -#define PUT_32BIT_LSB_FIRST(cp, value) ( \ - (cp)[0] = (char)(value), \ - (cp)[1] = (char)((value) >> 8), \ - (cp)[2] = (char)((value) >> 16), \ - (cp)[3] = (char)((value) >> 24) ) - -#define GET_16BIT_LSB_FIRST(cp) \ - (((unsigned long)(unsigned char)(cp)[0]) | \ - ((unsigned long)(unsigned char)(cp)[1] << 8)) - -#define PUT_16BIT_LSB_FIRST(cp, value) ( \ - (cp)[0] = (char)(value), \ - (cp)[1] = (char)((value) >> 8) ) - -#define GET_32BIT_MSB_FIRST(cp) \ - (((unsigned long)(unsigned char)(cp)[0] << 24) | \ - ((unsigned long)(unsigned char)(cp)[1] << 16) | \ - ((unsigned long)(unsigned char)(cp)[2] << 8) | \ - ((unsigned long)(unsigned char)(cp)[3])) - -#define PUT_32BIT_MSB_FIRST(cp, value) ( \ - (cp)[0] = (char)((value) >> 24), \ - (cp)[1] = (char)((value) >> 16), \ - (cp)[2] = (char)((value) >> 8), \ - (cp)[3] = (char)(value) ) - -#define GET_16BIT_MSB_FIRST(cp) \ - (((unsigned long)(unsigned char)(cp)[0] << 8) | \ - ((unsigned long)(unsigned char)(cp)[1])) - -#define PUT_16BIT_MSB_FIRST(cp, value) ( \ - (cp)[0] = (char)((value) >> 8), \ - (cp)[1] = (char)(value) ) +#include "tree234.h" #define GET_16BIT(endian, cp) \ (endian=='B' ? GET_16BIT_MSB_FIRST(cp) : GET_16BIT_LSB_FIRST(cp)) @@ -60,107 +21,396 @@ const char *const x11_authnames[] = { "", "MIT-MAGIC-COOKIE-1", "XDM-AUTHORIZATION-1" }; -struct X11Auth { - unsigned char fakedata[64], realdata[64]; - int fakeproto, realproto; - int fakelen, reallen; +struct XDMSeen { + unsigned int time; + unsigned char clientid[6]; }; -struct X11Private { +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 */ - struct X11Auth *auth; + 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; - unsigned long peer_ip; + int no_data_sent_to_x_client; + char *peer_addr; int peer_port; - void *c; /* data used by ssh.c */ + struct ssh_channel *c; /* channel structure held by ssh.c */ Socket s; }; -void *x11_invent_auth(char *proto, int protomaxlen, - char *data, int datamaxlen, int proto_id) +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 X11Auth *auth = snew(struct X11Auth); - char ourdata[64]; + struct X11FakeAuth *auth = snew(struct X11FakeAuth); int i; - if (proto_id == X11_MIT) { - auth->fakeproto = X11_MIT; + /* + * 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->fakelen = 16; - for (i = 0; i < 16; i++) - auth->fakedata[i] = random_byte(); + 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(proto_id == X11_XDM); - auth->fakeproto = X11_XDM; + assert(authtype == X11_XDM); + auth->proto = X11_XDM; /* XDM-AUTHORIZATION-1. Cookie size is 16 bytes; byte 8 is zero. */ - auth->fakelen = 16; - for (i = 0; i < 16; i++) - auth->fakedata[i] = (i == 8 ? 0 : random_byte()); + 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]); - /* Now format for the recipient. */ - strncpy(proto, x11_authnames[auth->fakeproto], protomaxlen); - ourdata[0] = '\0'; - for (i = 0; i < auth->fakelen; i++) - sprintf(ourdata + strlen(ourdata), "%02x", auth->fakedata[i]); - strncpy(data, ourdata, datamaxlen); + auth->disp = NULL; + auth->share_cs = auth->share_chan = NULL; return auth; } -void x11_free_auth(void *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); } -/* - * Fetch the real auth data for a given display string, and store - * it in an X11Auth structure. Returns NULL on success, or an error - * string. - */ -void x11_get_real_auth(void *authv, char *display) +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(const char *display, Conf *conf) { - struct X11Auth *auth = (struct X11Auth *)authv; + 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, + NULL, NULL); + + 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 */ + } + } - auth->realproto = X11_NO_AUTH; /* in case next call does nothing */ + 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; + } - auth->reallen = sizeof(auth->realdata); - platform_get_x11_auth(display, &auth->realproto, - auth->realdata, &auth->reallen); + /* + * Fetch the local authorisation details. + */ + disp->localauthproto = X11_NO_AUTH; + disp->localauthdata = NULL; + disp->localauthdatalen = 0; + platform_get_x11_auth(disp, conf); + + return disp; } -static char *x11_verify(unsigned long peer_ip, int peer_port, - struct X11Auth *auth, char *proto, - unsigned char *data, int dlen) +void x11_free_display(struct X11Display *disp) { - if (strcmp(proto, x11_authnames[auth->fakeproto]) != 0) - return "wrong authentication protocol attempted"; - if (auth->fakeproto == X11_MIT) { - if (dlen != auth->fakelen) - return "MIT-MAGIC-COOKIE-1 data was wrong length"; - if (memcmp(auth->fakedata, data, dlen) != 0) - return "MIT-MAGIC-COOKIE-1 data did not match"; + 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 const 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->fakeproto == X11_XDM) { + + 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->fakedata+9, data, 24); - if (memcmp(auth->fakedata, data, 8) != 0) + 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 */ @@ -171,35 +421,243 @@ static char *x11_verify(unsigned long peer_ip, int peer_port, if (data[i] != 0) /* zero padding wrong */ return "XDM-AUTHORIZATION-1 data failed check"; tim = time(NULL); - if (abs(t - tim) > 20*60) /* 20 minute clock skew should be OK */ + if (((unsigned long)t - (unsigned long)tim + + XDM_MAXSKEW) > 2*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; } -static int x11_closing(Plug plug, const char *error_msg, int error_code, - int calling_back) +void x11_get_auth_from_authfile(struct X11Display *disp, + const char *authfilename) { - struct X11Private *pr = (struct X11Private *) plug; + FILE *authfp; + char *buf, *ptr, *str[4]; + int len[4]; + int family, protocol; + int ideal_match = FALSE; + char *ourhostname; /* - * 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. + * 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. */ - sshfwd_close(pr->c); - x11_close(pr->s); + 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 X11Private *pr = (struct X11Private *) plug; + struct X11Connection *xconn = (struct X11Connection *) plug; - if (sshfwd_write(pr->c, data, len) > 0) { - pr->throttled = 1; - sk_set_frozen(pr->s, 1); + 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; @@ -207,9 +665,9 @@ static int x11_receive(Plug plug, int urgent, char *data, int len) static void x11_sent(Plug plug, int bufsize) { - struct X11Private *pr = (struct X11Private *) plug; + struct X11Connection *xconn = (struct X11Connection *) plug; - sshfwd_unthrottle(pr->c, bufsize); + sshfwd_unthrottle(xconn->c, bufsize); } /* @@ -221,7 +679,7 @@ int x11_get_screen_number(char *display) { int n; - n = strcspn(display, ":"); + n = host_strcspn(display, ":"); if (!display[n]) return 0; n = strcspn(display, "."); @@ -230,294 +688,403 @@ int x11_get_screen_number(char *display) return atoi(display + n + 1); } -/* Find the right display, returns an allocated string */ -char *x11_display(const char *display) { - char *ret; - if(!display || !*display) { - /* try to find platform-specific local display */ - if(!(ret = platform_get_x_display())) - /* plausible default for all platforms */ - ret = dupstr(":0"); - } else - ret = dupstr(display); - if(ret[0] == ':') { - /* no transport specified, use whatever we think is best */ - char *s = dupcat(platform_x11_best_transport, ret, (char *)0); - sfree(ret); - return s; - } else - return ret; -} - /* - * Called to set up the raw connection. - * - * Returns an error message, or NULL on success. - * also, fills the SocketsStructure + * Called to set up the X11Connection structure, though this does not + * yet connect to an actual server. */ -const char *x11_init(Socket * s, char *display, void *c, void *auth, - const char *peeraddr, int peerport, const Config *cfg) +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 }; - SockAddr addr; - int port; - const char *err; - char *dummy_realhost; - char host[128]; - int n, displaynum; - struct X11Private *pr; + struct X11Connection *xconn; - /* default display */ - display = x11_display(display); /* - * Split up display name into host and display-number parts. + * Open socket. */ - n = strcspn(display, ":"); - assert(n != 0); /* x11_display() promises this */ - if (display[n]) - displaynum = atoi(display + n + 1); - else - displaynum = 0; /* sensible default */ - if (n > sizeof(host) - 1) - n = sizeof(host) - 1; - strncpy(host, display, n); - host[n] = '\0'; - sfree(display); - - if(!strcmp(host, "unix")) { - /* use AF_UNIX sockets (doesn't make sense on all platforms) */ - addr = platform_get_x11_unix_address(displaynum, - &dummy_realhost); - port = 0; /* to show we are not confused */ - } else { - port = 6000 + displaynum; - - /* - * Try to find host. - */ - addr = name_lookup(host, port, &dummy_realhost, cfg); - if ((err = sk_addr_error(addr)) != NULL) { - sk_addr_free(addr); - return err; - } - } + 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; /* - * Open socket. + * 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. */ - pr = snew(struct X11Private); - pr->fn = &fn_table; - pr->auth_protocol = NULL; - pr->auth = (struct X11Auth *)auth; - pr->verified = 0; - pr->data_read = 0; - pr->throttled = pr->throttle_override = 0; - pr->c = c; - - pr->s = *s = new_connection(addr, dummy_realhost, port, - 0, 1, 0, 0, (Plug) pr, cfg); - if ((err = sk_socket_error(*s)) != NULL) { - sfree(pr); - return err; - } + xconn->disp = NULL; + xconn->s = NULL; /* - * See if we can make sense of the peer address we were given. + * Stash the peer address we were given in its original text form. */ - { - 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; - } - } + xconn->peer_addr = peeraddr ? dupstr(peeraddr) : NULL; + xconn->peer_port = peerport; - sk_set_private_ptr(*s, pr); - return NULL; + return xconn; } -void x11_close(Socket s) +void x11_close(struct X11Connection *xconn) { - struct X11Private *pr; - if (!s) + if (!xconn) return; - pr = (struct X11Private *) sk_get_private_ptr(s); - if (pr->auth_protocol) { - sfree(pr->auth_protocol); - sfree(pr->auth_data); + + if (xconn->auth_protocol) { + sfree(xconn->auth_protocol); + sfree(xconn->auth_data); } - sfree(pr); + if (xconn->s) + sk_close(xconn->s); - sk_close(s); + sfree(xconn->peer_addr); + sfree(xconn); } -void x11_unthrottle(Socket s) +void x11_unthrottle(struct X11Connection *xconn) { - struct X11Private *pr; - if (!s) + if (!xconn) return; - pr = (struct X11Private *) sk_get_private_ptr(s); - pr->throttled = 0; - sk_set_frozen(s, pr->throttled || pr->throttle_override); + xconn->throttled = 0; + if (xconn->s) + sk_set_frozen(xconn->s, xconn->throttled || xconn->throttle_override); } -void x11_override_throttle(Socket s, int enable) +void x11_override_throttle(struct X11Connection *xconn, int enable) { - struct X11Private *pr; - if (!s) + if (!xconn) return; - pr = (struct X11Private *) sk_get_private_ptr(s); - pr->throttle_override = enable; - sk_set_frozen(s, pr->throttled || pr->throttle_override); + 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(Socket s, char *data, int len) +int x11_send(struct X11Connection *xconn, char *data, int len) { - struct X11Private *pr; - if (!s) + if (!xconn) 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) + 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 (!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; + 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. */ - pr->auth_protocol = snewn(pr->auth_psize + 1, char); - pr->auth_data = snewn(pr->auth_dsize, unsigned char); + 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 && 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) + 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 authentication, do so now. + * 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->auth, pr->auth_protocol, - pr->auth_data, pr->auth_dlen); - - /* - * If authentication failed, construct and send an error - * packet, then terminate the connection. - */ + 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) { - char *message; - int msglen, msgsize; - unsigned char *reply; - - message = dupprintf("PuTTY X11 proxy: %s", 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_close(pr->c); - x11_close(s); - sfree(reply); - sfree(message); - return 0; - } + 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. Strip - * the fake auth data, and optionally put real auth data in - * instead. + /* + * 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. */ - { - char realauthdata[64]; - int realauthlen = 0; - int authstrlen = strlen(x11_authnames[pr->auth->realproto]); - unsigned long ip; - int port; - static const char zeroes[4] = { 0,0,0,0 }; - - if (pr->auth->realproto == X11_MIT) { - assert(pr->auth->reallen <= lenof(realauthdata)); - realauthlen = pr->auth->reallen; - memcpy(realauthdata, pr->auth->realdata, realauthlen); - } else if (pr->auth->realproto == X11_XDM && - pr->auth->reallen == 16 && - sk_getxdmdata(s, &ip, &port)) { - time_t t; - realauthlen = 24; - memset(realauthdata, 0, 24); - memcpy(realauthdata, pr->auth->realdata, 8); - PUT_32BIT_MSB_FIRST(realauthdata+8, ip); - PUT_16BIT_MSB_FIRST(realauthdata+12, port); - t = time(NULL); - PUT_32BIT_MSB_FIRST(realauthdata+14, t); - des_encrypt_xdmauth(pr->auth->realdata+9, - (unsigned char *)realauthdata, 24); - } - /* implement other auth methods here if required */ + socketdatalen = 0; /* placate compiler warning */ + 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; + } - PUT_16BIT(pr->firstpkt[0], pr->firstpkt + 6, authstrlen); - PUT_16BIT(pr->firstpkt[0], pr->firstpkt + 8, realauthlen); + 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(s, (char *)pr->firstpkt, 12); - - if (authstrlen) { - sk_write(s, x11_authnames[pr->auth->realproto], authstrlen); - sk_write(s, zeroes, 3 & (-authstrlen)); - } - if (realauthlen) { - sk_write(s, realauthdata, realauthlen); - sk_write(s, zeroes, 3 & (-realauthlen)); - } - } - pr->verified = 1; + 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(s, data, len); + 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; }