X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=blobdiff_plain;f=x11fwd.c;h=584116aa69b29189ae93782da3ed0d5ffd15e2a8;hb=efdbe568e2d0ab58aa0330fda392c4c12f92dc1c;hp=80a0206c0ebf954ee6ec0535281e8b8c733c4fc5;hpb=01085358e43e662935598f588914867a731e963e;p=PuTTY.git diff --git a/x11fwd.c b/x11fwd.c index 80a0206c..584116aa 100644 --- a/x11fwd.c +++ b/x11fwd.c @@ -30,6 +30,7 @@ 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; @@ -37,7 +38,7 @@ struct X11Connection { int verified; int throttled, throttle_override; int no_data_sent_to_x_client; - unsigned long peer_ip; + char *peer_addr; int peer_port; struct ssh_channel *c; /* channel structure held by ssh.c */ Socket s; @@ -69,11 +70,130 @@ static const struct plug_function_table dummy_plug = { dummy_plug_sent, dummy_plug_accepting }; -struct X11Display *x11_setup_display(char *display, int authtype, Conf *conf) +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(const char *display, Conf *conf) { struct X11Display *disp = snew(struct X11Display); char *localcopy; - int i; if (!display || !*display) { localcopy = platform_get_x_display(); @@ -110,7 +230,7 @@ struct X11Display *x11_setup_display(char *display, int authtype, Conf *conf) char *colon, *dot, *slash; char *protocol, *hostname; - colon = strrchr(localcopy, ':'); + colon = host_strrchr(localcopy, ':'); if (!colon) { sfree(disp); sfree(localcopy); @@ -166,7 +286,8 @@ struct X11Display *x11_setup_display(char *display, int authtype, Conf *conf) disp->port = 6000 + disp->displaynum; disp->addr = name_lookup(disp->hostname, disp->port, - &disp->realhost, conf, ADDRTYPE_UNSPEC); + &disp->realhost, conf, ADDRTYPE_UNSPEC, + NULL, NULL); if ((err = sk_addr_error(disp->addr)) != NULL) { sk_addr_free(disp->addr); @@ -213,37 +334,6 @@ struct X11Display *x11_setup_display(char *display, int authtype, Conf *conf) 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. */ @@ -257,41 +347,59 @@ struct X11Display *x11_setup_display(char *display, int authtype, Conf *conf) 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) smemclr(disp->localauthdata, disp->localauthdatalen); sfree(disp->localauthdata); - if (disp->remoteauthdata) - smemclr(disp->remoteauthdata, 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) +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) { - 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"; + 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 (disp->remoteauthproto == 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; @@ -301,8 +409,8 @@ static char *x11_verify(unsigned long peer_ip, int peer_port, 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) + 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 */ @@ -313,27 +421,30 @@ 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) > XDM_MAXSKEW) + 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(disp->xdmseen != NULL); - ret = add234(disp->xdmseen, seen); + 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(disp->xdmseen, 0); + seen = index234(auth->xdmseen, 0); assert(seen != NULL); if (t - seen->time <= XDM_MAXSKEW) break; - sfree(delpos234(disp->xdmseen, 0)); + sfree(delpos234(auth->xdmseen, 0)); } } /* implement other protocols here if ever required */ + + *auth_ret = auth; return NULL; } @@ -568,7 +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, "."); @@ -578,14 +689,11 @@ int x11_get_screen_number(char *display) } /* - * Called to set up the raw connection. - * - * On success, returns NULL and fills in *xconnret. On error, returns - * a dynamically allocated error message string. + * Called to set up the X11Connection structure, though this does not + * yet connect to an actual server. */ -extern char *x11_init(struct X11Connection **xconnret, - struct X11Display *disp, void *c, - const char *peeraddr, int peerport) +struct X11Connection *x11_init(tree234 *authtree, void *c, + const char *peeraddr, int peerport) { static const struct plug_function_table fn_table = { x11_log, @@ -600,10 +708,10 @@ extern char *x11_init(struct X11Connection **xconnret, /* * Open socket. */ - xconn = *xconnret = snew(struct X11Connection); + xconn = snew(struct X11Connection); xconn->fn = &fn_table; xconn->auth_protocol = NULL; - xconn->disp = disp; + xconn->authtree = authtree; xconn->verified = 0; xconn->data_read = 0; xconn->throttled = xconn->throttle_override = 0; @@ -611,30 +719,23 @@ extern char *x11_init(struct X11Connection **xconnret, xconn->c = c; /* - * We don't actually open a local socket to the X server just yet. - * Instead, we'll wait until we see the incoming authentication - * data, which may tell us we have to divert this X forwarding - * channel to a connection-sharing downstream rather than handling - * it ourself. + * 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; /* - * 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)) { - xconn->peer_ip = (i[0] << 24) | (i[1] << 16) | (i[2] << 8) | i[3]; - xconn->peer_port = peerport; - } else { - xconn->peer_ip = 0; - xconn->peer_port = -1; - } - } + xconn->peer_addr = peeraddr ? dupstr(peeraddr) : NULL; + xconn->peer_port = peerport; - return NULL; + return xconn; } void x11_close(struct X11Connection *xconn) @@ -649,6 +750,8 @@ void x11_close(struct X11Connection *xconn) if (xconn->s) sk_close(xconn->s); + + sfree(xconn->peer_addr); sfree(xconn); } @@ -697,6 +800,23 @@ static void x11_send_init_error(struct X11Connection *xconn, 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. */ @@ -745,22 +865,59 @@ int x11_send(struct X11Connection *xconn, char *data, int len) */ 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 */ - err = x11_verify(xconn->peer_ip, xconn->peer_port, - xconn->disp, xconn->auth_protocol, - xconn->auth_data, xconn->auth_dlen); + + 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. Actually - * connect to the X server. + * 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, @@ -774,54 +931,36 @@ int x11_send(struct X11Connection *xconn, char *data, int len) } /* - * Strip the fake auth data, and optionally put real auth data - * in instead. + * Write a new connection header containing our replacement + * auth data. */ - { - char realauthdata[64]; - int realauthlen = 0; - int authstrlen = strlen(x11_authnames[xconn->disp->localauthproto]); - int buflen = 0; /* initialise to placate optimiser */ - static const char zeroes[4] = { 0,0,0,0 }; - void *buf; - - if (xconn->disp->localauthproto == X11_MIT) { - assert(xconn->disp->localauthdatalen <= lenof(realauthdata)); - realauthlen = xconn->disp->localauthdatalen; - memcpy(realauthdata, xconn->disp->localauthdata, realauthlen); - } else if (xconn->disp->localauthproto == X11_XDM && - xconn->disp->localauthdatalen == 16 && - ((buf = sk_getxdmdata(xconn->s, &buflen))!=0)) { - time_t t; - realauthlen = (buflen+12+7) & ~7; - assert(realauthlen <= lenof(realauthdata)); - memset(realauthdata, 0, realauthlen); - memcpy(realauthdata, xconn->disp->localauthdata, 8); - memcpy(realauthdata+8, buf, buflen); - t = time(NULL); - PUT_32BIT_MSB_FIRST(realauthdata+8+buflen, t); - des_encrypt_xdmauth(xconn->disp->localauthdata+9, - (unsigned char *)realauthdata, - realauthlen); - sfree(buf); - } - /* 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(xconn->firstpkt[0], xconn->firstpkt + 6, authstrlen); - PUT_16BIT(xconn->firstpkt[0], xconn->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(xconn->s, (char *)xconn->firstpkt, 12); - - if (authstrlen) { - sk_write(xconn->s, x11_authnames[xconn->disp->localauthproto], - authstrlen); - sk_write(xconn->s, zeroes, 3 & (-authstrlen)); - } - if (realauthlen) { - sk_write(xconn->s, realauthdata, realauthlen); - sk_write(xconn->s, zeroes, 3 & (-realauthlen)); - } - } + sk_write(xconn->s, greeting, greeting_len); + + smemclr(greeting, greeting_len); + sfree(greeting); + + /* + * Now we're done. + */ xconn->verified = 1; } @@ -847,3 +986,105 @@ void x11_send_eof(struct X11Connection *xconn) 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; +}