+/*
+ * Platform-independent bits of X11 forwarding.
+ */
+
#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#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] = (value), \
- (cp)[1] = (value) >> 8, \
- (cp)[2] = (value) >> 16, \
- (cp)[3] = (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] = (value), \
- (cp)[1] = (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] = (value) >> 24, \
- (cp)[1] = (value) >> 16, \
- (cp)[2] = (value) >> 8, \
- (cp)[3] = (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] = (value) >> 8, \
- (cp)[1] = (value) )
+#include "tree234.h"
#define GET_16BIT(endian, cp) \
(endian=='B' ? GET_16BIT_MSB_FIRST(cp) : GET_16BIT_LSB_FIRST(cp))
"", "MIT-MAGIC-COOKIE-1", "XDM-AUTHORIZATION-1"
};
+struct XDMSeen {
+ unsigned int time;
+ unsigned char clientid[6];
+};
+
struct X11Auth {
unsigned char fakedata[64], realdata[64];
int fakeproto, realproto;
int fakelen, reallen;
+ tree234 *xdmseen;
};
struct X11Private {
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));
+}
+
void *x11_invent_auth(char *proto, int protomaxlen,
- char *data, int datamaxlen)
+ char *data, int datamaxlen, int proto_id)
{
- struct X11Auth *auth = smalloc(sizeof(struct X11Auth));
+ struct X11Auth *auth = snew(struct X11Auth);
char ourdata[64];
int i;
- auth->fakeproto = X11_MIT;
+ if (proto_id == X11_MIT) {
+ auth->fakeproto = 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();
+ /* 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->xdmseen = NULL;
+ } else {
+ assert(proto_id == X11_XDM);
+ auth->fakeproto = 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->xdmseen = newtree234(xdmseen_cmp);
+ }
/* Now format for the recipient. */
strncpy(proto, x11_authnames[auth->fakeproto], protomaxlen);
return auth;
}
+void x11_free_auth(void *authv)
+{
+ struct X11Auth *auth = (struct X11Auth *)authv;
+ struct XDMSeen *seen;
+
+ if (auth->xdmseen != NULL) {
+ 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
auth->realdata, &auth->reallen);
}
-static int x11_verify(struct X11Auth *auth,
- char *proto, unsigned char *data, int dlen)
+#define XDM_MAXSKEW 20*60 /* 20 minute clock skew should be OK */
+
+static char *x11_verify(unsigned long peer_ip, int peer_port,
+ struct X11Auth *auth, char *proto,
+ unsigned char *data, int dlen)
{
if (strcmp(proto, x11_authnames[auth->fakeproto]) != 0)
- return 0; /* wrong protocol attempted */
+ return "wrong authentication protocol attempted";
if (auth->fakeproto == X11_MIT) {
if (dlen != auth->fakelen)
- return 0; /* cookie was wrong length */
+ return "MIT-MAGIC-COOKIE-1 data was wrong length";
if (memcmp(auth->fakedata, data, dlen) != 0)
- return 0; /* cookie was wrong cookie! */
+ return "MIT-MAGIC-COOKIE-1 data did not match";
+ }
+ if (auth->fakeproto == 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)
+ 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 */
- return 1;
+ return NULL;
+}
+
+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, char *error_msg, int error_code,
+static int x11_closing(Plug plug, const char *error_msg, int error_code,
int calling_back)
{
struct X11Private *pr = (struct X11Private *) plug;
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())==0 || !*ret)
+ /* 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
*/
-char *x11_init(Socket * s, char *display, void *c, void *auth)
+const char *x11_init(Socket * s, char *display, void *c, void *auth,
+ const char *peeraddr, int peerport, const Config *cfg)
{
static const struct plug_function_table fn_table = {
+ x11_log,
x11_closing,
x11_receive,
x11_sent,
SockAddr addr;
int port;
- char *err, *dummy_realhost;
+ const char *err;
+ char *dummy_realhost;
char host[128];
int n, displaynum;
struct X11Private *pr;
+ /* default display */
+ display = x11_display(display);
/*
* Split up display name into host and display-number parts.
*/
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;
- if (n > 0) {
- strncpy(host, display, n);
- host[n] = '\0';
+ 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;
+
/*
- * Local display numbers, particularly on Unix, often omit
- * the display part completely.
+ * Try to find host.
*/
- strcpy(host, "localhost");
+ addr = name_lookup(host, port, &dummy_realhost, cfg, ADDRTYPE_UNSPEC);
+ if ((err = sk_addr_error(addr)) != NULL) {
+ sk_addr_free(addr);
+ return err;
+ }
}
- port = 6000 + displaynum;
-
- /*
- * Try to find host.
- */
- addr = name_lookup(host, port, &dummy_realhost);
- if ((err = sk_addr_error(addr)) != NULL)
- return err;
-
/*
* Open socket.
*/
- pr = (struct X11Private *) smalloc(sizeof(struct X11Private));
+ pr = snew(struct X11Private);
pr->fn = &fn_table;
pr->auth_protocol = NULL;
pr->auth = (struct X11Auth *)auth;
pr->throttled = pr->throttle_override = 0;
pr->c = c;
- pr->s = *s = new_connection(addr, dummy_realhost, port, 0, 1, 0, (Plug) pr);
+ 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;
}
+ /*
+ * 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);
- sk_addr_free(addr);
return NULL;
}
*/
int x11_send(Socket s, char *data, int len)
{
- struct X11Private *pr = (struct X11Private *) sk_get_private_ptr(s);
-
- if (s == NULL)
+ struct X11Private *pr;
+ if (!s)
return 0;
+ pr = (struct X11Private *) sk_get_private_ptr(s);
/*
* Read the first packet.
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 = (char *) smalloc(pr->auth_psize + 1);
- pr->auth_data = (unsigned char *) smalloc(pr->auth_dsize);
+ pr->auth_protocol = snewn(pr->auth_psize + 1, char);
+ pr->auth_data = snewn(pr->auth_dsize, unsigned char);
}
/*
* If we haven't verified the authentication, do so now.
*/
if (!pr->verified) {
- int ret;
+ char *err;
pr->auth_protocol[pr->auth_plen] = '\0'; /* ASCIZ */
- ret = x11_verify(pr->auth, pr->auth_protocol,
+ 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 (!ret) {
- char message[] = "Authentication failed at PuTTY X11 proxy";
- unsigned char reply[8 + sizeof(message) + 4];
- int msglen = sizeof(message) - 1; /* skip zero byte */
- int msgsize = (msglen + 3) & ~3;
+ 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 */
sshfwd_write(pr->c, (char *)reply, 8 + msgsize);
sshfwd_close(pr->c);
x11_close(s);
+ sfree(reply);
+ sfree(message);
return 0;
}
char realauthdata[64];
int realauthlen = 0;
int authstrlen = strlen(x11_authnames[pr->auth->realproto]);
- unsigned long ip;
- int port;
+ int buflen;
static const char zeroes[4] = { 0,0,0,0 };
+ void *buf;
if (pr->auth->realproto == X11_MIT) {
assert(pr->auth->reallen <= lenof(realauthdata));
memcpy(realauthdata, pr->auth->realdata, realauthlen);
} else if (pr->auth->realproto == X11_XDM &&
pr->auth->reallen == 16 &&
- sk_getxdmdata(s, &ip, &port)) {
+ ((buf = sk_getxdmdata(s, &buflen))!=0)) {
time_t t;
- realauthlen = 24;
- memset(realauthdata, 0, 24);
+ realauthlen = (buflen+12+7) & ~7;
+ assert(realauthlen <= lenof(realauthdata));
+ memset(realauthdata, 0, realauthlen);
memcpy(realauthdata, pr->auth->realdata, 8);
- PUT_32BIT_MSB_FIRST(realauthdata+8, ip);
- PUT_16BIT_MSB_FIRST(realauthdata+12, port);
+ memcpy(realauthdata+8, buf, buflen);
t = time(NULL);
- PUT_32BIT_MSB_FIRST(realauthdata+14, t);
+ PUT_32BIT_MSB_FIRST(realauthdata+8+buflen, t);
des_encrypt_xdmauth(pr->auth->realdata+9,
- (unsigned char *)realauthdata, 24);
+ (unsigned char *)realauthdata,
+ realauthlen);
+ sfree(buf);
}
/* implement other auth methods here if required */