#include "putty.h"
#include "ssh.h"
+#include "tree234.h"
#define GET_32BIT_LSB_FIRST(cp) \
(((unsigned long)(unsigned char)(cp)[0]) | \
"", "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 {
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, int proto_id)
{
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. */
return auth;
}
-void x11_free_auth(void *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);
}
auth->realdata, &auth->reallen);
}
+#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)
unsigned long t;
time_t tim;
int i;
+ struct XDMSeen *seen, *ret;
if (dlen != 24)
return "XDM-AUTHORIZATION-1 data was wrong length";
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 (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 NULL;