X-Git-Url: http://pileus.org/git/?a=blobdiff_plain;f=ntlmsubr.c;h=057c1b9147c5a338468ac1dd56356b9bcf52fa3c;hb=e4dd196b137223195739b9e0f50ec2a8a02b3534;hp=ab685ff04a23a850429db89cae63430457e43a3c;hpb=269cba9b00fa7ecb0d707ef5b6f10d34e049327c;p=~andy%2Ffetchmail

diff --git a/ntlmsubr.c b/ntlmsubr.c
index ab685ff0..057c1b91 100644
--- a/ntlmsubr.c
+++ b/ntlmsubr.c
@@ -2,6 +2,7 @@
 
 #ifdef NTLM_ENABLE
 #include "fetchmail.h"
+#include "i18n.h"
 #include "ntlm.h"
 #include "socket.h"
 
@@ -29,8 +30,13 @@ int ntlm_helper(int sock, struct query *ctl, const char *proto)
     if ((result = gen_recv(sock, msgbuf, sizeof msgbuf)))
 	return result;
 
-    if (0 != strcmp(msgbuf, "+ "))
-	return PS_AUTHFAIL;
+    if (msgbuf[0] != '+' && strspn(msgbuf+1, " \t") < strlen(msgbuf+1)) {
+	if (outlevel >= O_VERBOSE) {
+	    report(stdout, GT_("Warning: received malformed challenge to \"AUTH(ENTICATE) NTLM\"!\n"));
+	}
+	result = PS_AUTHFAIL;
+	goto cancelfail;
+    }
 
     buildSmbNtlmAuthRequest(&request,ctl->remotename,NULL);
 
@@ -46,10 +52,39 @@ int ntlm_helper(int sock, struct query *ctl, const char *proto)
     strcat(msgbuf,"\r\n");
     SockWrite (sock, msgbuf, strlen (msgbuf));
 
-    if ((gen_recv(sock, msgbuf, sizeof msgbuf)))
-	return result;
-
-    (void)from64tobits (&challenge, msgbuf, sizeof(challenge));
+    if ((result = gen_recv(sock, msgbuf, sizeof msgbuf)))
+	goto cancelfail;
+
+    /*
+     * < 0: decoding error
+     * >= 0 < 32: too short to be plausible
+     */
+    if ((result = from64tobits (&challenge, msgbuf, sizeof(challenge))) < 0
+	    || result < 32)
+    {
+	report (stderr, GT_("could not decode BASE64 challenge\n"));
+	/* We do not goto cancelfail; the server has already sent the
+	 * tagged reply, so the protocol exchange has ended, no need
+	 * for us to send the asterisk. */
+	return PS_AUTHFAIL;
+    }
+
+    /* validate challenge:
+     * - ident
+     * - message type
+     * - that offset points into buffer
+     * - that offset + length does not wrap
+     * - that offset + length is not bigger than buffer */
+    if (0 != memcmp("NTLMSSP", challenge.ident, 8)
+	    || challenge.msgType != 2
+	    || challenge.uDomain.offset > (unsigned)result
+	    || (challenge.uDomain.offset + challenge.uDomain.len) < challenge.uDomain.offset
+	    || (challenge.uDomain.offset + challenge.uDomain.len) > (unsigned)result)
+    {
+	report (stderr, GT_("NTLM challenge contains invalid data.\n"));
+	result = PS_AUTHFAIL;
+	goto cancelfail;
+    }
 
     if (outlevel >= O_DEBUG)
 	dumpSmbNtlmAuthChallenge(stdout, &challenge);
@@ -69,6 +104,14 @@ int ntlm_helper(int sock, struct query *ctl, const char *proto)
     SockWrite (sock, msgbuf, strlen (msgbuf));
 
     return PS_SUCCESS;
+
+cancelfail: /* cancel authentication and return failure */
+    {
+	if (outlevel >= O_MONITOR)
+	    report(stdout, "%s> *\n", proto);
+	SockWrite(sock, "*\r\n", 3);
+	return result;
+    }
 }
 
 #endif /* NTLM_ENABLE */