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add length checks and comments to proxy LCP parsing
[l2tpns.git] / ppp.c
diff --git a/ppp.c b/ppp.c
index cd51e37..c3d00b1 100644 (file)
--- a/ppp.c
+++ b/ppp.c
@@ -1,6 +1,6 @@
 // L2TPNS PPP Stuff
 
 // L2TPNS PPP Stuff
 
-char const *cvs_id_ppp = "$Id: ppp.c,v 1.12 2004/08/13 00:02:50 fred_nerk Exp $";
+char const *cvs_id_ppp = "$Id: ppp.c,v 1.20 2004/11/05 02:21:55 bodea Exp $";
 
 #include <stdio.h>
 #include <string.h>
 
 #include <stdio.h>
 #include <string.h>
@@ -26,11 +26,11 @@ extern struct configt *config;
 void sendccp(tunnelidt t, sessionidt s);
 
 // Process PAP messages
 void sendccp(tunnelidt t, sessionidt s);
 
 // Process PAP messages
-void processpap(tunnelidt t, sessionidt s, u8 * p, u16 l)
+void processpap(tunnelidt t, sessionidt s, u8 *p, u16 l)
 {
        char user[129];
        char pass[129];
 {
        char user[129];
        char pass[129];
-
+       u16 hl;
 
        CSTAT(call_processpap);
 
 
        CSTAT(call_processpap);
 
@@ -41,18 +41,22 @@ void processpap(tunnelidt t, sessionidt s, u8 * p, u16 l)
                STAT(tunnel_rx_errors);
                return ;
        }
                STAT(tunnel_rx_errors);
                return ;
        }
-       if (*p != 1)
+
+       if ((hl = ntohs(*(u16 *) (p + 2))) > l)
        {
        {
-               log(1, 0, s, t, "Unexpected PAP code %d\n", *p);
+               log(1, 0, s, t, "Length mismatch PAP %u/%u\n", hl, l);
                STAT(tunnel_rx_errors);
                return ;
        }
                STAT(tunnel_rx_errors);
                return ;
        }
-       if (ntohs(*(u16 *) (p + 2)) > l)
+       l = hl;
+
+       if (*p != 1)
        {
        {
-               log(1, 0, s, t, "Length mismatch PAP %d/%d\n", ntohs(*(u16 *) (p + 2)), l);
+               log(1, 0, s, t, "Unexpected PAP code %d\n", *p);
                STAT(tunnel_rx_errors);
                return ;
        }
                STAT(tunnel_rx_errors);
                return ;
        }
+
        {
                u8 *b = p;
                b += 4;
        {
                u8 *b = p;
                b += 4;
@@ -123,11 +127,10 @@ void processpap(tunnelidt t, sessionidt s, u8 * p, u16 l)
 }
 
 // Process CHAP messages
 }
 
 // Process CHAP messages
-void processchap(tunnelidt t, sessionidt s, u8 * p, u16 l)
+void processchap(tunnelidt t, sessionidt s, u8 *p, u16 l)
 {
        u16 r;
 {
        u16 r;
-       u16 len;
-
+       u16 hl;
 
        CSTAT(call_processchap);
 
 
        CSTAT(call_processchap);
 
@@ -142,6 +145,22 @@ void processchap(tunnelidt t, sessionidt s, u8 * p, u16 l)
                STAT(tunnel_rx_errors);
                return;
        }
                STAT(tunnel_rx_errors);
                return;
        }
+
+       if (l < 4)
+       {
+               log(1, 0, s, t, "Short CHAP %u bytes\n", l);
+               STAT(tunnel_rx_errors);
+               return ;
+       }
+
+       if ((hl = ntohs(*(u16 *) (p + 2))) > l)
+       {
+               log(1, 0, s, t, "Length mismatch CHAP %u/%u\n", hl, l);
+               STAT(tunnel_rx_errors);
+               return ;
+       }
+       l = hl;
+
        if (*p != 2)
        {
                log(1, 0, s, t, "Unexpected CHAP response code %d\n", *p);
        if (*p != 2)
        {
                log(1, 0, s, t, "Unexpected CHAP response code %d\n", *p);
@@ -154,22 +173,19 @@ void processchap(tunnelidt t, sessionidt s, u8 * p, u16 l)
                STAT(tunnel_rx_errors);
                return ;
        }
                STAT(tunnel_rx_errors);
                return ;
        }
-       len = ntohs(*(u16 *) (p + 2));
-       if (len > l)
-       {
-               log(1, 0, s, t, "Bad CHAP length %d\n", len);
-               STAT(tunnel_rx_errors);
-               return ;
-       }
-       if (p[4] != 16)
+
+       if (l < 5 || p[4] != 16)
        {
        {
-               log(1, 0, s, t, "Bad CHAP response length %d\n", p[4]);
+               log(1, 0, s, t, "Bad CHAP response length %d\n", l < 5 ? -1 : p[4]);
                STAT(tunnel_rx_errors);
                return ;
        }
                STAT(tunnel_rx_errors);
                return ;
        }
-       if (len - 21 >= sizeof(session[s].user))
+
+       l -= 5;
+       p += 5;
+       if (l < 16 || l - 16 >= sizeof(session[s].user))
        {
        {
-               log(1, 0, s, t, "CHAP user too long %d\n", len - 21);
+               log(1, 0, s, t, "CHAP user too long %d\n", l - 16);
                STAT(tunnel_rx_errors);
                return ;
        }
                STAT(tunnel_rx_errors);
                return ;
        }
@@ -178,10 +194,14 @@ void processchap(tunnelidt t, sessionidt s, u8 * p, u16 l)
        {
                struct param_pre_auth packet = { &tunnel[t], &session[s], NULL, NULL, PPPCHAP, 1 };
 
        {
                struct param_pre_auth packet = { &tunnel[t], &session[s], NULL, NULL, PPPCHAP, 1 };
 
-               packet.username = calloc(len-20, 1);
-               packet.password = calloc(16, 1);
-               memcpy(packet.username, p + 21, len - 21);
-               memcpy(packet.password, p + 5, 16);
+               packet.password = calloc(17, 1);
+               memcpy(packet.password, p, 16);
+
+               p += 16;
+               l -= 16;
+
+               packet.username = calloc(l + 1, 1);
+               memcpy(packet.username, p, l);
 
                run_plugins(PLUGIN_PRE_AUTH, &packet);
                if (!packet.continue_auth)
 
                run_plugins(PLUGIN_PRE_AUTH, &packet);
                if (!packet.continue_auth)
@@ -222,7 +242,7 @@ char *ppp_lcp_types[] = {
 
 void dumplcp(u8 *p, int l)
 {
 
 void dumplcp(u8 *p, int l)
 {
-       signed int x = l - 4;
+       int x = l - 4;
        u8 *o = (p + 4);
 
        log_hex(5, "PPP LCP Packet", p, l);
        u8 *o = (p + 4);
 
        log_hex(5, "PPP LCP Packet", p, l);
@@ -251,7 +271,7 @@ void dumplcp(u8 *p, int l)
                {
                        case 1: // Maximum-Receive-Unit
                                if (length == 4)
                {
                        case 1: // Maximum-Receive-Unit
                                if (length == 4)
-                               log(4, 0, 0, 0, "    %s %d\n", lcp_types[type], ntohs(*(u16 *)(o + 2)));
+                                       log(4, 0, 0, 0, "    %s %d\n", lcp_types[type], ntohs(*(u16 *)(o + 2)));
                                else
                                        log(4, 0, 0, 0, "    %s odd length %d\n", lcp_types[type], length);
                                break;
                                else
                                        log(4, 0, 0, 0, "    %s odd length %d\n", lcp_types[type], length);
                                break;
@@ -259,10 +279,10 @@ void dumplcp(u8 *p, int l)
                                {
                                        if (length == 4)
                                        {
                                {
                                        if (length == 4)
                                        {
-                                       int proto = ntohs(*(u16 *)(o + 2));
+                                               int proto = ntohs(*(u16 *)(o + 2));
                                                log(4, 0, 0, 0, "   %s 0x%x (%s)\n", lcp_types[type], proto,
                                                log(4, 0, 0, 0, "   %s 0x%x (%s)\n", lcp_types[type], proto,
-                                                       proto == 0xC223 ? "CHAP" :
-                                                       proto == 0xC023 ? "PAP"  : "UNKNOWN");
+                                                       proto == PPPCHAP ? "CHAP" :
+                                                       proto == PPPPAP  ? "PAP"  : "UNKNOWN");
                                        }
                                        else
                                                log(4, 0, 0, 0, "   %s odd length %d\n", lcp_types[type], length);
                                        }
                                        else
                                                log(4, 0, 0, 0, "   %s odd length %d\n", lcp_types[type], length);
@@ -278,8 +298,8 @@ void dumplcp(u8 *p, int l)
                                {
                                        if (length == 6)
                                        {
                                {
                                        if (length == 6)
                                        {
-                                       u32 magicno = ntohl(*(u32 *)(o + 2));
-                                       log(4, 0, 0, 0, "    %s %x\n", lcp_types[type], magicno);
+                                               u32 magicno = ntohl(*(u32 *)(o + 2));
+                                               log(4, 0, 0, 0, "    %s %x\n", lcp_types[type], magicno);
                                        }
                                        else
                                                log(4, 0, 0, 0, "   %s odd length %d\n", lcp_types[type], length);
                                        }
                                        else
                                                log(4, 0, 0, 0, "   %s odd length %d\n", lcp_types[type], length);
@@ -305,12 +325,12 @@ void dumplcp(u8 *p, int l)
 }
 
 // Process LCP messages
 }
 
 // Process LCP messages
-void processlcp(tunnelidt t, sessionidt s, u8 * p, u16 l)
+void processlcp(tunnelidt t, sessionidt s, u8 *p, u16 l)
 {
        u8 b[MAXCONTROL];
        u8 *q = NULL;
 {
        u8 b[MAXCONTROL];
        u8 *q = NULL;
-       u32  magicno = 0;
-
+       u32 magicno = 0;
+       u16 hl;
 
        CSTAT(call_processlcp);
 
 
        CSTAT(call_processlcp);
 
@@ -321,6 +341,15 @@ void processlcp(tunnelidt t, sessionidt s, u8 * p, u16 l)
                STAT(tunnel_rx_errors);
                return ;
        }
                STAT(tunnel_rx_errors);
                return ;
        }
+
+       if ((hl = ntohs(*(u16 *) (p + 2))) > l)
+       {
+               log(1, 0, s, t, "Length mismatch LCP %u/%u\n", hl, l);
+               STAT(tunnel_rx_errors);
+               return ;
+       }
+       l = hl;
+
        if (*p == ConfigAck)
        {
                log(3, session[s].ip, s, t, "LCP: Discarding ConfigAck\n");
        if (*p == ConfigAck)
        {
                log(3, session[s].ip, s, t, "LCP: Discarding ConfigAck\n");
@@ -328,11 +357,11 @@ void processlcp(tunnelidt t, sessionidt s, u8 * p, u16 l)
        }
        else if (*p == ConfigReq)
        {
        }
        else if (*p == ConfigReq)
        {
-               signed int x = l - 4;
+               int x = l - 4;
                u8 *o = (p + 4);
 
                log(3, session[s].ip, s, t, "LCP: ConfigReq (%d bytes)...\n", l);
                u8 *o = (p + 4);
 
                log(3, session[s].ip, s, t, "LCP: ConfigReq (%d bytes)...\n", l);
-               dumplcp(p, l);
+               if (config->debug > 3) dumplcp(p, l);
 
                while (x > 2)
                {
 
                while (x > 2)
                {
@@ -351,7 +380,7 @@ void processlcp(tunnelidt t, sessionidt s, u8 * p, u16 l)
                                case 3: // Authentication-Protocol
                                        {
                                                int proto = ntohs(*(u16 *)(o + 2));
                                case 3: // Authentication-Protocol
                                        {
                                                int proto = ntohs(*(u16 *)(o + 2));
-                                               if (proto == 0xC223)
+                                               if (proto == PPPCHAP)
                                                {
                                                        log(2, session[s].ip, s, t, "    Remote end is trying to do CHAP. Rejecting it.\n");
 
                                                {
                                                        log(2, session[s].ip, s, t, "    Remote end is trying to do CHAP. Rejecting it.\n");
 
@@ -365,7 +394,7 @@ void processlcp(tunnelidt t, sessionidt s, u8 * p, u16 l)
                                                                *q++ = ConfigNak;
                                                        }
                                                        memcpy(q, o, length);
                                                                *q++ = ConfigNak;
                                                        }
                                                        memcpy(q, o, length);
-                                                       *(u16 *)(q += 2) = htons(0xC023); // NAK -> Use PAP instead
+                                                       *(u16 *)(q += 2) = htons(PPPPAP); // NAK -> Use PAP instead
                                                        q += length;
                                                }
                                                break;
                                                        q += length;
                                                }
                                                break;
@@ -411,8 +440,8 @@ void processlcp(tunnelidt t, sessionidt s, u8 * p, u16 l)
                {
                        // Send back a ConfigAck
                        log(3, session[s].ip, s, t, "ConfigReq accepted, sending as Ack\n");
                {
                        // Send back a ConfigAck
                        log(3, session[s].ip, s, t, "ConfigReq accepted, sending as Ack\n");
-                       // for  win2k L2TP clientis  and LCP renegotiation of alive session 
-                       if (magicno || l == 4) initlcp(t, s);
+                       // for win2k L2TP clients and LCP renegotiation of alive session
+                       if (magicno || l == 4 || (session[s].mru && l == 8)) initlcp(t, s);
                        q = makeppp(b, sizeof(b), p, l, t, s, PPPLCP);
                        if (!q)
                        {
                        q = makeppp(b, sizeof(b), p, l, t, s, PPPLCP);
                        if (!q)
                        {
@@ -435,7 +464,7 @@ void processlcp(tunnelidt t, sessionidt s, u8 * p, u16 l)
        else if (*p == ConfigNak)
        {
                log(1, session[s].ip, s, t, "Remote end sent a ConfigNak. Ignoring\n");
        else if (*p == ConfigNak)
        {
                log(1, session[s].ip, s, t, "Remote end sent a ConfigNak. Ignoring\n");
-               dumplcp(p, l);
+               if (config->debug > 3) dumplcp(p, l);
                return ;
        }
        else if (*p == TerminateReq)
                return ;
        }
        else if (*p == TerminateReq)
@@ -496,8 +525,9 @@ void processlcp(tunnelidt t, sessionidt s, u8 * p, u16 l)
 }
 
 // Process IPCP messages
 }
 
 // Process IPCP messages
-void processipcp(tunnelidt t, sessionidt s, u8 * p, u16 l)
+void processipcp(tunnelidt t, sessionidt s, u8 *p, u16 l)
 {
 {
+       u16 hl;
 
        CSTAT(call_processipcp);
 
 
        CSTAT(call_processipcp);
 
@@ -508,11 +538,21 @@ void processipcp(tunnelidt t, sessionidt s, u8 * p, u16 l)
                STAT(tunnel_rx_errors);
                return ;
        }
                STAT(tunnel_rx_errors);
                return ;
        }
+
+       if ((hl = ntohs(*(u16 *) (p + 2))) > l)
+       {
+               log(1, 0, s, t, "Length mismatch IPCP %u/%u\n", hl, l);
+               STAT(tunnel_rx_errors);
+               return ;
+       }
+       l = hl;
+
        if (*p == ConfigAck)
        {
                // happy with our IPCP
                u16 r = session[s].radius;
        if (*p == ConfigAck)
        {
                // happy with our IPCP
                u16 r = session[s].radius;
-               if ((!r || radius[r].state == RADIUSIPCP) && !session[s].walled_garden) {
+               if ((!r || radius[r].state == RADIUSIPCP) && !session[s].walled_garden)
+               {
                        if (!r)
                                r = radiusnew(s);
                        if (r)
                        if (!r)
                                r = radiusnew(s);
                        if (r)
@@ -530,12 +570,7 @@ void processipcp(tunnelidt t, sessionidt s, u8 * p, u16 l)
                return ;
        }
        log(4, session[s].ip, s, t, "IPCP ConfigReq received\n");
                return ;
        }
        log(4, session[s].ip, s, t, "IPCP ConfigReq received\n");
-       if (ntohs(*(u16 *) (p + 2)) > l)
-       {
-               log(1, 0, s, t, "Length mismatch IPCP %d/%d\n", ntohs(*(u16 *) (p + 2)), l);
-               STAT(tunnel_rx_errors);
-               return ;
-       }
+
        if (!session[s].ip)
        {
                log(3, 0, s, t, "Waiting on radius reply\n");
        if (!session[s].ip)
        {
                log(3, 0, s, t, "Waiting on radius reply\n");
@@ -547,7 +582,6 @@ void processipcp(tunnelidt t, sessionidt s, u8 * p, u16 l)
                u8 *i,
                *q;
 
                u8 *i,
                *q;
 
-               l = ntohs(*(u16 *) (p + 2)); // We must use length from IPCP len field
                q = p + 4;
                i = p + l;
                while (q < i && q[1])
                q = p + 4;
                i = p + l;
                while (q < i && q[1])
@@ -632,11 +666,10 @@ void processipcp(tunnelidt t, sessionidt s, u8 * p, u16 l)
 //
 // This MUST be called with at least 4 byte behind 'p'.
 // (i.e. this routine writes to p[-4]).
 //
 // This MUST be called with at least 4 byte behind 'p'.
 // (i.e. this routine writes to p[-4]).
-void processipin(tunnelidt t, sessionidt s, u8 * p, u16 l)
+void processipin(tunnelidt t, sessionidt s, u8 *p, u16 l)
 {
        ipt ip;
 
 {
        ipt ip;
 
-
        CSTAT(call_processipin);
 
        log_hex(5, "IP", p, l);
        CSTAT(call_processipin);
 
        log_hex(5, "IP", p, l);
@@ -657,6 +690,12 @@ void processipin(tunnelidt t, sessionidt s, u8 * p, u16 l)
                return;
        }
 
                return;
        }
 
+       if (session[s].snoop_ip && session[s].snoop_port)
+       {
+               // Snooping this session
+               snoop_send_packet(p, l, session[s].snoop_ip, session[s].snoop_port);
+       }
+
        // Add on the tun header
        p -= 4;
        *(u32 *)p = htonl(0x00000800);
        // Add on the tun header
        p -= 4;
        *(u32 *)p = htonl(0x00000800);
@@ -674,11 +713,6 @@ void processipin(tunnelidt t, sessionidt s, u8 * p, u16 l)
        session[s].pin++;
        eth_tx += l - 4;
 
        session[s].pin++;
        eth_tx += l - 4;
 
-       if (session[s].snoop_ip && session[s].snoop_port)
-       {
-               // Snooping this session, send it to ASIO
-               snoop_send_packet(p, l, session[s].snoop_ip, session[s].snoop_port);
-       }
        STAT(tun_tx_packets);
        INC_STAT(tun_tx_bytes, l);
 
        STAT(tun_tx_packets);
        INC_STAT(tun_tx_bytes, l);
 
@@ -722,7 +756,7 @@ void send_ipin(sessionidt s, u8 *buf, int len)
 
 
 // Process LCP messages
 
 
 // Process LCP messages
-void processccp(tunnelidt t, sessionidt s, u8 * p, u16 l)
+void processccp(tunnelidt t, sessionidt s, u8 *p, u16 l)
 {
 
        CSTAT(call_processccp);
 {
 
        CSTAT(call_processccp);
@@ -730,7 +764,7 @@ void processccp(tunnelidt t, sessionidt s, u8 * p, u16 l)
        log_hex(5, "CCP", p, l);
        if (l < 2 || (*p != ConfigReq && *p != TerminateReq))
        {
        log_hex(5, "CCP", p, l);
        if (l < 2 || (*p != ConfigReq && *p != TerminateReq))
        {
-               log(1, 0, s, t, "Unexpecetd CCP request code %d\n", *p);
+               log(1, 0, s, t, "Unexpected CCP request code %d\n", *p);
                STAT(tunnel_rx_errors);
                return ;
        }
                STAT(tunnel_rx_errors);
                return ;
        }
@@ -812,9 +846,8 @@ void sendchap(tunnelidt t, sessionidt s)
 // fill in a L2TP message with a PPP frame,
 // copies existing PPP message and changes magic number if seen
 // returns start of PPP frame
 // fill in a L2TP message with a PPP frame,
 // copies existing PPP message and changes magic number if seen
 // returns start of PPP frame
-u8 *makeppp(u8 * b, int size, u8 * p, int l, tunnelidt t, sessionidt s, u16 mtype)
+u8 *makeppp(u8 *b, int size, u8 *p, int l, tunnelidt t, sessionidt s, u16 mtype)
 {
 {
-
        if (size < 12)
                return NULL;    // Need more space than this!!
 
        if (size < 12)
                return NULL;    // Need more space than this!!
 
@@ -822,7 +855,7 @@ u8 *makeppp(u8 * b, int size, u8 * p, int l, tunnelidt t, sessionidt s, u16 mtyp
        *(u16 *) (b + 2) = htons(tunnel[t].far); // tunnel
        *(u16 *) (b + 4) = htons(session[s].far); // session
        b += 6;
        *(u16 *) (b + 2) = htons(tunnel[t].far); // tunnel
        *(u16 *) (b + 4) = htons(session[s].far); // session
        b += 6;
-       if (mtype && !(session[s].l2tp_flags & SESSIONACFC))
+       if (mtype == PPPLCP || !(session[s].l2tp_flags & SESSIONACFC))
        {
                *(u16 *) b = htons(0xFF03); // HDLC header
                b += 2;
        {
                *(u16 *) b = htons(0xFF03); // HDLC header
                b += 2;
@@ -845,7 +878,7 @@ u8 *makeppp(u8 * b, int size, u8 * p, int l, tunnelidt t, sessionidt s, u16 mtyp
 }
 
 // find a PPP option, returns point to option, or 0 if not found
 }
 
 // find a PPP option, returns point to option, or 0 if not found
-u8 *findppp(u8 * b, u8 mtype)
+u8 *findppp(u8 *b, u8 mtype)
 {
        u16 l = ntohs(*(u16 *) (b + 2));
        if (l < 4)
 {
        u16 l = ntohs(*(u16 *) (b + 2));
        if (l < 4)
@@ -883,7 +916,7 @@ void initlcp(tunnelidt t, sessionidt s)
        *(u32 *)(q + 6) = htonl(session[s].magic);
        *(u8 *)(q + 10) = 3;
        *(u8 *)(q + 11) = 4;
        *(u32 *)(q + 6) = htonl(session[s].magic);
        *(u8 *)(q + 10) = 3;
        *(u8 *)(q + 11) = 4;
-       *(u16 *)(q + 12) = htons(0xC023); // PAP
+       *(u16 *)(q + 12) = htons(PPPPAP); // PAP
        tunnelsend(b, 12 + 14, t);
 }
 
        tunnelsend(b, 12 + 14, t);
 }
 
for cloning use: "git clone git://git.sameswireless.fr/l2tpns.git" ; For add to your sources.list: "deb http://package.sameswifi.fr/ jessie main"