Port forwarding now works in SSH 2 as well as SSH 1.
[u/mdw/putty] / ssh.c
diff --git a/ssh.c b/ssh.c
index cbcf439..f6828dd 100644 (file)
--- a/ssh.c
+++ b/ssh.c
@@ -95,6 +95,8 @@
 #define SSH2_MSG_USERAUTH_BANNER                  53   /* 0x35 */
 #define SSH2_MSG_USERAUTH_PK_OK                   60   /* 0x3c */
 #define SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ        60   /* 0x3c */
+#define SSH2_MSG_USERAUTH_INFO_REQUEST            60   /* 0x3c */
+#define SSH2_MSG_USERAUTH_INFO_RESPONSE           61   /* 0x3d */
 #define SSH2_MSG_GLOBAL_REQUEST                   80   /* 0x50 */
 #define SSH2_MSG_REQUEST_SUCCESS                  81   /* 0x51 */
 #define SSH2_MSG_REQUEST_FAILURE                  82   /* 0x52 */
@@ -269,7 +271,8 @@ enum {                                     /* channel types */
     CHAN_MAINSESSION,
     CHAN_X11,
     CHAN_AGENT,
-    CHAN_SOCKDATA
+    CHAN_SOCKDATA,
+    CHAN_SOCKDATA_DORMANT             /* one the remote hasn't confirmed */
 };
 
 /*
@@ -300,13 +303,37 @@ struct ssh_channel {
 };
 
 /*
- * 2-3-4 tree storing remote->local port forwardings (so we can
- * reject any attempt to open a port we didn't explicitly ask to
- * have forwarded).
+ * 2-3-4 tree storing remote->local port forwardings. SSH 1 and SSH
+ * 2 use this structure in different ways, reflecting SSH 2's
+ * altogether saner approach to port forwarding.
+ * 
+ * In SSH 1, you arrange a remote forwarding by sending the server
+ * the remote port number, and the local destination host:port.
+ * When a connection comes in, the server sends you back that
+ * host:port pair, and you connect to it. This is a ready-made
+ * security hole if you're not on the ball: a malicious server
+ * could send you back _any_ host:port pair, so if you trustingly
+ * connect to the address it gives you then you've just opened the
+ * entire inside of your corporate network just by connecting
+ * through it to a dodgy SSH server. Hence, we must store a list of
+ * host:port pairs we _are_ trying to forward to, and reject a
+ * connection request from the server if it's not in the list.
+ * 
+ * In SSH 2, each side of the connection minds its own business and
+ * doesn't send unnecessary information to the other. You arrange a
+ * remote forwarding by sending the server just the remote port
+ * number. When a connection comes in, the server tells you which
+ * of its ports was connected to; and _you_ have to remember what
+ * local host:port pair went with that port number.
+ * 
+ * Hence: in SSH 1 this structure stores host:port pairs we intend
+ * to allow connections to, and is indexed by those host:port
+ * pairs. In SSH 2 it stores a mapping from source port to
+ * destination host:port pair, and is indexed by source port.
  */
 struct ssh_rportfwd {
-    unsigned port;
-    char host[256];
+    unsigned sport, dport;
+    char dhost[256];
 };
 
 struct Packet {
@@ -415,15 +442,29 @@ static int ssh_channelfind(void *av, void *bv)
     return 0;
 }
 
-static int ssh_rportcmp(void *av, void *bv)
+static int ssh_rportcmp_ssh1(void *av, void *bv)
 {
     struct ssh_rportfwd *a = (struct ssh_rportfwd *) av;
     struct ssh_rportfwd *b = (struct ssh_rportfwd *) bv;
     int i;
-    if ( (i = strcmp(a->host, b->host)) != 0)
+    if ( (i = strcmp(a->dhost, b->dhost)) != 0)
        return i < 0 ? -1 : +1;
-    if (a->port > b->port)
+    if (a->dport > b->dport)
+       return +1;
+    if (a->dport < b->dport)
+       return -1;
+    return 0;
+}
+
+static int ssh_rportcmp_ssh2(void *av, void *bv)
+{
+    struct ssh_rportfwd *a = (struct ssh_rportfwd *) av;
+    struct ssh_rportfwd *b = (struct ssh_rportfwd *) bv;
+    int i;
+    if (a->sport > b->sport)
        return +1;
+    if (a->sport < b->sport)
+       return -1;
     return 0;
 }
 
@@ -2381,7 +2422,7 @@ static void ssh1_protocol(unsigned char *in, int inlen, int ispkt)
        char sports[256], dports[256], host[256];
        char buf[1024];
 
-       ssh_rportfwds = newtree234(ssh_rportcmp);
+       ssh_rportfwds = newtree234(ssh_rportcmp_ssh1);
         /* Add port forwardings. */
        e = cfg.portfwd;
        while (*e) {
@@ -2414,13 +2455,14 @@ static void ssh1_protocol(unsigned char *in, int inlen, int ispkt)
                } else {
                    struct ssh_rportfwd *pf;
                    pf = smalloc(sizeof(*pf));
-                   strcpy(pf->host, host);
-                   pf->port = dport;
+                   strcpy(pf->dhost, host);
+                   pf->dport = dport;
                    if (add234(ssh_rportfwds, pf) != pf) {
                        sprintf(buf, 
                                "Duplicate remote port forwarding to %s:%s",
                                host, dport);
                        logevent(buf);
+                       sfree(pf);
                    } else {
                        sprintf(buf, "Requesting remote port %d forward to %s:%d",
                                sport, host, dport);
@@ -2578,8 +2620,8 @@ static void ssh1_protocol(unsigned char *in, int inlen, int ispkt)
                *h = 0;
                port = GET_32BIT(p);
 
-               strcpy(pf.host, host);
-               pf.port = port;
+               strcpy(pf.dhost, host);
+               pf.dport = port;
 
                if (find234(ssh_rportfwds, &pf, NULL) == NULL) {
                    sprintf(buf, "Rejected remote port open request for %s:%d",
@@ -2614,17 +2656,16 @@ static void ssh1_protocol(unsigned char *in, int inlen, int ispkt)
                }
 
            } else if (pktin.type == SSH1_MSG_CHANNEL_OPEN_CONFIRMATION) {
-                   unsigned int remoteid = GET_32BIT(pktin.body);
-                   unsigned int localid = GET_32BIT(pktin.body+4);
-                   struct ssh_channel *c;
-                   
-                   c = find234(ssh_channels, &remoteid, ssh_channelfind);
-                   if (c) {
-                       c->remoteid = localid;
-                       pfd_confirm(c->u.pfd.s);
-                   } else {
-                       sshfwd_close(c);
-                   }
+               unsigned int remoteid = GET_32BIT(pktin.body);
+               unsigned int localid = GET_32BIT(pktin.body+4);
+               struct ssh_channel *c;
+
+               c = find234(ssh_channels, &remoteid, ssh_channelfind);
+               if (c && c->type == CHAN_SOCKDATA_DORMANT) {
+                   c->remoteid = localid;
+                   c->type = CHAN_SOCKDATA;
+                   pfd_confirm(c->u.pfd.s);
+               }
 
            } else if (pktin.type == SSH1_MSG_CHANNEL_CLOSE ||
                       pktin.type == SSH1_MSG_CHANNEL_CLOSE_CONFIRMATION) {
@@ -2670,8 +2711,8 @@ static void ssh1_protocol(unsigned char *in, int inlen, int ispkt)
                        x11_send(c->u.x11.s, p, len);
                        break;
                      case CHAN_SOCKDATA:
-                             pfd_send(c->u.pfd.s, p, len);
-                             break;
+                       pfd_send(c->u.pfd.s, p, len);
+                       break;
                      case CHAN_AGENT:
                        /* Data for an agent message. Buffer it. */
                        while (len > 0) {
@@ -3268,18 +3309,21 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt)
 {
     static enum {
        AUTH_INVALID, AUTH_PUBLICKEY_AGENT, AUTH_PUBLICKEY_FILE,
-       AUTH_PASSWORD
+       AUTH_PASSWORD,
+        AUTH_KEYBOARD_INTERACTIVE
     } method;
     static enum {
        AUTH_TYPE_NONE,
        AUTH_TYPE_PUBLICKEY,
        AUTH_TYPE_PUBLICKEY_OFFER_LOUD,
        AUTH_TYPE_PUBLICKEY_OFFER_QUIET,
-       AUTH_TYPE_PASSWORD
+       AUTH_TYPE_PASSWORD,
+       AUTH_TYPE_KEYBOARD_INTERACTIVE
     } type;
-    static int gotit, need_pw, can_pubkey, can_passwd;
-    static int tried_pubkey_config, tried_agent;
+    static int gotit, need_pw, can_pubkey, can_passwd, can_keyb_inter;
+    static int tried_pubkey_config, tried_agent, tried_keyb_inter;
     static int we_are_in;
+    static int num_prompts, echo;
     static char username[100];
     static char pwprompt[200];
     static char password[100];
@@ -3507,10 +3551,58 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt)
                    in_commasep_string("publickey", methods, methlen);
                can_passwd =
                    in_commasep_string("password", methods, methlen);
+               can_passwd =
+                   in_commasep_string("password", methods, methlen);
+               can_keyb_inter = 
+                   in_commasep_string("keyboard-interactive", methods, methlen);
            }
 
            method = 0;
 
+           if (!method && can_keyb_inter && !tried_keyb_inter) {
+               method = AUTH_KEYBOARD_INTERACTIVE;
+               type = AUTH_TYPE_KEYBOARD_INTERACTIVE;
+               tried_keyb_inter = TRUE;
+
+               ssh2_pkt_init(SSH2_MSG_USERAUTH_REQUEST);
+               ssh2_pkt_addstring(username);
+               ssh2_pkt_addstring("ssh-connection");   /* service requested */
+               ssh2_pkt_addstring("keyboard-interactive");     /* method */
+               ssh2_pkt_addstring(""); /* lang */
+               ssh2_pkt_addstring("");
+               ssh2_pkt_send();
+
+               crWaitUntilV(ispkt);
+               if (pktin.type != SSH2_MSG_USERAUTH_INFO_REQUEST) {
+                   if (pktin.type == SSH2_MSG_USERAUTH_FAILURE)
+                       gotit = TRUE;
+                   logevent("Keyboard-interactive authentication refused");
+                   type = AUTH_TYPE_KEYBOARD_INTERACTIVE;
+                   continue;
+               }
+
+               /* We've got packet with that "interactive" info
+                  dump banners, and set its prompt as ours */
+               {
+                   char *name, *inst, *lang, *prompt;
+                   int name_len, inst_len, lang_len, prompt_len;
+                   ssh2_pkt_getstring(&name, &name_len);
+                   ssh2_pkt_getstring(&inst, &inst_len);
+                   ssh2_pkt_getstring(&lang, &lang_len);
+                   if (name_len > 0)
+                       c_write_untrusted(name, name_len);
+                   if (inst_len > 0)
+                       c_write_untrusted(inst, inst_len);
+                   num_prompts = ssh2_pkt_getuint32();
+
+                   ssh2_pkt_getstring(&prompt, &prompt_len);
+                   strncpy(pwprompt, prompt, sizeof(pwprompt));
+                   need_pw = TRUE;
+
+                   echo = ssh2_pkt_getbool();
+               }
+           }
+
            if (!method && can_pubkey && agent_exists() && !tried_agent) {
                /*
                 * Attempt public-key authentication using Pageant.
@@ -3735,7 +3827,7 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt)
                    static int pos = 0;
                    static char c;
 
-                   c_write_str(pwprompt);
+                   c_write_untrusted(pwprompt, strlen(pwprompt));
                    ssh_send_ok = 1;
 
                    pos = 0;
@@ -3896,6 +3988,13 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt)
                ssh_pkt_defersend();
                logevent("Sent password");
                type = AUTH_TYPE_PASSWORD;
+           } else if (method == AUTH_KEYBOARD_INTERACTIVE) {
+                ssh2_pkt_init(SSH2_MSG_USERAUTH_INFO_RESPONSE);
+                ssh2_pkt_adduint32(num_prompts);
+                ssh2_pkt_addstring(password);
+                memset(password, 0, sizeof(password));
+                ssh2_pkt_send();
+               type = AUTH_TYPE_KEYBOARD_INTERACTIVE;
            } else {
                c_write_str
                    ("No supported authentication methods left to try!\r\n");
@@ -3993,6 +4092,97 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt)
     }
 
     /*
+     * Enable port forwardings.
+     */
+    {
+       static char *e;                /* preserve across crReturn */
+       char type;
+       int n;
+       int sport,dport;
+       char sports[256], dports[256], host[256];
+       char buf[1024];
+
+       ssh_rportfwds = newtree234(ssh_rportcmp_ssh2);
+        /* Add port forwardings. */
+       e = cfg.portfwd;
+       while (*e) {
+           type = *e++;
+           n = 0;
+           while (*e && *e != '\t')
+               sports[n++] = *e++;
+           sports[n] = 0;
+           if (*e == '\t')
+               e++;
+           n = 0;
+           while (*e && *e != ':')
+               host[n++] = *e++;
+           host[n] = 0;
+           if (*e == ':')
+               e++;
+           n = 0;
+           while (*e)
+               dports[n++] = *e++;
+           dports[n] = 0;
+           e++;
+           dport = atoi(dports);
+           sport = atoi(sports);
+           if (sport && dport) {
+               if (type == 'L') {
+                   pfd_addforward(host, dport, sport);
+                   sprintf(buf, "Local port %d forwarding to %s:%d",
+                           sport, host, dport);
+                   logevent(buf);
+               } else {
+                   struct ssh_rportfwd *pf;
+                   pf = smalloc(sizeof(*pf));
+                   strcpy(pf->dhost, host);
+                   pf->dport = dport;
+                   pf->sport = sport;
+                   if (add234(ssh_rportfwds, pf) != pf) {
+                       sprintf(buf, 
+                               "Duplicate remote port forwarding to %s:%s",
+                               host, dport);
+                       logevent(buf);
+                       sfree(pf);
+                   } else {
+                       sprintf(buf, "Requesting remote port %d (forwarded to %s:%d)",
+                               sport, host, dport);
+                       logevent(buf);
+                       ssh2_pkt_init(SSH2_MSG_GLOBAL_REQUEST);
+                       ssh2_pkt_addstring("tcpip-forward");
+                       ssh2_pkt_addbool(1);/* want reply */
+                       ssh2_pkt_addstring("127.0.0.1");
+                       ssh2_pkt_adduint32(sport);
+                       ssh2_pkt_send();
+
+                       do {
+                           crWaitUntilV(ispkt);
+                           if (pktin.type == SSH2_MSG_CHANNEL_WINDOW_ADJUST) {
+                               unsigned i = ssh2_pkt_getuint32();
+                               struct ssh_channel *c;
+                               c = find234(ssh_channels, &i, ssh_channelfind);
+                               if (!c)
+                                   continue;/* nonexistent channel */
+                               c->v2.remwindow += ssh2_pkt_getuint32();
+                           }
+                       } while (pktin.type == SSH2_MSG_CHANNEL_WINDOW_ADJUST);
+
+                       if (pktin.type != SSH2_MSG_REQUEST_SUCCESS) {
+                           if (pktin.type != SSH2_MSG_REQUEST_FAILURE) {
+                               bombout(("Server got confused by port forwarding request"));
+                               crReturnV;
+                           }
+                           logevent("Server refused this port forwarding");
+                       } else {
+                           logevent("Remote port forwarding enabled");
+                       }
+                   }
+               }
+           }
+       }
+    }
+
+    /*
      * Potentially enable agent forwarding.
      */
     if (cfg.agentfwd && agent_exists()) {
@@ -4152,8 +4342,8 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt)
                        x11_send(c->u.x11.s, data, length);
                        break;
                      case CHAN_SOCKDATA:
-                             pfd_send(c->u.pfd.s, data, length);
-                             break;
+                       pfd_send(c->u.pfd.s, data, length);
+                       break;
                      case CHAN_AGENT:
                        while (length > 0) {
                            if (c->u.a.lensofar < 4) {
@@ -4238,8 +4428,8 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt)
                } else if (c->type == CHAN_AGENT) {
                    sshfwd_close(c);
                } else if (c->type == CHAN_SOCKDATA) {
-                       pfd_close(c->u.pfd.s);
-                       sshfwd_close(c);
+                   pfd_close(c->u.pfd.s);
+                   sshfwd_close(c);
                }
            } else if (pktin.type == SSH2_MSG_CHANNEL_CLOSE) {
                unsigned i = ssh2_pkt_getuint32();
@@ -4262,7 +4452,7 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt)
                  case CHAN_AGENT:
                    break;
                  case CHAN_SOCKDATA:
-                         break;
+                   break;
                }
                del234(ssh_channels, c);
                sfree(c->v2.outbuffer);
@@ -4290,14 +4480,35 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt)
                    continue;          /* nonexistent channel */
                c->v2.remwindow += ssh2_pkt_getuint32();
                try_send = TRUE;
+           } else if (pktin.type == SSH2_MSG_CHANNEL_OPEN_CONFIRMATION) {
+               unsigned i = ssh2_pkt_getuint32();
+               struct ssh_channel *c;
+               c = find234(ssh_channels, &i, ssh_channelfind);
+               if (!c)
+                   continue;          /* nonexistent channel */
+               if (c->type != CHAN_SOCKDATA_DORMANT)
+                   continue;          /* dunno why they're confirming this */
+               c->remoteid = ssh2_pkt_getuint32();
+               c->type = CHAN_SOCKDATA;
+               c->closes = 0;
+               c->v2.remwindow = ssh2_pkt_getuint32();
+               c->v2.remmaxpkt = ssh2_pkt_getuint32();
+               c->v2.outbuffer = NULL;
+               c->v2.outbuflen = c->v2.outbufsize = 0;
+               pfd_confirm(c->u.pfd.s);
            } else if (pktin.type == SSH2_MSG_CHANNEL_OPEN) {
                char *type;
                int typelen;
                char *error = NULL;
                struct ssh_channel *c;
+               unsigned remid, winsize, pktsize;
                ssh2_pkt_getstring(&type, &typelen);
                c = smalloc(sizeof(struct ssh_channel));
 
+               remid = ssh2_pkt_getuint32();
+               winsize = ssh2_pkt_getuint32();
+               pktsize = ssh2_pkt_getuint32();
+
                if (typelen == 3 && !memcmp(type, "x11", 3)) {
                    if (!ssh_X11_fwd_enabled)
                        error = "X11 forwarding is not enabled";
@@ -4307,6 +4518,32 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt)
                    } else {
                        c->type = CHAN_X11;
                    }
+               } else if (typelen == 15 &&
+                          !memcmp(type, "forwarded-tcpip", 15)) {
+                   struct ssh_rportfwd pf, *realpf;
+                   char *dummy;
+                   int dummylen;
+                   ssh2_pkt_getstring(&dummy, &dummylen);/* skip address */
+                   pf.sport = ssh2_pkt_getuint32();
+                   realpf = find234(ssh_rportfwds, &pf, NULL);
+                   if (realpf == NULL) {
+                       error = "Remote port is not recognised";
+                   } else {
+                       char *e = pfd_newconnect(&c->u.pfd.s, realpf->dhost,
+                                                realpf->dport, c);
+                       char buf[1024];
+                       sprintf(buf, "Received remote port open request for %s:%d",
+                               realpf->dhost, realpf->dport);
+                       logevent(buf);
+                       if (e != NULL) {
+                           sprintf(buf, "Port open failed: %s", e);
+                           logevent(buf);
+                           error = "Port open failed";
+                       } else {
+                           logevent("Forwarded port opened successfully");
+                           c->type = CHAN_SOCKDATA;
+                       }
+                   }
                } else if (typelen == 22 &&
                           !memcmp(type, "auth-agent@openssh.com", 3)) {
                    if (!ssh_agentfwd_enabled)
@@ -4319,7 +4556,7 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt)
                    error = "Unsupported channel type requested";
                }
 
-               c->remoteid = ssh2_pkt_getuint32();
+               c->remoteid = remid;
                if (error) {
                    ssh2_pkt_init(SSH2_MSG_CHANNEL_OPEN_FAILURE);
                    ssh2_pkt_adduint32(c->remoteid);
@@ -4331,8 +4568,8 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt)
                } else {
                    c->localid = alloc_channel_id();
                    c->closes = 0;
-                   c->v2.remwindow = ssh2_pkt_getuint32();
-                   c->v2.remmaxpkt = ssh2_pkt_getuint32();
+                   c->v2.remwindow = winsize;
+                   c->v2.remmaxpkt = pktsize;
                    c->v2.outbuffer = NULL;
                    c->v2.outbuflen = c->v2.outbufsize = 0;
                    add234(ssh_channels, c);
@@ -4495,10 +4732,10 @@ void *new_sock_channel(Socket s)
     c = smalloc(sizeof(struct ssh_channel));
 
     if (c) {
-       c->remoteid = GET_32BIT(pktin.body);
+       c->remoteid = -1;              /* to be set when open confirmed */
        c->localid = alloc_channel_id();
        c->closes = 0;
-       c->type = CHAN_SOCKDATA;        /* identify channel type */
+       c->type = CHAN_SOCKDATA_DORMANT;/* identify channel type */
        c->u.pfd.s = s;
        add234(ssh_channels, c);
     }
@@ -4513,12 +4750,31 @@ void ssh_send_port_open(void *channel, char *hostname, int port, char *org)
     sprintf(buf, "Opening forwarded connection to %.512s:%d", hostname, port);
     logevent(buf);
 
-    send_packet(SSH1_MSG_PORT_OPEN,
-               PKT_INT, c->localid,
-               PKT_STR, hostname,
-               PKT_INT, port,
-               //PKT_STR, org,
-               PKT_END);
+    if (ssh_version == 1) {
+       send_packet(SSH1_MSG_PORT_OPEN,
+                   PKT_INT, c->localid,
+                   PKT_STR, hostname,
+                   PKT_INT, port,
+                   //PKT_STR, <org:orgport>,
+                   PKT_END);
+    } else {
+       ssh2_pkt_init(SSH2_MSG_CHANNEL_OPEN);
+       ssh2_pkt_addstring("direct-tcpip");
+       ssh2_pkt_adduint32(c->localid);
+       ssh2_pkt_adduint32(0x8000UL);      /* our window size */
+       ssh2_pkt_adduint32(0x4000UL);      /* our max pkt size */
+       ssh2_pkt_addstring(hostname);
+       ssh2_pkt_adduint32(port);
+       /*
+        * We make up values for the originator data; partly it's
+        * too much hassle to keep track, and partly I'm not
+        * convinced the server should be told details like that
+        * about my local network configuration.
+        */
+       ssh2_pkt_addstring("client-side-connection");
+       ssh2_pkt_adduint32(0);
+       ssh2_pkt_send();
+    }
 }
 
 
@@ -4550,4 +4806,4 @@ Backend ssh_backend = {
     ssh_sendok,
     ssh_ldisc,
     22
-};
\ No newline at end of file
+};