Add support for stateful MPPE (microsoft encryption) providing

encryption compatibility with Windows 2000.  Stateful encryption
uses less CPU but is bad on lossy transports.

The ``set mppe'' command has been expanded.  If it's used with any
arguments, ppp will insist on encryption, closing LCP if the other
end refuses.

Unfortunately, Microsoft have abused the CCP reset request so that
receiving a reset request does not result in a reset ack when using
MPPE...

Sponsored by:	Monzoon Networks AG and FreeBSD Services Limited

1 files changed, 115 insertions, 21 deletions

diff --git a/usr.sbin/ppp/ccp.c b/usr.sbin/ppp/ccp.c
index 4e4a806..e8f0a41 100644
--- a/usr.sbin/ppp/ccp.c
+++ b/usr.sbin/ppp/ccp.c
@@ -82,7 +82,7 @@ static void CcpLayerFinish(struct fsm *);
 static int CcpLayerUp(struct fsm *);
 static void CcpLayerDown(struct fsm *);
 static void CcpInitRestartCounter(struct fsm *, int);
-static void CcpRecvResetReq(struct fsm *);
+static int CcpRecvResetReq(struct fsm *);
 static void CcpRecvResetAck(struct fsm *, u_char);
 
 static struct fsm_callbacks ccp_Callbacks = {
@@ -150,8 +150,10 @@ static const struct ccp_algorithm * const algorithm[] = {
 int
 ccp_ReportStatus(struct cmdargs const *arg)
 {
+  struct ccp_opt **o;
   struct link *l;
   struct ccp *ccp;
+  int f;
 
   l = command_ChooseLink(arg);
   ccp = &l->ccp;
@@ -166,6 +168,19 @@ ccp_ReportStatus(struct cmdargs const *arg)
                   ccp->compin, ccp->uncompin);
   }
 
+  if (ccp->in.algorithm != -1)
+    prompt_Printf(arg->prompt, "\n Input Options:  %s\n",
+                  (*algorithm[ccp->in.algorithm]->Disp)(&ccp->in.opt));
+
+  if (ccp->out.algorithm != -1) {
+    o = &ccp->out.opt;
+    for (f = 0; f < ccp->out.algorithm; f++)
+      if (IsEnabled(ccp->cfg.neg[algorithm[f]->Neg]))
+        o = &(*o)->next;
+    prompt_Printf(arg->prompt, " Output Options: %s\n",
+                  (*algorithm[ccp->out.algorithm]->Disp)(&(*o)->val));
+  }
+
   prompt_Printf(arg->prompt, "\n Defaults: ");
   prompt_Printf(arg->prompt, "FSM retry = %us, max %u Config"
                 " REQ%s, %u Term REQ%s\n", ccp->cfg.fsm.timeout,
@@ -174,16 +189,36 @@ ccp_ReportStatus(struct cmdargs const *arg)
   prompt_Printf(arg->prompt, "           deflate windows: ");
   prompt_Printf(arg->prompt, "incoming = %d, ", ccp->cfg.deflate.in.winsize);
   prompt_Printf(arg->prompt, "outgoing = %d\n", ccp->cfg.deflate.out.winsize);
-  prompt_Printf(arg->prompt, "           DEFLATE:    %s\n",
+#ifdef HAVE_DES
+  prompt_Printf(arg->prompt, "           MPPE: ");
+  if (ccp->cfg.mppe.keybits)
+    prompt_Printf(arg->prompt, "%d bits, ", ccp->cfg.mppe.keybits);
+  else
+    prompt_Printf(arg->prompt, "any bits, ");
+  switch (ccp->cfg.mppe.state) {
+  case MPPE_STATEFUL:
+    prompt_Printf(arg->prompt, "statefull");
+    break;
+  case MPPE_STATELESS:
+    prompt_Printf(arg->prompt, "stateless");
+    break;
+  case MPPE_ANYSTATE:
+    prompt_Printf(arg->prompt, "any state");
+    break;
+  }
+  prompt_Printf(arg->prompt, "%s\n",
+                ccp->cfg.mppe.required ? ", required" : "");
+#endif
+
+  prompt_Printf(arg->prompt, "\n           DEFLATE:    %s\n",
                 command_ShowNegval(ccp->cfg.neg[CCP_NEG_DEFLATE]));
   prompt_Printf(arg->prompt, "           PREDICTOR1: %s\n",
                 command_ShowNegval(ccp->cfg.neg[CCP_NEG_PRED1]));
   prompt_Printf(arg->prompt, "           DEFLATE24:  %s\n",
                 command_ShowNegval(ccp->cfg.neg[CCP_NEG_DEFLATE24]));
 #ifdef HAVE_DES
-  prompt_Printf(arg->prompt, "           MPPE:       %s",
+  prompt_Printf(arg->prompt, "           MPPE:       %s\n",
                 command_ShowNegval(ccp->cfg.neg[CCP_NEG_MPPE]));
-  prompt_Printf(arg->prompt, " (Key Size = %d-bits)\n", ccp->cfg.mppe.keybits);
 #endif
   return 0;
 }
@@ -215,7 +250,9 @@ ccp_Init(struct ccp *ccp, struct bundle *bundle, struct link *l,
   ccp->cfg.neg[CCP_NEG_PRED1] = NEG_ENABLED|NEG_ACCEPTED;
   ccp->cfg.neg[CCP_NEG_DEFLATE24] = 0;
 #ifdef HAVE_DES
-  ccp->cfg.mppe.keybits = 128;
+  ccp->cfg.mppe.keybits = 0;
+  ccp->cfg.mppe.state = MPPE_ANYSTATE;
+  ccp->cfg.mppe.required = 0;
   ccp->cfg.neg[CCP_NEG_MPPE] = NEG_ENABLED|NEG_ACCEPTED;
 #endif
 
@@ -238,6 +275,30 @@ ccp_Setup(struct ccp *ccp)
   ccp->uncompin = ccp->compin = 0;
 }
 
+/*
+ * Is ccp *REQUIRED* ?
+ * We ask each of the configured ccp protocols if they're required and
+ * return TRUE if they are.
+ *
+ * It's not possible for the peer to reject a required ccp protocol
+ * without our state machine bringing the supporting lcp layer down.
+ *
+ * If ccp is required but not open, the NCP layer should not push
+ * any data into the link.
+ */
+int
+ccp_Required(struct ccp *ccp)
+{
+  int f;
+
+  for (f = 0; f < NALGORITHMS; f++)
+    if (IsEnabled(ccp->cfg.neg[algorithm[f]->Neg]) &&
+        (*algorithm[f]->Required)(&ccp->fsm))
+      return 1;
+
+  return 0;
+}
+
 static void
 CcpInitRestartCounter(struct fsm *fp, int what)
 {
@@ -332,13 +393,14 @@ CcpSendTerminateAck(struct fsm *fp, u_char id)
   fsm_Output(fp, CODE_TERMACK, id, NULL, 0, MB_CCPOUT);
 }
 
-static void
+static int
 CcpRecvResetReq(struct fsm *fp)
 {
   /* Got a reset REQ, reset outgoing dictionary */
   struct ccp *ccp = fsm2ccp(fp);
-  if (ccp->out.state != NULL)
-    (*algorithm[ccp->out.algorithm]->o.Reset)(ccp->out.state);
+  if (ccp->out.state == NULL)
+    return 1;
+  return (*algorithm[ccp->out.algorithm]->o.Reset)(ccp->out.state);
 }
 
 static void
@@ -397,6 +459,12 @@ CcpLayerFinish(struct fsm *fp)
     free(ccp->out.opt);
     ccp->out.opt = next;
   }
+
+  if (ccp_Required(ccp)) {
+    if (fp->link->lcp.fsm.state == ST_OPENED)
+      log_Printf(LogLCP, "%s: Closing due to CCP completion\n", fp->link->name);
+    fsm_Close(&fp->link->lcp.fsm);
+  }
 }
 
 /*  Called when CCP has reached the OPEN state */
@@ -531,17 +599,28 @@ CcpDecodeConfig(struct fsm *fp, u_char *cp, int plen, int mode_type,
                      " option\n", fp->link->name);
         else {
 	  memcpy(&o->val, cp, length);
-          if ((*algorithm[f]->o.Set)(&o->val) == MODE_ACK)
+          if ((*algorithm[f]->o.Set)(&o->val, &ccp->cfg) == MODE_ACK)
             ccp->my_proto = algorithm[f]->id;
           else {
 	    ccp->his_reject |= (1 << type);
 	    ccp->my_proto = -1;
+            if (algorithm[f]->Required(fp)) {
+              log_Printf(LogWARN, "%s: Cannot understand peers (required)"
+                         " %s negotiation\n", fp->link->name,
+                         protoname(algorithm[f]->id));
+              fsm_Close(&fp->link->lcp.fsm);
+            }
           }
         }
         break;
       case MODE_REJ:
 	ccp->his_reject |= (1 << type);
 	ccp->my_proto = -1;
+        if (algorithm[f]->Required(fp)) {
+          log_Printf(LogWARN, "%s: Peer rejected (required) %s negotiation\n",
+                     fp->link->name, protoname(algorithm[f]->id));
+          fsm_Close(&fp->link->lcp.fsm);
+        }
 	break;
       }
     }
@@ -618,17 +697,26 @@ static struct mbuf *
 ccp_LayerPush(struct bundle *b, struct link *l, struct mbuf *bp,
               int pri, u_short *proto)
 {
-  if (PROTO_COMPRESSIBLE(*proto) && l->ccp.fsm.state == ST_OPENED &&
-      l->ccp.out.state != NULL) {
-    bp = (*algorithm[l->ccp.out.algorithm]->o.Write)
-           (l->ccp.out.state, &l->ccp, l, pri, proto, bp);
-    switch (*proto) {
-      case PROTO_ICOMPD:
-        m_settype(bp, MB_ICOMPDOUT);
-        break;
-      case PROTO_COMPD:
-        m_settype(bp, MB_COMPDOUT);
-        break;
+  if (PROTO_COMPRESSIBLE(*proto)) {
+    if (l->ccp.fsm.state != ST_OPENED) {
+      if (ccp_Required(&l->ccp)) {
+        /* The NCP layer shouldn't have let this happen ! */
+        log_Printf(LogERROR, "%s: Unexpected attempt to use an unopened and"
+                   " required CCP layer\n", l->name);
+        m_freem(bp);
+        bp = NULL;
+      }
+    } else if (l->ccp.out.state != NULL) {
+      bp = (*algorithm[l->ccp.out.algorithm]->o.Write)
+             (l->ccp.out.state, &l->ccp, l, pri, proto, bp);
+      switch (*proto) {
+        case PROTO_ICOMPD:
+          m_settype(bp, MB_ICOMPDOUT);
+          break;
+        case PROTO_COMPD:
+          m_settype(bp, MB_COMPDOUT);
+          break;
+      }
     }
   }
 
@@ -706,9 +794,15 @@ ccp_SetOpenMode(struct ccp *ccp)
 }
 
 int
-ccp_IsUsable(struct fsm *fp)
+ccp_DefaultUsable(struct fsm *fp)
 {
   return 1;
 }
 
+int
+ccp_DefaultRequired(struct fsm *fp)
+{
+  return 0;
+}
+
 struct layer ccplayer = { LAYER_CCP, "ccp", ccp_LayerPush, ccp_LayerPull };