Attachment 155154 Details for Bug 199144 – patch

[patch] patch

patch-ppp-mppe.c (text/plain), 2.73 KB, created by Alexander Zagrebin on 2015-04-03 10:19:33 UTC

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Creator: Alexander Zagrebin

Created: 2015-04-03 10:19:33 UTC

Size: 2.73 KB

patch

obsolete

>--- mppe.c.orig	2014-07-06 19:27:29.899279626 +0400
>+++ mppe.c	2015-04-02 13:22:06.787417572 +0300
>@@ -92,6 +92,7 @@
> #define	MPPE_HEADER_FLAGMASK		0x00ff
> #define	MPPE_HEADER_FLAGSHIFT		8
> #define	MPPE_HEADER_STATEFUL_KEYCHANGES	16
>+#define	MPPE_KEY_HISTORY_SIZE		64	/* Have to be power of 2 */
> 
> struct mppe_state {
>   unsigned	stateless : 1;
>@@ -103,6 +104,7 @@ struct mppe_state {
>   char		sesskey[MPPE_KEY_LEN];
>   char		mastkey[MPPE_KEY_LEN];
>   RC4_KEY	rc4key;
>+  char		(*sesskeyhistory)[MPPE_KEY_LEN];
> };
> 
> int MPPE_MasterKeyValid = 0;
>@@ -152,6 +154,11 @@ MPPEKeyChange(struct mppe_state *mp)
>   RC4(&RC4Key, mp->keylen, InterimKey, mp->sesskey);
> 
>   MPPEReduceSessionKey(mp);
>+
>+  if (mp->sesskeyhistory) {
>+    memcpy(mp->sesskeyhistory[(mp->cohnum + 1) % MPPE_KEY_HISTORY_SIZE],
>+      mp->sesskey, MPPE_KEY_LEN);
>+  }
> }
> 
> static struct mbuf *
>@@ -273,6 +280,22 @@ MPPEInput(void *v, struct ccp *ccp, u_sh
>   }
> 
>   if (mip->stateless) {
>+    int cohnumchange = (prefix - mip->cohnum) & 0xfff;
>+    if (cohnumchange > 2047) {
>+      /* We're assuming that coherency number went backward; delayed packet. */
>+      log_Printf(LogDEBUG, "MPPEInput: Delayed packet recieved (coherency count is %d instead of %d)\n",
>+          prefix, mip->cohnum + 1);
>+      if (!mip->sesskeyhistory || (4096 - cohnumchange > MPPE_KEY_HISTORY_SIZE - 1)) {
>+        log_Printf(LogCCP, "MPPEInput: Required key is absent in the history - packet discarded\n");
>+        m_freem(mp);
>+        return NULL;
>+      }
>+      log_Printf(LogDEBUG, "MPPEInput: Using key from history for decryption\n");
>+      RC4_set_key(&mip->rc4key, mip->keylen, mip->sesskeyhistory[prefix % MPPE_KEY_HISTORY_SIZE]);
>+    } else {
>+      if (cohnumchange > 1)
>+        log_Printf(LogDEBUG, "MPPEInput: %d packet(s) missed (coherency count is %d instead of %d)\n",
>+          cohnumchange - 1, prefix, (mip->cohnum + 1) & 0xfff);
>     /* Change our key for each missed packet in stateless mode */
>     while (prefix != mip->cohnum) {
>       log_Printf(LogDEBUG, "MPPEInput: Key changed [%u]\n", prefix);
>@@ -285,6 +308,7 @@ MPPEInput(void *v, struct ccp *ccp, u_sh
>       mip->cohnum &= ~MPPE_HEADER_BITMASK;
>     }
>     dictinit = 1;
>+    }
>   } else {
>     if (flushed) {
>       /*
>@@ -724,6 +748,7 @@ MPPEInitInput(struct bundle *bundle __un
>      * to have a sequence number of 0 and we'll therefore not expect
>      * to have to change the key at that point.
>      */
>+    mip->sesskeyhistory = malloc(MPPE_KEY_HISTORY_SIZE * MPPE_KEY_LEN);
>     log_Printf(LogDEBUG, "MPPEInitInput: Key changed [%d]\n", mip->cohnum);
>     MPPEKeyChange(mip);
>   }
>@@ -782,6 +807,7 @@ MPPEInitOutput(struct bundle *bundle __u
> static void
> MPPETermInput(void *v)
> {
>+  free(((struct mppe_state *) v)->sesskeyhistory);
>   free(v);
> }
>

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Attachments on bug 199144: 155154