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Code Issues Releases Activity

Fix two bugs:

Browse Source 
(a) Save control message return address only if NGM_MPPC_CONFIG_DECOMP
    (b) Properly count the number of required re-key operations
	when we loose synchronization and have to resync

MFC after:	3 days
This commit is contained in:
Archie Cobbs 2002-12-14 00:56:07 +00:00
parent 3dc331b9f4
commit f3059f3906
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=107845
1 changed files with 27 additions and 12 deletions
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37
sys/netgraph/ng_mppc.c
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@ -90,8 +90,14 @@ MALLOC_DEFINE(M_NETGRAPH_MPPC, "netgraph_mppc", "netgraph mppc node ");
/* Key length */
#define KEYLEN(b) (((b) & MPPE_128) ? 16 : 8)
/* What sequence number jump is too far */
#define MPPC_INSANE_JUMP 256
/*
* When packets are lost with MPPE, we may have to re-key arbitrarily
* many times to 'catch up' to the new jumped-ahead sequence number.
* Since this can be expensive, we pose a limit on how many re-keyings
* we will do at one time to avoid a possible D.O.S. vulnerability.
* This should instead be a configurable parameter.
*/
#define MPPE_MAX_REKEY 1000
/* MPPC packet header bits */
#define MPPC_FLAG_FLUSHED 0x8000 /* xmitter reset state */
@ -261,6 +267,7 @@ ng_mppc_rcvmsg(node_p node, item_p item, hook_p lasthook)
cfg->bits = 0;
/* Save return address so we can send reset-req's */
if (!isComp)
priv->ctrlnode = NGI_RETADDR(item);
/* Configuration is OK, reset to it */
@ -566,7 +573,8 @@ ng_mppc_decompress(node_p node, struct mbuf *m, struct mbuf **resultp)
{
const priv_p priv = NG_NODE_PRIVATE(node);
struct ng_mppc_dir *const d = &priv->recv;
u_int16_t header, cc, numLost;
u_int16_t header, cc;
u_int numLost;
u_char *buf;
int len;
@ -584,13 +592,8 @@ ng_mppc_decompress(node_p node, struct mbuf *m, struct mbuf **resultp)
return (ENOMEM);
m_copydata(m, MPPC_HDRLEN, len, (caddr_t)buf);
/* Check for insane jumps in sequence numbering (D.O.S. attack) */
/* Check for an unexpected jump in the sequence number */
numLost = ((cc - d->cc) & MPPC_CCOUNT_MASK);
if (numLost >= MPPC_INSANE_JUMP) {
log(LOG_ERR, "%s: insane jump %d", __func__, numLost);
priv->recv.cfg.enable = 0;
goto failed;
}
/* If flushed bit set, we can always handle packet */
if ((header & MPPC_FLAG_FLUSHED) != 0) {
@ -600,10 +603,22 @@ ng_mppc_decompress(node_p node, struct mbuf *m, struct mbuf **resultp)
#endif
#ifdef NETGRAPH_MPPC_ENCRYPTION
if ((d->cfg.bits & MPPE_BITS) != 0) {
u_int rekey;
/* Resync as necessary, skipping lost packets */
/* How many times are we going to have to re-key? */
rekey = ((d->cfg.bits & MPPE_STATELESS) != 0) ?
numLost : (numLost / (MPPE_UPDATE_MASK + 1));
if (rekey > MPPE_MAX_REKEY) {
log(LOG_ERR, "%s: too many (%d) packets"
" dropped, disabling node %p!",
__func__, numLost, node);
priv->recv.cfg.enable = 0;
goto failed;
}
/* Re-key as necessary to catch up to peer */
while (d->cc != cc) {
if ((d->cfg.bits & MPPE_STATELESS)
if ((d->cfg.bits & MPPE_STATELESS) != 0
|| (d->cc & MPPE_UPDATE_MASK)
== MPPE_UPDATE_FLAG) {
ng_mppc_updatekey(d->cfg.bits,