diff options
Diffstat (limited to 'sys/netgraph/ng_mppc.c')
-rw-r--r-- | sys/netgraph/ng_mppc.c | 39 |
1 files changed, 23 insertions, 16 deletions
diff --git a/sys/netgraph/ng_mppc.c b/sys/netgraph/ng_mppc.c index 20b4bd0..6754be7 100644 --- a/sys/netgraph/ng_mppc.c +++ b/sys/netgraph/ng_mppc.c @@ -98,6 +98,15 @@ static MALLOC_DEFINE(M_NETGRAPH_MPPC, "netgraph_mppc", "netgraph mppc node"); /* Key length */ #define KEYLEN(b) (((b) & MPPE_128) ? 16 : 8) +/* + * 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 */ #define MPPC_FLAG_RESTART 0x4000 /* compress history restart */ @@ -632,22 +641,20 @@ ng_mppc_decompress(node_p node, struct mbuf **datap) #endif #ifdef NETGRAPH_MPPC_ENCRYPTION if ((d->cfg.bits & MPPE_BITS) != 0) { - u_int rekey; - - /* 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 > 1000) - log(LOG_ERR, "%s: %d packets dropped, " - "node [%x]\n", __func__, numLost, - node->nd_ID); - - /* - * When packets are lost or re-ordered with MPPE, - * we may have to re-key up to 0xfff times to 'catch - * up' to the new jumped-ahead sequence number. Yep, - * this is heavy, but what else can we do? - */ + u_int rekey; + + /* 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) != 0 || (d->cc & MPPE_UPDATE_MASK) |