From faf7d36e5ecd16ab090c82d14bff31f7ab2f70e6 Mon Sep 17 00:00:00 2001 From: Alexander Aring Date: Wed, 2 Sep 2015 14:21:26 +0200 Subject: [PATCH] ieee802154: 6lowpan: add generic lowpan header check This patch introduce an earlier check if a 6LoWPAN frame can be valid. This contains at first for checking if the header contains a dispatch byte and isn't the nalp dispatch value, which means it isn't a 6LoWPAN packet. Also we add a check if we can derference the dispatch value by checking if skb->len is unequal zero. Reviewed-by: Stefan Schmidt Signed-off-by: Alexander Aring Signed-off-by: Marcel Holtmann --- net/ieee802154/6lowpan/rx.c | 28 +++++++++++++++++++++++++++- 1 file changed, 27 insertions(+), 1 deletion(-) diff --git a/net/ieee802154/6lowpan/rx.c b/net/ieee802154/6lowpan/rx.c index fded1099fae0..c46cab3b0ff4 100644 --- a/net/ieee802154/6lowpan/rx.c +++ b/net/ieee802154/6lowpan/rx.c @@ -15,8 +15,11 @@ #include "6lowpan_i.h" +#define LOWPAN_DISPATCH_FIRST 0xc0 #define LOWPAN_DISPATCH_FRAG_MASK 0xf8 +#define LOWPAN_DISPATCH_NALP 0x00 + static int lowpan_give_skb_to_device(struct sk_buff *skb) { skb->protocol = htons(ETH_P_IPV6); @@ -162,13 +165,36 @@ static int lowpan_invoke_rx_handlers(struct sk_buff *skb) #undef CALL_RXH } +static inline bool lowpan_is_nalp(u8 dispatch) +{ + return (dispatch & LOWPAN_DISPATCH_FIRST) == LOWPAN_DISPATCH_NALP; +} + +/* lowpan_rx_h_check checks on generic 6LoWPAN requirements + * in MAC and 6LoWPAN header. + * + * Don't manipulate the skb here, it could be shared buffer. + */ +static inline bool lowpan_rx_h_check(struct sk_buff *skb) +{ + /* check if we can dereference the dispatch */ + if (unlikely(!skb->len)) + return false; + + if (lowpan_is_nalp(*skb_network_header(skb))) + return false; + + return true; +} + static int lowpan_rcv(struct sk_buff *skb, struct net_device *wdev, struct packet_type *pt, struct net_device *orig_wdev) { struct net_device *ldev; if (wdev->type != ARPHRD_IEEE802154 || - skb->pkt_type == PACKET_OTHERHOST) + skb->pkt_type == PACKET_OTHERHOST || + !lowpan_rx_h_check(skb)) return NET_RX_DROP; ldev = wdev->ieee802154_ptr->lowpan_dev;