diff options
Diffstat (limited to 'net/ipv4/arp.c')
| -rw-r--r-- | net/ipv4/arp.c | 48 |
1 files changed, 41 insertions, 7 deletions
diff --git a/net/ipv4/arp.c b/net/ipv4/arp.c index 0937b34c27ca..e9f3386a528b 100644 --- a/net/ipv4/arp.c +++ b/net/ipv4/arp.c @@ -641,6 +641,32 @@ void arp_xmit(struct sk_buff *skb) } EXPORT_SYMBOL(arp_xmit); +static bool arp_is_garp(struct net *net, struct net_device *dev, + int *addr_type, __be16 ar_op, + __be32 sip, __be32 tip, + unsigned char *sha, unsigned char *tha) +{ + bool is_garp = tip == sip; + + /* Gratuitous ARP _replies_ also require target hwaddr to be + * the same as source. + */ + if (is_garp && ar_op == htons(ARPOP_REPLY)) + is_garp = + /* IPv4 over IEEE 1394 doesn't provide target + * hardware address field in its ARP payload. + */ + tha && + !memcmp(tha, sha, dev->addr_len); + + if (is_garp) { + *addr_type = inet_addr_type_dev_table(net, dev, sip); + if (*addr_type != RTN_UNICAST) + is_garp = false; + } + return is_garp; +} + /* * Process an arp request. */ @@ -653,6 +679,7 @@ static int arp_process(struct net *net, struct sock *sk, struct sk_buff *skb) unsigned char *arp_ptr; struct rtable *rt; unsigned char *sha; + unsigned char *tha = NULL; __be32 sip, tip; u16 dev_type = dev->type; int addr_type; @@ -724,6 +751,7 @@ static int arp_process(struct net *net, struct sock *sk, struct sk_buff *skb) break; #endif default: + tha = arp_ptr; arp_ptr += dev->addr_len; } memcpy(&tip, arp_ptr, 4); @@ -835,19 +863,25 @@ static int arp_process(struct net *net, struct sock *sk, struct sk_buff *skb) n = __neigh_lookup(&arp_tbl, &sip, dev, 0); - if (IN_DEV_ARP_ACCEPT(in_dev)) { - unsigned int addr_type = inet_addr_type_dev_table(net, dev, sip); + addr_type = -1; + if (n || IN_DEV_ARP_ACCEPT(in_dev)) { + is_garp = arp_is_garp(net, dev, &addr_type, arp->ar_op, + sip, tip, sha, tha); + } + if (IN_DEV_ARP_ACCEPT(in_dev)) { /* Unsolicited ARP is not accepted by default. It is possible, that this option should be enabled for some devices (strip is candidate) */ - is_garp = arp->ar_op == htons(ARPOP_REQUEST) && tip == sip && - addr_type == RTN_UNICAST; - if (!n && - ((arp->ar_op == htons(ARPOP_REPLY) && - addr_type == RTN_UNICAST) || is_garp)) + (is_garp || + (arp->ar_op == htons(ARPOP_REPLY) && + (addr_type == RTN_UNICAST || + (addr_type < 0 && + /* postpone calculation to as late as possible */ + inet_addr_type_dev_table(net, dev, sip) == + RTN_UNICAST))))) n = __neigh_lookup(&arp_tbl, &sip, dev, 1); } |