#include <linux/udp.h>
#include <linux/if_vlan.h>
-/* This is the offset of the options field in a dhcp packet starting at
- * the beginning of the dhcp header
+/* These are the offsets of the "hw type" and "hw address length" in the dhcp
+ * packet starting at the beginning of the dhcp header
*/
-#define BATADV_DHCP_OPTIONS_OFFSET 240
-#define BATADV_DHCP_REQUEST 3
+#define BATADV_DHCP_HTYPE_OFFSET 1
+#define BATADV_DHCP_HLEN_OFFSET 2
+/* Value of htype representing Ethernet */
+#define BATADV_DHCP_HTYPE_ETHERNET 0x01
+/* This is the offset of the "chaddr" field in the dhcp packet starting at the
+ * beginning of the dhcp header
+ */
+#define BATADV_DHCP_CHADDR_OFFSET 28
static void batadv_gw_node_free_ref(struct batadv_gw_node *gw_node)
{
return 0;
}
-/* this call might reallocate skb data */
-static bool batadv_is_type_dhcprequest(struct sk_buff *skb, int header_len)
-{
- int ret = false;
- unsigned char *p;
- int pkt_len;
-
- if (skb_linearize(skb) < 0)
- goto out;
-
- pkt_len = skb_headlen(skb);
-
- if (pkt_len < header_len + BATADV_DHCP_OPTIONS_OFFSET + 1)
- goto out;
-
- p = skb->data + header_len + BATADV_DHCP_OPTIONS_OFFSET;
- pkt_len -= header_len + BATADV_DHCP_OPTIONS_OFFSET + 1;
-
- /* Access the dhcp option lists. Each entry is made up by:
- * - octet 1: option type
- * - octet 2: option data len (only if type != 255 and 0)
- * - octet 3: option data
- */
- while (*p != 255 && !ret) {
- /* p now points to the first octet: option type */
- if (*p == 53) {
- /* type 53 is the message type option.
- * Jump the len octet and go to the data octet
- */
- if (pkt_len < 2)
- goto out;
- p += 2;
-
- /* check if the message type is what we need */
- if (*p == BATADV_DHCP_REQUEST)
- ret = true;
- break;
- } else if (*p == 0) {
- /* option type 0 (padding), just go forward */
- if (pkt_len < 1)
- goto out;
- pkt_len--;
- p++;
- } else {
- /* This is any other option. So we get the length... */
- if (pkt_len < 1)
- goto out;
- pkt_len--;
- p++;
-
- /* ...and then we jump over the data */
- if (pkt_len < 1 + (*p))
- goto out;
- pkt_len -= 1 + (*p);
- p += 1 + (*p);
- }
- }
-out:
- return ret;
-}
-
-/* this call might reallocate skb data */
-bool batadv_gw_is_dhcp_target(struct sk_buff *skb, unsigned int *header_len)
+/**
+ * batadv_gw_dhcp_recipient_get - check if a packet is a DHCP message
+ * @skb: the packet to check
+ * @header_len: a pointer to the batman-adv header size
+ * @chaddr: buffer where the client address will be stored. Valid
+ * only if the function returns BATADV_DHCP_TO_CLIENT
+ *
+ * Returns:
+ * - BATADV_DHCP_NO if the packet is not a dhcp message or if there was an error
+ * while parsing it
+ * - BATADV_DHCP_TO_SERVER if this is a message going to the DHCP server
+ * - BATADV_DHCP_TO_CLIENT if this is a message going to a DHCP client
+ *
+ * This function may re-allocate the data buffer of the skb passed as argument.
+ */
+enum batadv_dhcp_recipient
+batadv_gw_dhcp_recipient_get(struct sk_buff *skb, unsigned int *header_len,
+ uint8_t *chaddr)
{
+ enum batadv_dhcp_recipient ret = BATADV_DHCP_NO;
struct ethhdr *ethhdr;
struct iphdr *iphdr;
struct ipv6hdr *ipv6hdr;
struct udphdr *udphdr;
struct vlan_ethhdr *vhdr;
+ int chaddr_offset;
__be16 proto;
+ uint8_t *p;
/* check for ethernet header */
if (!pskb_may_pull(skb, *header_len + ETH_HLEN))
- return false;
+ return BATADV_DHCP_NO;
+
ethhdr = (struct ethhdr *)skb->data;
proto = ethhdr->h_proto;
*header_len += ETH_HLEN;
/* check for initial vlan header */
if (proto == htons(ETH_P_8021Q)) {
if (!pskb_may_pull(skb, *header_len + VLAN_HLEN))
- return false;
+ return BATADV_DHCP_NO;
vhdr = (struct vlan_ethhdr *)skb->data;
proto = vhdr->h_vlan_encapsulated_proto;
switch (proto) {
case htons(ETH_P_IP):
if (!pskb_may_pull(skb, *header_len + sizeof(*iphdr)))
- return false;
+ return BATADV_DHCP_NO;
+
iphdr = (struct iphdr *)(skb->data + *header_len);
*header_len += iphdr->ihl * 4;
/* check for udp header */
if (iphdr->protocol != IPPROTO_UDP)
- return false;
+ return BATADV_DHCP_NO;
break;
case htons(ETH_P_IPV6):
if (!pskb_may_pull(skb, *header_len + sizeof(*ipv6hdr)))
- return false;
+ return BATADV_DHCP_NO;
+
ipv6hdr = (struct ipv6hdr *)(skb->data + *header_len);
*header_len += sizeof(*ipv6hdr);
/* check for udp header */
if (ipv6hdr->nexthdr != IPPROTO_UDP)
- return false;
+ return BATADV_DHCP_NO;
break;
default:
- return false;
+ return BATADV_DHCP_NO;
}
if (!pskb_may_pull(skb, *header_len + sizeof(*udphdr)))
- return false;
+ return BATADV_DHCP_NO;
/* skb->data might have been reallocated by pskb_may_pull() */
ethhdr = (struct ethhdr *)skb->data;
*header_len += sizeof(*udphdr);
/* check for bootp port */
- if ((proto == htons(ETH_P_IP)) &&
- (udphdr->dest != htons(67)))
- return false;
+ switch (proto) {
+ case htons(ETH_P_IP):
+ if (udphdr->dest == htons(67))
+ ret = BATADV_DHCP_TO_SERVER;
+ else if (udphdr->source == htons(67))
+ ret = BATADV_DHCP_TO_CLIENT;
+ break;
+ case htons(ETH_P_IPV6):
+ if (udphdr->dest == htons(547))
+ ret = BATADV_DHCP_TO_SERVER;
+ else if (udphdr->source == htons(547))
+ ret = BATADV_DHCP_TO_CLIENT;
+ break;
+ }
- if ((proto == htons(ETH_P_IPV6)) &&
- (udphdr->dest != htons(547)))
- return false;
+ chaddr_offset = *header_len + BATADV_DHCP_CHADDR_OFFSET;
+ /* store the client address if the message is going to a client */
+ if (ret == BATADV_DHCP_TO_CLIENT &&
+ pskb_may_pull(skb, chaddr_offset + ETH_ALEN)) {
+ /* check if the DHCP packet carries an Ethernet DHCP */
+ p = skb->data + *header_len + BATADV_DHCP_HTYPE_OFFSET;
+ if (*p != BATADV_DHCP_HTYPE_ETHERNET)
+ return BATADV_DHCP_NO;
+
+ /* check if the DHCP packet carries a valid Ethernet address */
+ p = skb->data + *header_len + BATADV_DHCP_HLEN_OFFSET;
+ if (*p != ETH_ALEN)
+ return BATADV_DHCP_NO;
+
+ memcpy(chaddr, skb->data + chaddr_offset, ETH_ALEN);
+ }
- return true;
+ return ret;
}
-
/**
* batadv_gw_out_of_range - check if the dhcp request destination is the best gw
* @bat_priv: the bat priv with all the soft interface information
* false otherwise.
*
* This call might reallocate skb data.
+ * Must be invoked only when the DHCP packet is going TO a DHCP SERVER.
*/
bool batadv_gw_out_of_range(struct batadv_priv *bat_priv,
struct sk_buff *skb)
struct batadv_neigh_node *neigh_curr = NULL, *neigh_old = NULL;
struct batadv_orig_node *orig_dst_node = NULL;
struct batadv_gw_node *gw_node = NULL, *curr_gw = NULL;
- struct ethhdr *ethhdr;
- bool ret, out_of_range = false;
- unsigned int header_len = 0;
+ struct ethhdr *ethhdr = (struct ethhdr *)skb->data;
+ bool out_of_range = false;
uint8_t curr_tq_avg;
unsigned short vid;
vid = batadv_get_vid(skb, 0);
- ret = batadv_gw_is_dhcp_target(skb, &header_len);
- if (!ret)
- goto out;
-
- ethhdr = (struct ethhdr *)skb->data;
orig_dst_node = batadv_transtable_search(bat_priv, ethhdr->h_source,
ethhdr->h_dest, vid);
if (!orig_dst_node)
if (!gw_node->bandwidth_down == 0)
goto out;
- ret = batadv_is_type_dhcprequest(skb, header_len);
- if (!ret)
- goto out;
-
switch (atomic_read(&bat_priv->gw_mode)) {
case BATADV_GW_MODE_SERVER:
/* If we are a GW then we are our best GW. We can artificially
0x00, 0x00};
static const uint8_t ectp_addr[ETH_ALEN] = {0xCF, 0x00, 0x00, 0x00,
0x00, 0x00};
+ enum batadv_dhcp_recipient dhcp_rcp = BATADV_DHCP_NO;
+ uint8_t *dst_hint = NULL, chaddr[ETH_ALEN];
struct vlan_ethhdr *vhdr;
unsigned int header_len = 0;
int data_len = skb->len, ret;
bool do_bcast = false, client_added;
unsigned short vid;
uint32_t seqno;
+ int gw_mode;
if (atomic_read(&bat_priv->mesh_state) != BATADV_MESH_ACTIVE)
goto dropped;
if (batadv_compare_eth(ethhdr->h_dest, ectp_addr))
goto dropped;
+ gw_mode = atomic_read(&bat_priv->gw_mode);
if (is_multicast_ether_addr(ethhdr->h_dest)) {
- do_bcast = true;
-
- switch (atomic_read(&bat_priv->gw_mode)) {
- case BATADV_GW_MODE_SERVER:
- /* gateway servers should not send dhcp
- * requests into the mesh
- */
- ret = batadv_gw_is_dhcp_target(skb, &header_len);
- if (ret)
- goto dropped;
- break;
- case BATADV_GW_MODE_CLIENT:
- /* gateway clients should send dhcp requests
- * via unicast to their gateway
- */
- ret = batadv_gw_is_dhcp_target(skb, &header_len);
- if (ret)
- do_bcast = false;
- break;
- case BATADV_GW_MODE_OFF:
- default:
- break;
+ /* if gw mode is off, broadcast every packet */
+ if (gw_mode == BATADV_GW_MODE_OFF) {
+ do_bcast = true;
+ goto send;
}
- /* reminder: ethhdr might have become unusable from here on
- * (batadv_gw_is_dhcp_target() might have reallocated skb data)
+ dhcp_rcp = batadv_gw_dhcp_recipient_get(skb, &header_len,
+ chaddr);
+ /* skb->data may have been modified by
+ * batadv_gw_dhcp_recipient_get()
*/
+ ethhdr = (struct ethhdr *)skb->data;
+ /* if gw_mode is on, broadcast any non-DHCP message.
+ * All the DHCP packets are going to be sent as unicast
+ */
+ if (dhcp_rcp == BATADV_DHCP_NO) {
+ do_bcast = true;
+ goto send;
+ }
+
+ if (dhcp_rcp == BATADV_DHCP_TO_CLIENT)
+ dst_hint = chaddr;
+ else if ((gw_mode == BATADV_GW_MODE_SERVER) &&
+ (dhcp_rcp == BATADV_DHCP_TO_SERVER))
+ /* gateways should not forward any DHCP message if
+ * directed to a DHCP server
+ */
+ goto dropped;
}
+send:
batadv_skb_set_priority(skb, 0);
/* ethernet packet should be broadcasted */
/* unicast packet */
} else {
- if (atomic_read(&bat_priv->gw_mode) != BATADV_GW_MODE_OFF) {
+ /* DHCP packets going to a server will use the GW feature */
+ if (dhcp_rcp == BATADV_DHCP_TO_SERVER) {
ret = batadv_gw_out_of_range(bat_priv, skb);
if (ret)
goto dropped;
- }
-
- if (batadv_dat_snoop_outgoing_arp_request(bat_priv, skb))
- goto dropped;
-
- batadv_dat_snoop_outgoing_arp_reply(bat_priv, skb);
-
- if (is_multicast_ether_addr(ethhdr->h_dest))
ret = batadv_send_skb_via_gw(bat_priv, skb, vid);
- else
- ret = batadv_send_skb_via_tt(bat_priv, skb, vid);
+ } else {
+ if (batadv_dat_snoop_outgoing_arp_request(bat_priv,
+ skb))
+ goto dropped;
+ batadv_dat_snoop_outgoing_arp_reply(bat_priv, skb);
+
+ ret = batadv_send_skb_via_tt(bat_priv, skb, dst_hint,
+ vid);
+ }
if (ret == NET_XMIT_DROP)
goto dropped_freed;
}
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