// SPDX-License-Identifier: GPL-2.0
-/* Copyright (C) 2011-2018 B.A.T.M.A.N. contributors:
+/* Copyright (C) 2011-2019 B.A.T.M.A.N. contributors:
*
* Antonio Quartulli
*
#include "distributed-arp-table.h"
#include "main.h"
+#include <asm/unaligned.h>
#include <linux/atomic.h>
#include <linux/bitops.h>
#include <linux/byteorder/generic.h>
#include <linux/if_ether.h>
#include <linux/if_vlan.h>
#include <linux/in.h>
+#include <linux/ip.h>
#include <linux/jiffies.h>
#include <linux/kernel.h>
#include <linux/kref.h>
#include <linux/spinlock.h>
#include <linux/stddef.h>
#include <linux/string.h>
+#include <linux/udp.h>
#include <linux/workqueue.h>
#include <net/arp.h>
#include <net/genetlink.h>
#include "translation-table.h"
#include "tvlv.h"
+enum batadv_bootpop {
+ BATADV_BOOTREPLY = 2,
+};
+
+enum batadv_boothtype {
+ BATADV_HTYPE_ETHERNET = 1,
+};
+
+enum batadv_dhcpoptioncode {
+ BATADV_DHCP_OPT_PAD = 0,
+ BATADV_DHCP_OPT_MSG_TYPE = 53,
+ BATADV_DHCP_OPT_END = 255,
+};
+
+enum batadv_dhcptype {
+ BATADV_DHCPACK = 5,
+};
+
+/* { 99, 130, 83, 99 } */
+#define BATADV_DHCP_MAGIC 1669485411
+
+struct batadv_dhcp_packet {
+ __u8 op;
+ __u8 htype;
+ __u8 hlen;
+ __u8 hops;
+ __be32 xid;
+ __be16 secs;
+ __be16 flags;
+ __be32 ciaddr;
+ __be32 yiaddr;
+ __be32 siaddr;
+ __be32 giaddr;
+ __u8 chaddr[16];
+ __u8 sname[64];
+ __u8 file[128];
+ __be32 magic;
+ __u8 options[0];
+};
+
+#define BATADV_DHCP_YIADDR_LEN sizeof(((struct batadv_dhcp_packet *)0)->yiaddr)
+#define BATADV_DHCP_CHADDR_LEN sizeof(((struct batadv_dhcp_packet *)0)->chaddr)
+
static void batadv_dat_purge(struct work_struct *work);
/**
return dropped;
}
+/**
+ * batadv_dat_check_dhcp_ipudp() - check skb for IP+UDP headers valid for DHCP
+ * @skb: the packet to check
+ * @ip_src: a buffer to store the IPv4 source address in
+ *
+ * Checks whether the given skb has an IP and UDP header valid for a DHCP
+ * message from a DHCP server. And if so, stores the IPv4 source address in
+ * the provided buffer.
+ *
+ * Return: True if valid, false otherwise.
+ */
+static bool
+batadv_dat_check_dhcp_ipudp(struct sk_buff *skb, __be32 *ip_src)
+{
+ unsigned int offset = skb_network_offset(skb);
+ struct udphdr *udphdr, _udphdr;
+ struct iphdr *iphdr, _iphdr;
+
+ iphdr = skb_header_pointer(skb, offset, sizeof(_iphdr), &_iphdr);
+ if (!iphdr || iphdr->version != 4 || iphdr->ihl * 4 < sizeof(_iphdr))
+ return false;
+
+ if (iphdr->protocol != IPPROTO_UDP)
+ return false;
+
+ offset += iphdr->ihl * 4;
+ skb_set_transport_header(skb, offset);
+
+ udphdr = skb_header_pointer(skb, offset, sizeof(_udphdr), &_udphdr);
+ if (!udphdr || udphdr->source != htons(67))
+ return false;
+
+ *ip_src = get_unaligned(&iphdr->saddr);
+
+ return true;
+}
+
+/**
+ * batadv_dat_check_dhcp() - examine packet for valid DHCP message
+ * @skb: the packet to check
+ * @proto: ethernet protocol hint (behind a potential vlan)
+ * @ip_src: a buffer to store the IPv4 source address in
+ *
+ * Checks whether the given skb is a valid DHCP packet. And if so, stores the
+ * IPv4 source address in the provided buffer.
+ *
+ * Caller needs to ensure that the skb network header is set correctly.
+ *
+ * Return: If skb is a valid DHCP packet, then returns its op code
+ * (e.g. BOOTREPLY vs. BOOTREQUEST). Otherwise returns -EINVAL.
+ */
+static int
+batadv_dat_check_dhcp(struct sk_buff *skb, __be16 proto, __be32 *ip_src)
+{
+ __be32 *magic, _magic;
+ unsigned int offset;
+ struct {
+ __u8 op;
+ __u8 htype;
+ __u8 hlen;
+ __u8 hops;
+ } *dhcp_h, _dhcp_h;
+
+ if (proto != htons(ETH_P_IP))
+ return -EINVAL;
+
+ if (!batadv_dat_check_dhcp_ipudp(skb, ip_src))
+ return -EINVAL;
+
+ offset = skb_transport_offset(skb) + sizeof(struct udphdr);
+ if (skb->len < offset + sizeof(struct batadv_dhcp_packet))
+ return -EINVAL;
+
+ dhcp_h = skb_header_pointer(skb, offset, sizeof(_dhcp_h), &_dhcp_h);
+ if (!dhcp_h || dhcp_h->htype != BATADV_HTYPE_ETHERNET ||
+ dhcp_h->hlen != ETH_ALEN)
+ return -EINVAL;
+
+ offset += offsetof(struct batadv_dhcp_packet, magic);
+
+ magic = skb_header_pointer(skb, offset, sizeof(_magic), &_magic);
+ if (!magic || get_unaligned(magic) != htonl(BATADV_DHCP_MAGIC))
+ return -EINVAL;
+
+ return dhcp_h->op;
+}
+
+/**
+ * batadv_dat_get_dhcp_message_type() - get message type of a DHCP packet
+ * @skb: the DHCP packet to parse
+ *
+ * Iterates over the DHCP options of the given DHCP packet to find a
+ * DHCP Message Type option and parse it.
+ *
+ * Caller needs to ensure that the given skb is a valid DHCP packet and
+ * that the skb transport header is set correctly.
+ *
+ * Return: The found DHCP message type value, if found. -EINVAL otherwise.
+ */
+static int batadv_dat_get_dhcp_message_type(struct sk_buff *skb)
+{
+ unsigned int offset = skb_transport_offset(skb) + sizeof(struct udphdr);
+ u8 *type, _type;
+ struct {
+ u8 type;
+ u8 len;
+ } *tl, _tl;
+
+ offset += sizeof(struct batadv_dhcp_packet);
+
+ while ((tl = skb_header_pointer(skb, offset, sizeof(_tl), &_tl))) {
+ if (tl->type == BATADV_DHCP_OPT_MSG_TYPE)
+ break;
+
+ if (tl->type == BATADV_DHCP_OPT_END)
+ break;
+
+ if (tl->type == BATADV_DHCP_OPT_PAD)
+ offset++;
+ else
+ offset += tl->len + sizeof(_tl);
+ }
+
+ /* Option Overload Code not supported */
+ if (!tl || tl->type != BATADV_DHCP_OPT_MSG_TYPE ||
+ tl->len != sizeof(_type))
+ return -EINVAL;
+
+ offset += sizeof(_tl);
+
+ type = skb_header_pointer(skb, offset, sizeof(_type), &_type);
+ if (!type)
+ return -EINVAL;
+
+ return *type;
+}
+
+/**
+ * batadv_dat_get_dhcp_yiaddr() - get yiaddr from a DHCP packet
+ * @skb: the DHCP packet to parse
+ * @buf: a buffer to store the yiaddr in
+ *
+ * Caller needs to ensure that the given skb is a valid DHCP packet and
+ * that the skb transport header is set correctly.
+ *
+ * Return: True on success, false otherwise.
+ */
+static bool batadv_dat_dhcp_get_yiaddr(struct sk_buff *skb, __be32 *buf)
+{
+ unsigned int offset = skb_transport_offset(skb) + sizeof(struct udphdr);
+ __be32 *yiaddr;
+
+ offset += offsetof(struct batadv_dhcp_packet, yiaddr);
+ yiaddr = skb_header_pointer(skb, offset, BATADV_DHCP_YIADDR_LEN, buf);
+
+ if (!yiaddr)
+ return false;
+
+ if (yiaddr != buf)
+ *buf = get_unaligned(yiaddr);
+
+ return true;
+}
+
+/**
+ * batadv_dat_get_dhcp_chaddr() - get chaddr from a DHCP packet
+ * @skb: the DHCP packet to parse
+ * @buf: a buffer to store the chaddr in
+ *
+ * Caller needs to ensure that the given skb is a valid DHCP packet and
+ * that the skb transport header is set correctly.
+ *
+ * Return: True on success, false otherwise
+ */
+static bool batadv_dat_get_dhcp_chaddr(struct sk_buff *skb, u8 *buf)
+{
+ unsigned int offset = skb_transport_offset(skb) + sizeof(struct udphdr);
+ u8 *chaddr;
+
+ offset += offsetof(struct batadv_dhcp_packet, chaddr);
+ chaddr = skb_header_pointer(skb, offset, BATADV_DHCP_CHADDR_LEN, buf);
+
+ if (!chaddr)
+ return false;
+
+ if (chaddr != buf)
+ memcpy(buf, chaddr, BATADV_DHCP_CHADDR_LEN);
+
+ return true;
+}
+
+/**
+ * batadv_dat_put_dhcp() - puts addresses from a DHCP packet into the DHT and
+ * DAT cache
+ * @bat_priv: the bat priv with all the soft interface information
+ * @chaddr: the DHCP client MAC address
+ * @yiaddr: the DHCP client IP address
+ * @hw_dst: the DHCP server MAC address
+ * @ip_dst: the DHCP server IP address
+ * @vid: VLAN identifier
+ *
+ * Adds given MAC/IP pairs to the local DAT cache and propagates them further
+ * into the DHT.
+ *
+ * For the DHT propagation, client MAC + IP will appear as the ARP Reply
+ * transmitter (and hw_dst/ip_dst as the target).
+ */
+static void batadv_dat_put_dhcp(struct batadv_priv *bat_priv, u8 *chaddr,
+ __be32 yiaddr, u8 *hw_dst, __be32 ip_dst,
+ unsigned short vid)
+{
+ struct sk_buff *skb;
+
+ skb = batadv_dat_arp_create_reply(bat_priv, yiaddr, ip_dst, chaddr,
+ hw_dst, vid);
+ if (!skb)
+ return;
+
+ skb_set_network_header(skb, ETH_HLEN);
+
+ batadv_dat_entry_add(bat_priv, yiaddr, chaddr, vid);
+ batadv_dat_entry_add(bat_priv, ip_dst, hw_dst, vid);
+
+ batadv_dat_send_data(bat_priv, skb, yiaddr, vid, BATADV_P_DAT_DHT_PUT);
+ batadv_dat_send_data(bat_priv, skb, ip_dst, vid, BATADV_P_DAT_DHT_PUT);
+
+ batadv_dbg(BATADV_DBG_DAT, bat_priv,
+ "Snooped from outgoing DHCPACK (server address): %pI4, %pM (vid: %i)\n",
+ &ip_dst, hw_dst, batadv_print_vid(vid));
+ batadv_dbg(BATADV_DBG_DAT, bat_priv,
+ "Snooped from outgoing DHCPACK (client address): %pI4, %pM (vid: %i)\n",
+ &yiaddr, chaddr, batadv_print_vid(vid));
+}
+
+/**
+ * batadv_dat_check_dhcp_ack() - examine packet for valid DHCP message
+ * @skb: the packet to check
+ * @proto: ethernet protocol hint (behind a potential vlan)
+ * @ip_src: a buffer to store the IPv4 source address in
+ * @chaddr: a buffer to store the DHCP Client Hardware Address in
+ * @yiaddr: a buffer to store the DHCP Your IP Address in
+ *
+ * Checks whether the given skb is a valid DHCPACK. And if so, stores the
+ * IPv4 server source address (ip_src), client MAC address (chaddr) and client
+ * IPv4 address (yiaddr) in the provided buffers.
+ *
+ * Caller needs to ensure that the skb network header is set correctly.
+ *
+ * Return: True if the skb is a valid DHCPACK. False otherwise.
+ */
+static bool
+batadv_dat_check_dhcp_ack(struct sk_buff *skb, __be16 proto, __be32 *ip_src,
+ u8 *chaddr, __be32 *yiaddr)
+{
+ int type;
+
+ type = batadv_dat_check_dhcp(skb, proto, ip_src);
+ if (type != BATADV_BOOTREPLY)
+ return false;
+
+ type = batadv_dat_get_dhcp_message_type(skb);
+ if (type != BATADV_DHCPACK)
+ return false;
+
+ if (!batadv_dat_dhcp_get_yiaddr(skb, yiaddr))
+ return false;
+
+ if (!batadv_dat_get_dhcp_chaddr(skb, chaddr))
+ return false;
+
+ return true;
+}
+
+/**
+ * batadv_dat_snoop_outgoing_dhcp_ack() - snoop DHCPACK and fill DAT with it
+ * @bat_priv: the bat priv with all the soft interface information
+ * @skb: the packet to snoop
+ * @proto: ethernet protocol hint (behind a potential vlan)
+ * @vid: VLAN identifier
+ *
+ * This function first checks whether the given skb is a valid DHCPACK. If
+ * so then its source MAC and IP as well as its DHCP Client Hardware Address
+ * field and DHCP Your IP Address field are added to the local DAT cache and
+ * propagated into the DHT.
+ *
+ * Caller needs to ensure that the skb mac and network headers are set
+ * correctly.
+ */
+void batadv_dat_snoop_outgoing_dhcp_ack(struct batadv_priv *bat_priv,
+ struct sk_buff *skb,
+ __be16 proto,
+ unsigned short vid)
+{
+ u8 chaddr[BATADV_DHCP_CHADDR_LEN];
+ __be32 ip_src, yiaddr;
+
+ if (!atomic_read(&bat_priv->distributed_arp_table))
+ return;
+
+ if (!batadv_dat_check_dhcp_ack(skb, proto, &ip_src, chaddr, &yiaddr))
+ return;
+
+ batadv_dat_put_dhcp(bat_priv, chaddr, yiaddr, eth_hdr(skb)->h_source,
+ ip_src, vid);
+}
+
+/**
+ * batadv_dat_snoop_incoming_dhcp_ack() - snoop DHCPACK and fill DAT cache
+ * @bat_priv: the bat priv with all the soft interface information
+ * @skb: the packet to snoop
+ * @hdr_size: header size, up to the tail of the batman-adv header
+ *
+ * This function first checks whether the given skb is a valid DHCPACK. If
+ * so then its source MAC and IP as well as its DHCP Client Hardware Address
+ * field and DHCP Your IP Address field are added to the local DAT cache.
+ */
+void batadv_dat_snoop_incoming_dhcp_ack(struct batadv_priv *bat_priv,
+ struct sk_buff *skb, int hdr_size)
+{
+ u8 chaddr[BATADV_DHCP_CHADDR_LEN];
+ struct ethhdr *ethhdr;
+ __be32 ip_src, yiaddr;
+ unsigned short vid;
+ __be16 proto;
+ u8 *hw_src;
+
+ if (!atomic_read(&bat_priv->distributed_arp_table))
+ return;
+
+ if (unlikely(!pskb_may_pull(skb, hdr_size + ETH_HLEN)))
+ return;
+
+ ethhdr = (struct ethhdr *)(skb->data + hdr_size);
+ skb_set_network_header(skb, hdr_size + ETH_HLEN);
+ proto = ethhdr->h_proto;
+
+ if (!batadv_dat_check_dhcp_ack(skb, proto, &ip_src, chaddr, &yiaddr))
+ return;
+
+ hw_src = ethhdr->h_source;
+ vid = batadv_dat_get_vid(skb, &hdr_size);
+
+ batadv_dat_entry_add(bat_priv, yiaddr, chaddr, vid);
+ batadv_dat_entry_add(bat_priv, ip_src, hw_src, vid);
+
+ batadv_dbg(BATADV_DBG_DAT, bat_priv,
+ "Snooped from incoming DHCPACK (server address): %pI4, %pM (vid: %i)\n",
+ &ip_src, hw_src, batadv_print_vid(vid));
+ batadv_dbg(BATADV_DBG_DAT, bat_priv,
+ "Snooped from incoming DHCPACK (client address): %pI4, %pM (vid: %i)\n",
+ &yiaddr, chaddr, batadv_print_vid(vid));
+}
+
/**
* batadv_dat_drop_broadcast_packet() - check if an ARP request has to be
* dropped (because the node has already obtained the reply via DAT) or not
git.samba.org / sfrench / cifs-2.6.git / commitdiff