mirror of https://gitee.com/openkylin/linux.git
561 lines
16 KiB
C
561 lines
16 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
/* Copyright (C) 2013-2019 B.A.T.M.A.N. contributors:
|
|
*
|
|
* Martin Hundebøll <martin@hundeboll.net>
|
|
*
|
|
* This program is free software; you can redistribute it and/or
|
|
* modify it under the terms of version 2 of the GNU General Public
|
|
* License as published by the Free Software Foundation.
|
|
*
|
|
* This program is distributed in the hope that it will be useful, but
|
|
* WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
* General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License
|
|
* along with this program; if not, see <http://www.gnu.org/licenses/>.
|
|
*/
|
|
|
|
#include "fragmentation.h"
|
|
#include "main.h"
|
|
|
|
#include <linux/atomic.h>
|
|
#include <linux/byteorder/generic.h>
|
|
#include <linux/errno.h>
|
|
#include <linux/etherdevice.h>
|
|
#include <linux/gfp.h>
|
|
#include <linux/if_ether.h>
|
|
#include <linux/jiffies.h>
|
|
#include <linux/kernel.h>
|
|
#include <linux/lockdep.h>
|
|
#include <linux/netdevice.h>
|
|
#include <linux/skbuff.h>
|
|
#include <linux/slab.h>
|
|
#include <linux/spinlock.h>
|
|
#include <linux/string.h>
|
|
#include <uapi/linux/batadv_packet.h>
|
|
|
|
#include "hard-interface.h"
|
|
#include "originator.h"
|
|
#include "routing.h"
|
|
#include "send.h"
|
|
#include "soft-interface.h"
|
|
|
|
/**
|
|
* batadv_frag_clear_chain() - delete entries in the fragment buffer chain
|
|
* @head: head of chain with entries.
|
|
* @dropped: whether the chain is cleared because all fragments are dropped
|
|
*
|
|
* Free fragments in the passed hlist. Should be called with appropriate lock.
|
|
*/
|
|
static void batadv_frag_clear_chain(struct hlist_head *head, bool dropped)
|
|
{
|
|
struct batadv_frag_list_entry *entry;
|
|
struct hlist_node *node;
|
|
|
|
hlist_for_each_entry_safe(entry, node, head, list) {
|
|
hlist_del(&entry->list);
|
|
|
|
if (dropped)
|
|
kfree_skb(entry->skb);
|
|
else
|
|
consume_skb(entry->skb);
|
|
|
|
kfree(entry);
|
|
}
|
|
}
|
|
|
|
/**
|
|
* batadv_frag_purge_orig() - free fragments associated to an orig
|
|
* @orig_node: originator to free fragments from
|
|
* @check_cb: optional function to tell if an entry should be purged
|
|
*/
|
|
void batadv_frag_purge_orig(struct batadv_orig_node *orig_node,
|
|
bool (*check_cb)(struct batadv_frag_table_entry *))
|
|
{
|
|
struct batadv_frag_table_entry *chain;
|
|
u8 i;
|
|
|
|
for (i = 0; i < BATADV_FRAG_BUFFER_COUNT; i++) {
|
|
chain = &orig_node->fragments[i];
|
|
spin_lock_bh(&chain->lock);
|
|
|
|
if (!check_cb || check_cb(chain)) {
|
|
batadv_frag_clear_chain(&chain->fragment_list, true);
|
|
chain->size = 0;
|
|
}
|
|
|
|
spin_unlock_bh(&chain->lock);
|
|
}
|
|
}
|
|
|
|
/**
|
|
* batadv_frag_size_limit() - maximum possible size of packet to be fragmented
|
|
*
|
|
* Return: the maximum size of payload that can be fragmented.
|
|
*/
|
|
static int batadv_frag_size_limit(void)
|
|
{
|
|
int limit = BATADV_FRAG_MAX_FRAG_SIZE;
|
|
|
|
limit -= sizeof(struct batadv_frag_packet);
|
|
limit *= BATADV_FRAG_MAX_FRAGMENTS;
|
|
|
|
return limit;
|
|
}
|
|
|
|
/**
|
|
* batadv_frag_init_chain() - check and prepare fragment chain for new fragment
|
|
* @chain: chain in fragments table to init
|
|
* @seqno: sequence number of the received fragment
|
|
*
|
|
* Make chain ready for a fragment with sequence number "seqno". Delete existing
|
|
* entries if they have an "old" sequence number.
|
|
*
|
|
* Caller must hold chain->lock.
|
|
*
|
|
* Return: true if chain is empty and caller can just insert the new fragment
|
|
* without searching for the right position.
|
|
*/
|
|
static bool batadv_frag_init_chain(struct batadv_frag_table_entry *chain,
|
|
u16 seqno)
|
|
{
|
|
lockdep_assert_held(&chain->lock);
|
|
|
|
if (chain->seqno == seqno)
|
|
return false;
|
|
|
|
if (!hlist_empty(&chain->fragment_list))
|
|
batadv_frag_clear_chain(&chain->fragment_list, true);
|
|
|
|
chain->size = 0;
|
|
chain->seqno = seqno;
|
|
|
|
return true;
|
|
}
|
|
|
|
/**
|
|
* batadv_frag_insert_packet() - insert a fragment into a fragment chain
|
|
* @orig_node: originator that the fragment was received from
|
|
* @skb: skb to insert
|
|
* @chain_out: list head to attach complete chains of fragments to
|
|
*
|
|
* Insert a new fragment into the reverse ordered chain in the right table
|
|
* entry. The hash table entry is cleared if "old" fragments exist in it.
|
|
*
|
|
* Return: true if skb is buffered, false on error. If the chain has all the
|
|
* fragments needed to merge the packet, the chain is moved to the passed head
|
|
* to avoid locking the chain in the table.
|
|
*/
|
|
static bool batadv_frag_insert_packet(struct batadv_orig_node *orig_node,
|
|
struct sk_buff *skb,
|
|
struct hlist_head *chain_out)
|
|
{
|
|
struct batadv_frag_table_entry *chain;
|
|
struct batadv_frag_list_entry *frag_entry_new = NULL, *frag_entry_curr;
|
|
struct batadv_frag_list_entry *frag_entry_last = NULL;
|
|
struct batadv_frag_packet *frag_packet;
|
|
u8 bucket;
|
|
u16 seqno, hdr_size = sizeof(struct batadv_frag_packet);
|
|
bool ret = false;
|
|
|
|
/* Linearize packet to avoid linearizing 16 packets in a row when doing
|
|
* the later merge. Non-linear merge should be added to remove this
|
|
* linearization.
|
|
*/
|
|
if (skb_linearize(skb) < 0)
|
|
goto err;
|
|
|
|
frag_packet = (struct batadv_frag_packet *)skb->data;
|
|
seqno = ntohs(frag_packet->seqno);
|
|
bucket = seqno % BATADV_FRAG_BUFFER_COUNT;
|
|
|
|
frag_entry_new = kmalloc(sizeof(*frag_entry_new), GFP_ATOMIC);
|
|
if (!frag_entry_new)
|
|
goto err;
|
|
|
|
frag_entry_new->skb = skb;
|
|
frag_entry_new->no = frag_packet->no;
|
|
|
|
/* Select entry in the "chain table" and delete any prior fragments
|
|
* with another sequence number. batadv_frag_init_chain() returns true,
|
|
* if the list is empty at return.
|
|
*/
|
|
chain = &orig_node->fragments[bucket];
|
|
spin_lock_bh(&chain->lock);
|
|
if (batadv_frag_init_chain(chain, seqno)) {
|
|
hlist_add_head(&frag_entry_new->list, &chain->fragment_list);
|
|
chain->size = skb->len - hdr_size;
|
|
chain->timestamp = jiffies;
|
|
chain->total_size = ntohs(frag_packet->total_size);
|
|
ret = true;
|
|
goto out;
|
|
}
|
|
|
|
/* Find the position for the new fragment. */
|
|
hlist_for_each_entry(frag_entry_curr, &chain->fragment_list, list) {
|
|
/* Drop packet if fragment already exists. */
|
|
if (frag_entry_curr->no == frag_entry_new->no)
|
|
goto err_unlock;
|
|
|
|
/* Order fragments from highest to lowest. */
|
|
if (frag_entry_curr->no < frag_entry_new->no) {
|
|
hlist_add_before(&frag_entry_new->list,
|
|
&frag_entry_curr->list);
|
|
chain->size += skb->len - hdr_size;
|
|
chain->timestamp = jiffies;
|
|
ret = true;
|
|
goto out;
|
|
}
|
|
|
|
/* store current entry because it could be the last in list */
|
|
frag_entry_last = frag_entry_curr;
|
|
}
|
|
|
|
/* Reached the end of the list, so insert after 'frag_entry_last'. */
|
|
if (likely(frag_entry_last)) {
|
|
hlist_add_behind(&frag_entry_new->list, &frag_entry_last->list);
|
|
chain->size += skb->len - hdr_size;
|
|
chain->timestamp = jiffies;
|
|
ret = true;
|
|
}
|
|
|
|
out:
|
|
if (chain->size > batadv_frag_size_limit() ||
|
|
chain->total_size != ntohs(frag_packet->total_size) ||
|
|
chain->total_size > batadv_frag_size_limit()) {
|
|
/* Clear chain if total size of either the list or the packet
|
|
* exceeds the maximum size of one merged packet. Don't allow
|
|
* packets to have different total_size.
|
|
*/
|
|
batadv_frag_clear_chain(&chain->fragment_list, true);
|
|
chain->size = 0;
|
|
} else if (ntohs(frag_packet->total_size) == chain->size) {
|
|
/* All fragments received. Hand over chain to caller. */
|
|
hlist_move_list(&chain->fragment_list, chain_out);
|
|
chain->size = 0;
|
|
}
|
|
|
|
err_unlock:
|
|
spin_unlock_bh(&chain->lock);
|
|
|
|
err:
|
|
if (!ret) {
|
|
kfree(frag_entry_new);
|
|
kfree_skb(skb);
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* batadv_frag_merge_packets() - merge a chain of fragments
|
|
* @chain: head of chain with fragments
|
|
*
|
|
* Expand the first skb in the chain and copy the content of the remaining
|
|
* skb's into the expanded one. After doing so, clear the chain.
|
|
*
|
|
* Return: the merged skb or NULL on error.
|
|
*/
|
|
static struct sk_buff *
|
|
batadv_frag_merge_packets(struct hlist_head *chain)
|
|
{
|
|
struct batadv_frag_packet *packet;
|
|
struct batadv_frag_list_entry *entry;
|
|
struct sk_buff *skb_out;
|
|
int size, hdr_size = sizeof(struct batadv_frag_packet);
|
|
bool dropped = false;
|
|
|
|
/* Remove first entry, as this is the destination for the rest of the
|
|
* fragments.
|
|
*/
|
|
entry = hlist_entry(chain->first, struct batadv_frag_list_entry, list);
|
|
hlist_del(&entry->list);
|
|
skb_out = entry->skb;
|
|
kfree(entry);
|
|
|
|
packet = (struct batadv_frag_packet *)skb_out->data;
|
|
size = ntohs(packet->total_size) + hdr_size;
|
|
|
|
/* Make room for the rest of the fragments. */
|
|
if (pskb_expand_head(skb_out, 0, size - skb_out->len, GFP_ATOMIC) < 0) {
|
|
kfree_skb(skb_out);
|
|
skb_out = NULL;
|
|
dropped = true;
|
|
goto free;
|
|
}
|
|
|
|
/* Move the existing MAC header to just before the payload. (Override
|
|
* the fragment header.)
|
|
*/
|
|
skb_pull(skb_out, hdr_size);
|
|
skb_out->ip_summed = CHECKSUM_NONE;
|
|
memmove(skb_out->data - ETH_HLEN, skb_mac_header(skb_out), ETH_HLEN);
|
|
skb_set_mac_header(skb_out, -ETH_HLEN);
|
|
skb_reset_network_header(skb_out);
|
|
skb_reset_transport_header(skb_out);
|
|
|
|
/* Copy the payload of the each fragment into the last skb */
|
|
hlist_for_each_entry(entry, chain, list) {
|
|
size = entry->skb->len - hdr_size;
|
|
skb_put_data(skb_out, entry->skb->data + hdr_size, size);
|
|
}
|
|
|
|
free:
|
|
/* Locking is not needed, because 'chain' is not part of any orig. */
|
|
batadv_frag_clear_chain(chain, dropped);
|
|
return skb_out;
|
|
}
|
|
|
|
/**
|
|
* batadv_frag_skb_buffer() - buffer fragment for later merge
|
|
* @skb: skb to buffer
|
|
* @orig_node_src: originator that the skb is received from
|
|
*
|
|
* Add fragment to buffer and merge fragments if possible.
|
|
*
|
|
* There are three possible outcomes: 1) Packet is merged: Return true and
|
|
* set *skb to merged packet; 2) Packet is buffered: Return true and set *skb
|
|
* to NULL; 3) Error: Return false and free skb.
|
|
*
|
|
* Return: true when packet is merged or buffered, false when skb is not not
|
|
* used.
|
|
*/
|
|
bool batadv_frag_skb_buffer(struct sk_buff **skb,
|
|
struct batadv_orig_node *orig_node_src)
|
|
{
|
|
struct sk_buff *skb_out = NULL;
|
|
struct hlist_head head = HLIST_HEAD_INIT;
|
|
bool ret = false;
|
|
|
|
/* Add packet to buffer and table entry if merge is possible. */
|
|
if (!batadv_frag_insert_packet(orig_node_src, *skb, &head))
|
|
goto out_err;
|
|
|
|
/* Leave if more fragments are needed to merge. */
|
|
if (hlist_empty(&head))
|
|
goto out;
|
|
|
|
skb_out = batadv_frag_merge_packets(&head);
|
|
if (!skb_out)
|
|
goto out_err;
|
|
|
|
out:
|
|
ret = true;
|
|
out_err:
|
|
*skb = skb_out;
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* batadv_frag_skb_fwd() - forward fragments that would exceed MTU when merged
|
|
* @skb: skb to forward
|
|
* @recv_if: interface that the skb is received on
|
|
* @orig_node_src: originator that the skb is received from
|
|
*
|
|
* Look up the next-hop of the fragments payload and check if the merged packet
|
|
* will exceed the MTU towards the next-hop. If so, the fragment is forwarded
|
|
* without merging it.
|
|
*
|
|
* Return: true if the fragment is consumed/forwarded, false otherwise.
|
|
*/
|
|
bool batadv_frag_skb_fwd(struct sk_buff *skb,
|
|
struct batadv_hard_iface *recv_if,
|
|
struct batadv_orig_node *orig_node_src)
|
|
{
|
|
struct batadv_priv *bat_priv = netdev_priv(recv_if->soft_iface);
|
|
struct batadv_orig_node *orig_node_dst;
|
|
struct batadv_neigh_node *neigh_node = NULL;
|
|
struct batadv_frag_packet *packet;
|
|
u16 total_size;
|
|
bool ret = false;
|
|
|
|
packet = (struct batadv_frag_packet *)skb->data;
|
|
orig_node_dst = batadv_orig_hash_find(bat_priv, packet->dest);
|
|
if (!orig_node_dst)
|
|
goto out;
|
|
|
|
neigh_node = batadv_find_router(bat_priv, orig_node_dst, recv_if);
|
|
if (!neigh_node)
|
|
goto out;
|
|
|
|
/* Forward the fragment, if the merged packet would be too big to
|
|
* be assembled.
|
|
*/
|
|
total_size = ntohs(packet->total_size);
|
|
if (total_size > neigh_node->if_incoming->net_dev->mtu) {
|
|
batadv_inc_counter(bat_priv, BATADV_CNT_FRAG_FWD);
|
|
batadv_add_counter(bat_priv, BATADV_CNT_FRAG_FWD_BYTES,
|
|
skb->len + ETH_HLEN);
|
|
|
|
packet->ttl--;
|
|
batadv_send_unicast_skb(skb, neigh_node);
|
|
ret = true;
|
|
}
|
|
|
|
out:
|
|
if (orig_node_dst)
|
|
batadv_orig_node_put(orig_node_dst);
|
|
if (neigh_node)
|
|
batadv_neigh_node_put(neigh_node);
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* batadv_frag_create() - create a fragment from skb
|
|
* @skb: skb to create fragment from
|
|
* @frag_head: header to use in new fragment
|
|
* @fragment_size: size of new fragment
|
|
*
|
|
* Split the passed skb into two fragments: A new one with size matching the
|
|
* passed mtu and the old one with the rest. The new skb contains data from the
|
|
* tail of the old skb.
|
|
*
|
|
* Return: the new fragment, NULL on error.
|
|
*/
|
|
static struct sk_buff *batadv_frag_create(struct sk_buff *skb,
|
|
struct batadv_frag_packet *frag_head,
|
|
unsigned int fragment_size)
|
|
{
|
|
struct sk_buff *skb_fragment;
|
|
unsigned int header_size = sizeof(*frag_head);
|
|
unsigned int mtu = fragment_size + header_size;
|
|
|
|
skb_fragment = netdev_alloc_skb(NULL, mtu + ETH_HLEN);
|
|
if (!skb_fragment)
|
|
goto err;
|
|
|
|
skb_fragment->priority = skb->priority;
|
|
|
|
/* Eat the last mtu-bytes of the skb */
|
|
skb_reserve(skb_fragment, header_size + ETH_HLEN);
|
|
skb_split(skb, skb_fragment, skb->len - fragment_size);
|
|
|
|
/* Add the header */
|
|
skb_push(skb_fragment, header_size);
|
|
memcpy(skb_fragment->data, frag_head, header_size);
|
|
|
|
err:
|
|
return skb_fragment;
|
|
}
|
|
|
|
/**
|
|
* batadv_frag_send_packet() - create up to 16 fragments from the passed skb
|
|
* @skb: skb to create fragments from
|
|
* @orig_node: final destination of the created fragments
|
|
* @neigh_node: next-hop of the created fragments
|
|
*
|
|
* Return: the netdev tx status or a negative errno code on a failure
|
|
*/
|
|
int batadv_frag_send_packet(struct sk_buff *skb,
|
|
struct batadv_orig_node *orig_node,
|
|
struct batadv_neigh_node *neigh_node)
|
|
{
|
|
struct batadv_priv *bat_priv;
|
|
struct batadv_hard_iface *primary_if = NULL;
|
|
struct batadv_frag_packet frag_header;
|
|
struct sk_buff *skb_fragment;
|
|
unsigned int mtu = neigh_node->if_incoming->net_dev->mtu;
|
|
unsigned int header_size = sizeof(frag_header);
|
|
unsigned int max_fragment_size, num_fragments;
|
|
int ret;
|
|
|
|
/* To avoid merge and refragmentation at next-hops we never send
|
|
* fragments larger than BATADV_FRAG_MAX_FRAG_SIZE
|
|
*/
|
|
mtu = min_t(unsigned int, mtu, BATADV_FRAG_MAX_FRAG_SIZE);
|
|
max_fragment_size = mtu - header_size;
|
|
|
|
if (skb->len == 0 || max_fragment_size == 0)
|
|
return -EINVAL;
|
|
|
|
num_fragments = (skb->len - 1) / max_fragment_size + 1;
|
|
max_fragment_size = (skb->len - 1) / num_fragments + 1;
|
|
|
|
/* Don't even try to fragment, if we need more than 16 fragments */
|
|
if (num_fragments > BATADV_FRAG_MAX_FRAGMENTS) {
|
|
ret = -EAGAIN;
|
|
goto free_skb;
|
|
}
|
|
|
|
bat_priv = orig_node->bat_priv;
|
|
primary_if = batadv_primary_if_get_selected(bat_priv);
|
|
if (!primary_if) {
|
|
ret = -EINVAL;
|
|
goto free_skb;
|
|
}
|
|
|
|
/* Create one header to be copied to all fragments */
|
|
frag_header.packet_type = BATADV_UNICAST_FRAG;
|
|
frag_header.version = BATADV_COMPAT_VERSION;
|
|
frag_header.ttl = BATADV_TTL;
|
|
frag_header.seqno = htons(atomic_inc_return(&bat_priv->frag_seqno));
|
|
frag_header.reserved = 0;
|
|
frag_header.no = 0;
|
|
frag_header.total_size = htons(skb->len);
|
|
|
|
/* skb->priority values from 256->263 are magic values to
|
|
* directly indicate a specific 802.1d priority. This is used
|
|
* to allow 802.1d priority to be passed directly in from VLAN
|
|
* tags, etc.
|
|
*/
|
|
if (skb->priority >= 256 && skb->priority <= 263)
|
|
frag_header.priority = skb->priority - 256;
|
|
else
|
|
frag_header.priority = 0;
|
|
|
|
ether_addr_copy(frag_header.orig, primary_if->net_dev->dev_addr);
|
|
ether_addr_copy(frag_header.dest, orig_node->orig);
|
|
|
|
/* Eat and send fragments from the tail of skb */
|
|
while (skb->len > max_fragment_size) {
|
|
/* The initial check in this function should cover this case */
|
|
if (unlikely(frag_header.no == BATADV_FRAG_MAX_FRAGMENTS - 1)) {
|
|
ret = -EINVAL;
|
|
goto put_primary_if;
|
|
}
|
|
|
|
skb_fragment = batadv_frag_create(skb, &frag_header,
|
|
max_fragment_size);
|
|
if (!skb_fragment) {
|
|
ret = -ENOMEM;
|
|
goto put_primary_if;
|
|
}
|
|
|
|
batadv_inc_counter(bat_priv, BATADV_CNT_FRAG_TX);
|
|
batadv_add_counter(bat_priv, BATADV_CNT_FRAG_TX_BYTES,
|
|
skb_fragment->len + ETH_HLEN);
|
|
ret = batadv_send_unicast_skb(skb_fragment, neigh_node);
|
|
if (ret != NET_XMIT_SUCCESS) {
|
|
ret = NET_XMIT_DROP;
|
|
goto put_primary_if;
|
|
}
|
|
|
|
frag_header.no++;
|
|
}
|
|
|
|
/* Make room for the fragment header. */
|
|
if (batadv_skb_head_push(skb, header_size) < 0 ||
|
|
pskb_expand_head(skb, header_size + ETH_HLEN, 0, GFP_ATOMIC) < 0) {
|
|
ret = -ENOMEM;
|
|
goto put_primary_if;
|
|
}
|
|
|
|
memcpy(skb->data, &frag_header, header_size);
|
|
|
|
/* Send the last fragment */
|
|
batadv_inc_counter(bat_priv, BATADV_CNT_FRAG_TX);
|
|
batadv_add_counter(bat_priv, BATADV_CNT_FRAG_TX_BYTES,
|
|
skb->len + ETH_HLEN);
|
|
ret = batadv_send_unicast_skb(skb, neigh_node);
|
|
/* skb was consumed */
|
|
skb = NULL;
|
|
|
|
put_primary_if:
|
|
batadv_hardif_put(primary_if);
|
|
free_skb:
|
|
kfree_skb(skb);
|
|
|
|
return ret;
|
|
}
|