Orange Pi5 kernel

// SPDX-License-Identifier: GPL-2.0
/* Copyright (C) 2013-2020  B.A.T.M.A.N. contributors:
 *
 * Martin Hundebøll <martin@hundeboll.net>
 */
 
#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 the 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 the packet is merged or buffered, false when skb is 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
 * @net_dev: outgoing device for fragment
 * @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 net_device *net_dev,
<------><------><------><------><------>  struct sk_buff *skb,
<------><------><------><------><------>  struct batadv_frag_packet *frag_head,
<------><------><------><------><------>  unsigned int fragment_size)
{
<------>unsigned int ll_reserved = LL_RESERVED_SPACE(net_dev);
<------>unsigned int tailroom = net_dev->needed_tailroom;
<------>struct sk_buff *skb_fragment;
<------>unsigned int header_size = sizeof(*frag_head);
<------>unsigned int mtu = fragment_size + header_size;
 
<------>skb_fragment = dev_alloc_skb(ll_reserved + mtu + tailroom);
<------>if (!skb_fragment)
<------><------>goto err;
 
<------>skb_fragment->priority = skb->priority;
 
<------>/* Eat the last mtu-bytes of the skb */
<------>skb_reserve(skb_fragment, ll_reserved + header_size);
<------>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 net_device *net_dev = neigh_node->if_incoming->net_dev;
<------>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 = 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(net_dev, 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 sure that there is at least enough head for the fragmentation
<------> * and ethernet headers
<------> */
<------>ret = skb_cow_head(skb, ETH_HLEN + header_size);
<------>if (ret < 0)
<------><------>goto put_primary_if;
 
<------>skb_push(skb, header_size);
<------>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;
}