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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-11 08:27:49 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-11 08:27:49 +0000
commitace9429bb58fd418f0c81d4c2835699bddf6bde6 (patch)
treeb2d64bc10158fdd5497876388cd68142ca374ed3 /net/batman-adv/fragmentation.c
parentInitial commit. (diff)
downloadlinux-ace9429bb58fd418f0c81d4c2835699bddf6bde6.tar.xz
linux-ace9429bb58fd418f0c81d4c2835699bddf6bde6.zip
Adding upstream version 6.6.15.upstream/6.6.15
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'net/batman-adv/fragmentation.c')
-rw-r--r--net/batman-adv/fragmentation.c562
1 files changed, 562 insertions, 0 deletions
diff --git a/net/batman-adv/fragmentation.c b/net/batman-adv/fragmentation.c
new file mode 100644
index 0000000000..c120c7c6d2
--- /dev/null
+++ b/net/batman-adv/fragmentation.c
@@ -0,0 +1,562 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (C) 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/lockdep.h>
+#include <linux/minmax.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"
+
+/**
+ * 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:
+ batadv_orig_node_put(orig_node_dst);
+ 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;
+ }
+
+ /* GRO might have added fragments to the fragment list instead of
+ * frags[]. But this is not handled by skb_split and must be
+ * linearized to avoid incorrect length information after all
+ * batman-adv fragments were created and submitted to the
+ * hard-interface
+ */
+ if (skb_has_frag_list(skb) && __skb_linearize(skb)) {
+ ret = -ENOMEM;
+ 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;
+}