cregit-Linux how code gets into the kernel

Release 4.8 net/batman-adv/fragmentation.c

Directory: net/batman-adv
/* Copyright (C) 2013-2016  B.A.T.M.A.N. contributors:
 * Martin Hundebøll <>
 * 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
 * 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 <>.

#include "fragmentation.h"
#include "main.h"

#include <linux/atomic.h>
#include <linux/byteorder/generic.h>
#include <linux/etherdevice.h>
#include <linux/fs.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 "hard-interface.h"
#include "originator.h"
#include "packet.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.
 * Free fragments in the passed hlist. Should be called with appropriate lock.

static void batadv_frag_clear_chain(struct hlist_head *head) { struct batadv_frag_list_entry *entry; struct hlist_node *node; hlist_for_each_entry_safe(entry, node, head, list) { hlist_del(&entry->list); kfree_skb(entry->skb); kfree(entry); } }


martin hundebollmartin hundeboll53100.00%1100.00%

/** * 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->head); chain->size = 0; } spin_unlock_bh(&chain->lock); } }


martin hundebollmartin hundeboll9194.79%133.33%
sven eckelmannsven eckelmann55.21%266.67%

/** * 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; }


martin hundebollmartin hundeboll28100.00%1100.00%

/** * 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->head)) batadv_frag_clear_chain(&chain->head); chain->size = 0; chain->seqno = seqno; return true; }


martin hundebollmartin hundeboll5886.57%133.33%
sven eckelmannsven eckelmann913.43%266.67%

/** * 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->head); 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->head, 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->head); chain->size = 0; } else if (ntohs(frag_packet->total_size) == chain->size) { /* All fragments received. Hand over chain to caller. */ hlist_move_list(&chain->head, chain_out); chain->size = 0; } err_unlock: spin_unlock_bh(&chain->lock); err: if (!ret) kfree(frag_entry_new); return ret; }


martin hundebollmartin hundeboll40591.22%116.67%
sven eckelmannsven eckelmann388.56%466.67%
ken heliasken helias10.23%116.67%

/** * 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 = NULL; int size, hdr_size = sizeof(struct batadv_frag_packet); /* 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); /* 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; goto free; } /* Move the existing MAC header to just before the payload. (Override * the fragment header.) */ skb_pull_rcsum(skb_out, hdr_size); 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; memcpy(skb_put(skb_out, size), entry->skb->data + hdr_size, size); } free: /* Locking is not needed, because 'chain' is not part of any orig. */ batadv_frag_clear_chain(chain); return skb_out; }


martin hundebollmartin hundeboll20290.58%133.33%
sven eckelmannsven eckelmann219.42%266.67%

/** * 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 leave skb as is. * * 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: *skb = skb_out; ret = true; out_err: return ret; }


martin hundebollmartin hundeboll96100.00%1100.00%

/** * 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 = NULL; 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; }


martin hundebollmartin hundeboll18797.91%120.00%
sven eckelmannsven eckelmann31.57%360.00%
antonio quartulliantonio quartulli10.52%120.00%

/** * batadv_frag_create - create a fragment from skb * @skb: skb to create fragment from * @frag_head: header to use in new fragment * @mtu: 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 mtu) { struct sk_buff *skb_fragment; unsigned int header_size = sizeof(*frag_head); unsigned int fragment_size = mtu - 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; }


martin hundebollmartin hundeboll11394.96%133.33%
andrew lunnandrew lunn43.36%133.33%
sven eckelmannsven eckelmann21.68%133.33%

/** * 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 -1 in case of error. * When -1 is returned the skb is not consumed. */
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, max_packet_size; int ret = -1; /* 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; max_packet_size = max_fragment_size * BATADV_FRAG_MAX_FRAGMENTS; /* Don't even try to fragment, if we need more than 16 fragments */ if (skb->len > max_packet_size) goto out; bat_priv = orig_node->bat_priv; primary_if = batadv_primary_if_get_selected(bat_priv); if (!primary_if) goto out; /* 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; = 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; 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) { skb_fragment = batadv_frag_create(skb, &frag_header, mtu); if (!skb_fragment) goto out; 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) { /* return -1 so that the caller can free the original * skb */ ret = -1; goto out; }; /* The initial check in this function should cover this case */ if ( == BATADV_FRAG_MAX_FRAGMENTS - 1) { ret = -1; goto out; } } /* 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) goto out; 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); out: if (primary_if) batadv_hardif_put(primary_if); return ret; }


martin hundebollmartin hundeboll33879.34%112.50%
antonio quartulliantonio quartulli5613.15%450.00%
andrew lunnandrew lunn255.87%112.50%
sven eckelmannsven eckelmann71.64%225.00%

Overall Contributors

martin hundebollmartin hundeboll159187.56%28.33%
sven eckelmannsven eckelmann1387.59%1562.50%
antonio quartulliantonio quartulli583.19%416.67%
andrew lunnandrew lunn291.60%28.33%
ken heliasken helias10.06%14.17%
Directory: net/batman-adv
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