linux/net/batman-adv/unicast.c
Linus Lüssing 43c70ad5ce batman-adv: Increase orig_node refcount before releasing rcu read lock
When unicast_send_skb() is increasing the orig_node's refcount another
thread might have been freeing this orig_node already. We need to
increase the refcount in the rcu read lock protected area to avoid that.

Signed-off-by: Linus Lüssing <linus.luessing@ascom.ch>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
2011-03-05 12:50:12 +01:00

357 lines
9 KiB
C

/*
* Copyright (C) 2010-2011 B.A.T.M.A.N. contributors:
*
* Andreas Langer
*
* 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, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA
*
*/
#include "main.h"
#include "unicast.h"
#include "send.h"
#include "soft-interface.h"
#include "gateway_client.h"
#include "originator.h"
#include "hash.h"
#include "translation-table.h"
#include "routing.h"
#include "hard-interface.h"
static struct sk_buff *frag_merge_packet(struct list_head *head,
struct frag_packet_list_entry *tfp,
struct sk_buff *skb)
{
struct unicast_frag_packet *up =
(struct unicast_frag_packet *)skb->data;
struct sk_buff *tmp_skb;
struct unicast_packet *unicast_packet;
int hdr_len = sizeof(struct unicast_packet);
int uni_diff = sizeof(struct unicast_frag_packet) - hdr_len;
/* set skb to the first part and tmp_skb to the second part */
if (up->flags & UNI_FRAG_HEAD) {
tmp_skb = tfp->skb;
} else {
tmp_skb = skb;
skb = tfp->skb;
}
skb_pull(tmp_skb, sizeof(struct unicast_frag_packet));
if (pskb_expand_head(skb, 0, tmp_skb->len, GFP_ATOMIC) < 0) {
/* free buffered skb, skb will be freed later */
kfree_skb(tfp->skb);
return NULL;
}
/* move free entry to end */
tfp->skb = NULL;
tfp->seqno = 0;
list_move_tail(&tfp->list, head);
memcpy(skb_put(skb, tmp_skb->len), tmp_skb->data, tmp_skb->len);
kfree_skb(tmp_skb);
memmove(skb->data + uni_diff, skb->data, hdr_len);
unicast_packet = (struct unicast_packet *) skb_pull(skb, uni_diff);
unicast_packet->packet_type = BAT_UNICAST;
return skb;
}
static void frag_create_entry(struct list_head *head, struct sk_buff *skb)
{
struct frag_packet_list_entry *tfp;
struct unicast_frag_packet *up =
(struct unicast_frag_packet *)skb->data;
/* free and oldest packets stand at the end */
tfp = list_entry((head)->prev, typeof(*tfp), list);
kfree_skb(tfp->skb);
tfp->seqno = ntohs(up->seqno);
tfp->skb = skb;
list_move(&tfp->list, head);
return;
}
static int frag_create_buffer(struct list_head *head)
{
int i;
struct frag_packet_list_entry *tfp;
for (i = 0; i < FRAG_BUFFER_SIZE; i++) {
tfp = kmalloc(sizeof(struct frag_packet_list_entry),
GFP_ATOMIC);
if (!tfp) {
frag_list_free(head);
return -ENOMEM;
}
tfp->skb = NULL;
tfp->seqno = 0;
INIT_LIST_HEAD(&tfp->list);
list_add(&tfp->list, head);
}
return 0;
}
static struct frag_packet_list_entry *frag_search_packet(struct list_head *head,
struct unicast_frag_packet *up)
{
struct frag_packet_list_entry *tfp;
struct unicast_frag_packet *tmp_up = NULL;
uint16_t search_seqno;
if (up->flags & UNI_FRAG_HEAD)
search_seqno = ntohs(up->seqno)+1;
else
search_seqno = ntohs(up->seqno)-1;
list_for_each_entry(tfp, head, list) {
if (!tfp->skb)
continue;
if (tfp->seqno == ntohs(up->seqno))
goto mov_tail;
tmp_up = (struct unicast_frag_packet *)tfp->skb->data;
if (tfp->seqno == search_seqno) {
if ((tmp_up->flags & UNI_FRAG_HEAD) !=
(up->flags & UNI_FRAG_HEAD))
return tfp;
else
goto mov_tail;
}
}
return NULL;
mov_tail:
list_move_tail(&tfp->list, head);
return NULL;
}
void frag_list_free(struct list_head *head)
{
struct frag_packet_list_entry *pf, *tmp_pf;
if (!list_empty(head)) {
list_for_each_entry_safe(pf, tmp_pf, head, list) {
kfree_skb(pf->skb);
list_del(&pf->list);
kfree(pf);
}
}
return;
}
/* frag_reassemble_skb():
* returns NET_RX_DROP if the operation failed - skb is left intact
* returns NET_RX_SUCCESS if the fragment was buffered (skb_new will be NULL)
* or the skb could be reassembled (skb_new will point to the new packet and
* skb was freed)
*/
int frag_reassemble_skb(struct sk_buff *skb, struct bat_priv *bat_priv,
struct sk_buff **new_skb)
{
struct orig_node *orig_node;
struct frag_packet_list_entry *tmp_frag_entry;
int ret = NET_RX_DROP;
struct unicast_frag_packet *unicast_packet =
(struct unicast_frag_packet *)skb->data;
*new_skb = NULL;
spin_lock_bh(&bat_priv->orig_hash_lock);
rcu_read_lock();
orig_node = ((struct orig_node *)
hash_find(bat_priv->orig_hash, compare_orig, choose_orig,
unicast_packet->orig));
rcu_read_unlock();
if (!orig_node) {
pr_debug("couldn't find originator in orig_hash\n");
goto out;
}
orig_node->last_frag_packet = jiffies;
if (list_empty(&orig_node->frag_list) &&
frag_create_buffer(&orig_node->frag_list)) {
pr_debug("couldn't create frag buffer\n");
goto out;
}
tmp_frag_entry = frag_search_packet(&orig_node->frag_list,
unicast_packet);
if (!tmp_frag_entry) {
frag_create_entry(&orig_node->frag_list, skb);
ret = NET_RX_SUCCESS;
goto out;
}
*new_skb = frag_merge_packet(&orig_node->frag_list, tmp_frag_entry,
skb);
/* if not, merge failed */
if (*new_skb)
ret = NET_RX_SUCCESS;
out:
spin_unlock_bh(&bat_priv->orig_hash_lock);
return ret;
}
int frag_send_skb(struct sk_buff *skb, struct bat_priv *bat_priv,
struct batman_if *batman_if, uint8_t dstaddr[])
{
struct unicast_packet tmp_uc, *unicast_packet;
struct sk_buff *frag_skb;
struct unicast_frag_packet *frag1, *frag2;
int uc_hdr_len = sizeof(struct unicast_packet);
int ucf_hdr_len = sizeof(struct unicast_frag_packet);
int data_len = skb->len - uc_hdr_len;
int large_tail = 0;
uint16_t seqno;
if (!bat_priv->primary_if)
goto dropped;
frag_skb = dev_alloc_skb(data_len - (data_len / 2) + ucf_hdr_len);
if (!frag_skb)
goto dropped;
skb_reserve(frag_skb, ucf_hdr_len);
unicast_packet = (struct unicast_packet *) skb->data;
memcpy(&tmp_uc, unicast_packet, uc_hdr_len);
skb_split(skb, frag_skb, data_len / 2 + uc_hdr_len);
if (my_skb_head_push(skb, ucf_hdr_len - uc_hdr_len) < 0 ||
my_skb_head_push(frag_skb, ucf_hdr_len) < 0)
goto drop_frag;
frag1 = (struct unicast_frag_packet *)skb->data;
frag2 = (struct unicast_frag_packet *)frag_skb->data;
memcpy(frag1, &tmp_uc, sizeof(struct unicast_packet));
frag1->ttl--;
frag1->version = COMPAT_VERSION;
frag1->packet_type = BAT_UNICAST_FRAG;
memcpy(frag1->orig, bat_priv->primary_if->net_dev->dev_addr, ETH_ALEN);
memcpy(frag2, frag1, sizeof(struct unicast_frag_packet));
if (data_len & 1)
large_tail = UNI_FRAG_LARGETAIL;
frag1->flags = UNI_FRAG_HEAD | large_tail;
frag2->flags = large_tail;
seqno = atomic_add_return(2, &batman_if->frag_seqno);
frag1->seqno = htons(seqno - 1);
frag2->seqno = htons(seqno);
send_skb_packet(skb, batman_if, dstaddr);
send_skb_packet(frag_skb, batman_if, dstaddr);
return NET_RX_SUCCESS;
drop_frag:
kfree_skb(frag_skb);
dropped:
kfree_skb(skb);
return NET_RX_DROP;
}
int unicast_send_skb(struct sk_buff *skb, struct bat_priv *bat_priv)
{
struct ethhdr *ethhdr = (struct ethhdr *)skb->data;
struct unicast_packet *unicast_packet;
struct orig_node *orig_node = NULL;
struct batman_if *batman_if;
struct neigh_node *neigh_node;
int data_len = skb->len;
uint8_t dstaddr[6];
int ret = 1;
spin_lock_bh(&bat_priv->orig_hash_lock);
/* get routing information */
if (is_multicast_ether_addr(ethhdr->h_dest)) {
orig_node = (struct orig_node *)gw_get_selected(bat_priv);
if (orig_node)
goto find_router;
}
/* check for hna host - increases orig_node refcount */
orig_node = transtable_search(bat_priv, ethhdr->h_dest);
find_router:
/* find_router() increases neigh_nodes refcount if found. */
neigh_node = find_router(bat_priv, orig_node, NULL);
if (!neigh_node)
goto unlock;
if (neigh_node->if_incoming->if_status != IF_ACTIVE)
goto unlock;
if (my_skb_head_push(skb, sizeof(struct unicast_packet)) < 0)
goto unlock;
/* don't lock while sending the packets ... we therefore
* copy the required data before sending */
batman_if = neigh_node->if_incoming;
memcpy(dstaddr, neigh_node->addr, ETH_ALEN);
spin_unlock_bh(&bat_priv->orig_hash_lock);
unicast_packet = (struct unicast_packet *)skb->data;
unicast_packet->version = COMPAT_VERSION;
/* batman packet type: unicast */
unicast_packet->packet_type = BAT_UNICAST;
/* set unicast ttl */
unicast_packet->ttl = TTL;
/* copy the destination for faster routing */
memcpy(unicast_packet->dest, orig_node->orig, ETH_ALEN);
if (atomic_read(&bat_priv->fragmentation) &&
data_len + sizeof(struct unicast_packet) >
batman_if->net_dev->mtu) {
/* send frag skb decreases ttl */
unicast_packet->ttl++;
ret = frag_send_skb(skb, bat_priv, batman_if, dstaddr);
goto out;
}
send_skb_packet(skb, batman_if, dstaddr);
ret = 0;
goto out;
unlock:
spin_unlock_bh(&bat_priv->orig_hash_lock);
out:
if (neigh_node)
neigh_node_free_ref(neigh_node);
if (orig_node)
kref_put(&orig_node->refcount, orig_node_free_ref);
if (ret == 1)
kfree_skb(skb);
return ret;
}