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|
// SPDX-License-Identifier: GPL-2.0-or-later
/* 6LoWPAN fragment reassembly
*
* Authors:
* Alexander Aring <aar@pengutronix.de>
*
* Based on: net/ipv6/reassembly.c
*/
#define pr_fmt(fmt) "6LoWPAN: " fmt
#include <linux/net.h>
#include <linux/list.h>
#include <linux/netdevice.h>
#include <linux/random.h>
#include <linux/jhash.h>
#include <linux/skbuff.h>
#include <linux/slab.h>
#include <linux/export.h>
#include <net/ieee802154_netdev.h>
#include <net/6lowpan.h>
#include <net/ipv6_frag.h>
#include <net/inet_frag.h>
#include <net/ip.h>
#include "6lowpan_i.h"
static const char lowpan_frags_cache_name[] = "lowpan-frags";
static struct inet_frags lowpan_frags;
static int lowpan_frag_reasm(struct lowpan_frag_queue *fq, struct sk_buff *skb,
struct sk_buff *prev, struct net_device *ldev);
static void lowpan_frag_init(struct inet_frag_queue *q, const void *a)
{
const struct frag_lowpan_compare_key *key = a;
BUILD_BUG_ON(sizeof(*key) > sizeof(q->key));
memcpy(&q->key, key, sizeof(*key));
}
static void lowpan_frag_expire(struct timer_list *t)
{
struct inet_frag_queue *frag = from_timer(frag, t, timer);
struct frag_queue *fq;
fq = container_of(frag, struct frag_queue, q);
spin_lock(&fq->q.lock);
if (fq->q.flags & INET_FRAG_COMPLETE)
goto out;
inet_frag_kill(&fq->q);
out:
spin_unlock(&fq->q.lock);
inet_frag_put(&fq->q);
}
static inline struct lowpan_frag_queue *
fq_find(struct net *net, const struct lowpan_802154_cb *cb,
const struct ieee802154_addr *src,
const struct ieee802154_addr *dst)
{
struct netns_ieee802154_lowpan *ieee802154_lowpan =
net_ieee802154_lowpan(net);
struct frag_lowpan_compare_key key = {};
struct inet_frag_queue *q;
key.tag = cb->d_tag;
key.d_size = cb->d_size;
key.src = *src;
key.dst = *dst;
q = inet_frag_find(ieee802154_lowpan->fqdir, &key);
if (!q)
return NULL;
return container_of(q, struct lowpan_frag_queue, q);
}
static int lowpan_frag_queue(struct lowpan_frag_queue *fq,
struct sk_buff *skb, u8 frag_type)
{
struct sk_buff *prev_tail;
struct net_device *ldev;
int end, offset, err;
/* inet_frag_queue_* functions use skb->cb; see struct ipfrag_skb_cb
* in inet_fragment.c
*/
BUILD_BUG_ON(sizeof(struct lowpan_802154_cb) > sizeof(struct inet_skb_parm));
BUILD_BUG_ON(sizeof(struct lowpan_802154_cb) > sizeof(struct inet6_skb_parm));
if (fq->q.flags & INET_FRAG_COMPLETE)
goto err;
offset = lowpan_802154_cb(skb)->d_offset << 3;
end = lowpan_802154_cb(skb)->d_size;
/* Is this the final fragment? */
if (offset + skb->len == end) {
/* If we already have some bits beyond end
* or have different end, the segment is corrupted.
*/
if (end < fq->q.len ||
((fq->q.flags & INET_FRAG_LAST_IN) && end != fq->q.len))
goto err;
fq->q.flags |= INET_FRAG_LAST_IN;
fq->q.len = end;
} else {
if (end > fq->q.len) {
/* Some bits beyond end -> corruption. */
if (fq->q.flags & INET_FRAG_LAST_IN)
goto err;
fq->q.len = end;
}
}
ldev = skb->dev;
if (ldev)
skb->dev = NULL;
barrier();
prev_tail = fq->q.fragments_tail;
err = inet_frag_queue_insert(&fq->q, skb, offset, end);
if (err)
goto err;
fq->q.stamp = skb->tstamp;
if (frag_type == LOWPAN_DISPATCH_FRAG1)
fq->q.flags |= INET_FRAG_FIRST_IN;
fq->q.meat += skb->len;
add_frag_mem_limit(fq->q.fqdir, skb->truesize);
if (fq->q.flags == (INET_FRAG_FIRST_IN | INET_FRAG_LAST_IN) &&
fq->q.meat == fq->q.len) {
int res;
unsigned long orefdst = skb->_skb_refdst;
skb->_skb_refdst = 0UL;
res = lowpan_frag_reasm(fq, skb, prev_tail, ldev);
skb->_skb_refdst = orefdst;
return res;
}
skb_dst_drop(skb);
return -1;
err:
kfree_skb(skb);
return -1;
}
/* Check if this packet is complete.
*
* It is called with locked fq, and caller must check that
* queue is eligible for reassembly i.e. it is not COMPLETE,
* the last and the first frames arrived and all the bits are here.
*/
static int lowpan_frag_reasm(struct lowpan_frag_queue *fq, struct sk_buff *skb,
struct sk_buff *prev_tail, struct net_device *ldev)
{
void *reasm_data;
inet_frag_kill(&fq->q);
reasm_data = inet_frag_reasm_prepare(&fq->q, skb, prev_tail);
if (!reasm_data)
goto out_oom;
inet_frag_reasm_finish(&fq->q, skb, reasm_data, false);
skb->dev = ldev;
skb->tstamp = fq->q.stamp;
fq->q.rb_fragments = RB_ROOT;
fq->q.fragments_tail = NULL;
fq->q.last_run_head = NULL;
return 1;
out_oom:
net_dbg_ratelimited("lowpan_frag_reasm: no memory for reassembly\n");
return -1;
}
static int lowpan_frag_rx_handlers_result(struct sk_buff *skb,
lowpan_rx_result res)
{
switch (res) {
case RX_QUEUED:
return NET_RX_SUCCESS;
case RX_CONTINUE:
/* nobody cared about this packet */
net_warn_ratelimited("%s: received unknown dispatch\n",
__func__);
/* fall-through */
default:
/* all others failure */
return NET_RX_DROP;
}
}
static lowpan_rx_result lowpan_frag_rx_h_iphc(struct sk_buff *skb)
{
int ret;
if (!lowpan_is_iphc(*skb_network_header(skb)))
return RX_CONTINUE;
ret = lowpan_iphc_decompress(skb);
if (ret < 0)
return RX_DROP;
return RX_QUEUED;
}
static int lowpan_invoke_frag_rx_handlers(struct sk_buff *skb)
{
lowpan_rx_result res;
#define CALL_RXH(rxh) \
do { \
res = rxh(skb); \
if (res != RX_CONTINUE) \
goto rxh_next; \
} while (0)
/* likely at first */
CALL_RXH(lowpan_frag_rx_h_iphc);
CALL_RXH(lowpan_rx_h_ipv6);
rxh_next:
return lowpan_frag_rx_handlers_result(skb, res);
#undef CALL_RXH
}
#define LOWPAN_FRAG_DGRAM_SIZE_HIGH_MASK 0x07
#define LOWPAN_FRAG_DGRAM_SIZE_HIGH_SHIFT 8
static int lowpan_get_cb(struct sk_buff *skb, u8
|