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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* 6LoWPAN next header compression
*
* Authors:
* Alexander Aring <aar@pengutronix.de>
*/
#include <linux/netdevice.h>
#include <net/ipv6.h>
#include "nhc.h"
static const struct lowpan_nhc *lowpan_nexthdr_nhcs[NEXTHDR_MAX + 1];
static DEFINE_SPINLOCK(lowpan_nhc_lock);
static const struct lowpan_nhc *lowpan_nhc_by_nhcid(struct sk_buff *skb)
{
const struct lowpan_nhc *nhc;
int i;
u8 id;
if (!pskb_may_pull(skb, 1))
return NULL;
id = *skb->data;
for (i = 0; i < NEXTHDR_MAX + 1; i++) {
nhc = lowpan_nexthdr_nhcs[i];
if (!nhc)
continue;
if ((id & nhc->idmask) == nhc->id)
return nhc;
}
return NULL;
}
int lowpan_nhc_check_compression(struct sk_buff *skb,
const struct ipv6hdr *hdr, u8 **hc_ptr)
{
const struct lowpan_nhc *nhc;
int ret = 0;
spin_lock_bh(&lowpan_nhc_lock);
nhc = lowpan_nexthdr_nhcs[hdr->nexthdr];
if (!(nhc && nhc->compress))
ret = -ENOENT;
spin_unlock_bh(&lowpan_nhc_lock);
return ret;
}
int lowpan_nhc_do_compression(struct sk_buff *skb, const struct ipv6hdr *hdr,
u8 **hc_ptr)
{
int ret;
const struct lowpan_nhc *nhc;
spin_lock_bh(&lowpan_nhc_lock);
nhc = lowpan_nexthdr_nhcs[hdr->nexthdr];
/* check if the nhc module was removed in unlocked part.
* TODO: this is a workaround we should prevent unloading
* of nhc modules while unlocked part, this will always drop
* the lowpan packet but it's very unlikely.
*
* Solution isn't easy because we need to decide at
* lowpan_nhc_check_compression if we do a compression or not.
* Because the inline data which is added to skb, we can't move this
* handling.
*/
if (unlikely(!nhc || !nhc->compress)) {
ret = -EINVAL;
goto out;
}
/* In the case of RAW sockets the transport header is not set by
* the ip6 stack so we must set it ourselves
*/
if (skb->transport_header == skb->network_header)
skb_set_transport_header(skb, sizeof(struct ipv6hdr));
ret = nhc->compress(skb, hc_ptr);
if (ret < 0)
goto out;
/* skip the transport header */
skb_pull(skb, nhc->nexthdrlen);
out:
spin_unlock_bh(&lowpan_nhc_lock);
return ret;
}
int lowpan_nhc_do_uncompression(struct sk_buff *skb,
const struct net_device *dev,
struct ipv6hdr *hdr)
{
const struct lowpan_nhc *nhc;
int ret;
spin_lock_bh(&lowpan_nhc_lock);
nhc = lowpan_nhc_by_nhcid(skb);
if (nhc) {
if (nhc->uncompress) {
ret = nhc->uncompress(skb, sizeof(struct ipv6hdr) +
nhc->nexthdrlen);
if (ret < 0) {
spin_unlock_bh(&lowpan_nhc_lock);
return ret;
}
} else {
spin_unlock_bh(&lowpan_nhc_lock);
netdev_warn(dev, "received nhc id for %s which is not implemented.\n",
nhc->name);
return -ENOTSUPP;
}
} else {
spin_unlock_bh(&lowpan_nhc_lock);
netdev_warn(dev, "received unknown nhc id which was not found.\n");
return -ENOENT;
}
hdr->nexthdr = nhc->nexthdr;
skb_reset_transport_header(skb);
raw_dump_table(__func__, "raw transport header dump",
skb_transport_header(skb), nhc->nexthdrlen);
spin_unlock_bh(&lowpan_nhc_lock);
return 0;
}
int lowpan_nhc_add(const struct lowpan_nhc *nhc)
{
int ret = 0;
spin_lock_bh(&lowpan_nhc_lock);
if (lowpan_nexthdr_nhcs[nhc->nexthdr]) {
ret = -EEXIST;
goto out;
}
lowpan_nexthdr_nhcs[nhc->nexthdr] = nhc;
out:
spin_unlock_bh(&lowpan_nhc_lock);
return ret;
}
EXPORT_SYMBOL(lowpan_nhc_add);
void lowpan_nhc_del(const struct lowpan_nhc *nhc)
{
spin_lock_bh(&lowpan_nhc_lock);
lowpan_nexthdr_nhcs[nhc->nexthdr] = NULL;
spin_unlock_bh(&lowpan_nhc_lock);
synchronize_net();
}
EXPORT_SYMBOL(lowpan_nhc_del);
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