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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 struct rb_root rb_root = RB_ROOT;
static struct lowpan_nhc *lowpan_nexthdr_nhcs[NEXTHDR_MAX + 1];
static DEFINE_SPINLOCK(lowpan_nhc_lock);
static int lowpan_nhc_insert(struct lowpan_nhc *nhc)
{
struct rb_node **new = &rb_root.rb_node, *parent = NULL;
/* Figure out where to put new node */
while (*new) {
struct lowpan_nhc *this = rb_entry(*new, struct lowpan_nhc,
node);
int result, len_dif, len;
len_dif = nhc->idlen - this->idlen;
if (nhc->idlen < this->idlen)
len = nhc->idlen;
else
len = this->idlen;
result = memcmp(nhc->id, this->id, len);
if (!result)
result = len_dif;
parent = *new;
if (result < 0)
new = &((*new)->rb_left);
else if (result > 0)
new = &((*new)->rb_right);
else
return -EEXIST;
}
/* Add new node and rebalance tree. */
rb_link_node(&nhc->node, parent, new);
rb_insert_color(&nhc->node, &rb_root);
return 0;
}
static void lowpan_nhc_remove(struct lowpan_nhc *nhc)
{
rb_erase(&nhc->node, &rb_root);
}
static struct lowpan_nhc *lowpan_nhc_by_nhcid(const struct sk_buff *skb)
{
struct rb_node *node = rb_root.rb_node;
const u8 *nhcid_skb_ptr = skb->data;
while (node) {
struct lowpan_nhc *nhc = rb_entry(node, struct lowpan_nhc,
node);
u8 nhcid_skb_ptr_masked[LOWPAN_NHC_MAX_ID_LEN];
int result, i;
if (nhcid_skb_ptr + nhc->idlen > skb->data + skb->len)
return NULL;
/* copy and mask afterwards the nhid value from skb */
memcpy(nhcid_skb_ptr_masked, nhcid_skb_ptr, nhc->idlen);
for (i = 0; i < nhc->idlen; i++)
nhcid_skb_ptr_masked[i] &= nhc->idmask[i];
result = memcmp(nhcid_skb_ptr_masked, nhc->id, nhc->idlen);
if (result < 0)
node = node->rb_left;
else if (result > 0)
node = node->rb_right;
else
return nhc;
}
return NULL;
}
int lowpan_nhc_check_compression(struct sk_buff *skb,
const struct ipv6hdr *hdr, u8 **hc_ptr)
{
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;
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)
{
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(struct lowpan_nhc *nhc)
{
int ret;
if (!nhc->idlen || !nhc->idsetup)
return -EINVAL;
WARN_ONCE(nhc->idlen > LOWPAN_NHC_MAX_ID_LEN,
"LOWPAN_NHC_MAX_ID_LEN should be updated to %zd.\n",
nhc->idlen);
nhc->idsetup(nhc);
spin_lock_bh(&lowpan_nhc_lock);
if (lowpan_nexthdr_nhcs[nhc->nexthdr]) {
ret = -EEXIST;
goto out;
}
ret = lowpan_nhc_insert(nhc);
if (ret < 0)
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(struct lowpan_nhc *nhc)
{
spin_lock_bh(&lowpan_nhc_lock);
lowpan_nhc_remove(nhc);
lowpan_nexthdr_nhcs[nhc->nexthdr] = NULL;
spin_unlock_bh(&lowpan_nhc_lock);
synchronize_net();
}
EXPORT_SYMBOL(lowpan_nhc_del);
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