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