--- /dev/null
+/* 6LoWPAN fragment reassembly
+ *
+ *
+ * Authors:
+ * Alexander Aring <aar@pengutronix.de>
+ *
+ * Based on: net/ipv6/reassembly.c
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#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.h>
+#include <net/inet_frag.h>
+
+#include "6lowpan_i.h"
+
+static const char lowpan_frags_cache_name[] = "lowpan-frags";
+
+struct lowpan_frag_info {
+ u16 d_tag;
+ u16 d_size;
+ u8 d_offset;
+};
+
+static struct lowpan_frag_info *lowpan_cb(struct sk_buff *skb)
+{
+ return (struct lowpan_frag_info *)skb->cb;
+}
+
+static struct inet_frags lowpan_frags;
+
+static int lowpan_frag_reasm(struct lowpan_frag_queue *fq,
+ struct sk_buff *prev, struct net_device *dev);
+
+static unsigned int lowpan_hash_frag(u16 tag, u16 d_size,
+ const struct ieee802154_addr *saddr,
+ const struct ieee802154_addr *daddr)
+{
+ net_get_random_once(&lowpan_frags.rnd, sizeof(lowpan_frags.rnd));
+ return jhash_3words(ieee802154_addr_hash(saddr),
+ ieee802154_addr_hash(daddr),
+ (__force u32)(tag + (d_size << 16)),
+ lowpan_frags.rnd);
+}
+
+static unsigned int lowpan_hashfn(const struct inet_frag_queue *q)
+{
+ const struct lowpan_frag_queue *fq;
+
+ fq = container_of(q, struct lowpan_frag_queue, q);
+ return lowpan_hash_frag(fq->tag, fq->d_size, &fq->saddr, &fq->daddr);
+}
+
+static bool lowpan_frag_match(const struct inet_frag_queue *q, const void *a)
+{
+ const struct lowpan_frag_queue *fq;
+ const struct lowpan_create_arg *arg = a;
+
+ fq = container_of(q, struct lowpan_frag_queue, q);
+ return fq->tag == arg->tag && fq->d_size == arg->d_size &&
+ ieee802154_addr_equal(&fq->saddr, arg->src) &&
+ ieee802154_addr_equal(&fq->daddr, arg->dst);
+}
+
+static void lowpan_frag_init(struct inet_frag_queue *q, const void *a)
+{
+ const struct lowpan_create_arg *arg = a;
+ struct lowpan_frag_queue *fq;
+
+ fq = container_of(q, struct lowpan_frag_queue, q);
+
+ fq->tag = arg->tag;
+ fq->d_size = arg->d_size;
+ fq->saddr = *arg->src;
+ fq->daddr = *arg->dst;
+}
+
+static void lowpan_frag_expire(unsigned long data)
+{
+ struct frag_queue *fq;
+ struct net *net;
+
+ fq = container_of((struct inet_frag_queue *)data, struct frag_queue, q);
+ net = container_of(fq->q.net, struct net, ieee802154_lowpan.frags);
+
+ spin_lock(&fq->q.lock);
+
+ if (fq->q.flags & INET_FRAG_COMPLETE)
+ goto out;
+
+ inet_frag_kill(&fq->q, &lowpan_frags);
+out:
+ spin_unlock(&fq->q.lock);
+ inet_frag_put(&fq->q, &lowpan_frags);
+}
+
+static inline struct lowpan_frag_queue *
+fq_find(struct net *net, const struct lowpan_frag_info *frag_info,
+ const struct ieee802154_addr *src,
+ const struct ieee802154_addr *dst)
+{
+ struct inet_frag_queue *q;
+ struct lowpan_create_arg arg;
+ unsigned int hash;
+ struct netns_ieee802154_lowpan *ieee802154_lowpan =
+ net_ieee802154_lowpan(net);
+
+ arg.tag = frag_info->d_tag;
+ arg.d_size = frag_info->d_size;
+ arg.src = src;
+ arg.dst = dst;
+
+ hash = lowpan_hash_frag(frag_info->d_tag, frag_info->d_size, src, dst);
+
+ q = inet_frag_find(&ieee802154_lowpan->frags,
+ &lowpan_frags, &arg, hash);
+ if (IS_ERR_OR_NULL(q)) {
+ inet_frag_maybe_warn_overflow(q, pr_fmt());
+ 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, const u8 frag_type)
+{
+ struct sk_buff *prev, *next;
+ struct net_device *dev;
+ int end, offset;
+
+ if (fq->q.flags & INET_FRAG_COMPLETE)
+ goto err;
+
+ offset = lowpan_cb(skb)->d_offset << 3;
+ end = lowpan_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;
+ }
+ }
+
+ /* Find out which fragments are in front and at the back of us
+ * in the chain of fragments so far. We must know where to put
+ * this fragment, right?
+ */
+ prev = fq->q.fragments_tail;
+ if (!prev || lowpan_cb(prev)->d_offset < lowpan_cb(skb)->d_offset) {
+ next = NULL;
+ goto found;
+ }
+ prev = NULL;
+ for (next = fq->q.fragments; next != NULL; next = next->next) {
+ if (lowpan_cb(next)->d_offset >= lowpan_cb(skb)->d_offset)
+ break; /* bingo! */
+ prev = next;
+ }
+
+found:
+ /* Insert this fragment in the chain of fragments. */
+ skb->next = next;
+ if (!next)
+ fq->q.fragments_tail = skb;
+ if (prev)
+ prev->next = skb;
+ else
+ fq->q.fragments = skb;
+
+ dev = skb->dev;
+ if (dev)
+ skb->dev = NULL;
+
+ fq->q.stamp = skb->tstamp;
+ if (frag_type == LOWPAN_DISPATCH_FRAG1) {
+ /* Calculate uncomp. 6lowpan header to estimate full size */
+ fq->q.meat += lowpan_uncompress_size(skb, NULL);
+ fq->q.flags |= INET_FRAG_FIRST_IN;
+ } else {
+ fq->q.meat += skb->len;
+ }
+ add_frag_mem_limit(&fq->q, 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, prev, dev);
+ skb->_skb_refdst = orefdst;
+ return res;
+ }
+
+ return -1;
+err:
+ kfree_skb(skb);
+ return -1;
+}
+
+/* Check if this packet is complete.
+ * Returns NULL on failure by any reason, and pointer
+ * to current nexthdr field in reassembled frame.
+ *
+ * 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 *prev,
+ struct net_device *dev)
+{
+ struct sk_buff *fp, *head = fq->q.fragments;
+ int sum_truesize;
+
+ inet_frag_kill(&fq->q, &lowpan_frags);
+
+ /* Make the one we just received the head. */
+ if (prev) {
+ head = prev->next;
+ fp = skb_clone(head, GFP_ATOMIC);
+
+ if (!fp)
+ goto out_oom;
+
+ fp->next = head->next;
+ if (!fp->next)
+ fq->q.fragments_tail = fp;
+ prev->next = fp;
+
+ skb_morph(head, fq->q.fragments);
+ head->next = fq->q.fragments->next;
+
+ consume_skb(fq->q.fragments);
+ fq->q.fragments = head;
+ }
+
+ /* Head of list must not be cloned. */
+ if (skb_unclone(head, GFP_ATOMIC))
+ goto out_oom;
+
+ /* If the first fragment is fragmented itself, we split
+ * it to two chunks: the first with data and paged part
+ * and the second, holding only fragments.
+ */
+ if (skb_has_frag_list(head)) {
+ struct sk_buff *clone;
+ int i, plen = 0;
+
+ clone = alloc_skb(0, GFP_ATOMIC);
+ if (!clone)
+ goto out_oom;
+ clone->next = head->next;
+ head->next = clone;
+ skb_shinfo(clone)->frag_list = skb_shinfo(head)->frag_list;
+ skb_frag_list_init(head);
+ for (i = 0; i < skb_shinfo(head)->nr_frags; i++)
+ plen += skb_frag_size(&skb_shinfo(head)->frags[i]);
+ clone->len = head->data_len - plen;
+ clone->data_len = clone->len;
+ head->data_len -= clone->len;
+ head->len -= clone->len;
+ add_frag_mem_limit(&fq->q, clone->truesize);
+ }
+
+ WARN_ON(head == NULL);
+
+ sum_truesize = head->truesize;
+ for (fp = head->next; fp;) {
+ bool headstolen;
+ int delta;
+ struct sk_buff *next = fp->next;
+
+ sum_truesize += fp->truesize;
+ if (skb_try_coalesce(head, fp, &headstolen, &delta)) {
+ kfree_skb_partial(fp, headstolen);
+ } else {
+ if (!skb_shinfo(head)->frag_list)
+ skb_shinfo(head)->frag_list = fp;
+ head->data_len += fp->len;
+ head->len += fp->len;
+ head->truesize += fp->truesize;
+ }
+ fp = next;
+ }
+ sub_frag_mem_limit(&fq->q, sum_truesize);
+
+ head->next = NULL;
+ head->dev = dev;
+ head->tstamp = fq->q.stamp;
+
+ fq->q.fragments = NULL;
+ fq->q.fragments_tail = NULL;
+
+ return 1;
+out_oom:
+ net_dbg_ratelimited("lowpan_frag_reasm: no memory for reassembly\n");
+ return -1;
+}
+
+static int lowpan_get_frag_info(struct sk_buff *skb, const u8 frag_type,
+ struct lowpan_frag_info *frag_info)
+{
+ bool fail;
+ u8 pattern = 0, low = 0;
+ __be16 d_tag = 0;
+
+ fail = lowpan_fetch_skb(skb, &pattern, 1);
+ fail |= lowpan_fetch_skb(skb, &low, 1);
+ frag_info->d_size = (pattern & 7) << 8 | low;
+ fail |= lowpan_fetch_skb(skb, &d_tag, 2);
+ frag_info->d_tag = ntohs(d_tag);
+
+ if (frag_type == LOWPAN_DISPATCH_FRAGN) {
+ fail |= lowpan_fetch_skb(skb, &frag_info->d_offset, 1);
+ } else {
+ skb_reset_network_header(skb);
+ frag_info->d_offset = 0;
+ }
+
+ if (unlikely(fail))
+ return -EIO;
+
+ return 0;
+}
+
+int lowpan_frag_rcv(struct sk_buff *skb, const u8 frag_type)
+{
+ struct lowpan_frag_queue *fq;
+ struct net *net = dev_net(skb->dev);
+ struct lowpan_frag_info *frag_info = lowpan_cb(skb);
+ struct ieee802154_addr source, dest;
+ int err;
+
+ source = mac_cb(skb)->source;
+ dest = mac_cb(skb)->dest;
+
+ err = lowpan_get_frag_info(skb, frag_type, frag_info);
+ if (err < 0)
+ goto err;
+
+ if (frag_info->d_size > IPV6_MIN_MTU) {
+ net_warn_ratelimited("lowpan_frag_rcv: datagram size exceeds MTU\n");
+ goto err;
+ }
+
+ fq = fq_find(net, frag_info, &source, &dest);
+ if (fq != NULL) {
+ int ret;
+
+ spin_lock(&fq->q.lock);
+ ret = lowpan_frag_queue(fq, skb, frag_type);
+ spin_unlock(&fq->q.lock);
+
+ inet_frag_put(&fq->q, &lowpan_frags);
+ return ret;
+ }
+
+err:
+ kfree_skb(skb);
+ return -1;
+}
+EXPORT_SYMBOL(lowpan_frag_rcv);
+
+#ifdef CONFIG_SYSCTL
+static int zero;
+
+static struct ctl_table lowpan_frags_ns_ctl_table[] = {
+ {
+ .procname = "6lowpanfrag_high_thresh",
+ .data = &init_net.ieee802154_lowpan.frags.high_thresh,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = proc_dointvec_minmax,
+ .extra1 = &init_net.ieee802154_lowpan.frags.low_thresh
+ },
+ {
+ .procname = "6lowpanfrag_low_thresh",
+ .data = &init_net.ieee802154_lowpan.frags.low_thresh,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = proc_dointvec_minmax,
+ .extra1 = &zero,
+ .extra2 = &init_net.ieee802154_lowpan.frags.high_thresh
+ },
+ {
+ .procname = "6lowpanfrag_time",
+ .data = &init_net.ieee802154_lowpan.frags.timeout,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = proc_dointvec_jiffies,
+ },
+ { }
+};
+
+/* secret interval has been deprecated */
+static int lowpan_frags_secret_interval_unused;
+static struct ctl_table lowpan_frags_ctl_table[] = {
+ {
+ .procname = "6lowpanfrag_secret_interval",
+ .data = &lowpan_frags_secret_interval_unused,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = proc_dointvec_jiffies,
+ },
+ { }
+};
+
+static int __net_init lowpan_frags_ns_sysctl_register(struct net *net)
+{
+ struct ctl_table *table;
+ struct ctl_table_header *hdr;
+ struct netns_ieee802154_lowpan *ieee802154_lowpan =
+ net_ieee802154_lowpan(net);
+
+ table = lowpan_frags_ns_ctl_table;
+ if (!net_eq(net, &init_net)) {
+ table = kmemdup(table, sizeof(lowpan_frags_ns_ctl_table),
+ GFP_KERNEL);
+ if (table == NULL)
+ goto err_alloc;
+
+ table[0].data = &ieee802154_lowpan->frags.high_thresh;
+ table[0].extra1 = &ieee802154_lowpan->frags.low_thresh;
+ table[0].extra2 = &init_net.ieee802154_lowpan.frags.high_thresh;
+ table[1].data = &ieee802154_lowpan->frags.low_thresh;
+ table[1].extra2 = &ieee802154_lowpan->frags.high_thresh;
+ table[2].data = &ieee802154_lowpan->frags.timeout;
+
+ /* Don't export sysctls to unprivileged users */
+ if (net->user_ns != &init_user_ns)
+ table[0].procname = NULL;
+ }
+
+ hdr = register_net_sysctl(net, "net/ieee802154/6lowpan", table);
+ if (hdr == NULL)
+ goto err_reg;
+
+ ieee802154_lowpan->sysctl.frags_hdr = hdr;
+ return 0;
+
+err_reg:
+ if (!net_eq(net, &init_net))
+ kfree(table);
+err_alloc:
+ return -ENOMEM;
+}
+
+static void __net_exit lowpan_frags_ns_sysctl_unregister(struct net *net)
+{
+ struct ctl_table *table;
+ struct netns_ieee802154_lowpan *ieee802154_lowpan =
+ net_ieee802154_lowpan(net);
+
+ table = ieee802154_lowpan->sysctl.frags_hdr->ctl_table_arg;
+ unregister_net_sysctl_table(ieee802154_lowpan->sysctl.frags_hdr);
+ if (!net_eq(net, &init_net))
+ kfree(table);
+}
+
+static struct ctl_table_header *lowpan_ctl_header;
+
+static int __init lowpan_frags_sysctl_register(void)
+{
+ lowpan_ctl_header = register_net_sysctl(&init_net,
+ "net/ieee802154/6lowpan",
+ lowpan_frags_ctl_table);
+ return lowpan_ctl_header == NULL ? -ENOMEM : 0;
+}
+
+static void lowpan_frags_sysctl_unregister(void)
+{
+ unregister_net_sysctl_table(lowpan_ctl_header);
+}
+#else
+static inline int lowpan_frags_ns_sysctl_register(struct net *net)
+{
+ return 0;
+}
+
+static inline void lowpan_frags_ns_sysctl_unregister(struct net *net)
+{
+}
+
+static inline int __init lowpan_frags_sysctl_register(void)
+{
+ return 0;
+}
+
+static inline void lowpan_frags_sysctl_unregister(void)
+{
+}
+#endif
+
+static int __net_init lowpan_frags_init_net(struct net *net)
+{
+ struct netns_ieee802154_lowpan *ieee802154_lowpan =
+ net_ieee802154_lowpan(net);
+
+ ieee802154_lowpan->frags.high_thresh = IPV6_FRAG_HIGH_THRESH;
+ ieee802154_lowpan->frags.low_thresh = IPV6_FRAG_LOW_THRESH;
+ ieee802154_lowpan->frags.timeout = IPV6_FRAG_TIMEOUT;
+
+ inet_frags_init_net(&ieee802154_lowpan->frags);
+
+ return lowpan_frags_ns_sysctl_register(net);
+}
+
+static void __net_exit lowpan_frags_exit_net(struct net *net)
+{
+ struct netns_ieee802154_lowpan *ieee802154_lowpan =
+ net_ieee802154_lowpan(net);
+
+ lowpan_frags_ns_sysctl_unregister(net);
+ inet_frags_exit_net(&ieee802154_lowpan->frags, &lowpan_frags);
+}
+
+static struct pernet_operations lowpan_frags_ops = {
+ .init = lowpan_frags_init_net,
+ .exit = lowpan_frags_exit_net,
+};
+
+int __init lowpan_net_frag_init(void)
+{
+ int ret;
+
+ ret = lowpan_frags_sysctl_register();
+ if (ret)
+ return ret;
+
+ ret = register_pernet_subsys(&lowpan_frags_ops);
+ if (ret)
+ goto err_pernet;
+
+ lowpan_frags.hashfn = lowpan_hashfn;
+ lowpan_frags.constructor = lowpan_frag_init;
+ lowpan_frags.destructor = NULL;
+ lowpan_frags.skb_free = NULL;
+ lowpan_frags.qsize = sizeof(struct frag_queue);
+ lowpan_frags.match = lowpan_frag_match;
+ lowpan_frags.frag_expire = lowpan_frag_expire;
+ lowpan_frags.frags_cache_name = lowpan_frags_cache_name;
+ ret = inet_frags_init(&lowpan_frags);
+ if (ret)
+ goto err_pernet;
+
+ return ret;
+err_pernet:
+ lowpan_frags_sysctl_unregister();
+ return ret;
+}
+
+void lowpan_net_frag_exit(void)
+{
+ inet_frags_fini(&lowpan_frags);
+ lowpan_frags_sysctl_unregister();
+ unregister_pernet_subsys(&lowpan_frags_ops);
+}
Code Review / kvmfornfv.git / blobdiff