- 根目录:
- net
- ieee802154
- 6lowpan
- reassembly.c
/* 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";
static struct inet_frags lowpan_frags;
static int lowpan_frag_reasm(struct lowpan_frag_queue *fq,
struct sk_buff *prev, struct net_device *ldev);
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_802154_cb *cb,
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 = cb->d_tag;
arg.d_size = cb->d_size;
arg.src = src;
arg.dst = dst;
hash = lowpan_hash_frag(cb->d_tag, cb->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, u8 frag_type)
{
struct sk_buff *prev, *next;
struct net_device *ldev;
int end, offset;
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;
}
}
/* 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_802154_cb(prev)->d_offset <
lowpan_802154_cb(skb)->d_offset) {
next = NULL;
goto found;
}
prev = NULL;
for (next = fq->q.fragments; next != NULL; next = next->next) {
if (lowpan_802154_cb(next)->d_offset >=
lowpan_802154_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;
ldev = skb->dev;
if (ldev)
skb->dev = NULL;
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.net, 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, ldev);
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 *ldev)
{
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.net, 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.net, sum_truesize);
head->next = NULL;
head->dev = ldev;
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_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 frag_type,
struct lowpan_802154_cb *cb)
{
bool fail;
u8 high = 0, low = 0;
__be16 d_tag = 0;
fail = lowpan_fetch_skb(skb, &high, 1);
fail |= lowpan_fetch_skb(skb, &low, 1);
/* remove the dispatch value and use first three bits as high value
* for the datagram size
*/
cb->d_size = (high & LOWPAN_FRAG_DGRAM_SIZE_HIGH_MASK) <<
LOWPAN_FRAG_DGRAM_SIZE_HIGH_SHIFT | low;
fail |= lowpan_fetch_skb(skb, &d_tag, 2);
cb->d_tag = ntohs(d_tag);
if (frag_type == LOWPAN_DISPATCH_FRAGN) {
fail |= lowpan_fetch_skb(skb, &cb->d_offset, 1);
} else {
skb_reset_network_header(skb);
cb->d_offset = 0;
/* check if datagram_size has ipv6hdr on FRAG1 */
fail |= cb->d_size < sizeof(struct ipv6hdr);
/* check if we can dereference the dispatch value */
fail |= !skb->len;
}
if (unlikely(fail))
return -EIO;
return 0;
}
int lowpan_frag_rcv(struct sk_buff *skb, u8 frag_type)
{
struct lowpan_frag_queue *fq;
struct net *net = dev_net(skb->dev);
struct lowpan_802154_cb *cb = lowpan_802154_cb(skb);
struct ieee802154_hdr hdr;
int err;
if (ieee802154_hdr_peek_addrs(skb, &hdr) < 0)
goto err;
err = lowpan_get_cb(skb, frag_type, cb);
if (err < 0)
goto err;
if (frag_type == LOWPAN_DISPATCH_FRAG1) {
err = lowpan_invoke_frag_rx_handlers(skb);
if (err == NET_RX_DROP)
goto err;
}
if (cb->d_size > IPV6_MIN_MTU) {
net_warn_ratelimited("lowpan_frag_rcv: datagram size exceeds MTU\n");
goto err;
}
fq = fq_find(net, cb, &hdr.source, &hdr.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;
}
#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);
int res;
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;
res = inet_frags_init_net(&ieee802154_lowpan->frags);
if (res)
return res;
res = lowpan_frags_ns_sysctl_register(net);
if (res)
inet_frags_uninit_net(&ieee802154_lowpan->frags);
return res;
}
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);
}