net: IP6 defrag: use rbtrees for IPv6 defrag
Currently, IPv6 defragmentation code drops non-last fragments that
are smaller than 1280 bytes: see
commit 0ed4229b08 ("ipv6: defrag: drop non-last frags smaller than min mtu")
This behavior is not specified in IPv6 RFCs and appears to break
compatibility with some IPv6 implemenations, as reported here:
https://www.spinics.net/lists/netdev/msg543846.html
This patch re-uses common IP defragmentation queueing and reassembly
code in IPv6, removing the 1280 byte restriction.
Signed-off-by: Peter Oskolkov <posk@google.com>
Reported-by: Tom Herbert <tom@herbertland.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Peter Oskolkov
David S. Miller
Родитель
c23f35d19d
Коммит
d4289fcc9b
|
|
@ -82,8 +82,15 @@ ip6frag_expire_frag_queue(struct net *net, struct frag_queue *fq)
|
|||
__IP6_INC_STATS(net, __in6_dev_get(dev), IPSTATS_MIB_REASMTIMEOUT);
|
||||
|
||||
/* Don't send error if the first segment did not arrive. */
|
||||
head = fq->q.fragments;
|
||||
if (!(fq->q.flags & INET_FRAG_FIRST_IN) || !head)
|
||||
if (!(fq->q.flags & INET_FRAG_FIRST_IN))
|
||||
goto out;
|
||||
|
||||
/* sk_buff::dev and sk_buff::rbnode are unionized. So we
|
||||
* pull the head out of the tree in order to be able to
|
||||
* deal with head->dev.
|
||||
*/
|
||||
head = inet_frag_pull_head(&fq->q);
|
||||
if (!head)
|
||||
goto out;
|
||||
|
||||
head->dev = dev;
|
||||
|
|
|
|||
|
|
@ -69,8 +69,8 @@ static u8 ip6_frag_ecn(const struct ipv6hdr *ipv6h)
|
|||
|
||||
static struct inet_frags ip6_frags;
|
||||
|
||||
static int ip6_frag_reasm(struct frag_queue *fq, struct sk_buff *prev,
|
||||
struct net_device *dev);
|
||||
static int ip6_frag_reasm(struct frag_queue *fq, struct sk_buff *skb,
|
||||
struct sk_buff *prev_tail, struct net_device *dev);
|
||||
|
||||
static void ip6_frag_expire(struct timer_list *t)
|
||||
{
|
||||
|
|
@ -111,21 +111,26 @@ static int ip6_frag_queue(struct frag_queue *fq, struct sk_buff *skb,
|
|||
struct frag_hdr *fhdr, int nhoff,
|
||||
u32 *prob_offset)
|
||||
{
|
||||
struct sk_buff *prev, *next;
|
||||
struct net_device *dev;
|
||||
int offset, end, fragsize;
|
||||
struct net *net = dev_net(skb_dst(skb)->dev);
|
||||
int offset, end, fragsize;
|
||||
struct sk_buff *prev_tail;
|
||||
struct net_device *dev;
|
||||
int err = -ENOENT;
|
||||
u8 ecn;
|
||||
|
||||
if (fq->q.flags & INET_FRAG_COMPLETE)
|
||||
goto err;
|
||||
|
||||
err = -EINVAL;
|
||||
offset = ntohs(fhdr->frag_off) & ~0x7;
|
||||
end = offset + (ntohs(ipv6_hdr(skb)->payload_len) -
|
||||
((u8 *)(fhdr + 1) - (u8 *)(ipv6_hdr(skb) + 1)));
|
||||
|
||||
if ((unsigned int)end > IPV6_MAXPLEN) {
|
||||
*prob_offset = (u8 *)&fhdr->frag_off - skb_network_header(skb);
|
||||
/* note that if prob_offset is set, the skb is freed elsewhere,
|
||||
* we do not free it here.
|
||||
*/
|
||||
return -1;
|
||||
}
|
||||
|
||||
|
|
@ -170,62 +175,27 @@ static int ip6_frag_queue(struct frag_queue *fq, struct sk_buff *skb,
|
|||
if (end == offset)
|
||||
goto discard_fq;
|
||||
|
||||
err = -ENOMEM;
|
||||
/* Point into the IP datagram 'data' part. */
|
||||
if (!pskb_pull(skb, (u8 *) (fhdr + 1) - skb->data))
|
||||
goto discard_fq;
|
||||
|
||||
if (pskb_trim_rcsum(skb, end - offset))
|
||||
err = pskb_trim_rcsum(skb, end - offset);
|
||||
if (err)
|
||||
goto discard_fq;
|
||||
|
||||
/* 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 || prev->ip_defrag_offset < offset) {
|
||||
next = NULL;
|
||||
goto found;
|
||||
}
|
||||
prev = NULL;
|
||||
for (next = fq->q.fragments; next != NULL; next = next->next) {
|
||||
if (next->ip_defrag_offset >= offset)
|
||||
break; /* bingo! */
|
||||
prev = next;
|
||||
}
|
||||
|
||||
found:
|
||||
/* RFC5722, Section 4, amended by Errata ID : 3089
|
||||
* When reassembling an IPv6 datagram, if
|
||||
* one or more its constituent fragments is determined to be an
|
||||
* overlapping fragment, the entire datagram (and any constituent
|
||||
* fragments) MUST be silently discarded.
|
||||
*/
|
||||
|
||||
/* Check for overlap with preceding fragment. */
|
||||
if (prev &&
|
||||
(prev->ip_defrag_offset + prev->len) > offset)
|
||||
goto discard_fq;
|
||||
|
||||
/* Look for overlap with succeeding segment. */
|
||||
if (next && next->ip_defrag_offset < end)
|
||||
goto discard_fq;
|
||||
|
||||
/* Note : skb->ip_defrag_offset and skb->sk share the same location */
|
||||
/* Note : skb->rbnode and skb->dev share the same location. */
|
||||
dev = skb->dev;
|
||||
if (dev)
|
||||
fq->iif = dev->ifindex;
|
||||
/* Makes sure compiler wont do silly aliasing games */
|
||||
barrier();
|
||||
skb->ip_defrag_offset = offset;
|
||||
|
||||
/* 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;
|
||||
prev_tail = fq->q.fragments_tail;
|
||||
err = inet_frag_queue_insert(&fq->q, skb, offset, end);
|
||||
if (err)
|
||||
goto insert_error;
|
||||
|
||||
if (dev)
|
||||
fq->iif = dev->ifindex;
|
||||
|
||||
fq->q.stamp = skb->tstamp;
|
||||
fq->q.meat += skb->len;
|
||||
|
|
@ -246,44 +216,48 @@ found:
|
|||
|
||||
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 = ip6_frag_reasm(fq, prev, dev);
|
||||
err = ip6_frag_reasm(fq, skb, prev_tail, dev);
|
||||
skb->_skb_refdst = orefdst;
|
||||
return res;
|
||||
return err;
|
||||
}
|
||||
|
||||
skb_dst_drop(skb);
|
||||
return -1;
|
||||
return -EINPROGRESS;
|
||||
|
||||
insert_error:
|
||||
if (err == IPFRAG_DUP) {
|
||||
kfree_skb(skb);
|
||||
return -EINVAL;
|
||||
}
|
||||
err = -EINVAL;
|
||||
__IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
|
||||
IPSTATS_MIB_REASM_OVERLAPS);
|
||||
discard_fq:
|
||||
inet_frag_kill(&fq->q);
|
||||
err:
|
||||
__IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
|
||||
IPSTATS_MIB_REASMFAILS);
|
||||
err:
|
||||
kfree_skb(skb);
|
||||
return -1;
|
||||
return err;
|
||||
}
|
||||
|
||||
/*
|
||||
* 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 ip6_frag_reasm(struct frag_queue *fq, struct sk_buff *prev,
|
||||
struct net_device *dev)
|
||||
static int ip6_frag_reasm(struct frag_queue *fq, struct sk_buff *skb,
|
||||
struct sk_buff *prev_tail, struct net_device *dev)
|
||||
{
|
||||
struct net *net = container_of(fq->q.net, struct net, ipv6.frags);
|
||||
struct sk_buff *fp, *head = fq->q.fragments;
|
||||
int payload_len, delta;
|
||||
unsigned int nhoff;
|
||||
int sum_truesize;
|
||||
void *reasm_data;
|
||||
int payload_len;
|
||||
u8 ecn;
|
||||
|
||||
inet_frag_kill(&fq->q);
|
||||
|
|
@ -292,121 +266,40 @@ static int ip6_frag_reasm(struct frag_queue *fq, struct sk_buff *prev,
|
|||
if (unlikely(ecn == 0xff))
|
||||
goto out_fail;
|
||||
|
||||
/* Make the one we just received the head. */
|
||||
if (prev) {
|
||||
head = prev->next;
|
||||
fp = skb_clone(head, GFP_ATOMIC);
|
||||
|
||||
if (!fp)
|
||||
reasm_data = inet_frag_reasm_prepare(&fq->q, skb, prev_tail);
|
||||
if (!reasm_data)
|
||||
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;
|
||||
}
|
||||
|
||||
WARN_ON(head == NULL);
|
||||
WARN_ON(head->ip_defrag_offset != 0);
|
||||
|
||||
/* Unfragmented part is taken from the first segment. */
|
||||
payload_len = ((head->data - skb_network_header(head)) -
|
||||
payload_len = ((skb->data - skb_network_header(skb)) -
|
||||
sizeof(struct ipv6hdr) + fq->q.len -
|
||||
sizeof(struct frag_hdr));
|
||||
if (payload_len > IPV6_MAXPLEN)
|
||||
goto out_oversize;
|
||||
|
||||
delta = - head->truesize;
|
||||
|
||||
/* Head of list must not be cloned. */
|
||||
if (skb_unclone(head, GFP_ATOMIC))
|
||||
goto out_oom;
|
||||
|
||||
delta += head->truesize;
|
||||
if (delta)
|
||||
add_frag_mem_limit(fq->q.net, delta);
|
||||
|
||||
/* 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 = clone->data_len = head->data_len - plen;
|
||||
head->data_len -= clone->len;
|
||||
head->len -= clone->len;
|
||||
clone->csum = 0;
|
||||
clone->ip_summed = head->ip_summed;
|
||||
add_frag_mem_limit(fq->q.net, clone->truesize);
|
||||
}
|
||||
|
||||
/* We have to remove fragment header from datagram and to relocate
|
||||
* header in order to calculate ICV correctly. */
|
||||
nhoff = fq->nhoffset;
|
||||
skb_network_header(head)[nhoff] = skb_transport_header(head)[0];
|
||||
memmove(head->head + sizeof(struct frag_hdr), head->head,
|
||||
(head->data - head->head) - sizeof(struct frag_hdr));
|
||||
if (skb_mac_header_was_set(head))
|
||||
head->mac_header += sizeof(struct frag_hdr);
|
||||
head->network_header += sizeof(struct frag_hdr);
|
||||
skb_network_header(skb)[nhoff] = skb_transport_header(skb)[0];
|
||||
memmove(skb->head + sizeof(struct frag_hdr), skb->head,
|
||||
(skb->data - skb->head) - sizeof(struct frag_hdr));
|
||||
if (skb_mac_header_was_set(skb))
|
||||
skb->mac_header += sizeof(struct frag_hdr);
|
||||
skb->network_header += sizeof(struct frag_hdr);
|
||||
|
||||
skb_reset_transport_header(head);
|
||||
skb_push(head, head->data - skb_network_header(head));
|
||||
skb_reset_transport_header(skb);
|
||||
|
||||
sum_truesize = head->truesize;
|
||||
for (fp = head->next; fp;) {
|
||||
bool headstolen;
|
||||
int delta;
|
||||
struct sk_buff *next = fp->next;
|
||||
inet_frag_reasm_finish(&fq->q, skb, reasm_data);
|
||||
|
||||
sum_truesize += fp->truesize;
|
||||
if (head->ip_summed != fp->ip_summed)
|
||||
head->ip_summed = CHECKSUM_NONE;
|
||||
else if (head->ip_summed == CHECKSUM_COMPLETE)
|
||||
head->csum = csum_add(head->csum, fp->csum);
|
||||
|
||||
if (skb_try_coalesce(head, fp, &headstolen, &delta)) {
|
||||
kfree_skb_partial(fp, headstolen);
|
||||
} else {
|
||||
fp->sk = NULL;
|
||||
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);
|
||||
|
||||
skb_mark_not_on_list(head);
|
||||
head->dev = dev;
|
||||
head->tstamp = fq->q.stamp;
|
||||
ipv6_hdr(head)->payload_len = htons(payload_len);
|
||||
ipv6_change_dsfield(ipv6_hdr(head), 0xff, ecn);
|
||||
IP6CB(head)->nhoff = nhoff;
|
||||
IP6CB(head)->flags |= IP6SKB_FRAGMENTED;
|
||||
IP6CB(head)->frag_max_size = fq->q.max_size;
|
||||
skb->dev = dev;
|
||||
ipv6_hdr(skb)->payload_len = htons(payload_len);
|
||||
ipv6_change_dsfield(ipv6_hdr(skb), 0xff, ecn);
|
||||
IP6CB(skb)->nhoff = nhoff;
|
||||
IP6CB(skb)->flags |= IP6SKB_FRAGMENTED;
|
||||
IP6CB(skb)->frag_max_size = fq->q.max_size;
|
||||
|
||||
/* Yes, and fold redundant checksum back. 8) */
|
||||
skb_postpush_rcsum(head, skb_network_header(head),
|
||||
skb_network_header_len(head));
|
||||
skb_postpush_rcsum(skb, skb_network_header(skb),
|
||||
skb_network_header_len(skb));
|
||||
|
||||
rcu_read_lock();
|
||||
__IP6_INC_STATS(net, __in6_dev_get(dev), IPSTATS_MIB_REASMOKS);
|
||||
|
|
@ -414,6 +307,7 @@ static int ip6_frag_reasm(struct frag_queue *fq, struct sk_buff *prev,
|
|||
fq->q.fragments = NULL;
|
||||
fq->q.rb_fragments = RB_ROOT;
|
||||
fq->q.fragments_tail = NULL;
|
||||
fq->q.last_run_head = NULL;
|
||||
return 1;
|
||||
|
||||
out_oversize:
|
||||
|
|
@ -464,10 +358,6 @@ static int ipv6_frag_rcv(struct sk_buff *skb)
|
|||
return 1;
|
||||
}
|
||||
|
||||
if (skb->len - skb_network_offset(skb) < IPV6_MIN_MTU &&
|
||||
fhdr->frag_off & htons(IP6_MF))
|
||||
goto fail_hdr;
|
||||
|
||||
iif = skb->dev ? skb->dev->ifindex : 0;
|
||||
fq = fq_find(net, fhdr->identification, hdr, iif);
|
||||
if (fq) {
|
||||
|
|
@ -485,6 +375,7 @@ static int ipv6_frag_rcv(struct sk_buff *skb)
|
|||
if (prob_offset) {
|
||||
__IP6_INC_STATS(net, __in6_dev_get_safely(skb->dev),
|
||||
IPSTATS_MIB_INHDRERRORS);
|
||||
/* icmpv6_param_prob() calls kfree_skb(skb) */
|
||||
icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, prob_offset);
|
||||
}
|
||||
return ret;
|
||||
|
|
|
|||
Загрузка…
Ссылка в новой задаче