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net: ip: Handle delivery_time in ip defrag

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A latter patch will postpone the delivery_time clearing until the stack
knows the skb is being delivered locally.  That will allow other kernel
forwarding path (e.g. ip[6]_forward) to keep the delivery_time also.

An earlier attempt was to do skb_clear_delivery_time() in
ip_local_deliver() and ip6_input().  The discussion [0] requested
to move it one step later into ip_local_deliver_finish()
and ip6_input_finish() so that the delivery_time can be kept
for the ip_vs forwarding path also.

To do that, this patch also needs to take care of the (rcv) timestamp
usecase in ip_is_fragment().  It needs to expect delivery_time in
the skb->tstamp, so it needs to save the mono_delivery_time bit in
inet_frag_queue such that the delivery_time (if any) can be restored
in the final defragmented skb.

[Note that it will only happen when the locally generated skb is looping
 from egress to ingress over a virtual interface (e.g. veth, loopback...),
 skb->tstamp may have the delivery time before it is known that it will
 be delivered locally and received by another sk.]

[0]: https://lore.kernel.org/netdev/ca728d81-80e8-3767-d5e-d44f6ad96e43@ssi.bg/

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Martin KaFai Lau 2022-03-02 11:55:57 -08:00 committed by David S. Miller
parent d98d58a002
commit 8672406eb5
3 changed files with 4 additions and 0 deletions
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2
include/net/inet_frag.h
View file

@ -70,6 +70,7 @@ struct frag_v6_compare_key {
* @stamp: timestamp of the last received fragment
* @len: total length of the original datagram
* @meat: length of received fragments so far
* @mono_delivery_time: stamp has a mono delivery time (EDT)
* @flags: fragment queue flags
* @max_size: maximum received fragment size
* @fqdir: pointer to struct fqdir
@ -90,6 +91,7 @@ struct inet_frag_queue {
ktime_t stamp;
int len;
int meat;
u8 mono_delivery_time;
__u8 flags;
u16 max_size;
struct fqdir *fqdir;

1
net/ipv4/inet_fragment.c
View file

@ -572,6 +572,7 @@ void inet_frag_reasm_finish(struct inet_frag_queue *q, struct sk_buff *head,
skb_mark_not_on_list(head);
head->prev = NULL;
head->tstamp = q->stamp;
head->mono_delivery_time = q->mono_delivery_time;
}
EXPORT_SYMBOL(inet_frag_reasm_finish);

1
net/ipv4/ip_fragment.c
View file

@ -349,6 +349,7 @@ static int ip_frag_queue(struct ipq *qp, struct sk_buff *skb)
qp->iif = dev->ifindex;
qp->q.stamp = skb->tstamp;
qp->q.mono_delivery_time = skb->mono_delivery_time;
qp->q.meat += skb->len;
qp->ecn |= ecn;
add_frag_mem_limit(qp->q.fqdir, skb->truesize);