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tipc: buffer overflow handling in listener socket

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Default socket receive buffer size for a listener socket is 2Mb. For
each arriving empty SYN, the linux kernel allocates a 768 bytes buffer.
This means that a listener socket can serve maximum 2700 simultaneous
empty connection setup requests before it hits a receive buffer
overflow, and much fewer if the SYN is carrying any significant
amount of data.

When this happens the setup request is rejected, and the client
receives an ECONNREFUSED error.

This commit mitigates this problem by letting the client socket try to
retransmit the SYN message multiple times when it sees it rejected with
the code TIPC_ERR_OVERLOAD. Retransmission is done at random intervals
in the range of [100 ms, setup_timeout / 4], as many times as there is
room for within the setup timeout limit.

Signed-off-by: Tung Nguyen <tung.q.nguyen@dektech.com.au>
Acked-by: Ying Xue <ying.xue@windriver.com>
Signed-off-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Tung Nguyen
2018-09-28 20:23:22 +02:00
committed by David S. Miller
parent 25b9221b95
commit 6787927475
3 changed files with 64 additions and 6 deletions
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20
net/tipc/msg.c
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@@ -525,6 +525,10 @@ bool tipc_msg_reverse(u32 own_node, struct sk_buff **skb, int err)
if (hlen == SHORT_H_SIZE)
hlen = BASIC_H_SIZE;
/* Don't return data along with SYN+, - sender has a clone */
if (msg_is_syn(_hdr) && err == TIPC_ERR_OVERLOAD)
dlen = 0;
/* Allocate new buffer to return */
*skb = tipc_buf_acquire(hlen + dlen, GFP_ATOMIC);
if (!*skb)
@@ -552,6 +556,22 @@ exit:
return false;
}
bool tipc_msg_skb_clone(struct sk_buff_head *msg, struct sk_buff_head *cpy)
{
struct sk_buff *skb, *_skb;
skb_queue_walk(msg, skb) {
_skb = skb_clone(skb, GFP_ATOMIC);
if (!_skb) {
__skb_queue_purge(cpy);
pr_err_ratelimited("Failed to clone buffer chain\n");
return false;
}
__skb_queue_tail(cpy, _skb);
}
return true;
}
/**
* tipc_msg_lookup_dest(): try to find new destination for named message
* @skb: the buffer containing the message.