[DCCP]: Twice the wrong reset code in receiving connection-Requests
This fixes two bugs in processing of connection-Requests in v{4,6}_conn_request:
1. Due to using the variable `reset_code', the Reset code generated internally
by dccp_parse_options() is overwritten with the initialised value ("Too Busy")
of reset_code, which is not what is intended.
2. When receiving a connection-Request on a multicast or broadcast address, no
Reset should be generated, to avoid storms of such packets. Instead of jumping
to the `drop' label, the v{4,6}_conn_request functions now return 0. Below is
why in my understanding this is correct:
When the conn_request function returns < 0, then the caller, dccp_rcv_state_process(),
returns 1. In all instances where dccp_rcv_state_process is called (dccp_v4_do_rcv,
dccp_v6_do_rcv, and dccp_child_process), a return value of != 0 from dccp_rcv_state_process()
means that a Reset is generated.
If on the other hand the conn_request function returns 0, the packet is discarded and no
Reset is generated.
Note: There may be a related problem when sending the Response, due to the following.
if (dccp_v6_send_response(sk, req, NULL))
goto drop_and_free;
/* ... */
drop_and_free:
return -1;
In this case, if send_response fails due to transmission errors, the next thing that is
generated is a Reset with a code "Too Busy". I haven't been able to conjure up such a
condition, but it might be good to change the behaviour here also (not done by this patch).
Signed-off-by: Gerrit Renker <gerrit@xxxxxxxxxxxxxx>
---
net/dccp/ipv4.c | 11 ++++-------
net/dccp/ipv6.c | 7 +++----
2 files changed, 7 insertions(+), 11 deletions(-)
--- a/net/dccp/ipv4.c
+++ b/net/dccp/ipv4.c
@@ -598,17 +598,14 @@ int dccp_v4_conn_request(struct sock *sk
struct dccp_request_sock *dreq;
const __be32 service = dccp_hdr_request(skb)->dccph_req_service;
struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
- __u8 reset_code = DCCP_RESET_CODE_TOO_BUSY;
/* Never answer to DCCP_PKT_REQUESTs send to broadcast or multicast */
if (((struct rtable *)skb->dst)->rt_flags &
- (RTCF_BROADCAST | RTCF_MULTICAST)) {
- reset_code = DCCP_RESET_CODE_NO_CONNECTION;
- goto drop;
- }
+ (RTCF_BROADCAST | RTCF_MULTICAST))
+ return 0; /* discard, don't send a reset here */
if (dccp_bad_service_code(sk, service)) {
- reset_code = DCCP_RESET_CODE_BAD_SERVICE_CODE;
+ dcb->dccpd_reset_code = DCCP_RESET_CODE_BAD_SERVICE_CODE;
goto drop;
}
/*
@@ -616,6 +613,7 @@ int dccp_v4_conn_request(struct sock *sk
* limitations, they conserve resources and peer is
* evidently real one.
*/
+ dcb->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY;
if (inet_csk_reqsk_queue_is_full(sk))
goto drop;
@@ -668,7 +666,6 @@ drop_and_free:
reqsk_free(req);
drop:
DCCP_INC_STATS_BH(DCCP_MIB_ATTEMPTFAILS);
- dcb->dccpd_reset_code = reset_code;
return -1;
}
--- a/net/dccp/ipv6.c
+++ b/net/dccp/ipv6.c
@@ -417,21 +417,21 @@ static int dccp_v6_conn_request(struct s
struct ipv6_pinfo *np = inet6_sk(sk);
const __be32 service = dccp_hdr_request(skb)->dccph_req_service;
struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
- __u8 reset_code = DCCP_RESET_CODE_TOO_BUSY;
if (skb->protocol == htons(ETH_P_IP))
return dccp_v4_conn_request(sk, skb);
if (!ipv6_unicast_destination(skb))
- goto drop;
+ return 0; /* discard, don't send a reset here */
if (dccp_bad_service_code(sk, service)) {
- reset_code = DCCP_RESET_CODE_BAD_SERVICE_CODE;
+ dcb->dccpd_reset_code = DCCP_RESET_CODE_BAD_SERVICE_CODE;
goto drop;
}
/*
* There are no SYN attacks on IPv6, yet...
*/
+ dcb->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY;
if (inet_csk_reqsk_queue_is_full(sk))
goto drop;
@@ -491,7 +491,6 @@ drop_and_free:
reqsk_free(req);
drop:
DCCP_INC_STATS_BH(DCCP_MIB_ATTEMPTFAILS);
- dcb->dccpd_reset_code = reset_code;
return -1;
}
-
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