From 4a5409a5a850c84505d658ddf36f98b2c542ec07 Mon Sep 17 00:00:00 2001 From: Gerrit Renker Date: Thu, 4 Oct 2007 14:52:28 -0700 Subject: [PATCH] [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 Signed-off-by: Ian McDonald Signed-off-by: Arnaldo Carvalho de Melo Signed-off-by: David S. Miller --- net/dccp/ipv4.c | 11 ++++------- net/dccp/ipv6.c | 7 +++---- 2 files changed, 7 insertions(+), 11 deletions(-) diff --git a/net/dccp/ipv4.c b/net/dccp/ipv4.c index 2312b9f4d7af..44f6e17e105f 100644 --- a/net/dccp/ipv4.c +++ b/net/dccp/ipv4.c @@ -568,17 +568,14 @@ int dccp_v4_conn_request(struct sock *sk, struct sk_buff *skb) 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; } /* @@ -586,6 +583,7 @@ int dccp_v4_conn_request(struct sock *sk, struct sk_buff *skb) * 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; @@ -638,7 +636,6 @@ drop_and_free: reqsk_free(req); drop: DCCP_INC_STATS_BH(DCCP_MIB_ATTEMPTFAILS); - dcb->dccpd_reset_code = reset_code; return -1; } diff --git a/net/dccp/ipv6.c b/net/dccp/ipv6.c index b7c0f66e2834..006a3834fbcd 100644 --- a/net/dccp/ipv6.c +++ b/net/dccp/ipv6.c @@ -390,21 +390,21 @@ static int dccp_v6_conn_request(struct sock *sk, struct sk_buff *skb) 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; @@ -464,7 +464,6 @@ drop_and_free: reqsk_free(req); drop: DCCP_INC_STATS_BH(DCCP_MIB_ATTEMPTFAILS); - dcb->dccpd_reset_code = reset_code; return -1; } -- 2.39.5