kernel-fxtec-pro1x/net/dccp/ipv4.c
Hannes Frederic Sowa 482fc6094a ipv4: introduce new IP_MTU_DISCOVER mode IP_PMTUDISC_INTERFACE
Sockets marked with IP_PMTUDISC_INTERFACE won't do path mtu discovery,
their sockets won't accept and install new path mtu information and they
will always use the interface mtu for outgoing packets. It is guaranteed
that the packet is not fragmented locally. But we won't set the DF-Flag
on the outgoing frames.

Florian Weimer had the idea to use this flag to ensure DNS servers are
never generating outgoing fragments. They may well be fragmented on the
path, but the server never stores or usees path mtu values, which could
well be forged in an attack.

(The root of the problem with path MTU discovery is that there is
no reliable way to authenticate ICMP Fragmentation Needed But DF Set
messages because they are sent from intermediate routers with their
source addresses, and the IMCP payload will not always contain sufficient
information to identify a flow.)

Recent research in the DNS community showed that it is possible to
implement an attack where DNS cache poisoning is feasible by spoofing
fragments. This work was done by Amir Herzberg and Haya Shulman:
<https://sites.google.com/site/hayashulman/files/fragmentation-poisoning.pdf>

This issue was previously discussed among the DNS community, e.g.
<http://www.ietf.org/mail-archive/web/dnsext/current/msg01204.html>,
without leading to fixes.

This patch depends on the patch "ipv4: fix DO and PROBE pmtu mode
regarding local fragmentation with UFO/CORK" for the enforcement of the
non-fragmentable checks. If other users than ip_append_page/data should
use this semantic too, we have to add a new flag to IPCB(skb)->flags to
suppress local fragmentation and check for this in ip_finish_output.

Many thanks to Florian Weimer for the idea and feedback while implementing
this patch.

Cc: David S. Miller <davem@davemloft.net>
Suggested-by: Florian Weimer <fweimer@redhat.com>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2013-11-05 21:52:27 -05:00

1095 lines
28 KiB
C

/*
* net/dccp/ipv4.c
*
* An implementation of the DCCP protocol
* Arnaldo Carvalho de Melo <acme@conectiva.com.br>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <linux/dccp.h>
#include <linux/icmp.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/random.h>
#include <net/icmp.h>
#include <net/inet_common.h>
#include <net/inet_hashtables.h>
#include <net/inet_sock.h>
#include <net/protocol.h>
#include <net/sock.h>
#include <net/timewait_sock.h>
#include <net/tcp_states.h>
#include <net/xfrm.h>
#include <net/secure_seq.h>
#include "ackvec.h"
#include "ccid.h"
#include "dccp.h"
#include "feat.h"
/*
* The per-net dccp.v4_ctl_sk socket is used for responding to
* the Out-of-the-blue (OOTB) packets. A control sock will be created
* for this socket at the initialization time.
*/
int dccp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
{
const struct sockaddr_in *usin = (struct sockaddr_in *)uaddr;
struct inet_sock *inet = inet_sk(sk);
struct dccp_sock *dp = dccp_sk(sk);
__be16 orig_sport, orig_dport;
__be32 daddr, nexthop;
struct flowi4 *fl4;
struct rtable *rt;
int err;
struct ip_options_rcu *inet_opt;
dp->dccps_role = DCCP_ROLE_CLIENT;
if (addr_len < sizeof(struct sockaddr_in))
return -EINVAL;
if (usin->sin_family != AF_INET)
return -EAFNOSUPPORT;
nexthop = daddr = usin->sin_addr.s_addr;
inet_opt = rcu_dereference_protected(inet->inet_opt,
sock_owned_by_user(sk));
if (inet_opt != NULL && inet_opt->opt.srr) {
if (daddr == 0)
return -EINVAL;
nexthop = inet_opt->opt.faddr;
}
orig_sport = inet->inet_sport;
orig_dport = usin->sin_port;
fl4 = &inet->cork.fl.u.ip4;
rt = ip_route_connect(fl4, nexthop, inet->inet_saddr,
RT_CONN_FLAGS(sk), sk->sk_bound_dev_if,
IPPROTO_DCCP,
orig_sport, orig_dport, sk, true);
if (IS_ERR(rt))
return PTR_ERR(rt);
if (rt->rt_flags & (RTCF_MULTICAST | RTCF_BROADCAST)) {
ip_rt_put(rt);
return -ENETUNREACH;
}
if (inet_opt == NULL || !inet_opt->opt.srr)
daddr = fl4->daddr;
if (inet->inet_saddr == 0)
inet->inet_saddr = fl4->saddr;
inet->inet_rcv_saddr = inet->inet_saddr;
inet->inet_dport = usin->sin_port;
inet->inet_daddr = daddr;
inet_csk(sk)->icsk_ext_hdr_len = 0;
if (inet_opt)
inet_csk(sk)->icsk_ext_hdr_len = inet_opt->opt.optlen;
/*
* Socket identity is still unknown (sport may be zero).
* However we set state to DCCP_REQUESTING and not releasing socket
* lock select source port, enter ourselves into the hash tables and
* complete initialization after this.
*/
dccp_set_state(sk, DCCP_REQUESTING);
err = inet_hash_connect(&dccp_death_row, sk);
if (err != 0)
goto failure;
rt = ip_route_newports(fl4, rt, orig_sport, orig_dport,
inet->inet_sport, inet->inet_dport, sk);
if (IS_ERR(rt)) {
err = PTR_ERR(rt);
rt = NULL;
goto failure;
}
/* OK, now commit destination to socket. */
sk_setup_caps(sk, &rt->dst);
dp->dccps_iss = secure_dccp_sequence_number(inet->inet_saddr,
inet->inet_daddr,
inet->inet_sport,
inet->inet_dport);
inet->inet_id = dp->dccps_iss ^ jiffies;
err = dccp_connect(sk);
rt = NULL;
if (err != 0)
goto failure;
out:
return err;
failure:
/*
* This unhashes the socket and releases the local port, if necessary.
*/
dccp_set_state(sk, DCCP_CLOSED);
ip_rt_put(rt);
sk->sk_route_caps = 0;
inet->inet_dport = 0;
goto out;
}
EXPORT_SYMBOL_GPL(dccp_v4_connect);
/*
* This routine does path mtu discovery as defined in RFC1191.
*/
static inline void dccp_do_pmtu_discovery(struct sock *sk,
const struct iphdr *iph,
u32 mtu)
{
struct dst_entry *dst;
const struct inet_sock *inet = inet_sk(sk);
const struct dccp_sock *dp = dccp_sk(sk);
/* We are not interested in DCCP_LISTEN and request_socks (RESPONSEs
* send out by Linux are always < 576bytes so they should go through
* unfragmented).
*/
if (sk->sk_state == DCCP_LISTEN)
return;
dst = inet_csk_update_pmtu(sk, mtu);
if (!dst)
return;
/* Something is about to be wrong... Remember soft error
* for the case, if this connection will not able to recover.
*/
if (mtu < dst_mtu(dst) && ip_dont_fragment(sk, dst))
sk->sk_err_soft = EMSGSIZE;
mtu = dst_mtu(dst);
if (inet->pmtudisc != IP_PMTUDISC_DONT &&
ip_sk_accept_pmtu(sk) &&
inet_csk(sk)->icsk_pmtu_cookie > mtu) {
dccp_sync_mss(sk, mtu);
/*
* From RFC 4340, sec. 14.1:
*
* DCCP-Sync packets are the best choice for upward
* probing, since DCCP-Sync probes do not risk application
* data loss.
*/
dccp_send_sync(sk, dp->dccps_gsr, DCCP_PKT_SYNC);
} /* else let the usual retransmit timer handle it */
}
static void dccp_do_redirect(struct sk_buff *skb, struct sock *sk)
{
struct dst_entry *dst = __sk_dst_check(sk, 0);
if (dst)
dst->ops->redirect(dst, sk, skb);
}
/*
* This routine is called by the ICMP module when it gets some sort of error
* condition. If err < 0 then the socket should be closed and the error
* returned to the user. If err > 0 it's just the icmp type << 8 | icmp code.
* After adjustment header points to the first 8 bytes of the tcp header. We
* need to find the appropriate port.
*
* The locking strategy used here is very "optimistic". When someone else
* accesses the socket the ICMP is just dropped and for some paths there is no
* check at all. A more general error queue to queue errors for later handling
* is probably better.
*/
static void dccp_v4_err(struct sk_buff *skb, u32 info)
{
const struct iphdr *iph = (struct iphdr *)skb->data;
const u8 offset = iph->ihl << 2;
const struct dccp_hdr *dh = (struct dccp_hdr *)(skb->data + offset);
struct dccp_sock *dp;
struct inet_sock *inet;
const int type = icmp_hdr(skb)->type;
const int code = icmp_hdr(skb)->code;
struct sock *sk;
__u64 seq;
int err;
struct net *net = dev_net(skb->dev);
if (skb->len < offset + sizeof(*dh) ||
skb->len < offset + __dccp_basic_hdr_len(dh)) {
ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
return;
}
sk = inet_lookup(net, &dccp_hashinfo,
iph->daddr, dh->dccph_dport,
iph->saddr, dh->dccph_sport, inet_iif(skb));
if (sk == NULL) {
ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
return;
}
if (sk->sk_state == DCCP_TIME_WAIT) {
inet_twsk_put(inet_twsk(sk));
return;
}
bh_lock_sock(sk);
/* If too many ICMPs get dropped on busy
* servers this needs to be solved differently.
*/
if (sock_owned_by_user(sk))
NET_INC_STATS_BH(net, LINUX_MIB_LOCKDROPPEDICMPS);
if (sk->sk_state == DCCP_CLOSED)
goto out;
dp = dccp_sk(sk);
seq = dccp_hdr_seq(dh);
if ((1 << sk->sk_state) & ~(DCCPF_REQUESTING | DCCPF_LISTEN) &&
!between48(seq, dp->dccps_awl, dp->dccps_awh)) {
NET_INC_STATS_BH(net, LINUX_MIB_OUTOFWINDOWICMPS);
goto out;
}
switch (type) {
case ICMP_REDIRECT:
dccp_do_redirect(skb, sk);
goto out;
case ICMP_SOURCE_QUENCH:
/* Just silently ignore these. */
goto out;
case ICMP_PARAMETERPROB:
err = EPROTO;
break;
case ICMP_DEST_UNREACH:
if (code > NR_ICMP_UNREACH)
goto out;
if (code == ICMP_FRAG_NEEDED) { /* PMTU discovery (RFC1191) */
if (!sock_owned_by_user(sk))
dccp_do_pmtu_discovery(sk, iph, info);
goto out;
}
err = icmp_err_convert[code].errno;
break;
case ICMP_TIME_EXCEEDED:
err = EHOSTUNREACH;
break;
default:
goto out;
}
switch (sk->sk_state) {
struct request_sock *req , **prev;
case DCCP_LISTEN:
if (sock_owned_by_user(sk))
goto out;
req = inet_csk_search_req(sk, &prev, dh->dccph_dport,
iph->daddr, iph->saddr);
if (!req)
goto out;
/*
* ICMPs are not backlogged, hence we cannot get an established
* socket here.
*/
WARN_ON(req->sk);
if (!between48(seq, dccp_rsk(req)->dreq_iss,
dccp_rsk(req)->dreq_gss)) {
NET_INC_STATS_BH(net, LINUX_MIB_OUTOFWINDOWICMPS);
goto out;
}
/*
* Still in RESPOND, just remove it silently.
* There is no good way to pass the error to the newly
* created socket, and POSIX does not want network
* errors returned from accept().
*/
inet_csk_reqsk_queue_drop(sk, req, prev);
goto out;
case DCCP_REQUESTING:
case DCCP_RESPOND:
if (!sock_owned_by_user(sk)) {
DCCP_INC_STATS_BH(DCCP_MIB_ATTEMPTFAILS);
sk->sk_err = err;
sk->sk_error_report(sk);
dccp_done(sk);
} else
sk->sk_err_soft = err;
goto out;
}
/* If we've already connected we will keep trying
* until we time out, or the user gives up.
*
* rfc1122 4.2.3.9 allows to consider as hard errors
* only PROTO_UNREACH and PORT_UNREACH (well, FRAG_FAILED too,
* but it is obsoleted by pmtu discovery).
*
* Note, that in modern internet, where routing is unreliable
* and in each dark corner broken firewalls sit, sending random
* errors ordered by their masters even this two messages finally lose
* their original sense (even Linux sends invalid PORT_UNREACHs)
*
* Now we are in compliance with RFCs.
* --ANK (980905)
*/
inet = inet_sk(sk);
if (!sock_owned_by_user(sk) && inet->recverr) {
sk->sk_err = err;
sk->sk_error_report(sk);
} else /* Only an error on timeout */
sk->sk_err_soft = err;
out:
bh_unlock_sock(sk);
sock_put(sk);
}
static inline __sum16 dccp_v4_csum_finish(struct sk_buff *skb,
__be32 src, __be32 dst)
{
return csum_tcpudp_magic(src, dst, skb->len, IPPROTO_DCCP, skb->csum);
}
void dccp_v4_send_check(struct sock *sk, struct sk_buff *skb)
{
const struct inet_sock *inet = inet_sk(sk);
struct dccp_hdr *dh = dccp_hdr(skb);
dccp_csum_outgoing(skb);
dh->dccph_checksum = dccp_v4_csum_finish(skb,
inet->inet_saddr,
inet->inet_daddr);
}
EXPORT_SYMBOL_GPL(dccp_v4_send_check);
static inline u64 dccp_v4_init_sequence(const struct sk_buff *skb)
{
return secure_dccp_sequence_number(ip_hdr(skb)->daddr,
ip_hdr(skb)->saddr,
dccp_hdr(skb)->dccph_dport,
dccp_hdr(skb)->dccph_sport);
}
/*
* The three way handshake has completed - we got a valid ACK or DATAACK -
* now create the new socket.
*
* This is the equivalent of TCP's tcp_v4_syn_recv_sock
*/
struct sock *dccp_v4_request_recv_sock(struct sock *sk, struct sk_buff *skb,
struct request_sock *req,
struct dst_entry *dst)
{
struct inet_request_sock *ireq;
struct inet_sock *newinet;
struct sock *newsk;
if (sk_acceptq_is_full(sk))
goto exit_overflow;
newsk = dccp_create_openreq_child(sk, req, skb);
if (newsk == NULL)
goto exit_nonewsk;
newinet = inet_sk(newsk);
ireq = inet_rsk(req);
newinet->inet_daddr = ireq->ir_rmt_addr;
newinet->inet_rcv_saddr = ireq->ir_loc_addr;
newinet->inet_saddr = ireq->ir_loc_addr;
newinet->inet_opt = ireq->opt;
ireq->opt = NULL;
newinet->mc_index = inet_iif(skb);
newinet->mc_ttl = ip_hdr(skb)->ttl;
newinet->inet_id = jiffies;
if (dst == NULL && (dst = inet_csk_route_child_sock(sk, newsk, req)) == NULL)
goto put_and_exit;
sk_setup_caps(newsk, dst);
dccp_sync_mss(newsk, dst_mtu(dst));
if (__inet_inherit_port(sk, newsk) < 0)
goto put_and_exit;
__inet_hash_nolisten(newsk, NULL);
return newsk;
exit_overflow:
NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS);
exit_nonewsk:
dst_release(dst);
exit:
NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENDROPS);
return NULL;
put_and_exit:
inet_csk_prepare_forced_close(newsk);
dccp_done(newsk);
goto exit;
}
EXPORT_SYMBOL_GPL(dccp_v4_request_recv_sock);
static struct sock *dccp_v4_hnd_req(struct sock *sk, struct sk_buff *skb)
{
const struct dccp_hdr *dh = dccp_hdr(skb);
const struct iphdr *iph = ip_hdr(skb);
struct sock *nsk;
struct request_sock **prev;
/* Find possible connection requests. */
struct request_sock *req = inet_csk_search_req(sk, &prev,
dh->dccph_sport,
iph->saddr, iph->daddr);
if (req != NULL)
return dccp_check_req(sk, skb, req, prev);
nsk = inet_lookup_established(sock_net(sk), &dccp_hashinfo,
iph->saddr, dh->dccph_sport,
iph->daddr, dh->dccph_dport,
inet_iif(skb));
if (nsk != NULL) {
if (nsk->sk_state != DCCP_TIME_WAIT) {
bh_lock_sock(nsk);
return nsk;
}
inet_twsk_put(inet_twsk(nsk));
return NULL;
}
return sk;
}
static struct dst_entry* dccp_v4_route_skb(struct net *net, struct sock *sk,
struct sk_buff *skb)
{
struct rtable *rt;
const struct iphdr *iph = ip_hdr(skb);
struct flowi4 fl4 = {
.flowi4_oif = inet_iif(skb),
.daddr = iph->saddr,
.saddr = iph->daddr,
.flowi4_tos = RT_CONN_FLAGS(sk),
.flowi4_proto = sk->sk_protocol,
.fl4_sport = dccp_hdr(skb)->dccph_dport,
.fl4_dport = dccp_hdr(skb)->dccph_sport,
};
security_skb_classify_flow(skb, flowi4_to_flowi(&fl4));
rt = ip_route_output_flow(net, &fl4, sk);
if (IS_ERR(rt)) {
IP_INC_STATS_BH(net, IPSTATS_MIB_OUTNOROUTES);
return NULL;
}
return &rt->dst;
}
static int dccp_v4_send_response(struct sock *sk, struct request_sock *req)
{
int err = -1;
struct sk_buff *skb;
struct dst_entry *dst;
struct flowi4 fl4;
dst = inet_csk_route_req(sk, &fl4, req);
if (dst == NULL)
goto out;
skb = dccp_make_response(sk, dst, req);
if (skb != NULL) {
const struct inet_request_sock *ireq = inet_rsk(req);
struct dccp_hdr *dh = dccp_hdr(skb);
dh->dccph_checksum = dccp_v4_csum_finish(skb, ireq->ir_loc_addr,
ireq->ir_rmt_addr);
err = ip_build_and_send_pkt(skb, sk, ireq->ir_loc_addr,
ireq->ir_rmt_addr,
ireq->opt);
err = net_xmit_eval(err);
}
out:
dst_release(dst);
return err;
}
static void dccp_v4_ctl_send_reset(struct sock *sk, struct sk_buff *rxskb)
{
int err;
const struct iphdr *rxiph;
struct sk_buff *skb;
struct dst_entry *dst;
struct net *net = dev_net(skb_dst(rxskb)->dev);
struct sock *ctl_sk = net->dccp.v4_ctl_sk;
/* Never send a reset in response to a reset. */
if (dccp_hdr(rxskb)->dccph_type == DCCP_PKT_RESET)
return;
if (skb_rtable(rxskb)->rt_type != RTN_LOCAL)
return;
dst = dccp_v4_route_skb(net, ctl_sk, rxskb);
if (dst == NULL)
return;
skb = dccp_ctl_make_reset(ctl_sk, rxskb);
if (skb == NULL)
goto out;
rxiph = ip_hdr(rxskb);
dccp_hdr(skb)->dccph_checksum = dccp_v4_csum_finish(skb, rxiph->saddr,
rxiph->daddr);
skb_dst_set(skb, dst_clone(dst));
bh_lock_sock(ctl_sk);
err = ip_build_and_send_pkt(skb, ctl_sk,
rxiph->daddr, rxiph->saddr, NULL);
bh_unlock_sock(ctl_sk);
if (net_xmit_eval(err) == 0) {
DCCP_INC_STATS_BH(DCCP_MIB_OUTSEGS);
DCCP_INC_STATS_BH(DCCP_MIB_OUTRSTS);
}
out:
dst_release(dst);
}
static void dccp_v4_reqsk_destructor(struct request_sock *req)
{
dccp_feat_list_purge(&dccp_rsk(req)->dreq_featneg);
kfree(inet_rsk(req)->opt);
}
void dccp_syn_ack_timeout(struct sock *sk, struct request_sock *req)
{
}
EXPORT_SYMBOL(dccp_syn_ack_timeout);
static struct request_sock_ops dccp_request_sock_ops __read_mostly = {
.family = PF_INET,
.obj_size = sizeof(struct dccp_request_sock),
.rtx_syn_ack = dccp_v4_send_response,
.send_ack = dccp_reqsk_send_ack,
.destructor = dccp_v4_reqsk_destructor,
.send_reset = dccp_v4_ctl_send_reset,
.syn_ack_timeout = dccp_syn_ack_timeout,
};
int dccp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
{
struct inet_request_sock *ireq;
struct request_sock *req;
struct dccp_request_sock *dreq;
const __be32 service = dccp_hdr_request(skb)->dccph_req_service;
struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
/* Never answer to DCCP_PKT_REQUESTs send to broadcast or multicast */
if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
return 0; /* discard, don't send a reset here */
if (dccp_bad_service_code(sk, service)) {
dcb->dccpd_reset_code = DCCP_RESET_CODE_BAD_SERVICE_CODE;
goto drop;
}
/*
* TW buckets are converted to open requests without
* 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;
/*
* Accept backlog is full. If we have already queued enough
* of warm entries in syn queue, drop request. It is better than
* clogging syn queue with openreqs with exponentially increasing
* timeout.
*/
if (sk_acceptq_is_full(sk) && inet_csk_reqsk_queue_young(sk) > 1)
goto drop;
req = inet_reqsk_alloc(&dccp_request_sock_ops);
if (req == NULL)
goto drop;
if (dccp_reqsk_init(req, dccp_sk(sk), skb))
goto drop_and_free;
dreq = dccp_rsk(req);
if (dccp_parse_options(sk, dreq, skb))
goto drop_and_free;
if (security_inet_conn_request(sk, skb, req))
goto drop_and_free;
ireq = inet_rsk(req);
ireq->ir_loc_addr = ip_hdr(skb)->daddr;
ireq->ir_rmt_addr = ip_hdr(skb)->saddr;
/*
* Step 3: Process LISTEN state
*
* Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie
*
* Setting S.SWL/S.SWH to is deferred to dccp_create_openreq_child().
*/
dreq->dreq_isr = dcb->dccpd_seq;
dreq->dreq_gsr = dreq->dreq_isr;
dreq->dreq_iss = dccp_v4_init_sequence(skb);
dreq->dreq_gss = dreq->dreq_iss;
dreq->dreq_service = service;
if (dccp_v4_send_response(sk, req))
goto drop_and_free;
inet_csk_reqsk_queue_hash_add(sk, req, DCCP_TIMEOUT_INIT);
return 0;
drop_and_free:
reqsk_free(req);
drop:
DCCP_INC_STATS_BH(DCCP_MIB_ATTEMPTFAILS);
return -1;
}
EXPORT_SYMBOL_GPL(dccp_v4_conn_request);
int dccp_v4_do_rcv(struct sock *sk, struct sk_buff *skb)
{
struct dccp_hdr *dh = dccp_hdr(skb);
if (sk->sk_state == DCCP_OPEN) { /* Fast path */
if (dccp_rcv_established(sk, skb, dh, skb->len))
goto reset;
return 0;
}
/*
* Step 3: Process LISTEN state
* If P.type == Request or P contains a valid Init Cookie option,
* (* Must scan the packet's options to check for Init
* Cookies. Only Init Cookies are processed here,
* however; other options are processed in Step 8. This
* scan need only be performed if the endpoint uses Init
* Cookies *)
* (* Generate a new socket and switch to that socket *)
* Set S := new socket for this port pair
* S.state = RESPOND
* Choose S.ISS (initial seqno) or set from Init Cookies
* Initialize S.GAR := S.ISS
* Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookies
* Continue with S.state == RESPOND
* (* A Response packet will be generated in Step 11 *)
* Otherwise,
* Generate Reset(No Connection) unless P.type == Reset
* Drop packet and return
*
* NOTE: the check for the packet types is done in
* dccp_rcv_state_process
*/
if (sk->sk_state == DCCP_LISTEN) {
struct sock *nsk = dccp_v4_hnd_req(sk, skb);
if (nsk == NULL)
goto discard;
if (nsk != sk) {
if (dccp_child_process(sk, nsk, skb))
goto reset;
return 0;
}
}
if (dccp_rcv_state_process(sk, skb, dh, skb->len))
goto reset;
return 0;
reset:
dccp_v4_ctl_send_reset(sk, skb);
discard:
kfree_skb(skb);
return 0;
}
EXPORT_SYMBOL_GPL(dccp_v4_do_rcv);
/**
* dccp_invalid_packet - check for malformed packets
* Implements RFC 4340, 8.5: Step 1: Check header basics
* Packets that fail these checks are ignored and do not receive Resets.
*/
int dccp_invalid_packet(struct sk_buff *skb)
{
const struct dccp_hdr *dh;
unsigned int cscov;
if (skb->pkt_type != PACKET_HOST)
return 1;
/* If the packet is shorter than 12 bytes, drop packet and return */
if (!pskb_may_pull(skb, sizeof(struct dccp_hdr))) {
DCCP_WARN("pskb_may_pull failed\n");
return 1;
}
dh = dccp_hdr(skb);
/* If P.type is not understood, drop packet and return */
if (dh->dccph_type >= DCCP_PKT_INVALID) {
DCCP_WARN("invalid packet type\n");
return 1;
}
/*
* If P.Data Offset is too small for packet type, drop packet and return
*/
if (dh->dccph_doff < dccp_hdr_len(skb) / sizeof(u32)) {
DCCP_WARN("P.Data Offset(%u) too small\n", dh->dccph_doff);
return 1;
}
/*
* If P.Data Offset is too too large for packet, drop packet and return
*/
if (!pskb_may_pull(skb, dh->dccph_doff * sizeof(u32))) {
DCCP_WARN("P.Data Offset(%u) too large\n", dh->dccph_doff);
return 1;
}
/*
* If P.type is not Data, Ack, or DataAck and P.X == 0 (the packet
* has short sequence numbers), drop packet and return
*/
if ((dh->dccph_type < DCCP_PKT_DATA ||
dh->dccph_type > DCCP_PKT_DATAACK) && dh->dccph_x == 0) {
DCCP_WARN("P.type (%s) not Data || [Data]Ack, while P.X == 0\n",
dccp_packet_name(dh->dccph_type));
return 1;
}
/*
* If P.CsCov is too large for the packet size, drop packet and return.
* This must come _before_ checksumming (not as RFC 4340 suggests).
*/
cscov = dccp_csum_coverage(skb);
if (cscov > skb->len) {
DCCP_WARN("P.CsCov %u exceeds packet length %d\n",
dh->dccph_cscov, skb->len);
return 1;
}
/* If header checksum is incorrect, drop packet and return.
* (This step is completed in the AF-dependent functions.) */
skb->csum = skb_checksum(skb, 0, cscov, 0);
return 0;
}
EXPORT_SYMBOL_GPL(dccp_invalid_packet);
/* this is called when real data arrives */
static int dccp_v4_rcv(struct sk_buff *skb)
{
const struct dccp_hdr *dh;
const struct iphdr *iph;
struct sock *sk;
int min_cov;
/* Step 1: Check header basics */
if (dccp_invalid_packet(skb))
goto discard_it;
iph = ip_hdr(skb);
/* Step 1: If header checksum is incorrect, drop packet and return */
if (dccp_v4_csum_finish(skb, iph->saddr, iph->daddr)) {
DCCP_WARN("dropped packet with invalid checksum\n");
goto discard_it;
}
dh = dccp_hdr(skb);
DCCP_SKB_CB(skb)->dccpd_seq = dccp_hdr_seq(dh);
DCCP_SKB_CB(skb)->dccpd_type = dh->dccph_type;
dccp_pr_debug("%8.8s src=%pI4@%-5d dst=%pI4@%-5d seq=%llu",
dccp_packet_name(dh->dccph_type),
&iph->saddr, ntohs(dh->dccph_sport),
&iph->daddr, ntohs(dh->dccph_dport),
(unsigned long long) DCCP_SKB_CB(skb)->dccpd_seq);
if (dccp_packet_without_ack(skb)) {
DCCP_SKB_CB(skb)->dccpd_ack_seq = DCCP_PKT_WITHOUT_ACK_SEQ;
dccp_pr_debug_cat("\n");
} else {
DCCP_SKB_CB(skb)->dccpd_ack_seq = dccp_hdr_ack_seq(skb);
dccp_pr_debug_cat(", ack=%llu\n", (unsigned long long)
DCCP_SKB_CB(skb)->dccpd_ack_seq);
}
/* Step 2:
* Look up flow ID in table and get corresponding socket */
sk = __inet_lookup_skb(&dccp_hashinfo, skb,
dh->dccph_sport, dh->dccph_dport);
/*
* Step 2:
* If no socket ...
*/
if (sk == NULL) {
dccp_pr_debug("failed to look up flow ID in table and "
"get corresponding socket\n");
goto no_dccp_socket;
}
/*
* Step 2:
* ... or S.state == TIMEWAIT,
* Generate Reset(No Connection) unless P.type == Reset
* Drop packet and return
*/
if (sk->sk_state == DCCP_TIME_WAIT) {
dccp_pr_debug("sk->sk_state == DCCP_TIME_WAIT: do_time_wait\n");
inet_twsk_put(inet_twsk(sk));
goto no_dccp_socket;
}
/*
* RFC 4340, sec. 9.2.1: Minimum Checksum Coverage
* o if MinCsCov = 0, only packets with CsCov = 0 are accepted
* o if MinCsCov > 0, also accept packets with CsCov >= MinCsCov
*/
min_cov = dccp_sk(sk)->dccps_pcrlen;
if (dh->dccph_cscov && (min_cov == 0 || dh->dccph_cscov < min_cov)) {
dccp_pr_debug("Packet CsCov %d does not satisfy MinCsCov %d\n",
dh->dccph_cscov, min_cov);
/* FIXME: "Such packets SHOULD be reported using Data Dropped
* options (Section 11.7) with Drop Code 0, Protocol
* Constraints." */
goto discard_and_relse;
}
if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
goto discard_and_relse;
nf_reset(skb);
return sk_receive_skb(sk, skb, 1);
no_dccp_socket:
if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb))
goto discard_it;
/*
* Step 2:
* If no socket ...
* Generate Reset(No Connection) unless P.type == Reset
* Drop packet and return
*/
if (dh->dccph_type != DCCP_PKT_RESET) {
DCCP_SKB_CB(skb)->dccpd_reset_code =
DCCP_RESET_CODE_NO_CONNECTION;
dccp_v4_ctl_send_reset(sk, skb);
}
discard_it:
kfree_skb(skb);
return 0;
discard_and_relse:
sock_put(sk);
goto discard_it;
}
static const struct inet_connection_sock_af_ops dccp_ipv4_af_ops = {
.queue_xmit = ip_queue_xmit,
.send_check = dccp_v4_send_check,
.rebuild_header = inet_sk_rebuild_header,
.conn_request = dccp_v4_conn_request,
.syn_recv_sock = dccp_v4_request_recv_sock,
.net_header_len = sizeof(struct iphdr),
.setsockopt = ip_setsockopt,
.getsockopt = ip_getsockopt,
.addr2sockaddr = inet_csk_addr2sockaddr,
.sockaddr_len = sizeof(struct sockaddr_in),
.bind_conflict = inet_csk_bind_conflict,
#ifdef CONFIG_COMPAT
.compat_setsockopt = compat_ip_setsockopt,
.compat_getsockopt = compat_ip_getsockopt,
#endif
};
static int dccp_v4_init_sock(struct sock *sk)
{
static __u8 dccp_v4_ctl_sock_initialized;
int err = dccp_init_sock(sk, dccp_v4_ctl_sock_initialized);
if (err == 0) {
if (unlikely(!dccp_v4_ctl_sock_initialized))
dccp_v4_ctl_sock_initialized = 1;
inet_csk(sk)->icsk_af_ops = &dccp_ipv4_af_ops;
}
return err;
}
static struct timewait_sock_ops dccp_timewait_sock_ops = {
.twsk_obj_size = sizeof(struct inet_timewait_sock),
};
static struct proto dccp_v4_prot = {
.name = "DCCP",
.owner = THIS_MODULE,
.close = dccp_close,
.connect = dccp_v4_connect,
.disconnect = dccp_disconnect,
.ioctl = dccp_ioctl,
.init = dccp_v4_init_sock,
.setsockopt = dccp_setsockopt,
.getsockopt = dccp_getsockopt,
.sendmsg = dccp_sendmsg,
.recvmsg = dccp_recvmsg,
.backlog_rcv = dccp_v4_do_rcv,
.hash = inet_hash,
.unhash = inet_unhash,
.accept = inet_csk_accept,
.get_port = inet_csk_get_port,
.shutdown = dccp_shutdown,
.destroy = dccp_destroy_sock,
.orphan_count = &dccp_orphan_count,
.max_header = MAX_DCCP_HEADER,
.obj_size = sizeof(struct dccp_sock),
.slab_flags = SLAB_DESTROY_BY_RCU,
.rsk_prot = &dccp_request_sock_ops,
.twsk_prot = &dccp_timewait_sock_ops,
.h.hashinfo = &dccp_hashinfo,
#ifdef CONFIG_COMPAT
.compat_setsockopt = compat_dccp_setsockopt,
.compat_getsockopt = compat_dccp_getsockopt,
#endif
};
static const struct net_protocol dccp_v4_protocol = {
.handler = dccp_v4_rcv,
.err_handler = dccp_v4_err,
.no_policy = 1,
.netns_ok = 1,
};
static const struct proto_ops inet_dccp_ops = {
.family = PF_INET,
.owner = THIS_MODULE,
.release = inet_release,
.bind = inet_bind,
.connect = inet_stream_connect,
.socketpair = sock_no_socketpair,
.accept = inet_accept,
.getname = inet_getname,
/* FIXME: work on tcp_poll to rename it to inet_csk_poll */
.poll = dccp_poll,
.ioctl = inet_ioctl,
/* FIXME: work on inet_listen to rename it to sock_common_listen */
.listen = inet_dccp_listen,
.shutdown = inet_shutdown,
.setsockopt = sock_common_setsockopt,
.getsockopt = sock_common_getsockopt,
.sendmsg = inet_sendmsg,
.recvmsg = sock_common_recvmsg,
.mmap = sock_no_mmap,
.sendpage = sock_no_sendpage,
#ifdef CONFIG_COMPAT
.compat_setsockopt = compat_sock_common_setsockopt,
.compat_getsockopt = compat_sock_common_getsockopt,
#endif
};
static struct inet_protosw dccp_v4_protosw = {
.type = SOCK_DCCP,
.protocol = IPPROTO_DCCP,
.prot = &dccp_v4_prot,
.ops = &inet_dccp_ops,
.no_check = 0,
.flags = INET_PROTOSW_ICSK,
};
static int __net_init dccp_v4_init_net(struct net *net)
{
if (dccp_hashinfo.bhash == NULL)
return -ESOCKTNOSUPPORT;
return inet_ctl_sock_create(&net->dccp.v4_ctl_sk, PF_INET,
SOCK_DCCP, IPPROTO_DCCP, net);
}
static void __net_exit dccp_v4_exit_net(struct net *net)
{
inet_ctl_sock_destroy(net->dccp.v4_ctl_sk);
}
static struct pernet_operations dccp_v4_ops = {
.init = dccp_v4_init_net,
.exit = dccp_v4_exit_net,
};
static int __init dccp_v4_init(void)
{
int err = proto_register(&dccp_v4_prot, 1);
if (err != 0)
goto out;
err = inet_add_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
if (err != 0)
goto out_proto_unregister;
inet_register_protosw(&dccp_v4_protosw);
err = register_pernet_subsys(&dccp_v4_ops);
if (err)
goto out_destroy_ctl_sock;
out:
return err;
out_destroy_ctl_sock:
inet_unregister_protosw(&dccp_v4_protosw);
inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
out_proto_unregister:
proto_unregister(&dccp_v4_prot);
goto out;
}
static void __exit dccp_v4_exit(void)
{
unregister_pernet_subsys(&dccp_v4_ops);
inet_unregister_protosw(&dccp_v4_protosw);
inet_del_protocol(&dccp_v4_protocol, IPPROTO_DCCP);
proto_unregister(&dccp_v4_prot);
}
module_init(dccp_v4_init);
module_exit(dccp_v4_exit);
/*
* __stringify doesn't likes enums, so use SOCK_DCCP (6) and IPPROTO_DCCP (33)
* values directly, Also cover the case where the protocol is not specified,
* i.e. net-pf-PF_INET-proto-0-type-SOCK_DCCP
*/
MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 33, 6);
MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 0, 6);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Arnaldo Carvalho de Melo <acme@mandriva.com>");
MODULE_DESCRIPTION("DCCP - Datagram Congestion Controlled Protocol");