linux/net/ipv6/inet6_connection_sock.c
Lorenzo Colitti 84f39b08d7 net: support marking accepting TCP sockets
When using mark-based routing, sockets returned from accept()
may need to be marked differently depending on the incoming
connection request.

This is the case, for example, if different socket marks identify
different networks: a listening socket may want to accept
connections from all networks, but each connection should be
marked with the network that the request came in on, so that
subsequent packets are sent on the correct network.

This patch adds a sysctl to mark TCP sockets based on the fwmark
of the incoming SYN packet. If enabled, and an unmarked socket
receives a SYN, then the SYN packet's fwmark is written to the
connection's inet_request_sock, and later written back to the
accepted socket when the connection is established.  If the
socket already has a nonzero mark, then the behaviour is the same
as it is today, i.e., the listening socket's fwmark is used.

Black-box tested using user-mode linux:

- IPv4/IPv6 SYN+ACK, FIN, etc. packets are routed based on the
  mark of the incoming SYN packet.
- The socket returned by accept() is marked with the mark of the
  incoming SYN packet.
- Tested with syncookies=1 and syncookies=2.

Signed-off-by: Lorenzo Colitti <lorenzo@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2014-05-13 18:35:09 -04:00

267 lines
7.2 KiB
C

/*
* INET An implementation of the TCP/IP protocol suite for the LINUX
* operating system. INET is implemented using the BSD Socket
* interface as the means of communication with the user level.
*
* Support for INET6 connection oriented protocols.
*
* Authors: See the TCPv6 sources
*
* 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/module.h>
#include <linux/in6.h>
#include <linux/ipv6.h>
#include <linux/jhash.h>
#include <linux/slab.h>
#include <net/addrconf.h>
#include <net/inet_connection_sock.h>
#include <net/inet_ecn.h>
#include <net/inet_hashtables.h>
#include <net/ip6_route.h>
#include <net/sock.h>
#include <net/inet6_connection_sock.h>
int inet6_csk_bind_conflict(const struct sock *sk,
const struct inet_bind_bucket *tb, bool relax)
{
const struct sock *sk2;
int reuse = sk->sk_reuse;
int reuseport = sk->sk_reuseport;
kuid_t uid = sock_i_uid((struct sock *)sk);
/* We must walk the whole port owner list in this case. -DaveM */
/*
* See comment in inet_csk_bind_conflict about sock lookup
* vs net namespaces issues.
*/
sk_for_each_bound(sk2, &tb->owners) {
if (sk != sk2 &&
(!sk->sk_bound_dev_if ||
!sk2->sk_bound_dev_if ||
sk->sk_bound_dev_if == sk2->sk_bound_dev_if)) {
if ((!reuse || !sk2->sk_reuse ||
sk2->sk_state == TCP_LISTEN) &&
(!reuseport || !sk2->sk_reuseport ||
(sk2->sk_state != TCP_TIME_WAIT &&
!uid_eq(uid,
sock_i_uid((struct sock *)sk2))))) {
if (ipv6_rcv_saddr_equal(sk, sk2))
break;
}
if (!relax && reuse && sk2->sk_reuse &&
sk2->sk_state != TCP_LISTEN &&
ipv6_rcv_saddr_equal(sk, sk2))
break;
}
}
return sk2 != NULL;
}
EXPORT_SYMBOL_GPL(inet6_csk_bind_conflict);
struct dst_entry *inet6_csk_route_req(struct sock *sk,
struct flowi6 *fl6,
const struct request_sock *req)
{
struct inet_request_sock *ireq = inet_rsk(req);
struct ipv6_pinfo *np = inet6_sk(sk);
struct in6_addr *final_p, final;
struct dst_entry *dst;
memset(fl6, 0, sizeof(*fl6));
fl6->flowi6_proto = IPPROTO_TCP;
fl6->daddr = ireq->ir_v6_rmt_addr;
final_p = fl6_update_dst(fl6, np->opt, &final);
fl6->saddr = ireq->ir_v6_loc_addr;
fl6->flowi6_oif = ireq->ir_iif;
fl6->flowi6_mark = ireq->ir_mark;
fl6->fl6_dport = ireq->ir_rmt_port;
fl6->fl6_sport = htons(ireq->ir_num);
security_req_classify_flow(req, flowi6_to_flowi(fl6));
dst = ip6_dst_lookup_flow(sk, fl6, final_p);
if (IS_ERR(dst))
return NULL;
return dst;
}
/*
* request_sock (formerly open request) hash tables.
*/
static u32 inet6_synq_hash(const struct in6_addr *raddr, const __be16 rport,
const u32 rnd, const u32 synq_hsize)
{
u32 c;
c = jhash_3words((__force u32)raddr->s6_addr32[0],
(__force u32)raddr->s6_addr32[1],
(__force u32)raddr->s6_addr32[2],
rnd);
c = jhash_2words((__force u32)raddr->s6_addr32[3],
(__force u32)rport,
c);
return c & (synq_hsize - 1);
}
struct request_sock *inet6_csk_search_req(const struct sock *sk,
struct request_sock ***prevp,
const __be16 rport,
const struct in6_addr *raddr,
const struct in6_addr *laddr,
const int iif)
{
const struct inet_connection_sock *icsk = inet_csk(sk);
struct listen_sock *lopt = icsk->icsk_accept_queue.listen_opt;
struct request_sock *req, **prev;
for (prev = &lopt->syn_table[inet6_synq_hash(raddr, rport,
lopt->hash_rnd,
lopt->nr_table_entries)];
(req = *prev) != NULL;
prev = &req->dl_next) {
const struct inet_request_sock *ireq = inet_rsk(req);
if (ireq->ir_rmt_port == rport &&
req->rsk_ops->family == AF_INET6 &&
ipv6_addr_equal(&ireq->ir_v6_rmt_addr, raddr) &&
ipv6_addr_equal(&ireq->ir_v6_loc_addr, laddr) &&
(!ireq->ir_iif || ireq->ir_iif == iif)) {
WARN_ON(req->sk != NULL);
*prevp = prev;
return req;
}
}
return NULL;
}
EXPORT_SYMBOL_GPL(inet6_csk_search_req);
void inet6_csk_reqsk_queue_hash_add(struct sock *sk,
struct request_sock *req,
const unsigned long timeout)
{
struct inet_connection_sock *icsk = inet_csk(sk);
struct listen_sock *lopt = icsk->icsk_accept_queue.listen_opt;
const u32 h = inet6_synq_hash(&inet_rsk(req)->ir_v6_rmt_addr,
inet_rsk(req)->ir_rmt_port,
lopt->hash_rnd, lopt->nr_table_entries);
reqsk_queue_hash_req(&icsk->icsk_accept_queue, h, req, timeout);
inet_csk_reqsk_queue_added(sk, timeout);
}
EXPORT_SYMBOL_GPL(inet6_csk_reqsk_queue_hash_add);
void inet6_csk_addr2sockaddr(struct sock *sk, struct sockaddr * uaddr)
{
struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *) uaddr;
sin6->sin6_family = AF_INET6;
sin6->sin6_addr = sk->sk_v6_daddr;
sin6->sin6_port = inet_sk(sk)->inet_dport;
/* We do not store received flowlabel for TCP */
sin6->sin6_flowinfo = 0;
sin6->sin6_scope_id = ipv6_iface_scope_id(&sin6->sin6_addr,
sk->sk_bound_dev_if);
}
EXPORT_SYMBOL_GPL(inet6_csk_addr2sockaddr);
static inline
void __inet6_csk_dst_store(struct sock *sk, struct dst_entry *dst,
const struct in6_addr *daddr,
const struct in6_addr *saddr)
{
__ip6_dst_store(sk, dst, daddr, saddr);
}
static inline
struct dst_entry *__inet6_csk_dst_check(struct sock *sk, u32 cookie)
{
return __sk_dst_check(sk, cookie);
}
static struct dst_entry *inet6_csk_route_socket(struct sock *sk,
struct flowi6 *fl6)
{
struct inet_sock *inet = inet_sk(sk);
struct ipv6_pinfo *np = inet6_sk(sk);
struct in6_addr *final_p, final;
struct dst_entry *dst;
memset(fl6, 0, sizeof(*fl6));
fl6->flowi6_proto = sk->sk_protocol;
fl6->daddr = sk->sk_v6_daddr;
fl6->saddr = np->saddr;
fl6->flowlabel = np->flow_label;
IP6_ECN_flow_xmit(sk, fl6->flowlabel);
fl6->flowi6_oif = sk->sk_bound_dev_if;
fl6->flowi6_mark = sk->sk_mark;
fl6->fl6_sport = inet->inet_sport;
fl6->fl6_dport = inet->inet_dport;
security_sk_classify_flow(sk, flowi6_to_flowi(fl6));
final_p = fl6_update_dst(fl6, np->opt, &final);
dst = __inet6_csk_dst_check(sk, np->dst_cookie);
if (!dst) {
dst = ip6_dst_lookup_flow(sk, fl6, final_p);
if (!IS_ERR(dst))
__inet6_csk_dst_store(sk, dst, NULL, NULL);
}
return dst;
}
int inet6_csk_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl_unused)
{
struct ipv6_pinfo *np = inet6_sk(sk);
struct flowi6 fl6;
struct dst_entry *dst;
int res;
dst = inet6_csk_route_socket(sk, &fl6);
if (IS_ERR(dst)) {
sk->sk_err_soft = -PTR_ERR(dst);
sk->sk_route_caps = 0;
kfree_skb(skb);
return PTR_ERR(dst);
}
rcu_read_lock();
skb_dst_set_noref(skb, dst);
/* Restore final destination back after routing done */
fl6.daddr = sk->sk_v6_daddr;
res = ip6_xmit(sk, skb, &fl6, np->opt, np->tclass);
rcu_read_unlock();
return res;
}
EXPORT_SYMBOL_GPL(inet6_csk_xmit);
struct dst_entry *inet6_csk_update_pmtu(struct sock *sk, u32 mtu)
{
struct flowi6 fl6;
struct dst_entry *dst = inet6_csk_route_socket(sk, &fl6);
if (IS_ERR(dst))
return NULL;
dst->ops->update_pmtu(dst, sk, NULL, mtu);
dst = inet6_csk_route_socket(sk, &fl6);
return IS_ERR(dst) ? NULL : dst;
}
EXPORT_SYMBOL_GPL(inet6_csk_update_pmtu);