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conntrack.c
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/*
* Copyright (c) 2015 Nicira, Inc.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of version 2 of the GNU General Public
* License as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*/
#include <linux/module.h>
#include <linux/openvswitch.h>
#include <linux/tcp.h>
#include <linux/udp.h>
#include <linux/sctp.h>
#include <linux/static_key.h>
#include <net/ip.h>
#include <net/genetlink.h>
#include <net/netfilter/nf_conntrack_core.h>
#include <net/netfilter/nf_conntrack_count.h>
#include <net/netfilter/nf_conntrack_helper.h>
#include <net/netfilter/nf_conntrack_labels.h>
#include <net/netfilter/nf_conntrack_seqadj.h>
#include <net/netfilter/nf_conntrack_timeout.h>
#include <net/netfilter/nf_conntrack_zones.h>
#include <net/netfilter/ipv6/nf_defrag_ipv6.h>
#include <net/ipv6_frag.h>
#if IS_ENABLED(CONFIG_NF_NAT)
#include <net/netfilter/nf_nat.h>
#endif
#include "datapath.h"
#include "conntrack.h"
#include "flow.h"
#include "flow_netlink.h"
struct ovs_ct_len_tbl {
int maxlen;
int minlen;
};
/* Metadata mark for masked write to conntrack mark */
struct md_mark {
u32 value;
u32 mask;
};
/* Metadata label for masked write to conntrack label. */
struct md_labels {
struct ovs_key_ct_labels value;
struct ovs_key_ct_labels mask;
};
enum ovs_ct_nat {
OVS_CT_NAT = 1 << 0, /* NAT for committed connections only. */
OVS_CT_SRC_NAT = 1 << 1, /* Source NAT for NEW connections. */
OVS_CT_DST_NAT = 1 << 2, /* Destination NAT for NEW connections. */
};
/* Conntrack action context for execution. */
struct ovs_conntrack_info {
struct nf_conntrack_helper *helper;
struct nf_conntrack_zone zone;
struct nf_conn *ct;
u8 commit : 1;
u8 nat : 3; /* enum ovs_ct_nat */
u8 force : 1;
u8 have_eventmask : 1;
u16 family;
u32 eventmask; /* Mask of 1 << IPCT_*. */
struct md_mark mark;
struct md_labels labels;
char timeout[CTNL_TIMEOUT_NAME_MAX];
#if IS_ENABLED(CONFIG_NF_NAT)
struct nf_nat_range2 range; /* Only present for SRC NAT and DST NAT. */
#endif
};
#if IS_ENABLED(CONFIG_NETFILTER_CONNCOUNT)
#define OVS_CT_LIMIT_UNLIMITED 0
#define OVS_CT_LIMIT_DEFAULT OVS_CT_LIMIT_UNLIMITED
#define CT_LIMIT_HASH_BUCKETS 512
static DEFINE_STATIC_KEY_FALSE(ovs_ct_limit_enabled);
struct ovs_ct_limit {
/* Elements in ovs_ct_limit_info->limits hash table */
struct hlist_node hlist_node;
struct rcu_head rcu;
u16 zone;
u32 limit;
};
struct ovs_ct_limit_info {
u32 default_limit;
struct hlist_head *limits;
struct nf_conncount_data *data;
};
static const struct nla_policy ct_limit_policy[OVS_CT_LIMIT_ATTR_MAX + 1] = {
[OVS_CT_LIMIT_ATTR_ZONE_LIMIT] = { .type = NLA_NESTED, },
};
#endif
static bool labels_nonzero(const struct ovs_key_ct_labels *labels);
static void __ovs_ct_free_action(struct ovs_conntrack_info *ct_info);
static u16 key_to_nfproto(const struct sw_flow_key *key)
{
switch (ntohs(key->eth.type)) {
case ETH_P_IP:
return NFPROTO_IPV4;
case ETH_P_IPV6:
return NFPROTO_IPV6;
default:
return NFPROTO_UNSPEC;
}
}
/* Map SKB connection state into the values used by flow definition. */
static u8 ovs_ct_get_state(enum ip_conntrack_info ctinfo)
{
u8 ct_state = OVS_CS_F_TRACKED;
switch (ctinfo) {
case IP_CT_ESTABLISHED_REPLY:
case IP_CT_RELATED_REPLY:
ct_state |= OVS_CS_F_REPLY_DIR;
break;
default:
break;
}
switch (ctinfo) {
case IP_CT_ESTABLISHED:
case IP_CT_ESTABLISHED_REPLY:
ct_state |= OVS_CS_F_ESTABLISHED;
break;
case IP_CT_RELATED:
case IP_CT_RELATED_REPLY:
ct_state |= OVS_CS_F_RELATED;
break;
case IP_CT_NEW:
ct_state |= OVS_CS_F_NEW;
break;
default:
break;
}
return ct_state;
}
static u32 ovs_ct_get_mark(const struct nf_conn *ct)
{
#if IS_ENABLED(CONFIG_NF_CONNTRACK_MARK)
return ct ? ct->mark : 0;
#else
return 0;
#endif
}
/* Guard against conntrack labels max size shrinking below 128 bits. */
#if NF_CT_LABELS_MAX_SIZE < 16
#error NF_CT_LABELS_MAX_SIZE must be at least 16 bytes
#endif
static void ovs_ct_get_labels(const struct nf_conn *ct,
struct ovs_key_ct_labels *labels)
{
struct nf_conn_labels *cl = ct ? nf_ct_labels_find(ct) : NULL;
if (cl)
memcpy(labels, cl->bits, OVS_CT_LABELS_LEN);
else
memset(labels, 0, OVS_CT_LABELS_LEN);
}
static void __ovs_ct_update_key_orig_tp(struct sw_flow_key *key,
const struct nf_conntrack_tuple *orig,
u8 icmp_proto)
{
key->ct_orig_proto = orig->dst.protonum;
if (orig->dst.protonum == icmp_proto) {
key->ct.orig_tp.src = htons(orig->dst.u.icmp.type);
key->ct.orig_tp.dst = htons(orig->dst.u.icmp.code);
} else {
key->ct.orig_tp.src = orig->src.u.all;
key->ct.orig_tp.dst = orig->dst.u.all;
}
}
static void __ovs_ct_update_key(struct sw_flow_key *key, u8 state,
const struct nf_conntrack_zone *zone,
const struct nf_conn *ct)
{
key->ct_state = state;
key->ct_zone = zone->id;
key->ct.mark = ovs_ct_get_mark(ct);
ovs_ct_get_labels(ct, &key->ct.labels);
if (ct) {
const struct nf_conntrack_tuple *orig;
/* Use the master if we have one. */
if (ct->master)
ct = ct->master;
orig = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
/* IP version must match with the master connection. */
if (key->eth.type == htons(ETH_P_IP) &&
nf_ct_l3num(ct) == NFPROTO_IPV4) {
key->ipv4.ct_orig.src = orig->src.u3.ip;
key->ipv4.ct_orig.dst = orig->dst.u3.ip;
__ovs_ct_update_key_orig_tp(key, orig, IPPROTO_ICMP);
return;
} else if (key->eth.type == htons(ETH_P_IPV6) &&
!sw_flow_key_is_nd(key) &&
nf_ct_l3num(ct) == NFPROTO_IPV6) {
key->ipv6.ct_orig.src = orig->src.u3.in6;
key->ipv6.ct_orig.dst = orig->dst.u3.in6;
__ovs_ct_update_key_orig_tp(key, orig, NEXTHDR_ICMP);
return;
}
}
/* Clear 'ct_orig_proto' to mark the non-existence of conntrack
* original direction key fields.
*/
key->ct_orig_proto = 0;
}
/* Update 'key' based on skb->_nfct. If 'post_ct' is true, then OVS has
* previously sent the packet to conntrack via the ct action. If
* 'keep_nat_flags' is true, the existing NAT flags retained, else they are
* initialized from the connection status.
*/
static void ovs_ct_update_key(const struct sk_buff *skb,
const struct ovs_conntrack_info *info,
struct sw_flow_key *key, bool post_ct,
bool keep_nat_flags)
{
const struct nf_conntrack_zone *zone = &nf_ct_zone_dflt;
enum ip_conntrack_info ctinfo;
struct nf_conn *ct;
u8 state = 0;
ct = nf_ct_get(skb, &ctinfo);
if (ct) {
state = ovs_ct_get_state(ctinfo);
/* All unconfirmed entries are NEW connections. */
if (!nf_ct_is_confirmed(ct))
state |= OVS_CS_F_NEW;
/* OVS persists the related flag for the duration of the
* connection.
*/
if (ct->master)
state |= OVS_CS_F_RELATED;
if (keep_nat_flags) {
state |= key->ct_state & OVS_CS_F_NAT_MASK;
} else {
if (ct->status & IPS_SRC_NAT)
state |= OVS_CS_F_SRC_NAT;
if (ct->status & IPS_DST_NAT)
state |= OVS_CS_F_DST_NAT;
}
zone = nf_ct_zone(ct);
} else if (post_ct) {
state = OVS_CS_F_TRACKED | OVS_CS_F_INVALID;
if (info)
zone = &info->zone;
}
__ovs_ct_update_key(key, state, zone, ct);
}
/* This is called to initialize CT key fields possibly coming in from the local
* stack.
*/
void ovs_ct_fill_key(const struct sk_buff *skb, struct sw_flow_key *key)
{
ovs_ct_update_key(skb, NULL, key, false, false);
}
#define IN6_ADDR_INITIALIZER(ADDR) \
{ (ADDR).s6_addr32[0], (ADDR).s6_addr32[1], \
(ADDR).s6_addr32[2], (ADDR).s6_addr32[3] }
int ovs_ct_put_key(const struct sw_flow_key *swkey,
const struct sw_flow_key *output, struct sk_buff *skb)
{
if (nla_put_u32(skb, OVS_KEY_ATTR_CT_STATE, output->ct_state))
return -EMSGSIZE;
if (IS_ENABLED(CONFIG_NF_CONNTRACK_ZONES) &&
nla_put_u16(skb, OVS_KEY_ATTR_CT_ZONE, output->ct_zone))
return -EMSGSIZE;
if (IS_ENABLED(CONFIG_NF_CONNTRACK_MARK) &&
nla_put_u32(skb, OVS_KEY_ATTR_CT_MARK, output->ct.mark))
return -EMSGSIZE;
if (IS_ENABLED(CONFIG_NF_CONNTRACK_LABELS) &&
nla_put(skb, OVS_KEY_ATTR_CT_LABELS, sizeof(output->ct.labels),
&output->ct.labels))
return -EMSGSIZE;
if (swkey->ct_orig_proto) {
if (swkey->eth.type == htons(ETH_P_IP)) {
struct ovs_key_ct_tuple_ipv4 orig = {
output->ipv4.ct_orig.src,
output->ipv4.ct_orig.dst,
output->ct.orig_tp.src,
output->ct.orig_tp.dst,
output->ct_orig_proto,
};
if (nla_put(skb, OVS_KEY_ATTR_CT_ORIG_TUPLE_IPV4,
sizeof(orig), &orig))
return -EMSGSIZE;
} else if (swkey->eth.type == htons(ETH_P_IPV6)) {
struct ovs_key_ct_tuple_ipv6 orig = {
IN6_ADDR_INITIALIZER(output->ipv6.ct_orig.src),
IN6_ADDR_INITIALIZER(output->ipv6.ct_orig.dst),
output->ct.orig_tp.src,
output->ct.orig_tp.dst,
output->ct_orig_proto,
};
if (nla_put(skb, OVS_KEY_ATTR_CT_ORIG_TUPLE_IPV6,
sizeof(orig), &orig))
return -EMSGSIZE;
}
}
return 0;
}
static int ovs_ct_set_mark(struct nf_conn *ct, struct sw_flow_key *key,
u32 ct_mark, u32 mask)
{
#if IS_ENABLED(CONFIG_NF_CONNTRACK_MARK)
u32 new_mark;
new_mark = ct_mark | (ct->mark & ~(mask));
if (ct->mark != new_mark) {
ct->mark = new_mark;
if (nf_ct_is_confirmed(ct))
nf_conntrack_event_cache(IPCT_MARK, ct);
key->ct.mark = new_mark;
}
return 0;
#else
return -ENOTSUPP;
#endif
}
static struct nf_conn_labels *ovs_ct_get_conn_labels(struct nf_conn *ct)
{
struct nf_conn_labels *cl;
cl = nf_ct_labels_find(ct);
if (!cl) {
nf_ct_labels_ext_add(ct);
cl = nf_ct_labels_find(ct);
}
return cl;
}
/* Initialize labels for a new, yet to be committed conntrack entry. Note that
* since the new connection is not yet confirmed, and thus no-one else has
* access to it's labels, we simply write them over.
*/
static int ovs_ct_init_labels(struct nf_conn *ct, struct sw_flow_key *key,
const struct ovs_key_ct_labels *labels,
const struct ovs_key_ct_labels *mask)
{
struct nf_conn_labels *cl, *master_cl;
bool have_mask = labels_nonzero(mask);
/* Inherit master's labels to the related connection? */
master_cl = ct->master ? nf_ct_labels_find(ct->master) : NULL;
if (!master_cl && !have_mask)
return 0; /* Nothing to do. */
cl = ovs_ct_get_conn_labels(ct);
if (!cl)
return -ENOSPC;
/* Inherit the master's labels, if any. */
if (master_cl)
*cl = *master_cl;
if (have_mask) {
u32 *dst = (u32 *)cl->bits;
int i;
for (i = 0; i < OVS_CT_LABELS_LEN_32; i++)
dst[i] = (dst[i] & ~mask->ct_labels_32[i]) |
(labels->ct_labels_32[i]
& mask->ct_labels_32[i]);
}
/* Labels are included in the IPCTNL_MSG_CT_NEW event only if the
* IPCT_LABEL bit is set in the event cache.
*/
nf_conntrack_event_cache(IPCT_LABEL, ct);
memcpy(&key->ct.labels, cl->bits, OVS_CT_LABELS_LEN);
return 0;
}
static int ovs_ct_set_labels(struct nf_conn *ct, struct sw_flow_key *key,
const struct ovs_key_ct_labels *labels,
const struct ovs_key_ct_labels *mask)
{
struct nf_conn_labels *cl;
int err;
cl = ovs_ct_get_conn_labels(ct);
if (!cl)
return -ENOSPC;
err = nf_connlabels_replace(ct, labels->ct_labels_32,
mask->ct_labels_32,
OVS_CT_LABELS_LEN_32);
if (err)
return err;
memcpy(&key->ct.labels, cl->bits, OVS_CT_LABELS_LEN);
return 0;
}
/* 'skb' should already be pulled to nh_ofs. */
static int ovs_ct_helper(struct sk_buff *skb, u16 proto)
{
const struct nf_conntrack_helper *helper;
const struct nf_conn_help *help;
enum ip_conntrack_info ctinfo;
unsigned int protoff;
struct nf_conn *ct;
int err;
ct = nf_ct_get(skb, &ctinfo);
if (!ct || ctinfo == IP_CT_RELATED_REPLY)
return NF_ACCEPT;
help = nfct_help(ct);
if (!help)
return NF_ACCEPT;
helper = rcu_dereference(help->helper);
if (!helper)
return NF_ACCEPT;
switch (proto) {
case NFPROTO_IPV4:
protoff = ip_hdrlen(skb);
break;
case NFPROTO_IPV6: {
u8 nexthdr = ipv6_hdr(skb)->nexthdr;
__be16 frag_off;
int ofs;
ofs = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr), &nexthdr,
&frag_off);
if (ofs < 0 || (frag_off & htons(~0x7)) != 0) {
pr_debug("proto header not found\n");
return NF_ACCEPT;
}
protoff = ofs;
break;
}
default:
WARN_ONCE(1, "helper invoked on non-IP family!");
return NF_DROP;
}
err = helper->help(skb, protoff, ct, ctinfo);
if (err != NF_ACCEPT)
return err;
/* Adjust seqs after helper. This is needed due to some helpers (e.g.,
* FTP with NAT) adusting the TCP payload size when mangling IP
* addresses and/or port numbers in the text-based control connection.
*/
if (test_bit(IPS_SEQ_ADJUST_BIT, &ct->status) &&
!nf_ct_seq_adjust(skb, ct, ctinfo, protoff))
return NF_DROP;
return NF_ACCEPT;
}
/* Returns 0 on success, -EINPROGRESS if 'skb' is stolen, or other nonzero
* value if 'skb' is freed.
*/
static int handle_fragments(struct net *net, struct sw_flow_key *key,
u16 zone, struct sk_buff *skb)
{
struct ovs_skb_cb ovs_cb = *OVS_CB(skb);
int err;
if (key->eth.type == htons(ETH_P_IP)) {
enum ip_defrag_users user = IP_DEFRAG_CONNTRACK_IN + zone;
memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));
err = ip_defrag(net, skb, user);
if (err)
return err;
ovs_cb.mru = IPCB(skb)->frag_max_size;
#if IS_ENABLED(CONFIG_NF_DEFRAG_IPV6)
} else if (key->eth.type == htons(ETH_P_IPV6)) {
enum ip6_defrag_users user = IP6_DEFRAG_CONNTRACK_IN + zone;
memset(IP6CB(skb), 0, sizeof(struct inet6_skb_parm));
err = nf_ct_frag6_gather(net, skb, user);
if (err) {
if (err != -EINPROGRESS)
kfree_skb(skb);
return err;
}
key->ip.proto = ipv6_hdr(skb)->nexthdr;
ovs_cb.mru = IP6CB(skb)->frag_max_size;
#endif
} else {
kfree_skb(skb);
return -EPFNOSUPPORT;
}
key->ip.frag = OVS_FRAG_TYPE_NONE;
skb_clear_hash(skb);
skb->ignore_df = 1;
*OVS_CB(skb) = ovs_cb;
return 0;
}
static struct nf_conntrack_expect *
ovs_ct_expect_find(struct net *net, const struct nf_conntrack_zone *zone,
u16 proto, const struct sk_buff *skb)
{
struct nf_conntrack_tuple tuple;
struct nf_conntrack_expect *exp;
if (!nf_ct_get_tuplepr(skb, skb_network_offset(skb), proto, net, &tuple))
return NULL;
exp = __nf_ct_expect_find(net, zone, &tuple);
if (exp) {
struct nf_conntrack_tuple_hash *h;
/* Delete existing conntrack entry, if it clashes with the
* expectation. This can happen since conntrack ALGs do not
* check for clashes between (new) expectations and existing
* conntrack entries. nf_conntrack_in() will check the
* expectations only if a conntrack entry can not be found,
* which can lead to OVS finding the expectation (here) in the
* init direction, but which will not be removed by the
* nf_conntrack_in() call, if a matching conntrack entry is
* found instead. In this case all init direction packets
* would be reported as new related packets, while reply
* direction packets would be reported as un-related
* established packets.
*/
h = nf_conntrack_find_get(net, zone, &tuple);
if (h) {
struct nf_conn *ct = nf_ct_tuplehash_to_ctrack(h);
nf_ct_delete(ct, 0, 0);
nf_conntrack_put(&ct->ct_general);
}
}
return exp;
}
/* This replicates logic from nf_conntrack_core.c that is not exported. */
static enum ip_conntrack_info
ovs_ct_get_info(const struct nf_conntrack_tuple_hash *h)
{
const struct nf_conn *ct = nf_ct_tuplehash_to_ctrack(h);
if (NF_CT_DIRECTION(h) == IP_CT_DIR_REPLY)
return IP_CT_ESTABLISHED_REPLY;
/* Once we've had two way comms, always ESTABLISHED. */
if (test_bit(IPS_SEEN_REPLY_BIT, &ct->status))
return IP_CT_ESTABLISHED;
if (test_bit(IPS_EXPECTED_BIT, &ct->status))
return IP_CT_RELATED;
return IP_CT_NEW;
}
/* Find an existing connection which this packet belongs to without
* re-attributing statistics or modifying the connection state. This allows an
* skb->_nfct lost due to an upcall to be recovered during actions execution.
*
* Must be called with rcu_read_lock.
*
* On success, populates skb->_nfct and returns the connection. Returns NULL
* if there is no existing entry.
*/
static struct nf_conn *
ovs_ct_find_existing(struct net *net, const struct nf_conntrack_zone *zone,
u8 l3num, struct sk_buff *skb, bool natted)
{
struct nf_conntrack_tuple tuple;
struct nf_conntrack_tuple_hash *h;
struct nf_conn *ct;
if (!nf_ct_get_tuplepr(skb, skb_network_offset(skb), l3num,
net, &tuple)) {
pr_debug("ovs_ct_find_existing: Can't get tuple\n");
return NULL;
}
/* Must invert the tuple if skb has been transformed by NAT. */
if (natted) {
struct nf_conntrack_tuple inverse;
if (!nf_ct_invert_tuple(&inverse, &tuple)) {
pr_debug("ovs_ct_find_existing: Inversion failed!\n");
return NULL;
}
tuple = inverse;
}
/* look for tuple match */
h = nf_conntrack_find_get(net, zone, &tuple);
if (!h)
return NULL; /* Not found. */
ct = nf_ct_tuplehash_to_ctrack(h);
/* Inverted packet tuple matches the reverse direction conntrack tuple,
* select the other tuplehash to get the right 'ctinfo' bits for this
* packet.
*/
if (natted)
h = &ct->tuplehash[!h->tuple.dst.dir];
nf_ct_set(skb, ct, ovs_ct_get_info(h));
return ct;
}
static
struct nf_conn *ovs_ct_executed(struct net *net,
const struct sw_flow_key *key,
const struct ovs_conntrack_info *info,
struct sk_buff *skb,
bool *ct_executed)
{
struct nf_conn *ct = NULL;
/* If no ct, check if we have evidence that an existing conntrack entry
* might be found for this skb. This happens when we lose a skb->_nfct
* due to an upcall, or if the direction is being forced. If the
* connection was not confirmed, it is not cached and needs to be run
* through conntrack again.
*/
*ct_executed = (key->ct_state & OVS_CS_F_TRACKED) &&
!(key->ct_state & OVS_CS_F_INVALID) &&
(key->ct_zone == info->zone.id);
if (*ct_executed || (!key->ct_state && info->force)) {
ct = ovs_ct_find_existing(net, &info->zone, info->family, skb,
!!(key->ct_state &
OVS_CS_F_NAT_MASK));
}
return ct;
}
/* Determine whether skb->_nfct is equal to the result of conntrack lookup. */
static bool skb_nfct_cached(struct net *net,
const struct sw_flow_key *key,
const struct ovs_conntrack_info *info,
struct sk_buff *skb)
{
enum ip_conntrack_info ctinfo;
struct nf_conn *ct;
bool ct_executed = true;
ct = nf_ct_get(skb, &ctinfo);
if (!ct)
ct = ovs_ct_executed(net, key, info, skb, &ct_executed);
if (ct)
nf_ct_get(skb, &ctinfo);
else
return false;
if (!net_eq(net, read_pnet(&ct->ct_net)))
return false;
if (!nf_ct_zone_equal_any(info->ct, nf_ct_zone(ct)))
return false;
if (info->helper) {
struct nf_conn_help *help;
help = nf_ct_ext_find(ct, NF_CT_EXT_HELPER);
if (help && rcu_access_pointer(help->helper) != info->helper)
return false;
}
/* Force conntrack entry direction to the current packet? */
if (info->force && CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL) {
/* Delete the conntrack entry if confirmed, else just release
* the reference.
*/
if (nf_ct_is_confirmed(ct))
nf_ct_delete(ct, 0, 0);
nf_conntrack_put(&ct->ct_general);
nf_ct_set(skb, NULL, 0);
return false;
}
return ct_executed;
}
#if IS_ENABLED(CONFIG_NF_NAT)
/* Modelled after nf_nat_ipv[46]_fn().
* range is only used for new, uninitialized NAT state.
* Returns either NF_ACCEPT or NF_DROP.
*/
static int ovs_ct_nat_execute(struct sk_buff *skb, struct nf_conn *ct,
enum ip_conntrack_info ctinfo,
const struct nf_nat_range2 *range,
enum nf_nat_manip_type maniptype)
{
int hooknum, nh_off, err = NF_ACCEPT;
nh_off = skb_network_offset(skb);
skb_pull_rcsum(skb, nh_off);
/* See HOOK2MANIP(). */
if (maniptype == NF_NAT_MANIP_SRC)
hooknum = NF_INET_LOCAL_IN; /* Source NAT */
else
hooknum = NF_INET_LOCAL_OUT; /* Destination NAT */
switch (ctinfo) {
case IP_CT_RELATED:
case IP_CT_RELATED_REPLY:
if (IS_ENABLED(CONFIG_NF_NAT) &&
skb->protocol == htons(ETH_P_IP) &&
ip_hdr(skb)->protocol == IPPROTO_ICMP) {
if (!nf_nat_icmp_reply_translation(skb, ct, ctinfo,
hooknum))
err = NF_DROP;
goto push;
} else if (IS_ENABLED(CONFIG_IPV6) &&
skb->protocol == htons(ETH_P_IPV6)) {
__be16 frag_off;
u8 nexthdr = ipv6_hdr(skb)->nexthdr;
int hdrlen = ipv6_skip_exthdr(skb,
sizeof(struct ipv6hdr),
&nexthdr, &frag_off);
if (hdrlen >= 0 && nexthdr == IPPROTO_ICMPV6) {
if (!nf_nat_icmpv6_reply_translation(skb, ct,
ctinfo,
hooknum,
hdrlen))
err = NF_DROP;
goto push;
}
}
/* Non-ICMP, fall thru to initialize if needed. */
/* fall through */
case IP_CT_NEW:
/* Seen it before? This can happen for loopback, retrans,
* or local packets.
*/
if (!nf_nat_initialized(ct, maniptype)) {
/* Initialize according to the NAT action. */
err = (range && range->flags & NF_NAT_RANGE_MAP_IPS)
/* Action is set up to establish a new
* mapping.
*/
? nf_nat_setup_info(ct, range, maniptype)
: nf_nat_alloc_null_binding(ct, hooknum);
if (err != NF_ACCEPT)
goto push;
}
break;
case IP_CT_ESTABLISHED:
case IP_CT_ESTABLISHED_REPLY:
break;
default:
err = NF_DROP;
goto push;
}
err = nf_nat_packet(ct, ctinfo, hooknum, skb);
push:
skb_push(skb, nh_off);
skb_postpush_rcsum(skb, skb->data, nh_off);
return err;
}
static void ovs_nat_update_key(struct sw_flow_key *key,
const struct sk_buff *skb,
enum nf_nat_manip_type maniptype)
{
if (maniptype == NF_NAT_MANIP_SRC) {
__be16 src;
key->ct_state |= OVS_CS_F_SRC_NAT;
if (key->eth.type == htons(ETH_P_IP))
key->ipv4.addr.src = ip_hdr(skb)->saddr;
else if (key->eth.type == htons(ETH_P_IPV6))
memcpy(&key->ipv6.addr.src, &ipv6_hdr(skb)->saddr,
sizeof(key->ipv6.addr.src));
else
return;
if (key->ip.proto == IPPROTO_UDP)
src = udp_hdr(skb)->source;
else if (key->ip.proto == IPPROTO_TCP)
src = tcp_hdr(skb)->source;
else if (key->ip.proto == IPPROTO_SCTP)
src = sctp_hdr(skb)->source;
else
return;
key->tp.src = src;
} else {
__be16 dst;
key->ct_state |= OVS_CS_F_DST_NAT;
if (key->eth.type == htons(ETH_P_IP))
key->ipv4.addr.dst = ip_hdr(skb)->daddr;
else if (key->eth.type == htons(ETH_P_IPV6))
memcpy(&key->ipv6.addr.dst, &ipv6_hdr(skb)->daddr,
sizeof(key->ipv6.addr.dst));
else
return;
if (key->ip.proto == IPPROTO_UDP)
dst = udp_hdr(skb)->dest;
else if (key->ip.proto == IPPROTO_TCP)
dst = tcp_hdr(skb)->dest;
else if (key->ip.proto == IPPROTO_SCTP)
dst = sctp_hdr(skb)->dest;
else
return;
key->tp.dst = dst;
}
}
/* Returns NF_DROP if the packet should be dropped, NF_ACCEPT otherwise. */
static int ovs_ct_nat(struct net *net, struct sw_flow_key *key,
const struct ovs_conntrack_info *info,
struct sk_buff *skb, struct nf_conn *ct,
enum ip_conntrack_info ctinfo)
{
enum nf_nat_manip_type maniptype;
int err;
/* Add NAT extension if not confirmed yet. */
if (!nf_ct_is_confirmed(ct) && !nf_ct_nat_ext_add(ct))
return NF_ACCEPT; /* Can't NAT. */
/* Determine NAT type.
* Check if the NAT type can be deduced from the tracked connection.
* Make sure new expected connections (IP_CT_RELATED) are NATted only
* when committing.
*/
if (info->nat & OVS_CT_NAT && ctinfo != IP_CT_NEW &&
ct->status & IPS_NAT_MASK &&
(ctinfo != IP_CT_RELATED || info->commit)) {
/* NAT an established or related connection like before. */
if (CTINFO2DIR(ctinfo) == IP_CT_DIR_REPLY)
/* This is the REPLY direction for a connection
* for which NAT was applied in the forward
* direction. Do the reverse NAT.
*/
maniptype = ct->status & IPS_SRC_NAT
? NF_NAT_MANIP_DST : NF_NAT_MANIP_SRC;
else
maniptype = ct->status & IPS_SRC_NAT
? NF_NAT_MANIP_SRC : NF_NAT_MANIP_DST;
} else if (info->nat & OVS_CT_SRC_NAT) {
maniptype = NF_NAT_MANIP_SRC;
} else if (info->nat & OVS_CT_DST_NAT) {
maniptype = NF_NAT_MANIP_DST;
} else {
return NF_ACCEPT; /* Connection is not NATed. */
}
err = ovs_ct_nat_execute(skb, ct, ctinfo, &info->range, maniptype);
/* Mark NAT done if successful and update the flow key. */
if (err == NF_ACCEPT)
ovs_nat_update_key(key, skb, maniptype);
return err;
}
#else /* !CONFIG_NF_NAT */
static int ovs_ct_nat(struct net *net, struct sw_flow_key *key,
const struct ovs_conntrack_info *info,
struct sk_buff *skb, struct nf_conn *ct,
enum ip_conntrack_info ctinfo)
{
return NF_ACCEPT;
}
#endif
/* Pass 'skb' through conntrack in 'net', using zone configured in 'info', if
* not done already. Update key with new CT state after passing the packet
* through conntrack.
* Note that if the packet is deemed invalid by conntrack, skb->_nfct will be
* set to NULL and 0 will be returned.
*/
static int __ovs_ct_lookup(struct net *net, struct sw_flow_key *key,
const struct ovs_conntrack_info *info,
struct sk_buff *skb)
{
/* If we are recirculating packets to match on conntrack fields and
* committing with a separate conntrack action, then we don't need to
* actually run the packet through conntrack twice unless it's for a
* different zone.
*/
bool cached = skb_nfct_cached(net, key, info, skb);
enum ip_conntrack_info ctinfo;
struct nf_conn *ct;
if (!cached) {
struct nf_hook_state state = {
.hook = NF_INET_PRE_ROUTING,
.pf = info->family,
.net = net,
};
struct nf_conn *tmpl = info->ct;
int err;
/* Associate skb with specified zone. */
if (tmpl) {
if (skb_nfct(skb))
nf_conntrack_put(skb_nfct(skb));
nf_conntrack_get(&tmpl->ct_general);
nf_ct_set(skb, tmpl, IP_CT_NEW);
}
err = nf_conntrack_in(skb, &state);
if (err != NF_ACCEPT)
return -ENOENT;
/* Clear CT state NAT flags to mark that we have not yet done
* NAT after the nf_conntrack_in() call. We can actually clear
* the whole state, as it will be re-initialized below.
*/
key->ct_state = 0;
/* Update the key, but keep the NAT flags. */
ovs_ct_update_key(skb, info, key, true, true);
}
ct = nf_ct_get(skb, &ctinfo);
if (ct) {
/* Packets starting a new connection must be NATted before the
* helper, so that the helper knows about the NAT. We enforce
* this by delaying both NAT and helper calls for unconfirmed
* connections until the committing CT action. For later
* packets NAT and Helper may be called in either order.
*
* NAT will be done only if the CT action has NAT, and only
* once per packet (per zone), as guarded by the NAT bits in
* the key->ct_state.
*/
if (info->nat && !(key->ct_state & OVS_CS_F_NAT_MASK) &&
(nf_ct_is_confirmed(ct) || info->commit) &&
ovs_ct_nat(net, key, info, skb, ct, ctinfo) != NF_ACCEPT) {
return -EINVAL;
}
/* Userspace may decide to perform a ct lookup without a helper
* specified followed by a (recirculate and) commit with one.
* Therefore, for unconfirmed connections which we will commit,
* we need to attach the helper here.
*/
if (!nf_ct_is_confirmed(ct) && info->commit &&
info->helper && !nfct_help(ct)) {
int err = __nf_ct_try_assign_helper(ct, info->ct,
GFP_ATOMIC);
if (err)
return err;
/* helper installed, add seqadj if NAT is required */
if (info->nat && !nfct_seqadj(ct)) {
if (!nfct_seqadj_ext_add(ct))
return -EINVAL;
}