* [PATCH] netfilter: nf_nat: Support fullcone NAT
@ 2020-11-06 22:01 Paul Menzel
2020-11-06 23:02 ` Florian Westphal
0 siblings, 1 reply; 2+ messages in thread
From: Paul Menzel @ 2020-11-06 22:01 UTC (permalink / raw)
To: Pablo Neira Ayuso, Jozsef Kadlecsik, Florian Westphal
Cc: netfilter-devel, coreteam, linux-kernel, Xin Liu, Guohan Lu,
Kiran Kella, Akhilesh Samineni, Paul Menzel
[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: text/plain, Size: 25810 bytes --]
From: Kiran Kella <kiran.kella@broadcom.com>
Changes done in the kernel to ensure 3-tuple uniqueness of the conntrack
entries for the fullcone nat functionality.
* Hashlist is maintained for the 3-tuple unique keys (Protocol/Source
IP/Port) for all the conntrack entries.
* When NAT table rules are created with the fullcone option, the
SNAT/POSTROUTING stage ensures the ports from the pool are picked up in
such a way that the 3-tuple is uniquely assigned.
* In the DNAT/POSTROUTING stage, the fullcone behavior is ensured by checking
and reusing the 3-tuple for the Source IP/Port in the original direction.
* When the pool is exhausted of the 3-tuple assignments, the packets are
dropped, else, they will be going out of the router they being 5-tuple
unique (which is not intended).
* Passing fullcone option using iptables is part of another PR (in
sonic-buildimage repo).
The kernel changes mentioned above are done to counter the challenges
explained in the section *3.4.2.1 Handling NAT model mismatch between
the ASIC and the Kernel* in the NAT HLD [1].
[1]: https://github.com/kirankella/SONiC/blob/nat_doc_changes/doc/nat/nat_design_spec.md
[Add to SONiC in https://github.com/Azure/sonic-linux-kernel/pull/100]
Signed-off-by: Kiran Kella <kiran.kella@broadcom.com>
[forward port to Linux v4.19, https://github.com/Azure/sonic-linux-kernel/pull/147]
Signed-off-by: Akhilesh Samineni <akhilesh.samineni@broadcom.com>
Signed-off-by: Paul Menzel <pmenzel@molgen.mpg.de>
---
Dear Linux folks,
This is taken from switch network operating system (NOS) SONiC’s Linux
repository, where the support was added in September 2019 [1], and
forwarded ported to Linux 4.19 by Akhilesh in June 2020 [2].
I am sending it upstream as a request for comments, before effort is put
into forward porting it to Linux master.
Kind regards,
Paul
[1]: https://github.com/Azure/sonic-linux-kernel/pull/100
[2]: https://github.com/Azure/sonic-linux-kernel/pull/147
include/net/netfilter/nf_conntrack.h | 3 +
include/net/netfilter/nf_nat.h | 6 +
include/net/netfilter/nf_nat_l4proto.h | 12 +-
include/uapi/linux/netfilter/nf_nat.h | 1 +
net/ipv4/netfilter/nf_nat_proto_gre.c | 8 +-
net/ipv4/netfilter/nf_nat_proto_icmp.c | 6 +-
net/ipv6/netfilter/nf_nat_proto_icmpv6.c | 5 +-
net/netfilter/nf_nat_core.c | 173 ++++++++++++++++++++---
net/netfilter/nf_nat_proto_common.c | 32 +++--
net/netfilter/nf_nat_proto_dccp.c | 6 +-
net/netfilter/nf_nat_proto_sctp.c | 6 +-
net/netfilter/nf_nat_proto_tcp.c | 6 +-
net/netfilter/nf_nat_proto_udp.c | 12 +-
net/netfilter/nf_nat_proto_unknown.c | 4 +-
14 files changed, 220 insertions(+), 60 deletions(-)
diff --git a/include/net/netfilter/nf_conntrack.h b/include/net/netfilter/nf_conntrack.h
index f45141bdbb83..64b9293a31f6 100644
--- a/include/net/netfilter/nf_conntrack.h
+++ b/include/net/netfilter/nf_conntrack.h
@@ -84,6 +84,9 @@ struct nf_conn {
#if IS_ENABLED(CONFIG_NF_NAT)
struct hlist_node nat_bysource;
#endif
+ /* To optionally ensure 3-tuple uniqueness on the translated source */
+ struct hlist_node nat_by_manip_src;
+
/* all members below initialized via memset */
u8 __nfct_init_offset[0];
diff --git a/include/net/netfilter/nf_nat.h b/include/net/netfilter/nf_nat.h
index a17eb2f8d40e..7c3cc3c7b35f 100644
--- a/include/net/netfilter/nf_nat.h
+++ b/include/net/netfilter/nf_nat.h
@@ -51,6 +51,12 @@ struct nf_conn_nat *nf_ct_nat_ext_add(struct nf_conn *ct);
int nf_nat_used_tuple(const struct nf_conntrack_tuple *tuple,
const struct nf_conn *ignored_conntrack);
+/* Is this 3-tuple already taken? (not by us)*/
+int
+nf_nat_used_3_tuple(const struct nf_conntrack_tuple *tuple,
+ const struct nf_conn *ignored_conntrack,
+ enum nf_nat_manip_type maniptype);
+
static inline struct nf_conn_nat *nfct_nat(const struct nf_conn *ct)
{
#if defined(CONFIG_NF_NAT) || defined(CONFIG_NF_NAT_MODULE)
diff --git a/include/net/netfilter/nf_nat_l4proto.h b/include/net/netfilter/nf_nat_l4proto.h
index b4d6b29bca62..fbcbb9ad9e4b 100644
--- a/include/net/netfilter/nf_nat_l4proto.h
+++ b/include/net/netfilter/nf_nat_l4proto.h
@@ -32,7 +32,7 @@ struct nf_nat_l4proto {
* possible. Per-protocol part of tuple is initialized to the
* incoming packet.
*/
- void (*unique_tuple)(const struct nf_nat_l3proto *l3proto,
+ int (*unique_tuple)(const struct nf_nat_l3proto *l3proto,
struct nf_conntrack_tuple *tuple,
const struct nf_nat_range2 *range,
enum nf_nat_manip_type maniptype,
@@ -70,11 +70,11 @@ bool nf_nat_l4proto_in_range(const struct nf_conntrack_tuple *tuple,
const union nf_conntrack_man_proto *min,
const union nf_conntrack_man_proto *max);
-void nf_nat_l4proto_unique_tuple(const struct nf_nat_l3proto *l3proto,
- struct nf_conntrack_tuple *tuple,
- const struct nf_nat_range2 *range,
- enum nf_nat_manip_type maniptype,
- const struct nf_conn *ct, u16 *rover);
+int nf_nat_l4proto_unique_tuple(const struct nf_nat_l3proto *l3proto,
+ struct nf_conntrack_tuple *tuple,
+ const struct nf_nat_range2 *range,
+ enum nf_nat_manip_type maniptype,
+ const struct nf_conn *ct, u16 *rover);
int nf_nat_l4proto_nlattr_to_range(struct nlattr *tb[],
struct nf_nat_range2 *range);
diff --git a/include/uapi/linux/netfilter/nf_nat.h b/include/uapi/linux/netfilter/nf_nat.h
index 4a95c0db14d4..1cda390e17c6 100644
--- a/include/uapi/linux/netfilter/nf_nat.h
+++ b/include/uapi/linux/netfilter/nf_nat.h
@@ -11,6 +11,7 @@
#define NF_NAT_RANGE_PERSISTENT (1 << 3)
#define NF_NAT_RANGE_PROTO_RANDOM_FULLY (1 << 4)
#define NF_NAT_RANGE_PROTO_OFFSET (1 << 5)
+#define NF_NAT_RANGE_FULLCONE (1 << 6)
#define NF_NAT_RANGE_PROTO_RANDOM_ALL \
(NF_NAT_RANGE_PROTO_RANDOM | NF_NAT_RANGE_PROTO_RANDOM_FULLY)
diff --git a/net/ipv4/netfilter/nf_nat_proto_gre.c b/net/ipv4/netfilter/nf_nat_proto_gre.c
index 00fda6331ce5..d2ca4f6003ba 100644
--- a/net/ipv4/netfilter/nf_nat_proto_gre.c
+++ b/net/ipv4/netfilter/nf_nat_proto_gre.c
@@ -38,7 +38,7 @@ MODULE_AUTHOR("Harald Welte <laforge@gnumonks.org>");
MODULE_DESCRIPTION("Netfilter NAT protocol helper module for GRE");
/* generate unique tuple ... */
-static void
+static int
gre_unique_tuple(const struct nf_nat_l3proto *l3proto,
struct nf_conntrack_tuple *tuple,
const struct nf_nat_range2 *range,
@@ -52,7 +52,7 @@ gre_unique_tuple(const struct nf_nat_l3proto *l3proto,
/* If there is no master conntrack we are not PPTP,
do not change tuples */
if (!ct->master)
- return;
+ return 0;
if (maniptype == NF_NAT_MANIP_SRC)
keyptr = &tuple->src.u.gre.key;
@@ -73,11 +73,11 @@ gre_unique_tuple(const struct nf_nat_l3proto *l3proto,
for (i = 0; ; ++key) {
*keyptr = htons(min + key % range_size);
if (++i == range_size || !nf_nat_used_tuple(tuple, ct))
- return;
+ return 1;
}
pr_debug("%p: no NAT mapping\n", ct);
- return;
+ return 0;
}
/* manipulate a GRE packet according to maniptype */
diff --git a/net/ipv4/netfilter/nf_nat_proto_icmp.c b/net/ipv4/netfilter/nf_nat_proto_icmp.c
index 6d7cf1d79baf..403783cda503 100644
--- a/net/ipv4/netfilter/nf_nat_proto_icmp.c
+++ b/net/ipv4/netfilter/nf_nat_proto_icmp.c
@@ -27,7 +27,7 @@ icmp_in_range(const struct nf_conntrack_tuple *tuple,
ntohs(tuple->src.u.icmp.id) <= ntohs(max->icmp.id);
}
-static void
+static int
icmp_unique_tuple(const struct nf_nat_l3proto *l3proto,
struct nf_conntrack_tuple *tuple,
const struct nf_nat_range2 *range,
@@ -48,9 +48,9 @@ icmp_unique_tuple(const struct nf_nat_l3proto *l3proto,
tuple->src.u.icmp.id = htons(ntohs(range->min_proto.icmp.id) +
(id % range_size));
if (++i == range_size || !nf_nat_used_tuple(tuple, ct))
- return;
+ return 1;
}
- return;
+ return 0;
}
static bool
diff --git a/net/ipv6/netfilter/nf_nat_proto_icmpv6.c b/net/ipv6/netfilter/nf_nat_proto_icmpv6.c
index d9bf42ba44fa..7ff30a023f04 100644
--- a/net/ipv6/netfilter/nf_nat_proto_icmpv6.c
+++ b/net/ipv6/netfilter/nf_nat_proto_icmpv6.c
@@ -29,7 +29,7 @@ icmpv6_in_range(const struct nf_conntrack_tuple *tuple,
ntohs(tuple->src.u.icmp.id) <= ntohs(max->icmp.id);
}
-static void
+static int
icmpv6_unique_tuple(const struct nf_nat_l3proto *l3proto,
struct nf_conntrack_tuple *tuple,
const struct nf_nat_range2 *range,
@@ -50,8 +50,9 @@ icmpv6_unique_tuple(const struct nf_nat_l3proto *l3proto,
tuple->src.u.icmp.id = htons(ntohs(range->min_proto.icmp.id) +
(id % range_size));
if (++i == range_size || !nf_nat_used_tuple(tuple, ct))
- return;
+ return 1;
}
+ return 0;
}
static bool
diff --git a/net/netfilter/nf_nat_core.c b/net/netfilter/nf_nat_core.c
index 2268b10a9dcf..1b83427a7a68 100644
--- a/net/netfilter/nf_nat_core.c
+++ b/net/netfilter/nf_nat_core.c
@@ -43,6 +43,7 @@ static const struct nf_nat_l4proto __rcu **nf_nat_l4protos[NFPROTO_NUMPROTO]
static unsigned int nat_net_id __read_mostly;
static struct hlist_head *nf_nat_bysource __read_mostly;
+static struct hlist_head *nf_nat_by_manip_src __read_mostly;
static unsigned int nf_nat_htable_size __read_mostly;
static unsigned int nf_nat_hash_rnd __read_mostly;
@@ -155,6 +156,31 @@ hash_by_src(const struct net *n, const struct nf_conntrack_tuple *tuple)
return reciprocal_scale(hash, nf_nat_htable_size);
}
+static inline unsigned int
+hash_by_dst(const struct net *n, const struct nf_conntrack_tuple *tuple)
+{
+ unsigned int hash;
+
+ get_random_once(&nf_nat_hash_rnd, sizeof(nf_nat_hash_rnd));
+
+ hash = jhash2((u32 *)&tuple->dst, sizeof(tuple->dst) / sizeof(u32),
+ tuple->dst.protonum ^ nf_nat_hash_rnd ^ net_hash_mix(n));
+
+ return reciprocal_scale(hash, nf_nat_htable_size);
+}
+
+static inline int
+same_reply_dst(const struct nf_conn *ct,
+ const struct nf_conntrack_tuple *tuple)
+{
+ const struct nf_conntrack_tuple *t;
+
+ t = &ct->tuplehash[IP_CT_DIR_REPLY].tuple;
+ return (t->dst.protonum == tuple->dst.protonum &&
+ nf_inet_addr_cmp(&t->dst.u3, &tuple->dst.u3) &&
+ t->dst.u.all == tuple->dst.u.all);
+}
+
/* Is this tuple already taken? (not by us) */
int
nf_nat_used_tuple(const struct nf_conntrack_tuple *tuple,
@@ -171,7 +197,40 @@ nf_nat_used_tuple(const struct nf_conntrack_tuple *tuple,
nf_ct_invert_tuplepr(&reply, tuple);
return nf_conntrack_tuple_taken(&reply, ignored_conntrack);
}
+
+/* Is this 3-tuple already taken? (not by us) */
+int
+nf_nat_used_3_tuple(const struct nf_conntrack_tuple *tuple,
+ const struct nf_conn *ignored_conntrack,
+ enum nf_nat_manip_type maniptype)
+{
+ const struct nf_conn *ct;
+ const struct nf_conntrack_zone *zone;
+ unsigned int h;
+ struct net *net = nf_ct_net(ignored_conntrack);
+
+ /* 3-tuple uniqueness is required for translated source only */
+ if (maniptype != NF_NAT_MANIP_SRC) {
+ return 0;
+ }
+ zone = nf_ct_zone(ignored_conntrack);
+
+ /* The tuple passed here is the inverted reply (with translated source) */
+ h = hash_by_src(net, tuple);
+ hlist_for_each_entry_rcu(ct, &nf_nat_by_manip_src[h], nat_by_manip_src) {
+ struct nf_conntrack_tuple reply;
+ nf_ct_invert_tuplepr(&reply, tuple);
+ /* Compare against the destination in the reply */
+ if (same_reply_dst(ct, &reply) &&
+ net_eq(net, nf_ct_net(ct)) &&
+ nf_ct_zone_equal(ct, zone, IP_CT_DIR_ORIGINAL)) {
+ return 1;
+ }
+ }
+ return 0;
+}
EXPORT_SYMBOL(nf_nat_used_tuple);
+EXPORT_SYMBOL(nf_nat_used_3_tuple);
/* If we source map this tuple so reply looks like reply_tuple, will
* that meet the constraints of range.
@@ -237,6 +296,36 @@ find_appropriate_src(struct net *net,
return 0;
}
+/* Only called for DST manip */
+static int
+find_appropriate_dst(struct net *net,
+ const struct nf_conntrack_zone *zone,
+ const struct nf_nat_l3proto *l3proto,
+ const struct nf_nat_l4proto *l4proto,
+ const struct nf_conntrack_tuple *tuple,
+ struct nf_conntrack_tuple *result)
+{
+ struct nf_conntrack_tuple reply;
+ unsigned int h;
+ const struct nf_conn *ct;
+
+ nf_ct_invert_tuplepr(&reply, tuple);
+ h = hash_by_src(net, &reply);
+
+ hlist_for_each_entry_rcu(ct, &nf_nat_by_manip_src[h], nat_by_manip_src) {
+ if (same_reply_dst(ct, tuple) &&
+ net_eq(net, nf_ct_net(ct)) &&
+ nf_ct_zone_equal(ct, zone, IP_CT_DIR_REPLY)) {
+ /* Copy destination part from original tuple. */
+ nf_ct_invert_tuplepr(result,
+ &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple);
+ result->src = tuple->src;
+ return 1;
+ }
+ }
+ return 0;
+}
+
/* For [FUTURE] fragmentation handling, we want the least-used
* src-ip/dst-ip/proto triple. Fairness doesn't come into it. Thus
* if the range specifies 1.2.3.4 ports 10000-10005 and 1.2.3.5 ports
@@ -314,10 +403,15 @@ find_best_ips_proto(const struct nf_conntrack_zone *zone,
/* Manipulate the tuple into the range given. For NF_INET_POST_ROUTING,
* we change the source to map into the range. For NF_INET_PRE_ROUTING
* and NF_INET_LOCAL_OUT, we change the destination to map into the
- * range. It might not be possible to get a unique tuple, but we try.
+ * range. It might not be possible to get a unique 5-tuple, but we try.
* At worst (or if we race), we will end up with a final duplicate in
- * __ip_conntrack_confirm and drop the packet. */
-static void
+ * __ip_conntrack_confirm and drop the packet.
+ * If the range is of type fullcone, if we end up with a 3-tuple
+ * duplicate, we do not wait till the packet reaches the
+ * nf_conntrack_confirm to drop the packet. Instead return the packet
+ * to be dropped at this stage.
+ */
+static int
get_unique_tuple(struct nf_conntrack_tuple *tuple,
const struct nf_conntrack_tuple *orig_tuple,
const struct nf_nat_range2 *range,
@@ -327,8 +421,11 @@ get_unique_tuple(struct nf_conntrack_tuple *tuple,
const struct nf_conntrack_zone *zone;
const struct nf_nat_l3proto *l3proto;
const struct nf_nat_l4proto *l4proto;
+ struct nf_nat_range2 nat_range;
struct net *net = nf_ct_net(ct);
+ memcpy(&nat_range, range, sizeof(struct nf_nat_range2));
+
zone = nf_ct_zone(ct);
rcu_read_lock();
@@ -345,48 +442,77 @@ get_unique_tuple(struct nf_conntrack_tuple *tuple,
* manips not an issue.
*/
if (maniptype == NF_NAT_MANIP_SRC &&
- !(range->flags & NF_NAT_RANGE_PROTO_RANDOM_ALL)) {
+ !(nat_range.flags & NF_NAT_RANGE_PROTO_RANDOM_ALL)) {
/* try the original tuple first */
- if (in_range(l3proto, l4proto, orig_tuple, range)) {
+ if (in_range(l3proto, l4proto, orig_tuple, &nat_range)) {
if (!nf_nat_used_tuple(orig_tuple, ct)) {
*tuple = *orig_tuple;
goto out;
}
} else if (find_appropriate_src(net, zone, l3proto, l4proto,
- orig_tuple, tuple, range)) {
+ orig_tuple, tuple, &nat_range)) {
pr_debug("get_unique_tuple: Found current src map\n");
if (!nf_nat_used_tuple(tuple, ct))
goto out;
}
}
+ if (maniptype == NF_NAT_MANIP_DST) {
+ if (nat_range.flags & NF_NAT_RANGE_FULLCONE) {
+ /* Destination IP range does not apply when fullcone flag is set. */
+ nat_range.min_addr.ip = nat_range.max_addr.ip = orig_tuple->dst.u3.ip;
+ nat_range.min_proto.all = nat_range.max_proto.all = 0;
+
+ /* If this dstip/proto/dst-proto-part is mapped currently
+ * as a translated source for a given tuple, use that
+ */
+ if (find_appropriate_dst(net, zone, l3proto, l4proto,
+ orig_tuple, tuple)) {
+ if (!nf_nat_used_tuple(tuple, ct)) {
+ goto out;
+ }
+ } else {
+ /* If not mapped, proceed with the original tuple */
+ *tuple = *orig_tuple;
+ goto out;
+ }
+ }
+ }
+
/* 2) Select the least-used IP/proto combination in the given range */
*tuple = *orig_tuple;
- find_best_ips_proto(zone, tuple, range, ct, maniptype);
+ find_best_ips_proto(zone, tuple, &nat_range, ct, maniptype);
/* 3) The per-protocol part of the manip is made to map into
* the range to make a unique tuple.
*/
/* Only bother mapping if it's not already in range and unique */
- if (!(range->flags & NF_NAT_RANGE_PROTO_RANDOM_ALL)) {
- if (range->flags & NF_NAT_RANGE_PROTO_SPECIFIED) {
- if (!(range->flags & NF_NAT_RANGE_PROTO_OFFSET) &&
+ if (!(nat_range.flags & NF_NAT_RANGE_PROTO_RANDOM_ALL)) {
+ if (nat_range.flags & NF_NAT_RANGE_PROTO_SPECIFIED) {
+ if (!(nat_range.flags & NF_NAT_RANGE_PROTO_OFFSET) &&
l4proto->in_range(tuple, maniptype,
- &range->min_proto,
- &range->max_proto) &&
- (range->min_proto.all == range->max_proto.all ||
- !nf_nat_used_tuple(tuple, ct)))
- goto out;
+ &(nat_range.min_proto),
+ &(nat_range.max_proto))) {
+ if (nat_range.flags & NF_NAT_RANGE_FULLCONE) {
+ if (!nf_nat_used_3_tuple(tuple, ct, maniptype))
+ goto out;
+ } else {
+ if ((nat_range.min_proto.all == nat_range.max_proto.all) ||
+ !nf_nat_used_tuple(tuple, ct))
+ goto out;
+ }
+ }
} else if (!nf_nat_used_tuple(tuple, ct)) {
goto out;
}
}
/* Last chance: get protocol to try to obtain unique tuple. */
- l4proto->unique_tuple(l3proto, tuple, range, maniptype, ct);
+ return l4proto->unique_tuple(l3proto, tuple, &nat_range, maniptype, ct);
out:
rcu_read_unlock();
+ return 1;
}
struct nf_conn_nat *nf_ct_nat_ext_add(struct nf_conn *ct)
@@ -428,7 +554,9 @@ nf_nat_setup_info(struct nf_conn *ct,
nf_ct_invert_tuplepr(&curr_tuple,
&ct->tuplehash[IP_CT_DIR_REPLY].tuple);
- get_unique_tuple(&new_tuple, &curr_tuple, range, ct, maniptype);
+ if (! get_unique_tuple(&new_tuple, &curr_tuple, range, ct, maniptype)) {
+ return NF_DROP;
+ }
if (!nf_ct_tuple_equal(&new_tuple, &curr_tuple)) {
struct nf_conntrack_tuple reply;
@@ -450,12 +578,16 @@ nf_nat_setup_info(struct nf_conn *ct,
if (maniptype == NF_NAT_MANIP_SRC) {
unsigned int srchash;
+ unsigned int manip_src_hash;
spinlock_t *lock;
+ manip_src_hash = hash_by_src(net, &new_tuple);
srchash = hash_by_src(net,
&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple);
lock = &nf_nat_locks[srchash % CONNTRACK_LOCKS];
spin_lock_bh(lock);
+ hlist_add_head_rcu(&ct->nat_by_manip_src,
+ &nf_nat_by_manip_src[manip_src_hash]);
hlist_add_head_rcu(&ct->nat_bysource,
&nf_nat_bysource[srchash]);
spin_unlock_bh(lock);
@@ -644,6 +776,7 @@ static void __nf_nat_cleanup_conntrack(struct nf_conn *ct)
h = hash_by_src(nf_ct_net(ct), &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple);
spin_lock_bh(&nf_nat_locks[h % CONNTRACK_LOCKS]);
hlist_del_rcu(&ct->nat_bysource);
+ hlist_del_rcu(&ct->nat_by_manip_src);
spin_unlock_bh(&nf_nat_locks[h % CONNTRACK_LOCKS]);
}
@@ -1055,9 +1188,14 @@ static int __init nf_nat_init(void)
if (!nf_nat_bysource)
return -ENOMEM;
+ nf_nat_by_manip_src = nf_ct_alloc_hashtable(&nf_nat_htable_size, 0);
+ if (!nf_nat_by_manip_src)
+ return -ENOMEM;
+
ret = nf_ct_extend_register(&nat_extend);
if (ret < 0) {
kvfree(nf_nat_bysource);
+ kvfree(nf_nat_by_manip_src);
pr_err("Unable to register extension\n");
return ret;
}
@@ -1096,6 +1234,7 @@ static void __exit nf_nat_cleanup(void)
kfree(nf_nat_l4protos[i]);
synchronize_net();
kvfree(nf_nat_bysource);
+ kvfree(nf_nat_by_manip_src);
unregister_pernet_subsys(&nat_net_ops);
}
diff --git a/net/netfilter/nf_nat_proto_common.c b/net/netfilter/nf_nat_proto_common.c
index 5d849d835561..6ee918302a02 100644
--- a/net/netfilter/nf_nat_proto_common.c
+++ b/net/netfilter/nf_nat_proto_common.c
@@ -34,12 +34,12 @@ bool nf_nat_l4proto_in_range(const struct nf_conntrack_tuple *tuple,
}
EXPORT_SYMBOL_GPL(nf_nat_l4proto_in_range);
-void nf_nat_l4proto_unique_tuple(const struct nf_nat_l3proto *l3proto,
- struct nf_conntrack_tuple *tuple,
- const struct nf_nat_range2 *range,
- enum nf_nat_manip_type maniptype,
- const struct nf_conn *ct,
- u16 *rover)
+int nf_nat_l4proto_unique_tuple(const struct nf_nat_l3proto *l3proto,
+ struct nf_conntrack_tuple *tuple,
+ const struct nf_nat_range2 *range,
+ enum nf_nat_manip_type maniptype,
+ const struct nf_conn *ct,
+ u16 *rover)
{
unsigned int range_size, min, max, i;
__be16 *portptr;
@@ -54,7 +54,7 @@ void nf_nat_l4proto_unique_tuple(const struct nf_nat_l3proto *l3proto,
if (!(range->flags & NF_NAT_RANGE_PROTO_SPECIFIED)) {
/* If it's dst rewrite, can't change port */
if (maniptype == NF_NAT_MANIP_DST)
- return;
+ return 0;
if (ntohs(*portptr) < 1024) {
/* Loose convention: >> 512 is credential passing */
@@ -87,17 +87,27 @@ void nf_nat_l4proto_unique_tuple(const struct nf_nat_l3proto *l3proto,
off = (ntohs(*portptr) - ntohs(range->base_proto.all));
} else {
off = *rover;
+ if ((range->flags & NF_NAT_RANGE_FULLCONE) && (maniptype == NF_NAT_MANIP_SRC)) {
+ /* Try from the next L4 port in the range */
+ off++;
+ }
}
- for (i = 0; ; ++off) {
+ for (i = 0; (i != range_size); ++i, ++off) {
*portptr = htons(min + off % range_size);
- if (++i != range_size && nf_nat_used_tuple(tuple, ct))
- continue;
+ if ((range->flags & NF_NAT_RANGE_FULLCONE) && (maniptype == NF_NAT_MANIP_SRC)) {
+ if (nf_nat_used_3_tuple(tuple, ct, maniptype))
+ continue;
+ } else {
+ if (nf_nat_used_tuple(tuple, ct))
+ continue;
+ }
if (!(range->flags & (NF_NAT_RANGE_PROTO_RANDOM_ALL|
NF_NAT_RANGE_PROTO_OFFSET)))
*rover = off;
- return;
+ return 1;
}
+ return 0;
}
EXPORT_SYMBOL_GPL(nf_nat_l4proto_unique_tuple);
diff --git a/net/netfilter/nf_nat_proto_dccp.c b/net/netfilter/nf_nat_proto_dccp.c
index 67ea0d83aa5a..68ef70bb55df 100644
--- a/net/netfilter/nf_nat_proto_dccp.c
+++ b/net/netfilter/nf_nat_proto_dccp.c
@@ -20,15 +20,15 @@
static u_int16_t dccp_port_rover;
-static void
+static int
dccp_unique_tuple(const struct nf_nat_l3proto *l3proto,
struct nf_conntrack_tuple *tuple,
const struct nf_nat_range2 *range,
enum nf_nat_manip_type maniptype,
const struct nf_conn *ct)
{
- nf_nat_l4proto_unique_tuple(l3proto, tuple, range, maniptype, ct,
- &dccp_port_rover);
+ return nf_nat_l4proto_unique_tuple(l3proto, tuple, range, maniptype, ct,
+ &dccp_port_rover);
}
static bool
diff --git a/net/netfilter/nf_nat_proto_sctp.c b/net/netfilter/nf_nat_proto_sctp.c
index 1c5d9b65fbba..a9d9070c36c8 100644
--- a/net/netfilter/nf_nat_proto_sctp.c
+++ b/net/netfilter/nf_nat_proto_sctp.c
@@ -14,15 +14,15 @@
static u_int16_t nf_sctp_port_rover;
-static void
+static int
sctp_unique_tuple(const struct nf_nat_l3proto *l3proto,
struct nf_conntrack_tuple *tuple,
const struct nf_nat_range2 *range,
enum nf_nat_manip_type maniptype,
const struct nf_conn *ct)
{
- nf_nat_l4proto_unique_tuple(l3proto, tuple, range, maniptype, ct,
- &nf_sctp_port_rover);
+ return nf_nat_l4proto_unique_tuple(l3proto, tuple, range, maniptype, ct,
+ &nf_sctp_port_rover);
}
static bool
diff --git a/net/netfilter/nf_nat_proto_tcp.c b/net/netfilter/nf_nat_proto_tcp.c
index f15fcd475f98..1b039055421f 100644
--- a/net/netfilter/nf_nat_proto_tcp.c
+++ b/net/netfilter/nf_nat_proto_tcp.c
@@ -20,15 +20,15 @@
static u16 tcp_port_rover;
-static void
+static int
tcp_unique_tuple(const struct nf_nat_l3proto *l3proto,
struct nf_conntrack_tuple *tuple,
const struct nf_nat_range2 *range,
enum nf_nat_manip_type maniptype,
const struct nf_conn *ct)
{
- nf_nat_l4proto_unique_tuple(l3proto, tuple, range, maniptype, ct,
- &tcp_port_rover);
+ return nf_nat_l4proto_unique_tuple(l3proto, tuple, range, maniptype, ct,
+ &tcp_port_rover);
}
static bool
diff --git a/net/netfilter/nf_nat_proto_udp.c b/net/netfilter/nf_nat_proto_udp.c
index 5790f70a83b2..0b26bb52aef6 100644
--- a/net/netfilter/nf_nat_proto_udp.c
+++ b/net/netfilter/nf_nat_proto_udp.c
@@ -19,15 +19,15 @@
static u16 udp_port_rover;
-static void
+static int
udp_unique_tuple(const struct nf_nat_l3proto *l3proto,
struct nf_conntrack_tuple *tuple,
const struct nf_nat_range2 *range,
enum nf_nat_manip_type maniptype,
const struct nf_conn *ct)
{
- nf_nat_l4proto_unique_tuple(l3proto, tuple, range, maniptype, ct,
- &udp_port_rover);
+ return nf_nat_l4proto_unique_tuple(l3proto, tuple, range, maniptype, ct,
+ &udp_port_rover);
}
static void
@@ -97,15 +97,15 @@ static bool udplite_manip_pkt(struct sk_buff *skb,
return true;
}
-static void
+static int
udplite_unique_tuple(const struct nf_nat_l3proto *l3proto,
struct nf_conntrack_tuple *tuple,
const struct nf_nat_range2 *range,
enum nf_nat_manip_type maniptype,
const struct nf_conn *ct)
{
- nf_nat_l4proto_unique_tuple(l3proto, tuple, range, maniptype, ct,
- &udplite_port_rover);
+ return nf_nat_l4proto_unique_tuple(l3proto, tuple, range, maniptype, ct,
+ &udplite_port_rover);
}
const struct nf_nat_l4proto nf_nat_l4proto_udplite = {
diff --git a/net/netfilter/nf_nat_proto_unknown.c b/net/netfilter/nf_nat_proto_unknown.c
index c5db3e251232..377a2938cd79 100644
--- a/net/netfilter/nf_nat_proto_unknown.c
+++ b/net/netfilter/nf_nat_proto_unknown.c
@@ -25,7 +25,7 @@ static bool unknown_in_range(const struct nf_conntrack_tuple *tuple,
return true;
}
-static void unknown_unique_tuple(const struct nf_nat_l3proto *l3proto,
+static int unknown_unique_tuple(const struct nf_nat_l3proto *l3proto,
struct nf_conntrack_tuple *tuple,
const struct nf_nat_range2 *range,
enum nf_nat_manip_type maniptype,
@@ -34,7 +34,7 @@ static void unknown_unique_tuple(const struct nf_nat_l3proto *l3proto,
/* Sorry: we can't help you; if it's not unique, we can't frob
* anything.
*/
- return;
+ return 0;
}
static bool
^ permalink raw reply related [flat|nested] 2+ messages in thread* Re: [PATCH] netfilter: nf_nat: Support fullcone NAT
2020-11-06 22:01 [PATCH] netfilter: nf_nat: Support fullcone NAT Paul Menzel
@ 2020-11-06 23:02 ` Florian Westphal
0 siblings, 0 replies; 2+ messages in thread
From: Florian Westphal @ 2020-11-06 23:02 UTC (permalink / raw)
To: Paul Menzel
Cc: Pablo Neira Ayuso, Jozsef Kadlecsik, Florian Westphal,
netfilter-devel, coreteam, linux-kernel, Xin Liu, Guohan Lu,
Kiran Kella, Akhilesh Samineni
Paul Menzel <pmenzel@molgen.mpg.de> wrote:
> From: Kiran Kella <kiran.kella@broadcom.com>
>
> Changes done in the kernel to ensure 3-tuple uniqueness of the conntrack
> entries for the fullcone nat functionality.
>
> * Hashlist is maintained for the 3-tuple unique keys (Protocol/Source
> IP/Port) for all the conntrack entries.
>
> * When NAT table rules are created with the fullcone option, the
> SNAT/POSTROUTING stage ensures the ports from the pool are picked up in
> such a way that the 3-tuple is uniquely assigned.
>
> * In the DNAT/POSTROUTING stage, the fullcone behavior is ensured by checking
> and reusing the 3-tuple for the Source IP/Port in the original direction.
>
> * When the pool is exhausted of the 3-tuple assignments, the packets are
> dropped, else, they will be going out of the router they being 5-tuple
> unique (which is not intended).
>
> * Passing fullcone option using iptables is part of another PR (in
> sonic-buildimage repo).
These are way too many changes for a single patch.
Please consider splitting this ino multiple chunks, e.g. at least
separate functional fullcone from the boilerplate changes.
> The kernel changes mentioned above are done to counter the challenges
> explained in the section *3.4.2.1 Handling NAT model mismatch between
> the ASIC and the Kernel* in the NAT HLD [1].
And please add the relevant explanations from this
> [1]: https://github.com/kirankella/SONiC/blob/nat_doc_changes/doc/nat/nat_design_spec.md
... to the commit message.
> This is taken from switch network operating system (NOS) SONiC’s Linux
> repository, where the support was added in September 2019 [1], and
> forwarded ported to Linux 4.19 by Akhilesh in June 2020 [2].
> I am sending it upstream as a request for comments, before effort
> is put into forward porting it to Linux master.
I don't see any huge problems from a technical pov.
But I don't see why this functionality is needed from a pure SW
point of view.
AFAICS SONiC uses a propritary (or at least, custom) offload mechanism
to place nat entries into HW.
Netfilter already has a forwarding offload mechanism, described in
Documentation/networking/nf_flowtable.rst , so I'm not sure it makes
sense to accept this without patches to support the needed offload
support as well.
AFAIU passing fullcone makes no sense unless using offload HW that
doesn't support the current nat port allocation scheme.
And current kernel doesn't support any such HW.
Nevertheless, some comments below.
> +/* Is this 3-tuple already taken? (not by us)*/
> +int
> +nf_nat_used_3_tuple(const struct nf_conntrack_tuple *tuple,
> + const struct nf_conn *ignored_conntrack,
> + enum nf_nat_manip_type maniptype);
> +
> */
> - void (*unique_tuple)(const struct nf_nat_l3proto *l3proto,
> + int (*unique_tuple)(const struct nf_nat_l3proto *l3proto,
> struct nf_conntrack_tuple *tuple,
> const struct nf_nat_range2 *range,
> enum nf_nat_manip_type maniptype,
The above change should be done in a separate patch, so its
in a isolated change. This will ease review of the fullcone part.
> /* generate unique tuple ... */
> -static void
> +static int
> gre_unique_tuple(const struct nf_nat_l3proto *l3proto,
> struct nf_conntrack_tuple *tuple,
> const struct nf_nat_range2 *range,
> @@ -52,7 +52,7 @@ gre_unique_tuple(const struct nf_nat_l3proto *l3proto,
> /* If there is no master conntrack we are not PPTP,
> do not change tuples */
> if (!ct->master)
> - return;
> + return 0;
>
> if (maniptype == NF_NAT_MANIP_SRC)
> keyptr = &tuple->src.u.gre.key;
> @@ -73,11 +73,11 @@ gre_unique_tuple(const struct nf_nat_l3proto *l3proto,
> for (i = 0; ; ++key) {
> *keyptr = htons(min + key % range_size);
> if (++i == range_size || !nf_nat_used_tuple(tuple, ct))
> - return;
> + return 1;
> }
I suggest you use 'bool' type for this rather than int, unless you plan
to use errno codes here in some future change.
> @@ -155,6 +156,31 @@ hash_by_src(const struct net *n, const struct nf_conntrack_tuple *tuple)
> return reciprocal_scale(hash, nf_nat_htable_size);
> }
>
> +static inline unsigned int
> +hash_by_dst(const struct net *n, const struct nf_conntrack_tuple *tuple)
please avoid inline keyword in .c files for new submissions.
> +{
> + unsigned int hash;
> +
> + get_random_once(&nf_nat_hash_rnd, sizeof(nf_nat_hash_rnd));
get_random_once can't be called from multiple places for the same random
value.
[ I did not check if thats the case since patch doesn't apply to current
nf ].
> +static inline int
> +same_reply_dst(const struct nf_conn *ct,
> + const struct nf_conntrack_tuple *tuple)
> +{
> + const struct nf_conntrack_tuple *t;
> +
> + t = &ct->tuplehash[IP_CT_DIR_REPLY].tuple;
> + return (t->dst.protonum == tuple->dst.protonum &&
> + nf_inet_addr_cmp(&t->dst.u3, &tuple->dst.u3) &&
> + t->dst.u.all == tuple->dst.u.all);
> +}
Please run patches through scripts/checkpatch.pl before submission,
we try to avoid '()' in return (...);
> +/* Only called for DST manip */
> +static int
> +find_appropriate_dst(struct net *net,
> + const struct nf_conntrack_zone *zone,
> + const struct nf_nat_l3proto *l3proto,
> + const struct nf_nat_l4proto *l4proto,
> + const struct nf_conntrack_tuple *tuple,
> + struct nf_conntrack_tuple *result)
> +{
> + struct nf_conntrack_tuple reply;
> + unsigned int h;
> + const struct nf_conn *ct;
Silly, but some maintainers prefer reverse-xmas-tree, i.e.
struct nf_conntrack_tuple reply;
const struct nf_conn *ct;
unsigned int h;
> @@ -327,8 +421,11 @@ get_unique_tuple(struct nf_conntrack_tuple *tuple,
> const struct nf_conntrack_zone *zone;
> const struct nf_nat_l3proto *l3proto;
> const struct nf_nat_l4proto *l4proto;
> + struct nf_nat_range2 nat_range;
> struct net *net = nf_ct_net(ct);
>
> + memcpy(&nat_range, range, sizeof(struct nf_nat_range2));
nat_range = *range ?
> @@ -1055,9 +1188,14 @@ static int __init nf_nat_init(void)
> if (!nf_nat_bysource)
> return -ENOMEM;
>
> + nf_nat_by_manip_src = nf_ct_alloc_hashtable(&nf_nat_htable_size, 0);
> + if (!nf_nat_by_manip_src)
> + return -ENOMEM;
This lacks error unwind for nf_nat_bysource.
^ permalink raw reply [flat|nested] 2+ messages in thread
end of thread, other threads:[~2020-11-06 23:02 UTC | newest]
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2020-11-06 22:01 [PATCH] netfilter: nf_nat: Support fullcone NAT Paul Menzel
2020-11-06 23:02 ` Florian Westphal
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