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Message-Id: <20210914233006.8710-1-Cole.Dishington@alliedtelesis.co.nz>
Date: Wed, 15 Sep 2021 11:30:06 +1200
From: Cole Dishington <Cole.Dishington@...iedtelesis.co.nz>
To: pablo@...filter.org, kadlec@...filter.org, fw@...len.de,
davem@...emloft.net, kuba@...nel.org, shuah@...nel.org
Cc: linux-kernel@...r.kernel.org, netfilter-devel@...r.kernel.org,
coreteam@...filter.org, netdev@...r.kernel.org,
Cole Dishington <Cole.Dishington@...iedtelesis.co.nz>,
Anthony Lineham <anthony.lineham@...iedtelesis.co.nz>,
Scott Parlane <scott.parlane@...iedtelesis.co.nz>,
Blair Steven <blair.steven@...iedtelesis.co.nz>
Subject: [PATCH net v3] net: netfilter: Fix port selection of FTP for NF_NAT_RANGE_PROTO_SPECIFIED
FTP port selection ignores specified port ranges (with iptables
masquerade --to-ports) when creating an expectation, based on
FTP commands PORT or PASV, for the data connection.
Co-developed-by: Anthony Lineham <anthony.lineham@...iedtelesis.co.nz>
Signed-off-by: Anthony Lineham <anthony.lineham@...iedtelesis.co.nz>
Co-developed-by: Scott Parlane <scott.parlane@...iedtelesis.co.nz>
Signed-off-by: Scott Parlane <scott.parlane@...iedtelesis.co.nz>
Co-developed-by: Blair Steven <blair.steven@...iedtelesis.co.nz>
Signed-off-by: Blair Steven <blair.steven@...iedtelesis.co.nz>
Signed-off-by: Cole Dishington <Cole.Dishington@...iedtelesis.co.nz>
---
Notes:
Thanks for your time reviewing!
Changes:
- Removed check for port == 0.
- Added nf_nat_l4proto_unique_tuple() to include/net/netfilter/nf_nat.h.
- Simplify htons/ntohs calls.
- Move away from conditional call of nf_nat_l4proto_unique_tuple() to applying full range to dst port
if ftp active with PORT/ePORT is used.
- Remove check for exp->master != NULL.
Comments:
- dir is the direction of the ftp PORT/PASV request, so exp->dir is the direction
of the data connection. In nat helper, the range should be applied on !exp->dir
source port since this is the connection from the client.
include/net/netfilter/nf_nat.h | 11 ++++++++++
net/netfilter/nf_nat_core.c | 17 +++++++++++----
net/netfilter/nf_nat_ftp.c | 38 +++++++++++++++++++++++-----------
net/netfilter/nf_nat_helper.c | 10 +++++++++
4 files changed, 60 insertions(+), 16 deletions(-)
diff --git a/include/net/netfilter/nf_nat.h b/include/net/netfilter/nf_nat.h
index 0d412dd63707..89796ed2aad3 100644
--- a/include/net/netfilter/nf_nat.h
+++ b/include/net/netfilter/nf_nat.h
@@ -27,12 +27,18 @@ union nf_conntrack_nat_help {
#endif
};
+struct nf_conn_nat_range_info {
+ union nf_conntrack_man_proto min_proto;
+ union nf_conntrack_man_proto max_proto;
+};
+
/* The structure embedded in the conntrack structure. */
struct nf_conn_nat {
union nf_conntrack_nat_help help;
#if IS_ENABLED(CONFIG_NF_NAT_MASQUERADE)
int masq_index;
#endif
+ struct nf_conn_nat_range_info range_info;
};
/* Set up the info structure to map into this range. */
@@ -40,6 +46,11 @@ unsigned int nf_nat_setup_info(struct nf_conn *ct,
const struct nf_nat_range2 *range,
enum nf_nat_manip_type maniptype);
+void nf_nat_l4proto_unique_tuple(struct nf_conntrack_tuple *tuple,
+ const struct nf_nat_range2 *range,
+ enum nf_nat_manip_type maniptype,
+ const struct nf_conn *ct);
+
extern unsigned int nf_nat_alloc_null_binding(struct nf_conn *ct,
unsigned int hooknum);
diff --git a/net/netfilter/nf_nat_core.c b/net/netfilter/nf_nat_core.c
index ea923f8cf9c4..edfd72524c38 100644
--- a/net/netfilter/nf_nat_core.c
+++ b/net/netfilter/nf_nat_core.c
@@ -397,10 +397,10 @@ find_best_ips_proto(const struct nf_conntrack_zone *zone,
*
* Per-protocol part of tuple is initialized to the incoming packet.
*/
-static void nf_nat_l4proto_unique_tuple(struct nf_conntrack_tuple *tuple,
- const struct nf_nat_range2 *range,
- enum nf_nat_manip_type maniptype,
- const struct nf_conn *ct)
+void nf_nat_l4proto_unique_tuple(struct nf_conntrack_tuple *tuple,
+ const struct nf_nat_range2 *range,
+ enum nf_nat_manip_type maniptype,
+ const struct nf_conn *ct)
{
unsigned int range_size, min, max, i, attempts;
__be16 *keyptr;
@@ -623,6 +623,15 @@ nf_nat_setup_info(struct nf_conn *ct,
&ct->tuplehash[IP_CT_DIR_REPLY].tuple);
get_unique_tuple(&new_tuple, &curr_tuple, range, ct, maniptype);
+ if (range && (range->flags & NF_NAT_RANGE_PROTO_SPECIFIED)) {
+ struct nf_conn_nat *nat = nf_ct_nat_ext_add(ct);
+
+ if (WARN_ON_ONCE(!nat))
+ return NF_DROP;
+
+ nat->range_info.min_proto = range->min_proto;
+ nat->range_info.max_proto = range->max_proto;
+ }
if (!nf_ct_tuple_equal(&new_tuple, &curr_tuple)) {
struct nf_conntrack_tuple reply;
diff --git a/net/netfilter/nf_nat_ftp.c b/net/netfilter/nf_nat_ftp.c
index aace6768a64e..f14e53e8dc04 100644
--- a/net/netfilter/nf_nat_ftp.c
+++ b/net/netfilter/nf_nat_ftp.c
@@ -72,8 +72,14 @@ static unsigned int nf_nat_ftp(struct sk_buff *skb,
u_int16_t port;
int dir = CTINFO2DIR(ctinfo);
struct nf_conn *ct = exp->master;
+ struct nf_conn_nat *nat = nfct_nat(ct);
+ struct nf_nat_range2 range = {};
char buffer[sizeof("|1||65535|") + INET6_ADDRSTRLEN];
unsigned int buflen;
+ int ret;
+
+ if (WARN_ON_ONCE(!nat))
+ return NF_DROP;
pr_debug("type %i, off %u len %u\n", type, matchoff, matchlen);
@@ -86,21 +92,29 @@ static unsigned int nf_nat_ftp(struct sk_buff *skb,
* this one. */
exp->expectfn = nf_nat_follow_master;
- /* Try to get same port: if not, try to change it. */
- for (port = ntohs(exp->saved_proto.tcp.port); port != 0; port++) {
- int ret;
+ /* Avoid applying range to external ports */
+ if (!exp->dir || !nat->range_info.min_proto.all || !nat->range_info.max_proto.all) {
+ range.min_proto.all = htons(1);
+ range.max_proto.all = htons(65535);
+ } else {
+ range.min_proto = nat->range_info.min_proto;
+ range.max_proto = nat->range_info.max_proto;
+ }
+ range.flags = NF_NAT_RANGE_PROTO_SPECIFIED;
+
+ /* Try to get same port if it matches range */
+ ret = -1;
+ port = ntohs(exp->tuple.dst.u.tcp.port);
+ if (ntohs(range.min_proto.all) <= port && port <= ntohs(range.max_proto.all))
+ ret = nf_ct_expect_related(exp, 0);
- exp->tuple.dst.u.tcp.port = htons(port);
+ /* Same port is not available, try to change it */
+ if (ret != 0) {
+ nf_nat_l4proto_unique_tuple(&exp->tuple, &range, NF_NAT_MANIP_DST, ct);
+ port = ntohs(exp->tuple.dst.u.tcp.port);
ret = nf_ct_expect_related(exp, 0);
- if (ret == 0)
- break;
- else if (ret != -EBUSY) {
- port = 0;
- break;
- }
}
-
- if (port == 0) {
+ if (ret != 0) {
nf_ct_helper_log(skb, ct, "all ports in use");
return NF_DROP;
}
diff --git a/net/netfilter/nf_nat_helper.c b/net/netfilter/nf_nat_helper.c
index a263505455fc..718fc423bc44 100644
--- a/net/netfilter/nf_nat_helper.c
+++ b/net/netfilter/nf_nat_helper.c
@@ -188,6 +188,16 @@ void nf_nat_follow_master(struct nf_conn *ct,
range.flags = NF_NAT_RANGE_MAP_IPS;
range.min_addr = range.max_addr
= ct->master->tuplehash[!exp->dir].tuple.dst.u3;
+ if (!exp->dir) {
+ struct nf_conn_nat *nat = nfct_nat(exp->master);
+
+ if (nat && nat->range_info.min_proto.all &&
+ nat->range_info.max_proto.all) {
+ range.min_proto = nat->range_info.min_proto;
+ range.max_proto = nat->range_info.max_proto;
+ range.flags |= NF_NAT_RANGE_PROTO_SPECIFIED;
+ }
+ }
nf_nat_setup_info(ct, &range, NF_NAT_MANIP_SRC);
/* For DST manip, map port here to where it's expected. */
--
2.33.0
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