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Merge git://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf

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Pablo Neira Ayuso says:

====================
Netfilter fixes for net

The following patchset contains Netfilter fixes for net coming late
in the 5.17-rc process:

1) Revert port remap to mitigate shadowing service ports, this is causing
   problems in existing setups and this mitigation can be achieved with
   explicit ruleset, eg.

	... tcp sport < 16386 tcp dport >= 32768 masquerade random

  This patches provided a built-in policy similar to the one described above.

2) Disable register tracking infrastructure in nf_tables. Florian reported
   two issues:

   - Existing expressions with no implemented .reduce interface
     that causes data-store on register should cancel the tracking.
   - Register clobbering might be possible storing data on registers that
     are larger than 32-bits.

   This might lead to generating incorrect ruleset bytecode. These two
   issues are scheduled to be addressed in the next release cycle.

* git://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf:
  netfilter: nf_tables: disable register tracking
  Revert "netfilter: conntrack: tag conntracks picked up in local out hook"
  Revert "netfilter: nat: force port remap to prevent shadowing well-known ports"
====================

Link: https://lore.kernel.org/r/20220312220315.64531-1-pablo@netfilter.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Jakub Kicinski 2022-03-14 15:51:10 -07:00
commit 15d703921f
5 changed files with 12 additions and 49 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
include/net/netfilter/nf_conntrack.h
View File

@ -97,7 +97,6 @@ struct nf_conn {
unsigned long status;
u16 cpu;
u16 local_origin:1;
possible_net_t ct_net;
#if IS_ENABLED(CONFIG_NF_NAT)

3
net/netfilter/nf_conntrack_core.c
View File

@ -1748,9 +1748,6 @@ resolve_normal_ct(struct nf_conn *tmpl,
return 0;
if (IS_ERR(h))
return PTR_ERR(h);
ct = nf_ct_tuplehash_to_ctrack(h);
ct->local_origin = state->hook == NF_INET_LOCAL_OUT;
}
ct = nf_ct_tuplehash_to_ctrack(h);

43
net/netfilter/nf_nat_core.c
View File

@ -494,38 +494,6 @@ another_round:
goto another_round;
}
static bool tuple_force_port_remap(const struct nf_conntrack_tuple *tuple)
{
u16 sp, dp;
switch (tuple->dst.protonum) {
case IPPROTO_TCP:
sp = ntohs(tuple->src.u.tcp.port);
dp = ntohs(tuple->dst.u.tcp.port);
break;
case IPPROTO_UDP:
case IPPROTO_UDPLITE:
sp = ntohs(tuple->src.u.udp.port);
dp = ntohs(tuple->dst.u.udp.port);
break;
default:
return false;
}
/* IANA: System port range: 1-1023,
* user port range: 1024-49151,
* private port range: 49152-65535.
*
* Linux default ephemeral port range is 32768-60999.
*
* Enforce port remapping if sport is significantly lower
* than dport to prevent NAT port shadowing, i.e.
* accidental match of 'new' inbound connection vs.
* existing outbound one.
*/
return sp < 16384 && dp >= 32768;
}
/* 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
@ -539,17 +507,11 @@ get_unique_tuple(struct nf_conntrack_tuple *tuple,
struct nf_conn *ct,
enum nf_nat_manip_type maniptype)
{
bool random_port = range->flags & NF_NAT_RANGE_PROTO_RANDOM_ALL;
const struct nf_conntrack_zone *zone;
struct net *net = nf_ct_net(ct);
zone = nf_ct_zone(ct);
if (maniptype == NF_NAT_MANIP_SRC &&
!random_port &&
!ct->local_origin)
random_port = tuple_force_port_remap(orig_tuple);
/* 1) If this srcip/proto/src-proto-part is currently mapped,
* and that same mapping gives a unique tuple within the given
* range, use that.
@ -558,7 +520,8 @@ get_unique_tuple(struct nf_conntrack_tuple *tuple,
* So far, we don't do local source mappings, so multiple
* manips not an issue.
*/
if (maniptype == NF_NAT_MANIP_SRC && !random_port) {
if (maniptype == NF_NAT_MANIP_SRC &&
!(range->flags & NF_NAT_RANGE_PROTO_RANDOM_ALL)) {
/* try the original tuple first */
if (in_range(orig_tuple, range)) {
if (!nf_nat_used_tuple(orig_tuple, ct)) {
@ -582,7 +545,7 @@ get_unique_tuple(struct nf_conntrack_tuple *tuple,
*/
/* Only bother mapping if it's not already in range and unique */
if (!random_port) {
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) &&
l4proto_in_range(tuple, maniptype,

9
net/netfilter/nf_tables_api.c
View File

@ -8260,6 +8260,12 @@ void nf_tables_trans_destroy_flush_work(void)
}
EXPORT_SYMBOL_GPL(nf_tables_trans_destroy_flush_work);
static bool nft_expr_reduce(struct nft_regs_track *track,
const struct nft_expr *expr)
{
return false;
}
static int nf_tables_commit_chain_prepare(struct net *net, struct nft_chain *chain)
{
const struct nft_expr *expr, *last;
@ -8307,8 +8313,7 @@ static int nf_tables_commit_chain_prepare(struct net *net, struct nft_chain *cha
nft_rule_for_each_expr(expr, last, rule) {
track.cur = expr;
if (expr->ops->reduce &&
expr->ops->reduce(&track, expr)) {
if (nft_expr_reduce(&track, expr)) {
expr = track.cur;
continue;
}

5
tools/testing/selftests/netfilter/nft_nat.sh
View File

@ -880,9 +880,8 @@ EOF
return $ksft_skip
fi
# test default behaviour. Packet from ns1 to ns0 is not redirected
# due to automatic port translation.
test_port_shadow "default" "ROUTER"
# test default behaviour. Packet from ns1 to ns0 is redirected to ns2.
test_port_shadow "default" "CLIENT"
# test packet filter based mitigation: prevent forwarding of
# packets claiming to come from the service port.