From a82c25c366b0963d33ddf699196e6cf57f6d89b1 Mon Sep 17 00:00:00 2001 From: Florian Westphal Date: Tue, 8 Mar 2022 13:52:11 +0100 Subject: Revert "netfilter: nat: force port remap to prevent shadowing well-known ports" This reverts commit 878aed8db324bec64f3c3f956e64d5ae7375a5de. This change breaks existing setups where conntrack is used with asymmetric paths. In these cases, the NAT transformation occurs on the syn-ack instead of the syn: 1. SYN x:12345 -> y -> 443 // sent by initiator, receiverd by responder 2. SYNACK y:443 -> x:12345 // First packet seen by conntrack, as sent by responder 3. tuple_force_port_remap() gets called, sees: 'tcp from 443 to port 12345 NAT' -> pick a new source port, inititor receives 4. SYNACK y:$RANDOM -> x:12345 // connection is never established While its possible to avoid the breakage with NOTRACK rules, a kernel update should not break working setups. An alternative to the revert is to augment conntrack to tag mid-stream connections plus more code in the nat core to skip NAT for such connections, however, this leads to more interaction/integration between conntrack and NAT. Therefore, revert, users will need to add explicit nat rules to avoid port shadowing. Link: https://lore.kernel.org/netfilter-devel/20220302105908.GA5852@breakpoint.cc/#R Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2051413 Signed-off-by: Florian Westphal --- net/netfilter/nf_nat_core.c | 43 +++---------------------------------------- 1 file changed, 3 insertions(+), 40 deletions(-) (limited to 'net') diff --git a/net/netfilter/nf_nat_core.c b/net/netfilter/nf_nat_core.c index 2d06a66899b2..ffcf6529afc3 100644 --- a/net/netfilter/nf_nat_core.c +++ b/net/netfilter/nf_nat_core.c @@ -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, -- cgit From ee0a4dc9f317fb9a97f20037d219802ca8de939b Mon Sep 17 00:00:00 2001 From: Florian Westphal Date: Tue, 8 Mar 2022 17:28:38 +0100 Subject: Revert "netfilter: conntrack: tag conntracks picked up in local out hook" This was a prerequisite for the ill-fated "netfilter: nat: force port remap to prevent shadowing well-known ports". As this has been reverted, this change can be backed out too. Signed-off-by: Florian Westphal --- net/netfilter/nf_conntrack_core.c | 3 --- 1 file changed, 3 deletions(-) (limited to 'net') diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c index d6aa5b47031e..bf1e17c678f1 100644 --- a/net/netfilter/nf_conntrack_core.c +++ b/net/netfilter/nf_conntrack_core.c @@ -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); -- cgit From ed5f85d4229010235eab1e3d9acf6970d9304963 Mon Sep 17 00:00:00 2001 From: Pablo Neira Ayuso Date: Sat, 12 Mar 2022 11:05:46 +0100 Subject: netfilter: nf_tables: disable register tracking The register tracking infrastructure is incomplete, it might lead to generating incorrect ruleset bytecode, disable it by now given we are late in the release process. Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nf_tables_api.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) (limited to 'net') diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c index c86748b3873b..d71a33ae39b3 100644 --- a/net/netfilter/nf_tables_api.c +++ b/net/netfilter/nf_tables_api.c @@ -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; } -- cgit