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authorKlement Sekera <ksekera@cisco.com>2021-06-22 15:56:36 +0200
committerOle Tr�an <otroan@employees.org>2021-06-23 17:18:35 +0000
commite506fbc9fef063e437425f5c7f2d9b1e26d90766 (patch)
tree56119f94ee96b4e6d2733ade1a6643a44ae993cd /src/plugins/nat/nat44-ed/nat44_ed.c
parentda5088c9306cafbe71e90f7ebd8a411488afb121 (diff)
nat: ICMP handling fixes
If ICMP comes from a router on path, source address must not be rewritten in o2i path to avoid getting wrong checksum. Fix ICMP checksum computations. Type: fix Signed-off-by: Klement Sekera <ksekera@cisco.com> Change-Id: I035debccf966d7dbd63c364cb1e43380d641f708
Diffstat (limited to 'src/plugins/nat/nat44-ed/nat44_ed.c')
-rw-r--r--src/plugins/nat/nat44-ed/nat44_ed.c107
1 files changed, 94 insertions, 13 deletions
diff --git a/src/plugins/nat/nat44-ed/nat44_ed.c b/src/plugins/nat/nat44-ed/nat44_ed.c
index d42d303d95c..1a996cd16f7 100644
--- a/src/plugins/nat/nat44-ed/nat44_ed.c
+++ b/src/plugins/nat/nat44-ed/nat44_ed.c
@@ -3276,7 +3276,7 @@ static_always_inline int nat_6t_flow_icmp_translate (snat_main_t *sm,
static_always_inline void
nat_6t_flow_ip4_translate (snat_main_t *sm, vlib_buffer_t *b, ip4_header_t *ip,
nat_6t_flow_t *f, nat_protocol_t proto,
- int is_icmp_inner_ip4)
+ int is_icmp_inner_ip4, int skip_saddr_rewrite)
{
udp_header_t *udp = ip4_next_header (ip);
tcp_header_t *tcp = (tcp_header_t *) udp;
@@ -3319,7 +3319,10 @@ nat_6t_flow_ip4_translate (snat_main_t *sm, vlib_buffer_t *b, ip4_header_t *ip,
{
if (!is_icmp_inner_ip4)
{ // regular case
- ip->src_address = f->rewrite.saddr;
+ if (!skip_saddr_rewrite)
+ {
+ ip->src_address = f->rewrite.saddr;
+ }
ip->dst_address = f->rewrite.daddr;
}
else
@@ -3329,9 +3332,16 @@ nat_6t_flow_ip4_translate (snat_main_t *sm, vlib_buffer_t *b, ip4_header_t *ip,
}
}
- ip_csum_t ip_sum = ip->checksum;
- ip_sum = ip_csum_sub_even (ip_sum, f->l3_csum_delta);
- ip->checksum = ip_csum_fold (ip_sum);
+ if (skip_saddr_rewrite)
+ {
+ ip->checksum = ip4_header_checksum (ip);
+ }
+ else
+ {
+ ip_csum_t ip_sum = ip->checksum;
+ ip_sum = ip_csum_sub_even (ip_sum, f->l3_csum_delta);
+ ip->checksum = ip_csum_fold (ip_sum);
+ }
if (0xffff == ip->checksum)
ip->checksum = 0;
ASSERT (ip4_header_checksum_is_valid (ip));
@@ -3378,16 +3388,53 @@ nat_6t_flow_icmp_translate (snat_main_t *sm, vlib_buffer_t *b,
nat_protocol_t inner_proto =
ip_proto_to_nat_proto (inner_ip->protocol);
- ip_csum_t icmp_sum = icmp->checksum;
+ ip_csum_t old_icmp_sum = icmp->checksum;
+ ip_csum_t old_inner_ip_sum = inner_ip->checksum;
+ ip_csum_t old_udp_sum;
+ ip_csum_t old_tcp_sum;
+ ip_csum_t new_icmp_sum;
+ udp_header_t *udp;
+ tcp_header_t *tcp;
switch (inner_proto)
{
case NAT_PROTOCOL_UDP:
+ udp = (udp_header_t *) (inner_ip + 1);
+ old_udp_sum = udp->checksum;
+ nat_6t_flow_ip4_translate (sm, b, inner_ip, f, inner_proto,
+ 1 /* is_icmp_inner_ip4 */,
+ 0 /* skip_saddr_rewrite */);
+ new_icmp_sum = ip_csum_sub_even (old_icmp_sum, f->l3_csum_delta);
+ new_icmp_sum = ip_csum_sub_even (new_icmp_sum, f->l4_csum_delta);
+ new_icmp_sum =
+ ip_csum_update (new_icmp_sum, old_inner_ip_sum,
+ inner_ip->checksum, ip4_header_t, checksum);
+ new_icmp_sum =
+ ip_csum_update (new_icmp_sum, old_udp_sum, udp->checksum,
+ udp_header_t, checksum);
+ new_icmp_sum = ip_csum_fold (new_icmp_sum);
+ if (0xffff == new_icmp_sum)
+ new_icmp_sum = 0;
+ icmp->checksum = new_icmp_sum;
+ break;
case NAT_PROTOCOL_TCP:
+ tcp = (tcp_header_t *) (inner_ip + 1);
+ old_tcp_sum = tcp->checksum;
nat_6t_flow_ip4_translate (sm, b, inner_ip, f, inner_proto,
- 1 /* is_icmp_inner_ip4 */);
- icmp_sum = ip_csum_sub_even (icmp_sum, f->l3_csum_delta);
- icmp->checksum = ip_csum_fold (icmp_sum);
+ 1 /* is_icmp_inner_ip4 */,
+ 0 /* skip_saddr_rewrite */);
+ new_icmp_sum = ip_csum_sub_even (old_icmp_sum, f->l3_csum_delta);
+ new_icmp_sum = ip_csum_sub_even (new_icmp_sum, f->l4_csum_delta);
+ new_icmp_sum =
+ ip_csum_update (new_icmp_sum, old_inner_ip_sum,
+ inner_ip->checksum, ip4_header_t, checksum);
+ new_icmp_sum =
+ ip_csum_update (new_icmp_sum, old_tcp_sum, tcp->checksum,
+ tcp_header_t, checksum);
+ new_icmp_sum = ip_csum_fold (new_icmp_sum);
+ if (0xffff == new_icmp_sum)
+ new_icmp_sum = 0;
+ icmp->checksum = new_icmp_sum;
break;
case NAT_PROTOCOL_ICMP:
if (f->ops & NAT_FLOW_OP_ICMP_ID_REWRITE)
@@ -3417,29 +3464,63 @@ nat_6t_flow_icmp_translate (snat_main_t *sm, vlib_buffer_t *b,
}
}
}
+
return NAT_ED_TRNSL_ERR_SUCCESS;
}
-nat_translation_error_e
+static_always_inline nat_translation_error_e
nat_6t_flow_buf_translate (snat_main_t *sm, vlib_buffer_t *b, ip4_header_t *ip,
nat_6t_flow_t *f, nat_protocol_t proto,
- int is_output_feature)
+ int is_output_feature, int is_i2o)
{
if (!is_output_feature && f->ops & NAT_FLOW_OP_TXFIB_REWRITE)
{
vnet_buffer (b)->sw_if_index[VLIB_TX] = f->rewrite.fib_index;
}
- nat_6t_flow_ip4_translate (sm, b, ip, f, proto, 0 /* is_icmp_inner_ip4 */);
-
if (NAT_PROTOCOL_ICMP == proto)
{
+ if (ip->src_address.as_u32 != f->rewrite.saddr.as_u32)
+ {
+ // packet is returned from a router, not from destination
+ // skip source address rewrite if in o2i path
+ nat_6t_flow_ip4_translate (sm, b, ip, f, proto,
+ 0 /* is_icmp_inner_ip4 */,
+ !is_i2o /* skip_saddr_rewrite */);
+ }
+ else
+ {
+ nat_6t_flow_ip4_translate (sm, b, ip, f, proto,
+ 0 /* is_icmp_inner_ip4 */,
+ 0 /* skip_saddr_rewrite */);
+ }
return nat_6t_flow_icmp_translate (sm, b, ip, f);
}
+ nat_6t_flow_ip4_translate (sm, b, ip, f, proto, 0 /* is_icmp_inner_ip4 */,
+ 0 /* skip_saddr_rewrite */);
+
return NAT_ED_TRNSL_ERR_SUCCESS;
}
+nat_translation_error_e
+nat_6t_flow_buf_translate_i2o (snat_main_t *sm, vlib_buffer_t *b,
+ ip4_header_t *ip, nat_6t_flow_t *f,
+ nat_protocol_t proto, int is_output_feature)
+{
+ return nat_6t_flow_buf_translate (sm, b, ip, f, proto, is_output_feature,
+ 1 /* is_i2o */);
+}
+
+nat_translation_error_e
+nat_6t_flow_buf_translate_o2i (snat_main_t *sm, vlib_buffer_t *b,
+ ip4_header_t *ip, nat_6t_flow_t *f,
+ nat_protocol_t proto, int is_output_feature)
+{
+ return nat_6t_flow_buf_translate (sm, b, ip, f, proto, is_output_feature,
+ 0 /* is_i2o */);
+}
+
u8 *
format_nat_6t (u8 *s, va_list *args)
{