From b33f413af46ec8dff7f222dbd5bc3bcec1502d3d Mon Sep 17 00:00:00 2001 From: Juraj Sloboda Date: Wed, 8 Feb 2017 23:54:21 -0800 Subject: Add handling of ICMP error packets in SNAT (VPP-629) Change-Id: I8d2022b7cb3ef3da736c085bccbb5b9c057a8d76 Signed-off-by: Juraj Sloboda --- src/plugins/snat/in2out.c | 197 ++++++++++++++++++++++++++++++++++++++++------ 1 file changed, 171 insertions(+), 26 deletions(-) (limited to 'src/plugins/snat/in2out.c') diff --git a/src/plugins/snat/in2out.c b/src/plugins/snat/in2out.c index b0047737..e30c913c 100644 --- a/src/plugins/snat/in2out.c +++ b/src/plugins/snat/in2out.c @@ -112,6 +112,7 @@ typedef enum { SNAT_IN2OUT_NEXT_LOOKUP, SNAT_IN2OUT_NEXT_DROP, SNAT_IN2OUT_NEXT_SLOW_PATH, + SNAT_IN2OUT_NEXT_ICMP_ERROR, SNAT_IN2OUT_N_NEXT, } snat_in2out_next_t; @@ -410,6 +411,10 @@ static u32 slow_path (snat_main_t *sm, vlib_buffer_t *b0, return next0; } +typedef struct { + u16 src_port, dst_port; +} tcp_udp_header_t; + static inline u32 icmp_in2out_slow_path (snat_main_t *sm, vlib_buffer_t * b0, ip4_header_t * ip0, @@ -419,67 +424,171 @@ static inline u32 icmp_in2out_slow_path (snat_main_t *sm, vlib_node_runtime_t * node, u32 next0, f64 now, - u32 cpu_index) + u32 cpu_index, + snat_session_t ** p_s0) { snat_session_key_t key0; - icmp_echo_header_t *echo0; + icmp_echo_header_t *echo0, *inner_echo0 = 0; + ip4_header_t *inner_ip0; + void *l4_header = 0; + icmp46_header_t *inner_icmp0; clib_bihash_kv_8_8_t kv0, value0; - snat_session_t * s0; + snat_session_t * s0 = 0; u32 new_addr0, old_addr0; u16 old_id0, new_id0; ip_csum_t sum0; + u16 checksum0; snat_runtime_t * rt = (snat_runtime_t *)node->runtime_data; + u8 is_error_message = 0; - if (PREDICT_FALSE(icmp0->type != ICMP4_echo_request)) - { - b0->error = node->errors[SNAT_IN2OUT_ERROR_BAD_ICMP_TYPE]; - return SNAT_IN2OUT_NEXT_DROP; - } - echo0 = (icmp_echo_header_t *)(icmp0+1); key0.addr = ip0->src_address; - key0.port = echo0->identifier; - key0.protocol = SNAT_PROTOCOL_ICMP; key0.fib_index = rx_fib_index0; + switch(icmp0->type) + { + case ICMP4_destination_unreachable: + case ICMP4_time_exceeded: + case ICMP4_parameter_problem: + case ICMP4_source_quench: + case ICMP4_redirect: + case ICMP4_alternate_host_address: + is_error_message = 1; + } + + if (!is_error_message) + { + if (PREDICT_FALSE(icmp0->type != ICMP4_echo_request)) + { + b0->error = node->errors[SNAT_IN2OUT_ERROR_BAD_ICMP_TYPE]; + next0 = SNAT_IN2OUT_NEXT_DROP; + goto out; + } + key0.protocol = SNAT_PROTOCOL_ICMP; + key0.port = echo0->identifier; + } + else + { + inner_ip0 = (ip4_header_t *)(echo0+1); + l4_header = ip4_next_header (inner_ip0); + key0.protocol = ip_proto_to_snat_proto (inner_ip0->protocol); + switch (key0.protocol) + { + case SNAT_PROTOCOL_ICMP: + inner_icmp0 = (icmp46_header_t*)l4_header; + inner_echo0 = (icmp_echo_header_t *)(inner_icmp0+1); + key0.port = inner_echo0->identifier; + break; + case SNAT_PROTOCOL_UDP: + case SNAT_PROTOCOL_TCP: + key0.port = ((tcp_udp_header_t*)l4_header)->dst_port; + break; + default: + b0->error = node->errors[SNAT_IN2OUT_ERROR_UNSUPPORTED_PROTOCOL]; + next0 = SNAT_IN2OUT_NEXT_DROP; + goto out; + } + } + kv0.key = key0.as_u64; if (clib_bihash_search_8_8 (&sm->in2out, &kv0, &value0)) { if (PREDICT_FALSE(snat_not_translate(sm, rt, sw_if_index0, ip0, IP_PROTOCOL_ICMP, rx_fib_index0))) - return next0; + goto out; + + if (is_error_message) + { + next0 = SNAT_IN2OUT_NEXT_DROP; + goto out; + } next0 = slow_path (sm, b0, ip0, rx_fib_index0, &key0, &s0, node, next0, cpu_index); if (PREDICT_FALSE (next0 == SNAT_IN2OUT_NEXT_DROP)) - return next0; + goto out; } else s0 = pool_elt_at_index (sm->per_thread_data[cpu_index].sessions, value0.value); + sum0 = ip_incremental_checksum (0, icmp0, + ntohs(ip0->length) - ip4_header_bytes (ip0)); + checksum0 = ~ip_csum_fold (sum0); + if (PREDICT_FALSE(checksum0 != 0 && checksum0 != 0xffff)) + { + next0 = SNAT_IN2OUT_NEXT_DROP; + goto out; + } + old_addr0 = ip0->src_address.as_u32; ip0->src_address = s0->out2in.addr; new_addr0 = ip0->src_address.as_u32; vnet_buffer(b0)->sw_if_index[VLIB_TX] = s0->out2in.fib_index; - + sum0 = ip0->checksum; - sum0 = ip_csum_update (sum0, old_addr0, new_addr0, - ip4_header_t, + sum0 = ip_csum_update (sum0, old_addr0, new_addr0, ip4_header_t, src_address /* changed member */); ip0->checksum = ip_csum_fold (sum0); - old_id0 = echo0->identifier; - new_id0 = s0->out2in.port; - echo0->identifier = new_id0; + if (!is_error_message) + { + old_id0 = echo0->identifier; + new_id0 = s0->out2in.port; + echo0->identifier = new_id0; - sum0 = icmp0->checksum; - sum0 = ip_csum_update (sum0, old_id0, new_id0, icmp_echo_header_t, - identifier); - icmp0->checksum = ip_csum_fold (sum0); + sum0 = icmp0->checksum; + sum0 = ip_csum_update (sum0, old_id0, new_id0, icmp_echo_header_t, + identifier); + icmp0->checksum = ip_csum_fold (sum0); + } + else + { + if (!ip4_header_checksum_is_valid (inner_ip0)) + { + next0 = SNAT_IN2OUT_NEXT_DROP; + goto out; + } + + old_addr0 = inner_ip0->dst_address.as_u32; + inner_ip0->dst_address = s0->out2in.addr; + new_addr0 = inner_ip0->src_address.as_u32; + + sum0 = icmp0->checksum; + sum0 = ip_csum_update (sum0, old_addr0, new_addr0, ip4_header_t, + dst_address /* changed member */); + icmp0->checksum = ip_csum_fold (sum0); + + switch (key0.protocol) + { + case SNAT_PROTOCOL_ICMP: + old_id0 = inner_echo0->identifier; + new_id0 = s0->out2in.port; + inner_echo0->identifier = new_id0; + + sum0 = icmp0->checksum; + sum0 = ip_csum_update (sum0, old_id0, new_id0, icmp_echo_header_t, + identifier); + icmp0->checksum = ip_csum_fold (sum0); + break; + case SNAT_PROTOCOL_UDP: + case SNAT_PROTOCOL_TCP: + old_id0 = ((tcp_udp_header_t*)l4_header)->dst_port; + new_id0 = s0->out2in.port; + ((tcp_udp_header_t*)l4_header)->dst_port = new_id0; + + sum0 = icmp0->checksum; + sum0 = ip_csum_update (sum0, old_id0, new_id0, tcp_udp_header_t, + dst_port); + icmp0->checksum = ip_csum_fold (sum0); + break; + default: + ASSERT(0); + } + } /* Accounting */ s0->last_heard = now; @@ -495,6 +604,8 @@ static inline u32 icmp_in2out_slow_path (snat_main_t *sm, s0->per_user_index); } +out: + *p_s0 = s0; return next0; } @@ -685,6 +796,16 @@ snat_in2out_node_fn_inline (vlib_main_t * vm, proto0 = ip_proto_to_snat_proto (ip0->protocol); + if (PREDICT_FALSE(ip0->ttl == 1)) + { + vnet_buffer (b0)->sw_if_index[VLIB_TX] = (u32) ~ 0; + icmp4_error_set_vnet_buffer (b0, ICMP4_time_exceeded, + ICMP4_time_exceeded_ttl_exceeded_in_transit, + 0); + next0 = SNAT_IN2OUT_NEXT_ICMP_ERROR; + goto trace00; + } + /* Next configured feature, probably ip4-lookup */ if (is_slow_path) { @@ -695,7 +816,7 @@ snat_in2out_node_fn_inline (vlib_main_t * vm, { next0 = icmp_in2out_slow_path (sm, b0, ip0, icmp0, sw_if_index0, rx_fib_index0, - node, next0, now, cpu_index); + node, next0, now, cpu_index, &s0); goto trace00; } } @@ -815,6 +936,16 @@ snat_in2out_node_fn_inline (vlib_main_t * vm, proto1 = ip_proto_to_snat_proto (ip1->protocol); + if (PREDICT_FALSE(ip0->ttl == 1)) + { + vnet_buffer (b1)->sw_if_index[VLIB_TX] = (u32) ~ 0; + icmp4_error_set_vnet_buffer (b1, ICMP4_time_exceeded, + ICMP4_time_exceeded_ttl_exceeded_in_transit, + 0); + next0 = SNAT_IN2OUT_NEXT_ICMP_ERROR; + goto trace01; + } + /* Next configured feature, probably ip4-lookup */ if (is_slow_path) { @@ -825,7 +956,7 @@ snat_in2out_node_fn_inline (vlib_main_t * vm, { next1 = icmp_in2out_slow_path (sm, b1, ip1, icmp1, sw_if_index1, rx_fib_index1, node, - next1, now, cpu_index); + next1, now, cpu_index, &s1); goto trace01; } } @@ -980,6 +1111,16 @@ snat_in2out_node_fn_inline (vlib_main_t * vm, proto0 = ip_proto_to_snat_proto (ip0->protocol); + if (PREDICT_FALSE(ip0->ttl == 1)) + { + vnet_buffer (b0)->sw_if_index[VLIB_TX] = (u32) ~ 0; + icmp4_error_set_vnet_buffer (b0, ICMP4_time_exceeded, + ICMP4_time_exceeded_ttl_exceeded_in_transit, + 0); + next0 = SNAT_IN2OUT_NEXT_ICMP_ERROR; + goto trace0; + } + /* Next configured feature, probably ip4-lookup */ if (is_slow_path) { @@ -990,7 +1131,7 @@ snat_in2out_node_fn_inline (vlib_main_t * vm, { next0 = icmp_in2out_slow_path (sm, b0, ip0, icmp0, sw_if_index0, rx_fib_index0, node, - next0, now, cpu_index); + next0, now, cpu_index, &s0); goto trace0; } } @@ -1020,6 +1161,7 @@ snat_in2out_node_fn_inline (vlib_main_t * vm, next0 = slow_path (sm, b0, ip0, rx_fib_index0, &key0, &s0, node, next0, cpu_index); + if (PREDICT_FALSE (next0 == SNAT_IN2OUT_NEXT_DROP)) goto trace0; } @@ -1141,6 +1283,7 @@ VLIB_REGISTER_NODE (snat_in2out_node) = { [SNAT_IN2OUT_NEXT_DROP] = "error-drop", [SNAT_IN2OUT_NEXT_LOOKUP] = "ip4-lookup", [SNAT_IN2OUT_NEXT_SLOW_PATH] = "snat-in2out-slowpath", + [SNAT_IN2OUT_NEXT_ICMP_ERROR] = "ip4-icmp-error", }, }; @@ -1173,6 +1316,7 @@ VLIB_REGISTER_NODE (snat_in2out_slowpath_node) = { [SNAT_IN2OUT_NEXT_DROP] = "error-drop", [SNAT_IN2OUT_NEXT_LOOKUP] = "ip4-lookup", [SNAT_IN2OUT_NEXT_SLOW_PATH] = "snat-in2out-slowpath", + [SNAT_IN2OUT_NEXT_ICMP_ERROR] = "ip4-icmp-error", }, }; @@ -1604,6 +1748,7 @@ VLIB_REGISTER_NODE (snat_in2out_fast_node) = { [SNAT_IN2OUT_NEXT_DROP] = "error-drop", [SNAT_IN2OUT_NEXT_LOOKUP] = "ip4-lookup", [SNAT_IN2OUT_NEXT_SLOW_PATH] = "snat-in2out-slowpath", + [SNAT_IN2OUT_NEXT_ICMP_ERROR] = "ip4-icmp-error", }, }; -- cgit 1.2.3-korg