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authorOle Troan <ot@cisco.com>2021-08-11 13:54:14 +0200
committerNeale Ranns <neale@graphiant.com>2021-08-13 18:07:23 +0000
commit8034a36a9cedc95f6762bf0a07f6617d0bf69bfe (patch)
treed22313b64c46a26c5c46fcf8c2cb799b02e92197 /src/vnet/ip
parentd170681b24724c522adaf1e2f4f0e1f3289dbf82 (diff)
ip: source address selection
Implement a simple source address selection algorithm for IPv4 and IPv6. IPv6 does not yet implement RFC6724 but supports link-locals. ping now chooses correct source address for link-local destination. Added ping support for link-local multicast (e.g. allnodes). Type: feature Signed-off-by: Ole Troan <ot@cisco.com> Change-Id: I1a3382c1f7d4ace0386c2c19e4e47b045b73a3ed Signed-off-by: Ole Troan <ot@cisco.com>
Diffstat (limited to 'src/vnet/ip')
-rw-r--r--src/vnet/ip/icmp4.c26
-rw-r--r--src/vnet/ip/icmp6.c21
-rw-r--r--src/vnet/ip/ip_sas.c214
-rw-r--r--src/vnet/ip/ip_sas.h32
4 files changed, 259 insertions, 34 deletions
diff --git a/src/vnet/ip/icmp4.c b/src/vnet/ip/icmp4.c
index 0363092d5d5..5f9ffa3b2b7 100644
--- a/src/vnet/ip/icmp4.c
+++ b/src/vnet/ip/icmp4.c
@@ -40,6 +40,7 @@
#include <vlib/vlib.h>
#include <vnet/ip/ip.h>
#include <vnet/pg/pg.h>
+#include <vnet/ip/ip_sas.h>
static char *icmp_error_strings[] = {
#define _(f,s) s,
@@ -254,8 +255,6 @@ ip4_icmp_error (vlib_main_t * vm,
u32 *from, *to_next;
uword n_left_from, n_left_to_next;
ip4_icmp_error_next_t next_index;
- ip4_main_t *im = &ip4_main;
- ip_lookup_main_t *lm = &im->lookup_main;
from = vlib_frame_vector_args (frame);
n_left_from = frame->n_vectors;
@@ -286,7 +285,7 @@ ip4_icmp_error (vlib_main_t * vm,
vlib_buffer_t *p0, *org_p0;
ip4_header_t *ip0, *out_ip0;
icmp46_header_t *icmp0;
- u32 sw_if_index0, if_add_index0;
+ u32 sw_if_index0;
ip_csum_t sum;
org_p0 = vlib_get_buffer (vm, org_pi0);
@@ -323,25 +322,14 @@ ip4_icmp_error (vlib_main_t * vm,
out_ip0->ttl = 0xff;
out_ip0->protocol = IP_PROTOCOL_ICMP;
out_ip0->dst_address = ip0->src_address;
- if_add_index0 = ~0;
- if (PREDICT_TRUE (vec_len (lm->if_address_pool_index_by_sw_if_index)
- > sw_if_index0))
- if_add_index0 =
- lm->if_address_pool_index_by_sw_if_index[sw_if_index0];
- if (PREDICT_TRUE (if_add_index0 != ~0))
- {
- ip_interface_address_t *if_add =
- pool_elt_at_index (lm->if_address_pool, if_add_index0);
- ip4_address_t *if_ip =
- ip_interface_address_get_address (lm, if_add);
- out_ip0->src_address = *if_ip;
- }
- else
- {
- /* interface has no IP4 address - should not happen */
+ /* Prefer a source address from "offending interface" */
+ if (!ip4_sas_by_sw_if_index (sw_if_index0, &out_ip0->dst_address,
+ &out_ip0->src_address))
+ { /* interface has no IP6 address - should not happen */
next0 = IP4_ICMP_ERROR_NEXT_DROP;
error0 = ICMP4_ERROR_DROP;
}
+
out_ip0->checksum = ip4_header_checksum (out_ip0);
/* Fill icmp header fields */
diff --git a/src/vnet/ip/icmp6.c b/src/vnet/ip/icmp6.c
index 4bba430fadc..b6ed3ea0ec9 100644
--- a/src/vnet/ip/icmp6.c
+++ b/src/vnet/ip/icmp6.c
@@ -40,6 +40,7 @@
#include <vlib/vlib.h>
#include <vnet/ip/ip.h>
#include <vnet/pg/pg.h>
+#include <vnet/ip/ip_sas.h>
static u8 *
format_ip6_icmp_type_and_code (u8 * s, va_list * args)
@@ -475,8 +476,6 @@ ip6_icmp_error (vlib_main_t * vm,
u32 *from, *to_next;
uword n_left_from, n_left_to_next;
ip6_icmp_error_next_t next_index;
- ip6_main_t *im = &ip6_main;
- ip_lookup_main_t *lm = &im->lookup_main;
from = vlib_frame_vector_args (frame);
n_left_from = frame->n_vectors;
@@ -507,7 +506,7 @@ ip6_icmp_error (vlib_main_t * vm,
vlib_buffer_t *p0, *org_p0;
ip6_header_t *ip0, *out_ip0;
icmp46_header_t *icmp0;
- u32 sw_if_index0, if_add_index0;
+ u32 sw_if_index0;
int bogus_length;
org_p0 = vlib_get_buffer (vm, org_pi0);
@@ -547,18 +546,10 @@ ip6_icmp_error (vlib_main_t * vm,
out_ip0->protocol = IP_PROTOCOL_ICMP6;
out_ip0->hop_limit = 0xff;
out_ip0->dst_address = ip0->src_address;
- if_add_index0 =
- lm->if_address_pool_index_by_sw_if_index[sw_if_index0];
- if (PREDICT_TRUE (if_add_index0 != ~0))
- {
- ip_interface_address_t *if_add =
- pool_elt_at_index (lm->if_address_pool, if_add_index0);
- ip6_address_t *if_ip =
- ip_interface_address_get_address (lm, if_add);
- out_ip0->src_address = *if_ip;
- }
- else /* interface has no IP6 address - should not happen */
- {
+ /* Prefer a source address from "offending interface" */
+ if (!ip6_sas_by_sw_if_index (sw_if_index0, &out_ip0->dst_address,
+ &out_ip0->src_address))
+ { /* interface has no IP6 address - should not happen */
next0 = IP6_ICMP_ERROR_NEXT_DROP;
error0 = ICMP6_ERROR_DROP;
}
diff --git a/src/vnet/ip/ip_sas.c b/src/vnet/ip/ip_sas.c
new file mode 100644
index 00000000000..7d3632d95ed
--- /dev/null
+++ b/src/vnet/ip/ip_sas.c
@@ -0,0 +1,214 @@
+/*
+ * Copyright (c) 2021 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "ip_sas.h"
+#include <vppinfra/types.h>
+#include <vnet/ip/ip_interface.h>
+#include <vnet/fib/fib_table.h>
+#include <vnet/ip/ip6_link.h>
+#include <vppinfra/byte_order.h>
+
+/*
+ * This file implement source address selection for VPP applications
+ * (e.g. ping, DNS, ICMP)
+ * It does not yet implement full fledged RFC6724 SAS.
+ * SAS assumes every IP enabled interface has an address. The algorithm will
+ * not go and hunt for a suitable IP address on other interfaces than the
+ * output interface or the specified preferred sw_if_index.
+ * That means that an interface with just an IPv6 link-local address must also
+ * be configured with an unnumbered configuration pointing to a numbered
+ * interface.
+ */
+
+static int
+ip6_sas_commonlen (const ip6_address_t *a1, const ip6_address_t *a2)
+{
+ u64 fa = clib_net_to_host_u64 (a1->as_u64[0]) ^
+ clib_net_to_host_u64 (a2->as_u64[0]);
+ if (fa == 0)
+ {
+ u64 la = clib_net_to_host_u64 (a1->as_u64[1]) ^
+ clib_net_to_host_u64 (a2->as_u64[1]);
+ if (la == 0)
+ return 128;
+ return 64 + __builtin_clzll (la);
+ }
+ else
+ {
+ return __builtin_clzll (fa);
+ }
+}
+
+static int
+ip4_sas_commonlen (const ip4_address_t *a1, const ip4_address_t *a2)
+{
+ u64 a =
+ clib_net_to_host_u32 (a1->as_u32) ^ clib_net_to_host_u32 (a2->as_u32);
+ if (a == 0)
+ return 32;
+ return __builtin_clz (a);
+}
+
+/*
+ * walk all addresses on an interface:
+ * - prefer a source matching the scope of the destination address.
+ * - last resort pick the source address with the longest
+ * common prefix with destination
+ * NOTE: This should at some point implement RFC6724.
+ */
+bool
+ip6_sas_by_sw_if_index (u32 sw_if_index, const ip6_address_t *dst,
+ ip6_address_t *src)
+{
+ ip_interface_address_t *ia = 0;
+ ip_lookup_main_t *lm6 = &ip6_main.lookup_main;
+ ip6_address_t *tmp, *bestsrc = 0;
+ int bestlen = 0, l;
+
+ if (ip6_address_is_link_local_unicast (dst) ||
+ dst->as_u32[0] == clib_host_to_net_u32 (0xff020000))
+ {
+ ip6_address_copy (src, ip6_get_link_local_address (sw_if_index));
+ return true;
+ }
+
+ foreach_ip_interface_address (
+ lm6, ia, sw_if_index, 1, ({
+ if (ia->flags & IP_INTERFACE_ADDRESS_FLAG_STALE)
+ continue;
+ tmp = ip_interface_address_get_address (lm6, ia);
+ l = ip6_sas_commonlen (tmp, dst);
+ if (l > bestlen || bestsrc == 0)
+ {
+ bestsrc = tmp;
+ bestlen = l;
+ }
+ }));
+ if (bestsrc)
+ {
+ ip6_address_copy (src, bestsrc);
+ return true;
+ }
+ return false;
+}
+
+/*
+ * walk all addresses on an interface and pick the source address with the
+ * longest common prefix with destination.
+ */
+bool
+ip4_sas_by_sw_if_index (u32 sw_if_index, const ip4_address_t *dst,
+ ip4_address_t *src)
+{
+ ip_interface_address_t *ia = 0;
+ ip_lookup_main_t *lm4 = &ip4_main.lookup_main;
+ ip4_address_t *tmp, *bestsrc = 0;
+ int bestlen = 0, l;
+
+ foreach_ip_interface_address (
+ lm4, ia, sw_if_index, 1, ({
+ if (ia->flags & IP_INTERFACE_ADDRESS_FLAG_STALE)
+ continue;
+ tmp = ip_interface_address_get_address (lm4, ia);
+ l = ip4_sas_commonlen (tmp, dst);
+ if (l > bestlen || bestsrc == 0)
+ {
+ bestsrc = tmp;
+ bestlen = l;
+ }
+ }));
+ if (bestsrc)
+ {
+ src->as_u32 = bestsrc->as_u32;
+ return true;
+ }
+ return false;
+}
+
+/*
+ * table_id must be set. Default = 0.
+ * sw_if_index is the interface to pick SA from otherwise ~0 will pick from
+ * outbound interface.
+ *
+ * NOTE: What to do if multiple output interfaces?
+ *
+ */
+bool
+ip6_sas (u32 table_id, u32 sw_if_index, const ip6_address_t *dst,
+ ip6_address_t *src)
+{
+ fib_prefix_t prefix;
+ u32 if_index = sw_if_index;
+
+ /* If sw_if_index is not specified use the output interface. */
+ if (sw_if_index == ~0)
+ {
+ clib_memcpy (&prefix.fp_addr.ip6, dst, sizeof (*dst));
+ prefix.fp_proto = FIB_PROTOCOL_IP6;
+ prefix.fp_len = 128;
+
+ u32 fib_index = fib_table_find (prefix.fp_proto, table_id);
+ if (fib_index == (u32) ~0)
+ return false;
+
+ fib_node_index_t fei = fib_table_lookup (fib_index, &prefix);
+ if (fei == FIB_NODE_INDEX_INVALID)
+ return false;
+
+ u32 output_sw_if_index = fib_entry_get_resolving_interface (fei);
+ if (output_sw_if_index == ~0)
+ return false;
+ if_index = output_sw_if_index;
+ }
+ return ip6_sas_by_sw_if_index (if_index, dst, src);
+}
+
+/*
+ * table_id must be set. Default = 0.
+ * sw_if_index is the interface to pick SA from otherwise ~0 will pick from
+ * outbound interface.
+ *
+ * NOTE: What to do if multiple output interfaces?
+ *
+ */
+bool
+ip4_sas (u32 table_id, u32 sw_if_index, const ip4_address_t *dst,
+ ip4_address_t *src)
+{
+ fib_prefix_t prefix;
+ u32 if_index = sw_if_index;
+
+ /* If sw_if_index is not specified use the output interface. */
+ if (sw_if_index == ~0)
+ {
+ clib_memcpy (&prefix.fp_addr.ip4, dst, sizeof (*dst));
+ prefix.fp_proto = FIB_PROTOCOL_IP4;
+ prefix.fp_len = 32;
+
+ u32 fib_index = fib_table_find (prefix.fp_proto, table_id);
+ if (fib_index == (u32) ~0)
+ return false;
+
+ fib_node_index_t fei = fib_table_lookup (fib_index, &prefix);
+ if (fei == FIB_NODE_INDEX_INVALID)
+ return false;
+
+ u32 output_sw_if_index = fib_entry_get_resolving_interface (fei);
+ if (output_sw_if_index == ~0)
+ return false;
+ if_index = output_sw_if_index;
+ }
+ return ip4_sas_by_sw_if_index (if_index, dst, src);
+}
diff --git a/src/vnet/ip/ip_sas.h b/src/vnet/ip/ip_sas.h
new file mode 100644
index 00000000000..b1e9e732ed9
--- /dev/null
+++ b/src/vnet/ip/ip_sas.h
@@ -0,0 +1,32 @@
+/*
+ * Copyright (c) 2021 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef included_ip_sas_h
+#define included_ip_sas_h
+
+#include <stdbool.h>
+#include <vnet/ip/ip6_packet.h>
+#include <vnet/ip/ip4_packet.h>
+
+bool ip6_sas_by_sw_if_index (u32 sw_if_index, const ip6_address_t *dst,
+ ip6_address_t *src);
+bool ip4_sas_by_sw_if_index (u32 sw_if_index, const ip4_address_t *dst,
+ ip4_address_t *src);
+bool ip6_sas (u32 table_id, u32 sw_if_index, const ip6_address_t *dst,
+ ip6_address_t *src);
+bool ip4_sas (u32 table_id, u32 sw_if_index, const ip4_address_t *dst,
+ ip4_address_t *src);
+
+#endif