[ovs-dev] [ovs-dev v5] ipf: add ipf context

Peng He xnhp0320 at gmail.com
Sat Nov 27 03:39:49 UTC 2021


From: Peng He <xnhp0320 at gmail.com>

ipf_postprocess will emit packets into the datapath pipeline ignoring
the conntrack context, this might casuse weird issues when a packet
batch has less space to hold all the fragments belonging to single
packet.

Given the below ruleest and consider sending a 64K ICMP packet which
is splitted into 64 fragments.

priority=1,action=drop
priority=10,arp,action=normal
priority=100,in_port=1,ct_state=-trk,icmp,action=ct(zone=9,table=0)
priority=100,in_port=1,ct_state=+new+trk,icmp,action=ct(zone=9,commit),2
priority=100,in_port=1,ct_state=-new+est+trk,icmp,action=2
priority=100,in_port=2,ct_state=-trk,icmp,action=ct(table=0,zone=9)
priority=100,in_port=2,ct_state=+trk+est-new,icmp,action=1

Batch 1:
the first 32 packets will be buffered in the ipf preprocessing, nothing
more proceeds.

Batch 2:
the second 32 packets succeed the fragment reassembly and goes to ct
and ipf_post will emits the first 32 packets due to the limit of batch
size.

the first 32 packets goes to the datapath again due to the
recirculation, and again buffered at ipf preprocessing before ct commit,
then the ovs tries to call ct commit as well as ipf_postprocessing which emits
the last 32 packets, in this case the last 32 packets will follow
the current actions which will be sent to port 2 directly without
recirculation and going to ipf preprocssing and ct commit again.

This will cause the first 32 packets never get the chance to
reassemble and evevntually this large ICMP packets fail to transmit.

this patch fixes this issue by adding firstly ipf context to avoid
ipf_postprocessing emits packets in the wrong context. Then by
re-executing the action list again to emit the last 32 packets
in the right context to correctly transmitting multiple fragments.

This might be one of the root cause why the OVS log warns:

"
skipping output to input port on bridge br-int while processing
"

As a pkt might enter into different ipf context.

Signed-off-by: Peng He <hepeng.0320 at bytedance.com>
Co-authored-by: Mike Pattrick <mkp at redhat.com>
---
 lib/conntrack.c         |  9 ++++---
 lib/conntrack.h         | 15 ++++++------
 lib/dpif-netdev.c       | 52 +++++++++++++++++++++++++++++++++++++----
 lib/ipf.c               | 40 ++++++++++++++++++++++++-------
 lib/ipf.h               | 11 +++++++--
 tests/system-traffic.at | 33 ++++++++++++++++++++++++++
 tests/test-conntrack.c  |  6 ++---
 7 files changed, 136 insertions(+), 30 deletions(-)

diff --git a/lib/conntrack.c b/lib/conntrack.c
index 33a1a9295..72999f1ae 100644
--- a/lib/conntrack.c
+++ b/lib/conntrack.c
@@ -1434,14 +1434,14 @@ process_one(struct conntrack *ct, struct dp_packet *pkt,
  * connection tables.  'setmark', if not NULL, should point to a two
  * elements array containing a value and a mask to set the connection mark.
  * 'setlabel' behaves similarly for the connection label.*/
-int
+bool
 conntrack_execute(struct conntrack *ct, struct dp_packet_batch *pkt_batch,
                   ovs_be16 dl_type, bool force, bool commit, uint16_t zone,
                   const uint32_t *setmark,
                   const struct ovs_key_ct_labels *setlabel,
                   ovs_be16 tp_src, ovs_be16 tp_dst, const char *helper,
                   const struct nat_action_info_t *nat_action_info,
-                  long long now, uint32_t tp_id)
+                  long long now, uint32_t tp_id, struct ipf_ctx *ipf_ctx)
 {
     ipf_preprocess_conntrack(ct->ipf, pkt_batch, now, dl_type, zone,
                              ct->hash_basis);
@@ -1468,9 +1468,8 @@ conntrack_execute(struct conntrack *ct, struct dp_packet_batch *pkt_batch,
         }
     }
 
-    ipf_postprocess_conntrack(ct->ipf, pkt_batch, now, dl_type);
-
-    return 0;
+    return ipf_postprocess_conntrack(ct->ipf, pkt_batch, ipf_ctx, \
+                                     now, dl_type);
 }
 
 void
diff --git a/lib/conntrack.h b/lib/conntrack.h
index 9553b188a..211efad3f 100644
--- a/lib/conntrack.h
+++ b/lib/conntrack.h
@@ -64,6 +64,7 @@
 struct dp_packet_batch;
 
 struct conntrack;
+struct ipf_ctx;
 
 union ct_addr {
     ovs_be32 ipv4;
@@ -88,13 +89,13 @@ struct nat_action_info_t {
 struct conntrack *conntrack_init(void);
 void conntrack_destroy(struct conntrack *);
 
-int conntrack_execute(struct conntrack *ct, struct dp_packet_batch *pkt_batch,
-                      ovs_be16 dl_type, bool force, bool commit, uint16_t zone,
-                      const uint32_t *setmark,
-                      const struct ovs_key_ct_labels *setlabel,
-                      ovs_be16 tp_src, ovs_be16 tp_dst, const char *helper,
-                      const struct nat_action_info_t *nat_action_info,
-                      long long now, uint32_t tp_id);
+bool conntrack_execute(struct conntrack *ct, struct dp_packet_batch *pkt_batch,
+                       ovs_be16 dl_type, bool force, bool commit,
+                       uint16_t zone, const uint32_t *setmark,
+                       const struct ovs_key_ct_labels *setlabel,
+                       ovs_be16 tp_src, ovs_be16 tp_dst, const char *helper,
+                       const struct nat_action_info_t *nat_action_info,
+                       long long now, uint32_t tp_id, struct ipf_ctx *ipf_ctx);
 void conntrack_clear(struct dp_packet *packet);
 
 struct conntrack_dump {
diff --git a/lib/dpif-netdev.c b/lib/dpif-netdev.c
index 98453a206..af928a6fa 100644
--- a/lib/dpif-netdev.c
+++ b/lib/dpif-netdev.c
@@ -7756,6 +7756,7 @@ dp_netdev_recirculate(struct dp_netdev_pmd_thread *pmd,
 struct dp_netdev_execute_aux {
     struct dp_netdev_pmd_thread *pmd;
     const struct flow *flow;
+    const struct nlattr *redo_actions;
 };
 
 static void
@@ -8285,10 +8286,23 @@ dp_execute_cb(void *aux_, struct dp_packet_batch *packets_,
             VLOG_WARN_RL(&rl, "NAT specified without commit.");
         }
 
-        conntrack_execute(dp->conntrack, packets_, aux->flow->dl_type, force,
-                          commit, zone, setmark, setlabel, aux->flow->tp_src,
-                          aux->flow->tp_dst, helper, nat_action_info_ref,
-                          pmd->ctx.now / 1000, tp_id);
+        bool more_pkts;
+        struct ipf_ctx ipf_ctx = { aux->flow->recirc_id,
+                                   aux->flow->in_port,
+                                   zone };
+        more_pkts = conntrack_execute(dp->conntrack, packets_,
+                                      aux->flow->dl_type,
+                                      force, commit, zone,
+                                      setmark, setlabel,
+                                      aux->flow->tp_src,
+                                      aux->flow->tp_dst,
+                                      helper, nat_action_info_ref,
+                                      pmd->ctx.now / 1000, tp_id, &ipf_ctx);
+        if (more_pkts) {
+            aux->redo_actions = a;
+        } else {
+            aux->redo_actions = NULL;
+        }
         break;
     }
 
@@ -8322,16 +8336,44 @@ dp_execute_cb(void *aux_, struct dp_packet_batch *packets_,
     dp_packet_delete_batch(packets_, should_steal);
 }
 
+static size_t
+dp_netdev_find_actions_left(const struct nlattr *actions,
+                            size_t actions_len,
+                            const struct nlattr *target)
+{
+    const struct nlattr *a;
+    size_t left;
+    NL_ATTR_FOR_EACH_UNSAFE (a, left, actions, actions_len) {
+        if (a == target) {
+            break;
+        }
+    }
+    return left;
+}
+
 static void
 dp_netdev_execute_actions(struct dp_netdev_pmd_thread *pmd,
                           struct dp_packet_batch *packets,
                           bool should_steal, const struct flow *flow,
                           const struct nlattr *actions, size_t actions_len)
 {
-    struct dp_netdev_execute_aux aux = { pmd, flow };
+    int max_reexec = 2;
+    struct dp_netdev_execute_aux aux = { pmd, flow, NULL };
 
     odp_execute_actions(&aux, packets, should_steal, actions,
                         actions_len, dp_execute_cb);
+
+    while (OVS_UNLIKELY(aux.redo_actions && max_reexec --)) {
+        struct dp_packet_batch batch;
+        dp_packet_batch_init(&batch);
+        size_t redo_actions_len = \
+                                  dp_netdev_find_actions_left(actions,
+                                          actions_len,
+                                          aux.redo_actions);
+
+        odp_execute_actions(&aux, &batch, should_steal,
+                aux.redo_actions, redo_actions_len, dp_execute_cb);
+    }
 }
 
 struct dp_netdev_ct_dump {
diff --git a/lib/ipf.c b/lib/ipf.c
index 507db2aea..1fd3d8d30 100644
--- a/lib/ipf.c
+++ b/lib/ipf.c
@@ -1046,30 +1046,52 @@ ipf_send_frags_in_list(struct ipf *ipf, struct ipf_list *ipf_list,
     OVS_NOT_REACHED();
 }
 
+static bool
+ipf_ctx_eq(struct ipf_list *ipf_list, struct ipf_ctx *ctx)
+{
+    struct dp_packet *pkt =
+        ipf_list->frag_list[ipf_list->last_sent_idx + 1].pkt;
+
+    if (pkt->md.recirc_id != ctx->recirc_id ||
+            pkt->md.in_port.odp_port != ctx->in_port.odp_port ||
+            pkt->md.ct_zone != ctx->zone) {
+        return false;
+    }
+    return true;
+}
+
 /* Adds fragments associated with a completed fragment list to a packet batch
  * to be processed by the calling application, typically conntrack. Also
  * cleans up the list context when it is empty.*/
-static void
+static bool
 ipf_send_completed_frags(struct ipf *ipf, struct dp_packet_batch *pb,
-                         long long now, bool v6)
+                         struct ipf_ctx *ctx, long long now, bool v6)
 {
     if (ovs_list_is_empty(&ipf->frag_complete_list)) {
-        return;
+        return false;
     }
 
+    bool more_pkts = false;
     ovs_mutex_lock(&ipf->ipf_lock);
     struct ipf_list *ipf_list, *next;
 
     LIST_FOR_EACH_SAFE (ipf_list, next, list_node, &ipf->frag_complete_list) {
+
+        if (ctx && !ipf_ctx_eq(ipf_list, ctx)) {
+            continue;
+        }
+
         if (ipf_send_frags_in_list(ipf, ipf_list, pb, IPF_FRAG_COMPLETED_LIST,
                                    v6, now)) {
             ipf_completed_list_clean(&ipf->frag_lists, ipf_list);
         } else {
+            more_pkts = true;
             break;
         }
     }
 
     ovs_mutex_unlock(&ipf->ipf_lock);
+    return more_pkts;
 }
 
 /* Conservatively adds fragments associated with a expired fragment list to
@@ -1225,8 +1247,8 @@ ipf_post_execute_reass_pkts(struct ipf *ipf,
  * be added to the batch to be sent through conntrack. */
 void
 ipf_preprocess_conntrack(struct ipf *ipf, struct dp_packet_batch *pb,
-                         long long now, ovs_be16 dl_type, uint16_t zone,
-                         uint32_t hash_basis)
+                         long long now, ovs_be16 dl_type,
+                         uint16_t zone, uint32_t hash_basis)
 {
     if (ipf_get_enabled(ipf)) {
         ipf_extract_frags_from_batch(ipf, pb, dl_type, zone, now, hash_basis);
@@ -1241,16 +1263,18 @@ ipf_preprocess_conntrack(struct ipf *ipf, struct dp_packet_batch *pb,
  * through conntrack and adds these fragments to any batches seen.  Expired
  * fragments are marked as invalid and also added to the batches seen
  * with low priority.  Reassembled packets are freed. */
-void
+bool
 ipf_postprocess_conntrack(struct ipf *ipf, struct dp_packet_batch *pb,
-                          long long now, ovs_be16 dl_type)
+                          struct ipf_ctx *ctx, long long now, ovs_be16 dl_type)
 {
+    bool more_pkts = false;
     if (ipf_get_enabled(ipf) || atomic_count_get(&ipf->nfrag)) {
         bool v6 = dl_type == htons(ETH_TYPE_IPV6);
         ipf_post_execute_reass_pkts(ipf, pb, v6);
-        ipf_send_completed_frags(ipf, pb, now, v6);
+        more_pkts = ipf_send_completed_frags(ipf, pb, ctx, now, v6);
         ipf_send_expired_frags(ipf, pb, now, v6);
     }
+    return more_pkts;
 }
 
 static void *
diff --git a/lib/ipf.h b/lib/ipf.h
index 6ac91b270..7bbf453af 100644
--- a/lib/ipf.h
+++ b/lib/ipf.h
@@ -40,14 +40,21 @@ struct ipf_status {
    unsigned int nfrag_max;
 };
 
+struct ipf_ctx {
+    uint32_t recirc_id;
+    union flow_in_port in_port; /* Input port. */
+    uint16_t zone;
+};
+
 struct ipf *ipf_init(void);
 void ipf_destroy(struct ipf *ipf);
 void ipf_preprocess_conntrack(struct ipf *ipf, struct dp_packet_batch *pb,
                               long long now, ovs_be16 dl_type, uint16_t zone,
                               uint32_t hash_basis);
 
-void ipf_postprocess_conntrack(struct ipf *ipf, struct dp_packet_batch *pb,
-                               long long now, ovs_be16 dl_type);
+bool ipf_postprocess_conntrack(struct ipf *ipf, struct dp_packet_batch *pb,
+                               struct ipf_ctx *ctx, long long now,
+                               ovs_be16 dl_type);
 
 int ipf_set_enabled(struct ipf *ipf, bool v6, bool enable);
 int ipf_set_min_frag(struct ipf *ipf, bool v6, uint32_t value);
diff --git a/tests/system-traffic.at b/tests/system-traffic.at
index a69896d33..a09318882 100644
--- a/tests/system-traffic.at
+++ b/tests/system-traffic.at
@@ -2741,6 +2741,39 @@ DPCTL_CHECK_FRAGMENTATION_PASS()
 OVS_TRAFFIC_VSWITCHD_STOP
 AT_CLEANUP
 
+AT_SETUP([conntrack - IPv4 large fragmentation])
+CHECK_CONNTRACK()
+OVS_TRAFFIC_VSWITCHD_START()
+
+ADD_NAMESPACES(at_ns0, at_ns1)
+
+ADD_VETH(p0, at_ns0, br0, "10.1.1.1/24")
+ADD_VETH(p1, at_ns1, br0, "10.1.1.2/24")
+
+dnl Sending ping through conntrack
+AT_DATA([flows.txt], [dnl
+priority=1,action=drop
+priority=10,arp,action=normal
+priority=100,in_port=1,ct_state=-trk,icmp,action=ct(zone=9,table=0)
+priority=100,in_port=1,ct_state=+new+trk,icmp,action=ct(zone=9,commit),2
+priority=100,in_port=1,ct_state=-new+est+trk,icmp,action=2
+priority=100,in_port=2,ct_state=-trk,icmp,action=ct(table=0,zone=9)
+priority=100,in_port=2,ct_state=+trk+est-new,icmp,action=1
+])
+
+AT_CHECK([ovs-ofctl --bundle add-flows br0 flows.txt])
+
+dnl Modify userspace conntrack fragmentation handling.
+DPCTL_MODIFY_FRAGMENTATION()
+
+dnl Ipv4 larger fragmentation connectivity check.
+NS_CHECK_EXEC([at_ns0], [ping -s 65000 -q -c 3 -i 0.3 -w 2 10.1.1.2 | FORMAT_PING], [0], [dnl
+3 packets transmitted, 3 received, 0% packet loss, time 0ms
+])
+
+OVS_TRAFFIC_VSWITCHD_STOP
+AT_CLEANUP
+
 AT_SETUP([conntrack - IPv4 fragmentation expiry])
 CHECK_CONNTRACK()
 OVS_TRAFFIC_VSWITCHD_START()
diff --git a/tests/test-conntrack.c b/tests/test-conntrack.c
index 24c93e4a4..f90b7aa78 100644
--- a/tests/test-conntrack.c
+++ b/tests/test-conntrack.c
@@ -91,7 +91,7 @@ ct_thread_main(void *aux_)
     ovs_barrier_block(&barrier);
     for (i = 0; i < n_pkts; i += batch_size) {
         conntrack_execute(ct, pkt_batch, dl_type, false, true, 0, NULL, NULL,
-                          0, 0, NULL, NULL, now, 0);
+                          0, 0, NULL, NULL, now, 0, NULL);
         DP_PACKET_BATCH_FOR_EACH (j, pkt, pkt_batch) {
             pkt_metadata_init_conn(&pkt->md);
         }
@@ -178,7 +178,7 @@ pcap_batch_execute_conntrack(struct conntrack *ct_,
 
         if (flow.dl_type != dl_type) {
             conntrack_execute(ct_, &new_batch, dl_type, false, true, 0,
-                              NULL, NULL, 0, 0, NULL, NULL, now, 0);
+                              NULL, NULL, 0, 0, NULL, NULL, now, 0, NULL);
             dp_packet_batch_init(&new_batch);
         }
         dp_packet_batch_add(&new_batch, packet);
@@ -186,7 +186,7 @@ pcap_batch_execute_conntrack(struct conntrack *ct_,
 
     if (!dp_packet_batch_is_empty(&new_batch)) {
         conntrack_execute(ct_, &new_batch, dl_type, false, true, 0, NULL, NULL,
-                          0, 0, NULL, NULL, now, 0);
+                          0, 0, NULL, NULL, now, 0, NULL);
     }
 
 }
-- 
2.25.1



More information about the dev mailing list