Add the datapath filtering for policy verdict logs.

Generate policy verdict logs only if the endpoint does have a network policy enforced on the direction of the traffic. Signed-off-by: Zang Li <zangli@google.com>
cilium · Mar 27, 2020 · 300236c · 300236c
1 parent 5ff7c51
commit 300236c
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Showing 9 changed files with 76 additions and 22 deletions.
diff --git a/bpf/lib/policy_log.h b/bpf/lib/policy_log.h
@@ -15,6 +15,12 @@
 #include "common.h"
 
 #ifdef POLICY_VERDICT_NOTIFY
+
+#ifndef POLICY_VERDICT_LOG_FILTER
+DEFINE_U32(POLICY_VERDICT_LOG_FILTER, 0xffff);
+#define POLICY_VERDICT_LOG_FILTER fetch_u32(POLICY_VERDICT_LOG_FILTER)
+#endif
+
 struct policy_verdict_notify {
 	NOTIFY_CAPTURE_HDR
 	__u32	remote_label;
@@ -28,11 +34,23 @@ struct policy_verdict_notify {
 	__u32	pad1; // align with 64 bits
 };
 
+static __always_inline bool policy_verdict_filter_allow(__u32 filter, __u8 dir)
+{
+	// Make dir being volatile to avoid compiler optimizing out filter (thinking
+	// it to be zero).
+	volatile __u8 d = dir;
+	return ((filter & d) > 0);
+}
+
 static __always_inline void
 send_policy_verdict_notify(struct __ctx_buff *ctx, __u32 remote_label, __u16 dst_port,
 			   __u8 proto, __u8 dir, __u8 is_ipv6, int verdict,
 			   __u8 match_type)
 {
+	if (!policy_verdict_filter_allow(POLICY_VERDICT_LOG_FILTER, dir)) {
+		return;
+	}
+
 	__u64 ctx_len = (__u64)ctx_full_len(ctx);
 	__u64 cap_len = min((__u64)TRACE_PAYLOAD_LEN, (__u64)ctx_len);
 	__u32 hash = get_hash_recalc(ctx);

diff --git a/bpf/lxc_config.h b/bpf/lxc_config.h
@@ -17,6 +17,9 @@ DEFINE_U32(SECLABEL, 0xfffff);
 DEFINE_U32(SECLABEL_NB, 0xfffff);
 #define SECLABEL_NB fetch_u32(SECLABEL_NB)
 
+DEFINE_U32(POLICY_VERDICT_LOG_FILTER, 0xffff);
+#define POLICY_VERDICT_LOG_FILTER fetch_u32(POLICY_VERDICT_LOG_FILTER)
+
 #define POLICY_MAP test_cilium_policy_65535
 
 #ifndef SKIP_DEBUG

diff --git a/pkg/datapath/config.go b/pkg/datapath/config.go
@@ -74,6 +74,9 @@ type EndpointConfiguration interface {
 	// per endpoint route installed in the host's routing table to point to
 	// the endpoint's interface
 	RequireEndpointRoute() bool
+
+	// GetPolicyVerdictLogFilter returns the PolicyVerdictLogFilter for the endpoint
+	GetPolicyVerdictLogFilter() uint32
 }
 
 // ConfigWriter is anything which writes the configuration for various datapath

diff --git a/pkg/datapath/linux/config/config.go b/pkg/datapath/linux/config/config.go
@@ -366,6 +366,7 @@ func (h *HeaderfileWriter) writeStaticData(fw io.Writer, e datapath.EndpointConf
 	secID := e.GetIdentity().Uint32()
 	fmt.Fprintf(fw, defineUint32("SECLABEL", secID))
 	fmt.Fprintf(fw, defineUint32("SECLABEL_NB", byteorder.HostToNetwork(secID).(uint32)))
+	fmt.Fprintf(fw, defineUint32("POLICY_VERDICT_LOG_FILTER", e.GetPolicyVerdictLogFilter()))
 
 	epID := uint16(e.GetID())
 	fmt.Fprintf(fw, "#define POLICY_MAP %s\n", bpf.LocalMapName(policymap.MapName, epID))

diff --git a/pkg/datapath/loader/template.go b/pkg/datapath/loader/template.go
@@ -32,8 +32,9 @@ import (
 const (
 	CallsMapName = "cilium_calls_"
 
-	templateSecurityID = identity.ReservedIdentityWorld
-	templateLxcID      = uint16(65535)
+	templateSecurityID          = identity.ReservedIdentityWorld
+	templateLxcID               = uint16(65535)
+	templatePolicyVerdictFilter = uint32(0xffff)
 )
 
 var (
@@ -117,6 +118,13 @@ func (t *templateCfg) IPv6Address() addressing.CiliumIPv6 {
 	return addressing.CiliumIPv6(templateIPv6)
 }
 
+// GetPolicyVerdictLogFilter returns an uint32 filter to ensure
+// that the filter is non-zero as per the requirements
+// described in the structure definition.
+func (t *templateCfg) GetPolicyVerdictLogFilter() uint32 {
+	return templatePolicyVerdictFilter
+}
+
 // wrap takes an endpoint configuration and optional stats tracker and wraps
 // it inside a templateCfg which hides static data from callers that wish to
 // generate header files based on the configuration, substituting it for
@@ -205,7 +213,7 @@ func elfVariableSubstitutions(ep datapath.Endpoint) map[string]uint32 {
 	identity := ep.GetIdentity().Uint32()
 	result["SECLABEL"] = identity
 	result["SECLABEL_NB"] = byteorder.HostToNetwork(identity).(uint32)
-
+	result["POLICY_VERDICT_LOG_FILTER"] = ep.GetPolicyVerdictLogFilter()
 	return result
 
 }

diff --git a/pkg/endpoint/bpf.go b/pkg/endpoint/bpf.go
@@ -1303,6 +1303,20 @@ func (e *Endpoint) RequireEndpointRoute() bool {
 	return e.DatapathConfiguration.InstallEndpointRoute
 }
 
+// GetPolicyVerdictLogFilter returns the PolicyVerdictLogFilter that would control
+// the creation of policy verdict logs. Value of VerdictLogFilter needs to be
+// consistent with how it is used in policy_verdict_filter_allow() in bpf/lib/policy_log.h
+func (e *Endpoint) GetPolicyVerdictLogFilter() uint32 {
+	var filter uint32 = 0
+	if e.desiredPolicy.IngressPolicyEnabled {
+		filter = (filter | 0x1)
+	}
+	if e.desiredPolicy.EgressPolicyEnabled {
+		filter = (filter | 0x2)
+	}
+	return filter
+}
+
 type linkCheckerFunc func(string) error
 
 // ValidateConnectorPlumbing checks whether the endpoint is correctly plumbed

diff --git a/pkg/endpoint/cache.go b/pkg/endpoint/cache.go
@@ -50,6 +50,7 @@ type epInfoCache struct {
 	requireEgressProg                      bool
 	requireRouting                         bool
 	requireEndpointRoute                   bool
+	policyVerdictLogFilter                 uint32
 	cidr4PrefixLengths, cidr6PrefixLengths []int
 	options                                *option.IntOptions
 	lxcMAC                                 mac.MAC
@@ -71,24 +72,25 @@ func (e *Endpoint) createEpInfoCache(epdir string) *epInfoCache {
 	ep := &epInfoCache{
 		revision: e.nextPolicyRevision,
 
-		epdir:                 epdir,
-		id:                    e.GetID(),
-		ifName:                e.ifName,
-		ipvlan:                e.HasIpvlanDataPath(),
-		identity:              e.GetIdentity(),
-		mac:                   e.GetNodeMAC(),
-		ipv4:                  e.IPv4Address(),
-		ipv6:                  e.IPv6Address(),
-		conntrackLocal:        e.ConntrackLocalLocked(),
-		requireARPPassthrough: e.RequireARPPassthrough(),
-		requireEgressProg:     e.RequireEgressProg(),
-		requireRouting:        e.RequireRouting(),
-		requireEndpointRoute:  e.RequireEndpointRoute(),
-		cidr4PrefixLengths:    cidr4,
-		cidr6PrefixLengths:    cidr6,
-		options:               e.Options.DeepCopy(),
-		lxcMAC:                e.mac,
-		ifIndex:               e.ifIndex,
+		epdir:                  epdir,
+		id:                     e.GetID(),
+		ifName:                 e.ifName,
+		ipvlan:                 e.HasIpvlanDataPath(),
+		identity:               e.GetIdentity(),
+		mac:                    e.GetNodeMAC(),
+		ipv4:                   e.IPv4Address(),
+		ipv6:                   e.IPv6Address(),
+		conntrackLocal:         e.ConntrackLocalLocked(),
+		requireARPPassthrough:  e.RequireARPPassthrough(),
+		requireEgressProg:      e.RequireEgressProg(),
+		requireRouting:         e.RequireRouting(),
+		requireEndpointRoute:   e.RequireEndpointRoute(),
+		policyVerdictLogFilter: e.GetPolicyVerdictLogFilter(),
+		cidr4PrefixLengths:     cidr4,
+		cidr6PrefixLengths:     cidr6,
+		options:                e.Options.DeepCopy(),
+		lxcMAC:                 e.mac,
+		ifIndex:                e.ifIndex,
 
 		endpoint: e,
 	}
@@ -187,3 +189,7 @@ func (ep *epInfoCache) RequireRouting() bool {
 func (ep *epInfoCache) RequireEndpointRoute() bool {
 	return ep.requireEndpointRoute
 }
+
+func (ep *epInfoCache) GetPolicyVerdictLogFilter() uint32 {
+	return ep.policyVerdictLogFilter
+}
diff --git a/pkg/monitor/datapath_policy.go b/pkg/monitor/datapath_policy.go
@@ -96,7 +96,7 @@ type PolicyVerdictNotify struct {
 	DstPort     uint16
 	Proto       uint8
 	Flags       uint8
-	Pad2        uint32
+	Pad1        uint32
 	// data
 }
 

diff --git a/pkg/testutils/endpoint.go b/pkg/testutils/endpoint.go
@@ -55,6 +55,7 @@ func (e *TestEndpoint) RequireARPPassthrough() bool             { return false }
 func (e *TestEndpoint) RequireEgressProg() bool                 { return false }
 func (e *TestEndpoint) RequireRouting() bool                    { return false }
 func (e *TestEndpoint) RequireEndpointRoute() bool              { return false }
+func (e *TestEndpoint) GetPolicyVerdictLogFilter() uint32       { return 0xffff }
 func (e *TestEndpoint) GetCIDRPrefixLengths() ([]int, []int)    { return nil, nil }
 func (e *TestEndpoint) GetID() uint64                           { return e.Id }
 func (e *TestEndpoint) StringID() string                        { return "42" }