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Handle overlaps in except and allow CIDRs #344

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f74d533
changes for except cidrs
Pavani-Panakanti Dec 5, 2024
f6cc88b
Update logs
Pavani-Panakanti Dec 6, 2024
0e035bd
update denyall logic
Pavani-Panakanti Dec 6, 2024
645fc4f
update unit tests
Pavani-Panakanti Dec 6, 2024
e079bed
Merge branch 'main' into fix-handling-except
Pavani-Panakanti May 8, 2025
9a3650b
add description to functions
Pavani-Panakanti May 11, 2025
70f1c6f
Merge branch 'main' into fix-handling-except
Pavani-Panakanti Jun 2, 2025
2fb6ca5
Merge branch 'main' into fix-handling-except
Pavani-Panakanti Jun 4, 2025
3290f1c
merge main
Pavani-Panakanti Jun 19, 2025
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22 changes: 18 additions & 4 deletions pkg/ebpf/c/tc.v4egress.bpf.c
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Original file line number Diff line number Diff line change
Expand Up @@ -111,10 +111,24 @@ static inline int evaluateByLookUp(struct keystruct trie_key, struct conntrack_k
bpf_ringbuf_output(&policy_events, &evt, sizeof(evt), 0);
return BPF_DROP;
}

if ((trie_val->protocol == ANY_IP_PROTOCOL) || (trie_val->protocol == ip->protocol &&
((trie_val->start_port == ANY_PORT) || (l4_dst_port == trie_val->start_port) ||
(l4_dst_port > trie_val->start_port && l4_dst_port <= trie_val->end_port)))) {

// 1. ANY_IP_PROTOCOL:
// - If the rule specifies ANY_IP_PROTOCOL (i.e., applies to all L4 protocols),
// - Then match if:
// - start_port is ANY_PORT → rule applies to all ports
// - OR l4_dst_port is exactly the start_port
// - OR l4_dst_port falls within the inclusive [start_port, end_port] range
//
// 2. Specific Protocol Match:
// - If trie_val->protocol matches the packet's IP protocol (e.g., TCP or UDP),
// - Then apply the same port match logic as above.

if ((trie_val->protocol == ANY_IP_PROTOCOL &&
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They are really complicate if check... Any chance we can take them out into a func? I think there is only one small different on ip-> for v4 and v6.

((trie_val->start_port == ANY_PORT) || (l4_dst_port == trie_val->start_port) ||
(l4_dst_port > trie_val->start_port && l4_dst_port <= trie_val->end_port))) ||
(trie_val->protocol == ip->protocol &&
((trie_val->start_port == ANY_PORT) || (l4_dst_port == trie_val->start_port) ||
(l4_dst_port > trie_val->start_port && l4_dst_port <= trie_val->end_port)))) {
//Inject in to conntrack map
struct conntrack_value new_flow_val = {};
if (pst->state == DEFAULT_ALLOW) {
Expand Down
19 changes: 16 additions & 3 deletions pkg/ebpf/c/tc.v4ingress.bpf.c
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Original file line number Diff line number Diff line change
Expand Up @@ -112,9 +112,22 @@ static inline int evaluateByLookUp(struct keystruct trie_key, struct conntrack_k
return BPF_DROP;
}

if ((trie_val->protocol == ANY_IP_PROTOCOL) || (trie_val->protocol == ip->protocol &&
((trie_val->start_port == ANY_PORT) || (l4_dst_port == trie_val->start_port) ||
(l4_dst_port > trie_val->start_port && l4_dst_port <= trie_val->end_port)))) {
// 1. ANY_IP_PROTOCOL:
// - If the rule specifies ANY_IP_PROTOCOL (i.e., applies to all L4 protocols),
// - Then match if:
// - start_port is ANY_PORT → rule applies to all ports
// - OR l4_dst_port is exactly the start_port
// - OR l4_dst_port falls within the inclusive [start_port, end_port] range
//
// 2. Specific Protocol Match:
// - If trie_val->protocol matches the packet's IP protocol (e.g., TCP or UDP),
// - Then apply the same port match logic as above.
if ((trie_val->protocol == ANY_IP_PROTOCOL &&
((trie_val->start_port == ANY_PORT) || (l4_dst_port == trie_val->start_port) ||
(l4_dst_port > trie_val->start_port && l4_dst_port <= trie_val->end_port))) ||
(trie_val->protocol == ip->protocol &&
((trie_val->start_port == ANY_PORT) || (l4_dst_port == trie_val->start_port) ||
(l4_dst_port > trie_val->start_port && l4_dst_port <= trie_val->end_port)))) {
//Inject in to conntrack map
struct conntrack_value new_flow_val = {};
if (pst->state == DEFAULT_ALLOW) {
Expand Down
19 changes: 16 additions & 3 deletions pkg/ebpf/c/tc.v6egress.bpf.c
View file
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Original file line number Diff line number Diff line change
Expand Up @@ -113,9 +113,22 @@ static inline int evaluateByLookUp(struct keystruct trie_key, struct conntrack_k
return BPF_DROP;
}

if ((trie_val->protocol == ANY_IP_PROTOCOL) || (trie_val->protocol == ip->nexthdr &&
((trie_val->start_port == ANY_PORT) || (l4_dst_port == trie_val->start_port) ||
(l4_dst_port > trie_val->start_port && l4_dst_port <= trie_val->end_port)))) {
// 1. ANY_IP_PROTOCOL:
// - If the rule specifies ANY_IP_PROTOCOL (i.e., applies to all L4 protocols),
// - Then match if:
// - start_port is ANY_PORT → rule applies to all ports
// - OR l4_dst_port is exactly the start_port
// - OR l4_dst_port falls within the inclusive [start_port, end_port] range
//
// 2. Specific Protocol Match:
// - If trie_val->protocol matches the packet's IP protocol (e.g., TCP or UDP),
// - Then apply the same port match logic as above.
if ((trie_val->protocol == ANY_IP_PROTOCOL &&
((trie_val->start_port == ANY_PORT) || (l4_dst_port == trie_val->start_port) ||
(l4_dst_port > trie_val->start_port && l4_dst_port <= trie_val->end_port))) ||
(trie_val->protocol == ip->nexthdr &&
((trie_val->start_port == ANY_PORT) || (l4_dst_port == trie_val->start_port) ||
(l4_dst_port > trie_val->start_port && l4_dst_port <= trie_val->end_port)))) {
//Inject in to conntrack map
struct conntrack_value new_flow_val = {};
if (pst->state == DEFAULT_ALLOW) {
Expand Down
19 changes: 16 additions & 3 deletions pkg/ebpf/c/tc.v6ingress.bpf.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -115,9 +115,22 @@ static inline int evaluateByLookUp(struct keystruct trie_key, struct conntrack_k
return BPF_DROP;
}

if ((trie_val->protocol == ANY_IP_PROTOCOL) || (trie_val->protocol == ip->nexthdr &&
((trie_val->start_port == ANY_PORT) || (l4_dst_port == trie_val->start_port) ||
(l4_dst_port > trie_val->start_port && l4_dst_port <= trie_val->end_port)))) {
// 1. ANY_IP_PROTOCOL:
// - If the rule specifies ANY_IP_PROTOCOL (i.e., applies to all L4 protocols),
// - Then match if:
// - start_port is ANY_PORT → rule applies to all ports
// - OR l4_dst_port is exactly the start_port
// - OR l4_dst_port falls within the inclusive [start_port, end_port] range
//
// 2. Specific Protocol Match:
// - If trie_val->protocol matches the packet's IP protocol (e.g., TCP or UDP),
// - Then apply the same port match logic as above.
if ((trie_val->protocol == ANY_IP_PROTOCOL &&
((trie_val->start_port == ANY_PORT) || (l4_dst_port == trie_val->start_port) ||
(l4_dst_port > trie_val->start_port && l4_dst_port <= trie_val->end_port))) ||
(trie_val->protocol == ip->nexthdr &&
((trie_val->start_port == ANY_PORT) || (l4_dst_port == trie_val->start_port) ||
(l4_dst_port > trie_val->start_port && l4_dst_port <= trie_val->end_port)))) {
//Inject in to conntrack map
struct conntrack_value new_flow_val = {};
if (pst->state == DEFAULT_ALLOW) {
Expand Down
193 changes: 97 additions & 96 deletions pkg/fwruleprocessor/fw_rule_processor.go
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Original file line number Diff line number Diff line change
Expand Up @@ -17,7 +17,10 @@ func log() logger.Logger {
return logger.Get()
}

var CATCH_ALL_PROTOCOL corev1.Protocol = "ANY_IP_PROTOCOL"
var (
CATCH_ALL_PROTOCOL corev1.Protocol = "ANY_IP_PROTOCOL"
DENY_ALL_PROTOCOL corev1.Protocol = "RESERVED_IP_PROTOCOL_NUMBER"
)

type EbpfFirewallRules struct {
IPCidr v1alpha1.NetworkAddress
Expand All @@ -42,13 +45,31 @@ func NewFirewallRuleProcessor(nodeIP string, hostMask string, enableIPv6 bool) *
return fwrp
}

// computeMapEntriesFromEndpointRules generates a map of IP prefix keys to encoded L4 rules that will
// be used to update ebpf maps
//
// How it works:
// 1. A default allow-all entry is added for the node IP to ensure local node traffic is always permitted.
// 2. The list of firewall rules is sorted by prefix length in ascending order. This is crucial for
// handling overlapping CIDRs because longest-prefix matches win in LPM TRIE.
// 3. Each rule is normalized:
// - Ensures all entries contain a /mask (using hostMask if omitted).
// - Filters out IPv4 rules in IPv6 clusters and vice versa.
// - For rules without any L4 port info, a catch-all rule is inserted to match all traffic.
// 4. For any rule whose CIDR is more specific (e.g., /24) and falls within a broader one (e.g., /16),
// we check existing rules in the map to see if it matches a prior CIDR. If it does and is not part of
// that CIDR's "except" list, we inherit the broader rule's ports into the current one.
// This ensures that the specific CIDR behaves consistently with the broader scope's intent.
// 5. We then handle all `except` CIDRs at the end.
// - If not already in the map, each `except` CIDR is added explicitly with a deny-all L4 entry.
// - This ensures specific excluded IP ranges override broader allow rules correctly in the LPM match tree.
// 6. Finally, all CIDRs are encoded into trie keys and their corresponding merged/derived L4 info is encoded
// into the values, forming the output map.

func (f *FirewallRuleProcessor) ComputeMapEntriesFromEndpointRules(firewallRules []EbpfFirewallRules) (map[string][]byte, error) {

firewallMap := make(map[string][]byte)
ipCIDRs := make(map[string][]v1alpha1.Port)
nonHostCIDRs := make(map[string][]v1alpha1.Port)
isCatchAllIPEntryPresent, allowAll := false, false
var catchAllIPPorts []v1alpha1.Port
cidrsMap := make(map[string]EbpfFirewallRules)

//Traffic from the local node should always be allowed. Add NodeIP by default to map entries.
_, mapKey, _ := net.ParseCIDR(f.nodeIP + f.hostMask)
Expand All @@ -59,16 +80,6 @@ func (f *FirewallRuleProcessor) ComputeMapEntriesFromEndpointRules(firewallRules
//Sort the rules
sortFirewallRulesByPrefixLength(firewallRules, f.hostMask)

//Check and aggregate L4 Port Info for Catch All Entries.
catchAllIPPorts, isCatchAllIPEntryPresent, allowAll = f.checkAndDeriveCatchAllIPPorts(firewallRules)
if isCatchAllIPEntryPresent {
//Add the Catch All IP entry
_, mapKey, _ := net.ParseCIDR("0.0.0.0/0")
key := utils.ComputeTrieKey(*mapKey, f.enableIPv6)
value := utils.ComputeTrieValue(catchAllIPPorts, allowAll, false)
firewallMap[string(key)] = value
}

for _, firewallRule := range firewallRules {
var cidrL4Info []v1alpha1.Port

Expand All @@ -90,94 +101,62 @@ func (f *FirewallRuleProcessor) ComputeMapEntriesFromEndpointRules(firewallRules
continue
}

if !utils.IsCatchAllIPEntry(string(firewallRule.IPCidr)) {
if len(firewallRule.L4Info) == 0 {
addCatchAllL4Entry(&firewallRule)
}
if utils.IsNonHostCIDR(string(firewallRule.IPCidr)) {
existingL4Info, ok := nonHostCIDRs[string(firewallRule.IPCidr)]
if ok {
firewallRule.L4Info = append(firewallRule.L4Info, existingL4Info...)
} else {
// Check if the /m entry is part of any /n CIDRs that we've encountered so far
// If found, we need to include the port and protocol combination against the current entry as well since
// we use LPM TRIE map and the /m will always win out.
cidrL4Info = checkAndDeriveL4InfoFromAnyMatchingCIDRs(string(firewallRule.IPCidr), nonHostCIDRs)
if len(cidrL4Info) > 0 {
firewallRule.L4Info = append(firewallRule.L4Info, cidrL4Info...)
}
}
nonHostCIDRs[string(firewallRule.IPCidr)] = firewallRule.L4Info
} else {
if existingL4Info, ok := ipCIDRs[string(firewallRule.IPCidr)]; ok {
firewallRule.L4Info = append(firewallRule.L4Info, existingL4Info...)
}
// Check if the /32 entry is part of any non host CIDRs that we've encountered so far
// If found, we need to include the port and protocol combination against the current entry as well since
// we use LPM TRIE map and the /32 will always win out.
cidrL4Info = checkAndDeriveL4InfoFromAnyMatchingCIDRs(string(firewallRule.IPCidr), nonHostCIDRs)
if len(cidrL4Info) > 0 {
firewallRule.L4Info = append(firewallRule.L4Info, cidrL4Info...)
}
ipCIDRs[string(firewallRule.IPCidr)] = firewallRule.L4Info
}
//Include port and protocol combination paired with catch all entries
firewallRule.L4Info = append(firewallRule.L4Info, catchAllIPPorts...)

log().Infof("Updating Map with IP Key: %s", string(firewallRule.IPCidr))
_, firewallMapKey, _ := net.ParseCIDR(string(firewallRule.IPCidr))
// Key format: Prefix length (4 bytes) followed by 4/16byte IP address
firewallKey := utils.ComputeTrieKey(*firewallMapKey, f.enableIPv6)

if len(firewallRule.L4Info) != 0 {
mergedL4Info := mergeDuplicateL4Info(firewallRule.L4Info)
firewallRule.L4Info = mergedL4Info
// If no L4 specified add catch all entry
if len(firewallRule.L4Info) == 0 {
log().Debugf("No L4 specified. Add Catch all entry CIDR: %s", string(firewallRule.IPCidr))
addCatchAllL4Entry(&firewallRule)
log().Debugf("Total L4 entries count: %d", len(firewallRule.L4Info))
}

if existingFirewallRuleInfo, ok := cidrsMap[string(firewallRule.IPCidr)]; ok {
firewallRule.L4Info = append(firewallRule.L4Info, existingFirewallRuleInfo.L4Info...)
firewallRule.Except = append(firewallRule.Except, existingFirewallRuleInfo.Except...)
} else {
// Check if the /m entry is part of any /n CIDRs that we've encountered so far
// If found, we need to include the port and protocol combination against the current entry as well since
// we use LPM TRIE map and the /m will always win out.
cidrL4Info = checkAndDeriveL4InfoFromAnyMatchingCIDRs(string(firewallRule.IPCidr), cidrsMap)
if len(cidrL4Info) > 0 {
firewallRule.L4Info = append(firewallRule.L4Info, cidrL4Info...)
}
firewallValue := utils.ComputeTrieValue(firewallRule.L4Info, allowAll, false)
firewallMap[string(firewallKey)] = firewallValue
}
cidrsMap[string(firewallRule.IPCidr)] = firewallRule
}

// Go through except CIDRs and append DENY all rule to the L4 info
for _, firewallRule := range firewallRules {
if firewallRule.Except != nil {
for _, exceptCIDR := range firewallRule.Except {
_, mapKey, _ := net.ParseCIDR(string(exceptCIDR))
key := utils.ComputeTrieKey(*mapKey, f.enableIPv6)
log().Infof("Parsed Except CIDR IP Key: %s", mapKey.String())
if len(firewallRule.L4Info) != 0 {
mergedL4Info := mergeDuplicateL4Info(firewallRule.L4Info)
firewallRule.L4Info = mergedL4Info
for _, exceptCidr := range firewallRule.Except {
if _, ok := cidrsMap[string(exceptCidr)]; !ok {
exceptFirewall := EbpfFirewallRules{
IPCidr: exceptCidr,
Except: []v1alpha1.NetworkAddress{},
L4Info: []v1alpha1.Port{},
}
addDenyAllL4Entry(&exceptFirewall)
cidrsMap[string(exceptCidr)] = exceptFirewall
}
value := utils.ComputeTrieValue(firewallRule.L4Info, false, true)
firewallMap[string(key)] = value
log().Debugf("Parsed Except CIDR:", string(exceptCidr))
}
}
}

return firewallMap, nil
}
for key, value := range cidrsMap {
log().Infof("Updating Map with IP Key: %s", string(key))
_, firewallMapKey, _ := net.ParseCIDR(string(key))
// Key format: Prefix length (4 bytes) followed by 4/16byte IP address
firewallKey := utils.ComputeTrieKey(*firewallMapKey, f.enableIPv6)

if len(value.L4Info) != 0 {
mergedL4Info := mergeDuplicateL4Info(value.L4Info)
value.L4Info = mergedL4Info

func (f *FirewallRuleProcessor) checkAndDeriveCatchAllIPPorts(firewallRules []EbpfFirewallRules) ([]v1alpha1.Port, bool, bool) {
var catchAllL4Info []v1alpha1.Port
isCatchAllIPEntryPresent := false
allowAllPortAndProtocols := false
for _, firewallRule := range firewallRules {
if !strings.Contains(string(firewallRule.IPCidr), "/") {
firewallRule.IPCidr += v1alpha1.NetworkAddress(f.hostMask)
}
if !f.enableIPv6 && strings.Contains(string(firewallRule.IPCidr), "::") {
log().Debug("IPv6 catch all entry in IPv4 mode - skip ")
continue
}
if utils.IsCatchAllIPEntry(string(firewallRule.IPCidr)) {
catchAllL4Info = append(catchAllL4Info, firewallRule.L4Info...)
isCatchAllIPEntryPresent = true
if len(firewallRule.L4Info) == 0 {
//All ports and protocols
allowAllPortAndProtocols = true
}
}
firewallValue := utils.ComputeTrieValue(value.L4Info, false, false)
firewallMap[string(firewallKey)] = firewallValue
}
log().Debugf("Total L4 entry count for catch all entry: count: %d", len(catchAllL4Info))
return catchAllL4Info, isCatchAllIPEntryPresent, allowAllPortAndProtocols

return firewallMap, nil
}

// sorting Firewall Rules in Ascending Order of Prefix length
Expand Down Expand Up @@ -212,16 +191,38 @@ func addCatchAllL4Entry(firewallRule *EbpfFirewallRules) {
firewallRule.L4Info = append(firewallRule.L4Info, catchAllL4Entry)
}

func addDenyAllL4Entry(firewallRule *EbpfFirewallRules) {
denyAllL4Entry := v1alpha1.Port{
Protocol: &DENY_ALL_PROTOCOL,
}
firewallRule.L4Info = append(firewallRule.L4Info, denyAllL4Entry)
}

func checkAndDeriveL4InfoFromAnyMatchingCIDRs(firewallRule string,
nonHostCIDRs map[string][]v1alpha1.Port) []v1alpha1.Port {
cidrsMap map[string]EbpfFirewallRules) []v1alpha1.Port {
var matchingCIDRL4Info []v1alpha1.Port

_, ipToCheck, _ := net.ParseCIDR(firewallRule)
for nonHostCIDR, l4Info := range nonHostCIDRs {
_, cidrEntry, _ := net.ParseCIDR(nonHostCIDR)
for cidr, cidrFirewallInfo := range cidrsMap {
if !utils.IsNonHostCIDR(cidr) {
continue
}
_, cidrEntry, _ := net.ParseCIDR(cidr)
if cidrEntry.Contains(ipToCheck.IP) {
log().Debugf("Found a CIDR match for IP: %s in CIDR %s ", firewallRule, nonHostCIDR)
matchingCIDRL4Info = append(matchingCIDRL4Info, l4Info...)
log().Debugf("Found CIDR match or IP: %s in CIDR: %s", firewallRule, cidr)
// If CIDR contains IP, check if it is part of any except block under CIDR. If yes, do not include cidrL4Info
foundInExcept := false
for _, except := range cidrFirewallInfo.Except {
_, exceptEntry, _ := net.ParseCIDR(string(except))
if exceptEntry.Contains(ipToCheck.IP) {
foundInExcept = true
log().Debugf("Found IP: %s in except block %s of CIDR %s. Skipping CIDR match", firewallRule, string(except), cidr)
break
}
}
if !foundInExcept {
matchingCIDRL4Info = append(matchingCIDRL4Info, cidrFirewallInfo.L4Info...)
}
}
}
return matchingCIDRL4Info
Expand Down
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