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Filter out host processes by host mntns to prevent ebpf map from fill…
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neblen committed Sep 13, 2022
1 parent 2b570c3 commit 1b81911
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Showing 4 changed files with 134,196 additions and 3,810 deletions.
15 changes: 15 additions & 0 deletions internal/pkg/daemon/bpfrecorder/bpf/recorder.bpf.c
Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,7 @@
#define MAX_ENTRIES 8 * 1024
#define MAX_SYSCALLS 1024
#define MAX_COMM_LEN 64
#define MAX_MNTNS_LEN 1

char LICENSE[] SEC("license") = "Dual BSD/GPL";

Expand All @@ -24,6 +25,13 @@ struct {
__type(value, char[MAX_COMM_LEN]); // command name
} comms SEC(".maps");

struct {
__uint(type, BPF_MAP_TYPE_HASH);
__uint(max_entries, MAX_MNTNS_LEN);
__type(key, u32); // PID
__type(value, u64); // mntns ID
} system_mntns SEC(".maps");

struct {
__uint(type, BPF_MAP_TYPE_RINGBUF);
__uint(max_entries, 1 << 24);
Expand All @@ -50,6 +58,13 @@ int sys_enter(struct trace_event_raw_sys_enter * args)
if (mntns == 0) {
return 0;
}
// Filter mntns by hostmntns to exclude host processes
u32 hostPid = 1;
u64 * host_mntns;
host_mntns = bpf_map_lookup_elem(&system_mntns, &hostPid);
if (host_mntns != NULL && *host_mntns == mntns) {
return 0;
}

// Update the command name if required
char comm[MAX_COMM_LEN];
Expand Down
49 changes: 30 additions & 19 deletions internal/pkg/daemon/bpfrecorder/bpfrecorder.go
Original file line number Diff line number Diff line change
Expand Up @@ -24,16 +24,6 @@ import (
"encoding/binary"
"errors"
"fmt"
"os"
"runtime"
"sort"
"strconv"
"strings"
"sync"
"sync/atomic"
"syscall"
"time"

bpf "github.com/aquasecurity/libbpfgo"
"github.com/blang/semver/v4"
"github.com/go-logr/logr"
Expand All @@ -44,6 +34,15 @@ import (
"google.golang.org/grpc/credentials/insecure"
"k8s.io/apimachinery/pkg/util/wait"
"k8s.io/client-go/kubernetes"
"os"
"runtime"
"sort"
"strconv"
"strings"
"sync"
"sync/atomic"
"syscall"
"time"

api "sigs.k8s.io/security-profiles-operator/api/grpc/bpfrecorder"
apimetrics "sigs.k8s.io/security-profiles-operator/api/grpc/metrics"
Expand All @@ -67,6 +66,7 @@ type BpfRecorder struct {
startRequests int64
syscalls *bpf.BPFMap
comms *bpf.BPFMap
mntns *bpf.BPFMap
btfPath string
syscallNamesForIDCache *ttlcache.Cache[string, string]
containerIDCache *ttlcache.Cache[string, string]
Expand Down Expand Up @@ -423,6 +423,11 @@ func (b *BpfRecorder) load(startEventProcessor bool) (err error) {
if err != nil {
return fmt.Errorf("get comms map: %w", err)
}
b.logger.Info("Getting system_mntns map")
mntns, err := b.GetMap(module, "system_mntns")
if err != nil {
return fmt.Errorf("get mntns_map: %w", err)
}

events := make(chan []byte)
ringbuffer, err := b.InitRingBuf(module, "events", events)
Expand All @@ -433,6 +438,11 @@ func (b *BpfRecorder) load(startEventProcessor bool) (err error) {

b.syscalls = syscalls
b.comms = comms
b.mntns = mntns

// Update mntns to system_mntns
b.updateSystemMntns()

if startEventProcessor {
go b.processEvents(events)
}
Expand Down Expand Up @@ -564,6 +574,16 @@ func (b *BpfRecorder) processEvents(events chan []byte) {
}
}

func (b *BpfRecorder) updateSystemMntns() {
mntnsByte := make([]byte, 8)
binary.LittleEndian.PutUint64(mntnsByte, b.systemMountNamespace)
var hostPid uint32 = 1
err := b.UpdateValue(b.mntns, hostPid, mntnsByte)
if err != nil {
b.logger.Error(err, "update system_mntns map failed")
}
}

func (b *BpfRecorder) handleEvent(event []byte) {
// Newly arrived PIDs
const eventLen = 16
Expand All @@ -575,15 +595,6 @@ func (b *BpfRecorder) handleEvent(event []byte) {
pid := binary.LittleEndian.Uint32(event)
mntns := binary.LittleEndian.Uint64(event[8:])

// Filter out non-containers
if mntns == b.systemMountNamespace {
b.logger.V(config.VerboseLevel).Info(
"Skipping PID, because it's on the system mount namespace",
"pid", pid, "mntns", mntns,
)
return
}

// Blocking from syscall retrieval when PIDs are currently being analyzed
b.pidLock.Lock()
defer b.pidLock.Unlock()
Expand Down
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