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ebpf: add a new required dependency field. #1707

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ebpf: add a new required dependency field. #1707

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7 changes: 4 additions & 3 deletions pkg/ebpf/events_definitions.go
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Original file line number Diff line number Diff line change
Expand Up @@ -25,6 +25,7 @@ type probe struct {
type eventDependency struct {
eventID int32
shouldSubmit bool
required bool
}

type dependencies struct {
Expand Down Expand Up @@ -6202,7 +6203,7 @@ var EventsDefinitions = map[int32]EventDefinition{
Name: "container_create",
Probes: []probe{},
Dependencies: dependencies{
events: []eventDependency{{eventID: CgroupMkdirEventID, shouldSubmit: true}},
events: []eventDependency{{eventID: CgroupMkdirEventID, shouldSubmit: true, required: true}},
},
Sets: []string{},
Params: []trace.ArgMeta{
Expand All @@ -6216,7 +6217,7 @@ var EventsDefinitions = map[int32]EventDefinition{
Name: "container_remove",
Probes: []probe{},
Dependencies: dependencies{
events: []eventDependency{{eventID: CgroupRmdirEventID, shouldSubmit: true}},
events: []eventDependency{{eventID: CgroupRmdirEventID, shouldSubmit: true, required: true}},
},
Sets: []string{},
Params: []trace.ArgMeta{
Expand Down Expand Up @@ -6314,7 +6315,7 @@ var EventsDefinitions = map[int32]EventDefinition{
ID32Bit: sys32undefined,
Name: "detect_hooked_syscalls",
Dependencies: dependencies{
events: []eventDependency{{eventID: FinitModuleEventID}, {eventID: PrintSyscallTableEventID}, {eventID: InitModuleEventID}},
events: []eventDependency{{eventID: FinitModuleEventID, required: true}, {eventID: PrintSyscallTableEventID, required: true}, {eventID: InitModuleEventID, required: true}},
},
Sets: []string{},
Params: []trace.ArgMeta{
Expand Down
92 changes: 53 additions & 39 deletions pkg/ebpf/tracee.go
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Original file line number Diff line number Diff line change
Expand Up @@ -163,8 +163,9 @@ type fileExecInfo struct {
}

type eventConfig struct {
submit bool // event should be submitted to userspace
emit bool // event should be emitted to the user
required bool // event must be attached for tracee to initialize
submit bool // event should be submitted to userspace
emit bool // event should be emitted to the user
}

// Tracee traces system calls and system events using eBPF
Expand Down Expand Up @@ -217,6 +218,9 @@ func (t *Tracee) handleEventsDependencies(e int32, initReq *RequiredInitValues)
if dependentEvent.shouldSubmit {
ec.submit = true
}
if dependentEvent.required {
ec.required = true
}
t.events[dependentEvent.eventID] = ec
}
}
Expand Down Expand Up @@ -255,41 +259,8 @@ func New(cfg Config) (*Tracee, error) {

t.events = make(map[int32]eventConfig, len(cfg.Filter.EventsToTrace))

// Set essential events
t.events[SysEnterEventID] = eventConfig{}
t.events[SysExitEventID] = eventConfig{}
t.events[SchedProcessForkEventID] = eventConfig{}
t.events[SchedProcessExecEventID] = eventConfig{}
t.events[SchedProcessExitEventID] = eventConfig{}
t.events[CgroupMkdirEventID] = eventConfig{submit: true}
t.events[CgroupRmdirEventID] = eventConfig{submit: true}

// Set events used to capture data
if t.config.Capture.Exec {
t.events[SchedProcessExecEventID] = eventConfig{submit: true}
}
if t.config.Capture.FileWrite {
t.events[VfsWriteEventID] = eventConfig{}
t.events[VfsWritevEventID] = eventConfig{}
t.events[__KernelWriteEventID] = eventConfig{}
}
if t.config.Capture.Module {
t.events[SecurityPostReadFileEventID] = eventConfig{}
t.events[InitModuleEventID] = eventConfig{}
}
if t.config.Capture.Mem {
t.events[MmapEventID] = eventConfig{}
t.events[MprotectEventID] = eventConfig{}
t.events[MemProtAlertEventID] = eventConfig{}
}
if t.config.Capture.NetIfaces != nil || len(t.config.Filter.NetFilter.InterfacesToTrace) > 0 || cfg.Debug {
t.events[SecuritySocketBindEventID] = eventConfig{}
}

// Events chosen by the user
for _, e := range t.config.Filter.EventsToTrace {
t.events[e] = eventConfig{submit: true, emit: true}
}
// Setup tracee's required events
t.initRequiredEvents()

initReq := RequiredInitValues{}
// Handles all essential events dependencies
Expand Down Expand Up @@ -404,6 +375,46 @@ func New(cfg Config) (*Tracee, error) {
return t, nil
}

// Initialize all events required by tracee to function
// Required events which fail to attach will fail loading tracee
func (t *Tracee) initRequiredEvents() {
// Set required events
t.events[SysEnterEventID] = eventConfig{required: true}
t.events[SysExitEventID] = eventConfig{required: true}
t.events[SchedProcessForkEventID] = eventConfig{required: true}
t.events[SchedProcessExecEventID] = eventConfig{required: true}
t.events[SchedProcessExitEventID] = eventConfig{required: true}
t.events[CgroupMkdirEventID] = eventConfig{required: true, submit: true}
t.events[CgroupRmdirEventID] = eventConfig{required: true, submit: true}

// Set events used to capture data
if t.config.Capture.Exec {
t.events[SchedProcessExecEventID] = eventConfig{required: true, submit: true}
}
if t.config.Capture.FileWrite {
t.events[VfsWriteEventID] = eventConfig{required: true}
t.events[VfsWritevEventID] = eventConfig{required: true}
t.events[__KernelWriteEventID] = eventConfig{required: true}
}
if t.config.Capture.Module {
t.events[SecurityPostReadFileEventID] = eventConfig{required: true}
t.events[InitModuleEventID] = eventConfig{required: true}
}
if t.config.Capture.Mem {
t.events[MmapEventID] = eventConfig{required: true}
t.events[MprotectEventID] = eventConfig{required: true}
t.events[MemProtAlertEventID] = eventConfig{required: true}
}
if t.config.Capture.NetIfaces != nil || len(t.config.Filter.NetFilter.InterfacesToTrace) > 0 || t.config.Debug {
t.events[SecuritySocketBindEventID] = eventConfig{required: true}
}

// Events chosen by the user
for _, e := range t.config.Filter.EventsToTrace {
t.events[e] = eventConfig{required: true, submit: true, emit: true}
}
}

// Initialize tail calls program array
func (t *Tracee) initTailCall(tailNum uint32, mapName string, progName string) error {

Expand Down Expand Up @@ -1053,7 +1064,7 @@ func (t *Tracee) initBPF() error {
}
}

for e := range t.events {
for e, eventConfig := range t.events {
event, ok := EventsDefinitions[e]
if !ok {
continue
Expand Down Expand Up @@ -1084,7 +1095,10 @@ func (t *Tracee) initBPF() error {
_, err = prog.AttachRawTracepoint(tpEvent)
}
if err != nil {
return fmt.Errorf("error attaching event %s: %v", probe.event, err)
if eventConfig.required {
return fmt.Errorf("error attaching required event %s: %v", probe.event, err)
}
t.handleError(fmt.Errorf("error attaching event %s: %v. event was marked as unrequired and tracee will continue to load", probe.event, err))
}
}
}
Expand Down