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[WIP] feat: extend string data filtering for other events #4470

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[WIP] feat: extend string data filtering for other events #4470

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f8f0af6
feat: allow different field names
rscampos Jan 31, 2025
41b8fa0
feat: extend string data filtering for other events
rscampos Jan 31, 2025
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1 change: 1 addition & 0 deletions pkg/ebpf/c/common/context.h
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -259,6 +259,7 @@ statfunc bool reset_event(event_data_t *event, u32 event_id)
event->config.field_types = event_config->field_types;
event->config.submit_for_policies = event_config->submit_for_policies;
event->context.matched_policies = event_config->submit_for_policies;
event->config.data_filter = event_config->data_filter;

return true;
}
Expand Down
77 changes: 77 additions & 0 deletions pkg/ebpf/c/tracee.bpf.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -387,6 +387,9 @@ int syscall__execve_enter(void *ctx)
&p.event->args_buf, (const char *const *) sys->args.args[2] /*envp*/, 2);
}

if (!evaluate_data_filters(&p, 0))
return 0;

return events_perf_submit(&p, 0);
}

Expand Down Expand Up @@ -417,6 +420,9 @@ int syscall__execve_exit(void *ctx)
&p.event->args_buf, (const char *const *) sys->args.args[2] /*envp*/, 2);
}

if (!evaluate_data_filters(&p, 0))
return 0;

return events_perf_submit(&p, sys->ret);
}

Expand Down Expand Up @@ -447,6 +453,9 @@ int syscall__execveat_enter(void *ctx)
}
save_to_submit_buf(&p.event->args_buf, (void *) &sys->args.args[4] /*flags*/, sizeof(int), 4);

if (!evaluate_data_filters(&p, 1))
return 0;

return events_perf_submit(&p, 0);
}

Expand Down Expand Up @@ -479,6 +488,9 @@ int syscall__execveat_exit(void *ctx)
}
save_to_submit_buf(&p.event->args_buf, (void *) &sys->args.args[4] /*flags*/, sizeof(int), 4);

if (!evaluate_data_filters(&p, 1))
return 0;

return events_perf_submit(&p, sys->ret);
}

Expand Down Expand Up @@ -1714,6 +1726,9 @@ int BPF_KPROBE(trace_call_usermodehelper)
save_str_arr_to_buf(&p.event->args_buf, (const char *const *) envp, 2);
save_to_submit_buf(&p.event->args_buf, (void *) &wait, sizeof(int), 3);

if (!evaluate_data_filters(&p, 0))
return 0;

return events_perf_submit(&p, 0);
}

Expand Down Expand Up @@ -2272,6 +2287,9 @@ int BPF_KPROBE(trace_security_bprm_check)
if (p.config->options & OPT_EXEC_ENV)
save_str_arr_to_buf(&p.event->args_buf, envp, 4);

if (!evaluate_data_filters(&p, 0))
return 0;

return events_perf_submit(&p, 0);
}

Expand Down Expand Up @@ -2347,6 +2365,9 @@ int BPF_KPROBE(trace_security_sb_mount)
save_str_to_buf(&p.event->args_buf, (void *) type, 2);
save_to_submit_buf(&p.event->args_buf, &flags, sizeof(unsigned long), 3);

if (!evaluate_data_filters(&p, 1))
return 0;

return events_perf_submit(&p, 0);
}

Expand Down Expand Up @@ -2381,6 +2402,9 @@ int BPF_KPROBE(trace_security_inode_unlink)
save_to_submit_buf(&p.event->args_buf, &unlinked_file_id.device, sizeof(dev_t), 2);
save_to_submit_buf(&p.event->args_buf, &unlinked_file_id.ctime, sizeof(u64), 3);

if (!evaluate_data_filters(&p, 0))
return 0;

return events_perf_submit(&p, 0);
}

Expand Down Expand Up @@ -2580,6 +2604,9 @@ int BPF_KPROBE(trace_security_inode_symlink)
save_str_to_buf(&p.event->args_buf, dentry_path, 0);
save_str_to_buf(&p.event->args_buf, (void *) old_name, 1);

if (!evaluate_data_filters(&p, 0))
return 0;

return events_perf_submit(&p, 0);
}

Expand Down Expand Up @@ -3610,6 +3637,9 @@ int BPF_KPROBE(trace_ret_do_mmap)
save_to_submit_buf(&p.event->args_buf, &prot, sizeof(unsigned long), 8);
save_to_submit_buf(&p.event->args_buf, &mmap_flags, sizeof(unsigned long), 9);

if (!evaluate_data_filters(&p, 1))
return 0;

return events_perf_submit(&p, 0);
}

Expand Down Expand Up @@ -3643,6 +3673,9 @@ int BPF_KPROBE(trace_security_mmap_file)
save_to_submit_buf(&p.event->args_buf, &inode_nr, sizeof(unsigned long), 3);
save_to_submit_buf(&p.event->args_buf, &ctime, sizeof(u64), 4);

if (!evaluate_data_filters(&p, 0))
return 0;

events_perf_submit(&p, 0);
}

Expand Down Expand Up @@ -3711,6 +3744,9 @@ int BPF_KPROBE(trace_security_file_mprotect)
save_to_submit_buf(&p.event->args_buf, &pkey, sizeof(int), 6);
}

if (!evaluate_data_filters(&p, 0))
return 0;

events_perf_submit(&p, 0);
}

Expand Down Expand Up @@ -3953,6 +3989,9 @@ int BPF_KPROBE(trace_security_bpf_map)
// 2nd argument == map_name (const char *)
save_str_to_buf(&p.event->args_buf, (void *) __builtin_preserve_access_index(&map->name), 1);

if (!evaluate_data_filters(&p, 1))
return 0;

return events_perf_submit(&p, 0);
}

Expand Down Expand Up @@ -4008,6 +4047,9 @@ int BPF_KPROBE(trace_security_bpf_prog)
save_to_submit_buf(&p.event->args_buf, &prog_id, sizeof(u32), 3);
save_to_submit_buf(&p.event->args_buf, &is_load, sizeof(bool), 4);

if (!evaluate_data_filters(&p, 1))
return 0;

events_perf_submit(&p, 0);

return 0;
Expand Down Expand Up @@ -4149,6 +4191,9 @@ int BPF_KPROBE(trace_security_kernel_read_file)
save_to_submit_buf(&p.event->args_buf, &type_id, sizeof(int), 3);
save_to_submit_buf(&p.event->args_buf, &ctime, sizeof(u64), 4);

if (!evaluate_data_filters(&p, 0))
return 0;

return events_perf_submit(&p, 0);
}

Expand All @@ -4173,6 +4218,10 @@ int BPF_KPROBE(trace_security_kernel_post_read_file)
save_str_to_buf(&p.event->args_buf, file_path, 0);
save_to_submit_buf(&p.event->args_buf, &size, sizeof(loff_t), 1);
save_to_submit_buf(&p.event->args_buf, &type_id, sizeof(int), 2);

if (!evaluate_data_filters(&p, 0))
return 0;

events_perf_submit(&p, 0);
}

Expand Down Expand Up @@ -4221,6 +4270,9 @@ int BPF_KPROBE(trace_security_inode_mknod)
save_to_submit_buf(&p.event->args_buf, &mode, sizeof(unsigned short), 1);
save_to_submit_buf(&p.event->args_buf, &dev, sizeof(dev_t), 2);

if (!evaluate_data_filters(&p, 0))
return 0;

return events_perf_submit(&p, 0);
}

Expand Down Expand Up @@ -4463,6 +4515,9 @@ int tracepoint__module__module_load(struct bpf_raw_tracepoint_args *ctx)
save_str_to_buf(&p.event->args_buf, (void *) version, 1);
save_str_to_buf(&p.event->args_buf, (void *) srcversion, 2);

if (!evaluate_data_filters(&p, 3))
return 0;

return events_perf_submit(&p, 0);
}

Expand Down Expand Up @@ -4571,6 +4626,10 @@ int BPF_KPROBE(trace_load_elf_phdrs)
save_str_to_buf(&p.event->args_buf, (void *) elf_pathname, 0);
save_to_submit_buf(&p.event->args_buf, &proc_info->interpreter.id.device, sizeof(dev_t), 1);
save_to_submit_buf(&p.event->args_buf, &proc_info->interpreter.id.inode, sizeof(unsigned long), 2);

if (!evaluate_data_filters(&p, 0))
return 0;

events_perf_submit(&p, 0);

return 0;
Expand Down Expand Up @@ -4678,6 +4737,9 @@ int BPF_KPROBE(trace_security_inode_rename)
void *new_dentry_path = get_dentry_path_str(new_dentry);
save_str_to_buf(&p.event->args_buf, new_dentry_path, 1);

if (!evaluate_data_filters(&p, 0))
return 0;

return events_perf_submit(&p, 0);
}

Expand Down Expand Up @@ -4816,6 +4878,9 @@ statfunc int common_utimes(struct pt_regs *ctx)
save_to_submit_buf(&p.event->args_buf, &atime, sizeof(u64), 3);
save_to_submit_buf(&p.event->args_buf, &mtime, sizeof(u64), 4);

if (!evaluate_data_filters(&p, 0))
return 0;

return events_perf_submit(&p, 0);
}

Expand Down Expand Up @@ -4853,6 +4918,9 @@ int BPF_KPROBE(trace_do_truncate)
save_to_submit_buf(&p.event->args_buf, &dev, sizeof(dev_t), 2);
save_to_submit_buf(&p.event->args_buf, &length, sizeof(u64), 3);

if (!evaluate_data_filters(&p, 0))
return 0;

return events_perf_submit(&p, 0);
}

Expand Down Expand Up @@ -5043,6 +5111,9 @@ int BPF_KPROBE(trace_ret_inotify_find_inode)
save_to_submit_buf(&p.event->args_buf, &inode_nr, sizeof(unsigned long), 1);
save_to_submit_buf(&p.event->args_buf, &dev, sizeof(dev_t), 2);

if (!evaluate_data_filters(&p, 0))
return 0;

return events_perf_submit(&p, 0);
}

Expand Down Expand Up @@ -5197,6 +5268,9 @@ int BPF_KPROBE(trace_security_path_notify)
save_to_submit_buf(&p.event->args_buf, &mask, sizeof(u64), 3);
save_to_submit_buf(&p.event->args_buf, &obj_type, sizeof(unsigned int), 4);

if (!evaluate_data_filters(&p, 0))
return 0;

return events_perf_submit(&p, 0);
}

Expand Down Expand Up @@ -5300,6 +5374,9 @@ int BPF_KPROBE(trace_chmod_common)
save_str_to_buf(&p.event->args_buf, file_path, 0);
save_to_submit_buf(&p.event->args_buf, &mode, sizeof(umode_t), 1);

if (!evaluate_data_filters(&p, 0))
return 0;

return events_perf_submit(&p, 0);
}

Expand Down
70 changes: 59 additions & 11 deletions pkg/filters/data.go
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -44,6 +44,17 @@ func (kdf *KernelDataFilter) IsKernelFilterEnabled(field string) bool {
return false
}

// getKernelFieldName return only one field name with in-kernel filter
// TODO: need to retrieve all possible field names (and not only one)
func (kdf *KernelDataFilter) getKernelFieldName() string {
var key string
for k := range kdf.kernelFilters {
key = k
break
}
return key
}

type DataFilter struct {
filters map[string]Filter[*StringFilter]
kernelDataFilter *KernelDataFilter
Expand All @@ -61,6 +72,48 @@ func NewDataFilter() *DataFilter {
}
}

// list of events and field names allowed to have in-kernel filter
var allowedKernelField = map[events.ID]string{
// LSM hooks
events.SecurityBprmCheck: "pathname", // 0
events.SecurityFileOpen: "pathname", // 0
events.SecurityInodeUnlink: "pathname", // 0
events.SecuritySbMount: "path", // 1
events.SecurityBPFMap: "map_name", // 1
events.SecurityKernelReadFile: "pathname", // 0
events.SecurityInodeMknod: "file_name", // 0
events.SecurityPostReadFile: "pathname", // 0
events.SecurityInodeSymlinkEventId: "linkpath", // 0
events.SecurityMmapFile: "pathname", // 0
events.SecurityFileMprotect: "pathname", // 0
events.SecurityInodeRename: "old_path", // 0
events.SecurityBpfProg: "name", // 1
events.SecurityPathNotify: "pathname", // 0
events.SharedObjectLoaded: "pathname", // 0
// Syscalls
events.Execve: "pathname",
events.Execveat: "pathname",
// Others
events.ModuleLoad: "pathname",
events.InotifyWatch: "pathname",
events.DoTruncate: "pathname",
events.MagicWrite: "pathname",
events.VfsUtimes: "pathname",
events.LoadElfPhdrs: "pathname",
events.CallUsermodeHelper: "pathname",
events.ChmodCommon: "pathname",
events.DoMmap: "pathname",
}

// checkAvailabilityKernelFilter check if event ID and field name are allowed to be an kernel filter
func (f *DataFilter) checkAvailabilityKernelFilter(event events.ID, field string) bool {
if selectedField := allowedKernelField[event]; selectedField != field {
return false
}

return true
}

func (f *DataFilter) Equalities() (StringFilterEqualities, error) {
if !f.Enabled() {
return StringFilterEqualities{
Expand All @@ -73,8 +126,9 @@ func (f *DataFilter) Equalities() (StringFilterEqualities, error) {
}, nil
}

// selected data name
dataField := "pathname"
// get the field name for in-kernel filter
// TODO: only one allowed at the moment (more to come)
dataField := f.kernelDataFilter.getKernelFieldName()

fieldName, ok := f.filters[dataField]
if !ok {
Expand Down Expand Up @@ -166,12 +220,10 @@ func (f *DataFilter) Parse(id events.ID, fieldName string, operatorAndValues str
// valueHandler is passed to the filter constructor to allow for custom value handling
// before the filter is applied
valueHandler := func(val string) (string, error) {
switch id {
case events.SecurityFileOpen,
events.MagicWrite,
events.SecurityMmapFile:
if f.checkAvailabilityKernelFilter(id, fieldName) {
return f.processKernelFilter(val, fieldName)

}
switch id {
case events.SysEnter,
events.SysExit,
events.SuspiciousSyscallSource,
Expand Down Expand Up @@ -280,10 +332,6 @@ func (f *DataFilter) checkKernelFilterRestrictions(val string) error {
// enableKernelFilterArg activates a kernel filter for the specified data field.
// This function currently supports enabling filters for the "pathname" field only.
func (f *DataFilter) enableKernelFilterArg(fieldName string) {
if fieldName != "pathname" {
return
}

filter, ok := f.filters[fieldName]
if !ok {
return
Expand Down