feat: added capability hook

Signed-off-by: Aryan-sharma11 <aryan1126.sharma@gmail.com>

KubeArmor/BPF/enforcer.bpf.c

@@ -437,4 +437,134 @@ int BPF_PROG(enforce_file_perm, struct file *file, int mask) {
 
   struct path f_path = BPF_CORE_READ(file, f_path);
   return match_and_enforce_path_hooks(&f_path, dfilewrite, _FILE_PERMISSION);
+}
+SEC("lsm/capable")
+int BPF_PROG(enforce_cap,  const struct cred *cred, struct user_namespace *ns ,int cap, int ret){
+
+  event *task_info;
+
+  struct task_struct *t = (struct task_struct *)bpf_get_current_task();
+
+  bool match = false;
+
+  struct outer_key okey;
+  get_outer_key(&okey, t);
+
+  u32 *inner = bpf_map_lookup_elem(&kubearmor_containers, &okey);
+
+  if (!inner) {
+    return 0;
+  }
+
+  u32 zero = 0;
+  bufs_k *z = bpf_map_lookup_elem(&bufk, &zero);
+  if (z == NULL)
+    return 0;
+
+  u32 one = 1;
+  bufs_k *p = bpf_map_lookup_elem(&bufk, &one);
+  if (p == NULL)
+    return 0;
+
+  u32 two = 2;
+  bufs_k *store = bpf_map_lookup_elem(&bufk, &two);
+  if (store == NULL)
+    return 0;
+
+  bpf_map_update_elem(&bufk, &one, z, BPF_ANY);
+  int p0;
+  int p1;
+
+  struct data_t *val = bpf_map_lookup_elem(inner, p);
+  bool fromSourceCheck = true;
+
+ struct file *file_p = get_task_file(t);
+  if (file_p == NULL)
+    fromSourceCheck = false;
+  bufs_t *src_buf = get_buf(PATH_BUFFER);
+  if (src_buf == NULL)
+    fromSourceCheck = false;
+  struct path f_src = BPF_CORE_READ(file_p, f_path);
+  if (!prepend_path(&f_src, src_buf))
+    fromSourceCheck = false;
+
+  u32 *src_offset = get_buf_off(PATH_BUFFER);
+  if (src_offset == NULL)
+    fromSourceCheck = false;
+
+  void *ptr = &src_buf->buf[*src_offset];
+
+ if (fromSourceCheck) {
+    bpf_probe_read_str(p->source, MAX_STRING_SIZE, ptr);
+    p0 = CAPABLE_KEY;
+    p1 = cap;
+    p->path[0] = p0 ;
+    p->path[1] = p1 ;
+    val = bpf_map_lookup_elem(inner, p);
+
+    if (val) {
+      match = true;
+      goto decision;
+    }
+
+  val = bpf_map_lookup_elem(inner, p);
+    }
+
+  bpf_map_update_elem(&bufk, &one, z, BPF_ANY);
+
+  p->path[0] = p0;
+  p->path[1] = p1;
+
+  val = bpf_map_lookup_elem(inner, p);
+
+  if (val) {
+    match = true;
+    goto decision;
+  }
+ decision:
+
+  task_info = bpf_ringbuf_reserve(&kubearmor_events, sizeof(event), 0);
+  if (!task_info) {
+    return 0;
+  }
+  // Clearing arrays to avoid garbage values to be parsed
+  __builtin_memset(task_info->data.path, 0, sizeof(task_info->data.path));
+  __builtin_memset(task_info->data.source, 0, sizeof(task_info->data.source));
+
+  init_context(task_info);
+  bpf_probe_read_str(&task_info->data.path, MAX_STRING_SIZE, p->path);
+  bpf_probe_read_str(&task_info->data.source, MAX_STRING_SIZE, p->source);
+
+  task_info->event_id = _CAPABLE;
+
+  task_info->retval = -EPERM;
+
+  bpf_map_update_elem(&bufk, &one, z, BPF_ANY);
+  p->path[0] = dcap;
+  struct data_t *allow = bpf_map_lookup_elem(inner, p);
+
+  if (allow) {
+    if (!match) {
+      if(allow->processmask == BLOCK_POSTURE) {
+        bpf_ringbuf_submit(task_info, BPF_RB_FORCE_WAKEUP);
+        return -EPERM;
+      } else {
+          task_info->retval = 0;
+          bpf_ringbuf_submit(task_info, BPF_RB_FORCE_WAKEUP);
+          return 0;
+        }
+    }  
+  } else {
+        if (match) {
+          if (val && (val->processmask & RULE_DENY)) {
+              bpf_ringbuf_submit(task_info, BPF_RB_FORCE_WAKEUP);
+              return -EPERM;
+          }
+        }
+      }
+  bpf_ringbuf_discard(task_info, BPF_RB_NO_WAKEUP);
+
+
+return 0;
+
 }

KubeArmor/BPF/shared.h

@@ -21,13 +21,15 @@ char LICENSE[] SEC("license") = "Dual BSD/GPL";
 #define TASK_COMM_LEN 80
 #define AUDIT_POSTURE 140
 #define BLOCK_POSTURE 141
+#define CAPABLE_KEY 200
 
 enum file_hook_type { dpath = 0, dfileread, dfilewrite };
 
 enum deny_by_default {
   dproc = 101,
   dfile,
-  dnet
+  dnet,
+  dcap
 }; // check if the list is whitelist/blacklist
 enum network_check_type {
   sock_type = 2,

KubeArmor/BPF/syscalls.h

@@ -28,6 +28,9 @@ enum
     //process
     _SECURITY_BPRM_CHECK = 352,
 
+    // capabilities
+    _CAPABLE = 464,
+
 
 };
 #endif /* __SYSCALLS_H */

KubeArmor/enforcer/bpflsm/enforcer.go

@@ -139,6 +139,11 @@ func NewBPFEnforcer(node tp.Node, pinpath string, logger *fd.Feeder, monitor *mo
 		be.Logger.Errf("opening lsm %s: %s", be.obj.EnforceNetAccept.String(), err)
 		return be, err
 	}
+	be.Probes[be.obj.EnforceCap.String()], err = link.AttachLSM(link.LSMOptions{Program: be.obj.EnforceCap})
+	if err != nil {
+		be.Logger.Errf("opening lsm %s: %s", be.obj.EnforceCap.String(), err)
+		return be, err
+	}
 
 	/*
 		Path Hooks
@@ -338,6 +343,11 @@ func (be *BPFEnforcer) TraceEvents() {
 			log.Source = string(bytes.Trim(event.Data.Source[:], "\x00"))
 			log.Resource = string(bytes.Trim(event.Data.Path[:], "\x00"))
 			log.Data = "lsm=" + mon.GetSyscallName(int32(event.EventID))
+
+		case mon.Capable:
+			log.Operation = "Capabilities"
+			log.Resource = mon.Capabilities[int32(event.Data.Path[1])]
+			log.Data = "lsm=" + mon.GetSyscallName(int32(event.EventID)) + " " + log.Resource
 		}
 		if event.Retval >= 0 {
 			log.Result = "Passed"