tracee-ebpf: add security_bpf{,_map} events (#617)

Add the following events to tracee-ebpf:

 - security_bpf: allows bpf() syscall command to be traced.
 - security_bpf_map: called from bpf() BPF_MAP_GET_FD_BY_ID command.

The first is important for generic bpf syscall tracing while the later
is triggered whenever some process tries to get an eBPF MAP fd in order
to read or update MAP contents: an important feature for tampering
prevention.

Signed-off-by: Rafael David Tinoco <rafaeldtinoco@gmail.com>

tracee-ebpf/tracee/consts.go

@@ -160,6 +160,8 @@ const (
 	SecuritySocketAcceptEventID
 	SecuritySocketBindEventID
 	SecuritySbMountEventID
+	SecurityBPFEventID
+	SecurityBPFMapEventID
 	MaxEventID
 )
 
@@ -538,6 +540,8 @@ var EventsIDToEvent = map[int32]EventConfig{
 	SecuritySocketAcceptEventID:  {ID: SecuritySocketAcceptEventID, ID32Bit: sys32undefined, Name: "security_socket_accept", Probes: []probe{{event: "security_socket_accept", attach: kprobe, fn: "trace_security_socket_accept"}}, Sets: []string{"lsm_hooks"}},
 	SecuritySocketBindEventID:    {ID: SecuritySocketBindEventID, ID32Bit: sys32undefined, Name: "security_socket_bind", Probes: []probe{{event: "security_socket_bind", attach: kprobe, fn: "trace_security_socket_bind"}}, Sets: []string{"lsm_hooks"}},
 	SecuritySbMountEventID:       {ID: SecuritySbMountEventID, ID32Bit: sys32undefined, Name: "security_sb_mount", Probes: []probe{{event: "security_sb_mount", attach: kprobe, fn: "trace_security_sb_mount"}}, Sets: []string{"default", "lsm_hooks"}},
+	SecurityBPFEventID:           {ID: SecurityBPFEventID, ID32Bit: sys32undefined, Name: "security_bpf", Probes: []probe{{event: "security_bpf", attach: kprobe, fn: "trace_security_bpf"}}, Sets: []string{"lsm_hooks"}},
+	SecurityBPFMapEventID:        {ID: SecurityBPFMapEventID, ID32Bit: sys32undefined, Name: "security_bpf_map", Probes: []probe{{event: "security_bpf_map", attach: kprobe, fn: "trace_security_bpf_map"}}, Sets: []string{"lsm_hooks"}},
 }
 
 // EventsIDToParams is list of the parameters (name and type) used by the events
@@ -903,4 +907,6 @@ var EventsIDToParams = map[int32][]external.ArgMeta{
 	SecuritySocketAcceptEventID:  {{Type: "int", Name: "sockfd"}, {Type: "struct sockaddr*", Name: "local_addr"}},
 	SecuritySocketBindEventID:    {{Type: "int", Name: "sockfd"}, {Type: "struct sockaddr*", Name: "local_addr"}},
 	SecuritySbMountEventID:       {{Type: "const char*", Name: "dev_name"}, {Type: "const char*", Name: "path"}, {Type: "const char*", Name: "type"}, {Type: "unsigned long", Name: "flags"}},
+	SecurityBPFEventID:           {{Type: "int", Name: "cmd"}},
+	SecurityBPFMapEventID:        {{Type: "unsigned int", Name: "map_id"}, {Type: "const char*", Name: "map_name"}},
 }

tracee-ebpf/tracee/tracee.bpf.c

@@ -163,7 +163,9 @@
 #define SECURITY_SOCKET_ACCEPT  1017
 #define SECURITY_SOCKET_BIND    1018
 #define SECURITY_SB_MOUNT       1019
-#define MAX_EVENT_ID            1020
+#define SECURITY_BPF            1020
+#define SECURITY_BPF_MAP        1021
+#define MAX_EVENT_ID            1022
 
 #define CONFIG_SHOW_SYSCALL         1
 #define CONFIG_EXEC_ENV             2
@@ -3105,6 +3107,68 @@ int BPF_KPROBE(trace_mprotect_alert)
     return 0;
 }
 
+#define BPF_OBJ_NAME_LEN 16U
+
+SEC("kprobe/security_bpf")
+int BPF_KPROBE(trace_security_bpf)
+{
+    if (!should_trace())
+        return 0;
+
+    buf_t *submit_p = get_buf(SUBMIT_BUF_IDX);
+    if (submit_p == NULL)
+        return 0;
+
+    set_buf_off(SUBMIT_BUF_IDX, sizeof(context_t));
+
+    context_t context = init_and_save_context(ctx, submit_p, SECURITY_BPF, 1 /*argnum*/, 0 /*ret*/);
+
+    u64 *tags = bpf_map_lookup_elem(&params_names_map, &context.eventid);
+    if (!tags)
+        return -1;
+
+    /* 1st argument == cmd (int) */
+    int cmd = (int)PT_REGS_PARM1(ctx);
+
+    save_to_submit_buf(submit_p, (void *)&cmd, sizeof(int), INT_T, DEC_ARG(0, *tags));
+
+    events_perf_submit(ctx);
+    return 0;
+};
+
+SEC("kprobe/security_bpf_map")
+int BPF_KPROBE(trace_security_bpf_map)
+{
+    if (!should_trace())
+        return 0;
+
+    buf_t *submit_p = get_buf(SUBMIT_BUF_IDX);
+    if (submit_p == NULL)
+        return 0;
+
+    set_buf_off(SUBMIT_BUF_IDX, sizeof(context_t));
+
+    context_t context = init_and_save_context(ctx, submit_p, SECURITY_BPF_MAP, 2 /*argnum*/, 0 /*ret*/);
+
+    u64 *tags = bpf_map_lookup_elem(&params_names_map, &context.eventid);
+    if (!tags)
+        return -1;
+
+    struct bpf_map *map;
+    char map_name[BPF_OBJ_NAME_LEN];
+
+    map = (struct bpf_map *)PT_REGS_PARM1(ctx);
+    bpf_probe_read_kernel_str(&map_name, BPF_OBJ_NAME_LEN, (void *)&map->name);
+
+    /* 1st argument == map_id (u32) */
+    save_to_submit_buf(submit_p, (void *)&map->id, sizeof(int), UINT_T, DEC_ARG(0, *tags));
+    /* 2nd argument == map_name (const char *) */
+    save_str_to_buf(submit_p, (void *)&map_name, DEC_ARG(1, *tags));
+
+    events_perf_submit(ctx);
+    return 0;
+}
+
 char LICENSE[] SEC("license") = "GPL";
 int KERNEL_VERSION SEC("version") = LINUX_VERSION_CODE;