feat: add pgid filter

cmd/loadBpf.go

@@ -112,6 +112,7 @@ func LoadBpf(options *Options) {
 		ProxyPort:    options.ProxyPort,
 		ProxyPid:     pid,
 		FilterByPid:  len(options.Pids) > 0,
+		FilterByPgid: len(options.Pids) > 0,
 		FilterIp:     options.Ip4,
 		FilterIpMask: options.Ip4Mask,
 		EnableTcp:    options.EnableTCP,

cmd/proxy.c

@@ -24,6 +24,7 @@ struct Config {
   __u32  filter_ip;
   __u8 filter_ip_mask;
   bool filter_by_pid;
+  bool filter_by_pgid;
   bool enable_tcp;
   bool enable_udp;
   char command[TASK_COMM_LEN];
@@ -96,10 +97,26 @@ struct {
 #define SO_ORIGINAL_DST 80
 
 #define AF_INET 2
+
+static __always_inline __u32
+get_current_pgid(void)
+{
+  struct task_struct *task = (struct task_struct *)bpf_get_current_task_btf();
+  if (!task)
+    return 0;
+
+  /* PIDTYPE_PGID is 2 in kernel enum pid_type. */
+  struct pid *pgid_pid = BPF_CORE_READ(task, signal, pids[2]);
+  if (!pgid_pid)
+    return 0;
+
+  return BPF_CORE_READ(pgid_pid, numbers[0].nr);
+}
+
 static __always_inline bool
 match_process(struct Config *conf)
 {
-  if (conf->command[0] == '\0' && !conf->filter_by_pid){
+  if (conf->command[0] == '\0' && !conf->filter_by_pid && !conf->filter_by_pgid){
     return true;
   }
 
@@ -114,6 +131,11 @@ match_process(struct Config *conf)
     if (bpf_map_lookup_elem(&filter_pid_map, &current_pid)) return true;
   }
 
+  if(conf->filter_by_pgid){
+    __u32 current_pgid = get_current_pgid();
+    if (current_pgid && bpf_map_lookup_elem(&filter_pid_map, &current_pgid)) return true;
+  }
+
   return false;
 }