scx_layered: Add user and group layers

scheds/rust/scx_layered/src/bpf/intf.h

@@ -107,6 +107,8 @@ enum layer_match_kind {
 	MATCH_NICE_ABOVE,
 	MATCH_NICE_BELOW,
 	MATCH_NICE_EQUALS,
+	MATCH_USER_ID_EQUALS,
+	MATCH_GROUP_ID_EQUALS,
 
 	NR_LAYER_MATCH_KINDS,
 };
@@ -117,6 +119,8 @@ struct layer_match {
 	char		comm_prefix[MAX_COMM];
 	char		pcomm_prefix[MAX_COMM];
 	int		nice;
+	u32		user_id;
+	u32		group_id;
 };
 
 struct layer_match_ands {

scheds/rust/scx_layered/src/bpf/main.bpf.c

@@ -900,6 +900,9 @@ void BPF_STRUCT_OPS(layered_dispatch, s32 cpu, struct task_struct *prev)
 
 static bool match_one(struct layer_match *match, struct task_struct *p, const char *cgrp_path)
 {
+	bool result = false;
+	struct cred *cred;
+
 	switch (match->kind) {
 	case MATCH_CGROUP_PREFIX: {
 		return match_prefix(match->cgroup_prefix, cgrp_path, MAX_PATH);
@@ -921,9 +924,23 @@ static bool match_one(struct layer_match *match, struct task_struct *p, const ch
 		return prio_to_nice((s32)p->static_prio) < match->nice;
 	case MATCH_NICE_EQUALS:
 		return prio_to_nice((s32)p->static_prio) == match->nice;
+	case MATCH_USER_ID_EQUALS:
+		bpf_rcu_read_lock();
+		cred = p->real_cred;
+		if (cred)
+			result = cred->euid.val == match->user_id;
+		bpf_rcu_read_unlock();
+		return result;
+	case MATCH_GROUP_ID_EQUALS:
+		bpf_rcu_read_lock();
+		cred = p->real_cred;
+		if (cred)
+			result = cred->egid.val == match->group_id;
+		bpf_rcu_read_unlock();
+		return result;
 	default:
 		scx_bpf_error("invalid match kind %d", match->kind);
-		return false;
+		return result;
 	}
 }
 
@@ -1495,6 +1512,12 @@ s32 BPF_STRUCT_OPS_SLEEPABLE(layered_init)
 				case MATCH_NICE_EQUALS:
 					dbg("%s NICE_EQUALS %d", header, match->nice);
 					break;
+				case MATCH_USER_ID_EQUALS:
+					dbg("%s USER_ID %u", header, match->user_id);
+					break;
+				case MATCH_GROUP_ID_EQUALS:
+					dbg("%s GROUP_ID %u", header, match->group_id);
+					break;
 				default:
 					scx_bpf_error("%s Invalid kind", header);
 					return -EINVAL;

scheds/rust/scx_layered/src/main.rs

@@ -125,6 +125,10 @@ lazy_static::lazy_static! {
 /// - NiceEquals: Matches if the task's nice value is exactly equal to
 ///   the pattern.
 ///
+/// - UIDEquals: Matches if the task's effective user id matches the pattern.
+///
+/// - GIDEquals: Matches if the task's effective group id matches the pattern.
+///
 /// While there are complexity limitations as the matches are performed in
 /// BPF, it is straightforward to add more types of matches.
 ///
@@ -340,6 +344,8 @@ enum LayerMatch {
     NiceAbove(i32),
     NiceBelow(i32),
     NiceEquals(i32),
+    UIDEquals(u32),
+    GIDEquals(u32),
 }
 
 #[derive(Clone, Debug, Serialize, Deserialize)]
@@ -1289,6 +1295,14 @@ impl<'a, 'b> Scheduler<'a, 'b> {
                             mt.kind = bpf_intf::layer_match_kind_MATCH_NICE_EQUALS as i32;
                             mt.nice = *nice;
                         }
+                        LayerMatch::UIDEquals(user_id) => {
+                            mt.kind = bpf_intf::layer_match_kind_MATCH_USER_ID_EQUALS as i32;
+                            mt.user_id = *user_id;
+                        }
+                        LayerMatch::GIDEquals(group_id) => {
+                            mt.kind = bpf_intf::layer_match_kind_MATCH_GROUP_ID_EQUALS as i32;
+                            mt.group_id = *group_id;
+                        }
                     }
                 }
                 layer.matches[or_i].nr_match_ands = or.len() as i32;