linux-kernel - [PATCH bpf-next] bpf: allow bpf_current_task_under_cgroup() with BPF_CGROUP

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Message-ID: <20240722182050.38513-1-technoboy85@gmail.com>
Date: Mon, 22 Jul 2024 20:20:50 +0200
From: technoboy85@...il.com
To: Alexei Starovoitov <ast@...nel.org>,
	Daniel Borkmann <daniel@...earbox.net>,
	Steven Rostedt <rostedt@...dmis.org>,
	Masami Hiramatsu <mhiramat@...nel.org>,
	bpf@...r.kernel.org,
	linux-trace-kernel@...r.kernel.org
Cc: linux-kernel@...r.kernel.org,
	Matteo Croce <teknoraver@...a.com>
Subject: [PATCH bpf-next] bpf: allow bpf_current_task_under_cgroup() with BPF_CGROUP_*

From: Matteo Croce <teknoraver@...a.com>

The helper bpf_current_task_under_cgroup() currently is only allowed for
tracing programs.
Allow its usage also in the BPF_CGROUP_* program types.
Move the code from kernel/trace/bpf_trace.c to kernel/bpf/cgroup.c,
so it compiles also without CONFIG_BPF_EVENTS.

Signed-off-by: Matteo Croce <teknoraver@...a.com>
---
 include/linux/bpf.h      |  1 +
 kernel/bpf/cgroup.c      | 25 +++++++++++++++++++++++++
 kernel/trace/bpf_trace.c | 27 ++-------------------------
 3 files changed, 28 insertions(+), 25 deletions(-)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 4f1d4a97b9d1..4000fd161dda 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -3188,6 +3188,7 @@ extern const struct bpf_func_proto bpf_sock_hash_update_proto;
 extern const struct bpf_func_proto bpf_get_current_cgroup_id_proto;
 extern const struct bpf_func_proto bpf_get_current_ancestor_cgroup_id_proto;
 extern const struct bpf_func_proto bpf_get_cgroup_classid_curr_proto;
+extern const struct bpf_func_proto bpf_current_task_under_cgroup_proto;
 extern const struct bpf_func_proto bpf_msg_redirect_hash_proto;
 extern const struct bpf_func_proto bpf_msg_redirect_map_proto;
 extern const struct bpf_func_proto bpf_sk_redirect_hash_proto;
diff --git a/kernel/bpf/cgroup.c b/kernel/bpf/cgroup.c
index 8ba73042a239..b99add9570e6 100644
--- a/kernel/bpf/cgroup.c
+++ b/kernel/bpf/cgroup.c
@@ -2308,6 +2308,29 @@ static const struct bpf_func_proto bpf_get_netns_cookie_sockopt_proto = {
 };
 #endif
 
+BPF_CALL_2(bpf_current_task_under_cgroup, struct bpf_map *, map, u32, idx)
+{
+	struct bpf_array *array = container_of(map, struct bpf_array, map);
+	struct cgroup *cgrp;
+
+	if (unlikely(idx >= array->map.max_entries))
+		return -E2BIG;
+
+	cgrp = READ_ONCE(array->ptrs[idx]);
+	if (unlikely(!cgrp))
+		return -EAGAIN;
+
+	return task_under_cgroup_hierarchy(current, cgrp);
+}
+
+const struct bpf_func_proto bpf_current_task_under_cgroup_proto = {
+	.func           = bpf_current_task_under_cgroup,
+	.gpl_only       = false,
+	.ret_type       = RET_INTEGER,
+	.arg1_type      = ARG_CONST_MAP_PTR,
+	.arg2_type      = ARG_ANYTHING,
+};
+
 static const struct bpf_func_proto *
 cg_sockopt_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 {
@@ -2581,6 +2604,8 @@ cgroup_current_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 	case BPF_FUNC_get_cgroup_classid:
 		return &bpf_get_cgroup_classid_curr_proto;
 #endif
+	case BPF_FUNC_current_task_under_cgroup:
+		return &bpf_current_task_under_cgroup_proto;
 	default:
 		return NULL;
 	}
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index cd098846e251..ea5cdd122024 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -798,29 +798,6 @@ const struct bpf_func_proto bpf_task_pt_regs_proto = {
 	.ret_btf_id	= &bpf_task_pt_regs_ids[0],
 };
 
-BPF_CALL_2(bpf_current_task_under_cgroup, struct bpf_map *, map, u32, idx)
-{
-	struct bpf_array *array = container_of(map, struct bpf_array, map);
-	struct cgroup *cgrp;
-
-	if (unlikely(idx >= array->map.max_entries))
-		return -E2BIG;
-
-	cgrp = READ_ONCE(array->ptrs[idx]);
-	if (unlikely(!cgrp))
-		return -EAGAIN;
-
-	return task_under_cgroup_hierarchy(current, cgrp);
-}
-
-static const struct bpf_func_proto bpf_current_task_under_cgroup_proto = {
-	.func           = bpf_current_task_under_cgroup,
-	.gpl_only       = false,
-	.ret_type       = RET_INTEGER,
-	.arg1_type      = ARG_CONST_MAP_PTR,
-	.arg2_type      = ARG_ANYTHING,
-};
-
 struct send_signal_irq_work {
 	struct irq_work irq_work;
 	struct task_struct *task;
@@ -1548,8 +1525,6 @@ bpf_tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 		return &bpf_get_numa_node_id_proto;
 	case BPF_FUNC_perf_event_read:
 		return &bpf_perf_event_read_proto;
-	case BPF_FUNC_current_task_under_cgroup:
-		return &bpf_current_task_under_cgroup_proto;
 	case BPF_FUNC_get_prandom_u32:
 		return &bpf_get_prandom_u32_proto;
 	case BPF_FUNC_probe_write_user:
@@ -1578,6 +1553,8 @@ bpf_tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 		return &bpf_cgrp_storage_get_proto;
 	case BPF_FUNC_cgrp_storage_delete:
 		return &bpf_cgrp_storage_delete_proto;
+	case BPF_FUNC_current_task_under_cgroup:
+		return &bpf_current_task_under_cgroup_proto;
 #endif
 	case BPF_FUNC_send_signal:
 		return &bpf_send_signal_proto;
-- 
2.45.2