Re: [RFC PATCH bpf-next 3/3] selftests/bpf: Add selftests for cgroup1 local storage

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On 12/5/23 9:37 AM, Yafang Shao wrote:
Expanding the test coverage from cgroup2 to include cgroup1. The result
as follows,

Already existing test cases for cgroup2:
   #48/1    cgrp_local_storage/tp_btf:OK
   #48/2    cgrp_local_storage/attach_cgroup:OK
   #48/3    cgrp_local_storage/recursion:OK
   #48/4    cgrp_local_storage/negative:OK
   #48/5    cgrp_local_storage/cgroup_iter_sleepable:OK
   #48/6    cgrp_local_storage/yes_rcu_lock:OK
   #48/7    cgrp_local_storage/no_rcu_lock:OK

Expanded test cases for cgroup1:
   #48/8    cgrp_local_storage/cgrp1_tp_btf:OK
   #48/9    cgrp_local_storage/cgrp1_recursion:OK
   #48/10   cgrp_local_storage/cgrp1_negative:OK
   #48/11   cgrp_local_storage/cgrp1_iter_sleepable:OK
   #48/12   cgrp_local_storage/cgrp1_yes_rcu_lock:OK
   #48/13   cgrp_local_storage/cgrp1_no_rcu_lock:OK

Summary:
   #48      cgrp_local_storage:OK
   Summary: 1/13 PASSED, 0 SKIPPED, 0 FAILED

Signed-off-by: Yafang Shao <laoar.shao@xxxxxxxxx>

LGTM with a few nits below.

Acked-by: Yonghong Song <yonghong.song@xxxxxxxxx>

---
  .../bpf/prog_tests/cgrp_local_storage.c       | 92 ++++++++++++++++++-
  .../selftests/bpf/progs/cgrp_ls_recursion.c   | 84 +++++++++++++----
  .../selftests/bpf/progs/cgrp_ls_sleepable.c   | 67 ++++++++++++--
  .../selftests/bpf/progs/cgrp_ls_tp_btf.c      | 82 ++++++++++++-----
  4 files changed, 278 insertions(+), 47 deletions(-)

diff --git a/tools/testing/selftests/bpf/prog_tests/cgrp_local_storage.c b/tools/testing/selftests/bpf/prog_tests/cgrp_local_storage.c
index 63e776f4176e..9524cde4cbf6 100644
--- a/tools/testing/selftests/bpf/prog_tests/cgrp_local_storage.c
+++ b/tools/testing/selftests/bpf/prog_tests/cgrp_local_storage.c
@@ -19,6 +19,9 @@ struct socket_cookie {
  	__u64 cookie_value;
  };
+bool is_cgroup1;
+int target_hid;
+
  static void test_tp_btf(int cgroup_fd)
  {
  	struct cgrp_ls_tp_btf *skel;
@@ -29,6 +32,9 @@ static void test_tp_btf(int cgroup_fd)
  	if (!ASSERT_OK_PTR(skel, "skel_open_and_load"))
  		return;
+ skel->bss->is_cgroup1 = is_cgroup1;
+	skel->bss->target_hid = target_hid;

Let reverse the order like below to be consistent with other code patterns:
+	skel->bss->target_hid = target_hid;
+	skel->bss->is_cgroup1 = is_cgroup1;

+
  	/* populate a value in map_b */
  	err = bpf_map_update_elem(bpf_map__fd(skel->maps.map_b), &cgroup_fd, &val1, BPF_ANY);
  	if (!ASSERT_OK(err, "map_update_elem"))
@@ -130,6 +136,9 @@ static void test_recursion(int cgroup_fd)
  	if (!ASSERT_OK_PTR(skel, "skel_open_and_load"))
  		return;
+ skel->bss->target_hid = target_hid;
+	skel->bss->is_cgroup1 = is_cgroup1;
+
  	err = cgrp_ls_recursion__attach(skel);
  	if (!ASSERT_OK(err, "skel_attach"))
  		goto out;
[...]
diff --git a/tools/testing/selftests/bpf/progs/cgrp_ls_sleepable.c b/tools/testing/selftests/bpf/progs/cgrp_ls_sleepable.c
index 4c7844e1dbfa..985ff419249c 100644
--- a/tools/testing/selftests/bpf/progs/cgrp_ls_sleepable.c
+++ b/tools/testing/selftests/bpf/progs/cgrp_ls_sleepable.c
@@ -17,7 +17,11 @@ struct {
__u32 target_pid;
  __u64 cgroup_id;
+int target_hid;
+bool is_cgroup1;
+struct cgroup *bpf_task_get_cgroup1(struct task_struct *task, int hierarchy_id) __ksym;
+void bpf_cgroup_release(struct cgroup *cgrp) __ksym;
  void bpf_rcu_read_lock(void) __ksym;
  void bpf_rcu_read_unlock(void) __ksym;
@@ -37,23 +41,56 @@ int cgroup_iter(struct bpf_iter__cgroup *ctx)
  	return 0;
  }
+static void __no_rcu_lock(struct cgroup *cgrp)
+{
+	long *ptr;
+
+	/* Note that trace rcu is held in sleepable prog, so we can use
+	 * bpf_cgrp_storage_get() in sleepable prog.
+	 */
+	ptr = bpf_cgrp_storage_get(&map_a, cgrp, 0,
+				   BPF_LOCAL_STORAGE_GET_F_CREATE);
+	if (ptr)
+		cgroup_id = cgrp->kn->id;
+}
+
  SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
-int no_rcu_lock(void *ctx)
+int cgrp1_no_rcu_lock(void *ctx)
  {
  	struct task_struct *task;
  	struct cgroup *cgrp;
-	long *ptr;
+
+	if (!is_cgroup1)
+		return 0;

Do we need this check? Looks like the user space controls whether it will
be loaded or not depending on whether it is cgrp1.

+
+	task = bpf_get_current_task_btf();
+	if (task->pid != target_pid)
+		return 0;
+
+	/* bpf_task_get_cgroup1 can work in sleepable prog */
+	cgrp = bpf_task_get_cgroup1(task, target_hid);
+	if (!cgrp)
+		return 0;
+
+	__no_rcu_lock(cgrp);
+	bpf_cgroup_release(cgrp);
+	return 0;
+}
+
+SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
+int no_rcu_lock(void *ctx)
+{
+	struct task_struct *task;
+
+	if (is_cgroup1)
+		return 0;

Same here, check is not needed.

task = bpf_get_current_task_btf();
  	if (task->pid != target_pid)
  		return 0;
/* task->cgroups is untrusted in sleepable prog outside of RCU CS */
-	cgrp = task->cgroups->dfl_cgrp;
-	ptr = bpf_cgrp_storage_get(&map_a, cgrp, 0,
-				   BPF_LOCAL_STORAGE_GET_F_CREATE);
-	if (ptr)
-		cgroup_id = cgrp->kn->id;
+	__no_rcu_lock(task->cgroups->dfl_cgrp);
  	return 0;
  }
@@ -68,6 +105,22 @@ int yes_rcu_lock(void *ctx)
  	if (task->pid != target_pid)
  		return 0;
+ if (is_cgroup1) {
+		bpf_rcu_read_lock();
+		cgrp = bpf_task_get_cgroup1(task, target_hid);
+		if (!cgrp) {
+			bpf_rcu_read_unlock();
+			return 0;
+		}
+
+		ptr = bpf_cgrp_storage_get(&map_a, cgrp, 0, BPF_LOCAL_STORAGE_GET_F_CREATE);
+		if (ptr)
+			cgroup_id = cgrp->kn->id;
+		bpf_cgroup_release(cgrp);
+		bpf_rcu_read_unlock();
+		return 0;
+	}
+
  	bpf_rcu_read_lock();
  	cgrp = task->cgroups->dfl_cgrp;
  	/* cgrp is trusted under RCU CS */

[...]





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