1 files changed, 330 insertions, 0 deletions

diff --git a/tools/testing/selftests/bpf/progs/rcu_read_lock.c b/tools/testing/selftests/bpf/progs/rcu_read_lock.c
new file mode 100644
index 000000000..5cecbdbbb
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/rcu_read_lock.c
@@ -0,0 +1,330 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */
+
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+#include "bpf_tracing_net.h"
+#include "bpf_misc.h"
+
+char _license[] SEC("license") = "GPL";
+
+struct {
+	__uint(type, BPF_MAP_TYPE_TASK_STORAGE);
+	__uint(map_flags, BPF_F_NO_PREALLOC);
+	__type(key, int);
+	__type(value, long);
+} map_a SEC(".maps");
+
+__u32 user_data, key_serial, target_pid;
+__u64 flags, task_storage_val, cgroup_id;
+
+struct bpf_key *bpf_lookup_user_key(__u32 serial, __u64 flags) __ksym;
+void bpf_key_put(struct bpf_key *key) __ksym;
+void bpf_rcu_read_lock(void) __ksym;
+void bpf_rcu_read_unlock(void) __ksym;
+struct task_struct *bpf_task_acquire_not_zero(struct task_struct *p) __ksym;
+void bpf_task_release(struct task_struct *p) __ksym;
+
+SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
+int get_cgroup_id(void *ctx)
+{
+	struct task_struct *task;
+	struct css_set *cgroups;
+
+	task = bpf_get_current_task_btf();
+	if (task->pid != target_pid)
+		return 0;
+
+	/* simulate bpf_get_current_cgroup_id() helper */
+	bpf_rcu_read_lock();
+	cgroups = task->cgroups;
+	if (!cgroups)
+		goto unlock;
+	cgroup_id = cgroups->dfl_cgrp->kn->id;
+unlock:
+	bpf_rcu_read_unlock();
+	return 0;
+}
+
+SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
+int task_succ(void *ctx)
+{
+	struct task_struct *task, *real_parent;
+	long init_val = 2;
+	long *ptr;
+
+	task = bpf_get_current_task_btf();
+	if (task->pid != target_pid)
+		return 0;
+
+	bpf_rcu_read_lock();
+	/* region including helper using rcu ptr real_parent */
+	real_parent = task->real_parent;
+	if (!real_parent)
+		goto out;
+	ptr = bpf_task_storage_get(&map_a, real_parent, &init_val,
+				   BPF_LOCAL_STORAGE_GET_F_CREATE);
+	if (!ptr)
+		goto out;
+	ptr = bpf_task_storage_get(&map_a, real_parent, 0, 0);
+	if (!ptr)
+		goto out;
+	task_storage_val = *ptr;
+out:
+	bpf_rcu_read_unlock();
+	return 0;
+}
+
+SEC("?fentry.s/" SYS_PREFIX "sys_nanosleep")
+int no_lock(void *ctx)
+{
+	struct task_struct *task, *real_parent;
+
+	/* no bpf_rcu_read_lock(), old code still works */
+	task = bpf_get_current_task_btf();
+	real_parent = task->real_parent;
+	(void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
+	return 0;
+}
+
+SEC("?fentry.s/" SYS_PREFIX "sys_nanosleep")
+int two_regions(void *ctx)
+{
+	struct task_struct *task, *real_parent;
+
+	/* two regions */
+	task = bpf_get_current_task_btf();
+	bpf_rcu_read_lock();
+	bpf_rcu_read_unlock();
+	bpf_rcu_read_lock();
+	real_parent = task->real_parent;
+	if (!real_parent)
+		goto out;
+	(void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
+out:
+	bpf_rcu_read_unlock();
+	return 0;
+}
+
+SEC("?fentry/" SYS_PREFIX "sys_getpgid")
+int non_sleepable_1(void *ctx)
+{
+	struct task_struct *task, *real_parent;
+
+	task = bpf_get_current_task_btf();
+	bpf_rcu_read_lock();
+	real_parent = task->real_parent;
+	if (!real_parent)
+		goto out;
+	(void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
+out:
+	bpf_rcu_read_unlock();
+	return 0;
+}
+
+SEC("?fentry/" SYS_PREFIX "sys_getpgid")
+int non_sleepable_2(void *ctx)
+{
+	struct task_struct *task, *real_parent;
+
+	bpf_rcu_read_lock();
+	task = bpf_get_current_task_btf();
+	bpf_rcu_read_unlock();
+
+	bpf_rcu_read_lock();
+	real_parent = task->real_parent;
+	if (!real_parent)
+		goto out;
+	(void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
+out:
+	bpf_rcu_read_unlock();
+	return 0;
+}
+
+SEC("?fentry.s/" SYS_PREFIX "sys_nanosleep")
+int task_acquire(void *ctx)
+{
+	struct task_struct *task, *real_parent, *gparent;
+
+	task = bpf_get_current_task_btf();
+	bpf_rcu_read_lock();
+	real_parent = task->real_parent;
+	if (!real_parent)
+		goto out;
+
+	/* rcu_ptr->rcu_field */
+	gparent = real_parent->real_parent;
+	if (!gparent)
+		goto out;
+
+	/* acquire a reference which can be used outside rcu read lock region */
+	gparent = bpf_task_acquire_not_zero(gparent);
+	if (!gparent)
+		/* Until we resolve the issues with using task->rcu_users, we
+		 * expect bpf_task_acquire_not_zero() to return a NULL task.
+		 * See the comment at the definition of
+		 * bpf_task_acquire_not_zero() for more details.
+		 */
+		goto out;
+
+	(void)bpf_task_storage_get(&map_a, gparent, 0, 0);
+	bpf_task_release(gparent);
+out:
+	bpf_rcu_read_unlock();
+	return 0;
+}
+
+SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
+int miss_lock(void *ctx)
+{
+	struct task_struct *task;
+	struct css_set *cgroups;
+	struct cgroup *dfl_cgrp;
+
+	/* missing bpf_rcu_read_lock() */
+	task = bpf_get_current_task_btf();
+	bpf_rcu_read_lock();
+	(void)bpf_task_storage_get(&map_a, task, 0, 0);
+	bpf_rcu_read_unlock();
+	bpf_rcu_read_unlock();
+	return 0;
+}
+
+SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
+int miss_unlock(void *ctx)
+{
+	struct task_struct *task;
+	struct css_set *cgroups;
+	struct cgroup *dfl_cgrp;
+
+	/* missing bpf_rcu_read_unlock() */
+	task = bpf_get_current_task_btf();
+	bpf_rcu_read_lock();
+	(void)bpf_task_storage_get(&map_a, task, 0, 0);
+	return 0;
+}
+
+SEC("?fentry/" SYS_PREFIX "sys_getpgid")
+int non_sleepable_rcu_mismatch(void *ctx)
+{
+	struct task_struct *task, *real_parent;
+
+	task = bpf_get_current_task_btf();
+	/* non-sleepable: missing bpf_rcu_read_unlock() in one path */
+	bpf_rcu_read_lock();
+	real_parent = task->real_parent;
+	if (!real_parent)
+		goto out;
+	(void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
+	if (real_parent)
+		bpf_rcu_read_unlock();
+out:
+	return 0;
+}
+
+SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
+int inproper_sleepable_helper(void *ctx)
+{
+	struct task_struct *task, *real_parent;
+	struct pt_regs *regs;
+	__u32 value = 0;
+	void *ptr;
+
+	task = bpf_get_current_task_btf();
+	/* sleepable helper in rcu read lock region */
+	bpf_rcu_read_lock();
+	real_parent = task->real_parent;
+	if (!real_parent)
+		goto out;
+	regs = (struct pt_regs *)bpf_task_pt_regs(real_parent);
+	if (!regs)
+		goto out;
+
+	ptr = (void *)PT_REGS_IP(regs);
+	(void)bpf_copy_from_user_task(&value, sizeof(uint32_t), ptr, task, 0);
+	user_data = value;
+	(void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
+out:
+	bpf_rcu_read_unlock();
+	return 0;
+}
+
+SEC("?lsm.s/bpf")
+int BPF_PROG(inproper_sleepable_kfunc, int cmd, union bpf_attr *attr, unsigned int size)
+{
+	struct bpf_key *bkey;
+
+	/* sleepable kfunc in rcu read lock region */
+	bpf_rcu_read_lock();
+	bkey = bpf_lookup_user_key(key_serial, flags);
+	bpf_rcu_read_unlock();
+	if (!bkey)
+		return -1;
+	bpf_key_put(bkey);
+
+	return 0;
+}
+
+SEC("?fentry.s/" SYS_PREFIX "sys_nanosleep")
+int nested_rcu_region(void *ctx)
+{
+	struct task_struct *task, *real_parent;
+
+	/* nested rcu read lock regions */
+	task = bpf_get_current_task_btf();
+	bpf_rcu_read_lock();
+	bpf_rcu_read_lock();
+	real_parent = task->real_parent;
+	if (!real_parent)
+		goto out;
+	(void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
+out:
+	bpf_rcu_read_unlock();
+	bpf_rcu_read_unlock();
+	return 0;
+}
+
+SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
+int task_untrusted_non_rcuptr(void *ctx)
+{
+	struct task_struct *task, *group_leader;
+
+	task = bpf_get_current_task_btf();
+	bpf_rcu_read_lock();
+	/* the pointer group_leader marked as untrusted */
+	group_leader = task->real_parent->group_leader;
+	(void)bpf_task_storage_get(&map_a, group_leader, 0, 0);
+	bpf_rcu_read_unlock();
+	return 0;
+}
+
+SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
+int task_untrusted_rcuptr(void *ctx)
+{
+	struct task_struct *task, *real_parent;
+
+	task = bpf_get_current_task_btf();
+	bpf_rcu_read_lock();
+	real_parent = task->real_parent;
+	bpf_rcu_read_unlock();
+	/* helper use of rcu ptr outside the rcu read lock region */
+	(void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
+	return 0;
+}
+
+SEC("?fentry.s/" SYS_PREFIX "sys_nanosleep")
+int cross_rcu_region(void *ctx)
+{
+	struct task_struct *task, *real_parent;
+
+	/* rcu ptr define/use in different regions */
+	task = bpf_get_current_task_btf();
+	bpf_rcu_read_lock();
+	real_parent = task->real_parent;
+	bpf_rcu_read_unlock();
+	bpf_rcu_read_lock();
+	(void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
+	bpf_rcu_read_unlock();
+	return 0;
+}