tools/testing/selftests/bpf/progs/rbtree_fail.c

// SPDX-License-Identifier: GPL-2.0
#include <vmlinux.h>
#include <bpf/bpf_tracing.h>
#include <bpf/bpf_helpers.h>
#include <bpf/bpf_core_read.h>
#include "bpf_experimental.h"
#include "bpf_misc.h"

struct node_data {
	long key;
	long data;
	struct bpf_rb_node node;
};

#define private(name) SEC(".data." #name) __hidden __attribute__((aligned(8)))
private(A) struct bpf_spin_lock glock;
private(A) struct bpf_rb_root groot __contains(node_data, node);
private(A) struct bpf_rb_root groot2 __contains(node_data, node);

static bool less(struct bpf_rb_node *a, const struct bpf_rb_node *b)
{
	struct node_data *node_a;
	struct node_data *node_b;

	node_a = container_of(a, struct node_data, node);
	node_b = container_of(b, struct node_data, node);

	return node_a->key < node_b->key;
}

SEC("?tc")
__failure __msg("bpf_spin_lock at off=16 must be held for bpf_rb_root")
long rbtree_api_nolock_add(void *ctx)
{
	struct node_data *n;

	n = bpf_obj_new(typeof(*n));
	if (!n)
		return 1;

	bpf_rbtree_add(&groot, &n->node, less);
	return 0;
}

SEC("?tc")
__failure __msg("bpf_spin_lock at off=16 must be held for bpf_rb_root")
long rbtree_api_nolock_remove(void *ctx)
{
	struct node_data *n;

	n = bpf_obj_new(typeof(*n));
	if (!n)
		return 1;

	bpf_spin_lock(&glock);
	bpf_rbtree_add(&groot, &n->node, less);
	bpf_spin_unlock(&glock);

	bpf_rbtree_remove(&groot, &n->node);
	return 0;
}

SEC("?tc")
__failure __msg("bpf_spin_lock at off=16 must be held for bpf_rb_root")
long rbtree_api_nolock_first(void *ctx)
{
	bpf_rbtree_first(&groot);
	return 0;
}

SEC("?tc")
__failure __msg("rbtree_remove node input must be non-owning ref")
long rbtree_api_remove_unadded_node(void *ctx)
{
	struct node_data *n, *m;
	struct bpf_rb_node *res;

	n = bpf_obj_new(typeof(*n));
	if (!n)
		return 1;

	m = bpf_obj_new(typeof(*m));
	if (!m) {
		bpf_obj_drop(n);
		return 1;
	}

	bpf_spin_lock(&glock);
	bpf_rbtree_add(&groot, &n->node, less);

	/* This remove should pass verifier */
	res = bpf_rbtree_remove(&groot, &n->node);
	n = container_of(res, struct node_data, node);

	/* This remove shouldn't, m isn't in an rbtree */
	res = bpf_rbtree_remove(&groot, &m->node);
	m = container_of(res, struct node_data, node);
	bpf_spin_unlock(&glock);

	if (n)
		bpf_obj_drop(n);
	if (m)
		bpf_obj_drop(m);
	return 0;
}

SEC("?tc")
__failure __msg("Unreleased reference id=2 alloc_insn=11")
long rbtree_api_remove_no_drop(void *ctx)
{
	struct bpf_rb_node *res;
	struct node_data *n;

	bpf_spin_lock(&glock);
	res = bpf_rbtree_first(&groot);
	if (!res)
		goto unlock_err;

	res = bpf_rbtree_remove(&groot, res);

	n = container_of(res, struct node_data, node);
	bpf_spin_unlock(&glock);

	/* bpf_obj_drop(n) is missing here */
	return 0;

unlock_err:
	bpf_spin_unlock(&glock);
	return 1;
}

SEC("?tc")
__failure __msg("arg#1 expected pointer to allocated object")
long rbtree_api_add_to_multiple_trees(void *ctx)
{
	struct node_data *n;

	n = bpf_obj_new(typeof(*n));
	if (!n)
		return 1;

	bpf_spin_lock(&glock);
	bpf_rbtree_add(&groot, &n->node, less);

	/* This add should fail since n already in groot's tree */
	bpf_rbtree_add(&groot2, &n->node, less);
	bpf_spin_unlock(&glock);
	return 0;
}

SEC("?tc")
__failure __msg("rbtree_remove node input must be non-owning ref")
long rbtree_api_add_release_unlock_escape(void *ctx)
{
	struct node_data *n;

	n = bpf_obj_new(typeof(*n));
	if (!n)
		return 1;

	bpf_spin_lock(&glock);
	bpf_rbtree_add(&groot, &n->node, less);
	bpf_spin_unlock(&glock);

	bpf_spin_lock(&glock);
	/* After add() in previous critical section, n should be
	 * release_on_unlock and released after previous spin_unlock,
	 * so should not be possible to use it here
	 */
	bpf_rbtree_remove(&groot, &n->node);
	bpf_spin_unlock(&glock);
	return 0;
}

SEC("?tc")
__failure __msg("rbtree_remove node input must be non-owning ref")
long rbtree_api_release_aliasing(void *ctx)
{
	struct node_data *n, *m, *o;
	struct bpf_rb_node *res;

	n = bpf_obj_new(typeof(*n));
	if (!n)
		return 1;

	bpf_spin_lock(&glock);
	bpf_rbtree_add(&groot, &n->node, less);
	bpf_spin_unlock(&glock);

	bpf_spin_lock(&glock);

	/* m and o point to the same node,
	 * but verifier doesn't know this
	 */
	res = bpf_rbtree_first(&groot);
	if (!res)
		return 1;
	o = container_of(res, struct node_data, node);

	res = bpf_rbtree_first(&groot);
	if (!res)
		return 1;
	m = container_of(res, struct node_data, node);

	bpf_rbtree_remove(&groot, &m->node);
	/* This second remove shouldn't be possible. Retval of previous
	 * remove returns owning reference to m, which is the same
	 * node o's non-owning ref is pointing at
	 *
	 * In order to preserve property
	 *   * owning ref must not be in rbtree
	 *   * non-owning ref must be in rbtree
	 *
	 * o's ref must be invalidated after previous remove. Otherwise
	 * we'd have non-owning ref to node that isn't in rbtree, and
	 * verifier wouldn't be able to use type system to prevent remove
	 * of ref that already isn't in any tree. Would have to do runtime
	 * checks in that case.
	 */
	bpf_rbtree_remove(&groot, &o->node);

	bpf_spin_unlock(&glock);
	return 0;
}

SEC("?tc")
__failure __msg("rbtree_remove node input must be non-owning ref")
long rbtree_api_first_release_unlock_escape(void *ctx)
{
	struct bpf_rb_node *res;
	struct node_data *n;

	bpf_spin_lock(&glock);
	res = bpf_rbtree_first(&groot);
	if (res)
		n = container_of(res, struct node_data, node);
	bpf_spin_unlock(&glock);

	bpf_spin_lock(&glock);
	/* After first() in previous critical section, n should be
	 * release_on_unlock and released after previous spin_unlock,
	 * so should not be possible to use it here
	 */
	bpf_rbtree_remove(&groot, &n->node);
	bpf_spin_unlock(&glock);
	return 0;
}

static bool less__bad_fn_call_add(struct bpf_rb_node *a, const struct bpf_rb_node *b)
{
	struct node_data *node_a;
	struct node_data *node_b;

	node_a = container_of(a, struct node_data, node);
	node_b = container_of(b, struct node_data, node);
	bpf_rbtree_add(&groot, &node_a->node, less);

	return node_a->key < node_b->key;
}

static bool less__bad_fn_call_remove(struct bpf_rb_node *a, const struct bpf_rb_node *b)
{
	struct node_data *node_a;
	struct node_data *node_b;

	node_a = container_of(a, struct node_data, node);
	node_b = container_of(b, struct node_data, node);
	bpf_rbtree_remove(&groot, &node_a->node);

	return node_a->key < node_b->key;
}

static bool less__bad_fn_call_first_unlock_after(struct bpf_rb_node *a, const struct bpf_rb_node *b)
{
	struct node_data *node_a;
	struct node_data *node_b;

	node_a = container_of(a, struct node_data, node);
	node_b = container_of(b, struct node_data, node);
	bpf_rbtree_first(&groot);
	bpf_spin_unlock(&glock);

	return node_a->key < node_b->key;
}

static __always_inline
long add_with_cb(bool (cb)(struct bpf_rb_node *a, const struct bpf_rb_node *b))
{
	struct node_data *n;

	n = bpf_obj_new(typeof(*n));
	if (!n)
		return 1;

	bpf_spin_lock(&glock);
	bpf_rbtree_add(&groot, &n->node, cb);
	bpf_spin_unlock(&glock);
	return 0;
}

SEC("?tc")
__failure __msg("arg#1 expected pointer to allocated object")
long rbtree_api_add_bad_cb_bad_fn_call_add(void *ctx)
{
	return add_with_cb(less__bad_fn_call_add);
}

SEC("?tc")
__failure __msg("rbtree_remove not allowed in rbtree cb")
long rbtree_api_add_bad_cb_bad_fn_call_remove(void *ctx)
{
	return add_with_cb(less__bad_fn_call_remove);
}

SEC("?tc")
__failure __msg("can't spin_{lock,unlock} in rbtree cb")
long rbtree_api_add_bad_cb_bad_fn_call_first_unlock_after(void *ctx)
{
	return add_with_cb(less__bad_fn_call_first_unlock_after);
}

char _license[] SEC("license") = "GPL";