Commit 6147f151 authored by Dave Marchevsky's avatar Dave Marchevsky Committed by Alexei Starovoitov
Browse files

selftests/bpf: Add refcounted_kptr tests 



Test refcounted local kptr functionality added in previous patches in
the series.

Usecases which pass verification:

* Add refcounted local kptr to both tree and list. Then, read and -
  possibly, depending on test variant - delete from tree, then list.
  * Also test doing read-and-maybe-delete in opposite order
* Stash a refcounted local kptr in a map_value, then add it to a
  rbtree. Read from both, possibly deleting after tree read.
* Add refcounted local kptr to both tree and list. Then, try reading and
  deleting twice from one of the collections.
* bpf_refcount_acquire of just-added non-owning ref should work, as
  should bpf_refcount_acquire of owning ref just out of bpf_obj_new

Usecases which fail verification:

* The simple successful bpf_refcount_acquire cases from above should
  both fail to verify if the newly-acquired owning ref is not dropped

Signed-off-by: default avatarDave Marchevsky <davemarchevsky@fb.com>
Link: https://lore.kernel.org/r/20230415201811.343116-10-davemarchevsky@fb.com


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 3e81740a

tools/testing/selftests/bpf/prog_tests/refcounted_kptr.c

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// SPDX-License-Identifier: GPL-2.0

/* Copyright (c) 2023 Meta Platforms, Inc. and affiliates. */



#include <test_progs.h>

#include <network_helpers.h>



#include "refcounted_kptr.skel.h"

#include "refcounted_kptr_fail.skel.h"



void test_refcounted_kptr(void)

{

	RUN_TESTS(refcounted_kptr);

}



void test_refcounted_kptr_fail(void)

{

	RUN_TESTS(refcounted_kptr_fail);

}

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

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// SPDX-License-Identifier: GPL-2.0

/* Copyright (c) 2023 Meta Platforms, Inc. and affiliates. */



#include <vmlinux.h>

#include <bpf/bpf_tracing.h>

#include <bpf/bpf_helpers.h>

#include <bpf/bpf_core_read.h>

#include "bpf_misc.h"

#include "bpf_experimental.h"



struct node_data {

	long key;

	long list_data;

	struct bpf_rb_node r;

	struct bpf_list_node l;

	struct bpf_refcount ref;

};



struct map_value {

	struct node_data __kptr *node;

};



struct {

	__uint(type, BPF_MAP_TYPE_ARRAY);

	__type(key, int);

	__type(value, struct map_value);

	__uint(max_entries, 1);

} stashed_nodes SEC(".maps");



struct node_acquire {

	long key;

	long data;

	struct bpf_rb_node node;

	struct bpf_refcount refcount;

};



#define private(name) SEC(".bss." #name) __hidden __attribute__((aligned(8)))

private(A) struct bpf_spin_lock lock;

private(A) struct bpf_rb_root root __contains(node_data, r);

private(A) struct bpf_list_head head __contains(node_data, l);



private(B) struct bpf_spin_lock alock;

private(B) struct bpf_rb_root aroot __contains(node_acquire, node);



static bool less(struct bpf_rb_node *node_a, const struct bpf_rb_node *node_b)

{

	struct node_data *a;

	struct node_data *b;



	a = container_of(node_a, struct node_data, r);

	b = container_of(node_b, struct node_data, r);



	return a->key < b->key;

}



static bool less_a(struct bpf_rb_node *a, const struct bpf_rb_node *b)

{

	struct node_acquire *node_a;

	struct node_acquire *node_b;



	node_a = container_of(a, struct node_acquire, node);

	node_b = container_of(b, struct node_acquire, node);



	return node_a->key < node_b->key;

}



static long __insert_in_tree_and_list(struct bpf_list_head *head,

				      struct bpf_rb_root *root,

				      struct bpf_spin_lock *lock)

{

	struct node_data *n, *m;



	n = bpf_obj_new(typeof(*n));

	if (!n)

		return -1;



	m = bpf_refcount_acquire(n);

	m->key = 123;

	m->list_data = 456;



	bpf_spin_lock(lock);

	if (bpf_rbtree_add(root, &n->r, less)) {

		/* Failure to insert - unexpected */

		bpf_spin_unlock(lock);

		bpf_obj_drop(m);

		return -2;

	}

	bpf_spin_unlock(lock);



	bpf_spin_lock(lock);

	if (bpf_list_push_front(head, &m->l)) {

		/* Failure to insert - unexpected */

		bpf_spin_unlock(lock);

		return -3;

	}

	bpf_spin_unlock(lock);

	return 0;

}



static long __stash_map_insert_tree(int idx, int val, struct bpf_rb_root *root,

				    struct bpf_spin_lock *lock)

{

	struct map_value *mapval;

	struct node_data *n, *m;



	mapval = bpf_map_lookup_elem(&stashed_nodes, &idx);

	if (!mapval)

		return -1;



	n = bpf_obj_new(typeof(*n));

	if (!n)

		return -2;



	n->key = val;

	m = bpf_refcount_acquire(n);



	n = bpf_kptr_xchg(&mapval->node, n);

	if (n) {

		bpf_obj_drop(n);

		bpf_obj_drop(m);

		return -3;

	}



	bpf_spin_lock(lock);

	if (bpf_rbtree_add(root, &m->r, less)) {

		/* Failure to insert - unexpected */

		bpf_spin_unlock(lock);

		return -4;

	}

	bpf_spin_unlock(lock);

	return 0;

}



static long __read_from_tree(struct bpf_rb_root *root,

			     struct bpf_spin_lock *lock,

			     bool remove_from_tree)

{

	struct bpf_rb_node *rb;

	struct node_data *n;

	long res = -99;



	bpf_spin_lock(lock);



	rb = bpf_rbtree_first(root);

	if (!rb) {

		bpf_spin_unlock(lock);

		return -1;

	}



	n = container_of(rb, struct node_data, r);

	res = n->key;



	if (!remove_from_tree) {

		bpf_spin_unlock(lock);

		return res;

	}



	rb = bpf_rbtree_remove(root, rb);

	bpf_spin_unlock(lock);

	if (!rb)

		return -2;

	n = container_of(rb, struct node_data, r);

	bpf_obj_drop(n);

	return res;

}



static long __read_from_list(struct bpf_list_head *head,

			     struct bpf_spin_lock *lock,

			     bool remove_from_list)

{

	struct bpf_list_node *l;

	struct node_data *n;

	long res = -99;



	bpf_spin_lock(lock);



	l = bpf_list_pop_front(head);

	if (!l) {

		bpf_spin_unlock(lock);

		return -1;

	}



	n = container_of(l, struct node_data, l);

	res = n->list_data;



	if (!remove_from_list) {

		if (bpf_list_push_back(head, &n->l)) {

			bpf_spin_unlock(lock);

			return -2;

		}

	}



	bpf_spin_unlock(lock);



	if (remove_from_list)

		bpf_obj_drop(n);

	return res;

}



static long __read_from_unstash(int idx)

{

	struct node_data *n = NULL;

	struct map_value *mapval;

	long val = -99;



	mapval = bpf_map_lookup_elem(&stashed_nodes, &idx);

	if (!mapval)

		return -1;



	n = bpf_kptr_xchg(&mapval->node, n);

	if (!n)

		return -2;



	val = n->key;

	bpf_obj_drop(n);

	return val;

}



#define INSERT_READ_BOTH(rem_tree, rem_list, desc)			\

SEC("tc")								\

__description(desc)							\

__success __retval(579)							\

long insert_and_remove_tree_##rem_tree##_list_##rem_list(void *ctx)	\

{									\

	long err, tree_data, list_data;					\

									\

	err = __insert_in_tree_and_list(&head, &root, &lock);		\

	if (err)							\

		return err;						\

									\

	err = __read_from_tree(&root, &lock, rem_tree);			\

	if (err < 0)							\

		return err;						\

	else								\

		tree_data = err;					\

									\

	err = __read_from_list(&head, &lock, rem_list);			\

	if (err < 0)							\

		return err;						\

	else								\

		list_data = err;					\

									\

	return tree_data + list_data;					\

}



/* After successful insert of struct node_data into both collections:

 *   - it should have refcount = 2

 *   - removing / not removing the node_data from a collection after

 *     reading should have no effect on ability to read / remove from

 *     the other collection

 */

INSERT_READ_BOTH(true, true, "insert_read_both: remove from tree + list");

INSERT_READ_BOTH(false, false, "insert_read_both: remove from neither");

INSERT_READ_BOTH(true, false, "insert_read_both: remove from tree");

INSERT_READ_BOTH(false, true, "insert_read_both: remove from list");



#undef INSERT_READ_BOTH

#define INSERT_READ_BOTH(rem_tree, rem_list, desc)			\

SEC("tc")								\

__description(desc)							\

__success __retval(579)							\

long insert_and_remove_lf_tree_##rem_tree##_list_##rem_list(void *ctx)	\

{									\

	long err, tree_data, list_data;					\

									\

	err = __insert_in_tree_and_list(&head, &root, &lock);		\

	if (err)							\

		return err;						\

									\

	err = __read_from_list(&head, &lock, rem_list);			\

	if (err < 0)							\

		return err;						\

	else								\

		list_data = err;					\

									\

	err = __read_from_tree(&root, &lock, rem_tree);			\

	if (err < 0)							\

		return err;						\

	else								\

		tree_data = err;					\

									\

	return tree_data + list_data;					\

}



/* Similar to insert_read_both, but list data is read and possibly removed

 * first

 *

 * Results should be no different than reading and possibly removing rbtree

 * node first

 */

INSERT_READ_BOTH(true, true, "insert_read_both_list_first: remove from tree + list");

INSERT_READ_BOTH(false, false, "insert_read_both_list_first: remove from neither");

INSERT_READ_BOTH(true, false, "insert_read_both_list_first: remove from tree");

INSERT_READ_BOTH(false, true, "insert_read_both_list_first: remove from list");



#define INSERT_DOUBLE_READ_AND_DEL(read_fn, read_root, desc)		\

SEC("tc")								\

__description(desc)							\

__success __retval(-1)							\

long insert_double_##read_fn##_and_del_##read_root(void *ctx)		\

{									\

	long err, list_data;						\

									\

	err = __insert_in_tree_and_list(&head, &root, &lock);		\

	if (err)							\

		return err;						\

									\

	err = read_fn(&read_root, &lock, true);				\

	if (err < 0)							\

		return err;						\

	else								\

		list_data = err;					\

									\

	err = read_fn(&read_root, &lock, true);				\

	if (err < 0)							\

		return err;						\

									\

	return err + list_data;						\

}



/* Insert into both tree and list, then try reading-and-removing from either twice

 *

 * The second read-and-remove should fail on read step since the node has

 * already been removed

 */

INSERT_DOUBLE_READ_AND_DEL(__read_from_tree, root, "insert_double_del: 2x read-and-del from tree");

INSERT_DOUBLE_READ_AND_DEL(__read_from_list, head, "insert_double_del: 2x read-and-del from list");



#define INSERT_STASH_READ(rem_tree, desc)				\

SEC("tc")								\

__description(desc)							\

__success __retval(84)							\

long insert_rbtree_and_stash__del_tree_##rem_tree(void *ctx)		\

{									\

	long err, tree_data, map_data;					\

									\

	err = __stash_map_insert_tree(0, 42, &root, &lock);		\

	if (err)							\

		return err;						\

									\

	err = __read_from_tree(&root, &lock, rem_tree);			\

	if (err < 0)							\

		return err;						\

	else								\

		tree_data = err;					\

									\

	err = __read_from_unstash(0);					\

	if (err < 0)							\

		return err;						\

	else								\

		map_data = err;						\

									\

	return tree_data + map_data;					\

}



/* Stash a refcounted node in map_val, insert same node into tree, then try

 * reading data from tree then unstashed map_val, possibly removing from tree

 *

 * Removing from tree should have no effect on map_val kptr validity

 */

INSERT_STASH_READ(true, "insert_stash_read: remove from tree");

INSERT_STASH_READ(false, "insert_stash_read: don't remove from tree");



SEC("tc")

__success

long rbtree_refcounted_node_ref_escapes(void *ctx)

{

	struct node_acquire *n, *m;



	n = bpf_obj_new(typeof(*n));

	if (!n)

		return 1;



	bpf_spin_lock(&alock);

	bpf_rbtree_add(&aroot, &n->node, less_a);

	m = bpf_refcount_acquire(n);

	bpf_spin_unlock(&alock);



	m->key = 2;

	bpf_obj_drop(m);

	return 0;

}



SEC("tc")

__success

long rbtree_refcounted_node_ref_escapes_owning_input(void *ctx)

{

	struct node_acquire *n, *m;



	n = bpf_obj_new(typeof(*n));

	if (!n)

		return 1;



	m = bpf_refcount_acquire(n);

	m->key = 2;



	bpf_spin_lock(&alock);

	bpf_rbtree_add(&aroot, &n->node, less_a);

	bpf_spin_unlock(&alock);



	bpf_obj_drop(m);



	return 0;

}



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

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

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// 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_acquire {

	long key;

	long data;

	struct bpf_rb_node node;

	struct bpf_refcount refcount;

};



#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_acquire, node);



static bool less(struct bpf_rb_node *a, const struct bpf_rb_node *b)

{

	struct node_acquire *node_a;

	struct node_acquire *node_b;



	node_a = container_of(a, struct node_acquire, node);

	node_b = container_of(b, struct node_acquire, node);



	return node_a->key < node_b->key;

}



SEC("?tc")

__failure __msg("Unreleased reference id=3 alloc_insn=21")

long rbtree_refcounted_node_ref_escapes(void *ctx)

{

	struct node_acquire *n, *m;



	n = bpf_obj_new(typeof(*n));

	if (!n)

		return 1;



	bpf_spin_lock(&glock);

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

	/* m becomes an owning ref but is never drop'd or added to a tree */

	m = bpf_refcount_acquire(n);

	bpf_spin_unlock(&glock);



	m->key = 2;

	return 0;

}



SEC("?tc")

__failure __msg("Unreleased reference id=3 alloc_insn=9")

long rbtree_refcounted_node_ref_escapes_owning_input(void *ctx)

{

	struct node_acquire *n, *m;



	n = bpf_obj_new(typeof(*n));

	if (!n)

		return 1;



	/* m becomes an owning ref but is never drop'd or added to a tree */

	m = bpf_refcount_acquire(n);

	m->key = 2;



	bpf_spin_lock(&glock);

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

	bpf_spin_unlock(&glock);



	return 0;

}



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