215249f6ad
This patch adds selftests exercising the logic changed/added in the
previous patches in the series. A variety of successful and unsuccessful
rbtree usages are validated:
Success:
* Add some nodes, let map_value bpf_rbtree_root destructor clean them
up
* Add some nodes, remove one using the non-owning ref leftover by
successful rbtree_add() call
* Add some nodes, remove one using the non-owning ref returned by
rbtree_first() call
Failure:
* BTF where bpf_rb_root owns bpf_list_node should fail to load
* BTF where node of type X is added to tree containing nodes of type Y
should fail to load
* No calling rbtree api functions in 'less' callback for rbtree_add
* No releasing lock in 'less' callback for rbtree_add
* No removing a node which hasn't been added to any tree
* No adding a node which has already been added to a tree
* No escaping of non-owning references past their lock's
critical section
* No escaping of non-owning references past other invalidation points
(rbtree_remove)
These tests mostly focus on rbtree-specific additions, but some of the
failure cases revalidate scenarios common to both linked_list and rbtree
which are covered in the former's tests. Better to be a bit redundant in
case linked_list and rbtree semantics deviate over time.
Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
Link: https://lore.kernel.org/r/20230214004017.2534011-8-davemarchevsky@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
322 lines
7.4 KiB
C
322 lines
7.4 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#include <vmlinux.h>
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#include <bpf/bpf_tracing.h>
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#include <bpf/bpf_helpers.h>
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#include <bpf/bpf_core_read.h>
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#include "bpf_experimental.h"
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#include "bpf_misc.h"
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struct node_data {
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long key;
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long data;
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struct bpf_rb_node node;
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};
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#define private(name) SEC(".data." #name) __hidden __attribute__((aligned(8)))
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private(A) struct bpf_spin_lock glock;
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private(A) struct bpf_rb_root groot __contains(node_data, node);
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private(A) struct bpf_rb_root groot2 __contains(node_data, node);
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static bool less(struct bpf_rb_node *a, const struct bpf_rb_node *b)
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{
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struct node_data *node_a;
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struct node_data *node_b;
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node_a = container_of(a, struct node_data, node);
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node_b = container_of(b, struct node_data, node);
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return node_a->key < node_b->key;
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}
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SEC("?tc")
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__failure __msg("bpf_spin_lock at off=16 must be held for bpf_rb_root")
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long rbtree_api_nolock_add(void *ctx)
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{
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struct node_data *n;
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n = bpf_obj_new(typeof(*n));
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if (!n)
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return 1;
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bpf_rbtree_add(&groot, &n->node, less);
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return 0;
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}
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SEC("?tc")
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__failure __msg("bpf_spin_lock at off=16 must be held for bpf_rb_root")
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long rbtree_api_nolock_remove(void *ctx)
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{
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struct node_data *n;
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n = bpf_obj_new(typeof(*n));
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if (!n)
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return 1;
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bpf_spin_lock(&glock);
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bpf_rbtree_add(&groot, &n->node, less);
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bpf_spin_unlock(&glock);
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bpf_rbtree_remove(&groot, &n->node);
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return 0;
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}
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SEC("?tc")
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__failure __msg("bpf_spin_lock at off=16 must be held for bpf_rb_root")
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long rbtree_api_nolock_first(void *ctx)
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{
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bpf_rbtree_first(&groot);
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return 0;
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}
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SEC("?tc")
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__failure __msg("rbtree_remove node input must be non-owning ref")
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long rbtree_api_remove_unadded_node(void *ctx)
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{
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struct node_data *n, *m;
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struct bpf_rb_node *res;
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n = bpf_obj_new(typeof(*n));
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if (!n)
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return 1;
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m = bpf_obj_new(typeof(*m));
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if (!m) {
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bpf_obj_drop(n);
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return 1;
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}
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bpf_spin_lock(&glock);
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bpf_rbtree_add(&groot, &n->node, less);
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/* This remove should pass verifier */
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res = bpf_rbtree_remove(&groot, &n->node);
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n = container_of(res, struct node_data, node);
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/* This remove shouldn't, m isn't in an rbtree */
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res = bpf_rbtree_remove(&groot, &m->node);
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m = container_of(res, struct node_data, node);
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bpf_spin_unlock(&glock);
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if (n)
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bpf_obj_drop(n);
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if (m)
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bpf_obj_drop(m);
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return 0;
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}
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SEC("?tc")
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__failure __msg("Unreleased reference id=2 alloc_insn=11")
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long rbtree_api_remove_no_drop(void *ctx)
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{
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struct bpf_rb_node *res;
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struct node_data *n;
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bpf_spin_lock(&glock);
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res = bpf_rbtree_first(&groot);
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if (!res)
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goto unlock_err;
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res = bpf_rbtree_remove(&groot, res);
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n = container_of(res, struct node_data, node);
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bpf_spin_unlock(&glock);
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/* bpf_obj_drop(n) is missing here */
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return 0;
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unlock_err:
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bpf_spin_unlock(&glock);
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return 1;
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}
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SEC("?tc")
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__failure __msg("arg#1 expected pointer to allocated object")
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long rbtree_api_add_to_multiple_trees(void *ctx)
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{
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struct node_data *n;
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n = bpf_obj_new(typeof(*n));
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if (!n)
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return 1;
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bpf_spin_lock(&glock);
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bpf_rbtree_add(&groot, &n->node, less);
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/* This add should fail since n already in groot's tree */
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bpf_rbtree_add(&groot2, &n->node, less);
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bpf_spin_unlock(&glock);
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return 0;
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}
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SEC("?tc")
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__failure __msg("rbtree_remove node input must be non-owning ref")
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long rbtree_api_add_release_unlock_escape(void *ctx)
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{
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struct node_data *n;
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n = bpf_obj_new(typeof(*n));
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if (!n)
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return 1;
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bpf_spin_lock(&glock);
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bpf_rbtree_add(&groot, &n->node, less);
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bpf_spin_unlock(&glock);
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bpf_spin_lock(&glock);
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/* After add() in previous critical section, n should be
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* release_on_unlock and released after previous spin_unlock,
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* so should not be possible to use it here
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*/
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bpf_rbtree_remove(&groot, &n->node);
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bpf_spin_unlock(&glock);
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return 0;
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}
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SEC("?tc")
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__failure __msg("rbtree_remove node input must be non-owning ref")
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long rbtree_api_release_aliasing(void *ctx)
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{
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struct node_data *n, *m, *o;
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struct bpf_rb_node *res;
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n = bpf_obj_new(typeof(*n));
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if (!n)
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return 1;
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bpf_spin_lock(&glock);
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bpf_rbtree_add(&groot, &n->node, less);
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bpf_spin_unlock(&glock);
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bpf_spin_lock(&glock);
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/* m and o point to the same node,
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* but verifier doesn't know this
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*/
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res = bpf_rbtree_first(&groot);
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if (!res)
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return 1;
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o = container_of(res, struct node_data, node);
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res = bpf_rbtree_first(&groot);
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if (!res)
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return 1;
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m = container_of(res, struct node_data, node);
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bpf_rbtree_remove(&groot, &m->node);
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/* This second remove shouldn't be possible. Retval of previous
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* remove returns owning reference to m, which is the same
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* node o's non-owning ref is pointing at
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*
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* In order to preserve property
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* * owning ref must not be in rbtree
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* * non-owning ref must be in rbtree
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*
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* o's ref must be invalidated after previous remove. Otherwise
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* we'd have non-owning ref to node that isn't in rbtree, and
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* verifier wouldn't be able to use type system to prevent remove
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* of ref that already isn't in any tree. Would have to do runtime
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* checks in that case.
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*/
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bpf_rbtree_remove(&groot, &o->node);
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bpf_spin_unlock(&glock);
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return 0;
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}
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SEC("?tc")
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__failure __msg("rbtree_remove node input must be non-owning ref")
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long rbtree_api_first_release_unlock_escape(void *ctx)
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{
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struct bpf_rb_node *res;
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struct node_data *n;
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bpf_spin_lock(&glock);
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res = bpf_rbtree_first(&groot);
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if (res)
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n = container_of(res, struct node_data, node);
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bpf_spin_unlock(&glock);
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bpf_spin_lock(&glock);
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/* After first() in previous critical section, n should be
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* release_on_unlock and released after previous spin_unlock,
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* so should not be possible to use it here
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*/
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bpf_rbtree_remove(&groot, &n->node);
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bpf_spin_unlock(&glock);
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return 0;
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}
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static bool less__bad_fn_call_add(struct bpf_rb_node *a, const struct bpf_rb_node *b)
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{
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struct node_data *node_a;
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struct node_data *node_b;
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node_a = container_of(a, struct node_data, node);
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node_b = container_of(b, struct node_data, node);
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bpf_rbtree_add(&groot, &node_a->node, less);
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return node_a->key < node_b->key;
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}
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static bool less__bad_fn_call_remove(struct bpf_rb_node *a, const struct bpf_rb_node *b)
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{
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struct node_data *node_a;
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struct node_data *node_b;
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node_a = container_of(a, struct node_data, node);
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node_b = container_of(b, struct node_data, node);
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bpf_rbtree_remove(&groot, &node_a->node);
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return node_a->key < node_b->key;
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}
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static bool less__bad_fn_call_first_unlock_after(struct bpf_rb_node *a, const struct bpf_rb_node *b)
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{
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struct node_data *node_a;
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struct node_data *node_b;
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node_a = container_of(a, struct node_data, node);
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node_b = container_of(b, struct node_data, node);
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bpf_rbtree_first(&groot);
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bpf_spin_unlock(&glock);
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return node_a->key < node_b->key;
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}
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static __always_inline
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long add_with_cb(bool (cb)(struct bpf_rb_node *a, const struct bpf_rb_node *b))
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{
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struct node_data *n;
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n = bpf_obj_new(typeof(*n));
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if (!n)
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return 1;
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bpf_spin_lock(&glock);
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bpf_rbtree_add(&groot, &n->node, cb);
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bpf_spin_unlock(&glock);
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return 0;
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}
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SEC("?tc")
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__failure __msg("arg#1 expected pointer to allocated object")
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long rbtree_api_add_bad_cb_bad_fn_call_add(void *ctx)
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{
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return add_with_cb(less__bad_fn_call_add);
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}
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SEC("?tc")
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__failure __msg("rbtree_remove not allowed in rbtree cb")
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long rbtree_api_add_bad_cb_bad_fn_call_remove(void *ctx)
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{
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return add_with_cb(less__bad_fn_call_remove);
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}
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SEC("?tc")
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__failure __msg("can't spin_{lock,unlock} in rbtree cb")
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long rbtree_api_add_bad_cb_bad_fn_call_first_unlock_after(void *ctx)
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{
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return add_with_cb(less__bad_fn_call_first_unlock_after);
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}
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char _license[] SEC("license") = "GPL";
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