From: Kaitao Cheng <[email protected]> Extend refcounted_kptr test to exercise bpf_list_add: add a second node after the first, then bpf_list_del both nodes.
To verify the validity of bpf_list_add, also expect the verifier to reject calls to bpf_list_add made without holding the spin_lock. Signed-off-by: Kaitao Cheng <[email protected]> --- .../testing/selftests/bpf/bpf_experimental.h | 16 +++ .../selftests/bpf/progs/refcounted_kptr.c | 122 ++++++++++++++++-- 2 files changed, 124 insertions(+), 14 deletions(-) diff --git a/tools/testing/selftests/bpf/bpf_experimental.h b/tools/testing/selftests/bpf/bpf_experimental.h index 54ec9d307fdc..fdcc7a054095 100644 --- a/tools/testing/selftests/bpf/bpf_experimental.h +++ b/tools/testing/selftests/bpf/bpf_experimental.h @@ -110,6 +110,22 @@ extern struct bpf_list_node *bpf_list_pop_back(struct bpf_list_head *head) __ksy extern struct bpf_list_node *bpf_list_del(struct bpf_list_head *head, struct bpf_list_node *node) __ksym; +/* Description + * Insert 'new' after 'prev' in the BPF linked list with head 'head'. + * The bpf_spin_lock protecting the list must be held. 'prev' must already + * be in that list; 'new' must not be in any list. The 'meta' and 'off' + * parameters are rewritten by the verifier, no need for BPF programs to + * set them. + * Returns + * 0 on success, -EINVAL if head is NULL, prev is not in the list with head, + * or new is already in a list. + */ +extern int bpf_list_add_impl(struct bpf_list_head *head, struct bpf_list_node *new, + struct bpf_list_node *prev, void *meta, __u64 off) __ksym; + +/* Convenience macro to wrap over bpf_list_add_impl */ +#define bpf_list_add(head, new, prev) bpf_list_add_impl(head, new, prev, NULL, 0) + /* Description * Remove 'node' from rbtree with root 'root' * Returns diff --git a/tools/testing/selftests/bpf/progs/refcounted_kptr.c b/tools/testing/selftests/bpf/progs/refcounted_kptr.c index ac7672cfefb8..5a83274e1d26 100644 --- a/tools/testing/selftests/bpf/progs/refcounted_kptr.c +++ b/tools/testing/selftests/bpf/progs/refcounted_kptr.c @@ -367,18 +367,19 @@ long insert_rbtree_and_stash__del_tree_##rem_tree(void *ctx) \ INSERT_STASH_READ(true, "insert_stash_read: remove from tree"); INSERT_STASH_READ(false, "insert_stash_read: don't remove from tree"); -/* Insert node_data into both rbtree and list, remove from tree, then remove - * from list via bpf_list_del using the node obtained from the tree. +/* Insert one node in tree and list, remove it from tree, add a second + * node after it in list with bpf_list_add, then remove both nodes from + * list via bpf_list_del. */ SEC("tc") -__description("test_bpf_list_del: remove an arbitrary node from the list") +__description("test_list_add_del: test bpf_list_add/del") __success __retval(0) -long test_bpf_list_del(void *ctx) +long test_list_add_del(void *ctx) { - long err; + long err = 0; struct bpf_rb_node *rb; - struct bpf_list_node *l; - struct node_data *n; + struct bpf_list_node *l, *l_1; + struct node_data *n, *n_1, *m_1; err = __insert_in_tree_and_list(&head, &root, &lock); if (err) @@ -392,20 +393,48 @@ long test_bpf_list_del(void *ctx) } rb = bpf_rbtree_remove(&root, rb); - if (!rb) { - bpf_spin_unlock(&lock); + bpf_spin_unlock(&lock); + if (!rb) return -5; - } n = container_of(rb, struct node_data, r); + n_1 = bpf_obj_new(typeof(*n_1)); + if (!n_1) { + bpf_obj_drop(n); + return -1; + } + m_1 = bpf_refcount_acquire(n_1); + if (!m_1) { + bpf_obj_drop(n); + bpf_obj_drop(n_1); + return -1; + } + + bpf_spin_lock(&lock); + if (bpf_list_add(&head, &n_1->l, &n->l)) { + bpf_spin_unlock(&lock); + bpf_obj_drop(n); + bpf_obj_drop(m_1); + return -8; + } + l = bpf_list_del(&head, &n->l); + l_1 = bpf_list_del(&head, &m_1->l); bpf_spin_unlock(&lock); bpf_obj_drop(n); - if (!l) - return -6; + bpf_obj_drop(m_1); - bpf_obj_drop(container_of(l, struct node_data, l)); - return 0; + if (l) + bpf_obj_drop(container_of(l, struct node_data, l)); + else + err = -6; + + if (l_1) + bpf_obj_drop(container_of(l_1, struct node_data, l)); + else + err = -6; + + return err; } SEC("?tc") @@ -438,6 +467,71 @@ long list_del_without_lock_fail(void *ctx) return 0; } +SEC("?tc") +__failure __msg("bpf_spin_lock at off=32 must be held for bpf_list_head") +long list_add_without_lock_fail(void *ctx) +{ + long err = 0; + struct bpf_rb_node *rb; + struct bpf_list_node *l, *l_1; + struct node_data *n, *n_1, *m_1; + + err = __insert_in_tree_and_list(&head, &root, &lock); + if (err) + return err; + + bpf_spin_lock(&lock); + rb = bpf_rbtree_first(&root); + if (!rb) { + bpf_spin_unlock(&lock); + return -4; + } + + rb = bpf_rbtree_remove(&root, rb); + bpf_spin_unlock(&lock); + if (!rb) + return -5; + + n = container_of(rb, struct node_data, r); + n_1 = bpf_obj_new(typeof(*n_1)); + if (!n_1) { + bpf_obj_drop(n); + return -1; + } + m_1 = bpf_refcount_acquire(n_1); + if (!m_1) { + bpf_obj_drop(n); + bpf_obj_drop(n_1); + return -1; + } + + /* Intentionally no lock: verifier should reject bpf_list_add without lock */ + if (bpf_list_add(&head, &n_1->l, &n->l)) { + bpf_obj_drop(n); + bpf_obj_drop(m_1); + return -8; + } + + bpf_spin_lock(&lock); + l = bpf_list_del(&head, &n->l); + l_1 = bpf_list_del(&head, &m_1->l); + bpf_spin_unlock(&lock); + bpf_obj_drop(n); + bpf_obj_drop(m_1); + + if (l) + bpf_obj_drop(container_of(l, struct node_data, l)); + else + err = -6; + + if (l_1) + bpf_obj_drop(container_of(l_1, struct node_data, l)); + else + err = -6; + + return err; +} + SEC("tc") __success long rbtree_refcounted_node_ref_escapes(void *ctx) -- 2.50.1 (Apple Git-155)
