From: Dave Marchevsky davemarchevsky@fb.com
[ Upstream commit bd1279ae8a691d7ec75852c6d0a22139afb034a4 ]
This patch adds implementations of bpf_rbtree_{add,remove,first} and teaches verifier about their BTF_IDs as well as those of bpf_rb_{root,node}.
All three kfuncs have some nonstandard component to their verification that needs to be addressed in future patches before programs can properly use them:
* bpf_rbtree_add: Takes 'less' callback, need to verify it
* bpf_rbtree_first: Returns ptr_to_node_type(off=rb_node_off) instead of ptr_to_rb_node(off=0). Return value ref is non-owning.
* bpf_rbtree_remove: Returns ptr_to_node_type(off=rb_node_off) instead of ptr_to_rb_node(off=0). 2nd arg (node) is a non-owning reference.
Signed-off-by: Dave Marchevsky davemarchevsky@fb.com Link: https://lore.kernel.org/r/20230214004017.2534011-3-davemarchevsky@fb.com Signed-off-by: Alexei Starovoitov ast@kernel.org Stable-dep-of: f6a6a5a97628 ("bpf: Fix struct_meta lookup for bpf_obj_free_fields kfunc call") Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/bpf/helpers.c | 54 +++++++++++++++++++++++++++++++++++++++++++ kernel/bpf/verifier.c | 14 ++++++++++- 2 files changed, 67 insertions(+), 1 deletion(-)
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index 92a57cc106656..5b692a5f2946b 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -1873,6 +1873,56 @@ struct bpf_list_node *bpf_list_pop_back(struct bpf_list_head *head) return __bpf_list_del(head, true); }
+__bpf_kfunc struct bpf_rb_node *bpf_rbtree_remove(struct bpf_rb_root *root, + struct bpf_rb_node *node) +{ + struct rb_root_cached *r = (struct rb_root_cached *)root; + struct rb_node *n = (struct rb_node *)node; + + rb_erase_cached(n, r); + RB_CLEAR_NODE(n); + return (struct bpf_rb_node *)n; +} + +/* Need to copy rbtree_add_cached's logic here because our 'less' is a BPF + * program + */ +static void __bpf_rbtree_add(struct bpf_rb_root *root, struct bpf_rb_node *node, + void *less) +{ + struct rb_node **link = &((struct rb_root_cached *)root)->rb_root.rb_node; + bpf_callback_t cb = (bpf_callback_t)less; + struct rb_node *parent = NULL; + bool leftmost = true; + + while (*link) { + parent = *link; + if (cb((uintptr_t)node, (uintptr_t)parent, 0, 0, 0)) { + link = &parent->rb_left; + } else { + link = &parent->rb_right; + leftmost = false; + } + } + + rb_link_node((struct rb_node *)node, parent, link); + rb_insert_color_cached((struct rb_node *)node, + (struct rb_root_cached *)root, leftmost); +} + +__bpf_kfunc void bpf_rbtree_add(struct bpf_rb_root *root, struct bpf_rb_node *node, + bool (less)(struct bpf_rb_node *a, const struct bpf_rb_node *b)) +{ + __bpf_rbtree_add(root, node, (void *)less); +} + +__bpf_kfunc struct bpf_rb_node *bpf_rbtree_first(struct bpf_rb_root *root) +{ + struct rb_root_cached *r = (struct rb_root_cached *)root; + + return (struct bpf_rb_node *)rb_first_cached(r); +} + /** * bpf_task_acquire - Acquire a reference to a task. A task acquired by this * kfunc which is not stored in a map as a kptr, must be released by calling @@ -2097,6 +2147,10 @@ BTF_ID_FLAGS(func, bpf_task_acquire, KF_ACQUIRE | KF_TRUSTED_ARGS) BTF_ID_FLAGS(func, bpf_task_acquire_not_zero, KF_ACQUIRE | KF_RCU | KF_RET_NULL) BTF_ID_FLAGS(func, bpf_task_kptr_get, KF_ACQUIRE | KF_KPTR_GET | KF_RET_NULL) BTF_ID_FLAGS(func, bpf_task_release, KF_RELEASE) +BTF_ID_FLAGS(func, bpf_rbtree_remove, KF_ACQUIRE) +BTF_ID_FLAGS(func, bpf_rbtree_add) +BTF_ID_FLAGS(func, bpf_rbtree_first, KF_RET_NULL) + #ifdef CONFIG_CGROUPS BTF_ID_FLAGS(func, bpf_cgroup_acquire, KF_ACQUIRE | KF_TRUSTED_ARGS) BTF_ID_FLAGS(func, bpf_cgroup_kptr_get, KF_ACQUIRE | KF_KPTR_GET | KF_RET_NULL) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 975f30e4f8612..2997869917613 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -8555,6 +8555,8 @@ BTF_ID_LIST(kf_arg_btf_ids) BTF_ID(struct, bpf_dynptr_kern) BTF_ID(struct, bpf_list_head) BTF_ID(struct, bpf_list_node) +BTF_ID(struct, bpf_rb_root) +BTF_ID(struct, bpf_rb_node)
static bool __is_kfunc_ptr_arg_type(const struct btf *btf, const struct btf_param *arg, int type) @@ -8660,6 +8662,9 @@ enum special_kfunc_type { KF_bpf_rdonly_cast, KF_bpf_rcu_read_lock, KF_bpf_rcu_read_unlock, + KF_bpf_rbtree_remove, + KF_bpf_rbtree_add, + KF_bpf_rbtree_first, };
BTF_SET_START(special_kfunc_set) @@ -8671,6 +8676,9 @@ BTF_ID(func, bpf_list_pop_front) BTF_ID(func, bpf_list_pop_back) BTF_ID(func, bpf_cast_to_kern_ctx) BTF_ID(func, bpf_rdonly_cast) +BTF_ID(func, bpf_rbtree_remove) +BTF_ID(func, bpf_rbtree_add) +BTF_ID(func, bpf_rbtree_first) BTF_SET_END(special_kfunc_set)
BTF_ID_LIST(special_kfunc_list) @@ -8684,6 +8692,9 @@ BTF_ID(func, bpf_cast_to_kern_ctx) BTF_ID(func, bpf_rdonly_cast) BTF_ID(func, bpf_rcu_read_lock) BTF_ID(func, bpf_rcu_read_unlock) +BTF_ID(func, bpf_rbtree_remove) +BTF_ID(func, bpf_rbtree_add) +BTF_ID(func, bpf_rbtree_first)
static bool is_kfunc_bpf_rcu_read_lock(struct bpf_kfunc_call_arg_meta *meta) { @@ -9439,7 +9450,8 @@ static int check_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn, }
if (meta.func_id == special_kfunc_list[KF_bpf_list_push_front] || - meta.func_id == special_kfunc_list[KF_bpf_list_push_back]) { + meta.func_id == special_kfunc_list[KF_bpf_list_push_back] || + meta.func_id == special_kfunc_list[KF_bpf_rbtree_add]) { release_ref_obj_id = regs[BPF_REG_2].ref_obj_id; err = ref_convert_owning_non_owning(env, release_ref_obj_id); if (err) {