From: Kaitao Cheng <[email protected]> Add a new kfunc bpf_list_add(head, new, prev, meta, off) that inserts 'new' after 'prev' in the BPF linked list. Both must be in the same list; 'prev' must already be in the list. The new node must be an owning reference (e.g. from bpf_obj_new); the kfunc consumes that reference and the node becomes non-owning once inserted.
We have added an additional parameter bpf_list_head *head to bpf_list_add, as the verifier requires the head parameter to check whether the lock is being held. Returns 0 on success, -EINVAL if 'prev' is not in a list or 'new' is already in a list (or duplicate insertion). On failure, the kernel drops the passed-in node. Signed-off-by: Kaitao Cheng <[email protected]> Reviewed-by: Eduard Zingerman <[email protected]> --- kernel/bpf/helpers.c | 11 +++++++++++ kernel/bpf/verifier.c | 12 +++++++++--- 2 files changed, 20 insertions(+), 3 deletions(-) diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index 1c69476c8a09..89579165ef4d 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -2577,6 +2577,16 @@ __bpf_kfunc int bpf_list_push_back_impl(struct bpf_list_head *head, return bpf_list_push_back(head, node, meta__ign, off); } +__bpf_kfunc int bpf_list_add(struct bpf_list_head *head, struct bpf_list_node *new, + struct bpf_list_node *prev__nonown_allowed, + struct btf_struct_meta *meta, u64 off) +{ + struct bpf_list_node_kern *n = (void *)new, *p = (void *)prev__nonown_allowed; + struct list_head *prev_ptr = &p->list_head; + + return __bpf_list_add(n, head, &prev_ptr, meta ? meta->record : NULL, off); +} + static struct bpf_list_node *__bpf_list_del(struct bpf_list_head *head, struct list_head *n) { @@ -4756,6 +4766,7 @@ BTF_ID_FLAGS(func, bpf_list_push_front, KF_IMPLICIT_ARGS) BTF_ID_FLAGS(func, bpf_list_push_front_impl) BTF_ID_FLAGS(func, bpf_list_push_back, KF_IMPLICIT_ARGS) BTF_ID_FLAGS(func, bpf_list_push_back_impl) +BTF_ID_FLAGS(func, bpf_list_add, KF_IMPLICIT_ARGS) BTF_ID_FLAGS(func, bpf_list_pop_front, KF_ACQUIRE | KF_RET_NULL) BTF_ID_FLAGS(func, bpf_list_pop_back, KF_ACQUIRE | KF_RET_NULL) BTF_ID_FLAGS(func, bpf_list_del, KF_ACQUIRE | KF_RET_NULL) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 35eebb5e7769..662ad7312697 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -10959,6 +10959,7 @@ enum special_kfunc_type { KF_bpf_list_push_front, KF_bpf_list_push_back_impl, KF_bpf_list_push_back, + KF_bpf_list_add, KF_bpf_list_pop_front, KF_bpf_list_pop_back, KF_bpf_list_del, @@ -11028,6 +11029,7 @@ BTF_ID(func, bpf_list_push_front_impl) BTF_ID(func, bpf_list_push_front) BTF_ID(func, bpf_list_push_back_impl) BTF_ID(func, bpf_list_push_back) +BTF_ID(func, bpf_list_add) BTF_ID(func, bpf_list_pop_front) BTF_ID(func, bpf_list_pop_back) BTF_ID(func, bpf_list_del) @@ -11140,7 +11142,8 @@ static bool is_bpf_list_push_kfunc(u32 func_id) return func_id == special_kfunc_list[KF_bpf_list_push_front] || func_id == special_kfunc_list[KF_bpf_list_push_front_impl] || func_id == special_kfunc_list[KF_bpf_list_push_back] || - func_id == special_kfunc_list[KF_bpf_list_push_back_impl]; + func_id == special_kfunc_list[KF_bpf_list_push_back_impl] || + func_id == special_kfunc_list[KF_bpf_list_add]; } static bool is_bpf_rbtree_add_kfunc(u32 func_id) @@ -19524,8 +19527,11 @@ int bpf_fixup_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn, int struct_meta_reg = BPF_REG_3; int node_offset_reg = BPF_REG_4; - /* rbtree_add has extra 'less' arg, so args-to-fixup are in diff regs */ - if (is_bpf_rbtree_add_kfunc(desc->func_id)) { + /* list_add/rbtree_add have an extra arg (prev/less), + * so args-to-fixup are in diff regs. + */ + if (desc->func_id == special_kfunc_list[KF_bpf_list_add] || + is_bpf_rbtree_add_kfunc(desc->func_id)) { struct_meta_reg = BPF_REG_4; node_offset_reg = BPF_REG_5; } -- 2.50.1 (Apple Git-155)
