From patchwork Mon May 9 22:42:52 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Joanne Koong X-Patchwork-Id: 12844152 X-Patchwork-Delegate: bpf@iogearbox.net Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 69869C433F5 for ; Mon, 9 May 2022 22:44:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229696AbiEIWsc (ORCPT ); Mon, 9 May 2022 18:48:32 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40830 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230431AbiEIWsb (ORCPT ); Mon, 9 May 2022 18:48:31 -0400 Received: from 66-220-155-178.mail-mxout.facebook.com (66-220-155-178.mail-mxout.facebook.com [66.220.155.178]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3AF252A28C8 for ; Mon, 9 May 2022 15:44:32 -0700 (PDT) Received: by devbig010.atn6.facebook.com (Postfix, from userid 115148) id 5B637C2576CA; Mon, 9 May 2022 15:44:18 -0700 (PDT) From: Joanne Koong To: bpf@vger.kernel.org Cc: andrii@kernel.org, ast@kernel.org, daniel@iogearbox.net, Joanne Koong Subject: [PATCH bpf-next v4 1/6] bpf: Add MEM_UNINIT as a bpf_type_flag Date: Mon, 9 May 2022 15:42:52 -0700 Message-Id: <20220509224257.3222614-2-joannelkoong@gmail.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20220509224257.3222614-1-joannelkoong@gmail.com> References: <20220509224257.3222614-1-joannelkoong@gmail.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net Instead of having uninitialized versions of arguments as separate bpf_arg_types (eg ARG_PTR_TO_UNINIT_MEM as the uninitialized version of ARG_PTR_TO_MEM), we can instead use MEM_UNINIT as a bpf_type_flag modifier to denote that the argument is uninitialized. Doing so cleans up some of the logic in the verifier. We no longer need to do two checks against an argument type (eg "if (base_type(arg_type) == ARG_PTR_TO_MEM || base_type(arg_type) == ARG_PTR_TO_UNINIT_MEM)"), since uninitialized and initialized versions of the same argument type will now share the same base type. In the near future, MEM_UNINIT will be used by dynptr helper functions as well. Signed-off-by: Joanne Koong Acked-by: Andrii Nakryiko Acked-by: David Vernet --- include/linux/bpf.h | 17 +++++++++-------- kernel/bpf/helpers.c | 4 ++-- kernel/bpf/verifier.c | 28 ++++++++-------------------- 3 files changed, 19 insertions(+), 30 deletions(-) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index be94833d390a..d0c167865504 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -389,7 +389,9 @@ enum bpf_type_flag { */ PTR_UNTRUSTED = BIT(6 + BPF_BASE_TYPE_BITS), - __BPF_TYPE_LAST_FLAG = PTR_UNTRUSTED, + MEM_UNINIT = BIT(7 + BPF_BASE_TYPE_BITS), + + __BPF_TYPE_LAST_FLAG = MEM_UNINIT, }; /* Max number of base types. */ @@ -408,16 +410,11 @@ enum bpf_arg_type { ARG_CONST_MAP_PTR, /* const argument used as pointer to bpf_map */ ARG_PTR_TO_MAP_KEY, /* pointer to stack used as map key */ ARG_PTR_TO_MAP_VALUE, /* pointer to stack used as map value */ - ARG_PTR_TO_UNINIT_MAP_VALUE, /* pointer to valid memory used to store a map value */ - /* the following constraints used to prototype bpf_memcmp() and other - * functions that access data on eBPF program stack + /* Used to prototype bpf_memcmp() and other functions that access data + * on eBPF program stack */ ARG_PTR_TO_MEM, /* pointer to valid memory (stack, packet, map value) */ - ARG_PTR_TO_UNINIT_MEM, /* pointer to memory does not need to be initialized, - * helper function must fill all bytes or clear - * them in error case. - */ ARG_CONST_SIZE, /* number of bytes accessed from memory */ ARG_CONST_SIZE_OR_ZERO, /* number of bytes accessed from memory or 0 */ @@ -449,6 +446,10 @@ enum bpf_arg_type { ARG_PTR_TO_ALLOC_MEM_OR_NULL = PTR_MAYBE_NULL | ARG_PTR_TO_ALLOC_MEM, ARG_PTR_TO_STACK_OR_NULL = PTR_MAYBE_NULL | ARG_PTR_TO_STACK, ARG_PTR_TO_BTF_ID_OR_NULL = PTR_MAYBE_NULL | ARG_PTR_TO_BTF_ID, + /* pointer to memory does not need to be initialized, helper function must fill + * all bytes or clear them in error case. + */ + ARG_PTR_TO_UNINIT_MEM = MEM_UNINIT | ARG_PTR_TO_MEM, /* This must be the last entry. Its purpose is to ensure the enum is * wide enough to hold the higher bits reserved for bpf_type_flag. diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index 3e709fed5306..8a2398ac14c2 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -103,7 +103,7 @@ const struct bpf_func_proto bpf_map_pop_elem_proto = { .gpl_only = false, .ret_type = RET_INTEGER, .arg1_type = ARG_CONST_MAP_PTR, - .arg2_type = ARG_PTR_TO_UNINIT_MAP_VALUE, + .arg2_type = ARG_PTR_TO_MAP_VALUE | MEM_UNINIT, }; BPF_CALL_2(bpf_map_peek_elem, struct bpf_map *, map, void *, value) @@ -116,7 +116,7 @@ const struct bpf_func_proto bpf_map_peek_elem_proto = { .gpl_only = false, .ret_type = RET_INTEGER, .arg1_type = ARG_CONST_MAP_PTR, - .arg2_type = ARG_PTR_TO_UNINIT_MAP_VALUE, + .arg2_type = ARG_PTR_TO_MAP_VALUE | MEM_UNINIT, }; const struct bpf_func_proto bpf_get_prandom_u32_proto = { diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 813f6ee80419..0fe1dea520ae 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -5378,12 +5378,6 @@ static int process_kptr_func(struct bpf_verifier_env *env, int regno, return 0; } -static bool arg_type_is_mem_ptr(enum bpf_arg_type type) -{ - return base_type(type) == ARG_PTR_TO_MEM || - base_type(type) == ARG_PTR_TO_UNINIT_MEM; -} - static bool arg_type_is_mem_size(enum bpf_arg_type type) { return type == ARG_CONST_SIZE || @@ -5523,7 +5517,6 @@ static const struct bpf_reg_types kptr_types = { .types = { PTR_TO_MAP_VALUE } } static const struct bpf_reg_types *compatible_reg_types[__BPF_ARG_TYPE_MAX] = { [ARG_PTR_TO_MAP_KEY] = &map_key_value_types, [ARG_PTR_TO_MAP_VALUE] = &map_key_value_types, - [ARG_PTR_TO_UNINIT_MAP_VALUE] = &map_key_value_types, [ARG_CONST_SIZE] = &scalar_types, [ARG_CONST_SIZE_OR_ZERO] = &scalar_types, [ARG_CONST_ALLOC_SIZE_OR_ZERO] = &scalar_types, @@ -5537,7 +5530,6 @@ static const struct bpf_reg_types *compatible_reg_types[__BPF_ARG_TYPE_MAX] = { [ARG_PTR_TO_BTF_ID] = &btf_ptr_types, [ARG_PTR_TO_SPIN_LOCK] = &spin_lock_types, [ARG_PTR_TO_MEM] = &mem_types, - [ARG_PTR_TO_UNINIT_MEM] = &mem_types, [ARG_PTR_TO_ALLOC_MEM] = &alloc_mem_types, [ARG_PTR_TO_INT] = &int_ptr_types, [ARG_PTR_TO_LONG] = &int_ptr_types, @@ -5711,8 +5703,7 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 arg, return -EACCES; } - if (base_type(arg_type) == ARG_PTR_TO_MAP_VALUE || - base_type(arg_type) == ARG_PTR_TO_UNINIT_MAP_VALUE) { + if (base_type(arg_type) == ARG_PTR_TO_MAP_VALUE) { err = resolve_map_arg_type(env, meta, &arg_type); if (err) return err; @@ -5798,8 +5789,7 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 arg, err = check_helper_mem_access(env, regno, meta->map_ptr->key_size, false, NULL); - } else if (base_type(arg_type) == ARG_PTR_TO_MAP_VALUE || - base_type(arg_type) == ARG_PTR_TO_UNINIT_MAP_VALUE) { + } else if (base_type(arg_type) == ARG_PTR_TO_MAP_VALUE) { if (type_may_be_null(arg_type) && register_is_null(reg)) return 0; @@ -5811,7 +5801,7 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 arg, verbose(env, "invalid map_ptr to access map->value\n"); return -EACCES; } - meta->raw_mode = (arg_type == ARG_PTR_TO_UNINIT_MAP_VALUE); + meta->raw_mode = arg_type & MEM_UNINIT; err = check_helper_mem_access(env, regno, meta->map_ptr->value_size, false, meta); @@ -5838,11 +5828,11 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 arg, return -EACCES; } else if (arg_type == ARG_PTR_TO_FUNC) { meta->subprogno = reg->subprogno; - } else if (arg_type_is_mem_ptr(arg_type)) { + } else if (base_type(arg_type) == ARG_PTR_TO_MEM) { /* The access to this pointer is only checked when we hit the * next is_mem_size argument below. */ - meta->raw_mode = (arg_type == ARG_PTR_TO_UNINIT_MEM); + meta->raw_mode = arg_type & MEM_UNINIT; } else if (arg_type_is_mem_size(arg_type)) { bool zero_size_allowed = (arg_type == ARG_CONST_SIZE_OR_ZERO); @@ -6189,10 +6179,8 @@ static bool check_raw_mode_ok(const struct bpf_func_proto *fn) static bool check_args_pair_invalid(enum bpf_arg_type arg_curr, enum bpf_arg_type arg_next) { - return (arg_type_is_mem_ptr(arg_curr) && - !arg_type_is_mem_size(arg_next)) || - (!arg_type_is_mem_ptr(arg_curr) && - arg_type_is_mem_size(arg_next)); + return (base_type(arg_curr) == ARG_PTR_TO_MEM) != + arg_type_is_mem_size(arg_next); } static bool check_arg_pair_ok(const struct bpf_func_proto *fn) @@ -6203,7 +6191,7 @@ static bool check_arg_pair_ok(const struct bpf_func_proto *fn) * helper function specification. */ if (arg_type_is_mem_size(fn->arg1_type) || - arg_type_is_mem_ptr(fn->arg5_type) || + base_type(fn->arg5_type) == ARG_PTR_TO_MEM || check_args_pair_invalid(fn->arg1_type, fn->arg2_type) || check_args_pair_invalid(fn->arg2_type, fn->arg3_type) || check_args_pair_invalid(fn->arg3_type, fn->arg4_type) ||