From patchwork Thu Apr 28 23:57:42 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Hao Luo X-Patchwork-Id: 567753 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 B37FBC433FE for ; Thu, 28 Apr 2022 23:59:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1353459AbiD2ACc (ORCPT ); Thu, 28 Apr 2022 20:02:32 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41588 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230353AbiD2ACc (ORCPT ); Thu, 28 Apr 2022 20:02:32 -0400 Received: from mail-yb1-xb49.google.com (mail-yb1-xb49.google.com [IPv6:2607:f8b0:4864:20::b49]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A3173A146B for ; Thu, 28 Apr 2022 16:59:15 -0700 (PDT) Received: by mail-yb1-xb49.google.com with SMTP id d134-20020a25e68c000000b006483b1adcc3so6002723ybh.11 for ; Thu, 28 Apr 2022 16:59:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=bwYMTHq83CYfDXJ/AFPHvHePsWWp/A3QUlLPKzabZZs=; b=eMAXmuTn7DzYyoNg6YdPkeNl1KjaiZzgckYs8cPqvP0aXdIEHLSwwFg1Md02oztwdO rI9PB/HqKcRcV3/ROBXzBdLlxLY9NEo1Y/cq7CVcXV2S88YWiXxxL282V7slL3T8/rvY W4XCXQamqxkH6DXod79WWOFbGtFpiaZSS3X2FxDXCSKhOREX2ddfQ1TGIw4BvLlxHAkZ rdmAcf6McqAx08O6UYol4ec41Y6A1pnybgFcfgaD4192vfU/S4MLwHP2btnYj8SRCC+d iLHPw115EqseKPyQi54NRw6bYHntZlhQzRgztCKPYujfZjLTINBNkY5JBIQn+STQh6uY kZlQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=bwYMTHq83CYfDXJ/AFPHvHePsWWp/A3QUlLPKzabZZs=; b=LVxRoeR4duUpGpd737HHbSpOsRA/NUqH+Lv8sms1G6Hy+4UrwaPpDXUUuDYoHFIm5i AIgtHJ2t3giO5v/itxFMc31WoOYI5S5c6G2yKHfuwDIweDebIxfMHjBhhjKZMtJzkbd9 PsszBdPm6sDLm2Z8UiDR0dBbraWtT6e765g1sJKis6wX4NevnTAjflNHbPZtQXY3fulE e1FBapWcjf89qefw6Hq0WiPWwVQLXK1w9kaGrc9fvdD9zMBqKz49QQQ/Jlwc/D2l19zN kM6cIy5R31Jsw0LfSKvm9ZTsd18OM3FdcZlavA2jmLibb0PoTq7X9px5KomwXChuqPqx KZqg== X-Gm-Message-State: AOAM5314hzeL9mxcXTqlhRa36kb6gv0rIRt4oDtvSu7JC8CEdz82kM7A Ylo6hkC7bdnIk8O3yirgOsfHPXTDWtU= X-Google-Smtp-Source: ABdhPJzuS+NgdpvYg4maQ3wHNoUzdeBoh+I97prQJb3uFYETiH0spX1gztJA3jBd7llR5F4oognTGnaotes= X-Received: from haoluo.svl.corp.google.com ([2620:15c:2cd:202:25cd:1665:36bc:f38e]) (user=haoluo job=sendgmr) by 2002:a05:6902:c8:b0:633:ee0c:bca2 with SMTP id i8-20020a05690200c800b00633ee0cbca2mr35521223ybs.82.1651190354883; Thu, 28 Apr 2022 16:59:14 -0700 (PDT) Date: Thu, 28 Apr 2022 16:57:42 -0700 In-Reply-To: <20220428235751.103203-1-haoluo@google.com> Message-Id: <20220428235751.103203-2-haoluo@google.com> Mime-Version: 1.0 References: <20220428235751.103203-1-haoluo@google.com> X-Mailer: git-send-email 2.36.0.464.gb9c8b46e94-goog Subject: [PATCH stable linux-5.15.y 01/10] bpf: Introduce composable reg, ret and arg types. From: Hao Luo To: Greg KH Cc: Alexei Starovoitov , Andrii Nakryiko , Daniel Borkmann , laura@labbott.name, Kumar Kartikeya Dwivedi , stable@vger.kernel.org, Hao Luo Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org commit d639b9d13a39cf15639cbe6e8b2c43eb60148a73 upstream. There are some common properties shared between bpf reg, ret and arg values. For instance, a value may be a NULL pointer, or a pointer to a read-only memory. Previously, to express these properties, enumeration was used. For example, in order to test whether a reg value can be NULL, reg_type_may_be_null() simply enumerates all types that are possibly NULL. The problem of this approach is that it's not scalable and causes a lot of duplication. These properties can be combined, for example, a type could be either MAYBE_NULL or RDONLY, or both. This patch series rewrites the layout of reg_type, arg_type and ret_type, so that common properties can be extracted and represented as composable flag. For example, one can write ARG_PTR_TO_MEM | PTR_MAYBE_NULL which is equivalent to the previous ARG_PTR_TO_MEM_OR_NULL The type ARG_PTR_TO_MEM are called "base type" in this patch. Base types can be extended with flags. A flag occupies the higher bits while base types sits in the lower bits. This patch in particular sets up a set of macro for this purpose. The following patches will rewrite arg_types, ret_types and reg_types respectively. Signed-off-by: Hao Luo Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20211217003152.48334-2-haoluo@google.com Cc: stable@vger.kernel.org # 5.15.x --- include/linux/bpf.h | 42 ++++++++++++++++++++++++++++++++++++ include/linux/bpf_verifier.h | 14 ++++++++++++ 2 files changed, 56 insertions(+) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 15b690a0cecb..864af1285d7f 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -293,6 +293,29 @@ bool bpf_map_meta_equal(const struct bpf_map *meta0, extern const struct bpf_map_ops bpf_map_offload_ops; +/* bpf_type_flag contains a set of flags that are applicable to the values of + * arg_type, ret_type and reg_type. For example, a pointer value may be null, + * or a memory is read-only. We classify types into two categories: base types + * and extended types. Extended types are base types combined with a type flag. + * + * Currently there are no more than 32 base types in arg_type, ret_type and + * reg_types. + */ +#define BPF_BASE_TYPE_BITS 8 + +enum bpf_type_flag { + /* PTR may be NULL. */ + PTR_MAYBE_NULL = BIT(0 + BPF_BASE_TYPE_BITS), + + __BPF_TYPE_LAST_FLAG = PTR_MAYBE_NULL, +}; + +/* Max number of base types. */ +#define BPF_BASE_TYPE_LIMIT (1UL << BPF_BASE_TYPE_BITS) + +/* Max number of all types. */ +#define BPF_TYPE_LIMIT (__BPF_TYPE_LAST_FLAG | (__BPF_TYPE_LAST_FLAG - 1)) + /* function argument constraints */ enum bpf_arg_type { ARG_DONTCARE = 0, /* unused argument in helper function */ @@ -339,7 +362,13 @@ enum bpf_arg_type { ARG_PTR_TO_CONST_STR, /* pointer to a null terminated read-only string */ ARG_PTR_TO_TIMER, /* pointer to bpf_timer */ __BPF_ARG_TYPE_MAX, + + /* 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. + */ + __BPF_ARG_TYPE_LIMIT = BPF_TYPE_LIMIT, }; +static_assert(__BPF_ARG_TYPE_MAX <= BPF_BASE_TYPE_LIMIT); /* type of values returned from helper functions */ enum bpf_return_type { @@ -355,7 +384,14 @@ enum bpf_return_type { RET_PTR_TO_MEM_OR_BTF_ID_OR_NULL, /* returns a pointer to a valid memory or a btf_id or NULL */ RET_PTR_TO_MEM_OR_BTF_ID, /* returns a pointer to a valid memory or a btf_id */ RET_PTR_TO_BTF_ID, /* returns a pointer to a btf_id */ + __BPF_RET_TYPE_MAX, + + /* 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. + */ + __BPF_RET_TYPE_LIMIT = BPF_TYPE_LIMIT, }; +static_assert(__BPF_RET_TYPE_MAX <= BPF_BASE_TYPE_LIMIT); /* eBPF function prototype used by verifier to allow BPF_CALLs from eBPF programs * to in-kernel helper functions and for adjusting imm32 field in BPF_CALL @@ -457,7 +493,13 @@ enum bpf_reg_type { PTR_TO_FUNC, /* reg points to a bpf program function */ PTR_TO_MAP_KEY, /* reg points to a map element key */ __BPF_REG_TYPE_MAX, + + /* 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. + */ + __BPF_REG_TYPE_LIMIT = BPF_TYPE_LIMIT, }; +static_assert(__BPF_REG_TYPE_MAX <= BPF_BASE_TYPE_LIMIT); /* The information passed from prog-specific *_is_valid_access * back to the verifier. diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h index 364550dd19c4..2e612f3fd385 100644 --- a/include/linux/bpf_verifier.h +++ b/include/linux/bpf_verifier.h @@ -535,4 +535,18 @@ int bpf_check_attach_target(struct bpf_verifier_log *log, u32 btf_id, struct bpf_attach_target_info *tgt_info); +#define BPF_BASE_TYPE_MASK GENMASK(BPF_BASE_TYPE_BITS - 1, 0) + +/* extract base type from bpf_{arg, return, reg}_type. */ +static inline u32 base_type(u32 type) +{ + return type & BPF_BASE_TYPE_MASK; +} + +/* extract flags from an extended type. See bpf_type_flag in bpf.h. */ +static inline u32 type_flag(u32 type) +{ + return type & ~BPF_BASE_TYPE_MASK; +} + #endif /* _LINUX_BPF_VERIFIER_H */