From patchwork Wed Aug 31 16:54:36 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Roberto Sassu X-Patchwork-Id: 12961098 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 9F839C3DA6B for ; Wed, 31 Aug 2022 16:56:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232153AbiHaQ4i (ORCPT ); Wed, 31 Aug 2022 12:56:38 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60008 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229591AbiHaQ4U (ORCPT ); Wed, 31 Aug 2022 12:56:20 -0400 Received: from frasgout11.his.huawei.com (frasgout11.his.huawei.com [14.137.139.23]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3153FDC0AE; Wed, 31 Aug 2022 09:56:16 -0700 (PDT) Received: from mail02.huawei.com (unknown [172.18.147.228]) by frasgout11.his.huawei.com (SkyGuard) with ESMTP id 4MHqtZ2WXLz9xHvF; Thu, 1 Sep 2022 00:50:46 +0800 (CST) Received: from huaweicloud.com (unknown [10.204.63.22]) by APP2 (Coremail) with SMTP id GxC2BwBX0lxfkg9jJXIRAA--.5993S5; Wed, 31 Aug 2022 17:55:46 +0100 (CET) From: Roberto Sassu To: ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, martin.lau@linux.dev, song@kernel.org, yhs@fb.com, john.fastabend@gmail.com, kpsingh@kernel.org, sdf@google.com, haoluo@google.com, jolsa@kernel.org, mykolal@fb.com, dhowells@redhat.com, jarkko@kernel.org, rostedt@goodmis.org, mingo@redhat.com, paul@paul-moore.com, jmorris@namei.org, serge@hallyn.com, shuah@kernel.org Cc: bpf@vger.kernel.org, keyrings@vger.kernel.org, linux-security-module@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, deso@posteo.net, memxor@gmail.com, Roberto Sassu , Joanne Koong Subject: [PATCH v15 03/12] btf: Allow dynamic pointer parameters in kfuncs Date: Wed, 31 Aug 2022 18:54:36 +0200 Message-Id: <20220831165445.1071641-4-roberto.sassu@huaweicloud.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220831165445.1071641-1-roberto.sassu@huaweicloud.com> References: <20220831165445.1071641-1-roberto.sassu@huaweicloud.com> MIME-Version: 1.0 X-CM-TRANSID: GxC2BwBX0lxfkg9jJXIRAA--.5993S5 X-Coremail-Antispam: 1UD129KBjvJXoWxKrWDAF1fKw1DKr4DKrykKrg_yoW7ZFWkpF 4fC3s2vr4kJr4xuwnrAF45ArW5Kay0q347CrWrC34FyF17XryDXF1UKry8Z3sYkrWkC3Wx Ar1Fg3y5ua4xArJanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUPqb4IE77IF4wAFF20E14v26rWj6s0DM7CY07I20VC2zVCF04k2 6cxKx2IYs7xG6r1S6rWUM7CIcVAFz4kK6r1j6r18M28IrcIa0xkI8VA2jI8067AKxVWUWw A2048vs2IY020Ec7CjxVAFwI0_Xr0E3s1l8cAvFVAK0II2c7xJM28CjxkF64kEwVA0rcxS w2x7M28EF7xvwVC0I7IYx2IY67AKxVW8JVW5JwA2z4x0Y4vE2Ix0cI8IcVCY1x0267AKxV W8Jr0_Cr1UM28EF7xvwVC2z280aVAFwI0_Gr0_Cr1l84ACjcxK6I8E87Iv6xkF7I0E14v2 6r4UJVWxJr1le2I262IYc4CY6c8Ij28IcVAaY2xG8wAqx4xG64xvF2IEw4CE5I8CrVC2j2 WlYx0E2Ix0cI8IcVAFwI0_JrI_JrylYx0Ex4A2jsIE14v26r1j6r4UMcvjeVCFs4IE7xkE bVWUJVW8JwACjcxG0xvY0x0EwIxGrwACI402YVCY1x02628vn2kIc2xKxwCY1x0262kKe7 AKxVW8ZVWrXwCF04k20xvY0x0EwIxGrwCFx2IqxVCFs4IE7xkEbVWUJVW8JwC20s026c02 F40E14v26r1j6r18MI8I3I0E7480Y4vE14v26r106r1rMI8E67AF67kF1VAFwI0_GFv_Wr ylIxkGc2Ij64vIr41lIxAIcVC0I7IYx2IY67AKxVW8JVW5JwCI42IY6xIIjxv20xvEc7Cj xVAFwI0_Gr1j6F4UJwCI42IY6xAIw20EY4v20xvaj40_Jr0_JF4lIxAIcVC2z280aVAFwI 0_Gr0_Cr1lIxAIcVC2z280aVCY1x0267AKxVW8Jr0_Cr1UYxBIdaVFxhVjvjDU0xZFpf9x 07jzE__UUUUU= X-CM-SenderInfo: purev21wro2thvvxqx5xdzvxpfor3voofrz/1tbiAgABBF1jj357EwAAsg X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net From: Roberto Sassu Allow dynamic pointers (struct bpf_dynptr_kern *) to be specified as parameters in kfuncs. Also, ensure that dynamic pointers passed as argument are valid and initialized, are a pointer to the stack, and of the type local. More dynamic pointer types can be supported in the future. To properly detect whether a parameter is of the desired type, introduce the stringify_struct() macro to compare the returned structure name with the desired name. In addition, protect against structure renames, by halting the build with BUILD_BUG_ON(), so that developers have to revisit the code. To check if a dynamic pointer passed to the kfunc is valid and initialized, and if its type is local, export the existing functions is_dynptr_reg_valid_init() and is_dynptr_type_expected(). Cc: Joanne Koong Cc: Kumar Kartikeya Dwivedi Signed-off-by: Roberto Sassu --- include/linux/bpf_verifier.h | 5 +++++ include/linux/btf.h | 9 +++++++++ kernel/bpf/btf.c | 33 +++++++++++++++++++++++++++++++++ kernel/bpf/verifier.c | 10 +++++----- 4 files changed, 52 insertions(+), 5 deletions(-) diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h index 1fdddbf3546b..dd58dfccd025 100644 --- a/include/linux/bpf_verifier.h +++ b/include/linux/bpf_verifier.h @@ -571,6 +571,11 @@ int check_kfunc_mem_size_reg(struct bpf_verifier_env *env, struct bpf_reg_state u32 regno); int check_mem_reg(struct bpf_verifier_env *env, struct bpf_reg_state *reg, u32 regno, u32 mem_size); +bool is_dynptr_reg_valid_init(struct bpf_verifier_env *env, + struct bpf_reg_state *reg); +bool is_dynptr_type_expected(struct bpf_verifier_env *env, + struct bpf_reg_state *reg, + enum bpf_arg_type arg_type); /* this lives here instead of in bpf.h because it needs to dereference tgt_prog */ static inline u64 bpf_trampoline_compute_key(const struct bpf_prog *tgt_prog, diff --git a/include/linux/btf.h b/include/linux/btf.h index ad93c2d9cc1c..f546d368ac5d 100644 --- a/include/linux/btf.h +++ b/include/linux/btf.h @@ -52,6 +52,15 @@ #define KF_SLEEPABLE (1 << 5) /* kfunc may sleep */ #define KF_DESTRUCTIVE (1 << 6) /* kfunc performs destructive actions */ +/* + * Return the name of the passed struct, if exists, or halt the build if for + * example the structure gets renamed. In this way, developers have to revisit + * the code using that structure name, and update it accordingly. + */ +#define stringify_struct(x) \ + ({ BUILD_BUG_ON(sizeof(struct x) < 0); \ + __stringify(x); }) + struct btf; struct btf_member; struct btf_type; diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index e49b3b6d48ad..4266bff5fada 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -6362,15 +6362,20 @@ static int btf_check_func_arg_match(struct bpf_verifier_env *env, if (is_kfunc) { bool arg_mem_size = i + 1 < nargs && is_kfunc_arg_mem_size(btf, &args[i + 1], ®s[regno + 1]); + bool arg_dynptr = btf_type_is_struct(ref_t) && + !strcmp(ref_tname, + stringify_struct(bpf_dynptr_kern)); /* Permit pointer to mem, but only when argument * type is pointer to scalar, or struct composed * (recursively) of scalars. * When arg_mem_size is true, the pointer can be * void *. + * Also permit initialized local dynamic pointers. */ if (!btf_type_is_scalar(ref_t) && !__btf_type_is_scalar_struct(log, btf, ref_t, 0) && + !arg_dynptr && (arg_mem_size ? !btf_type_is_void(ref_t) : 1)) { bpf_log(log, "arg#%d pointer type %s %s must point to %sscalar, or struct with scalar\n", @@ -6378,6 +6383,34 @@ static int btf_check_func_arg_match(struct bpf_verifier_env *env, return -EINVAL; } + if (arg_dynptr) { + if (reg->type != PTR_TO_STACK) { + bpf_log(log, "arg#%d pointer type %s %s not to stack\n", + i, btf_type_str(ref_t), + ref_tname); + return -EINVAL; + } + + if (!is_dynptr_reg_valid_init(env, reg)) { + bpf_log(log, + "arg#%d pointer type %s %s must be valid and initialized\n", + i, btf_type_str(ref_t), + ref_tname); + return -EINVAL; + } + + if (!is_dynptr_type_expected(env, reg, + ARG_PTR_TO_DYNPTR | DYNPTR_TYPE_LOCAL)) { + bpf_log(log, + "arg#%d pointer type %s %s points to unsupported dynamic pointer type\n", + i, btf_type_str(ref_t), + ref_tname); + return -EINVAL; + } + + continue; + } + /* Check for mem, len pair */ if (arg_mem_size) { if (check_kfunc_mem_size_reg(env, ®s[regno + 1], regno + 1)) { diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index bebb64423acb..3ada6e63e2c9 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -779,8 +779,8 @@ static bool is_dynptr_reg_valid_uninit(struct bpf_verifier_env *env, struct bpf_ return true; } -static bool is_dynptr_reg_valid_init(struct bpf_verifier_env *env, - struct bpf_reg_state *reg) +bool is_dynptr_reg_valid_init(struct bpf_verifier_env *env, + struct bpf_reg_state *reg) { struct bpf_func_state *state = func(env, reg); int spi = get_spi(reg->off); @@ -799,9 +799,9 @@ static bool is_dynptr_reg_valid_init(struct bpf_verifier_env *env, return true; } -static bool is_dynptr_type_expected(struct bpf_verifier_env *env, - struct bpf_reg_state *reg, - enum bpf_arg_type arg_type) +bool is_dynptr_type_expected(struct bpf_verifier_env *env, + struct bpf_reg_state *reg, + enum bpf_arg_type arg_type) { struct bpf_func_state *state = func(env, reg); enum bpf_dynptr_type dynptr_type;