From patchwork Thu Nov 17 22:55:01 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kumar Kartikeya Dwivedi X-Patchwork-Id: 13047439 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 585EFC4332F for ; Thu, 17 Nov 2022 22:56:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234843AbiKQW4M (ORCPT ); Thu, 17 Nov 2022 17:56:12 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53542 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235006AbiKQW4K (ORCPT ); Thu, 17 Nov 2022 17:56:10 -0500 Received: from mail-pg1-x542.google.com (mail-pg1-x542.google.com [IPv6:2607:f8b0:4864:20::542]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AC276657F3 for ; Thu, 17 Nov 2022 14:56:09 -0800 (PST) Received: by mail-pg1-x542.google.com with SMTP id r18so3398481pgr.12 for ; Thu, 17 Nov 2022 14:56:09 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=++ULrfF8CmAP2xQVn0biv80cUJKxHLKHh12y4coOwaU=; b=m/9dLYPqUIDl56gmGLMERMYPtDrChkKkWcCCfbJiFmmx7UeRIZVrByWMCo26xpWpOz tXTbI97DzT6FXGUCmRHl3Kkncr+ucGW+UWFl0z7btepfTr8Bav9t54sLDkU6c3CMe/SZ 5NQp3pe5GL+TNCKiz1ksHnfIFiq1yiF5An7iEdkoKE6Y/6fV3q6Xef3BJKlYoIekxzdJ DBY9ZYUXG8Y1vHtxoIT0tQS9U/2+o35jvG1vBmFzBMwMyFP+O15W01Fovl0K1LrW3bNC zPXUslVm9+V2IG2zW1p33NBbJ+FSiXqzT9uqvv2PHbXmMrQA5QRTkKyfxxizTYUpmc+r Mrfg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=++ULrfF8CmAP2xQVn0biv80cUJKxHLKHh12y4coOwaU=; b=W82XAadG/hI0yl22/ql+qdzusJnKmI0+oKAbeCcVoAH0TgZ3w7yaiDjv4V2T/zgUKN aXI+Za+a7gMo/pmi1MAeU6oGws2yHlZV9vZmLFN8Ab/OVK3oe6WIeF0/IJXXfcqQbZVL E3N5cqQpz6ZeD3E6aHEx3cUcuvj3LnukHXcEv4ANYdoLqixFRI37a9EOhnTW/A2TbOEK RuK/OpW2XV3/ZwspuzFoxvUdgNv8Zb9iQNoKiPZyCRDJkEhirAiuyZeNYFkFILFLl+zx fV3S9cg26YjyQ206WP19KN33y8wcJAdmuQyhgW1sV/Ybk/K751dwELqftyPg09pJOdfP mWcw== X-Gm-Message-State: ANoB5pmd2joWpSYk6MIKgjpn4yDk+uJjxOxZh0ZnnEI9+lqgh0+nli/a mHWIErLuqM6Ig9pdcRBZo4f4CYtLRGY= X-Google-Smtp-Source: AA0mqf4anDXAwyMCqnidz7nRCJDwxHwEctZCLy4uLljbXnZECpb5BqiiQ9PohGi2Ql0bgnwTQNavaQ== X-Received: by 2002:a63:1760:0:b0:46f:9c0b:1e86 with SMTP id 32-20020a631760000000b0046f9c0b1e86mr3904530pgx.508.1668725768881; Thu, 17 Nov 2022 14:56:08 -0800 (PST) Received: from localhost ([2409:40f4:8:955c:5484:8048:c08:7b3]) by smtp.gmail.com with ESMTPSA id z11-20020aa7948b000000b0056262811c5fsm1706285pfk.59.2022.11.17.14.56.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 17 Nov 2022 14:56:08 -0800 (PST) From: Kumar Kartikeya Dwivedi To: bpf@vger.kernel.org Cc: Alexei Starovoitov , Andrii Nakryiko , Daniel Borkmann , Martin KaFai Lau , Dave Marchevsky Subject: [PATCH bpf-next v9 14/23] bpf: Introduce bpf_obj_drop Date: Fri, 18 Nov 2022 04:25:01 +0530 Message-Id: <20221117225510.1676785-15-memxor@gmail.com> X-Mailer: git-send-email 2.38.1 In-Reply-To: <20221117225510.1676785-1-memxor@gmail.com> References: <20221117225510.1676785-1-memxor@gmail.com> MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=7736; i=memxor@gmail.com; h=from:subject; bh=mZvoCqtK4h6DgMb78xDqGgfqpZU5R/RixAo8Aq5Ac4M=; b=owEBbQKS/ZANAwAIAUzgyIZIvxHKAcsmYgBjdrkcy5zIvV+rHl3HnRQRK/23jp1DhZbBL7igEk0m 7vRD9rCJAjMEAAEIAB0WIQRLvip+Buz51YI8YRFM4MiGSL8RygUCY3a5HAAKCRBM4MiGSL8RyjH6EA Cm3/rAN7TeRtHMaj4wav1xPRAzLmFMn4P6Ezf1CokgXN9lkD+pNdOA7Vfeyxm+RJyTYf+l7tpLYfJs UHw9lIG2cLWeoCQzYjsrtA28kAOCrZiqI/i1OdpbvKL7gENxMN8h9m8yp4b7DqhISCEbyOB1iDtoMJ adZatYCbByXyMgtd0pA6LUEjObH5eKEuR4YdWJ5CN+bqtREg8hpNIrMAoYS7rOLGAsxOl61vRWDsGB vTDevJ4pPXPp/AK/zDYXXaDPaUuczMeHxnvT794YoYWgqaqKGZoK4GyZLaSIW3iy2NuuJPshfb8DkE pARczDtltYevtk160rKScwpYjEs37r8EpH29VkQY6kg7MuOd2eK8cm2n+/3sKpjuTvLHdENp9Z7Ggf zahIP36nowViLTQZAuMVItHkIKCWLZa4QlNO7dkw5D2Y2bCsdbEonon7Z6be5OwMGqnlaQ04FENU/m N+Z9I/B1X8eVJuNTNrqLUn6lkEVTLoX+D2vk3KhHcFQSgmpgMO89tQzxa/1Z1ecMxOu0SuSovZ2P47 yzQWmSKr9hyqvO918Mj4dHwFAc3lDWqnM1bjoYs0RsbKbpvA7idQ0OxYLuFPtYqz1COVek8I7CYpl+ 36DShHnHjPpA1W1viLJBYBleVdg1RXEMwaVOJcnmHgVoRtgPoh7WoTkQDKCA== X-Developer-Key: i=memxor@gmail.com; a=openpgp; fpr=4BBE2A7E06ECF9D5823C61114CE0C88648BF11CA Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net Introduce bpf_obj_drop, which is the kfunc used to free allocated objects (allocated using bpf_obj_new). Pairing with bpf_obj_new, it implicitly destructs the fields part of object automatically without user intervention. Just like the previous patch, btf_struct_meta that is needed to free up the special fields is passed as a hidden argument to the kfunc. For the user, a convenience macro hides over the kernel side kfunc which is named bpf_obj_drop_impl. Continuing the previous example: void prog(void) { struct foo *f; f = bpf_obj_new(typeof(*f)); if (!f) return; bpf_obj_drop(f); } Signed-off-by: Kumar Kartikeya Dwivedi --- kernel/bpf/helpers.c | 11 ++++ kernel/bpf/verifier.c | 66 +++++++++++++++---- .../testing/selftests/bpf/bpf_experimental.h | 13 ++++ 3 files changed, 79 insertions(+), 11 deletions(-) diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index c4f1c22cc44c..71d803ca0c1d 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -1770,6 +1770,16 @@ void *bpf_obj_new_impl(u64 local_type_id__k, void *meta__ign) return p; } +void bpf_obj_drop_impl(void *p__alloc, void *meta__ign) +{ + struct btf_struct_meta *meta = meta__ign; + void *p = p__alloc; + + if (meta) + bpf_obj_free_fields(meta->record, p); + bpf_mem_free(&bpf_global_ma, p); +} + __diag_pop(); BTF_SET8_START(generic_btf_ids) @@ -1777,6 +1787,7 @@ BTF_SET8_START(generic_btf_ids) BTF_ID_FLAGS(func, crash_kexec, KF_DESTRUCTIVE) #endif BTF_ID_FLAGS(func, bpf_obj_new_impl, KF_ACQUIRE | KF_RET_NULL) +BTF_ID_FLAGS(func, bpf_obj_drop_impl, KF_RELEASE) BTF_SET8_END(generic_btf_ids) static const struct btf_kfunc_id_set generic_kfunc_set = { diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index ab91037df1c8..b96c525fa413 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -7878,6 +7878,10 @@ struct bpf_kfunc_call_arg_meta { u64 value; bool found; } arg_constant; + struct { + struct btf *btf; + u32 btf_id; + } arg_obj_drop; }; static bool is_kfunc_acquire(struct bpf_kfunc_call_arg_meta *meta) @@ -7956,6 +7960,11 @@ static bool is_kfunc_arg_ignore(const struct btf *btf, const struct btf_param *a return __kfunc_param_match_suffix(btf, arg, "__ign"); } +static bool is_kfunc_arg_alloc_obj(const struct btf *btf, const struct btf_param *arg) +{ + return __kfunc_param_match_suffix(btf, arg, "__alloc"); +} + static bool is_kfunc_arg_scalar_with_name(const struct btf *btf, const struct btf_param *arg, const char *name) @@ -8050,6 +8059,7 @@ static u32 *reg2btf_ids[__BPF_REG_TYPE_MAX] = { enum kfunc_ptr_arg_type { KF_ARG_PTR_TO_CTX, + KF_ARG_PTR_TO_ALLOC_BTF_ID, /* Allocated object */ KF_ARG_PTR_TO_KPTR, /* PTR_TO_KPTR but type specific */ KF_ARG_PTR_TO_DYNPTR, KF_ARG_PTR_TO_BTF_ID, /* Also covers reg2btf_ids conversions */ @@ -8057,6 +8067,20 @@ enum kfunc_ptr_arg_type { KF_ARG_PTR_TO_MEM_SIZE, /* Size derived from next argument, skip it */ }; +enum special_kfunc_type { + KF_bpf_obj_new_impl, + KF_bpf_obj_drop_impl, +}; + +BTF_SET_START(special_kfunc_set) +BTF_ID(func, bpf_obj_new_impl) +BTF_ID(func, bpf_obj_drop_impl) +BTF_SET_END(special_kfunc_set) + +BTF_ID_LIST(special_kfunc_list) +BTF_ID(func, bpf_obj_new_impl) +BTF_ID(func, bpf_obj_drop_impl) + static enum kfunc_ptr_arg_type get_kfunc_ptr_arg_type(struct bpf_verifier_env *env, struct bpf_kfunc_call_arg_meta *meta, @@ -8077,6 +8101,9 @@ get_kfunc_ptr_arg_type(struct bpf_verifier_env *env, if (btf_get_prog_ctx_type(&env->log, meta->btf, t, resolve_prog_type(env->prog), argno)) return KF_ARG_PTR_TO_CTX; + if (is_kfunc_arg_alloc_obj(meta->btf, &args[argno])) + return KF_ARG_PTR_TO_ALLOC_BTF_ID; + if (is_kfunc_arg_kptr_get(meta, argno)) { if (!btf_type_is_ptr(ref_t)) { verbose(env, "arg#0 BTF type must be a double pointer for kptr_get kfunc\n"); @@ -8293,6 +8320,7 @@ static int check_kfunc_args(struct bpf_verifier_env *env, struct bpf_kfunc_call_ return kf_arg_type; switch (kf_arg_type) { + case KF_ARG_PTR_TO_ALLOC_BTF_ID: case KF_ARG_PTR_TO_BTF_ID: if (!is_kfunc_trusted_args(meta)) break; @@ -8329,6 +8357,21 @@ static int check_kfunc_args(struct bpf_verifier_env *env, struct bpf_kfunc_call_ return -EINVAL; } break; + case KF_ARG_PTR_TO_ALLOC_BTF_ID: + if (reg->type != (PTR_TO_BTF_ID | MEM_ALLOC)) { + verbose(env, "arg#%d expected pointer to allocated object\n", i); + return -EINVAL; + } + if (!reg->ref_obj_id) { + verbose(env, "allocated object must be referenced\n"); + return -EINVAL; + } + if (meta->btf == btf_vmlinux && + meta->func_id == special_kfunc_list[KF_bpf_obj_drop_impl]) { + meta->arg_obj_drop.btf = reg->btf; + meta->arg_obj_drop.btf_id = reg->btf_id; + } + break; case KF_ARG_PTR_TO_KPTR: if (reg->type != PTR_TO_MAP_VALUE) { verbose(env, "arg#0 expected pointer to map value\n"); @@ -8399,17 +8442,6 @@ static int check_kfunc_args(struct bpf_verifier_env *env, struct bpf_kfunc_call_ return 0; } -enum special_kfunc_type { - KF_bpf_obj_new_impl, -}; - -BTF_SET_START(special_kfunc_set) -BTF_ID(func, bpf_obj_new_impl) -BTF_SET_END(special_kfunc_set) - -BTF_ID_LIST(special_kfunc_list) -BTF_ID(func, bpf_obj_new_impl) - static int check_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn, int *insn_idx_p) { @@ -8531,6 +8563,10 @@ static int check_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn, env->insn_aux_data[insn_idx].obj_new_size = ret_t->size; env->insn_aux_data[insn_idx].kptr_struct_meta = btf_find_struct_meta(ret_btf, ret_btf_id); + } else if (meta.func_id == special_kfunc_list[KF_bpf_obj_drop_impl]) { + env->insn_aux_data[insn_idx].kptr_struct_meta = + btf_find_struct_meta(meta.arg_obj_drop.btf, + meta.arg_obj_drop.btf_id); } else { verbose(env, "kernel function %s unhandled dynamic return type\n", meta.func_name); @@ -14767,6 +14803,14 @@ static int fixup_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn, insn_buf[2] = addr[1]; insn_buf[3] = *insn; *cnt = 4; + } else if (desc->func_id == special_kfunc_list[KF_bpf_obj_drop_impl]) { + struct btf_struct_meta *kptr_struct_meta = env->insn_aux_data[insn_idx].kptr_struct_meta; + struct bpf_insn addr[2] = { BPF_LD_IMM64(BPF_REG_2, (long)kptr_struct_meta) }; + + insn_buf[0] = addr[0]; + insn_buf[1] = addr[1]; + insn_buf[2] = *insn; + *cnt = 3; } return 0; } diff --git a/tools/testing/selftests/bpf/bpf_experimental.h b/tools/testing/selftests/bpf/bpf_experimental.h index aeb6a7fcb7c4..8473395a11af 100644 --- a/tools/testing/selftests/bpf/bpf_experimental.h +++ b/tools/testing/selftests/bpf/bpf_experimental.h @@ -22,4 +22,17 @@ extern void *bpf_obj_new_impl(__u64 local_type_id, void *meta) __ksym; /* Convenience macro to wrap over bpf_obj_new_impl */ #define bpf_obj_new(type) ((type *)bpf_obj_new_impl(bpf_core_type_id_local(type), NULL)) +/* Description + * Free an allocated object. All fields of the object that require + * destruction will be destructed before the storage is freed. + * + * The 'meta' parameter is a hidden argument that is ignored. + * Returns + * Void. + */ +extern void bpf_obj_drop_impl(void *kptr, void *meta) __ksym; + +/* Convenience macro to wrap over bpf_obj_drop_impl */ +#define bpf_obj_drop(kptr) bpf_obj_drop_impl(kptr, NULL) + #endif