From patchwork Sat Dec 17 08:25:02 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dave Marchevsky X-Patchwork-Id: 13075797 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 559E2C4332F for ; Sat, 17 Dec 2022 08:25:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230091AbiLQIZj (ORCPT ); Sat, 17 Dec 2022 03:25:39 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39962 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230104AbiLQIZh (ORCPT ); Sat, 17 Dec 2022 03:25:37 -0500 Received: from mx0b-00082601.pphosted.com (mx0b-00082601.pphosted.com [67.231.153.30]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6EA242F671 for ; Sat, 17 Dec 2022 00:25:36 -0800 (PST) Received: from pps.filterd (m0148460.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.17.1.19/8.17.1.19) with ESMTP id 2BH8AtnX016989 for ; Sat, 17 Dec 2022 00:25:35 -0800 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fb.com; h=from : to : cc : subject : date : message-id : in-reply-to : references : mime-version : content-transfer-encoding : content-type; s=facebook; bh=X6QIxuBCdTRY1bch+Ed/moZM2DYJEUF9D41qa43guC8=; b=CaaTXu/QDK4kmZ8D2RUbbM3BiUWMWvlNyTCAnsrvMka9Lw+dsqi04Ou9qJNU5TbcI3uE znbyrHJy+PB1rhv8A74eVzzv4975awXCRgdEHb3ACgywKnKxV3TElfe9rEnk+YszvqK5 U/1x9E+Kl1ijeIfOgnL2xDxVsPiSqIHLOKE= Received: from mail.thefacebook.com ([163.114.132.120]) by mx0a-00082601.pphosted.com (PPS) with ESMTPS id 3mh6uj8mp8-2 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Sat, 17 Dec 2022 00:25:35 -0800 Received: from twshared15216.17.frc2.facebook.com (2620:10d:c085:108::8) by mail.thefacebook.com (2620:10d:c085:11d::7) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.34; Sat, 17 Dec 2022 00:25:33 -0800 Received: by devbig077.ldc1.facebook.com (Postfix, from userid 158236) id D844412A9E026; Sat, 17 Dec 2022 00:25:18 -0800 (PST) From: Dave Marchevsky To: CC: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Kernel Team , Kumar Kartikeya Dwivedi , Tejun Heo , Dave Marchevsky Subject: [PATCH v2 bpf-next 09/13] bpf: Special verifier handling for bpf_rbtree_{remove, first} Date: Sat, 17 Dec 2022 00:25:02 -0800 Message-ID: <20221217082506.1570898-10-davemarchevsky@fb.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20221217082506.1570898-1-davemarchevsky@fb.com> References: <20221217082506.1570898-1-davemarchevsky@fb.com> MIME-Version: 1.0 X-FB-Internal: Safe X-Proofpoint-ORIG-GUID: vvuLxH8FWvEzrHbxLSLNFy0wzTWbE91y X-Proofpoint-GUID: vvuLxH8FWvEzrHbxLSLNFy0wzTWbE91y X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.923,Hydra:6.0.545,FMLib:17.11.122.1 definitions=2022-12-17_03,2022-12-15_02,2022-06-22_01 Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net Newly-added bpf_rbtree_{remove,first} kfuncs have some special properties that require handling in the verifier: * both bpf_rbtree_remove and bpf_rbtree_first return the type containing the bpf_rb_node field, with the offset set to that field's offset, instead of a struct bpf_rb_node * * mark_reg_graph_node helper added in previous patch generalizes this logic, use it * bpf_rbtree_remove's node input is a node that's been inserted in the tree - a non-owning reference. * bpf_rbtree_remove must invalidate non-owning references in order to avoid aliasing issue. Add KF_INVALIDATE_NON_OWN flag, which indicates that the marked kfunc is a non-owning ref invalidation point, and associated verifier logic using previously-added invalidate_non_owning_refs helper. * Unlike other functions, which convert one of their input arg regs to non-owning reference, bpf_rbtree_first takes no arguments and just returns a non-owning reference (possibly null) * For now verifier logic for this is special-cased instead of adding new kfunc flag. This patch, along with the previous one, complete special verifier handling for all rbtree API functions added in this series. Signed-off-by: Dave Marchevsky --- include/linux/btf.h | 1 + kernel/bpf/helpers.c | 2 +- kernel/bpf/verifier.c | 34 ++++++++++++++++++++++++++++------ 3 files changed, 30 insertions(+), 7 deletions(-) diff --git a/include/linux/btf.h b/include/linux/btf.h index 8aee3f7f4248..3663911bb7c0 100644 --- a/include/linux/btf.h +++ b/include/linux/btf.h @@ -72,6 +72,7 @@ #define KF_DESTRUCTIVE (1 << 6) /* kfunc performs destructive actions */ #define KF_RCU (1 << 7) /* kfunc only takes rcu pointer arguments */ #define KF_RELEASE_NON_OWN (1 << 8) /* kfunc converts its referenced arg into non-owning ref */ +#define KF_INVALIDATE_NON_OWN (1 << 9) /* kfunc invalidates non-owning refs after return */ /* * Return the name of the passed struct, if exists, or halt the build if for diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index de4523c777b7..0e6d010e6423 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -2121,7 +2121,7 @@ BTF_ID_FLAGS(func, bpf_task_acquire, KF_ACQUIRE | KF_TRUSTED_ARGS) BTF_ID_FLAGS(func, bpf_task_acquire_not_zero, KF_ACQUIRE | KF_RCU | KF_RET_NULL) BTF_ID_FLAGS(func, bpf_task_kptr_get, KF_ACQUIRE | KF_KPTR_GET | KF_RET_NULL) BTF_ID_FLAGS(func, bpf_task_release, KF_RELEASE) -BTF_ID_FLAGS(func, bpf_rbtree_remove, KF_ACQUIRE) +BTF_ID_FLAGS(func, bpf_rbtree_remove, KF_ACQUIRE | KF_INVALIDATE_NON_OWN) BTF_ID_FLAGS(func, bpf_rbtree_add, KF_RELEASE | KF_RELEASE_NON_OWN) BTF_ID_FLAGS(func, bpf_rbtree_first, KF_RET_NULL) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 75979f78399d..b4bf3701de7f 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -8393,6 +8393,11 @@ static bool is_kfunc_release_non_own(struct bpf_kfunc_call_arg_meta *meta) return meta->kfunc_flags & KF_RELEASE_NON_OWN; } +static bool is_kfunc_invalidate_non_own(struct bpf_kfunc_call_arg_meta *meta) +{ + return meta->kfunc_flags & KF_INVALIDATE_NON_OWN; +} + static bool is_kfunc_trusted_args(struct bpf_kfunc_call_arg_meta *meta) { return meta->kfunc_flags & KF_TRUSTED_ARGS; @@ -9425,10 +9430,20 @@ static int check_kfunc_args(struct bpf_verifier_env *env, struct bpf_kfunc_call_ verbose(env, "arg#%d expected pointer to allocated object\n", i); return -EINVAL; } - if (!reg->ref_obj_id) { + if (meta->func_id == special_kfunc_list[KF_bpf_rbtree_remove]) { + if (reg->ref_obj_id) { + verbose(env, "rbtree_remove node input must be non-owning ref\n"); + return -EINVAL; + } + if (in_rbtree_lock_required_cb(env)) { + verbose(env, "rbtree_remove not allowed in rbtree cb\n"); + return -EINVAL; + } + } else if (!reg->ref_obj_id) { verbose(env, "allocated object must be referenced\n"); return -EINVAL; } + ret = process_kf_arg_ptr_to_rbtree_node(env, reg, regno, meta); if (ret < 0) return ret; @@ -9665,11 +9680,12 @@ static int check_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn, meta.func_id == special_kfunc_list[KF_bpf_list_pop_back]) { struct btf_field *field = meta.arg_list_head.field; - mark_reg_known_zero(env, regs, BPF_REG_0); - regs[BPF_REG_0].type = PTR_TO_BTF_ID | MEM_ALLOC; - regs[BPF_REG_0].btf = field->graph_root.btf; - regs[BPF_REG_0].btf_id = field->graph_root.value_btf_id; - regs[BPF_REG_0].off = field->graph_root.node_offset; + mark_reg_graph_node(regs, BPF_REG_0, &field->graph_root); + } else if (meta.func_id == special_kfunc_list[KF_bpf_rbtree_remove] || + meta.func_id == special_kfunc_list[KF_bpf_rbtree_first]) { + struct btf_field *field = meta.arg_rbtree_root.field; + + mark_reg_graph_node(regs, BPF_REG_0, &field->graph_root); } else if (meta.func_id == special_kfunc_list[KF_bpf_cast_to_kern_ctx]) { mark_reg_known_zero(env, regs, BPF_REG_0); regs[BPF_REG_0].type = PTR_TO_BTF_ID | PTR_TRUSTED; @@ -9735,7 +9751,13 @@ static int check_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn, if (is_kfunc_ret_null(&meta)) regs[BPF_REG_0].id = id; regs[BPF_REG_0].ref_obj_id = id; + } else if (meta.func_id == special_kfunc_list[KF_bpf_rbtree_first]) { + ref_set_non_owning_lock(env, ®s[BPF_REG_0]); } + + if (is_kfunc_invalidate_non_own(&meta)) + invalidate_non_owning_refs(env, &env->cur_state->active_lock); + if (reg_may_point_to_spin_lock(®s[BPF_REG_0]) && !regs[BPF_REG_0].id) regs[BPF_REG_0].id = ++env->id_gen; } /* else { add_kfunc_call() ensures it is btf_type_is_void(t) } */