From mboxrd@z Thu Jan 1 00:00:00 1970 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 8D124C433EF for ; Thu, 17 Mar 2022 12:00:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233324AbiCQMCG (ORCPT ); Thu, 17 Mar 2022 08:02:06 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50502 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233311AbiCQMCE (ORCPT ); Thu, 17 Mar 2022 08:02:04 -0400 Received: from mail-pj1-x1042.google.com (mail-pj1-x1042.google.com [IPv6:2607:f8b0:4864:20::1042]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0EF78182DB6 for ; Thu, 17 Mar 2022 05:00:47 -0700 (PDT) Received: by mail-pj1-x1042.google.com with SMTP id kx13-20020a17090b228d00b001c6715c9847so2946673pjb.1 for ; Thu, 17 Mar 2022 05:00:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=xjngzZSJ1NJj0Uuwv7x/SiLTjkcymSmxCdtUb26fsI8=; b=lUmzOWyPMJdnyV6r2KFsoTdkjYzCl9HPzEenHT+Sb61ekI1Zv8Dg65khlMNyIakdCC nTg3XwrR0kmjrWdc3EiGr/4StjBROp1iPnFGKJjF8AT9H/M5aQ//bTqeG8fe1kWomUu9 pH8OimeDsn/PT/FEYLaFpR/Fi6YeRrTxWDevVLny4HpqGnBVbL6kNFptNy+XNRYyl6N+ ClE/fY1rzD5oCCDRxQFJuJKeOr2YkyAhbzKN0CIGnDOK4e9Nx6UhWH6Vx6x9boRAzcRq QhJMm1W0fIL2xLbULp9rGzdonPBXJN9uqur2psw4Lx8tVKu0ycQs19JSKcE0lt56dDNk m8LA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=xjngzZSJ1NJj0Uuwv7x/SiLTjkcymSmxCdtUb26fsI8=; b=CP2FiiHkkC9mbLFJr7hzNwfpdd/CiEeQSXReAbHUG0B+rCAQR+vzxHr0BbC4zuFjsi UzAgVev0ezl/aydzR7F5h0DMVWgh65v+cIHvEc/W5p/xD2uFxQYGHG+kQ+ddUUiOymdi gVl8iIErbMsAL+9GUPC5dQmYlaA6JN25J46ZUbsSRNvpsia/A4E8gxMaYhGV6oOtNeqK 9oUZ5bnQi2W3ZM1WTzmYri1qlfEKHyfDuWjsTkOSVrQsaBD9cUhjIfkShgMLyfoDl2qh fHth3aQFO4So8cSypfTSOXptJTr8y7cW68RdsYJlHGAGwVPzzyxwo82nAsy+kr8m1iwf /KLg== X-Gm-Message-State: AOAM5335LrFvY7sSQ6JnHlavEUlqVcu42PGMf0nkhAj6PQA403+nU9Q4 ZI64lWEyFKd1G5BozLCKCTVZoKPhZCA= X-Google-Smtp-Source: ABdhPJzV//r34TrcxHekeq+iZWoGouVLfCWtZqfTYtpONvQd4zSJFVjOyBKh9QvzKppMoHqpEFp7QA== X-Received: by 2002:a17:90b:3909:b0:1c6:4909:1925 with SMTP id ob9-20020a17090b390900b001c649091925mr12555013pjb.202.1647518446951; Thu, 17 Mar 2022 05:00:46 -0700 (PDT) Received: from localhost ([157.51.20.101]) by smtp.gmail.com with ESMTPSA id a32-20020a631a20000000b003756899829csm5143457pga.58.2022.03.17.05.00.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 17 Mar 2022 05:00:46 -0700 (PDT) From: Kumar Kartikeya Dwivedi To: bpf@vger.kernel.org Cc: Alexei Starovoitov , Andrii Nakryiko , Daniel Borkmann , =?UTF-8?q?Toke=20H=C3=B8iland-J=C3=B8rgensen?= , Jesper Dangaard Brouer Subject: [PATCH bpf-next v2 10/15] bpf: Populate pairs of btf_id and destructor kfunc in btf Date: Thu, 17 Mar 2022 17:29:52 +0530 Message-Id: <20220317115957.3193097-11-memxor@gmail.com> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220317115957.3193097-1-memxor@gmail.com> References: <20220317115957.3193097-1-memxor@gmail.com> MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=6270; h=from:subject; bh=l6wYToCRPrkg6N43IEvVCSaFD2efxBOEmEbLYsDq94A=; b=owEBbQKS/ZANAwAIAUzgyIZIvxHKAcsmYgBiMyKjSPIYGjR78WYCjZEE6MOsfAKPQ4Lja24Cc1Q+ gNY7hzSJAjMEAAEIAB0WIQRLvip+Buz51YI8YRFM4MiGSL8RygUCYjMiowAKCRBM4MiGSL8RypjQD/ 9FeOD5gmryHIw+K2xemnHQgAvtlJYQSfMQeYEjD7A3kZsgVmF2BOQnmmRqo2TKBmDXBlGBDx4LJASB vLGPF9rsqjzlLSlO8fFmnTv87Pobbnm9Y3AHO4sntdCFZcAlMnVv3VFVCnYXN2Hpl1eqiDCXHuTFmo LB9DwvMqigCTUTaakbVMShcEoCVFQQK0I7+FoMqSe4X/sraEjjhOKMQEU3noG5MoZzVrG2kZKU2KXQ k9WbeAQWEGTsLODul8x/FTvnB5sc2vDafR9s+9hHT1Pbtqw76w007TbZX1jpo30DDsgwstfzkUDHYB CyyMIwMOBFXu9YjsZNldvJR66uXzfrHFe3w0glincowwJ0qw/2Yex+Lectetj05rkYkrAO2LAujK7W FBd1Eiy1SLEV9d7YUaEuOuTTs9cseyO05efrtD7acXSc5T8WBOMnjhzTlc7jbjai8RKvCowTj71W3g AyaGi7cFn+n8uZjDVO4doiTaOCnK0GnyPQqhJ2JgcUr7tjojaGj5vZK1fbi7cMvMc9JmRrrGtrqRfC XQc/H8Jr2EWP35JwQgeHbovW1RuLaEL/1L1NN4cjb3Wnlld7v6TK6CpNXDYV9pTNiW6CZlGZVNgoty SMmamMgE58W6IJxBx2FTqy4IUlKCY2FHCMorpZPgdsPx1+zC2wGgN2anTBYw== X-Developer-Key: i=memxor@gmail.com; a=openpgp; fpr=4BBE2A7E06ECF9D5823C61114CE0C88648BF11CA Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org To support storing referenced PTR_TO_BTF_ID in maps, we require associating a specific BTF ID with a 'destructor' kfunc. This is because we need to release a live referenced pointer at a certain offset in map value from the map destruction path, otherwise we end up leaking resources. Hence, introduce support for passing an array of btf_id, kfunc_btf_id pairs that denote a BTF ID and its associated release function. Then, add an accessor 'btf_find_dtor_kfunc' which can be used to look up the destructor kfunc of a certain BTF ID. If found, we can use it to free the object from the map free path. The registration of these pairs also serve as a whitelist of structures which are allowed as referenced PTR_TO_BTF_ID in a BPF map, because without finding the destructor kfunc, we will bail and return an error. Signed-off-by: Kumar Kartikeya Dwivedi --- include/linux/btf.h | 17 +++++++ kernel/bpf/btf.c | 108 ++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 125 insertions(+) diff --git a/include/linux/btf.h b/include/linux/btf.h index 5b578dc81c04..ff4be49b7a26 100644 --- a/include/linux/btf.h +++ b/include/linux/btf.h @@ -40,6 +40,11 @@ struct btf_kfunc_id_set { }; }; +struct btf_id_dtor_kfunc { + u32 btf_id; + u32 kfunc_btf_id; +}; + extern const struct file_operations btf_fops; void btf_get(struct btf *btf); @@ -346,6 +351,9 @@ bool btf_kfunc_id_set_contains(const struct btf *btf, enum btf_kfunc_type type, u32 kfunc_btf_id); int register_btf_kfunc_id_set(enum bpf_prog_type prog_type, const struct btf_kfunc_id_set *s); +s32 btf_find_dtor_kfunc(struct btf *btf, u32 btf_id); +int register_btf_id_dtor_kfuncs(const struct btf_id_dtor_kfunc *dtors, u32 add_cnt, + struct module *owner); #else static inline const struct btf_type *btf_type_by_id(const struct btf *btf, u32 type_id) @@ -369,6 +377,15 @@ static inline int register_btf_kfunc_id_set(enum bpf_prog_type prog_type, { return 0; } +static inline s32 btf_find_dtor_kfunc(struct btf *btf, u32 btf_id) +{ + return -ENOENT; +} +static inline int register_btf_id_dtor_kfuncs(const struct btf_id_dtor_kfunc *dtors, + u32 add_cnt, struct module *owner) +{ + return 0; +} #endif #endif diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index 2e51b391b684..275db109a470 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -207,12 +207,18 @@ enum btf_kfunc_hook { enum { BTF_KFUNC_SET_MAX_CNT = 32, + BTF_DTOR_KFUNC_MAX_CNT = 256, }; struct btf_kfunc_set_tab { struct btf_id_set *sets[BTF_KFUNC_HOOK_MAX][BTF_KFUNC_TYPE_MAX]; }; +struct btf_id_dtor_kfunc_tab { + u32 cnt; + struct btf_id_dtor_kfunc dtors[]; +}; + struct btf { void *data; struct btf_type **types; @@ -228,6 +234,7 @@ struct btf { u32 id; struct rcu_head rcu; struct btf_kfunc_set_tab *kfunc_set_tab; + struct btf_id_dtor_kfunc_tab *dtor_kfunc_tab; /* split BTF support */ struct btf *base_btf; @@ -1614,8 +1621,19 @@ static void btf_free_kfunc_set_tab(struct btf *btf) btf->kfunc_set_tab = NULL; } +static void btf_free_dtor_kfunc_tab(struct btf *btf) +{ + struct btf_id_dtor_kfunc_tab *tab = btf->dtor_kfunc_tab; + + if (!tab) + return; + kfree(tab); + btf->dtor_kfunc_tab = NULL; +} + static void btf_free(struct btf *btf) { + btf_free_dtor_kfunc_tab(btf); btf_free_kfunc_set_tab(btf); kvfree(btf->types); kvfree(btf->resolved_sizes); @@ -7026,6 +7044,96 @@ int register_btf_kfunc_id_set(enum bpf_prog_type prog_type, } EXPORT_SYMBOL_GPL(register_btf_kfunc_id_set); +s32 btf_find_dtor_kfunc(struct btf *btf, u32 btf_id) +{ + struct btf_id_dtor_kfunc_tab *tab = btf->dtor_kfunc_tab; + struct btf_id_dtor_kfunc *dtor; + + if (!tab) + return -ENOENT; + /* Even though the size of tab->dtors[0] is > sizeof(u32), we only need + * to compare the first u32 with btf_id, so we can reuse btf_id_cmp_func. + */ + BUILD_BUG_ON(offsetof(struct btf_id_dtor_kfunc, btf_id) != 0); + dtor = bsearch(&btf_id, tab->dtors, tab->cnt, sizeof(tab->dtors[0]), btf_id_cmp_func); + if (!dtor) + return -ENOENT; + return dtor->kfunc_btf_id; +} + +/* This function must be invoked only from initcalls/module init functions */ +int register_btf_id_dtor_kfuncs(const struct btf_id_dtor_kfunc *dtors, u32 add_cnt, + struct module *owner) +{ + struct btf_id_dtor_kfunc_tab *tab; + struct btf *btf; + u32 tab_cnt; + int ret; + + btf = btf_get_module_btf(owner); + if (!btf) { + if (!owner && IS_ENABLED(CONFIG_DEBUG_INFO_BTF)) { + pr_err("missing vmlinux BTF, cannot register dtor kfuncs\n"); + return -ENOENT; + } + if (owner && IS_ENABLED(CONFIG_DEBUG_INFO_BTF_MODULES)) { + pr_err("missing module BTF, cannot register dtor kfuncs\n"); + return -ENOENT; + } + return 0; + } + if (IS_ERR(btf)) + return PTR_ERR(btf); + + if (add_cnt >= BTF_DTOR_KFUNC_MAX_CNT) { + pr_err("cannot register more than %d kfunc destructors\n", BTF_DTOR_KFUNC_MAX_CNT); + ret = -E2BIG; + goto end; + } + + tab = btf->dtor_kfunc_tab; + /* Only one call allowed for modules */ + if (WARN_ON_ONCE(tab && btf_is_module(btf))) { + ret = -EINVAL; + goto end; + } + + tab_cnt = tab ? tab->cnt : 0; + if (tab_cnt > U32_MAX - add_cnt) { + ret = -EOVERFLOW; + goto end; + } + if (tab_cnt + add_cnt >= BTF_DTOR_KFUNC_MAX_CNT) { + pr_err("cannot register more than %d kfunc destructors\n", BTF_DTOR_KFUNC_MAX_CNT); + ret = -E2BIG; + goto end; + } + + tab = krealloc(btf->dtor_kfunc_tab, + offsetof(struct btf_id_dtor_kfunc_tab, dtors[tab_cnt + add_cnt]), + GFP_KERNEL | __GFP_NOWARN); + if (!tab) { + ret = -ENOMEM; + goto end; + } + + if (!btf->dtor_kfunc_tab) + tab->cnt = 0; + btf->dtor_kfunc_tab = tab; + + memcpy(tab->dtors + tab->cnt, dtors, add_cnt * sizeof(tab->dtors[0])); + tab->cnt += add_cnt; + + sort(tab->dtors, tab->cnt, sizeof(tab->dtors[0]), btf_id_cmp_func, NULL); + + return 0; +end: + btf_free_dtor_kfunc_tab(btf); + btf_put(btf); + return ret; +} +EXPORT_SYMBOL_GPL(register_btf_id_dtor_kfuncs); + #define MAX_TYPES_ARE_COMPAT_DEPTH 2 static -- 2.35.1