From patchwork Sun Mar 20 15:55:05 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: 12786558 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 E6FE1C433EF for ; Sun, 20 Mar 2022 15:55:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S245414AbiCTP5L (ORCPT ); Sun, 20 Mar 2022 11:57:11 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49774 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S245415AbiCTP5L (ORCPT ); Sun, 20 Mar 2022 11:57:11 -0400 Received: from mail-pg1-x541.google.com (mail-pg1-x541.google.com [IPv6:2607:f8b0:4864:20::541]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0290E54188 for ; Sun, 20 Mar 2022 08:55:48 -0700 (PDT) Received: by mail-pg1-x541.google.com with SMTP id s72so5952238pgc.5 for ; Sun, 20 Mar 2022 08:55:47 -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=A+lWQlMxi/mZTiYCtRYuguDDMp67YxOZJ1qDkZ0OBh8=; b=oRaGSaKjDfpxbaDRqk/vE6sLQpZXr3ezgxYdf7h6ZXqTQ0XaZLUi97NeKdClNKnSZB zI7VsQk2OTiSihOvAF5W1IEnO6K0GMQtTAaKLs+dq3ohVeuOqf29a5R42UR/LT95N1ky iPV5Ch3h+qcmNuFmfZPxQLOEGFLCjai2vym2EmILE0bJz7RAf+WP4f1wZT+HAF2edYdZ 8PR2eoqYzeH28tWqSxXQtnPrjqbanAFEzE7mnVvFYJS4vOEF66L12RkD2TzBU8WGcHAm 8eTloakgRh5mg/yhuCXWx/oJvjhhOB7pZsThUu2/UkCQ8SJ+qo3ShKBJuXvZcVGekqBo 92vw== 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=A+lWQlMxi/mZTiYCtRYuguDDMp67YxOZJ1qDkZ0OBh8=; b=nILwOewtj56Hq0vujg8GN3ykqjmKsvnYfMKpVpEkkI+/EZwafRDaX4Ycq/SRjcm4k0 gM0DsvzOrXNm61dDRq1wWerYFifxC78HANlYIS/ll8psXZSBRD2LcyQ3ELml8OSR8ufD heuk5+WlCPQlid1f0e7rHcOuqz5AvbxAjP4nIKGNEvhvoToU79b9ZByrIZbK1e6FJiIQ EF5lDVnigs9cwKacKks04mM+LU3qD4KR6dw1OPs0qs1E0ihsbr/uDYaTVrDn7lXCPA5h Zdox6UHiCjX1JIG6qfRQyVlJans06LohDw3wBLnkLr+e7DGWmdqjlZMmkzTHX35SOmt9 l8Xg== X-Gm-Message-State: AOAM532pXYmQ/HhJoG3mwRfmGFGpZ56zJnWM5GMUW7YWq/R/D9US0LA8 acQjwg7QlolMJk7MXurcqRcxIiH5w58= X-Google-Smtp-Source: ABdhPJybbP/o80PE1+gvMqqSmHJuorF/GjipK4PDd7hy4vvLuvLQxhZZ5G6oZ5EZjDw1umKx61QRVg== X-Received: by 2002:a63:1b5c:0:b0:382:76f4:c76b with SMTP id b28-20020a631b5c000000b0038276f4c76bmr1932550pgm.424.1647791747342; Sun, 20 Mar 2022 08:55:47 -0700 (PDT) Received: from localhost ([14.139.187.71]) by smtp.gmail.com with ESMTPSA id s25-20020a056a00179900b004f737ce5c1asm16026374pfg.73.2022.03.20.08.55.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 20 Mar 2022 08:55:47 -0700 (PDT) From: Kumar Kartikeya Dwivedi To: bpf@vger.kernel.org Cc: Alexei Starovoitov , Andrii Nakryiko , Daniel Borkmann , =?utf-8?q?Toke_H=C3=B8iland-J=C3=B8?= =?utf-8?q?rgensen?= , Jesper Dangaard Brouer Subject: [PATCH bpf-next v3 08/13] bpf: Populate pairs of btf_id and destructor kfunc in btf Date: Sun, 20 Mar 2022 21:25:05 +0530 Message-Id: <20220320155510.671497-9-memxor@gmail.com> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220320155510.671497-1-memxor@gmail.com> References: <20220320155510.671497-1-memxor@gmail.com> MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=6270; h=from:subject; bh=FkCsHbcLcIDitDm954nc+PDuaTQ8gUpPSBycv+UOwts=; b=owEBbQKS/ZANAwAIAUzgyIZIvxHKAcsmYgBiN00yXbHvchmFGmkgnxuQ5P88XiYVJq23dHsTM+fA jX28nRKJAjMEAAEIAB0WIQRLvip+Buz51YI8YRFM4MiGSL8RygUCYjdNMgAKCRBM4MiGSL8RylWjD/ 0QVMN+hgf12cRvKZjyPqplUgqizDr/QL+Vw8dLJj5/8SPv1urS/MNtLzSRafsQ7pBqv3Bp3XcHwNGq eTcgeYKn6n8uSZn/c2HlxV/i0cK0kIrrA5X0WlaPSdssvVx6+1fqPY4hLkx7WpcoknrAHJ0En375Du Mt+vF9Hxs7zGah+YSpq8snu+B5+iXxoLa4WOarbmT4Zh8QU7oNYdVh21rF++/DUENS9LKB36azlCnA v+CJZ5osbmcme8sJVrMtUfGTj5XdTC/7wDkSKVoaLIT7O1SOCwwPzNB1hAhOHvgo2ng+89byMAeTAK So3+T8q2IHNFxtmXlKvT5ar+030Huosnvo3kNkklYPLCecu0op1fuTUhmHz3LA31EJMPQgARiUPors V3xSXOsr7s+1Pv42yvZV5YZtWZw3w3n5tEJaJOkpwusGITUf6U/B9TvwT/gEkNb+75jEehQKUauPvX 6eF4ctpB/5lh0JSRNVSPqMcXnh2KKRDBPbEEx1XS3P0Ln/IhqwbKMS7q8HyEvK6RTMCKCpBQtMo3Gk blNliJnjrQUvcMT/lS/Scujclgahhqv+Vn+6ZhrXzpdT886Pk1FnJbgWhzAmVXSyZ8ci/A/eV4XT9s fdwV97RcQe5U3O7MYplv1gHKI9/PrDgFagEhvsCny/IbT497F5bsC5TLyiKg== 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 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 e36ad26a5a6e..9cb6f61a50a7 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); @@ -7018,6 +7036,96 @@ 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