From patchwork Sat Apr 9 09:32:58 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: 12807793 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 D3CABC433F5 for ; Sat, 9 Apr 2022 09:33:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234967AbiDIJfe (ORCPT ); Sat, 9 Apr 2022 05:35:34 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50424 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229964AbiDIJfd (ORCPT ); Sat, 9 Apr 2022 05:35:33 -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 1C1E262CC for ; Sat, 9 Apr 2022 02:33:27 -0700 (PDT) Received: by mail-pg1-x541.google.com with SMTP id t13so9846521pgn.8 for ; Sat, 09 Apr 2022 02:33:27 -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=XeHmYgHw7UI5yCAngCSiEUhj4Wa74RE1CCwgygy8rm4=; b=L6yqQhTwB/sUOg61iTS58q/Z8LWmukkDtJSxdgCjWcYTQ+almT9hEpoeFmCtO792qq kdpA/1o8vSdsOfVKpehOMvT0LVeTJMVMX+R+N7opigvgPRDUGPhwbXVOmuzkzOHSUe5W pq7elpV9O8VHa0A7xbkohRkfDFJJOQSDBy/0sInR6oyG3+FO0SIly2J9Y0g97PlRtWYI h1RuTdB8ziosydP3iubYFTNL7zoDlGLvYAQ+ABCxXqKsdY3GAijC+47Y0z/VVfd/KOII RYFHyxu9dypvoSwtzN6CKJFDbBZw3F6xB/hlBRIawTnC0mk2qyEH2PDkSNGpw/JMRIEH xxUA== 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=XeHmYgHw7UI5yCAngCSiEUhj4Wa74RE1CCwgygy8rm4=; b=gavLux7ydBjZ6MTSTDTQ3rH34QiYeQok/rtL4kGhYsAn4P+Bzkk0RdieFb0lx5P5Ty hN7OIRWIstHnDkymrpEhwWYPVuFl2HXeKLxQ5x2n1J4hrTGeqVu4ClCS1QVcqYO1okRo oEPGYdkctUCjjAg6uU09zBoOUJ/Zz/ewC5lGPjhxVuHPllmHVrMqJCatJsH3ebx2H0Qi FuzeF2cBxpK+T/vH06/JWcHggjsOVCDqwI0O5eFiOqHXP8x5Bz4PNDCAzCzLXtChTefe 0nEXWeT4s8LjGxgpIvvdS8Bz9opXU9YXmHX9WIA+o5ajJB6ifETRElLra0/RcOn4vcMI PlIA== X-Gm-Message-State: AOAM531scc/zho3Cfi8D9OUIVVoKOf+UslF9Kst5fvpb8TQvMrCfmnGL AM9sIheki4hYMyv5R0hk0V7YyTqNwg4= X-Google-Smtp-Source: ABdhPJyXjH4hPLIpfKvVdJ4/bOlIjQSDSsWNMQY6K42rX5wS3rLtQkNzOuesbWbZahpSG/HAPxWLCA== X-Received: by 2002:a63:eb13:0:b0:382:1cd5:7d06 with SMTP id t19-20020a63eb13000000b003821cd57d06mr19040726pgh.280.1649496806465; Sat, 09 Apr 2022 02:33:26 -0700 (PDT) Received: from localhost ([112.79.142.148]) by smtp.gmail.com with ESMTPSA id z16-20020a637e10000000b00382b21c6b0bsm23830684pgc.51.2022.04.09.02.33.25 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 09 Apr 2022 02:33:26 -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 v4 08/13] bpf: Populate pairs of btf_id and destructor kfunc in btf Date: Sat, 9 Apr 2022 15:02:58 +0530 Message-Id: <20220409093303.499196-9-memxor@gmail.com> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220409093303.499196-1-memxor@gmail.com> References: <20220409093303.499196-1-memxor@gmail.com> MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=6270; h=from:subject; bh=5b2+P5YwO4457lAKU+5emkQKpLhzD4O4e8iSQTv41ow=; b=owEBbQKS/ZANAwAIAUzgyIZIvxHKAcsmYgBiUVF0XuEFPX9mh1gBTnJGOWYWsf9gmqbm8fWa8iJh 9Cqn/h+JAjMEAAEIAB0WIQRLvip+Buz51YI8YRFM4MiGSL8RygUCYlFRdAAKCRBM4MiGSL8RyoefEA C/wpm/LmyZUHpJaVHB3YoM4YLfrF4syWe/S4EaEW7lNOGRUt/+qHSGJpA1uo94lubPAupM2qWoZptv AEEP2J3rKxGefTKBvWvObFl9yMNyPtREhYn0ywrJYrkkaGZwYB1aCaGR//HWmmKAgZfwFfzbP2DqAd dAkP17REVkQsDWA4Jq91WYmBDG1iHi7tpk1hyKpBrkPzVKoxFC76D71Qbigh8Ws0ssS86RoUqQYNN5 rTkSyhikxwtfmkwTXPI8txHnvDbwLDJLTI2oHAqZsb8ym2sU9eT4eLcnF7NbTQ0RG5+Te12NIe3acI n8IoXyIg6am0MTI4EK6f9RBZS25gLj0iswDDS+NbaLUKlKzWzeI/fi5tMRTP3f3VACf5pMkgyCrAPo SJu3oZ0rlukDB/vGOLaAgXcx96EQvGWPJQRy7IMlPuL2s/ohcpg0R52WZSsaA+GuqlLSFg5CoMvGqD J2qIoq5YmHYw+6WiEk0Yv5H4NgrXKQuU/kbHQPOzU98Y4m8VEXeFpOrO7x4EL2HTIg4vcAHe7jo4Af 04ku8z6LNDYZQPODm8X2JvjDkM9Qh0n9XVdYQHRvZoFahFDC1yzc9Z10cPXmnXdlqqUP5sxXk9f1uN 8JCF//jEoeuAz35R259jHCriJgW1Dm1/kJ6A9CAZsvj4uYaUSaoQQf6Oc/3A== 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 19c297f9a52f..fea424681d66 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 43ea9ed5652e..8d7cdb8a6391 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; @@ -1616,8 +1623,19 @@ 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); @@ -7021,6 +7039,96 @@ 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