From patchwork Thu Jul 9 00:56:51 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: KP Singh X-Patchwork-Id: 11653143 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id C8551739 for ; Thu, 9 Jul 2020 00:57:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8FE9920772 for ; Thu, 9 Jul 2020 00:57:20 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="mxLr5p+a" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726223AbgGIA5S (ORCPT ); Wed, 8 Jul 2020 20:57:18 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34454 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726171AbgGIA5B (ORCPT ); Wed, 8 Jul 2020 20:57:01 -0400 Received: from mail-wm1-x344.google.com (mail-wm1-x344.google.com [IPv6:2a00:1450:4864:20::344]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0D9EEC08C5C1 for ; Wed, 8 Jul 2020 17:57:01 -0700 (PDT) Received: by mail-wm1-x344.google.com with SMTP id f18so167248wml.3 for ; Wed, 08 Jul 2020 17:57:00 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=u6m8e30EuuqaGC96fhEBQgdiUeSD+Q6cBdexSZmuLkE=; b=mxLr5p+awW6F1X9EiQqZwXH12RuxBcxpC9OQEZ2+VljI58lIV+MzMXmuzdJnpHOquR HAjnAbh/8TJZnyn6QXw5oQL9E9/0U66LPohl4clkk6pt2TAtPgTOd5ACwP+B9FKMs97z JSCu9rz2POp7vuECXGRRvQfM8qNGYJVB/VG8E= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=u6m8e30EuuqaGC96fhEBQgdiUeSD+Q6cBdexSZmuLkE=; b=MEnSCRGtOe1H2nzEpr33zq7MgGIOOaOBy/704AMhbla7xywbxEOQxpeIdx15HWnyCQ hrH1hDpv95d23jTwuTapmYFFdzNug4chScD391Twh12mtSyjCeZOmEYBf5vA2ws0OTGs wKNkUtcn3rHLpsA89OcgPPtc/ZZFU5OwO6/24qQvjP+sv53RPPyjWY50HrGsEV6LFqkR xlzxFwt+rPd4C+N60qWndvHYGVNUCVDS0r+Ns+/xjFmQpPxk1kZzvWpmxzlgYDpcvBrJ Z295eOfUgzr7BY/r/8TvsfoRsMPUqyYmkB7MWszCDKMJD+ee7Bf7ZHGiXekQvK/xrpOE KzMQ== X-Gm-Message-State: AOAM531ONYDtAm/2AGGgQuX5XHyUKgKLUnnEgInxRS4AaDeKCK8SwO/G ZNHbuDv5VvJLNgyJ8yzEH2mUwQ== X-Google-Smtp-Source: ABdhPJxhK6sk/snSlk83hfY01lw70BVKMMPl6VX11MrHInOZnEmDko/jD7V7EiryoXK8vwgaJUYh1g== X-Received: by 2002:a1c:7f82:: with SMTP id a124mr10913758wmd.132.1594256218751; Wed, 08 Jul 2020 17:56:58 -0700 (PDT) Received: from kpsingh.zrh.corp.google.com ([81.6.44.51]) by smtp.gmail.com with ESMTPSA id f15sm2465498wrx.91.2020.07.08.17.56.57 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 08 Jul 2020 17:56:58 -0700 (PDT) From: KP Singh To: linux-kernel@vger.kernel.org, bpf@vger.kernel.org, linux-security-module@vger.kernel.org Cc: Alexei Starovoitov , Daniel Borkmann , Paul Turner , Jann Horn , Florent Revest Subject: [PATCH bpf-next v3 1/4] bpf: Generalize bpf_sk_storage Date: Thu, 9 Jul 2020 02:56:51 +0200 Message-Id: <20200709005654.3324272-2-kpsingh@chromium.org> X-Mailer: git-send-email 2.27.0.389.gc38d7665816-goog In-Reply-To: <20200709005654.3324272-1-kpsingh@chromium.org> References: <20200709005654.3324272-1-kpsingh@chromium.org> MIME-Version: 1.0 Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: From: KP Singh Refactor the functionality in bpf_sk_storage.c so that concept of storage linked to kernel objects can be extended to other objects like inode, task_struct etc. bpf_sk_storage is updated to be bpf_local_storage with a union that contains a pointer to the owner object. The type of the bpf_local_storage can be determined using the newly added bpf_local_storage_type enum. Each new local storage will still be a separate map and provide its own set of helpers. This allows for future object specific extensions and still share a lot of the underlying implementation. Signed-off-by: KP Singh --- include/linux/bpf.h | 14 + include/linux/bpf_local_storage.h | 175 +++++++ include/net/sock.h | 4 +- include/uapi/linux/bpf.h | 12 +- kernel/bpf/Makefile | 1 + kernel/bpf/bpf_local_storage.c | 517 +++++++++++++++++++ net/core/bpf_sk_storage.c | 804 ++++++------------------------ tools/include/uapi/linux/bpf.h | 12 +- 8 files changed, 879 insertions(+), 660 deletions(-) create mode 100644 include/linux/bpf_local_storage.h create mode 100644 kernel/bpf/bpf_local_storage.c diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 0cd7f6884c5c..95ab7031cd8e 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -33,6 +33,9 @@ struct btf; struct btf_type; struct exception_table_entry; struct seq_operations; +struct bpf_local_storage; +struct bpf_local_storage_map; +struct bpf_local_storage_elem; extern struct idr btf_idr; extern spinlock_t btf_idr_lock; @@ -93,6 +96,17 @@ struct bpf_map_ops { __poll_t (*map_poll)(struct bpf_map *map, struct file *filp, struct poll_table_struct *pts); + /* Functions called by bpf_local_storage maps */ + void (*map_local_storage_unlink)(struct bpf_local_storage *local_storage, + bool uncharge_omem); + struct bpf_local_storage_elem *(*map_selem_alloc)( + struct bpf_local_storage_map *smap, void *owner, void *value, + bool charge_omem); + struct bpf_local_storage_data *(*map_local_storage_update)( + void *owner, struct bpf_map *map, void *value, u64 flags); + int (*map_local_storage_alloc)(void *owner, + struct bpf_local_storage_map *smap, + struct bpf_local_storage_elem *elem); /* BTF name and id of struct allocated by map_alloc */ const char * const map_btf_name; int *map_btf_id; diff --git a/include/linux/bpf_local_storage.h b/include/linux/bpf_local_storage.h new file mode 100644 index 000000000000..605b81f2f806 --- /dev/null +++ b/include/linux/bpf_local_storage.h @@ -0,0 +1,175 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Copyright (c) 2019 Facebook + * Copyright 2020 Google LLC. + */ + +#ifndef _BPF_LOCAL_STORAGE_H +#define _BPF_LOCAL_STORAGE_H + +#include +#include +#include +#include +#include +#include + +#define LOCAL_STORAGE_CREATE_FLAG_MASK \ + (BPF_F_NO_PREALLOC | BPF_F_CLONE) + +struct bucket { + struct hlist_head list; + raw_spinlock_t lock; +}; + +/* Thp map is not the primary owner of a bpf_local_storage_elem. + * Instead, the container object (eg. sk->sk_bpf_storage) is. + * + * The map (bpf_local_storage_map) is for two purposes + * 1. Define the size of the "local storage". It is + * the map's value_size. + * + * 2. Maintain a list to keep track of all elems such + * that they can be cleaned up during the map destruction. + * + * When a bpf local storage is being looked up for a + * particular object, the "bpf_map" pointer is actually used + * as the "key" to search in the list of elem in + * the respective bpf_local_storage owned by the object. + * + * e.g. sk->sk_bpf_storage is the mini-map with the "bpf_map" pointer + * as the searching key. + */ +struct bpf_local_storage_map { + struct bpf_map map; + /* Lookup elem does not require accessing the map. + * + * Updating/Deleting requires a bucket lock to + * link/unlink the elem from the map. Having + * multiple buckets to improve contention. + */ + struct bucket *buckets; + u32 bucket_log; + u16 elem_size; + u16 cache_idx; +}; + +struct bpf_local_storage_data { + /* smap is used as the searching key when looking up + * from the obejct's bpf_local_storage. + * + * Put it in the same cacheline as the data to minimize + * the number of cachelines access during the cache hit case. + */ + struct bpf_local_storage_map __rcu *smap; + u8 data[] __aligned(8); +}; + +/* Linked to bpf_local_storage and bpf_local_storage_map */ +struct bpf_local_storage_elem { + struct hlist_node map_node; /* Linked to bpf_local_storage_map */ + struct hlist_node snode; /* Linked to bpf_local_storage */ + struct bpf_local_storage __rcu *local_storage; + struct rcu_head rcu; + /* 8 bytes hole */ + /* The data is stored in aother cacheline to minimize + * the number of cachelines access during a cache hit. + */ + struct bpf_local_storage_data sdata ____cacheline_aligned; +}; + +#define SELEM(_SDATA) \ + container_of((_SDATA), struct bpf_local_storage_elem, sdata) +#define SDATA(_SELEM) (&(_SELEM)->sdata) +#define BPF_STORAGE_CACHE_SIZE 16 + +u16 bpf_ls_cache_idx_get(spinlock_t *cache_idx_lock, + u64 *cache_idx_usage_count); + +void bpf_ls_cache_idx_free(spinlock_t *cache_idx_lock, + u64 *cache_idx_usage_counts, u16 idx); + +#define DEFINE_BPF_STORAGE_CACHE(type) \ +static DEFINE_SPINLOCK(cache_idx_lock_##type); \ +static u64 cache_idx_usage_counts_##type[BPF_STORAGE_CACHE_SIZE]; \ +static u16 cache_idx_get_##type(void) \ +{ \ + return bpf_ls_cache_idx_get(&cache_idx_lock_##type, \ + cache_idx_usage_counts_##type); \ +} \ +static void cache_idx_free_##type(u16 idx) \ +{ \ + return bpf_ls_cache_idx_free(&cache_idx_lock_##type, \ + cache_idx_usage_counts_##type, \ + idx); \ +} + +/* U16_MAX is much more than enough for sk local storage + * considering a tcp_sock is ~2k. + */ +#define BPF_LOCAL_STORAGE_MAX_VALUE_SIZE \ + min_t(u32, \ + (KMALLOC_MAX_SIZE - MAX_BPF_STACK - \ + sizeof(struct bpf_local_storage_elem)), \ + (U16_MAX - sizeof(struct bpf_local_storage_elem))) + +struct bpf_local_storage { + struct bpf_local_storage_data __rcu *cache[BPF_STORAGE_CACHE_SIZE]; + struct hlist_head list; /* List of bpf_local_storage_elem */ + /* The object that owns the the above "list" of + * bpf_local_storage_elem + */ + union { + struct sock *sk; + }; + struct rcu_head rcu; + raw_spinlock_t lock; /* Protect adding/removing from the "list" */ +}; + +/* Helper functions for bpf_local_storage */ +int bpf_local_storage_map_alloc_check(union bpf_attr *attr); + +struct bpf_local_storage_map *bpf_local_storage_map_alloc(union bpf_attr *attr); + +struct bpf_local_storage_data * +bpf_local_storage_lookup(struct bpf_local_storage *local_storage, + struct bpf_local_storage_map *smap, + bool cacheit_lockit); + +void bpf_local_storage_map_free(struct bpf_local_storage_map *smap); + +int bpf_local_storage_map_check_btf(const struct bpf_map *map, + const struct btf *btf, + const struct btf_type *key_type, + const struct btf_type *value_type); + +void bpf_selem_link(struct bpf_local_storage *local_storage, + struct bpf_local_storage_elem *selem); + +bool bpf_selem_unlink(struct bpf_local_storage *local_storage, + struct bpf_local_storage_elem *selem, bool uncharge_omem); + +void bpf_selem_unlink_map_elem(struct bpf_local_storage_elem *selem); + +void bpf_selem_link_map(struct bpf_local_storage_map *smap, + struct bpf_local_storage_elem *selem); + +void bpf_selem_unlink_map(struct bpf_local_storage_elem *selem); + +struct bpf_local_storage_elem * +bpf_selem_alloc(struct bpf_local_storage_map *smap, void *value); + +struct bpf_local_storage * +bpf_local_storage_alloc(struct bpf_local_storage_map *smap); + +int bpf_local_storage_publish(struct bpf_local_storage_elem *first_selem, + struct bpf_local_storage **addr, + struct bpf_local_storage *curr); + +int bpf_local_storage_check_update_flags(struct bpf_map *map, u64 map_flags); + +struct bpf_local_storage_data * +bpf_local_storage_update(void *owner, struct bpf_map *map, + struct bpf_local_storage *local_storage, void *value, + u64 map_flags); +#endif /* _BPF_LOCAL_STORAGE_H */ diff --git a/include/net/sock.h b/include/net/sock.h index 84c813dd0152..5eada8a5eb21 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -245,7 +245,7 @@ struct sock_common { /* public: */ }; -struct bpf_sk_storage; +struct bpf_local_storage; /** * struct sock - network layer representation of sockets @@ -516,7 +516,7 @@ struct sock { void (*sk_destruct)(struct sock *sk); struct sock_reuseport __rcu *sk_reuseport_cb; #ifdef CONFIG_BPF_SYSCALL - struct bpf_sk_storage __rcu *sk_bpf_storage; + struct bpf_local_storage __rcu *sk_bpf_storage; #endif struct rcu_head sk_rcu; }; diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 548a749aebb3..1f3e831c4813 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -2802,10 +2802,10 @@ union bpf_attr { * "type". The bpf-local-storage "type" (i.e. the *map*) is * searched against all bpf-local-storages residing at *sk*. * - * An optional *flags* (**BPF_SK_STORAGE_GET_F_CREATE**) can be + * An optional *flags* (**BPF_LOCAL_STORAGE_GET_F_CREATE**) can be * used such that a new bpf-local-storage will be * created if one does not exist. *value* can be used - * together with **BPF_SK_STORAGE_GET_F_CREATE** to specify + * together with **BPF_LOCAL_STORAGE_GET_F_CREATE** to specify * the initial value of a bpf-local-storage. If *value* is * **NULL**, the new bpf-local-storage will be zero initialized. * Return @@ -3572,9 +3572,13 @@ enum { BPF_F_SYSCTL_BASE_NAME = (1ULL << 0), }; -/* BPF_FUNC_sk_storage_get flags */ +/* BPF_FUNC__storage_get flags */ enum { - BPF_SK_STORAGE_GET_F_CREATE = (1ULL << 0), + BPF_LOCAL_STORAGE_GET_F_CREATE = (1ULL << 0), + /* BPF_SK_STORAGE_GET_F_CREATE is only kept for backward compatibility + * and BPF_LOCAL_STORAGE_GET_F_CREATE must be used instead. + */ + BPF_SK_STORAGE_GET_F_CREATE = BPF_LOCAL_STORAGE_GET_F_CREATE, }; /* BPF_FUNC_read_branch_records flags. */ diff --git a/kernel/bpf/Makefile b/kernel/bpf/Makefile index 1131a921e1a6..0acb8f8a6042 100644 --- a/kernel/bpf/Makefile +++ b/kernel/bpf/Makefile @@ -12,6 +12,7 @@ obj-$(CONFIG_BPF_JIT) += dispatcher.o ifeq ($(CONFIG_NET),y) obj-$(CONFIG_BPF_SYSCALL) += devmap.o obj-$(CONFIG_BPF_SYSCALL) += cpumap.o +obj-$(CONFIG_BPF_SYSCALL) += bpf_local_storage.o obj-$(CONFIG_BPF_SYSCALL) += offload.o obj-$(CONFIG_BPF_SYSCALL) += net_namespace.o endif diff --git a/kernel/bpf/bpf_local_storage.c b/kernel/bpf/bpf_local_storage.c new file mode 100644 index 000000000000..c818eb6f8261 --- /dev/null +++ b/kernel/bpf/bpf_local_storage.c @@ -0,0 +1,517 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (c) 2019 Facebook + * Copyright 2020 Google LLC. + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#define SELEM(_SDATA) \ + container_of((_SDATA), struct bpf_local_storage_elem, sdata) +#define SDATA(_SELEM) (&(_SELEM)->sdata) + +static struct bucket *select_bucket(struct bpf_local_storage_map *smap, + struct bpf_local_storage_elem *selem) +{ + return &smap->buckets[hash_ptr(selem, smap->bucket_log)]; +} + +static bool selem_linked_to_node(const struct bpf_local_storage_elem *selem) +{ + return !hlist_unhashed(&selem->snode); +} + +static bool selem_linked_to_map(const struct bpf_local_storage_elem *selem) +{ + return !hlist_unhashed(&selem->map_node); +} + +struct bpf_local_storage_elem * +bpf_selem_alloc(struct bpf_local_storage_map *smap, void *value) +{ + struct bpf_local_storage_elem *selem; + + selem = kzalloc(smap->elem_size, GFP_ATOMIC | __GFP_NOWARN); + if (selem) { + if (value) + memcpy(SDATA(selem)->data, value, smap->map.value_size); + return selem; + } + + return NULL; +} + +/* local_storage->lock must be held and selem->local_storage == local_storage. + * The caller must ensure selem->smap is still valid to be + * dereferenced for its smap->elem_size and smap->cache_idx. + * + * uncharge_omem is only relevant for BPF_MAP_TYPE_SK_STORAGE. + */ +bool bpf_selem_unlink(struct bpf_local_storage *local_storage, + struct bpf_local_storage_elem *selem, bool uncharge_omem) +{ + struct bpf_local_storage_map *smap; + bool free_local_storage; + + smap = rcu_dereference(SDATA(selem)->smap); + free_local_storage = hlist_is_singular_node(&selem->snode, + &local_storage->list); + + /* local_storage is not freed now. local_storage->lock is + * still held and raw_spin_unlock_bh(&local_storage->lock) + * will be done by the caller. + * Although the unlock will be done under + * rcu_read_lock(), it is more intutivie to + * read if kfree_rcu(local_storage, rcu) is done + * after the raw_spin_unlock_bh(&local_storage->lock). + * + * Hence, a "bool free_local_storage" is returned + * to the caller which then calls the kfree_rcu() + * after unlock. + */ + if (free_local_storage) + smap->map.ops->map_local_storage_unlink(local_storage, + uncharge_omem); + + hlist_del_init_rcu(&selem->snode); + if (rcu_access_pointer(local_storage->cache[smap->cache_idx]) == + SDATA(selem)) + RCU_INIT_POINTER(local_storage->cache[smap->cache_idx], NULL); + + kfree_rcu(selem, rcu); + + return free_local_storage; +} + +void bpf_selem_link(struct bpf_local_storage *local_storage, + struct bpf_local_storage_elem *selem) +{ + RCU_INIT_POINTER(selem->local_storage, local_storage); + hlist_add_head(&selem->snode, &local_storage->list); +} + +void bpf_selem_unlink_map(struct bpf_local_storage_elem *selem) +{ + struct bpf_local_storage_map *smap; + struct bucket *b; + + if (unlikely(!selem_linked_to_map(selem))) + /* selem has already be unlinked from smap */ + return; + + smap = rcu_dereference(SDATA(selem)->smap); + b = select_bucket(smap, selem); + raw_spin_lock_bh(&b->lock); + if (likely(selem_linked_to_map(selem))) + hlist_del_init_rcu(&selem->map_node); + raw_spin_unlock_bh(&b->lock); +} + +void bpf_selem_link_map(struct bpf_local_storage_map *smap, + struct bpf_local_storage_elem *selem) +{ + struct bucket *b = select_bucket(smap, selem); + + raw_spin_lock_bh(&b->lock); + RCU_INIT_POINTER(SDATA(selem)->smap, smap); + hlist_add_head_rcu(&selem->map_node, &b->list); + raw_spin_unlock_bh(&b->lock); +} + +void bpf_selem_unlink_map_elem(struct bpf_local_storage_elem *selem) +{ + struct bpf_local_storage *local_storage; + bool free_local_storage = false; + + /* Always unlink from map before unlinking from local_storage + * because selem will be freed after successfully unlinked from + * the local_storage. + */ + bpf_selem_unlink_map(selem); + + if (unlikely(!selem_linked_to_node(selem))) + /* selem has already been unlinked from its owner */ + return; + + local_storage = rcu_dereference(selem->local_storage); + raw_spin_lock_bh(&local_storage->lock); + if (likely(selem_linked_to_node(selem))) + free_local_storage = + bpf_selem_unlink(local_storage, selem, true); + raw_spin_unlock_bh(&local_storage->lock); + + if (free_local_storage) + kfree_rcu(local_storage, rcu); +} + +struct bpf_local_storage_data * +bpf_local_storage_lookup(struct bpf_local_storage *local_storage, + struct bpf_local_storage_map *smap, + bool cacheit_lockit) +{ + struct bpf_local_storage_data *sdata; + struct bpf_local_storage_elem *selem; + + /* Fast path (cache hit) */ + sdata = rcu_dereference(local_storage->cache[smap->cache_idx]); + if (sdata && rcu_access_pointer(sdata->smap) == smap) + return sdata; + + /* Slow path (cache miss) */ + hlist_for_each_entry_rcu(selem, &local_storage->list, snode) + if (rcu_access_pointer(SDATA(selem)->smap) == smap) + break; + + if (!selem) + return NULL; + + sdata = SDATA(selem); + if (cacheit_lockit) { + /* spinlock is needed to avoid racing with the + * parallel delete. Otherwise, publishing an already + * deleted sdata to the cache will become a use-after-free + * problem in the next bpf_local_storage_lookup(). + */ + raw_spin_lock_bh(&local_storage->lock); + if (selem_linked_to_node(selem)) + rcu_assign_pointer( + local_storage->cache[smap->cache_idx], sdata); + raw_spin_unlock_bh(&local_storage->lock); + } + + return sdata; +} + +static int check_flags(const struct bpf_local_storage_data *old_sdata, + u64 map_flags) +{ + if (old_sdata && (map_flags & ~BPF_F_LOCK) == BPF_NOEXIST) + /* elem already exists */ + return -EEXIST; + + if (!old_sdata && (map_flags & ~BPF_F_LOCK) == BPF_EXIST) + /* elem doesn't exist, cannot update it */ + return -ENOENT; + + return 0; +} + +struct bpf_local_storage * +bpf_local_storage_alloc(struct bpf_local_storage_map *smap) +{ + struct bpf_local_storage *storage; + + storage = kzalloc(sizeof(*storage), GFP_ATOMIC | __GFP_NOWARN); + if (!storage) + return NULL; + + INIT_HLIST_HEAD(&storage->list); + raw_spin_lock_init(&storage->lock); + return storage; +} + +/* Publish local_storage to the address. This is used because we are already + * in a region where we cannot grab a lock on the object owning the storage ( + * (e.g sk->sk_lock). Hence, atomic ops is used. + * + * From now on, the addr pointer is protected + * by the local_storage->lock. Hence, upon freeing, + * the local_storage->lock must be held before unlinking the storage from the + * owner. + */ +int bpf_local_storage_publish(struct bpf_local_storage_elem *first_selem, + struct bpf_local_storage **addr, + struct bpf_local_storage *curr) +{ + struct bpf_local_storage *prev; + + prev = cmpxchg(addr, NULL, curr); + if (unlikely(prev)) { + /* Note that even first_selem was linked to smap's + * bucket->list, first_selem can be freed immediately + * (instead of kfree_rcu) because + * bpf_local_storage_map_free() does a + * synchronize_rcu() before walking the bucket->list. + * Hence, no one is accessing selem from the + * bucket->list under rcu_read_lock(). + */ + bpf_selem_unlink_map(first_selem); + return -EAGAIN; + } + + return 0; +} + +int bpf_local_storage_check_update_flags(struct bpf_map *map, u64 map_flags) +{ + /* BPF_EXIST and BPF_NOEXIST cannot be both set */ + if (unlikely((map_flags & ~BPF_F_LOCK) > BPF_EXIST) || + /* BPF_F_LOCK can only be used in a value with spin_lock */ + unlikely((map_flags & BPF_F_LOCK) && !map_value_has_spin_lock(map))) + return -EINVAL; + + return 0; +} + +struct bpf_local_storage_data * +bpf_local_storage_update(void *owner, struct bpf_map *map, + struct bpf_local_storage *local_storage, void *value, + u64 map_flags) +{ + struct bpf_local_storage_data *old_sdata = NULL; + struct bpf_local_storage_elem *selem; + struct bpf_local_storage_map *smap; + int err; + + smap = (struct bpf_local_storage_map *)map; + + if ((map_flags & BPF_F_LOCK) && !(map_flags & BPF_NOEXIST)) { + /* Hoping to find an old_sdata to do inline update + * such that it can avoid taking the local_storage->lock + * and changing the lists. + */ + old_sdata = bpf_local_storage_lookup(local_storage, smap, false); + err = check_flags(old_sdata, map_flags); + if (err) + return ERR_PTR(err); + + if (old_sdata && selem_linked_to_node(SELEM(old_sdata))) { + copy_map_value_locked(map, old_sdata->data, + value, false); + return old_sdata; + } + } + + raw_spin_lock_bh(&local_storage->lock); + + /* Recheck local_storage->list under local_storage->lock */ + if (unlikely(hlist_empty(&local_storage->list))) { + /* A parallel del is happening and local_storage is going + * away. It has just been checked before, so very + * unlikely. Return instead of retry to keep things + * simple. + */ + err = -EAGAIN; + goto unlock_err; + } + + old_sdata = bpf_local_storage_lookup(local_storage, smap, false); + err = check_flags(old_sdata, map_flags); + if (err) + goto unlock_err; + + if (old_sdata && (map_flags & BPF_F_LOCK)) { + copy_map_value_locked(map, old_sdata->data, value, false); + selem = SELEM(old_sdata); + goto unlock; + } + + /* local_storage->lock is held. Hence, we are sure + * we can unlink and uncharge the old_sdata successfully + * later. Hence, instead of charging the new selem now + * and then uncharge the old selem later (which may cause + * a potential but unnecessary charge failure), avoid taking + * a charge at all here (the "!old_sdata" check) and the + * old_sdata will not be uncharged later during bpf_selem_unlink(). + */ + selem = map->ops->map_selem_alloc(smap, owner, value, !old_sdata); + if (!selem) { + err = -ENOMEM; + goto unlock_err; + } + + /* First, link the new selem to the map */ + bpf_selem_link_map(smap, selem); + + /* Second, link (and publish) the new selem to local_storage */ + bpf_selem_link(local_storage, selem); + + /* Third, remove old selem, SELEM(old_sdata) */ + if (old_sdata) { + bpf_selem_unlink_map(SELEM(old_sdata)); + bpf_selem_unlink(local_storage, SELEM(old_sdata), false); + } + +unlock: + raw_spin_unlock_bh(&local_storage->lock); + return SDATA(selem); + +unlock_err: + raw_spin_unlock_bh(&local_storage->lock); + return ERR_PTR(err); +} + +u16 bpf_ls_cache_idx_get(spinlock_t *cache_idx_lock, + u64 *cache_idx_usage_counts) +{ + u64 min_usage = U64_MAX; + u16 i, res = 0; + + spin_lock(cache_idx_lock); + + for (i = 0; i < BPF_STORAGE_CACHE_SIZE; i++) { + if (cache_idx_usage_counts[i] < min_usage) { + min_usage = cache_idx_usage_counts[i]; + res = i; + + /* Found a free cache_idx */ + if (!min_usage) + break; + } + } + cache_idx_usage_counts[res]++; + + spin_unlock(cache_idx_lock); + + return res; +} + +void bpf_ls_cache_idx_free(spinlock_t *cache_idx_lock, + u64 *cache_idx_usage_counts, u16 idx) +{ + spin_lock(cache_idx_lock); + cache_idx_usage_counts[idx]--; + spin_unlock(cache_idx_lock); +} + +void bpf_local_storage_map_free(struct bpf_local_storage_map *smap) +{ + struct bpf_local_storage_elem *selem; + struct bucket *b; + unsigned int i; + + /* Note that this map might be concurrently cloned from + * bpf_sk_storage_clone. Wait for any existing bpf_sk_storage_clone + * RCU read section to finish before proceeding. New RCU + * read sections should be prevented via bpf_map_inc_not_zero. + */ + synchronize_rcu(); + + /* bpf prog and the userspace can no longer access this map + * now. No new selem (of this map) can be added + * to the bpf_local_storage or to the map bucket's list. + * + * The elem of this map can be cleaned up here + * or by bpf_local_storage_free() during the destruction of the + * owner object. eg. __sk_destruct. + */ + for (i = 0; i < (1U << smap->bucket_log); i++) { + b = &smap->buckets[i]; + + rcu_read_lock(); + /* No one is adding to b->list now */ + while ((selem = hlist_entry_safe(rcu_dereference_raw(hlist_first_rcu(&b->list)), + struct bpf_local_storage_elem, + map_node))) { + bpf_selem_unlink_map_elem(selem); + cond_resched_rcu(); + } + rcu_read_unlock(); + } + + /* bpf_local_storage_free() may still need to access the map. + * e.g. bpf_local_storage_free() has unlinked selem from the map + * which then made the above while((selem = ...)) loop + * exited immediately. + * + * However, the bpf_local_storage_free() still needs to access + * the smap->elem_size to do the uncharging in + * bpf_selem_unlink(). + * + * Hence, wait another rcu grace period for the + * bpf_local_storage_free() to finish. + */ + synchronize_rcu(); + + kvfree(smap->buckets); + kfree(smap); +} + +int bpf_local_storage_map_alloc_check(union bpf_attr *attr) +{ + if (attr->map_flags & ~LOCAL_STORAGE_CREATE_FLAG_MASK || + !(attr->map_flags & BPF_F_NO_PREALLOC) || + attr->max_entries || + attr->key_size != sizeof(int) || !attr->value_size || + /* Enforce BTF for userspace sk dumping */ + !attr->btf_key_type_id || !attr->btf_value_type_id) + return -EINVAL; + + if (!bpf_capable()) + return -EPERM; + + if (attr->value_size > BPF_LOCAL_STORAGE_MAX_VALUE_SIZE) + return -E2BIG; + + return 0; +} + +struct bpf_local_storage_map *bpf_local_storage_map_alloc(union bpf_attr *attr) +{ + struct bpf_local_storage_map *smap; + unsigned int i; + u32 nbuckets; + u64 cost; + int ret; + + smap = kzalloc(sizeof(*smap), GFP_USER | __GFP_NOWARN); + if (!smap) + return ERR_PTR(-ENOMEM); + bpf_map_init_from_attr(&smap->map, attr); + + nbuckets = roundup_pow_of_two(num_possible_cpus()); + /* Use at least 2 buckets, select_bucket() is undefined behavior with 1 bucket */ + nbuckets = max_t(u32, 2, nbuckets); + smap->bucket_log = ilog2(nbuckets); + cost = sizeof(*smap->buckets) * nbuckets + sizeof(*smap); + + ret = bpf_map_charge_init(&smap->map.memory, cost); + if (ret < 0) { + kfree(smap); + return ERR_PTR(ret); + } + + smap->buckets = kvcalloc(sizeof(*smap->buckets), nbuckets, + GFP_USER | __GFP_NOWARN); + if (!smap->buckets) { + bpf_map_charge_finish(&smap->map.memory); + kfree(smap); + return ERR_PTR(-ENOMEM); + } + + for (i = 0; i < nbuckets; i++) { + INIT_HLIST_HEAD(&smap->buckets[i].list); + raw_spin_lock_init(&smap->buckets[i].lock); + } + + smap->elem_size = + sizeof(struct bpf_local_storage_elem) + attr->value_size; + + return smap; +} + +int bpf_local_storage_map_check_btf(const struct bpf_map *map, + const struct btf *btf, + const struct btf_type *key_type, + const struct btf_type *value_type) +{ + u32 int_data; + + if (BTF_INFO_KIND(key_type->info) != BTF_KIND_INT) + return -EINVAL; + + int_data = *(u32 *)(key_type + 1); + if (BTF_INT_BITS(int_data) != 32 || BTF_INT_OFFSET(int_data)) + return -EINVAL; + + return 0; +} diff --git a/net/core/bpf_sk_storage.c b/net/core/bpf_sk_storage.c index 6f921c4ddc2c..62b6526acf7e 100644 --- a/net/core/bpf_sk_storage.c +++ b/net/core/bpf_sk_storage.c @@ -1,103 +1,19 @@ // SPDX-License-Identifier: GPL-2.0 /* Copyright (c) 2019 Facebook */ +#include "linux/bpf.h" +#include "asm-generic/bug.h" +#include "linux/err.h" #include #include #include #include #include #include -#include +#include #include #include #include -#define SK_STORAGE_CREATE_FLAG_MASK \ - (BPF_F_NO_PREALLOC | BPF_F_CLONE) - -struct bucket { - struct hlist_head list; - raw_spinlock_t lock; -}; - -/* Thp map is not the primary owner of a bpf_sk_storage_elem. - * Instead, the sk->sk_bpf_storage is. - * - * The map (bpf_sk_storage_map) is for two purposes - * 1. Define the size of the "sk local storage". It is - * the map's value_size. - * - * 2. Maintain a list to keep track of all elems such - * that they can be cleaned up during the map destruction. - * - * When a bpf local storage is being looked up for a - * particular sk, the "bpf_map" pointer is actually used - * as the "key" to search in the list of elem in - * sk->sk_bpf_storage. - * - * Hence, consider sk->sk_bpf_storage is the mini-map - * with the "bpf_map" pointer as the searching key. - */ -struct bpf_sk_storage_map { - struct bpf_map map; - /* Lookup elem does not require accessing the map. - * - * Updating/Deleting requires a bucket lock to - * link/unlink the elem from the map. Having - * multiple buckets to improve contention. - */ - struct bucket *buckets; - u32 bucket_log; - u16 elem_size; - u16 cache_idx; -}; - -struct bpf_sk_storage_data { - /* smap is used as the searching key when looking up - * from sk->sk_bpf_storage. - * - * Put it in the same cacheline as the data to minimize - * the number of cachelines access during the cache hit case. - */ - struct bpf_sk_storage_map __rcu *smap; - u8 data[] __aligned(8); -}; - -/* Linked to bpf_sk_storage and bpf_sk_storage_map */ -struct bpf_sk_storage_elem { - struct hlist_node map_node; /* Linked to bpf_sk_storage_map */ - struct hlist_node snode; /* Linked to bpf_sk_storage */ - struct bpf_sk_storage __rcu *sk_storage; - struct rcu_head rcu; - /* 8 bytes hole */ - /* The data is stored in aother cacheline to minimize - * the number of cachelines access during a cache hit. - */ - struct bpf_sk_storage_data sdata ____cacheline_aligned; -}; - -#define SELEM(_SDATA) container_of((_SDATA), struct bpf_sk_storage_elem, sdata) -#define SDATA(_SELEM) (&(_SELEM)->sdata) -#define BPF_SK_STORAGE_CACHE_SIZE 16 - -static DEFINE_SPINLOCK(cache_idx_lock); -static u64 cache_idx_usage_counts[BPF_SK_STORAGE_CACHE_SIZE]; - -struct bpf_sk_storage { - struct bpf_sk_storage_data __rcu *cache[BPF_SK_STORAGE_CACHE_SIZE]; - struct hlist_head list; /* List of bpf_sk_storage_elem */ - struct sock *sk; /* The sk that owns the the above "list" of - * bpf_sk_storage_elem. - */ - struct rcu_head rcu; - raw_spinlock_t lock; /* Protect adding/removing from the "list" */ -}; - -static struct bucket *select_bucket(struct bpf_sk_storage_map *smap, - struct bpf_sk_storage_elem *selem) -{ - return &smap->buckets[hash_ptr(selem, smap->bucket_log)]; -} - static int omem_charge(struct sock *sk, unsigned int size) { /* same check as in sock_kmalloc() */ @@ -110,31 +26,19 @@ static int omem_charge(struct sock *sk, unsigned int size) return -ENOMEM; } -static bool selem_linked_to_sk(const struct bpf_sk_storage_elem *selem) -{ - return !hlist_unhashed(&selem->snode); -} - -static bool selem_linked_to_map(const struct bpf_sk_storage_elem *selem) +static struct bpf_local_storage_elem * +sk_selem_alloc(struct bpf_local_storage_map *smap, void *owner, void *value, + bool charge_omem) { - return !hlist_unhashed(&selem->map_node); -} - -static struct bpf_sk_storage_elem *selem_alloc(struct bpf_sk_storage_map *smap, - struct sock *sk, void *value, - bool charge_omem) -{ - struct bpf_sk_storage_elem *selem; + struct bpf_local_storage_elem *selem; + struct sock *sk = owner; if (charge_omem && omem_charge(sk, smap->elem_size)) return NULL; - selem = kzalloc(smap->elem_size, GFP_ATOMIC | __GFP_NOWARN); - if (selem) { - if (value) - memcpy(SDATA(selem)->data, value, smap->map.value_size); + selem = bpf_selem_alloc(smap, value); + if (selem) return selem; - } if (charge_omem) atomic_sub(smap->elem_size, &sk->sk_omem_alloc); @@ -142,242 +46,53 @@ static struct bpf_sk_storage_elem *selem_alloc(struct bpf_sk_storage_map *smap, return NULL; } -/* sk_storage->lock must be held and selem->sk_storage == sk_storage. - * The caller must ensure selem->smap is still valid to be - * dereferenced for its smap->elem_size and smap->cache_idx. - */ -static bool __selem_unlink_sk(struct bpf_sk_storage *sk_storage, - struct bpf_sk_storage_elem *selem, +static void unlink_sk_storage(struct bpf_local_storage *local_storage, bool uncharge_omem) { - struct bpf_sk_storage_map *smap; - bool free_sk_storage; - struct sock *sk; - - smap = rcu_dereference(SDATA(selem)->smap); - sk = sk_storage->sk; + struct sock *sk = local_storage->sk; - /* All uncharging on sk->sk_omem_alloc must be done first. - * sk may be freed once the last selem is unlinked from sk_storage. - */ if (uncharge_omem) - atomic_sub(smap->elem_size, &sk->sk_omem_alloc); - - free_sk_storage = hlist_is_singular_node(&selem->snode, - &sk_storage->list); - if (free_sk_storage) { - atomic_sub(sizeof(struct bpf_sk_storage), &sk->sk_omem_alloc); - sk_storage->sk = NULL; - /* After this RCU_INIT, sk may be freed and cannot be used */ - RCU_INIT_POINTER(sk->sk_bpf_storage, NULL); - - /* sk_storage is not freed now. sk_storage->lock is - * still held and raw_spin_unlock_bh(&sk_storage->lock) - * will be done by the caller. - * - * Although the unlock will be done under - * rcu_read_lock(), it is more intutivie to - * read if kfree_rcu(sk_storage, rcu) is done - * after the raw_spin_unlock_bh(&sk_storage->lock). - * - * Hence, a "bool free_sk_storage" is returned - * to the caller which then calls the kfree_rcu() - * after unlock. - */ - } - hlist_del_init_rcu(&selem->snode); - if (rcu_access_pointer(sk_storage->cache[smap->cache_idx]) == - SDATA(selem)) - RCU_INIT_POINTER(sk_storage->cache[smap->cache_idx], NULL); - - kfree_rcu(selem, rcu); - - return free_sk_storage; -} - -static void selem_unlink_sk(struct bpf_sk_storage_elem *selem) -{ - struct bpf_sk_storage *sk_storage; - bool free_sk_storage = false; - - if (unlikely(!selem_linked_to_sk(selem))) - /* selem has already been unlinked from sk */ - return; - - sk_storage = rcu_dereference(selem->sk_storage); - raw_spin_lock_bh(&sk_storage->lock); - if (likely(selem_linked_to_sk(selem))) - free_sk_storage = __selem_unlink_sk(sk_storage, selem, true); - raw_spin_unlock_bh(&sk_storage->lock); - - if (free_sk_storage) - kfree_rcu(sk_storage, rcu); -} + atomic_sub(sizeof(struct bpf_local_storage), + &sk->sk_omem_alloc); -static void __selem_link_sk(struct bpf_sk_storage *sk_storage, - struct bpf_sk_storage_elem *selem) -{ - RCU_INIT_POINTER(selem->sk_storage, sk_storage); - hlist_add_head(&selem->snode, &sk_storage->list); + /* After this RCU_INIT, sk may be freed and cannot be used */ + RCU_INIT_POINTER(sk->sk_bpf_storage, NULL); + local_storage->sk = NULL; } -static void selem_unlink_map(struct bpf_sk_storage_elem *selem) +static int sk_storage_alloc(void *owner, + struct bpf_local_storage_map *smap, + struct bpf_local_storage_elem *first_selem) { - struct bpf_sk_storage_map *smap; - struct bucket *b; - - if (unlikely(!selem_linked_to_map(selem))) - /* selem has already be unlinked from smap */ - return; - - smap = rcu_dereference(SDATA(selem)->smap); - b = select_bucket(smap, selem); - raw_spin_lock_bh(&b->lock); - if (likely(selem_linked_to_map(selem))) - hlist_del_init_rcu(&selem->map_node); - raw_spin_unlock_bh(&b->lock); -} - -static void selem_link_map(struct bpf_sk_storage_map *smap, - struct bpf_sk_storage_elem *selem) -{ - struct bucket *b = select_bucket(smap, selem); - - raw_spin_lock_bh(&b->lock); - RCU_INIT_POINTER(SDATA(selem)->smap, smap); - hlist_add_head_rcu(&selem->map_node, &b->list); - raw_spin_unlock_bh(&b->lock); -} - -static void selem_unlink(struct bpf_sk_storage_elem *selem) -{ - /* Always unlink from map before unlinking from sk_storage - * because selem will be freed after successfully unlinked from - * the sk_storage. - */ - selem_unlink_map(selem); - selem_unlink_sk(selem); -} - -static struct bpf_sk_storage_data * -__sk_storage_lookup(struct bpf_sk_storage *sk_storage, - struct bpf_sk_storage_map *smap, - bool cacheit_lockit) -{ - struct bpf_sk_storage_data *sdata; - struct bpf_sk_storage_elem *selem; - - /* Fast path (cache hit) */ - sdata = rcu_dereference(sk_storage->cache[smap->cache_idx]); - if (sdata && rcu_access_pointer(sdata->smap) == smap) - return sdata; - - /* Slow path (cache miss) */ - hlist_for_each_entry_rcu(selem, &sk_storage->list, snode) - if (rcu_access_pointer(SDATA(selem)->smap) == smap) - break; - - if (!selem) - return NULL; - - sdata = SDATA(selem); - if (cacheit_lockit) { - /* spinlock is needed to avoid racing with the - * parallel delete. Otherwise, publishing an already - * deleted sdata to the cache will become a use-after-free - * problem in the next __sk_storage_lookup(). - */ - raw_spin_lock_bh(&sk_storage->lock); - if (selem_linked_to_sk(selem)) - rcu_assign_pointer(sk_storage->cache[smap->cache_idx], - sdata); - raw_spin_unlock_bh(&sk_storage->lock); - } - - return sdata; -} - -static struct bpf_sk_storage_data * -sk_storage_lookup(struct sock *sk, struct bpf_map *map, bool cacheit_lockit) -{ - struct bpf_sk_storage *sk_storage; - struct bpf_sk_storage_map *smap; - - sk_storage = rcu_dereference(sk->sk_bpf_storage); - if (!sk_storage) - return NULL; - - smap = (struct bpf_sk_storage_map *)map; - return __sk_storage_lookup(sk_storage, smap, cacheit_lockit); -} - -static int check_flags(const struct bpf_sk_storage_data *old_sdata, - u64 map_flags) -{ - if (old_sdata && (map_flags & ~BPF_F_LOCK) == BPF_NOEXIST) - /* elem already exists */ - return -EEXIST; - - if (!old_sdata && (map_flags & ~BPF_F_LOCK) == BPF_EXIST) - /* elem doesn't exist, cannot update it */ - return -ENOENT; - - return 0; -} - -static int sk_storage_alloc(struct sock *sk, - struct bpf_sk_storage_map *smap, - struct bpf_sk_storage_elem *first_selem) -{ - struct bpf_sk_storage *prev_sk_storage, *sk_storage; + struct bpf_local_storage *curr; + struct sock *sk = owner; int err; - err = omem_charge(sk, sizeof(*sk_storage)); + err = omem_charge(sk, sizeof(*curr)); if (err) return err; - sk_storage = kzalloc(sizeof(*sk_storage), GFP_ATOMIC | __GFP_NOWARN); - if (!sk_storage) { + curr = bpf_local_storage_alloc(smap); + if (!curr) { err = -ENOMEM; goto uncharge; } - INIT_HLIST_HEAD(&sk_storage->list); - raw_spin_lock_init(&sk_storage->lock); - sk_storage->sk = sk; - - __selem_link_sk(sk_storage, first_selem); - selem_link_map(smap, first_selem); - /* Publish sk_storage to sk. sk->sk_lock cannot be acquired. - * Hence, atomic ops is used to set sk->sk_bpf_storage - * from NULL to the newly allocated sk_storage ptr. - * - * From now on, the sk->sk_bpf_storage pointer is protected - * by the sk_storage->lock. Hence, when freeing - * the sk->sk_bpf_storage, the sk_storage->lock must - * be held before setting sk->sk_bpf_storage to NULL. - */ - prev_sk_storage = cmpxchg((struct bpf_sk_storage **)&sk->sk_bpf_storage, - NULL, sk_storage); - if (unlikely(prev_sk_storage)) { - selem_unlink_map(first_selem); - err = -EAGAIN; - goto uncharge; - /* Note that even first_selem was linked to smap's - * bucket->list, first_selem can be freed immediately - * (instead of kfree_rcu) because - * bpf_sk_storage_map_free() does a - * synchronize_rcu() before walking the bucket->list. - * Hence, no one is accessing selem from the - * bucket->list under rcu_read_lock(). - */ - } + curr->sk = sk; + + bpf_selem_link(curr, first_selem); + bpf_selem_link_map(smap, first_selem); + + err = bpf_local_storage_publish(first_selem, + (struct bpf_local_storage **)&sk->sk_bpf_storage, curr); + if (err) + goto uncharge; return 0; uncharge: - kfree(sk_storage); - atomic_sub(sizeof(*sk_storage), &sk->sk_omem_alloc); + kfree(curr); + atomic_sub(sizeof(*curr), &sk->sk_omem_alloc); return err; } @@ -386,36 +101,31 @@ static int sk_storage_alloc(struct sock *sk, * Otherwise, it will become a leak (and other memory issues * during map destruction). */ -static struct bpf_sk_storage_data *sk_storage_update(struct sock *sk, - struct bpf_map *map, - void *value, - u64 map_flags) +static struct bpf_local_storage_data * +sk_storage_update(void *owner, struct bpf_map *map, void *value, u64 map_flags) { - struct bpf_sk_storage_data *old_sdata = NULL; - struct bpf_sk_storage_elem *selem; - struct bpf_sk_storage *sk_storage; - struct bpf_sk_storage_map *smap; + struct bpf_local_storage_data *old_sdata = NULL; + struct bpf_local_storage_elem *selem; + struct bpf_local_storage *local_storage; + struct bpf_local_storage_map *smap; + struct sock *sk; int err; - /* BPF_EXIST and BPF_NOEXIST cannot be both set */ - if (unlikely((map_flags & ~BPF_F_LOCK) > BPF_EXIST) || - /* BPF_F_LOCK can only be used in a value with spin_lock */ - unlikely((map_flags & BPF_F_LOCK) && !map_value_has_spin_lock(map))) - return ERR_PTR(-EINVAL); + err = bpf_local_storage_check_update_flags(map, map_flags); + if (err) + return ERR_PTR(err); - smap = (struct bpf_sk_storage_map *)map; - sk_storage = rcu_dereference(sk->sk_bpf_storage); - if (!sk_storage || hlist_empty(&sk_storage->list)) { - /* Very first elem for this sk */ - err = check_flags(NULL, map_flags); - if (err) - return ERR_PTR(err); + sk = owner; + local_storage = rcu_dereference(sk->sk_bpf_storage); + smap = (struct bpf_local_storage_map *)map; - selem = selem_alloc(smap, sk, value, true); + if (!local_storage || hlist_empty(&local_storage->list)) { + /* Very first elem */ + selem = map->ops->map_selem_alloc(smap, owner, value, !old_sdata); if (!selem) return ERR_PTR(-ENOMEM); - err = sk_storage_alloc(sk, smap, selem); + err = map->ops->map_local_storage_alloc(owner, smap, selem); if (err) { kfree(selem); atomic_sub(smap->elem_size, &sk->sk_omem_alloc); @@ -425,130 +135,42 @@ static struct bpf_sk_storage_data *sk_storage_update(struct sock *sk, return SDATA(selem); } - if ((map_flags & BPF_F_LOCK) && !(map_flags & BPF_NOEXIST)) { - /* Hoping to find an old_sdata to do inline update - * such that it can avoid taking the sk_storage->lock - * and changing the lists. - */ - old_sdata = __sk_storage_lookup(sk_storage, smap, false); - err = check_flags(old_sdata, map_flags); - if (err) - return ERR_PTR(err); - if (old_sdata && selem_linked_to_sk(SELEM(old_sdata))) { - copy_map_value_locked(map, old_sdata->data, - value, false); - return old_sdata; - } - } - - raw_spin_lock_bh(&sk_storage->lock); - - /* Recheck sk_storage->list under sk_storage->lock */ - if (unlikely(hlist_empty(&sk_storage->list))) { - /* A parallel del is happening and sk_storage is going - * away. It has just been checked before, so very - * unlikely. Return instead of retry to keep things - * simple. - */ - err = -EAGAIN; - goto unlock_err; - } - - old_sdata = __sk_storage_lookup(sk_storage, smap, false); - err = check_flags(old_sdata, map_flags); - if (err) - goto unlock_err; - - if (old_sdata && (map_flags & BPF_F_LOCK)) { - copy_map_value_locked(map, old_sdata->data, value, false); - selem = SELEM(old_sdata); - goto unlock; - } - - /* sk_storage->lock is held. Hence, we are sure - * we can unlink and uncharge the old_sdata successfully - * later. Hence, instead of charging the new selem now - * and then uncharge the old selem later (which may cause - * a potential but unnecessary charge failure), avoid taking - * a charge at all here (the "!old_sdata" check) and the - * old_sdata will not be uncharged later during __selem_unlink_sk(). - */ - selem = selem_alloc(smap, sk, value, !old_sdata); - if (!selem) { - err = -ENOMEM; - goto unlock_err; - } - - /* First, link the new selem to the map */ - selem_link_map(smap, selem); - - /* Second, link (and publish) the new selem to sk_storage */ - __selem_link_sk(sk_storage, selem); + return bpf_local_storage_update(owner, map, local_storage, value, + map_flags); +} - /* Third, remove old selem, SELEM(old_sdata) */ - if (old_sdata) { - selem_unlink_map(SELEM(old_sdata)); - __selem_unlink_sk(sk_storage, SELEM(old_sdata), false); - } +static struct bpf_local_storage_data * +sk_storage_lookup(struct sock *sk, struct bpf_map *map, bool cacheit_lockit) +{ + struct bpf_local_storage *sk_storage; + struct bpf_local_storage_map *smap; -unlock: - raw_spin_unlock_bh(&sk_storage->lock); - return SDATA(selem); + sk_storage = rcu_dereference(sk->sk_bpf_storage); + if (!sk_storage) + return NULL; -unlock_err: - raw_spin_unlock_bh(&sk_storage->lock); - return ERR_PTR(err); + smap = (struct bpf_local_storage_map *)map; + return bpf_local_storage_lookup(sk_storage, smap, cacheit_lockit); } static int sk_storage_delete(struct sock *sk, struct bpf_map *map) { - struct bpf_sk_storage_data *sdata; + struct bpf_local_storage_data *sdata; sdata = sk_storage_lookup(sk, map, false); if (!sdata) return -ENOENT; - selem_unlink(SELEM(sdata)); + bpf_selem_unlink_map_elem(SELEM(sdata)); return 0; } -static u16 cache_idx_get(void) -{ - u64 min_usage = U64_MAX; - u16 i, res = 0; - - spin_lock(&cache_idx_lock); - - for (i = 0; i < BPF_SK_STORAGE_CACHE_SIZE; i++) { - if (cache_idx_usage_counts[i] < min_usage) { - min_usage = cache_idx_usage_counts[i]; - res = i; - - /* Found a free cache_idx */ - if (!min_usage) - break; - } - } - cache_idx_usage_counts[res]++; - - spin_unlock(&cache_idx_lock); - - return res; -} - -static void cache_idx_free(u16 idx) -{ - spin_lock(&cache_idx_lock); - cache_idx_usage_counts[idx]--; - spin_unlock(&cache_idx_lock); -} - /* Called by __sk_destruct() & bpf_sk_storage_clone() */ void bpf_sk_storage_free(struct sock *sk) { - struct bpf_sk_storage_elem *selem; - struct bpf_sk_storage *sk_storage; + struct bpf_local_storage_elem *selem; + struct bpf_local_storage *sk_storage; bool free_sk_storage = false; struct hlist_node *n; @@ -562,9 +184,9 @@ void bpf_sk_storage_free(struct sock *sk) /* Netiher the bpf_prog nor the bpf-map's syscall * could be modifying the sk_storage->list now. * Thus, no elem can be added-to or deleted-from the - * sk_storage->list by the bpf_prog or by the bpf-map's syscall. + * local_storage->list by the bpf_prog or by the bpf-map's syscall. * - * It is racing with bpf_sk_storage_map_free() alone + * It is racing with bpf_local_storage_map_free() alone * when unlinking elem from the sk_storage->list and * the map's bucket->list. */ @@ -573,8 +195,8 @@ void bpf_sk_storage_free(struct sock *sk) /* Always unlink from map before unlinking from * sk_storage. */ - selem_unlink_map(selem); - free_sk_storage = __selem_unlink_sk(sk_storage, selem, true); + bpf_selem_unlink_map(selem); + free_sk_storage = bpf_selem_unlink(sk_storage, selem, true); } raw_spin_unlock_bh(&sk_storage->lock); rcu_read_unlock(); @@ -583,163 +205,11 @@ void bpf_sk_storage_free(struct sock *sk) kfree_rcu(sk_storage, rcu); } -static void bpf_sk_storage_map_free(struct bpf_map *map) +static void *bpf_sk_storage_lookup_elem(struct bpf_map *map, void *key) { - struct bpf_sk_storage_elem *selem; - struct bpf_sk_storage_map *smap; - struct bucket *b; - unsigned int i; - - smap = (struct bpf_sk_storage_map *)map; - - cache_idx_free(smap->cache_idx); - - /* Note that this map might be concurrently cloned from - * bpf_sk_storage_clone. Wait for any existing bpf_sk_storage_clone - * RCU read section to finish before proceeding. New RCU - * read sections should be prevented via bpf_map_inc_not_zero. - */ - synchronize_rcu(); - - /* bpf prog and the userspace can no longer access this map - * now. No new selem (of this map) can be added - * to the sk->sk_bpf_storage or to the map bucket's list. - * - * The elem of this map can be cleaned up here - * or - * by bpf_sk_storage_free() during __sk_destruct(). - */ - for (i = 0; i < (1U << smap->bucket_log); i++) { - b = &smap->buckets[i]; - - rcu_read_lock(); - /* No one is adding to b->list now */ - while ((selem = hlist_entry_safe(rcu_dereference_raw(hlist_first_rcu(&b->list)), - struct bpf_sk_storage_elem, - map_node))) { - selem_unlink(selem); - cond_resched_rcu(); - } - rcu_read_unlock(); - } - - /* bpf_sk_storage_free() may still need to access the map. - * e.g. bpf_sk_storage_free() has unlinked selem from the map - * which then made the above while((selem = ...)) loop - * exited immediately. - * - * However, the bpf_sk_storage_free() still needs to access - * the smap->elem_size to do the uncharging in - * __selem_unlink_sk(). - * - * Hence, wait another rcu grace period for the - * bpf_sk_storage_free() to finish. - */ - synchronize_rcu(); - - kvfree(smap->buckets); - kfree(map); -} - -/* U16_MAX is much more than enough for sk local storage - * considering a tcp_sock is ~2k. - */ -#define MAX_VALUE_SIZE \ - min_t(u32, \ - (KMALLOC_MAX_SIZE - MAX_BPF_STACK - sizeof(struct bpf_sk_storage_elem)), \ - (U16_MAX - sizeof(struct bpf_sk_storage_elem))) - -static int bpf_sk_storage_map_alloc_check(union bpf_attr *attr) -{ - if (attr->map_flags & ~SK_STORAGE_CREATE_FLAG_MASK || - !(attr->map_flags & BPF_F_NO_PREALLOC) || - attr->max_entries || - attr->key_size != sizeof(int) || !attr->value_size || - /* Enforce BTF for userspace sk dumping */ - !attr->btf_key_type_id || !attr->btf_value_type_id) - return -EINVAL; - - if (!bpf_capable()) - return -EPERM; - - if (attr->value_size > MAX_VALUE_SIZE) - return -E2BIG; - - return 0; -} - -static struct bpf_map *bpf_sk_storage_map_alloc(union bpf_attr *attr) -{ - struct bpf_sk_storage_map *smap; - unsigned int i; - u32 nbuckets; - u64 cost; - int ret; - - smap = kzalloc(sizeof(*smap), GFP_USER | __GFP_NOWARN); - if (!smap) - return ERR_PTR(-ENOMEM); - bpf_map_init_from_attr(&smap->map, attr); - - nbuckets = roundup_pow_of_two(num_possible_cpus()); - /* Use at least 2 buckets, select_bucket() is undefined behavior with 1 bucket */ - nbuckets = max_t(u32, 2, nbuckets); - smap->bucket_log = ilog2(nbuckets); - cost = sizeof(*smap->buckets) * nbuckets + sizeof(*smap); - - ret = bpf_map_charge_init(&smap->map.memory, cost); - if (ret < 0) { - kfree(smap); - return ERR_PTR(ret); - } - - smap->buckets = kvcalloc(sizeof(*smap->buckets), nbuckets, - GFP_USER | __GFP_NOWARN); - if (!smap->buckets) { - bpf_map_charge_finish(&smap->map.memory); - kfree(smap); - return ERR_PTR(-ENOMEM); - } - - for (i = 0; i < nbuckets; i++) { - INIT_HLIST_HEAD(&smap->buckets[i].list); - raw_spin_lock_init(&smap->buckets[i].lock); - } - - smap->elem_size = sizeof(struct bpf_sk_storage_elem) + attr->value_size; - smap->cache_idx = cache_idx_get(); - - return &smap->map; -} - -static int notsupp_get_next_key(struct bpf_map *map, void *key, - void *next_key) -{ - return -ENOTSUPP; -} - -static int bpf_sk_storage_map_check_btf(const struct bpf_map *map, - const struct btf *btf, - const struct btf_type *key_type, - const struct btf_type *value_type) -{ - u32 int_data; - - if (BTF_INFO_KIND(key_type->info) != BTF_KIND_INT) - return -EINVAL; - - int_data = *(u32 *)(key_type + 1); - if (BTF_INT_BITS(int_data) != 32 || BTF_INT_OFFSET(int_data)) - return -EINVAL; - - return 0; -} - -static void *bpf_fd_sk_storage_lookup_elem(struct bpf_map *map, void *key) -{ - struct bpf_sk_storage_data *sdata; + struct bpf_local_storage_data *sdata; struct socket *sock; - int fd, err; + int fd, err = -EINVAL; fd = *(int *)key; sock = sockfd_lookup(fd, &err); @@ -752,17 +222,18 @@ static void *bpf_fd_sk_storage_lookup_elem(struct bpf_map *map, void *key) return ERR_PTR(err); } -static int bpf_fd_sk_storage_update_elem(struct bpf_map *map, void *key, - void *value, u64 map_flags) +static int bpf_sk_storage_update_elem(struct bpf_map *map, void *key, + void *value, u64 map_flags) { - struct bpf_sk_storage_data *sdata; + struct bpf_local_storage_data *sdata; struct socket *sock; int fd, err; fd = *(int *)key; sock = sockfd_lookup(fd, &err); if (sock) { - sdata = sk_storage_update(sock->sk, map, value, map_flags); + sdata = map->ops->map_local_storage_update(sock->sk, map, value, + map_flags); sockfd_put(sock); return PTR_ERR_OR_ZERO(sdata); } @@ -770,7 +241,7 @@ static int bpf_fd_sk_storage_update_elem(struct bpf_map *map, void *key, return err; } -static int bpf_fd_sk_storage_delete_elem(struct bpf_map *map, void *key) +static int bpf_sk_storage_delete_elem(struct bpf_map *map, void *key) { struct socket *sock; int fd, err; @@ -780,20 +251,19 @@ static int bpf_fd_sk_storage_delete_elem(struct bpf_map *map, void *key) if (sock) { err = sk_storage_delete(sock->sk, map); sockfd_put(sock); - return err; } return err; } -static struct bpf_sk_storage_elem * +static struct bpf_local_storage_elem * bpf_sk_storage_clone_elem(struct sock *newsk, - struct bpf_sk_storage_map *smap, - struct bpf_sk_storage_elem *selem) + struct bpf_local_storage_map *smap, + struct bpf_local_storage_elem *selem) { - struct bpf_sk_storage_elem *copy_selem; + struct bpf_local_storage_elem *copy_selem; - copy_selem = selem_alloc(smap, newsk, NULL, true); + copy_selem = sk_selem_alloc(smap, newsk, NULL, true); if (!copy_selem) return NULL; @@ -809,9 +279,9 @@ bpf_sk_storage_clone_elem(struct sock *newsk, int bpf_sk_storage_clone(const struct sock *sk, struct sock *newsk) { - struct bpf_sk_storage *new_sk_storage = NULL; - struct bpf_sk_storage *sk_storage; - struct bpf_sk_storage_elem *selem; + struct bpf_local_storage *new_sk_storage = NULL; + struct bpf_local_storage *sk_storage; + struct bpf_local_storage_elem *selem; int ret = 0; RCU_INIT_POINTER(newsk->sk_bpf_storage, NULL); @@ -823,8 +293,8 @@ int bpf_sk_storage_clone(const struct sock *sk, struct sock *newsk) goto out; hlist_for_each_entry_rcu(selem, &sk_storage->list, snode) { - struct bpf_sk_storage_elem *copy_selem; - struct bpf_sk_storage_map *smap; + struct bpf_local_storage_elem *copy_selem; + struct bpf_local_storage_map *smap; struct bpf_map *map; smap = rcu_dereference(SDATA(selem)->smap); @@ -832,7 +302,7 @@ int bpf_sk_storage_clone(const struct sock *sk, struct sock *newsk) continue; /* Note that for lockless listeners adding new element - * here can race with cleanup in bpf_sk_storage_map_free. + * here can race with cleanup in bpf_local_storage_map_free. * Try to grab map refcnt to make sure that it's still * alive and prevent concurrent removal. */ @@ -848,8 +318,8 @@ int bpf_sk_storage_clone(const struct sock *sk, struct sock *newsk) } if (new_sk_storage) { - selem_link_map(smap, copy_selem); - __selem_link_sk(new_sk_storage, copy_selem); + bpf_selem_link_map(smap, copy_selem); + bpf_selem_link(new_sk_storage, copy_selem); } else { ret = sk_storage_alloc(newsk, smap, copy_selem); if (ret) { @@ -860,7 +330,8 @@ int bpf_sk_storage_clone(const struct sock *sk, struct sock *newsk) goto out; } - new_sk_storage = rcu_dereference(copy_selem->sk_storage); + new_sk_storage = + rcu_dereference(copy_selem->local_storage); } bpf_map_put(map); } @@ -869,7 +340,7 @@ int bpf_sk_storage_clone(const struct sock *sk, struct sock *newsk) rcu_read_unlock(); /* In case of an error, don't free anything explicitly here, the - * caller is responsible to call bpf_sk_storage_free. + * caller is responsible to call bpf_local_storage_free. */ return ret; @@ -878,7 +349,7 @@ int bpf_sk_storage_clone(const struct sock *sk, struct sock *newsk) BPF_CALL_4(bpf_sk_storage_get, struct bpf_map *, map, struct sock *, sk, void *, value, u64, flags) { - struct bpf_sk_storage_data *sdata; + struct bpf_local_storage_data *sdata; if (flags > BPF_SK_STORAGE_GET_F_CREATE) return (unsigned long)NULL; @@ -887,7 +358,7 @@ BPF_CALL_4(bpf_sk_storage_get, struct bpf_map *, map, struct sock *, sk, if (sdata) return (unsigned long)sdata->data; - if (flags == BPF_SK_STORAGE_GET_F_CREATE && + if (flags == BPF_LOCAL_STORAGE_GET_F_CREATE && /* Cannot add new elem to a going away sk. * Otherwise, the new elem may become a leak * (and also other memory issues during map @@ -919,18 +390,51 @@ BPF_CALL_2(bpf_sk_storage_delete, struct bpf_map *, map, struct sock *, sk) return -ENOENT; } +static int notsupp_get_next_key(struct bpf_map *map, void *key, + void *next_key) +{ + return -ENOTSUPP; +} + +DEFINE_BPF_STORAGE_CACHE(sk); + +struct bpf_map *sk_storage_map_alloc(union bpf_attr *attr) +{ + struct bpf_local_storage_map *smap; + + smap = bpf_local_storage_map_alloc(attr); + if (IS_ERR(smap)) + return ERR_CAST(smap); + + smap->cache_idx = cache_idx_get_sk(); + return &smap->map; +} + +void sk_storage_map_free(struct bpf_map *map) +{ + struct bpf_local_storage_map *smap; + + smap = (struct bpf_local_storage_map *)map; + cache_idx_free_sk(smap->cache_idx); + bpf_local_storage_map_free(smap); +} + static int sk_storage_map_btf_id; const struct bpf_map_ops sk_storage_map_ops = { - .map_alloc_check = bpf_sk_storage_map_alloc_check, - .map_alloc = bpf_sk_storage_map_alloc, - .map_free = bpf_sk_storage_map_free, + .map_alloc_check = bpf_local_storage_map_alloc_check, + .map_alloc = sk_storage_map_alloc, + .map_free = sk_storage_map_free, .map_get_next_key = notsupp_get_next_key, - .map_lookup_elem = bpf_fd_sk_storage_lookup_elem, - .map_update_elem = bpf_fd_sk_storage_update_elem, - .map_delete_elem = bpf_fd_sk_storage_delete_elem, - .map_check_btf = bpf_sk_storage_map_check_btf, - .map_btf_name = "bpf_sk_storage_map", + .map_lookup_elem = bpf_sk_storage_lookup_elem, + .map_update_elem = bpf_sk_storage_update_elem, + .map_delete_elem = bpf_sk_storage_delete_elem, + .map_check_btf = bpf_local_storage_map_check_btf, + .map_btf_name = "bpf_local_storage_map", .map_btf_id = &sk_storage_map_btf_id, + .map_local_storage_alloc = sk_storage_alloc, + .map_selem_alloc = sk_selem_alloc, + .map_local_storage_update = sk_storage_update, + .map_local_storage_unlink = unlink_sk_storage, }; const struct bpf_func_proto bpf_sk_storage_get_proto = { @@ -1011,7 +515,7 @@ bpf_sk_storage_diag_alloc(const struct nlattr *nla_stgs) u32 nr_maps = 0; int rem, err; - /* bpf_sk_storage_map is currently limited to CAP_SYS_ADMIN as + /* bpf_local_storage_map is currently limited to CAP_SYS_ADMIN as * the map_alloc_check() side also does. */ if (!bpf_capable()) @@ -1061,13 +565,13 @@ bpf_sk_storage_diag_alloc(const struct nlattr *nla_stgs) } EXPORT_SYMBOL_GPL(bpf_sk_storage_diag_alloc); -static int diag_get(struct bpf_sk_storage_data *sdata, struct sk_buff *skb) +static int diag_get(struct bpf_local_storage_data *sdata, struct sk_buff *skb) { struct nlattr *nla_stg, *nla_value; - struct bpf_sk_storage_map *smap; + struct bpf_local_storage_map *smap; /* It cannot exceed max nlattr's payload */ - BUILD_BUG_ON(U16_MAX - NLA_HDRLEN < MAX_VALUE_SIZE); + BUILD_BUG_ON(U16_MAX - NLA_HDRLEN < BPF_LOCAL_STORAGE_MAX_VALUE_SIZE); nla_stg = nla_nest_start(skb, SK_DIAG_BPF_STORAGE); if (!nla_stg) @@ -1103,9 +607,9 @@ static int bpf_sk_storage_diag_put_all(struct sock *sk, struct sk_buff *skb, { /* stg_array_type (e.g. INET_DIAG_BPF_SK_STORAGES) */ unsigned int diag_size = nla_total_size(0); - struct bpf_sk_storage *sk_storage; - struct bpf_sk_storage_elem *selem; - struct bpf_sk_storage_map *smap; + struct bpf_local_storage *sk_storage; + struct bpf_local_storage_elem *selem; + struct bpf_local_storage_map *smap; struct nlattr *nla_stgs; unsigned int saved_len; int err = 0; @@ -1158,8 +662,8 @@ int bpf_sk_storage_diag_put(struct bpf_sk_storage_diag *diag, { /* stg_array_type (e.g. INET_DIAG_BPF_SK_STORAGES) */ unsigned int diag_size = nla_total_size(0); - struct bpf_sk_storage *sk_storage; - struct bpf_sk_storage_data *sdata; + struct bpf_local_storage *sk_storage; + struct bpf_local_storage_data *sdata; struct nlattr *nla_stgs; unsigned int saved_len; int err = 0; @@ -1186,8 +690,8 @@ int bpf_sk_storage_diag_put(struct bpf_sk_storage_diag *diag, saved_len = skb->len; for (i = 0; i < diag->nr_maps; i++) { - sdata = __sk_storage_lookup(sk_storage, - (struct bpf_sk_storage_map *)diag->maps[i], + sdata = bpf_local_storage_lookup(sk_storage, + (struct bpf_local_storage_map *)diag->maps[i], false); if (!sdata) diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index 548a749aebb3..1f3e831c4813 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -2802,10 +2802,10 @@ union bpf_attr { * "type". The bpf-local-storage "type" (i.e. the *map*) is * searched against all bpf-local-storages residing at *sk*. * - * An optional *flags* (**BPF_SK_STORAGE_GET_F_CREATE**) can be + * An optional *flags* (**BPF_LOCAL_STORAGE_GET_F_CREATE**) can be * used such that a new bpf-local-storage will be * created if one does not exist. *value* can be used - * together with **BPF_SK_STORAGE_GET_F_CREATE** to specify + * together with **BPF_LOCAL_STORAGE_GET_F_CREATE** to specify * the initial value of a bpf-local-storage. If *value* is * **NULL**, the new bpf-local-storage will be zero initialized. * Return @@ -3572,9 +3572,13 @@ enum { BPF_F_SYSCTL_BASE_NAME = (1ULL << 0), }; -/* BPF_FUNC_sk_storage_get flags */ +/* BPF_FUNC__storage_get flags */ enum { - BPF_SK_STORAGE_GET_F_CREATE = (1ULL << 0), + BPF_LOCAL_STORAGE_GET_F_CREATE = (1ULL << 0), + /* BPF_SK_STORAGE_GET_F_CREATE is only kept for backward compatibility + * and BPF_LOCAL_STORAGE_GET_F_CREATE must be used instead. + */ + BPF_SK_STORAGE_GET_F_CREATE = BPF_LOCAL_STORAGE_GET_F_CREATE, }; /* BPF_FUNC_read_branch_records flags. */