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 X-Spam-Level: X-Spam-Status: No, score=-16.4 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT, USER_IN_DEF_DKIM_WL autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9B756C43613 for ; Fri, 21 Jun 2019 23:17:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 69FCE20675 for ; Fri, 21 Jun 2019 23:17:36 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="qcHkxnxf" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726192AbfFUXRG (ORCPT ); Fri, 21 Jun 2019 19:17:06 -0400 Received: from mail-pf1-f202.google.com ([209.85.210.202]:43233 "EHLO mail-pf1-f202.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726180AbfFUXRE (ORCPT ); Fri, 21 Jun 2019 19:17:04 -0400 Received: by mail-pf1-f202.google.com with SMTP id j7so5259106pfn.10 for ; Fri, 21 Jun 2019 16:17:03 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=x+zWoYb3OEB93ZrYqw2awl77D28JgmnclJmBViN44H4=; b=qcHkxnxf5Gif+xIe66suq0Hyr8+8rTvQnrtP2x5ScJ/8fSlsngFXNVuc+rpWwvdYm6 Wcp8+KJNrQbcIC4ZLOAzXwirkxVdKexkvo2JtLdwf+EgXbMWR+kIKVZrkphCAaRFKuW+ 6XW7fbRMRzPUPDun5drCj4gYodQCD7jID+T4Z6v8qNmFHFQWOuEAwQtaaQxDXYDPXFUi L2hed+keOQxUKIpxBkIoiSfL6Xng/VepBnisBn1lRygvdthSfM0nX5r8CkABcZVhY6A0 KdU+UJm3IzrbKATfPFk7XM4PYdoHxnaYVKIMfrgCVCkgOiKFReh3LmWdH6cDzsL2cOeE HJsg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=x+zWoYb3OEB93ZrYqw2awl77D28JgmnclJmBViN44H4=; b=Rfa0WDVS+K/xaLWrwJN4wS1TVCPqTxy96s/x7WW6Sow9+tnc0EhNikn5t14OcJTXPO emCI2yLRwkr1d9IOxFHUl1A3sKVG9+8fJbsWrN9dywNa+ZIpitILZ3NSVVnInqXhVxmJ tcumYfXaQzdV3M7c+FBOQ7EXcfy0XiZokF5OguScGGIOh0eGx2aKLIXOgIlmNhKkgZQw P8rPoy3DPL1/OQ1Dnzbw7Vx5vkCrxJwSbQv8UE6H7Q/WVm11+iaAPwy1wnl5DTjacVyW hPfwGXh1gJREXJ9CZEjtRAKon8bpbhhsW/aK/W5ATp+tNYL2K30U/ervNzaMjI29KtM2 g+4A== X-Gm-Message-State: APjAAAVcDa1Ow3kPL9BGxnWUd/QxEH4uc1v4iCbz02b/V5dcc5FkM7wD nYE3Vp6fTlO/s+duuw7RAnImmJbgwUbu X-Google-Smtp-Source: APXvYqyWAECXZ44hgTRRHVkPATT0twBiwRJNdAxtTkl8EHqayyqvXXCBWL8ktsc0JJnBYOw0O8xxrQNca70G X-Received: by 2002:a63:86c7:: with SMTP id x190mr15132914pgd.316.1561159023355; Fri, 21 Jun 2019 16:17:03 -0700 (PDT) Date: Fri, 21 Jun 2019 16:16:46 -0700 In-Reply-To: <20190621231650.32073-1-brianvv@google.com> Message-Id: <20190621231650.32073-3-brianvv@google.com> Mime-Version: 1.0 References: <20190621231650.32073-1-brianvv@google.com> X-Mailer: git-send-email 2.22.0.410.gd8fdbe21b5-goog Subject: [RFC PATCH 2/6] bpf: add BPF_MAP_DUMP command to access more than one entry per call From: Brian Vazquez To: Brian Vazquez , Alexei Starovoitov , Daniel Borkmann , "David S . Miller" Cc: Stanislav Fomichev , Willem de Bruijn , Petar Penkov , linux-kernel@vger.kernel.org, netdev@vger.kernel.org, bpf@vger.kernel.org, Brian Vazquez Content-Type: text/plain; charset="UTF-8" Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org This introduces a new command to retrieve a variable number of entries from a bpf map wrapping the existing bpf methods: map_get_next_key and map_lookup_elem Note that map_dump doesn't guarantee that reading the entire table is consistent since this function is always racing with kernel and user code but the same behaviour is found when the entire table is walked using the current interfaces: map_get_next_key + map_lookup_elem. It is also important to note that when a locked map is provided it is consistent only for 1 entry at the time, meaning that the buf returned might or might not be consistent. Suggested-by: Stanislav Fomichev Signed-off-by: Brian Vazquez --- include/uapi/linux/bpf.h | 9 ++++ kernel/bpf/syscall.c | 108 +++++++++++++++++++++++++++++++++++++++ 2 files changed, 117 insertions(+) diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index b077507efa3f3..1d753958874df 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -106,6 +106,7 @@ enum bpf_cmd { BPF_TASK_FD_QUERY, BPF_MAP_LOOKUP_AND_DELETE_ELEM, BPF_MAP_FREEZE, + BPF_MAP_DUMP, }; enum bpf_map_type { @@ -385,6 +386,14 @@ union bpf_attr { __u64 flags; }; + struct { /* struct used by BPF_MAP_DUMP command */ + __u32 map_fd; + __aligned_u64 prev_key; + __aligned_u64 buf; + __aligned_u64 buf_len; /* input/output: len of buf */ + __u64 flags; + } dump; + struct { /* anonymous struct used by BPF_PROG_LOAD command */ __u32 prog_type; /* one of enum bpf_prog_type */ __u32 insn_cnt; diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index a1823a50f9be0..7653346b5cfd1 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -1097,6 +1097,111 @@ static int map_get_next_key(union bpf_attr *attr) return err; } +/* last field in 'union bpf_attr' used by this command */ +#define BPF_MAP_DUMP_LAST_FIELD dump.buf_len + +static int map_dump(union bpf_attr *attr) +{ + void __user *ukey = u64_to_user_ptr(attr->dump.prev_key); + void __user *ubuf = u64_to_user_ptr(attr->dump.buf); + u32 __user *ubuf_len = u64_to_user_ptr(attr->dump.buf_len); + int ufd = attr->dump.map_fd; + struct bpf_map *map; + void *buf, *prev_key, *key, *value; + u32 value_size, elem_size, buf_len, cp_len; + struct fd f; + int err; + + if (CHECK_ATTR(BPF_MAP_DUMP)) + return -EINVAL; + + attr->flags = 0; + if (attr->dump.flags & ~BPF_F_LOCK) + return -EINVAL; + + f = fdget(ufd); + map = __bpf_map_get(f); + if (IS_ERR(map)) + return PTR_ERR(map); + if (!(map_get_sys_perms(map, f) & FMODE_CAN_READ)) { + err = -EPERM; + goto err_put; + } + + if ((attr->dump.flags & BPF_F_LOCK) && + !map_value_has_spin_lock(map)) { + err = -EINVAL; + goto err_put; + } + + if (map->map_type == BPF_MAP_TYPE_QUEUE || + map->map_type == BPF_MAP_TYPE_STACK) { + err = -ENOTSUPP; + goto err_put; + } + + value_size = bpf_map_value_size(map); + + err = get_user(buf_len, ubuf_len); + if (err) + goto err_put; + + elem_size = map->key_size + value_size; + if (buf_len < elem_size) { + err = -EINVAL; + goto err_put; + } + + if (ukey) { + prev_key = __bpf_copy_key(ukey, map->key_size); + if (IS_ERR(prev_key)) { + err = PTR_ERR(prev_key); + goto err_put; + } + } else { + prev_key = NULL; + } + + err = -ENOMEM; + buf = kmalloc(elem_size, GFP_USER | __GFP_NOWARN); + if (!buf) + goto err_put; + + key = buf; + value = key + map->key_size; + for (cp_len = 0; cp_len + elem_size <= buf_len ; cp_len += elem_size) { +next: + if (signal_pending(current)) { + err = -EINTR; + break; + } + + rcu_read_lock(); + err = map->ops->map_get_next_key(map, prev_key, key); + rcu_read_unlock(); + + if (err) + break; + + if (bpf_map_copy_value(map, key, value, attr->dump.flags)) + goto next; + + if (copy_to_user(ubuf + cp_len, buf, elem_size)) + break; + + prev_key = key; + } + + if (cp_len) + err = 0; + if (copy_to_user(ubuf_len, &cp_len, sizeof(cp_len))) + err = -EFAULT; + kfree(buf); +err_put: + fdput(f); + return err; +} + #define BPF_MAP_LOOKUP_AND_DELETE_ELEM_LAST_FIELD value static int map_lookup_and_delete_elem(union bpf_attr *attr) @@ -2891,6 +2996,9 @@ SYSCALL_DEFINE3(bpf, int, cmd, union bpf_attr __user *, uattr, unsigned int, siz case BPF_MAP_LOOKUP_AND_DELETE_ELEM: err = map_lookup_and_delete_elem(&attr); break; + case BPF_MAP_DUMP: + err = map_dump(&attr); + break; default: err = -EINVAL; break; -- 2.22.0.410.gd8fdbe21b5-goog