From patchwork Thu Jun 27 20:24:13 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Brian Vazquez X-Patchwork-Id: 1123615 X-Patchwork-Delegate: bpf@iogearbox.net Return-Path: X-Original-To: incoming-bpf@patchwork.ozlabs.org Delivered-To: patchwork-incoming-bpf@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=none (mailfrom) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=bpf-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=google.com header.i=@google.com header.b="ejPABeh3"; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 45ZWbF6Dzzz9s4V for ; Fri, 28 Jun 2019 06:24:41 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726604AbfF0UYk (ORCPT ); Thu, 27 Jun 2019 16:24:40 -0400 Received: from mail-ua1-f73.google.com ([209.85.222.73]:44414 "EHLO mail-ua1-f73.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726603AbfF0UYj (ORCPT ); Thu, 27 Jun 2019 16:24:39 -0400 Received: by mail-ua1-f73.google.com with SMTP id p13so484818uad.11 for ; Thu, 27 Jun 2019 13:24:39 -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=ejPABeh3HrJ5MjI0uvNPsR3WpKL0QNP2sf8hcWcK8q1KuOiJ1bnwbsj8cYVD+jZEWR nDgVwuXMCiRc1jg5oCWXufqQcrtrj/1u2ZEnFXLbOtR7I22u5EoLvGmt/p2fAZmqp2rB jnpTkM+MDpcTUM5TebWW8yfpcl8lIxvN6YRsCsg++gK1017NVXPjXQvnjspLWqv+NC5H YGvgfwaIu8/NsQ9EdSa51EDM3WRhw9DBWkS6bMLRhKeaC1+Yt2s4NMEXkz820GwEtDFh DsiEbi2xxyxu5Wsqsm8nXo0ZZIMkBb++iFM/Xp0A1BCFPQVo3rJwfdM2BI+IXtpXjOOR cR4w== 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=tLr0Yx3BW5Da6CurNEoXIdmkbz+UjsfTkyYYHr80s0PQa5dyIsWz9vJF+CCekazdol QIsdud1Ri1FNaQ5WXYbMGtVYcvBA2U4J6sCU0lkkqLpz0U/xmadl47ye4sg6ZMjLKYz5 39SHJEQWfpJLLhyosYYDEwO2HXyaUntTWh0m+IweoovzCtEpEL/c2ikL0az/0EpscDYc jLgvPTPJc55P02XOqJNAmlwBTUr4rWLPE/MfIbaWFrpzvl67CNVXnf/SL1sQp20UmOdm kj+/oOcwrf81J5d3XtgzRg38zReqkC3OiBkvvfYG16oohInOde70mLjXBpHyKQLwWtY8 9DGQ== X-Gm-Message-State: APjAAAVi1RanQ/eGA/EbfkcWqANImQIzoFvK/ykIq8xtRV+fd334ADdI qZ5Kx+Bu6fA8JjkrnnRXuRDjS/kW+C0T X-Google-Smtp-Source: APXvYqyuQgvuJ1yFYSQDnjt0mvywRc4BGtTMrY5kgm7wbtoBF/+fzc2RSJE/ie8lWBaVnk//3C9fe16w4LI7 X-Received: by 2002:a67:7a90:: with SMTP id v138mr4015150vsc.200.1561667078376; Thu, 27 Jun 2019 13:24:38 -0700 (PDT) Date: Thu, 27 Jun 2019 13:24:13 -0700 In-Reply-To: <20190627202417.33370-1-brianvv@google.com> Message-Id: <20190627202417.33370-3-brianvv@google.com> Mime-Version: 1.0 References: <20190627202417.33370-1-brianvv@google.com> X-Mailer: git-send-email 2.22.0.410.gd8fdbe21b5-goog Subject: [RFC PATCH bpf-next v2 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 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;