From patchwork Fri Apr 23 15:05:58 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Kumar Kartikeya Dwivedi X-Patchwork-Id: 12220761 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 X-Spam-Level: X-Spam-Status: No, score=-15.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham 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 79997C43460 for ; Fri, 23 Apr 2021 15:06:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 489EF61462 for ; Fri, 23 Apr 2021 15:06:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242801AbhDWPGp (ORCPT ); Fri, 23 Apr 2021 11:06:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50306 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242800AbhDWPGp (ORCPT ); Fri, 23 Apr 2021 11:06:45 -0400 Received: from mail-pg1-x542.google.com (mail-pg1-x542.google.com [IPv6:2607:f8b0:4864:20::542]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3079FC061574; Fri, 23 Apr 2021 08:06:09 -0700 (PDT) Received: by mail-pg1-x542.google.com with SMTP id y32so35375503pga.11; Fri, 23 Apr 2021 08:06:09 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=6PxbFNy4TwwhW0qk6KdqKgL8X0j6sxwiVkZ7z1Vo1yE=; b=rjNR0dJJSbzYynHDQeXZdsrn5PkuW3du6Hj3FjJ59Tg1tDHRbifZZ1fo44SSDEJtI2 sZXCbudVO1QoKi9YOKbDbQPGJqavL3HdbuSO5OucefiplySkzqPYSsctiqHHZQAZE5Vr Z+RGyQzzkErQ/bAgEThu/MATwGA5SRyBAogg1IF2BjTJoEJA1VBf1Z5OwDNYy73+B3tI EbYSX5xq79HQJcfv61mm2HmOuEagnFwPctpPcGCZyN49+mZTyzklrRE6TpSmHCqX7WVA WZwI1eIjeO/QCdQ3152S15qJav8OrilEcYpcz2//0pVQEM230YZfwI0pzQfcbSNCBRN2 coqA== 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=6PxbFNy4TwwhW0qk6KdqKgL8X0j6sxwiVkZ7z1Vo1yE=; b=uBCBGEUiwHVP9v5ASfK8lLmpt8UwGQJEob2tDQz456nENj+j0+ciFONGZp+LZj31XP 8mlxfC/TNy+WCuxjf/LJkcHbHtjElO950EjN0UMxGhupcK1QzEaeksL79fgQaQKW9FH1 +FhiDPIfeqa50dLteinVb4leqwdK2ZZZVnPehjV1UkZ6l2NgoFFzSteqrrEvF1McQWwN Vt20z6uIv0NhEKama7NxEp5zt6Q+or9yJ1/mbXeBUGILdTOa3TLZ+L40FjnhmPbC0HDW ZFFVZlRN8fFyq72tO2kyRqAF6IChpOMPUEivOzzAd5qV4y4Cm2b7f57uJuoiw03t6ybb ywRA== X-Gm-Message-State: AOAM532GpXSV4H7sBp8OGmyZqLGHDG6sMuWmIshIJ2nbdzMuVJ0VriQ+ lSRoiD+QUF+hmhqREl6g3l6rgpTu8+GCdw== X-Google-Smtp-Source: ABdhPJwjfDJnS5pl+yGG6e8e5EVy9S91Lqm3eArA508QoEmctZBH1cEoEUE+712BjWVSIa9vJtI2SQ== X-Received: by 2002:aa7:8c0e:0:b029:258:672e:9f86 with SMTP id c14-20020aa78c0e0000b0290258672e9f86mr4489346pfd.50.1619190368497; Fri, 23 Apr 2021 08:06:08 -0700 (PDT) Received: from localhost ([112.79.255.145]) by smtp.gmail.com with ESMTPSA id l1sm5460930pgt.29.2021.04.23.08.06.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 23 Apr 2021 08:06:08 -0700 (PDT) From: Kumar Kartikeya Dwivedi To: bpf@vger.kernel.org Cc: Kumar Kartikeya Dwivedi , =?utf-8?q?Toke_H=C3=B8iland-?= =?utf-8?q?J=C3=B8rgensen?= , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh , "David S. Miller" , Jakub Kicinski , Jesper Dangaard Brouer , netdev@vger.kernel.org Subject: [PATCH bpf-next v4 1/3] libbpf: add helpers for preparing netlink attributes Date: Fri, 23 Apr 2021 20:35:58 +0530 Message-Id: <20210423150600.498490-2-memxor@gmail.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210423150600.498490-1-memxor@gmail.com> References: <20210423150600.498490-1-memxor@gmail.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net This change introduces a few helpers to wrap open coded attribute preparation in netlink.c. Every nested attribute's closure must happen using the helper nlattr_end_nested, which sets its length properly. NLA_F_NESTED is enforced using nlattr_begin_nested helper. Other simple attributes can be added directly. The maxsz parameter corresponds to the size of the request structure which is being filled in, so for instance with req being: struct { struct nlmsghdr nh; struct tcmsg t; char buf[4096]; } req; Then, maxsz should be sizeof(req). This change also converts the open coded attribute preparation with the helpers. Note that the only failure the internal call to nlattr_add could result in the nested helper would be -EMSGSIZE, hence that is what we return to our caller. Reviewed-by: Toke Høiland-Jørgensen Signed-off-by: Kumar Kartikeya Dwivedi --- tools/lib/bpf/netlink.c | 37 ++++++++++++++----------------- tools/lib/bpf/nlattr.h | 48 +++++++++++++++++++++++++++++++++++++++++ 2 files changed, 64 insertions(+), 21 deletions(-) diff --git a/tools/lib/bpf/netlink.c b/tools/lib/bpf/netlink.c index d2cb28e9ef52..c79e30484e81 100644 --- a/tools/lib/bpf/netlink.c +++ b/tools/lib/bpf/netlink.c @@ -135,7 +135,7 @@ static int __bpf_set_link_xdp_fd_replace(int ifindex, int fd, int old_fd, __u32 flags) { int sock, seq = 0, ret; - struct nlattr *nla, *nla_xdp; + struct nlattr *nla; struct { struct nlmsghdr nh; struct ifinfomsg ifinfo; @@ -157,36 +157,31 @@ static int __bpf_set_link_xdp_fd_replace(int ifindex, int fd, int old_fd, req.ifinfo.ifi_index = ifindex; /* started nested attribute for XDP */ - nla = (struct nlattr *)(((char *)&req) - + NLMSG_ALIGN(req.nh.nlmsg_len)); - nla->nla_type = NLA_F_NESTED | IFLA_XDP; - nla->nla_len = NLA_HDRLEN; + nla = nlattr_begin_nested(&req.nh, sizeof(req), IFLA_XDP); + if (!nla) { + ret = -EMSGSIZE; + goto cleanup; + } /* add XDP fd */ - nla_xdp = (struct nlattr *)((char *)nla + nla->nla_len); - nla_xdp->nla_type = IFLA_XDP_FD; - nla_xdp->nla_len = NLA_HDRLEN + sizeof(int); - memcpy((char *)nla_xdp + NLA_HDRLEN, &fd, sizeof(fd)); - nla->nla_len += nla_xdp->nla_len; + ret = nlattr_add(&req.nh, sizeof(req), IFLA_XDP_FD, &fd, sizeof(fd)); + if (ret < 0) + goto cleanup; /* if user passed in any flags, add those too */ if (flags) { - nla_xdp = (struct nlattr *)((char *)nla + nla->nla_len); - nla_xdp->nla_type = IFLA_XDP_FLAGS; - nla_xdp->nla_len = NLA_HDRLEN + sizeof(flags); - memcpy((char *)nla_xdp + NLA_HDRLEN, &flags, sizeof(flags)); - nla->nla_len += nla_xdp->nla_len; + ret = nlattr_add(&req.nh, sizeof(req), IFLA_XDP_FLAGS, &flags, sizeof(flags)); + if (ret < 0) + goto cleanup; } if (flags & XDP_FLAGS_REPLACE) { - nla_xdp = (struct nlattr *)((char *)nla + nla->nla_len); - nla_xdp->nla_type = IFLA_XDP_EXPECTED_FD; - nla_xdp->nla_len = NLA_HDRLEN + sizeof(old_fd); - memcpy((char *)nla_xdp + NLA_HDRLEN, &old_fd, sizeof(old_fd)); - nla->nla_len += nla_xdp->nla_len; + ret = nlattr_add(&req.nh, sizeof(req), IFLA_XDP_EXPECTED_FD, &flags, sizeof(flags)); + if (ret < 0) + goto cleanup; } - req.nh.nlmsg_len += NLA_ALIGN(nla->nla_len); + nlattr_end_nested(&req.nh, nla); if (send(sock, &req, req.nh.nlmsg_len, 0) < 0) { ret = -errno; diff --git a/tools/lib/bpf/nlattr.h b/tools/lib/bpf/nlattr.h index 6cc3ac91690f..1c94cdb6e89d 100644 --- a/tools/lib/bpf/nlattr.h +++ b/tools/lib/bpf/nlattr.h @@ -10,7 +10,10 @@ #define __LIBBPF_NLATTR_H #include +#include +#include #include + /* avoid multiple definition of netlink features */ #define __LINUX_NETLINK_H @@ -103,4 +106,49 @@ int libbpf_nla_parse_nested(struct nlattr *tb[], int maxtype, int libbpf_nla_dump_errormsg(struct nlmsghdr *nlh); +static inline struct nlattr *nla_data(struct nlattr *nla) +{ + return (struct nlattr *)((char *)nla + NLA_HDRLEN); +} + +static inline struct nlattr *nh_tail(struct nlmsghdr *nh) +{ + return (struct nlattr *)((char *)nh + NLMSG_ALIGN(nh->nlmsg_len)); +} + +static inline int nlattr_add(struct nlmsghdr *nh, size_t maxsz, int type, + const void *data, int len) +{ + struct nlattr *nla; + + if (NLMSG_ALIGN(nh->nlmsg_len) + NLA_ALIGN(NLA_HDRLEN + len) > maxsz) + return -EMSGSIZE; + if ((!data && len) || (data && !len)) + return -EINVAL; + + nla = nh_tail(nh); + nla->nla_type = type; + nla->nla_len = NLA_HDRLEN + len; + if (data) + memcpy(nla_data(nla), data, len); + nh->nlmsg_len = NLMSG_ALIGN(nh->nlmsg_len) + NLA_ALIGN(nla->nla_len); + return 0; +} + +static inline struct nlattr *nlattr_begin_nested(struct nlmsghdr *nh, + size_t maxsz, int type) +{ + struct nlattr *tail; + + tail = nh_tail(nh); + if (nlattr_add(nh, maxsz, type | NLA_F_NESTED, NULL, 0)) + return NULL; + return tail; +} + +static inline void nlattr_end_nested(struct nlmsghdr *nh, struct nlattr *tail) +{ + tail->nla_len = (char *)nh_tail(nh) - (char *)tail; +} + #endif /* __LIBBPF_NLATTR_H */