From patchwork Tue Feb 23 18:49:28 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Cong Wang X-Patchwork-Id: 387122 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, URIBL_BLOCKED, USER_AGENT_GIT 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 190BAC433E6 for ; Tue, 23 Feb 2021 18:51:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E513A64E22 for ; Tue, 23 Feb 2021 18:51:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233352AbhBWSuw (ORCPT ); Tue, 23 Feb 2021 13:50:52 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57036 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233405AbhBWSu3 (ORCPT ); Tue, 23 Feb 2021 13:50:29 -0500 Received: from mail-oi1-x235.google.com (mail-oi1-x235.google.com [IPv6:2607:f8b0:4864:20::235]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 84D94C06178A; Tue, 23 Feb 2021 10:49:49 -0800 (PST) Received: by mail-oi1-x235.google.com with SMTP id l64so5903109oig.9; Tue, 23 Feb 2021 10:49:49 -0800 (PST) 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=yXSdJhcfJca2aHrUW7nbcpmkhzySeq2lXG5UhhU0x4M=; b=JuQrYzjXHfxebJ4kXT7IIUdB6vJxv95Dp/DpcF+VszqeBvzPS7OXrhfIyWGWkkhuUt Y66m8b89OxkYKSNqZCEGbQfSlFuHmXT6ErDtNIoHx56yMQepi4k2bauHCfJZwJh1u/hs RvH/k0GkaQ3y7gBu3r25yB7xzDbGQM3KiuIbn20T7pTz+C99FHMGWkrshAOqvdgd8b4I ACkc0XHP6CWNhnXxd6+3tTRIymGmbeCoNHlhCysCaG89YfdFbqZvl9AOcrkuBT5yPXaW AaN77MSjOsDPVdWcAokXyeL+OEH058qyPcQV9QkepW1CTKj3HnJ2a8NE76Mg8VRKOoR+ 1uxg== 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=yXSdJhcfJca2aHrUW7nbcpmkhzySeq2lXG5UhhU0x4M=; b=BWzKWghNRpojNvgH0+hb4WinZb5Ksv+cEYdPn6HYeZIXAdEWv570DxKONXl/1Hf38R 97eNwYe2Gok0L6oUHvmtGHYGNx1t8pec3pg5ugZwkYtXEjx0eZe73lXdE44SqUtE1Ql8 VrJJRgebUweg//h5zORISsmEGyBfKm2XoAms+qVUqeGI3XPNVBds9trfpNM6gc32rGmB fUZ2yJIIK6oI1c7aZzHRoXVUAuhzH77jW54yXAtKUMleTB/gj399i15uQi9nc+4lv78E 8Fq9CjzDPPSmbQAUC8Q3NyhNo8zUyV5pd/OorzTkc207PBeHiJSiXcooGIBzgJek6bm2 upyA== X-Gm-Message-State: AOAM532WXTQjXoH70ezMEGbSXzVA1s30yqnxslTyFVdT7/99nBPjvio+ 0WDuz2i7oj/LN+zD6t4Xuc5wrxR1e7Ylww== X-Google-Smtp-Source: ABdhPJzgbytzVAgH9C609DMa40QsBJbsNjT8dgXIop/AqSChWLr9X7/e6AHin0IUK0ua8INQksqbcw== X-Received: by 2002:aca:5882:: with SMTP id m124mr99976oib.137.1614106188769; Tue, 23 Feb 2021 10:49:48 -0800 (PST) Received: from unknown.attlocal.net ([2600:1700:65a0:ab60:4543:ab2:3bf6:ce41]) by smtp.gmail.com with ESMTPSA id p12sm4387094oon.12.2021.02.23.10.49.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 23 Feb 2021 10:49:48 -0800 (PST) From: Cong Wang To: netdev@vger.kernel.org Cc: bpf@vger.kernel.org, duanxiongchun@bytedance.com, wangdongdong.6@bytedance.com, jiang.wang@bytedance.com, Cong Wang , Jakub Sitnicki , Daniel Borkmann , Lorenz Bauer , John Fastabend Subject: [Patch bpf-next v7 3/9] bpf: compute data_end dynamically with JIT code Date: Tue, 23 Feb 2021 10:49:28 -0800 Message-Id: <20210223184934.6054-4-xiyou.wangcong@gmail.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210223184934.6054-1-xiyou.wangcong@gmail.com> References: <20210223184934.6054-1-xiyou.wangcong@gmail.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Cong Wang Currently, we compute ->data_end with a compile-time constant offset of skb. But as Jakub pointed out, we can actually compute it in eBPF JIT code at run-time, so that we can competely get rid of ->data_end. This is similar to skb_shinfo(skb) computation in bpf_convert_shinfo_access(). Suggested-by: Jakub Sitnicki Cc: Daniel Borkmann Cc: Lorenz Bauer Acked-by: John Fastabend Acked-by: Jakub Sitnicki Signed-off-by: Cong Wang --- include/net/tcp.h | 6 ------ net/core/filter.c | 48 +++++++++++++++++++++++++++-------------------- net/core/skmsg.c | 1 - 3 files changed, 28 insertions(+), 27 deletions(-) diff --git a/include/net/tcp.h b/include/net/tcp.h index c00e125dcfb9..947ef5da6867 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -886,18 +886,12 @@ struct tcp_skb_cb { struct { __u32 flags; struct sock *sk_redir; - void *data_end; } bpf; }; }; #define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0])) -static inline void bpf_compute_data_end_sk_skb(struct sk_buff *skb) -{ - TCP_SKB_CB(skb)->bpf.data_end = skb->data + skb_headlen(skb); -} - static inline bool tcp_skb_bpf_ingress(const struct sk_buff *skb) { return TCP_SKB_CB(skb)->bpf.flags & BPF_F_INGRESS; diff --git a/net/core/filter.c b/net/core/filter.c index adfdad234674..13bcf248ee7b 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -1863,10 +1863,7 @@ static const struct bpf_func_proto bpf_sk_fullsock_proto = { static inline int sk_skb_try_make_writable(struct sk_buff *skb, unsigned int write_len) { - int err = __bpf_try_make_writable(skb, write_len); - - bpf_compute_data_end_sk_skb(skb); - return err; + return __bpf_try_make_writable(skb, write_len); } BPF_CALL_2(sk_skb_pull_data, struct sk_buff *, skb, u32, len) @@ -3577,7 +3574,6 @@ BPF_CALL_4(sk_skb_adjust_room, struct sk_buff *, skb, s32, len_diff, return -ENOMEM; __skb_pull(skb, len_diff_abs); } - bpf_compute_data_end_sk_skb(skb); if (tls_sw_has_ctx_rx(skb->sk)) { struct strp_msg *rxm = strp_msg(skb); @@ -3742,10 +3738,7 @@ static const struct bpf_func_proto bpf_skb_change_tail_proto = { BPF_CALL_3(sk_skb_change_tail, struct sk_buff *, skb, u32, new_len, u64, flags) { - int ret = __bpf_skb_change_tail(skb, new_len, flags); - - bpf_compute_data_end_sk_skb(skb); - return ret; + return __bpf_skb_change_tail(skb, new_len, flags); } static const struct bpf_func_proto sk_skb_change_tail_proto = { @@ -3808,10 +3801,7 @@ static const struct bpf_func_proto bpf_skb_change_head_proto = { BPF_CALL_3(sk_skb_change_head, struct sk_buff *, skb, u32, head_room, u64, flags) { - int ret = __bpf_skb_change_head(skb, head_room, flags); - - bpf_compute_data_end_sk_skb(skb); - return ret; + return __bpf_skb_change_head(skb, head_room, flags); } static const struct bpf_func_proto sk_skb_change_head_proto = { @@ -9655,22 +9645,40 @@ static u32 sock_ops_convert_ctx_access(enum bpf_access_type type, return insn - insn_buf; } +/* data_end = skb->data + skb_headlen() */ +static struct bpf_insn *bpf_convert_data_end_access(const struct bpf_insn *si, + struct bpf_insn *insn) +{ + /* si->dst_reg = skb->data */ + *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct sk_buff, data), + si->dst_reg, si->src_reg, + offsetof(struct sk_buff, data)); + /* AX = skb->len */ + *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct sk_buff, len), + BPF_REG_AX, si->src_reg, + offsetof(struct sk_buff, len)); + /* si->dst_reg = skb->data + skb->len */ + *insn++ = BPF_ALU64_REG(BPF_ADD, si->dst_reg, BPF_REG_AX); + /* AX = skb->data_len */ + *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct sk_buff, data_len), + BPF_REG_AX, si->src_reg, + offsetof(struct sk_buff, data_len)); + /* si->dst_reg = skb->data + skb->len - skb->data_len */ + *insn++ = BPF_ALU64_REG(BPF_SUB, si->dst_reg, BPF_REG_AX); + + return insn; +} + static u32 sk_skb_convert_ctx_access(enum bpf_access_type type, const struct bpf_insn *si, struct bpf_insn *insn_buf, struct bpf_prog *prog, u32 *target_size) { struct bpf_insn *insn = insn_buf; - int off; switch (si->off) { case offsetof(struct __sk_buff, data_end): - off = si->off; - off -= offsetof(struct __sk_buff, data_end); - off += offsetof(struct sk_buff, cb); - off += offsetof(struct tcp_skb_cb, bpf.data_end); - *insn++ = BPF_LDX_MEM(BPF_SIZEOF(void *), si->dst_reg, - si->src_reg, off); + insn = bpf_convert_data_end_access(si, insn); break; default: return bpf_convert_ctx_access(type, si, insn_buf, prog, diff --git a/net/core/skmsg.c b/net/core/skmsg.c index d00c9a4b47e7..8822001ab3dc 100644 --- a/net/core/skmsg.c +++ b/net/core/skmsg.c @@ -746,7 +746,6 @@ EXPORT_SYMBOL_GPL(sk_psock_msg_verdict); static int sk_psock_bpf_run(struct sk_psock *psock, struct bpf_prog *prog, struct sk_buff *skb) { - bpf_compute_data_end_sk_skb(skb); return bpf_prog_run_pin_on_cpu(prog, skb); }