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=-7.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 02E14C433DF for ; Sun, 28 Jun 2020 19:42:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C5842206A1 for ; Sun, 28 Jun 2020 19:42:53 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="aiOkAVVr" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726768AbgF1Tmx (ORCPT ); Sun, 28 Jun 2020 15:42:53 -0400 Received: from us-smtp-2.mimecast.com ([207.211.31.81]:26007 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726733AbgF1Tmw (ORCPT ); Sun, 28 Jun 2020 15:42:52 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1593373371; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=qn8LpID6vlMXVlee8uuBX1nH9942F9auzaGbi0XYOzY=; b=aiOkAVVrlRk0SPuJ9pBUE3w3FsTNxYex0pKcadpd1ENhGzkFMd0/HsLJVVjb86pK5VIqD4 8JroXtkQFgn9hNs4zjmENxigwNi6muQ76eqUlxkI7jwWHrkk1ieO3PVGYiMeADpTmsG30m 201liGxipqBPnbjph+jgCj8idPkvDaY= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-153-DRjyZkxOPie65meza3Aj7g-1; Sun, 28 Jun 2020 15:42:48 -0400 X-MC-Unique: DRjyZkxOPie65meza3Aj7g-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id A75E5107ACCA; Sun, 28 Jun 2020 19:42:46 +0000 (UTC) Received: from krava (unknown [10.40.192.56]) by smtp.corp.redhat.com (Postfix) with SMTP id 28EF85C1B2; Sun, 28 Jun 2020 19:42:42 +0000 (UTC) Date: Sun, 28 Jun 2020 21:42:42 +0200 From: Jiri Olsa To: Andrii Nakryiko Cc: Jiri Olsa , Alexei Starovoitov , Daniel Borkmann , Networking , bpf , Song Liu , Yonghong Song , Martin KaFai Lau , David Miller , John Fastabend , Wenbo Zhang , KP Singh , Andrii Nakryiko , Brendan Gregg , Florent Revest , Al Viro Subject: Re: [PATCH v4 bpf-next 10/14] bpf: Add d_path helper Message-ID: <20200628194242.GB2988321@krava> References: <20200625221304.2817194-1-jolsa@kernel.org> <20200625221304.2817194-11-jolsa@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Fri, Jun 26, 2020 at 01:38:27PM -0700, Andrii Nakryiko wrote: > On Thu, Jun 25, 2020 at 4:49 PM Jiri Olsa wrote: > > > > Adding d_path helper function that returns full path > > for give 'struct path' object, which needs to be the > > kernel BTF 'path' object. > > > > The helper calls directly d_path function. > > > > Updating also bpf.h tools uapi header and adding > > 'path' to bpf_helpers_doc.py script. > > > > Signed-off-by: Jiri Olsa > > --- > > include/uapi/linux/bpf.h | 14 +++++++++- > > kernel/trace/bpf_trace.c | 47 ++++++++++++++++++++++++++++++++++ > > scripts/bpf_helpers_doc.py | 2 ++ > > tools/include/uapi/linux/bpf.h | 14 +++++++++- > > 4 files changed, 75 insertions(+), 2 deletions(-) > > > > diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h > > index 0cb8ec948816..23274c81f244 100644 > > --- a/include/uapi/linux/bpf.h > > +++ b/include/uapi/linux/bpf.h > > @@ -3285,6 +3285,17 @@ union bpf_attr { > > * Dynamically cast a *sk* pointer to a *udp6_sock* pointer. > > * Return > > * *sk* if casting is valid, or NULL otherwise. > > + * > > + * int bpf_d_path(struct path *path, char *buf, u32 sz) > > + * Description > > + * Return full path for given 'struct path' object, which > > + * needs to be the kernel BTF 'path' object. The path is > > + * returned in buffer provided 'buf' of size 'sz'. > > + * > > + * Return > > + * length of returned string on success, or a negative > > + * error in case of failure > > It's important to note whether string is always zero-terminated (I'm > guessing it is, right?). right, will add > > > + * > > */ > > #define __BPF_FUNC_MAPPER(FN) \ > > FN(unspec), \ > > @@ -3427,7 +3438,8 @@ union bpf_attr { > > FN(skc_to_tcp_sock), \ > > FN(skc_to_tcp_timewait_sock), \ > > FN(skc_to_tcp_request_sock), \ > > - FN(skc_to_udp6_sock), > > + FN(skc_to_udp6_sock), \ > > + FN(d_path), > > > > /* integer value in 'imm' field of BPF_CALL instruction selects which helper > > * function eBPF program intends to call > > diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c > > index b124d468688c..6f31e21565b6 100644 > > --- a/kernel/trace/bpf_trace.c > > +++ b/kernel/trace/bpf_trace.c > > @@ -1060,6 +1060,51 @@ static const struct bpf_func_proto bpf_send_signal_thread_proto = { > > .arg1_type = ARG_ANYTHING, > > }; > > > > +BPF_CALL_3(bpf_d_path, struct path *, path, char *, buf, u32, sz) > > +{ > > + char *p = d_path(path, buf, sz - 1); > > + int len; > > + > > + if (IS_ERR(p)) { > > + len = PTR_ERR(p); > > + } else { > > + len = strlen(p); > > + if (len && p != buf) { > > + memmove(buf, p, len); > > + buf[len] = 0; > > if len above is zero, you won't zero-terminate it, so probably better > to move buf[len] = 0 out of if to do unconditionally good catch, will change > > > + } > > + } > > + > > + return len; > > +} > > + > > +BTF_SET_START(btf_whitelist_d_path) > > +BTF_ID(func, vfs_truncate) > > +BTF_ID(func, vfs_fallocate) > > +BTF_ID(func, dentry_open) > > +BTF_ID(func, vfs_getattr) > > +BTF_ID(func, filp_close) > > +BTF_SET_END(btf_whitelist_d_path) > > + > > +static bool bpf_d_path_allowed(const struct bpf_prog *prog) > > +{ > > + return btf_id_set_contains(&btf_whitelist_d_path, prog->aux->attach_btf_id); > > +} > > + > > This looks pretty great and clean, considering what's happening under > the covers. Nice work, thanks a lot! > > > +BTF_ID_LIST(bpf_d_path_btf_ids) > > +BTF_ID(struct, path) > > this is a bit more confusing to read and error-prone, but I couldn't > come up with any better way to do this... Still better than > alternatives. > > > + > > +static const struct bpf_func_proto bpf_d_path_proto = { > > + .func = bpf_d_path, > > + .gpl_only = true, > > Does it have to be GPL-only? What's the criteria? Sorry if this was > brought up previously. I don't think it's needed to be gpl_only, I'll set it to false thanks, jirka