From patchwork Thu Nov 24 15:15:55 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Benjamin Tissoires X-Patchwork-Id: 628721 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B1CD1C43217 for ; Thu, 24 Nov 2022 15:18:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229975AbiKXPSG (ORCPT ); Thu, 24 Nov 2022 10:18:06 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57404 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229953AbiKXPSC (ORCPT ); Thu, 24 Nov 2022 10:18:02 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4677116E8D8 for ; Thu, 24 Nov 2022 07:16:21 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1669302980; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=1gSBxJ3JD+Lhw0lQsSl13cc2SNWiLM1GIUzZ7OkQbMU=; b=A+tYn6JYB9UApKhsM/aaoZ16zkAhLFdJvsz+4MZTla7o1Ym4e7G4iRom3zZPFscVHIVNtB MiSmWfN3g60msFKRIBxUJjPSsHYYjvtNkOVE28wLIqnKm3yG2x9MTq499IRvXqxasDo9vu Rd/M+7L1PwHE6fBybMNFgR8T9b7bPoQ= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-9-2nluelRgODCohAjC4AFX6g-1; Thu, 24 Nov 2022 10:16:14 -0500 X-MC-Unique: 2nluelRgODCohAjC4AFX6g-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.rdu2.redhat.com [10.11.54.1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 87F903C01E03; Thu, 24 Nov 2022 15:16:13 +0000 (UTC) Received: from plouf.redhat.com (unknown [10.39.193.200]) by smtp.corp.redhat.com (Postfix) with ESMTP id C7AEF40C2064; Thu, 24 Nov 2022 15:16:11 +0000 (UTC) From: Benjamin Tissoires To: Greg KH , Jiri Kosina , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Dmitry Torokhov Cc: Tero Kristo , linux-kernel@vger.kernel.org, linux-input@vger.kernel.org, netdev@vger.kernel.org, bpf@vger.kernel.org, Benjamin Tissoires Subject: [RFC hid v1 02/10] WIP: bpf: allow to pin programs from the kernel when bpffs is mounted Date: Thu, 24 Nov 2022 16:15:55 +0100 Message-Id: <20221124151603.807536-3-benjamin.tissoires@redhat.com> In-Reply-To: <20221124151603.807536-1-benjamin.tissoires@redhat.com> References: <20221124151603.807536-1-benjamin.tissoires@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.1 Precedence: bulk List-ID: X-Mailing-List: linux-input@vger.kernel.org I want to be able to pin programs loaded by the kernel and expose them through the bpffs so userspace knows what is loaded. There are a few things missings in this WIP: - locking on bpffs_sb - ability to create a hierarchy from the kernel: I'd like to store all of my programs in /sys/fs/bpf/hid, not everything at the root of the mount - ability to store programs when bpffs is not mounted Signed-off-by: Benjamin Tissoires --- include/linux/bpf.h | 1 + kernel/bpf/inode.c | 41 ++++++++++++++++++++++++++++++++++++++++- 2 files changed, 41 insertions(+), 1 deletion(-) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 0566705c1d4e..f5a7dca520eb 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -1806,6 +1806,7 @@ struct bpf_link *bpf_link_get_curr_or_next(u32 *id); int bpf_obj_pin_user(u32 ufd, const char __user *pathname); int bpf_obj_get_user(const char __user *pathname, int flags); +int bpf_prog_pin_kernel(const char *name, struct bpf_prog *prog); #define BPF_ITER_FUNC_PREFIX "bpf_iter_" #define DEFINE_BPF_ITER_FUNC(target, args...) \ diff --git a/kernel/bpf/inode.c b/kernel/bpf/inode.c index 4f841e16779e..7be24ffad7f7 100644 --- a/kernel/bpf/inode.c +++ b/kernel/bpf/inode.c @@ -29,6 +29,9 @@ enum bpf_type { BPF_TYPE_LINK, }; + +static struct super_block *bpffs_sb; + static void *bpf_any_get(void *raw, enum bpf_type type) { switch (type) { @@ -435,6 +438,34 @@ static int bpf_iter_link_pin_kernel(struct dentry *parent, return ret; } +/* pin a program in the bpffs */ +/* TODO: handle path relative to mount point instead of plain name by recreating + * the hierarchy, like in drivers/base/devtmpfs.c + */ +int bpf_prog_pin_kernel(const char *name, struct bpf_prog *prog) +{ + struct dentry *parent; + umode_t mode = S_IFREG | S_IRUSR; + struct dentry *dentry; + int ret; + + if (!bpffs_sb) + return -ENOENT; + + parent = bpffs_sb->s_root; + + inode_lock(parent->d_inode); + dentry = lookup_one_len(name, parent, strlen(name)); + if (IS_ERR(dentry)) { + inode_unlock(parent->d_inode); + return PTR_ERR(dentry); + } + ret = bpf_mkprog(dentry, mode, prog); + dput(dentry); + inode_unlock(parent->d_inode); + return ret; +} + static int bpf_obj_do_pin(const char __user *pathname, void *raw, enum bpf_type type) { @@ -758,6 +789,8 @@ static int bpf_fill_super(struct super_block *sb, struct fs_context *fc) inode->i_mode &= ~S_IALLUGO; populate_bpffs(sb->s_root); inode->i_mode |= S_ISVTX | opts->mode; + + bpffs_sb = sb; return 0; } @@ -795,12 +828,18 @@ static int bpf_init_fs_context(struct fs_context *fc) return 0; } +static void bpf_kill_sb(struct super_block *sb) +{ + bpffs_sb = NULL; + kill_litter_super(sb); +} + static struct file_system_type bpf_fs_type = { .owner = THIS_MODULE, .name = "bpf", .init_fs_context = bpf_init_fs_context, .parameters = bpf_fs_parameters, - .kill_sb = kill_litter_super, + .kill_sb = bpf_kill_sb, }; static int __init bpf_init(void)