From patchwork Mon Feb 24 17:21:02 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christian Brauner X-Patchwork-Id: 11401127 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 78A4192A for ; Mon, 24 Feb 2020 17:21:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6291D21744 for ; Mon, 24 Feb 2020 17:21:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727440AbgBXRV4 (ORCPT ); Mon, 24 Feb 2020 12:21:56 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:57088 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727968AbgBXRVZ (ORCPT ); Mon, 24 Feb 2020 12:21:25 -0500 Received: from ip5f5bf7ec.dynamic.kabel-deutschland.de ([95.91.247.236] helo=wittgenstein.fritz.box) by youngberry.canonical.com with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.86_2) (envelope-from ) id 1j6HQ1-0004D9-Ls; Mon, 24 Feb 2020 17:21:21 +0000 From: Christian Brauner To: "David S. Miller" , Greg Kroah-Hartman , linux-kernel@vger.kernel.org, netdev@vger.kernel.org Cc: "Rafael J. Wysocki" , Pavel Machek , Jakub Kicinski , Eric Dumazet , Stephen Hemminger , linux-pm@vger.kernel.org, Christian Brauner Subject: [PATCH v4 1/9] sysfs: add sysfs_file_change_owner_by_name() Date: Mon, 24 Feb 2020 18:21:02 +0100 Message-Id: <20200224172110.4121492-2-christian.brauner@ubuntu.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200224172110.4121492-1-christian.brauner@ubuntu.com> References: <20200224172110.4121492-1-christian.brauner@ubuntu.com> MIME-Version: 1.0 Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org Add helpers to change the owner of a sysfs files. This function will be used to correctly account for kobject ownership changes, e.g. when moving network devices between network namespaces. Signed-off-by: Christian Brauner --- /* v2 */ - Greg Kroah-Hartman : - Better naming for sysfs_file_change_owner() to reflect the fact that it can be used to change the owner of the kobject itself by passing NULL as argument. - Christian Brauner : - Split sysfs_file_change_owner() into two helpers sysfs_change_owner() and sysfs_change_owner_by_name(). The former changes the owner of the kobject itself, the latter the owner of the kobject looked up via the name argument. /* v3 */ - Greg Kroah-Hartman : - Add explicit uid/gid parameters. /* v4 */ - Greg Kroah-Hartman : - Remove the second helper which changes the ownership of the kobject itself and do it in-place instead later on in the series. A separate helper is not needed for that. - Christian Brauner : - Add more documentation. --- fs/sysfs/file.c | 47 +++++++++++++++++++++++++++++++++++++++++++ include/linux/sysfs.h | 10 +++++++++ 2 files changed, 57 insertions(+) diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c index 130fc6fbcc03..4ca936ca3ba4 100644 --- a/fs/sysfs/file.c +++ b/fs/sysfs/file.c @@ -558,3 +558,50 @@ void sysfs_remove_bin_file(struct kobject *kobj, kernfs_remove_by_name(kobj->sd, attr->attr.name); } EXPORT_SYMBOL_GPL(sysfs_remove_bin_file); + +static int internal_change_owner(struct kernfs_node *kn, kuid_t kuid, + kgid_t kgid) +{ + struct iattr newattrs = { + .ia_valid = ATTR_UID | ATTR_GID, + .ia_uid = kuid, + .ia_gid = kgid, + }; + return kernfs_setattr(kn, &newattrs); +} + +/** + * sysfs_file_change_owner - change owner of a sysfs file. + * @kobj: object. + * @name: name of the file to change. + * @kuid: new owner's kuid + * @kgid: new owner's kgid + * + * This function looks up the sysfs entry @name under @kobj and changes the + * ownership to @kuid/@kgid. + * + * Returns 0 on success or error code on failure. + */ +int sysfs_file_change_owner(struct kobject *kobj, const char *name, kuid_t kuid, + kgid_t kgid) +{ + struct kernfs_node *kn; + int error; + + if (!name) + return -EINVAL; + + if (!kobj->state_in_sysfs) + return -EINVAL; + + kn = kernfs_find_and_get(kobj->sd, name); + if (!kn) + return -ENOENT; + + error = internal_change_owner(kn, kuid, kgid); + + kernfs_put(kn); + + return error; +} +EXPORT_SYMBOL_GPL(sysfs_file_change_owner); diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h index fa7ee503fb76..a7884024a911 100644 --- a/include/linux/sysfs.h +++ b/include/linux/sysfs.h @@ -310,6 +310,9 @@ static inline void sysfs_enable_ns(struct kernfs_node *kn) return kernfs_enable_ns(kn); } +int sysfs_file_change_owner(struct kobject *kobj, const char *name, kuid_t kuid, + kgid_t kgid); + #else /* CONFIG_SYSFS */ static inline int sysfs_create_dir_ns(struct kobject *kobj, const void *ns) @@ -522,6 +525,13 @@ static inline void sysfs_enable_ns(struct kernfs_node *kn) { } +static inline int sysfs_file_change_owner(struct kobject *kobj, + const char *name, kuid_t kuid, + kgid_t kgid) +{ + return 0; +} + #endif /* CONFIG_SYSFS */ static inline int __must_check sysfs_create_file(struct kobject *kobj,