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[2003:dc:6f0b:6500:529a:4cff:fe3d:d983]) by smtp.gmail.com with ESMTPSA id p10-20020a170906a00a00b00a0be4fec1b4sm1870231ejy.138.2023.12.01.04.56.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 01 Dec 2023 04:56:40 -0800 (PST) From: Max Kellermann To: Tejun Heo , Zefan Li , Johannes Weiner Cc: Max Kellermann , cgroups@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 1/2] kernel/cgroup: use kernfs_create_dir_ns() Date: Fri, 1 Dec 2023 13:56:37 +0100 Message-Id: <20231201125638.1699026-1-max.kellermann@ionos.com> X-Mailer: git-send-email 2.39.2 Precedence: bulk X-Mailing-List: cgroups@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit By passing the fsugid to kernfs_create_dir_ns(), we don't need cgroup_kn_set_ugid() any longer. That function was added for exactly this purpose by commit 49957f8e2a ("cgroup: newly created dirs and files should be owned by the creator"). Eliminating this piece of duplicate code means we benefit from future improvements to kernfs_create_dir_ns(); for example, both are lacking S_ISGID support currently, which my next patch will add to kernfs_create_dir_ns(). It cannot (easily) be added to cgroup_kn_set_ugid() because we can't dereference struct kernfs_iattrs from there. Signed-off-by: Max Kellermann --- kernel/cgroup/cgroup.c | 31 ++++--------------------------- 1 file changed, 4 insertions(+), 27 deletions(-) diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c index 4b9ff41ca603..a844b421fd83 100644 --- a/kernel/cgroup/cgroup.c +++ b/kernel/cgroup/cgroup.c @@ -4169,20 +4169,6 @@ static struct kernfs_ops cgroup_kf_ops = { .seq_show = cgroup_seqfile_show, }; -/* set uid and gid of cgroup dirs and files to that of the creator */ -static int cgroup_kn_set_ugid(struct kernfs_node *kn) -{ - struct iattr iattr = { .ia_valid = ATTR_UID | ATTR_GID, - .ia_uid = current_fsuid(), - .ia_gid = current_fsgid(), }; - - if (uid_eq(iattr.ia_uid, GLOBAL_ROOT_UID) && - gid_eq(iattr.ia_gid, GLOBAL_ROOT_GID)) - return 0; - - return kernfs_setattr(kn, &iattr); -} - static void cgroup_file_notify_timer(struct timer_list *timer) { cgroup_file_notify(container_of(timer, struct cgroup_file, @@ -4195,25 +4181,18 @@ static int cgroup_add_file(struct cgroup_subsys_state *css, struct cgroup *cgrp, char name[CGROUP_FILE_NAME_MAX]; struct kernfs_node *kn; struct lock_class_key *key = NULL; - int ret; #ifdef CONFIG_DEBUG_LOCK_ALLOC key = &cft->lockdep_key; #endif kn = __kernfs_create_file(cgrp->kn, cgroup_file_name(cgrp, cft, name), cgroup_file_mode(cft), - GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, + current_fsuid(), current_fsgid(), 0, cft->kf_ops, cft, NULL, key); if (IS_ERR(kn)) return PTR_ERR(kn); - ret = cgroup_kn_set_ugid(kn); - if (ret) { - kernfs_remove(kn); - return ret; - } - if (cft->file_offset) { struct cgroup_file *cfile = (void *)css + cft->file_offset; @@ -5616,7 +5595,9 @@ static struct cgroup *cgroup_create(struct cgroup *parent, const char *name, goto out_cancel_ref; /* create the directory */ - kn = kernfs_create_dir(parent->kn, name, mode, cgrp); + kn = kernfs_create_dir_ns(parent->kn, name, mode, + current_fsuid(), current_fsgid(), + cgrp, NULL); if (IS_ERR(kn)) { ret = PTR_ERR(kn); goto out_stat_exit; @@ -5761,10 +5742,6 @@ int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name, umode_t mode) */ kernfs_get(cgrp->kn); - ret = cgroup_kn_set_ugid(cgrp->kn); - if (ret) - goto out_destroy; - ret = css_populate_dir(&cgrp->self); if (ret) goto out_destroy; -- 2.39.2