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kernel/cgroup: use kernfs_create_dir_ns()

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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.

--
v1 -> v2: 12-digit commit id

Signed-off-by: Max Kellermann <max.kellermann@ionos.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20231208093310.297233-1-max.kellermann@ionos.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Max Kellermann 2023-12-08 10:33:09 +01:00 committed by Greg Kroah-Hartman
parent 7c23fb2e6e
commit fe3de0102b
1 changed files with 4 additions and 27 deletions
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31
kernel/cgroup/cgroup.c
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@ -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;