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kernfs: allow creating kernfs objects with arbitrary uid/gid

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This change allows creating kernfs files and directories with arbitrary
uid/gid instead of always using GLOBAL_ROOT_UID/GID by extending
kernfs_create_dir_ns() and kernfs_create_file_ns() with uid/gid arguments.
The "simple" kernfs_create_file() and kernfs_create_dir() are left alone
and always create objects belonging to the global root.

When creating symlinks ownership (uid/gid) is taken from the target kernfs
object.

Co-Developed-by: Tyler Hicks <tyhicks@canonical.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Dmitry Torokhov 2018-07-20 21:56:47 +00:00 committed by David S. Miller
parent 7c4ec749a3
commit 488dee96bb
10 changed files with 76 additions and 21 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
View File

@ -146,6 +146,7 @@ static int rdtgroup_add_file(struct kernfs_node *parent_kn, struct rftype *rft)
int ret;
kn = __kernfs_create_file(parent_kn, rft->name, rft->mode,
GLOBAL_ROOT_UID, GLOBAL_ROOT_GID,
0, rft->kf_ops, rft, NULL, NULL);
if (IS_ERR(kn))
return PTR_ERR(kn);
@ -1503,7 +1504,8 @@ static int mon_addfile(struct kernfs_node *parent_kn, const char *name,
struct kernfs_node *kn;
int ret = 0;
kn = __kernfs_create_file(parent_kn, name, 0444, 0,
kn = __kernfs_create_file(parent_kn, name, 0444,
GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, 0,
&kf_mondata_ops, priv, NULL, NULL);
if (IS_ERR(kn))
return PTR_ERR(kn);

29
fs/kernfs/dir.c
View File

@ -619,6 +619,7 @@ struct kernfs_node *kernfs_node_from_dentry(struct dentry *dentry)
static struct kernfs_node *__kernfs_new_node(struct kernfs_root *root,
const char *name, umode_t mode,
kuid_t uid, kgid_t gid,
unsigned flags)
{
struct kernfs_node *kn;
@ -661,8 +662,22 @@ static struct kernfs_node *__kernfs_new_node(struct kernfs_root *root,
kn->mode = mode;
kn->flags = flags;
if (!uid_eq(uid, GLOBAL_ROOT_UID) || !gid_eq(gid, GLOBAL_ROOT_GID)) {
struct iattr iattr = {
.ia_valid = ATTR_UID | ATTR_GID,
.ia_uid = uid,
.ia_gid = gid,
};
ret = __kernfs_setattr(kn, &iattr);
if (ret < 0)
goto err_out3;
}
return kn;
err_out3:
idr_remove(&root->ino_idr, kn->id.ino);
err_out2:
kmem_cache_free(kernfs_node_cache, kn);
err_out1:
@ -672,11 +687,13 @@ static struct kernfs_node *__kernfs_new_node(struct kernfs_root *root,
struct kernfs_node *kernfs_new_node(struct kernfs_node *parent,
const char *name, umode_t mode,
kuid_t uid, kgid_t gid,
unsigned flags)
{
struct kernfs_node *kn;
kn = __kernfs_new_node(kernfs_root(parent), name, mode, flags);
kn = __kernfs_new_node(kernfs_root(parent),
name, mode, uid, gid, flags);
if (kn) {
kernfs_get(parent);
kn->parent = parent;
@ -946,6 +963,7 @@ struct kernfs_root *kernfs_create_root(struct kernfs_syscall_ops *scops,
root->next_generation = 1;
kn = __kernfs_new_node(root, "", S_IFDIR | S_IRUGO | S_IXUGO,
GLOBAL_ROOT_UID, GLOBAL_ROOT_GID,
KERNFS_DIR);
if (!kn) {
idr_destroy(&root->ino_idr);
@ -984,6 +1002,8 @@ void kernfs_destroy_root(struct kernfs_root *root)
* @parent: parent in which to create a new directory
* @name: name of the new directory
* @mode: mode of the new directory
* @uid: uid of the new directory
* @gid: gid of the new directory
* @priv: opaque data associated with the new directory
* @ns: optional namespace tag of the directory
*
@ -991,13 +1011,15 @@ void kernfs_destroy_root(struct kernfs_root *root)
*/
struct kernfs_node *kernfs_create_dir_ns(struct kernfs_node *parent,
const char *name, umode_t mode,
kuid_t uid, kgid_t gid,
void *priv, const void *ns)
{
struct kernfs_node *kn;
int rc;
/* allocate */
kn = kernfs_new_node(parent, name, mode | S_IFDIR, KERNFS_DIR);
kn = kernfs_new_node(parent, name, mode | S_IFDIR,
uid, gid, KERNFS_DIR);
if (!kn)
return ERR_PTR(-ENOMEM);
@ -1028,7 +1050,8 @@ struct kernfs_node *kernfs_create_empty_dir(struct kernfs_node *parent,
int rc;
/* allocate */
kn = kernfs_new_node(parent, name, S_IRUGO|S_IXUGO|S_IFDIR, KERNFS_DIR);
kn = kernfs_new_node(parent, name, S_IRUGO|S_IXUGO|S_IFDIR,
GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, KERNFS_DIR);
if (!kn)
return ERR_PTR(-ENOMEM);

8
fs/kernfs/file.c
View File

@ -965,6 +965,8 @@ const struct file_operations kernfs_file_fops = {
* @parent: directory to create the file in
* @name: name of the file
* @mode: mode of the file
* @uid: uid of the file
* @gid: gid of the file
* @size: size of the file
* @ops: kernfs operations for the file
* @priv: private data for the file
@ -975,7 +977,8 @@ const struct file_operations kernfs_file_fops = {
*/
struct kernfs_node *__kernfs_create_file(struct kernfs_node *parent,
const char *name,
umode_t mode, loff_t size,
umode_t mode, kuid_t uid, kgid_t gid,
loff_t size,
const struct kernfs_ops *ops,
void *priv, const void *ns,
struct lock_class_key *key)
@ -986,7 +989,8 @@ struct kernfs_node *__kernfs_create_file(struct kernfs_node *parent,
flags = KERNFS_FILE;
kn = kernfs_new_node(parent, name, (mode & S_IALLUGO) | S_IFREG, flags);
kn = kernfs_new_node(parent, name, (mode & S_IALLUGO) | S_IFREG,
uid, gid, flags);
if (!kn)
return ERR_PTR(-ENOMEM);

2
fs/kernfs/inode.c
View File

@ -63,7 +63,7 @@ out_unlock:
return ret;
}
static int __kernfs_setattr(struct kernfs_node *kn, const struct iattr *iattr)
int __kernfs_setattr(struct kernfs_node *kn, const struct iattr *iattr)
{
struct kernfs_iattrs *attrs;
struct iattr *iattrs;

2
fs/kernfs/kernfs-internal.h
View File

@ -90,6 +90,7 @@ int kernfs_iop_setattr(struct dentry *dentry, struct iattr *iattr);
int kernfs_iop_getattr(const struct path *path, struct kstat *stat,
u32 request_mask, unsigned int query_flags);
ssize_t kernfs_iop_listxattr(struct dentry *dentry, char *buf, size_t size);
int __kernfs_setattr(struct kernfs_node *kn, const struct iattr *iattr);
/*
* dir.c
@ -104,6 +105,7 @@ void kernfs_put_active(struct kernfs_node *kn);
int kernfs_add_one(struct kernfs_node *kn);
struct kernfs_node *kernfs_new_node(struct kernfs_node *parent,
const char *name, umode_t mode,
kuid_t uid, kgid_t gid,
unsigned flags);
struct kernfs_node *kernfs_find_and_get_node_by_ino(struct kernfs_root *root,
unsigned int ino);

11
fs/kernfs/symlink.c
View File

@ -21,6 +21,7 @@
* @target: target node for the symlink to point to
*
* Returns the created node on success, ERR_PTR() value on error.
* Ownership of the link matches ownership of the target.
*/
struct kernfs_node *kernfs_create_link(struct kernfs_node *parent,
const char *name,
@ -28,8 +29,16 @@ struct kernfs_node *kernfs_create_link(struct kernfs_node *parent,
{
struct kernfs_node *kn;
int error;
kuid_t uid = GLOBAL_ROOT_UID;
kgid_t gid = GLOBAL_ROOT_GID;
kn = kernfs_new_node(parent, name, S_IFLNK|S_IRWXUGO, KERNFS_LINK);
if (target->iattr) {
uid = target->iattr->ia_iattr.ia_uid;
gid = target->iattr->ia_iattr.ia_gid;
}
kn = kernfs_new_node(parent, name, S_IFLNK|S_IRWXUGO, uid, gid,
KERNFS_LINK);
if (!kn)
return ERR_PTR(-ENOMEM);

4
fs/sysfs/dir.c
View File

@ -52,7 +52,9 @@ int sysfs_create_dir_ns(struct kobject *kobj, const void *ns)
return -ENOENT;
kn = kernfs_create_dir_ns(parent, kobject_name(kobj),
S_IRWXU | S_IRUGO | S_IXUGO, kobj, ns);
S_IRWXU | S_IRUGO | S_IXUGO,
GLOBAL_ROOT_UID, GLOBAL_ROOT_GID,
kobj, ns);
if (IS_ERR(kn)) {
if (PTR_ERR(kn) == -EEXIST)
sysfs_warn_dup(parent, kobject_name(kobj));

5
fs/sysfs/file.c
View File

@ -302,8 +302,9 @@ int sysfs_add_file_mode_ns(struct kernfs_node *parent,
if (!attr->ignore_lockdep)
key = attr->key ?: (struct lock_class_key *)&attr->skey;
#endif
kn = __kernfs_create_file(parent, attr->name, mode & 0777, size, ops,
(void *)attr, ns, key);
kn = __kernfs_create_file(parent, attr->name,
mode & 0777, GLOBAL_ROOT_UID, GLOBAL_ROOT_GID,
size, ops, (void *)attr, ns, key);
if (IS_ERR(kn)) {
if (PTR_ERR(kn) == -EEXIST)
sysfs_warn_dup(parent, attr->name);

28
include/linux/kernfs.h
View File

@ -15,6 +15,7 @@
#include <linux/lockdep.h>
#include <linux/rbtree.h>
#include <linux/atomic.h>
#include <linux/uidgid.h>
#include <linux/wait.h>
struct file;
@ -325,12 +326,14 @@ void kernfs_destroy_root(struct kernfs_root *root);
struct kernfs_node *kernfs_create_dir_ns(struct kernfs_node *parent,
const char *name, umode_t mode,
kuid_t uid, kgid_t gid,
void *priv, const void *ns);
struct kernfs_node *kernfs_create_empty_dir(struct kernfs_node *parent,
const char *name);
struct kernfs_node *__kernfs_create_file(struct kernfs_node *parent,
const char *name,
umode_t mode, loff_t size,
const char *name, umode_t mode,
kuid_t uid, kgid_t gid,
loff_t size,
const struct kernfs_ops *ops,
void *priv, const void *ns,
struct lock_class_key *key);
@ -415,12 +418,14 @@ static inline void kernfs_destroy_root(struct kernfs_root *root) { }
static inline struct kernfs_node *
kernfs_create_dir_ns(struct kernfs_node *parent, const char *name,
umode_t mode, void *priv, const void *ns)
umode_t mode, kuid_t uid, kgid_t gid,
void *priv, const void *ns)
{ return ERR_PTR(-ENOSYS); }
static inline struct kernfs_node *
__kernfs_create_file(struct kernfs_node *parent, const char *name,
umode_t mode, loff_t size, const struct kernfs_ops *ops,
umode_t mode, kuid_t uid, kgid_t gid,
loff_t size, const struct kernfs_ops *ops,
void *priv, const void *ns, struct lock_class_key *key)
{ return ERR_PTR(-ENOSYS); }
@ -498,12 +503,15 @@ static inline struct kernfs_node *
kernfs_create_dir(struct kernfs_node *parent, const char *name, umode_t mode,
void *priv)
{
return kernfs_create_dir_ns(parent, name, mode, priv, NULL);
return kernfs_create_dir_ns(parent, name, mode,
GLOBAL_ROOT_UID, GLOBAL_ROOT_GID,
priv, NULL);
}
static inline struct kernfs_node *
kernfs_create_file_ns(struct kernfs_node *parent, const char *name,
umode_t mode, loff_t size, const struct kernfs_ops *ops,
umode_t mode, kuid_t uid, kgid_t gid,
loff_t size, const struct kernfs_ops *ops,
void *priv, const void *ns)
{
struct lock_class_key *key = NULL;
@ -511,15 +519,17 @@ kernfs_create_file_ns(struct kernfs_node *parent, const char *name,
#ifdef CONFIG_DEBUG_LOCK_ALLOC
key = (struct lock_class_key *)&ops->lockdep_key;
#endif
return __kernfs_create_file(parent, name, mode, size, ops, priv, ns,
key);
return __kernfs_create_file(parent, name, mode, uid, gid,
size, ops, priv, ns, key);
}
static inline struct kernfs_node *
kernfs_create_file(struct kernfs_node *parent, const char *name, umode_t mode,
loff_t size, const struct kernfs_ops *ops, void *priv)
{
return kernfs_create_file_ns(parent, name, mode, size, ops, priv, NULL);
return kernfs_create_file_ns(parent, name, mode,
GLOBAL_ROOT_UID, GLOBAL_ROOT_GID,
size, ops, priv, NULL);
}
static inline int kernfs_remove_by_name(struct kernfs_node *parent,

4
kernel/cgroup/cgroup.c
View File

@ -3557,7 +3557,9 @@ static int cgroup_add_file(struct cgroup_subsys_state *css, struct cgroup *cgrp,
key = &cft->lockdep_key;
#endif
kn = __kernfs_create_file(cgrp->kn, cgroup_file_name(cgrp, cft, name),
cgroup_file_mode(cft), 0, cft->kf_ops, cft,
cgroup_file_mode(cft),
GLOBAL_ROOT_UID, GLOBAL_ROOT_GID,
0, cft->kf_ops, cft,
NULL, key);
if (IS_ERR(kn))
return PTR_ERR(kn);