[PATCH 1/5] kernfs: allow creating kernfs objects with arbitrary uid/gid
From: Dmitry Torokhov
Date: Tue Aug 16 2016 - 18:35:26 EST
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.
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>
---
fs/kernfs/dir.c | 29 ++++++++++++++++++++++++++---
fs/kernfs/file.c | 8 ++++++--
fs/kernfs/inode.c | 2 +-
fs/kernfs/kernfs-internal.h | 2 ++
fs/kernfs/symlink.c | 11 ++++++++++-
fs/sysfs/dir.c | 4 +++-
fs/sysfs/file.c | 5 +++--
include/linux/kernfs.h | 28 +++++++++++++++++++---------
kernel/cgroup.c | 4 +++-
9 files changed, 73 insertions(+), 20 deletions(-)
diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index 8a65240..67c276a 100644
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -657,6 +657,7 @@ 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;
@@ -683,8 +684,22 @@ 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:
+ ida_simple_remove(&root->ino_ida, kn->ino);
err_out2:
kmem_cache_free(kernfs_node_cache, kn);
err_out1:
@@ -694,11 +709,13 @@ 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;
@@ -919,6 +936,7 @@ struct kernfs_root *kernfs_create_root(struct kernfs_syscall_ops *scops,
INIT_LIST_HEAD(&root->supers);
kn = __kernfs_new_node(root, "", S_IFDIR | S_IRUGO | S_IXUGO,
+ GLOBAL_ROOT_UID, GLOBAL_ROOT_GID,
KERNFS_DIR);
if (!kn) {
ida_destroy(&root->ino_ida);
@@ -957,6 +975,8 @@ 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
*
@@ -964,13 +984,15 @@ 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);
@@ -1001,7 +1023,8 @@ 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);
diff --git a/fs/kernfs/file.c b/fs/kernfs/file.c
index e157400..736a168 100644
--- a/fs/kernfs/file.c
+++ b/fs/kernfs/file.c
@@ -904,6 +904,8 @@ 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
@@ -914,7 +916,8 @@ 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)
@@ -925,7 +928,8 @@ 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);
diff --git a/fs/kernfs/inode.c b/fs/kernfs/inode.c
index 63b925d..3d3f152 100644
--- a/fs/kernfs/inode.c
+++ b/fs/kernfs/inode.c
@@ -66,7 +66,7 @@ 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;
diff --git a/fs/kernfs/kernfs-internal.h b/fs/kernfs/kernfs-internal.h
index 3715923..80f4b5a 100644
--- a/fs/kernfs/kernfs-internal.h
+++ b/fs/kernfs/kernfs-internal.h
@@ -88,6 +88,7 @@ int kernfs_iop_removexattr(struct dentry *dentry, const char *name);
ssize_t kernfs_iop_getxattr(struct dentry *dentry, struct inode *inode,
const char *name, void *buf, size_t size);
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
@@ -102,6 +103,7 @@ 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);
/*
diff --git a/fs/kernfs/symlink.c b/fs/kernfs/symlink.c
index 117b8b3..e0847ce 100644
--- a/fs/kernfs/symlink.c
+++ b/fs/kernfs/symlink.c
@@ -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);
diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index 94374e4..d6a2b76 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -53,7 +53,9 @@ 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));
diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index f35523d..0241830 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -296,8 +296,9 @@ 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);
diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index 96356ef..0a3687d 100644
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -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;
@@ -295,12 +296,14 @@ 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);
@@ -385,12 +388,14 @@ 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); }
@@ -452,12 +457,15 @@ 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;
@@ -465,15 +473,17 @@ 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,
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 75c0ff0..86ec412 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -3634,7 +3634,9 @@ 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);
--
2.8.0.rc3.226.g39d4020