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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
Download Patch File Download Diff File Expand all files Collapse all files

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);