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authorChristian Brauner <christian.brauner@ubuntu.com>2020-02-27 04:37:11 +0100
committerDavid S. Miller <davem@davemloft.net>2020-02-27 05:07:25 +0100
commitf70ce185687bbe4e2d7ff126a8c890631f5fc2af (patch)
treefa62764ac154c9e86c2fa446aa534eebefeedb32 /fs/sysfs
parentnet: cisco: Replace zero-length array with flexible-array member (diff)
downloadlinux-f70ce185687bbe4e2d7ff126a8c890631f5fc2af.tar.xz
linux-f70ce185687bbe4e2d7ff126a8c890631f5fc2af.zip
sysfs: add sysfs_file_change_owner()
Add helpers to change the owner of a sysfs files. This function will be used to correctly account for kobject ownership changes, e.g. when moving network devices between network namespaces. Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'fs/sysfs')
-rw-r--r--fs/sysfs/file.c47
1 files changed, 47 insertions, 0 deletions
diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index 130fc6fbcc03..4ca936ca3ba4 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -558,3 +558,50 @@ void sysfs_remove_bin_file(struct kobject *kobj,
kernfs_remove_by_name(kobj->sd, attr->attr.name);
}
EXPORT_SYMBOL_GPL(sysfs_remove_bin_file);
+
+static int internal_change_owner(struct kernfs_node *kn, kuid_t kuid,
+ kgid_t kgid)
+{
+ struct iattr newattrs = {
+ .ia_valid = ATTR_UID | ATTR_GID,
+ .ia_uid = kuid,
+ .ia_gid = kgid,
+ };
+ return kernfs_setattr(kn, &newattrs);
+}
+
+/**
+ * sysfs_file_change_owner - change owner of a sysfs file.
+ * @kobj: object.
+ * @name: name of the file to change.
+ * @kuid: new owner's kuid
+ * @kgid: new owner's kgid
+ *
+ * This function looks up the sysfs entry @name under @kobj and changes the
+ * ownership to @kuid/@kgid.
+ *
+ * Returns 0 on success or error code on failure.
+ */
+int sysfs_file_change_owner(struct kobject *kobj, const char *name, kuid_t kuid,
+ kgid_t kgid)
+{
+ struct kernfs_node *kn;
+ int error;
+
+ if (!name)
+ return -EINVAL;
+
+ if (!kobj->state_in_sysfs)
+ return -EINVAL;
+
+ kn = kernfs_find_and_get(kobj->sd, name);
+ if (!kn)
+ return -ENOENT;
+
+ error = internal_change_owner(kn, kuid, kgid);
+
+ kernfs_put(kn);
+
+ return error;
+}
+EXPORT_SYMBOL_GPL(sysfs_file_change_owner);