Re: [PATCH net-next v3 5/9] device: add device_change_owner()
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Date: 2020-02-20 11:25:18
Also in:
linux-pm, lkml
On Tue, Feb 18, 2020 at 05:29:39PM +0100, Christian Brauner wrote:
quoted hunk ↗ jump to hunk
Add a helper to change the owner of a device's sysfs entries. This needs to happen when the ownership of a device is changed, e.g. when moving network devices between network namespaces. This function will be used to correctly account for ownership changes, e.g. when moving network devices between network namespaces. Signed-off-by: Christian Brauner <redacted> --- /* v2 */ unchanged /* v3 */ - Greg Kroah-Hartman [off-list ref]: - Add explicit uid/gid parameters. --- drivers/base/core.c | 80 ++++++++++++++++++++++++++++++++++++++++++ include/linux/device.h | 1 + 2 files changed, 81 insertions(+)diff --git a/drivers/base/core.c b/drivers/base/core.c index 42a672456432..ec0d5e8cfd0f 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c@@ -3458,6 +3458,86 @@ int device_move(struct device *dev, struct device *new_parent, } EXPORT_SYMBOL_GPL(device_move); +static int device_attrs_change_owner(struct device *dev, kuid_t kuid, + kgid_t kgid) +{ + struct kobject *kobj = &dev->kobj; + struct class *class = dev->class; + const struct device_type *type = dev->type; + int error; + + if (class) { + error = sysfs_groups_change_owner(kobj, class->dev_groups, kuid, + kgid); + if (error) + return error; + } + + if (type) { + error = sysfs_groups_change_owner(kobj, type->groups, kuid, + kgid); + if (error) + return error; + } + + error = sysfs_groups_change_owner(kobj, dev->groups, kuid, kgid); + if (error) + return error; + + if (device_supports_offline(dev) && !dev->offline_disabled) { + error = sysfs_file_change_owner_by_name( + kobj, dev_attr_online.attr.name, kuid, kgid); + if (error) + return error; + } + + return 0; +} + +/** + * device_change_owner - change the owner of an existing device.
The "owner" and what else gets changed here? Please document this better.
+ * @dev: device.
+ * @kuid: new owner's kuid
+ * @kgid: new owner's kgid
+ */
+int device_change_owner(struct device *dev, kuid_t kuid, kgid_t kgid)
+{
+ int error;
+ struct kobject *kobj = &dev->kobj;
+
+ dev = get_device(dev);
+ if (!dev)
+ return -EINVAL;
+
+ error = sysfs_change_owner(kobj, kuid, kgid);the kobject of the device is changed, good.
+ if (error) + goto out; + + error = sysfs_file_change_owner_by_name(kobj, dev_attr_uevent.attr.name, + kuid, kgid);
Why call out the uevent file explicitly here?
+ if (error) + goto out; + + error = device_attrs_change_owner(dev, kuid, kgid); + if (error) + goto out;
Doesn't this also change the uevent file?
+ +#ifdef CONFIG_BLOCK + if (sysfs_deprecated && dev->class == &block_class) + goto out; +#endif
Ugh, we still need this?
+ + error = sysfs_link_change_owner(&dev->class->p->subsys.kobj, &dev->kobj, + dev_name(dev), kuid, kgid);
Now what is this changing? Again, more documentation please as to exactly what is being changed in this function is needed. thanks, greg k-h