net-sysfs: add netdev_change_owner()
Add a function to change the owner of a network device when it is moved between network namespaces. Currently, when moving network devices between network namespaces the ownership of the corresponding sysfs entries is not changed. This leads to problems when tools try to operate on the corresponding sysfs files. This leads to a bug whereby a network device that is created in a network namespaces owned by a user namespace will have its corresponding sysfs entry owned by the root user of the corresponding user namespace. If such a network device has to be moved back to the host network namespace the permissions will still be set to the user namespaces. This means unprivileged users can e.g. trigger uevents for such incorrectly owned devices. They can also modify the settings of the device itself. Both of these things are unwanted. For example, workloads will create network devices in the host network namespace. Other tools will then proceed to move such devices between network namespaces owner by other user namespaces. While the ownership of the device itself is updated in net/core/net-sysfs.c:dev_change_net_namespace() the corresponding sysfs entry for the device is not: drwxr-xr-x 5 nobody nobody 0 Jan 25 18:08 . drwxr-xr-x 9 nobody nobody 0 Jan 25 18:08 .. -r--r--r-- 1 nobody nobody 4096 Jan 25 18:09 addr_assign_type -r--r--r-- 1 nobody nobody 4096 Jan 25 18:09 addr_len -r--r--r-- 1 nobody nobody 4096 Jan 25 18:09 address -r--r--r-- 1 nobody nobody 4096 Jan 25 18:09 broadcast -rw-r--r-- 1 nobody nobody 4096 Jan 25 18:09 carrier -r--r--r-- 1 nobody nobody 4096 Jan 25 18:09 carrier_changes -r--r--r-- 1 nobody nobody 4096 Jan 25 18:09 carrier_down_count -r--r--r-- 1 nobody nobody 4096 Jan 25 18:09 carrier_up_count -r--r--r-- 1 nobody nobody 4096 Jan 25 18:09 dev_id -r--r--r-- 1 nobody nobody 4096 Jan 25 18:09 dev_port -r--r--r-- 1 nobody nobody 4096 Jan 25 18:09 dormant -r--r--r-- 1 nobody nobody 4096 Jan 25 18:09 duplex -rw-r--r-- 1 nobody nobody 4096 Jan 25 18:09 flags -rw-r--r-- 1 nobody nobody 4096 Jan 25 18:09 gro_flush_timeout -rw-r--r-- 1 nobody nobody 4096 Jan 25 18:09 ifalias -r--r--r-- 1 nobody nobody 4096 Jan 25 18:09 ifindex -r--r--r-- 1 nobody nobody 4096 Jan 25 18:09 iflink -r--r--r-- 1 nobody nobody 4096 Jan 25 18:09 link_mode -rw-r--r-- 1 nobody nobody 4096 Jan 25 18:09 mtu -r--r--r-- 1 nobody nobody 4096 Jan 25 18:09 name_assign_type -rw-r--r-- 1 nobody nobody 4096 Jan 25 18:09 netdev_group -r--r--r-- 1 nobody nobody 4096 Jan 25 18:09 operstate -r--r--r-- 1 nobody nobody 4096 Jan 25 18:09 phys_port_id -r--r--r-- 1 nobody nobody 4096 Jan 25 18:09 phys_port_name -r--r--r-- 1 nobody nobody 4096 Jan 25 18:09 phys_switch_id drwxr-xr-x 2 nobody nobody 0 Jan 25 18:09 power -rw-r--r-- 1 nobody nobody 4096 Jan 25 18:09 proto_down drwxr-xr-x 4 nobody nobody 0 Jan 25 18:09 queues -r--r--r-- 1 nobody nobody 4096 Jan 25 18:09 speed drwxr-xr-x 2 nobody nobody 0 Jan 25 18:09 statistics lrwxrwxrwx 1 nobody nobody 0 Jan 25 18:08 subsystem -> ../../../../class/net -rw-r--r-- 1 nobody nobody 4096 Jan 25 18:09 tx_queue_len -r--r--r-- 1 nobody nobody 4096 Jan 25 18:09 type -rw-r--r-- 1 nobody nobody 4096 Jan 25 18:08 uevent However, if a device is created directly in the network namespace then the device's sysfs permissions will be correctly updated: drwxr-xr-x 5 root root 0 Jan 25 18:12 . drwxr-xr-x 9 nobody nobody 0 Jan 25 18:08 .. -r--r--r-- 1 root root 4096 Jan 25 18:12 addr_assign_type -r--r--r-- 1 root root 4096 Jan 25 18:12 addr_len -r--r--r-- 1 root root 4096 Jan 25 18:12 address -r--r--r-- 1 root root 4096 Jan 25 18:12 broadcast -rw-r--r-- 1 root root 4096 Jan 25 18:12 carrier -r--r--r-- 1 root root 4096 Jan 25 18:12 carrier_changes -r--r--r-- 1 root root 4096 Jan 25 18:12 carrier_down_count -r--r--r-- 1 root root 4096 Jan 25 18:12 carrier_up_count -r--r--r-- 1 root root 4096 Jan 25 18:12 dev_id -r--r--r-- 1 root root 4096 Jan 25 18:12 dev_port -r--r--r-- 1 root root 4096 Jan 25 18:12 dormant -r--r--r-- 1 root root 4096 Jan 25 18:12 duplex -rw-r--r-- 1 root root 4096 Jan 25 18:12 flags -rw-r--r-- 1 root root 4096 Jan 25 18:12 gro_flush_timeout -rw-r--r-- 1 root root 4096 Jan 25 18:12 ifalias -r--r--r-- 1 root root 4096 Jan 25 18:12 ifindex -r--r--r-- 1 root root 4096 Jan 25 18:12 iflink -r--r--r-- 1 root root 4096 Jan 25 18:12 link_mode -rw-r--r-- 1 root root 4096 Jan 25 18:12 mtu -r--r--r-- 1 root root 4096 Jan 25 18:12 name_assign_type -rw-r--r-- 1 root root 4096 Jan 25 18:12 netdev_group -r--r--r-- 1 root root 4096 Jan 25 18:12 operstate -r--r--r-- 1 root root 4096 Jan 25 18:12 phys_port_id -r--r--r-- 1 root root 4096 Jan 25 18:12 phys_port_name -r--r--r-- 1 root root 4096 Jan 25 18:12 phys_switch_id drwxr-xr-x 2 root root 0 Jan 25 18:12 power -rw-r--r-- 1 root root 4096 Jan 25 18:12 proto_down drwxr-xr-x 4 root root 0 Jan 25 18:12 queues -r--r--r-- 1 root root 4096 Jan 25 18:12 speed drwxr-xr-x 2 root root 0 Jan 25 18:12 statistics lrwxrwxrwx 1 nobody nobody 0 Jan 25 18:12 subsystem -> ../../../../class/net -rw-r--r-- 1 root root 4096 Jan 25 18:12 tx_queue_len -r--r--r-- 1 root root 4096 Jan 25 18:12 type -rw-r--r-- 1 root root 4096 Jan 25 18:12 uevent Now, when creating a network device in a network namespace owned by a user namespace and moving it to the host the permissions will be set to the id that the user namespace root user has been mapped to on the host leading to all sorts of permission issues: 458752 drwxr-xr-x 5 458752 458752 0 Jan 25 18:12 . drwxr-xr-x 9 root root 0 Jan 25 18:08 .. -r--r--r-- 1 458752 458752 4096 Jan 25 18:12 addr_assign_type -r--r--r-- 1 458752 458752 4096 Jan 25 18:12 addr_len -r--r--r-- 1 458752 458752 4096 Jan 25 18:12 address -r--r--r-- 1 458752 458752 4096 Jan 25 18:12 broadcast -rw-r--r-- 1 458752 458752 4096 Jan 25 18:12 carrier -r--r--r-- 1 458752 458752 4096 Jan 25 18:12 carrier_changes -r--r--r-- 1 458752 458752 4096 Jan 25 18:12 carrier_down_count -r--r--r-- 1 458752 458752 4096 Jan 25 18:12 carrier_up_count -r--r--r-- 1 458752 458752 4096 Jan 25 18:12 dev_id -r--r--r-- 1 458752 458752 4096 Jan 25 18:12 dev_port -r--r--r-- 1 458752 458752 4096 Jan 25 18:12 dormant -r--r--r-- 1 458752 458752 4096 Jan 25 18:12 duplex -rw-r--r-- 1 458752 458752 4096 Jan 25 18:12 flags -rw-r--r-- 1 458752 458752 4096 Jan 25 18:12 gro_flush_timeout -rw-r--r-- 1 458752 458752 4096 Jan 25 18:12 ifalias -r--r--r-- 1 458752 458752 4096 Jan 25 18:12 ifindex -r--r--r-- 1 458752 458752 4096 Jan 25 18:12 iflink -r--r--r-- 1 458752 458752 4096 Jan 25 18:12 link_mode -rw-r--r-- 1 458752 458752 4096 Jan 25 18:12 mtu -r--r--r-- 1 458752 458752 4096 Jan 25 18:12 name_assign_type -rw-r--r-- 1 458752 458752 4096 Jan 25 18:12 netdev_group -r--r--r-- 1 458752 458752 4096 Jan 25 18:12 operstate -r--r--r-- 1 458752 458752 4096 Jan 25 18:12 phys_port_id -r--r--r-- 1 458752 458752 4096 Jan 25 18:12 phys_port_name -r--r--r-- 1 458752 458752 4096 Jan 25 18:12 phys_switch_id drwxr-xr-x 2 458752 458752 0 Jan 25 18:12 power -rw-r--r-- 1 458752 458752 4096 Jan 25 18:12 proto_down drwxr-xr-x 4 458752 458752 0 Jan 25 18:12 queues -r--r--r-- 1 458752 458752 4096 Jan 25 18:12 speed drwxr-xr-x 2 458752 458752 0 Jan 25 18:12 statistics lrwxrwxrwx 1 root root 0 Jan 25 18:12 subsystem -> ../../../../class/net -rw-r--r-- 1 458752 458752 4096 Jan 25 18:12 tx_queue_len -r--r--r-- 1 458752 458752 4096 Jan 25 18:12 type -rw-r--r-- 1 458752 458752 4096 Jan 25 18:12 uevent Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com> Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Christian Brauner
David S. Miller
parent
3b52fc5d78
commit
e6dee9f389
@ -1767,6 +1767,33 @@ int netdev_register_kobject(struct net_device *ndev)
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return error;
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}
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/* Change owner for sysfs entries when moving network devices across network
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* namespaces owned by different user namespaces.
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*/
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int netdev_change_owner(struct net_device *ndev, const struct net *net_old,
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const struct net *net_new)
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{
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struct device *dev = &ndev->dev;
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kuid_t old_uid, new_uid;
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kgid_t old_gid, new_gid;
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int error;
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net_ns_get_ownership(net_old, &old_uid, &old_gid);
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net_ns_get_ownership(net_new, &new_uid, &new_gid);
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/* The network namespace was changed but the owning user namespace is
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* identical so there's no need to change the owner of sysfs entries.
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*/
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if (uid_eq(old_uid, new_uid) && gid_eq(old_gid, new_gid))
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return 0;
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error = device_change_owner(dev, new_uid, new_gid);
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if (error)
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return error;
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return 0;
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}
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int netdev_class_create_file_ns(const struct class_attribute *class_attr,
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const void *ns)
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{
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@ -8,5 +8,7 @@ void netdev_unregister_kobject(struct net_device *);
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int net_rx_queue_update_kobjects(struct net_device *, int old_num, int new_num);
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int netdev_queue_update_kobjects(struct net_device *net,
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int old_num, int new_num);
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int netdev_change_owner(struct net_device *, const struct net *net_old,
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const struct net *net_new);
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#endif
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