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net: create reusable function for getting ownership info of sysfs inodes

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Make net_ns_get_ownership() reusable by networking code outside of core.
This is useful, for example, to allow bridge related sysfs files to be
owned by container root.

Add a function comment since this is a potentially dangerous function to
use given the way that kobject_get_ownership() works by initializing uid
and gid before calling .get_ownership().

Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Tyler Hicks 2018-07-20 21:56:53 +00:00 committed by David S. Miller
parent b0e37c0d8a
commit fbdeaed408
3 changed files with 38 additions and 18 deletions
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10
include/net/net_namespace.h
View File

@ -10,6 +10,7 @@
#include <linux/workqueue.h>
#include <linux/list.h>
#include <linux/sysctl.h>
#include <linux/uidgid.h>
#include <net/flow.h>
#include <net/netns/core.h>
@ -170,6 +171,8 @@ extern struct net init_net;
struct net *copy_net_ns(unsigned long flags, struct user_namespace *user_ns,
struct net *old_net);
void net_ns_get_ownership(const struct net *net, kuid_t *uid, kgid_t *gid);
void net_ns_barrier(void);
#else /* CONFIG_NET_NS */
#include <linux/sched.h>
@ -182,6 +185,13 @@ static inline struct net *copy_net_ns(unsigned long flags,
return old_net;
}
static inline void net_ns_get_ownership(const struct net *net,
kuid_t *uid, kgid_t *gid)
{
*uid = GLOBAL_ROOT_UID;
*gid = GLOBAL_ROOT_GID;
}
static inline void net_ns_barrier(void) {}
#endif /* CONFIG_NET_NS */

18
net/core/net-sysfs.c
View File

@ -656,24 +656,6 @@ static const struct attribute_group wireless_group = {
#define net_class_groups NULL
#endif /* CONFIG_SYSFS */
static void net_ns_get_ownership(const struct net *net,
kuid_t *uid, kgid_t *gid)
{
if (net) {
kuid_t ns_root_uid = make_kuid(net->user_ns, 0);
kgid_t ns_root_gid = make_kgid(net->user_ns, 0);
if (uid_valid(ns_root_uid))
*uid = ns_root_uid;
if (gid_valid(ns_root_gid))
*gid = ns_root_gid;
} else {
*uid = GLOBAL_ROOT_UID;
*gid = GLOBAL_ROOT_GID;
}
}
#ifdef CONFIG_SYSFS
#define to_rx_queue_attr(_attr) \
container_of(_attr, struct rx_queue_attribute, attr)

28
net/core/net_namespace.c
View File

@ -17,6 +17,7 @@
#include <linux/user_namespace.h>
#include <linux/net_namespace.h>
#include <linux/sched/task.h>
#include <linux/uidgid.h>
#include <net/sock.h>
#include <net/netlink.h>
@ -448,6 +449,33 @@ dec_ucounts:
return net;
}
/**
* net_ns_get_ownership - get sysfs ownership data for @net
* @net: network namespace in question (can be NULL)
* @uid: kernel user ID for sysfs objects
* @gid: kernel group ID for sysfs objects
*
* Returns the uid/gid pair of root in the user namespace associated with the
* given network namespace.
*/
void net_ns_get_ownership(const struct net *net, kuid_t *uid, kgid_t *gid)
{
if (net) {
kuid_t ns_root_uid = make_kuid(net->user_ns, 0);
kgid_t ns_root_gid = make_kgid(net->user_ns, 0);
if (uid_valid(ns_root_uid))
*uid = ns_root_uid;
if (gid_valid(ns_root_gid))
*gid = ns_root_gid;
} else {
*uid = GLOBAL_ROOT_UID;
*gid = GLOBAL_ROOT_GID;
}
}
EXPORT_SYMBOL_GPL(net_ns_get_ownership);
static void unhash_nsid(struct net *net, struct net *last)
{
struct net *tmp;