linux-stable/net/dsa/netlink.c
Vladimir Oltean 56378f3ccb net: dsa: make user ports return to init_net on netns deletion
As pointed out during review, currently the following set of commands
crashes the kernel:

$ ip netns add ns0
$ ip link set swp0 netns ns0
$ ip netns del ns0
WARNING: CPU: 1 PID: 27 at net/core/dev.c:10884 unregister_netdevice_many+0xaa4/0xaec
Workqueue: netns cleanup_net
pstate: 20000005 (nzCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : unregister_netdevice_many+0xaa4/0xaec
lr : unregister_netdevice_many+0x700/0xaec
Call trace:
 unregister_netdevice_many+0xaa4/0xaec
 default_device_exit_batch+0x294/0x340
 ops_exit_list+0xac/0xc4
 cleanup_net+0x2e4/0x544
 process_one_work+0x4ec/0xb40
---[ end trace 0000000000000000 ]---
unregister_netdevice: waiting for swp0 to become free. Usage count = 2

This is because since DSA user ports, since they started populating
dev->rtnl_link_ops in the blamed commit, gained a different treatment
from default_device_exit_net(), which thinks these interfaces can now be
unregistered.

They can't; so set netns_refund = true to restore the behavior prior to
populating dev->rtnl_link_ops.

Fixes: 95f510d0b7 ("net: dsa: allow the DSA master to be seen and changed through rtnetlink")
Suggested-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Link: https://lore.kernel.org/r/20220921185428.1767001-1-vladimir.oltean@nxp.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2022-09-26 11:28:57 -07:00

63 lines
1.3 KiB
C

// SPDX-License-Identifier: GPL-2.0
/* Copyright 2022 NXP
*/
#include <linux/netdevice.h>
#include <net/rtnetlink.h>
#include "dsa_priv.h"
static const struct nla_policy dsa_policy[IFLA_DSA_MAX + 1] = {
[IFLA_DSA_MASTER] = { .type = NLA_U32 },
};
static int dsa_changelink(struct net_device *dev, struct nlattr *tb[],
struct nlattr *data[],
struct netlink_ext_ack *extack)
{
int err;
if (!data)
return 0;
if (data[IFLA_DSA_MASTER]) {
u32 ifindex = nla_get_u32(data[IFLA_DSA_MASTER]);
struct net_device *master;
master = __dev_get_by_index(dev_net(dev), ifindex);
if (!master)
return -EINVAL;
err = dsa_slave_change_master(dev, master, extack);
if (err)
return err;
}
return 0;
}
static size_t dsa_get_size(const struct net_device *dev)
{
return nla_total_size(sizeof(u32)) + /* IFLA_DSA_MASTER */
0;
}
static int dsa_fill_info(struct sk_buff *skb, const struct net_device *dev)
{
struct net_device *master = dsa_slave_to_master(dev);
if (nla_put_u32(skb, IFLA_DSA_MASTER, master->ifindex))
return -EMSGSIZE;
return 0;
}
struct rtnl_link_ops dsa_link_ops __read_mostly = {
.kind = "dsa",
.priv_size = sizeof(struct dsa_port),
.maxtype = IFLA_DSA_MAX,
.policy = dsa_policy,
.changelink = dsa_changelink,
.get_size = dsa_get_size,
.fill_info = dsa_fill_info,
.netns_refund = true,
};