netdev - Re: [PATCH 4 net] RDMA/core: fix UAF with ib_device_get

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Message-ID: <e5eac29d-a9d3-4f03-86bc-64013be2cc39@suse.de>
Date: Tue, 2 Apr 2024 16:05:58 +0300
From: Denis Kirjanov <dkirjanov@...e.de>
To: Ratheesh Kannoth <rkannoth@...vell.com>,
 Denis Kirjanov <kirjanov@...il.com>
Cc: netdev@...r.kernel.org, edumazet@...gle.com, jgg@...pe.ca,
 leon@...nel.org, syzbot+5fe14f2ff4ccbace9a26@...kaller.appspotmail.com
Subject: Re: [PATCH 4 net] RDMA/core: fix UAF with ib_device_get_netdev()



On 4/1/24 16:35, Ratheesh Kannoth wrote:
> On 2024-04-01 at 15:30:05, Denis Kirjanov (kirjanov@...il.com) wrote:
>> A call to ib_device_get_netdev may lead to a race condition
>> while accessing a netdevice instance since we don't hold
>> the rtnl lock while checking
>> the registration state:
>> 	if (res && res->reg_state != NETREG_REGISTERED) {
>>
>> v2: unlock rtnl on error path
>> v3: update remaining callers of ib_device_get_netdev
>> v4: don't call a cb with rtnl lock in ib_enum_roce_netdev
>>
>> Reported-by: syzbot+5fe14f2ff4ccbace9a26@...kaller.appspotmail.com
>> Fixes: d41861942fc55 ("IB/core: Add generic function to extract IB speed from netdev")
>> Signed-off-by: Denis Kirjanov <dkirjanov@...e.de>
>> ---
>>  drivers/infiniband/core/cache.c  |  2 ++
>>  drivers/infiniband/core/device.c | 15 ++++++++++++---
>>  drivers/infiniband/core/nldev.c  |  3 +++
>>  drivers/infiniband/core/verbs.c  |  6 ++++--
>>  4 files changed, 21 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/infiniband/core/cache.c b/drivers/infiniband/core/cache.c
>> index c02a96d3572a..cf9c826cd520 100644
>> --- a/drivers/infiniband/core/cache.c
>> +++ b/drivers/infiniband/core/cache.c
>> @@ -1461,7 +1461,9 @@ static int config_non_roce_gid_cache(struct ib_device *device,
>>  		if (rdma_protocol_iwarp(device, port)) {
>>  			struct net_device *ndev;
>>
>> +			rtnl_lock();
>>  			ndev = ib_device_get_netdev(device, port);
>> +			rtnl_unlock();
> Why dont you move the rtnl_lock()/_unlock() inside ib_device_get_netdev().
> ib_device_get_netdev() hold ref to dev, so can access ndev safely here.

Makes sense. and it makes the whole change pretty small
> 
>>  			if (!ndev)
>>  				continue;
>>  			RCU_INIT_POINTER(gid_attr.ndev, ndev);
>> diff --git a/drivers/infiniband/core/device.c b/drivers/infiniband/core/device.c
>> index 07cb6c5ffda0..25edb50d2b64 100644
>> --- a/drivers/infiniband/core/device.c
>> +++ b/drivers/infiniband/core/device.c
>> @@ -2026,9 +2026,12 @@ static int iw_query_port(struct ib_device *device,
>>
>>  	memset(port_attr, 0, sizeof(*port_attr));
>>
>> +	rtnl_lock();
>>  	netdev = ib_device_get_netdev(device, port_num);
>> -	if (!netdev)
>> +	if (!netdev) {
>> +		rtnl_unlock();
>>  		return -ENODEV;
>> +	}
>>
>>  	port_attr->max_mtu = IB_MTU_4096;
>>  	port_attr->active_mtu = ib_mtu_int_to_enum(netdev->mtu);
>> @@ -2052,6 +2055,7 @@ static int iw_query_port(struct ib_device *device,
>>  		rcu_read_unlock();
>>  	}
>>
>> +	rtnl_unlock();
>>  	dev_put(netdev);
>>  	return device->ops.query_port(device, port_num, port_attr);
>>  }
>> @@ -2220,6 +2224,8 @@ struct net_device *ib_device_get_netdev(struct ib_device *ib_dev,
>>  	struct ib_port_data *pdata;
>>  	struct net_device *res;
>>
>> +	ASSERT_RTNL();
>> +
>>  	if (!rdma_is_port_valid(ib_dev, port))
>>  		return NULL;
>>
>> @@ -2306,8 +2312,11 @@ void ib_enum_roce_netdev(struct ib_device *ib_dev,
>>
>>  	rdma_for_each_port (ib_dev, port)
>>  		if (rdma_protocol_roce(ib_dev, port)) {
>> -			struct net_device *idev =
>> -				ib_device_get_netdev(ib_dev, port);
>> +			struct net_device *idev;
>> +
>> +			rtnl_lock();
>> +			idev = ib_device_get_netdev(ib_dev, port);
>> +			rtnl_unlock();
>>
>>  			if (filter(ib_dev, port, idev, filter_cookie))
>>  				cb(ib_dev, port, idev, cookie);
>> diff --git a/drivers/infiniband/core/nldev.c b/drivers/infiniband/core/nldev.c
>> index 4900a0848124..5cf7cdae8925 100644
>> --- a/drivers/infiniband/core/nldev.c
>> +++ b/drivers/infiniband/core/nldev.c
>> @@ -360,7 +360,9 @@ static int fill_port_info(struct sk_buff *msg,
>>  	if (nla_put_u8(msg, RDMA_NLDEV_ATTR_PORT_PHYS_STATE, attr.phys_state))
>>  		return -EMSGSIZE;
>>
>> +	rtnl_lock();
>>  	netdev = ib_device_get_netdev(device, port);
>> +
>>  	if (netdev && net_eq(dev_net(netdev), net)) {
>>  		ret = nla_put_u32(msg,
>>  				  RDMA_NLDEV_ATTR_NDEV_INDEX, netdev->ifindex);
>> @@ -371,6 +373,7 @@ static int fill_port_info(struct sk_buff *msg,
>>  	}
>>
>>  out:
>> +	rtnl_unlock();
>>  	dev_put(netdev);
>>  	return ret;
>>  }
>> diff --git a/drivers/infiniband/core/verbs.c b/drivers/infiniband/core/verbs.c
>> index 94a7f3b0c71c..6a3757b00c93 100644
>> --- a/drivers/infiniband/core/verbs.c
>> +++ b/drivers/infiniband/core/verbs.c
>> @@ -1976,11 +1976,13 @@ int ib_get_eth_speed(struct ib_device *dev, u32 port_num, u16 *speed, u8 *width)
>>  	if (rdma_port_get_link_layer(dev, port_num) != IB_LINK_LAYER_ETHERNET)
>>  		return -EINVAL;
>>
>> +	rtnl_lock();
>>  	netdev = ib_device_get_netdev(dev, port_num);
>> -	if (!netdev)
>> +	if (!netdev) {
>> +		rtnl_unlock();
>>  		return -ENODEV;
>> +	}
>>
>> -	rtnl_lock();
>>  	rc = __ethtool_get_link_ksettings(netdev, &lksettings);
>>  	rtnl_unlock();
>>
>> --
>> 2.30.2
>>