Re: [PATCH] nfsd: check passed socket's net matches NFSd superblock's one

[Stanislav Kinsbursky <skinsbursky@parallels.com>]

19.02.2014 18:50, J. Bruce Fields пишет:
> On Wed, Feb 19, 2014 at 02:26:33PM +0400, Stanislav Kinsbursky wrote:
>> 18.02.2014 19:44, J. Bruce Fields пишет:
>>> On Tue, Feb 18, 2014 at 07:19:31PM +0400, Stanislav Kinsbursky wrote:
>>>> 18.02.2014 02:19, J. Bruce Fields пишет:
>>>>> On Sat, Feb 15, 2014 at 09:51:20AM +0800, Weng Meiling wrote:
>>>>>> Hi Bruce,
>>>>>>
>>>>>> The upstream has merged your git tree for-3.14, but there is no this patch?
>>>>>> Do you forget this patch?
>>>>>
>>>>> Apologies, I'm not sure what happened.
>>>>>
>>>>> Looking back at it....  The patch causes all my pynfs reboot recovery
>>>>> tests to fail.  They're just doing a "systemctl restart
>>>>> nfs-server.service", and "systemctl status nfs-server.service" shows in
>>>>> part
>>>>>
>>>>> 	ExecStart=/usr/sbin/rpc.nfsd $RPCNFSDARGS $RPCNFSDCOUNT (code=exited, status=1/FAILURE)
>>>>>
>>>>> So the patch is causing rpc.nfsd to fail?  No network namespaces should
>>>>> be involved.
>>>>>
>>>>> I haven't investigated any further.
>>>>>
>>>>
>>>> Hi Bruce,
>>>> Are you sure, that exactly this patch broke your pynfs tests?
>>>> BTW, systemd manipulates namespaces. Maybe the patch revealed some pynfs internal bugs?
>>>> What do you think?
>>>
>>> It's really just "systemctl restart nfs-server.service" that the patch
>>> breaks, pynfs isn't involved much.
>>>
>>> The patch I'm actually using follows, but I believe the only difference
>>> is in the printk message?
>>>
>>
>> Yep, looks true.
>> That's strange: "systemctl restart nfs-server.service" works for me on Fedora 18 with kernel, based on your repo.
>
> OK, I'll take a closer look and let you know what I find.
>

Thank you, Bruce!

> --b.
>
>>
>>> --b
>>>
>>> commit e1f2922c12cb59baba0f2c7726bee992a0861310
>>> Author: Stanislav Kinsbursky <skinsbursky@parallels.com>
>>> Date:   Mon Dec 30 17:23:59 2013 +0300
>>>
>>>      nfsd: check passed socket's net matches the NFSd superblock's
>>>
>>>      The file descriptor written to the nfsd/portlist file could be for a
>>>      socket in a different network namespace from the network namespace that
>>>      the nfsd filesystem was mounted in, and this can cause a crash.
>>>
>>>      For example: "ip netns exec" creates a new network and mount namespace,
>>>      which duplicates the nfsd mount point which was created in the init_net
>>>      context.  Thus NFS server stop in the nested network context leads to
>>>      RPCBIND client destruction in init_net.  Then, on nfsd start in the
>>>      nested network context, the rpc.nfsd process creates a socket in the
>>>      nested net and passes it into "write_ports", which leads to RPCBIND
>>>      socket creation in init_net context for the same reason (the nfsd mount
>>>      point was created in the init_net context). An attempt to register
>>>      passed socket in nested net leads to panic, because no RPCBIND client is
>>>      present in the nested network namespace.
>>>
>>>      This patch adds a check that the passed the socket's net matches the
>>>      nfsd superblock's net, and returns -EINVAL error to user space if not.
>>>
>>>      Reported-by: Weng Meiling <wengmeiling.weng@huawei.com>
>>>      Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com>
>>>      Cc: stable@vger.kernel.org
>>>      Signed-off-by: J. Bruce Fields <bfields@redhat.com>
>>>
>>> diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c
>>> index 7f55517..1331766 100644
>>> --- a/fs/nfsd/nfsctl.c
>>> +++ b/fs/nfsd/nfsctl.c
>>> @@ -699,6 +699,11 @@ static ssize_t __write_ports_addfd(char *buf, struct net *net)
>>>   	if (err != 0 || fd < 0)
>>>   		return -EINVAL;
>>>
>>> +	if (svc_alien_sock(net, fd)) {
>>> +		printk(KERN_ERR "%s: socket net is different from NFSd's\n", __func__);
>>> +		return -EINVAL;
>>> +	}
>>> +
>>>   	err = nfsd_create_serv(net);
>>>   	if (err != 0)
>>>   		return err;
>>> diff --git a/include/linux/sunrpc/svcsock.h b/include/linux/sunrpc/svcsock.h
>>> index 62fd1b7..947009e 100644
>>> --- a/include/linux/sunrpc/svcsock.h
>>> +++ b/include/linux/sunrpc/svcsock.h
>>> @@ -56,6 +56,7 @@ int		svc_recv(struct svc_rqst *, long);
>>>   int		svc_send(struct svc_rqst *);
>>>   void		svc_drop(struct svc_rqst *);
>>>   void		svc_sock_update_bufs(struct svc_serv *serv);
>>> +bool		svc_alien_sock(struct net *net, int fd);
>>>   int		svc_addsock(struct svc_serv *serv, const int fd,
>>>   					char *name_return, const size_t len);
>>>   void		svc_init_xprt_sock(void);
>>> diff --git a/net/sunrpc/svcsock.c b/net/sunrpc/svcsock.c
>>> index b6e59f0..3ba5b87 100644
>>> --- a/net/sunrpc/svcsock.c
>>> +++ b/net/sunrpc/svcsock.c
>>> @@ -1397,6 +1397,17 @@ static struct svc_sock *svc_setup_socket(struct svc_serv *serv,
>>>   	return svsk;
>>>   }
>>>
>>> +bool svc_alien_sock(struct net *net, int fd)
>>> +{
>>> +	int err;
>>> +	struct socket *sock = sockfd_lookup(fd, &err);
>>> +
>>> +	if (sock && (sock_net(sock->sk) != net))
>>> +		return true;
>>> +	return false;
>>> +}
>>> +EXPORT_SYMBOL_GPL(svc_alien_sock);
>>> +
>>>   /**
>>>    * svc_addsock - add a listener socket to an RPC service
>>>    * @serv: pointer to RPC service to which to add a new listener
>>>
>>
>>
>> --
>> Best regards,
>> Stanislav Kinsbursky


-- 
Best regards,
Stanislav Kinsbursky