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

["J. Bruce Fields" <bfields@fieldses.org>]

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.

--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