nfsd: check passed socket's net matches NFSd superblock's one

commit 3064639423c48d6e0eb9ecc27c512a58e38c6c57 upstream.

There could be a case, when NFSd file system is mounted in network, different
to socket's one, like below:

"ip netns exec" creates new network and mount namespace, which duplicates NFSd
mount point, created in init_net context. And thus NFS server stop in nested
network context leads to RPCBIND client destruction in init_net.
Then, on NFSd start in nested network context, rpc.nfsd process creates socket
in nested net and passes it into "write_ports", which leads to RPCBIND sockets
creation in init_net context because of the same reason (NFSd monut point was
created in init_net context). An attempt to register passed socket in nested
net leads to panic, because no RPCBIND client present in nexted network
namespace.

This patch add check that passed socket's net matches NFSd superblock's one.
And returns -EINVAL error to user psace otherwise.

v2: Put socket on exit.

Reported-by: Weng Meiling <wengmeiling.weng@huawei.com>
Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c
index 7f555179bf81b725364e558f76ba20ccfa2fb4ad..f34d9de802abc7bfea33c14388020abcfcd007dc 100644 (file)
--- 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 to NFSd's one\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 62fd1b756e9914a63ea72ae21a401a7b14115161..947009ed59969af2b79ca3f2a049eaec323f3f3c 100644 (file)
--- 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 305374d4fb985ec4942040447f91e8d8277ea10d..422759bae60d64f42a3bb488bca993d6fca22733 100644 (file)
--- a/net/sunrpc/svcsock.c
+++ b/net/sunrpc/svcsock.c
@@ -1393,6 +1393,22 @@ 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);
+       bool ret = false;
+
+       if (!sock)
+               goto out;
+       if (sock_net(sock->sk) != net)
+               ret = true;
+       sockfd_put(sock);
+out:
+       return ret;
+}
+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