Re: [PATCH net-next] [RFC] netns: enable cross-ve Unix sockets

[Daniel Lezcano <dlezcano@fr.ibm.com>]

Denis V. Lunev wrote:
> This patch opens a way to connect via Unix socket from one namespace
> to another if these sockets are opened via conventional filesystem
> interface. Such approach allows to share important services between
> namespaces in efficient way.
> 
> This breach is controlled by the means of shared filesystem, i.e. if
> somebody really wants to isolate containers, he should start from
> filesystem separation.
> 
> Signed-off-by: Denis V. Lunev <den@openvz.org>
> ---
>  net/unix/af_unix.c |    3 ---
>  1 files changed, 0 insertions(+), 3 deletions(-)
> 
> diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
> index 39d2173..0e1eccd 100644
> --- a/net/unix/af_unix.c
> +++ b/net/unix/af_unix.c
> @@ -297,9 +297,6 @@ static struct sock *unix_find_socket_byinode(struct net *net, struct inode *i)
>  		    &unix_socket_table[i->i_ino & (UNIX_HASH_SIZE - 1)]) {
>  		struct dentry *dentry = unix_sk(s)->dentry;
> 
> -		if (!net_eq(sock_net(s), net))
> -			continue;
> -
>  		if(dentry && dentry->d_inode == i)
>  		{
>  			sock_hold(s);

Hi Denis,

Do you have a list of the important services this isolation forbids ? (I 
suppose there is syslog).

Without this isolation, we can not ensure the container will not connect 
to an application outside of the namespace. How can we handle this case 
for the checkpoint-restart/migration ?