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

["Denis V. Lunev" <den-GEFAQzZX7r8dnm+yROfE0A@public.gmane.org>]

On Wed, 2008-10-01 at 13:55 +0200, Daniel Lezcano wrote:
> Denis V. Lunev wrote:
> > On Wed, 2008-10-01 at 13:13 +0200, Daniel Lezcano wrote:
> >> 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-GEFAQzZX7r8dnm+yROfE0A@public.gmane.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).
> > 
> > we have asked from our customers for a shared MySQL server
> > 
> > The full story is here :)
> > http://bugzilla.openvz.org/show_bug.cgi?id=985
> 
> Ok, thanks.
> 
> My question remains :)
> 
> How do you handle migration in this case ?

There is no problem until you really have listeners from different
namespaces on both ends. This is checked after the freeze stage and
migration is forbidden if such a situation is detected.