[CRIU] [PATCH v2 2/3] inet: remember ipv6 connections' ifindex for restore

[Tycho Andersen]

On Wed, Nov 25, 2015 at 12:35:21PM +0300, Pavel Emelyanov wrote:
> > @@ -298,6 +301,21 @@ static int do_dump_one_inet_fd(int lfd, u32 id, const struct fd_parms *p, int fa
> >  
> >  		ie.v6only = val ? true : false;
> >  		ie.has_v6only = true;
> > +
> > +		/* ifindex only matters on source ports for bind, so let's
> > +		 * find only that ifindex. */
> > +		if (getsockopt(lfd, SOL_SOCKET, SO_BINDTODEVICE, device, &len) < 0) {
> > +			pr_perror("can't get ifname");
> > +			goto err;
> > +		}
> > +
> > +		if (len > 0) {
> > +			ie.ifname = xstrdup(device);
> > +			if (!ie.ifname)
> > +				goto err;
> > +		} else {
> > +			pr_warn("couldn't find ifname for %d, can't bind\n", id);
> 
> The "no device" is a valid situation actually. Would you (incrementally is OK)
> relax this check to
> 
> 	else if (len == 0)
> 		/* do nothing, it's OK not to have a device */
> 		;
> 
> ?

Right, that's why I just put it as a warning, because it's not
necessarily fatal unless there is something bound to this device.
Anyway, I can send another version (or patch on top if you happen to
apply this before monday).

> > +		}
> >  	}
> >  
> >  	ie.src_addr = xmalloc(pb_repeated_size(&ie, src_addr));
> > @@ -607,7 +625,7 @@ union sockaddr_inet {
> >  };
> >  
> >  static int restore_sockaddr(union sockaddr_inet *sa,
> > -		int family, u32 pb_port, u32 *pb_addr)
> > +		int family, u32 pb_port, u32 *pb_addr, u32 ifindex)
> >  {
> >  	BUILD_BUG_ON(sizeof(sa->v4.sin_addr.s_addr) > PB_ALEN_INET * sizeof(u32));
> >  	BUILD_BUG_ON(sizeof(sa->v6.sin6_addr.s6_addr) > PB_ALEN_INET6 * sizeof(u32));
> > @@ -625,6 +643,12 @@ static int restore_sockaddr(union sockaddr_inet *sa,
> >  		sa->v6.sin6_family = AF_INET6;
> >  		sa->v6.sin6_port = htons(pb_port);
> >  		memcpy(sa->v6.sin6_addr.s6_addr, pb_addr, sizeof(sa->v6.sin6_addr.s6_addr));
> > +
> > +		/* Here although the struct member is called scope_id, the
> > +		 * kernel really wants ifindex. See
> > +		 * /net/ipv6/af_inet6.c:inet6_bind for details.
> 
> The inet6_bind doesn't _always_ require a device, but only for __ipv6_addr_needs_scope_id :)
> Do I get it right that for those cases we will have ie->ifname == NULL at dump?

I think you mean ie->ifname != NULL here? I don't know, but I sure
hope so :). If the device doesn't have an ifname, I don't know how we
can resolve the ifindex to pass to bind() on restore. Since the
original socket creator would have this restriction too, I think it
*should* always work :)

Tycho