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

[Pavel Emelyanov]

> @@ -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 */
		;

?

> +		}
>  	}
>  
>  	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?

> +		 */
> +		sa->v6.sin6_scope_id = ifindex;
>  		return sizeof(sa->v6);
>  	}
>