[CRIU] [PATCH v1 05/12] gc: implement unlocking of tcp connections

[Tycho Andersen]

Hi Eugene,

Sorry for the delay, and thanks for looking into this,

On Thu, Jul 28, 2016 at 08:14:41AM +0300, Eugene Batalov wrote:
> The logic is the same as on criu restore.
> 
> First we read ps tree dump to get information about all its
> tcp connections. If ps tree shares net ns with host then
> we simply run iptables to unlock all ps tree tcp connections.
> If ps tree has unshared net ns then we do nothing because we know
> that this net ns is already destroyed with its ps tree and all
> incoming ps tree TCP packets are just dropped (no destination tcp stack
> exists).
> 
> Signed-off-by: Eugene Batalov <eabatalov89 at gmail.com>
> ---
>  criu/cr-gc.c           | 10 ++++++++++
>  criu/include/net.h     |  1 +
>  criu/include/sk-inet.h |  2 +-
>  criu/net.c             | 12 ++++++++++++
>  criu/sk-tcp.c          |  9 ++++++---
>  5 files changed, 30 insertions(+), 4 deletions(-)
> 
> diff --git a/criu/cr-gc.c b/criu/cr-gc.c
> index 2879365..4c8bea9 100644
> --- a/criu/cr-gc.c
> +++ b/criu/cr-gc.c
> @@ -10,6 +10,8 @@
>  #include "cr_options.h"
>  #include "namespaces.h"
>  #include "util.h"
> +#include "sockets.h"
> +#include "net.h"
>  
>  static int gc_validate_opts(void)
>  {
> @@ -80,6 +82,9 @@ static int gc_do(void)
>  	if (gc_link_remaps() < 0)
>  		return -1;
>  
> +	if (gc_network_unlock() < 0)
> +		return -1;
> +
>  	return 0;
>  }
>  
> @@ -122,6 +127,11 @@ int cr_gc(void)
>  		goto exit;
>  	}
>  
> +	if (collect_inet_sockets()) {
> +		ret = -1;
> +		goto exit;
> +	}
> +
>  	if (opts.show)
>  		ret = gc_show();
>  	else
> diff --git a/criu/include/net.h b/criu/include/net.h
> index ede380f..5e6260a 100644
> --- a/criu/include/net.h
> +++ b/criu/include/net.h
> @@ -19,6 +19,7 @@ extern int collect_net_namespaces(bool for_dump);
>  
>  extern int network_lock(void);
>  extern void network_unlock(void);
> +extern int gc_network_unlock(void);
>  
>  extern struct ns_desc net_ns_desc;
>  
> diff --git a/criu/include/sk-inet.h b/criu/include/sk-inet.h
> index 9d2bda6..c82ffd4 100644
> --- a/criu/include/sk-inet.h
> +++ b/criu/include/sk-inet.h
> @@ -65,7 +65,7 @@ static inline void tcp_repair_off(int fd)
>  }
>  
>  extern void tcp_locked_conn_add(struct inet_sk_info *);
> -extern void rst_unlock_tcp_connections(void);
> +extern int rst_unlock_tcp_connections(void);
>  extern void cpt_unlock_tcp_connections(void);
>  
>  extern int dump_one_tcp(int sk, struct inet_sk_desc *sd);
> diff --git a/criu/net.c b/criu/net.c
> index a03c168..ef203a8 100644
> --- a/criu/net.c
> +++ b/criu/net.c
> @@ -1618,6 +1618,18 @@ void network_unlock(void)
>  	}
>  }
>  
> +int gc_network_unlock(void)
> +{
> +	/*
> +	 * Unshared ps tree net ns is destroyed after successful dump.
> +	 * No need to call network_unlock_internal.
> +	 * Also don't call ACT_NET_UNLOCK script because we don't
> +	 * resume/restore ps tree - this call would break
> +	 * ACT_NET_UNLOCK semantics.
> +	 */
> +	return rst_unlock_tcp_connections();

What about cpt_unlock_tcp_connections()? IIUC this list is not
persisted, and so if we leave around the network lock stuff, we would
never turn of TCP repair mode.

Tycho

> +}
> +
>  int veth_pair_add(char *in, char *out)
>  {
>  	char *aux;
> diff --git a/criu/sk-tcp.c b/criu/sk-tcp.c
> index 13d175a..c4aa58f 100644
> --- a/criu/sk-tcp.c
> +++ b/criu/sk-tcp.c
> @@ -713,16 +713,19 @@ void tcp_locked_conn_add(struct inet_sk_info *ii)
>  	ii->sk_fd = -1;
>  }
>  
> -void rst_unlock_tcp_connections(void)
> +int rst_unlock_tcp_connections(void)
>  {
>  	struct inet_sk_info *ii;
>  
>  	/* Network will be unlocked by network-unlock scripts */
>  	if (root_ns_mask & CLONE_NEWNET)
> -		return;
> +		return 0;
>  
>  	list_for_each_entry(ii, &rst_tcp_repair_sockets, rlist)
> -		nf_unlock_connection_info(ii);
> +		if (nf_unlock_connection_info(ii))
> +			return -1;
> +
> +	return 0;
>  }
>  
>  int check_tcp(void)
> -- 
> 1.9.1
> 
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