[CRIU] [PATCH 06/10] net: create a parasite socket for each network namespace

[Andrei Vagin]

On Mon, Oct 17, 2016 at 02:45:42PM +0300, Pavel Emelyanov wrote:
> On 09/01/2016 01:55 AM, Andrei Vagin wrote:
> > From: Andrei Vagin <avagin at virtuozzo.com>
> 
> Create? It's already created as such. Should the subject rather be
> 'move parasite socket binding and listening to another place'?

"create" means to create a socket which is ready to accept a
connection;).

The main thing is in "static int ssock = -1;", this means that only one
socket will be "created".
> 
> > CRIU uses an unix socket to comunicate with a parasite code,
> > but an unix socket created from one netns is invisible
> > from another netns.
> > 
> > Signed-off-by: Andrei Vagin <avagin at virtuozzo.com>
> > ---
> >  criu/include/parasite.h |  2 ++
> >  criu/net.c              | 27 +++++++++++++++++++++------
> >  criu/parasite-syscall.c | 22 +++-------------------
> >  3 files changed, 26 insertions(+), 25 deletions(-)
> > 
> > diff --git a/criu/include/parasite.h b/criu/include/parasite.h
> > index 7211477..e26b7f0 100644
> > --- a/criu/include/parasite.h
> > +++ b/criu/include/parasite.h
> > @@ -275,6 +275,8 @@ struct parasite_dump_cgroup_args {
> >  #define parasite_sym(pblob, ptype, symbol)				\
> >  	((void *)(pblob) + __pblob_offset(ptype, symbol))
> >  
> > +extern int gen_parasite_saddr(struct sockaddr_un *saddr, int key);
> > +
> >  #endif /* !__ASSEMBLY__ */
> >  
> >  #include "parasite-compat.h"
> > diff --git a/criu/net.c b/criu/net.c
> > index e4a7627..7a50640 100644
> > --- a/criu/net.c
> > +++ b/criu/net.c
> > @@ -29,6 +29,7 @@
> >  #include "string.h"
> >  #include "sysctl.h"
> >  #include "kerndat.h"
> > +#include "parasite.h"
> >  
> >  #include "protobuf.h"
> >  #include "images/netdev.pb-c.h"
> > @@ -1661,7 +1662,9 @@ int veth_pair_add(char *in, char *out)
> >  
> >  static int prep_ns_sockets(struct ns_id *ns, bool for_dump)
> >  {
> > -	int nsret = -1, ret;
> > +	int nsret = -1, ret, sk;
> > +	struct sockaddr_un addr;
> > +	s32 addr_len;
> >  
> >  	if (ns->type != NS_CRIU) {
> >  		pr_info("Switching to %d's net for collecting sockets\n", ns->ns_pid);
> > @@ -1678,12 +1681,24 @@ static int prep_ns_sockets(struct ns_id *ns, bool for_dump)
> >  	} else
> >  		ns->net.nlsk = -1;
> >  
> > -	ret = ns->net.seqsk = socket(PF_UNIX, SOCK_SEQPACKET | SOCK_NONBLOCK, 0);
> > -	if (ret < 0) {
> > +	sk = socket(PF_UNIX, SOCK_SEQPACKET | SOCK_NONBLOCK, 0);
> > +	if (sk < 0) {
> >  		pr_perror("Can't create seqsk for parasite");
> >  		goto err_sq;
> >  	}
> >  
> > +	addr_len = gen_parasite_saddr(&addr, getpid());
> > +	if (bind(sk, (struct sockaddr *)&addr, addr_len) < 0) {
> > +		pr_perror("Can't bind socket");
> > +		goto err_ret;
> > +	}
> > +
> > +	if (listen(sk, 1)) {
> > +		pr_perror("Can't listen on transport socket");
> > +		goto err_ret;
> > +	}
> > +
> > +	ns->net.seqsk = sk;
> >  	ret = 0;
> >  out:
> >  	if (nsret >= 0 && restore_ns(nsret, &net_ns_desc) < 0) {
> > @@ -1695,11 +1710,11 @@ out:
> >  	return ret;
> >  
> >  err_ret:
> > -	close(ns->net.seqsk);
> > +	close_safe(&sk);
> >  err_sq:
> > -	if (ns->net.nlsk >= 0)
> > -		close(ns->net.nlsk);
> > +	close_safe(&ns->net.nlsk);
> >  err_nl:
> > +	ret = -1;
> >  	goto out;
> >  }
> >  
> > diff --git a/criu/parasite-syscall.c b/criu/parasite-syscall.c
> > index fb1c245..18923a5 100644
> > --- a/criu/parasite-syscall.c
> > +++ b/criu/parasite-syscall.c
> > @@ -363,7 +363,7 @@ int parasite_execute_daemon(unsigned int cmd, struct parasite_ctl *ctl)
> >  	return ret;
> >  }
> >  
> > -static int gen_parasite_saddr(struct sockaddr_un *saddr, int key)
> > +int gen_parasite_saddr(struct sockaddr_un *saddr, int key)
> >  {
> >  	int sun_len;
> >  
> > @@ -454,25 +454,12 @@ static int restore_child_handler()
> >  static int prepare_tsock(struct parasite_ctl *ctl, pid_t pid,
> >  		struct parasite_init_args *args, struct ns_id *net)
> >  {
> > -	static int ssock = -1;
> > +	int ssock;
> >  
> >  	pr_info("Putting tsock into pid %d\n", pid);
> >  	args->h_addr_len = gen_parasite_saddr(&args->h_addr, getpid());
> >  
> > -	if (ssock == -1) {
> > -		ssock = net->net.seqsk;
> > -		net->net.seqsk = -1;
> > -
> > -		if (bind(ssock, (struct sockaddr *)&args->h_addr, args->h_addr_len) < 0) {
> > -			pr_perror("Can't bind socket");
> > -			goto err;
> > -		}
> > -
> > -		if (listen(ssock, 1)) {
> > -			pr_perror("Can't listen on transport socket");
> > -			goto err;
> > -		}
> > -	}
> > +	ssock = net->net.seqsk;
> >  
> >  	/* Check a case when parasite can't initialize a command socket */
> >  	if (fault_injected(FI_PARASITE_CONNECT))
> > @@ -484,9 +471,6 @@ static int prepare_tsock(struct parasite_ctl *ctl, pid_t pid,
> >  	 */
> >  	ctl->tsock = -ssock;
> >  	return 0;
> > -err:
> > -	close_safe(&ssock);
> > -	return -1;
> >  }
> >  
> >  static int accept_tsock(struct parasite_ctl *ctl)
> > 
>