tty: notify about orphan tty-s via rpc

Now Docker creates a pty pair from a container devpts to use is as console.
A slave tty is set as a control tty for the init process and bind-mounted
into /dev/console. The master tty is handled externelly.

Now CRIU can handle external resources, but here we have internal resources
which are used externaly.

opencontainers/runc#1202
travis-ci: success for A few fixes to c/r a docker container with a console (rev3)
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>

criu/action-scripts.c

@@ -13,6 +13,9 @@
 #include "pstree.h"
 #include "common/bug.h"
 #include "util.h"
+#include <sys/un.h>
+#include <sys/socket.h>
+#include "common/scm.h"
 
 static const char *action_names[ACT_MAX] = {
 	[ ACT_PRE_DUMP ]	= "pre-dump",
@@ -25,6 +28,7 @@ static const char *action_names[ACT_MAX] = {
 	[ ACT_POST_SETUP_NS ]	= "post-setup-namespaces",
 	[ ACT_PRE_RESUME ]	= "pre-resume",
 	[ ACT_POST_RESUME ]	= "post-resume",
+	[ ACT_ORPHAN_PTS_MASTER ] = "orphan-pts-master",
 };
 
 struct script {
@@ -96,6 +100,17 @@ static int run_shell_scripts(const char *action)
 	return retval;
 }
 
+int rpc_send_fd(enum script_actions act, int fd)
+{
+	const char *action = action_names[act];
+
+	if (scripts_mode != SCRIPTS_RPC)
+		return -1;
+
+	pr_debug("\tRPC\n");
+	return send_criu_rpc_script(act, (char *)action, rpc_sk, fd);
+}
+
 int run_scripts(enum script_actions act)
 {
 	int ret = 0;
@@ -108,7 +123,7 @@ int run_scripts(enum script_actions act)
 
 	if (scripts_mode == SCRIPTS_RPC) {
 		pr_debug("\tRPC\n");
-		ret = send_criu_rpc_script(act, (char *)action, rpc_sk);
+		ret = send_criu_rpc_script(act, (char *)action, rpc_sk, -1);
 		goto out;
 	}
 
@@ -146,6 +161,7 @@ int add_rpc_notify(int sk)
 	BUG_ON(scripts_mode == SCRIPTS_SHELL);
 	scripts_mode = SCRIPTS_RPC;
 
-	rpc_sk = sk;
+	rpc_sk = install_service_fd(RPC_SK_OFF, sk);
+
 	return 0;
 }

criu/cr-restore.c

@@ -3045,6 +3045,7 @@ static int sigreturn_restore(pid_t pid, struct task_restore_args *task_args, uns
 	close_proc();
 	close_service_fd(ROOT_FD_OFF);
 	close_service_fd(USERNSD_SK);
+	close_service_fd(RPC_SK_OFF);
 
 	__gcov_flush();
 

criu/cr-service.c

@@ -36,6 +36,9 @@
 #include "irmap.h"
 #include "kerndat.h"
 #include "proc_parse.h"
+#include <sys/un.h>
+#include <sys/socket.h>
+#include "common/scm.h"
 
 #include "setproctitle.h"
 
@@ -84,10 +87,10 @@ static int recv_criu_msg(int socket_fd, CriuReq **req)
 	return -1;
 }
 
-static int send_criu_msg(int socket_fd, CriuResp *msg)
+static int send_criu_msg_with_fd(int socket_fd, CriuResp *msg, int fd)
 {
 	unsigned char *buf;
-	int len;
+	int len, ret;
 
 	len = criu_resp__get_packed_size(msg);
 
@@ -100,7 +103,11 @@ static int send_criu_msg(int socket_fd, CriuResp *msg)
 		goto err;
 	}
 
-	if (write(socket_fd, buf, len)  == -1) {
+	if (fd >= 0) {
+		ret = send_fds(socket_fd, NULL, 0, &fd, 1, buf, len);
+	} else
+		ret = write(socket_fd, buf, len);
+	if (ret < 0) {
 		pr_perror("Can't send response");
 		goto err;
 	}
@@ -112,6 +119,11 @@ static int send_criu_msg(int socket_fd, CriuResp *msg)
 	return -1;
 }
 
+static int send_criu_msg(int socket_fd, CriuResp *msg)
+{
+	return send_criu_msg_with_fd(socket_fd, msg, -1);
+}
+
 static void set_resp_err(CriuResp *resp)
 {
 	resp->cr_errno = get_cr_errno();
@@ -174,7 +186,7 @@ int send_criu_restore_resp(int socket_fd, bool success, int pid)
 	return send_criu_msg(socket_fd, &msg);
 }
 
-int send_criu_rpc_script(enum script_actions act, char *name, int fd)
+int send_criu_rpc_script(enum script_actions act, char *name, int sk, int fd)
 {
 	int ret;
 	CriuResp msg = CRIU_RESP__INIT;
@@ -201,11 +213,11 @@ int send_criu_rpc_script(enum script_actions act, char *name, int fd)
 		break;
 	}
 
-	ret = send_criu_msg(fd, &msg);
+	ret = send_criu_msg_with_fd(sk, &msg, fd);
 	if (ret < 0)
 		return ret;
 
-	ret = recv_criu_msg(fd, &req);
+	ret = recv_criu_msg(sk, &req);
 	if (ret < 0)
 		return ret;
 
@@ -512,6 +524,9 @@ static int setup_opts_from_req(int sk, CriuOpts *req)
 			goto err;
 	}
 
+	if (req->orphan_pts_master)
+		opts.orphan_pts_master = true;
+
 	if (check_namespace_opts())
 		goto err;
 

criu/include/action-scripts.h

@@ -1,6 +1,8 @@
 #ifndef __CR_ACTION_SCRIPTS_H__
 #define __CR_ACTION_SCRIPTS_H__
 
+#include "asm/int.h"
+
 enum script_actions {
 	ACT_PRE_DUMP,
 	ACT_POST_DUMP,
@@ -12,13 +14,15 @@ enum script_actions {
 	ACT_POST_SETUP_NS,
 	ACT_POST_RESUME,
 	ACT_PRE_RESUME,
+	ACT_ORPHAN_PTS_MASTER,
 
 	ACT_MAX
 };
 
 extern int add_script(char *path);
 extern int add_rpc_notify(int sk);
 extern int run_scripts(enum script_actions);
-extern int send_criu_rpc_script(enum script_actions act, char *name, int arg);
+extern int rpc_send_fd(enum script_actions, int fd);
+extern int send_criu_rpc_script(enum script_actions act, char *name, int sk, int fd);
 
 #endif /* __CR_ACTION_SCRIPTS_H__ */

criu/include/cr_options.h

@@ -118,6 +118,7 @@ struct cr_options {
 	bool			display_stats;
 	bool			weak_sysctls;
 	int			status_fd;
+	bool			orphan_pts_master;
 };
 
 extern struct cr_options opts;

criu/include/servicefd.h

@@ -20,6 +20,7 @@ enum sfd_type {
 	USERNSD_SK,	/* Socket for usernsd */
 	NS_FD_OFF,	/* Node's net namespace fd */
 	TRANSPORT_FD_OFF, /* to transfer file descriptors */
+	RPC_SK_OFF,
 
 	SERVICE_FD_MAX
 };

criu/tty.c

@@ -28,6 +28,7 @@
 #include "files-reg.h"
 #include "namespaces.h"
 #include "external.h"
+#include "action-scripts.h"
 
 #include "protobuf.h"
 #include "util.h"
@@ -376,7 +377,7 @@ static int tty_verify_active_pairs(void * unused)
 				continue;
 			}
 
-			if (!opts.shell_job) {
+			if (!opts.shell_job && !opts.orphan_pts_master) {
 				pr_err("Found slave peer index %d without "
 				       "correspond master peer\n",
 				       tty_get_index(i));
@@ -688,7 +689,7 @@ int tty_restore_ctl_terminal(struct file_desc *d, int fd)
 	else
 		index = driver->index;
 
-	if (is_pty(info->driver)) {
+	if (is_pty(info->driver) && tty_is_master(info)) {
 		fake = pty_alloc_fake_slave(info);
 		if (!fake)
 			goto err;
@@ -956,6 +957,32 @@ static int pty_open_unpaired_slave(struct file_desc *d, struct tty_info *slave)
 	 */
 
 	if (likely(slave->inherit)) {
+		if (opts.orphan_pts_master) {
+			fake = pty_alloc_fake_master(slave);
+			if (!fake)
+				goto err;
+			master = pty_open_ptmx_index(&fake->d, slave, O_RDWR);
+			if (master < 0) {
+				pr_err("Can't open master pty %x (index %d)\n",
+					  slave->tfe->id, slave->tie->pty->index);
+				goto err;
+			}
+
+			unlock_pty(master);
+
+			if (opts.orphan_pts_master &&
+			    rpc_send_fd(ACT_ORPHAN_PTS_MASTER, master) == 0) {
+
+				fd = open_tty_reg(slave->reg_d, slave->tfe->flags);
+				if (fd < 0) {
+					pr_err("Can't open slave pty %s\n", path_from_reg(slave->reg_d));
+					goto err;
+				}
+
+				goto out;
+			}
+		}
+
 		if (!stdin_isatty) {
 			pr_err("Don't have tty to inherit session from, aborting\n");
 			return -1;
@@ -990,6 +1017,7 @@ static int pty_open_unpaired_slave(struct file_desc *d, struct tty_info *slave)
 
 	}
 
+out:
 	if (restore_tty_params(fd, slave))
 		goto err;
 
@@ -1002,7 +1030,7 @@ static int pty_open_unpaired_slave(struct file_desc *d, struct tty_info *slave)
 	 * be already restored properly thus we can simply
 	 * use syscalls instead of lookup via process tree.
 	 */
-	if (likely(slave->inherit)) {
+	if (slave->inherit && opts.shell_job) {
 		/*
 		 * The restoration procedure only works if we're
 		 * migrating not a session leader, otherwise it's
@@ -1241,8 +1269,10 @@ static int tty_find_restoring_task(struct tty_info *info)
 		if (!tty_is_master(info)) {
 			if (tty_has_active_pair(info))
 				return 0;
-			else
+			else if (!opts.orphan_pts_master)
 				goto shell_job;
+			else
+				info->inherit = true;
 		}
 
 		/*
@@ -1366,7 +1396,7 @@ static int tty_setup_slavery(void * unused)
 		    info->driver->type == TTY_TYPE__CTTY)
 			continue;
 
-		if (!tty_is_master(info))
+		if (!tty_is_master(info) && info->link)
 			continue;
 
 		info->ctl_tty = info;

images/rpc.proto

@@ -109,6 +109,7 @@ message criu_opts {
 	optional bool			tcp_skip_in_flight	= 46;
 	optional bool			weak_sysctls		= 47;
 	optional int32			status_fd		= 49;
+	optional bool			orphan_pts_master	= 50;
 }
 
 message criu_dump_resp {