tcp: Prepare sk-inet for dumping and restoring tcp connections

First of all -- to make crtools dump/restore established tcp sockets
you have to specify the --tcp-established options. By doing so you
inform crtools that

a) you know, that after dump there will be a netfilter rules blocking
   the dumped connections

b) you guarantee, that before restore this netfilter block is still
   there

What else this patch does is simple -- collects establised sockets and
calls the dump/restore tcp function (now empty) where appropriate.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

crtools.c

@@ -22,6 +22,8 @@
 #include "syscall.h"
 #include "uts_ns.h"
 #include "ipc_ns.h"
+#include "files.h"
+#include "sk-inet.h"
 
 struct cr_options opts;
 
@@ -347,6 +349,7 @@ int main(int argc, char *argv[])
 			{ "namespaces", required_argument, 0, 'n' },
 			{ "ext-unix-sk", no_argument, 0, 'x' },
 			{ "help", no_argument, 0, 'h' },
+			{ SK_EST_PARAM, no_argument, 0, 42 },
 			{ },
 		};
 
@@ -410,6 +413,10 @@ int main(int argc, char *argv[])
 					log_level++;
 			}
 			break;
+		case 42:
+			pr_info("Will dump TCP connections\n");
+			opts.tcp_established_ok = true;
+			break;
 		case 'h':
 		default:
 			goto usage;

include/crtools.h

@@ -66,6 +66,7 @@ struct cr_options {
 	bool			show_pages_content;
 	bool			restore_detach;
 	bool			ext_unix_sk;
+	bool			tcp_established_ok;
 	unsigned int		namespaces_flags;
 };
 

include/sk-inet.h

@@ -23,4 +23,16 @@ struct inet_sk_info {
 
 int inet_bind(int sk, struct inet_sk_info *);
 int inet_connect(int sk, struct inet_sk_info *);
+
+static inline int dump_one_tcp(int sk, struct inet_sk_desc *sd)
+{
+	return -1;
+}
+
+static inline int restore_one_tcp(int sk, struct inet_sk_info *si)
+{
+	return -1;
+}
+
+#define SK_EST_PARAM	"tcp-established"
 #endif

include/sockets.h

@@ -39,7 +39,7 @@ struct socket_desc {
 struct socket_desc *lookup_socket(int ino);
 int sk_collect_one(int ino, int family, struct socket_desc *d);
 int dump_one_inet(struct socket_desc *_sk, struct fd_parms *p,
-			 const struct cr_fdset *cr_fdset);
+		int lfd, const struct cr_fdset *cr_fdset);
 int dump_one_unix(const struct socket_desc *_sk, struct fd_parms *p,
 		int lfd, const struct cr_fdset *cr_fdset);
 struct nlmsghdr;

sk-inet.c

@@ -72,6 +72,13 @@ static int can_dump_inet_sk(const struct inet_sk_desc *sk)
 			return 0;
 		}
 		break;
+	case TCP_ESTABLISHED:
+		if (!opts.tcp_established_ok) {
+			pr_err("Connected TCP socket, consider using %s option.\n",
+					SK_EST_PARAM);
+			return 0;
+		}
+		break;
 	default:
 		pr_err("Unknown state %d\n", sk->state);
 		return 0;
@@ -80,8 +87,11 @@ static int can_dump_inet_sk(const struct inet_sk_desc *sk)
 	return 1;
 }
 
+#define tcp_connection(sk)	(((sk)->proto == IPPROTO_TCP) &&	\
+				 ((sk)->state == TCP_ESTABLISHED))
+
 int dump_one_inet(struct socket_desc *_sk, struct fd_parms *p,
-			 const struct cr_fdset *cr_fdset)
+		int lfd, const struct cr_fdset *cr_fdset)
 {
 	struct inet_sk_desc *sk = (struct inet_sk_desc *)_sk;
 	struct inet_sk_entry ie;
@@ -123,6 +133,10 @@ int dump_one_inet(struct socket_desc *_sk, struct fd_parms *p,
 	show_one_inet("Dumping", sk);
 	show_one_inet_img("Dumped", &ie);
 	sk->sd.already_dumped = 1;
+
+	if (tcp_connection(sk))
+		return dump_one_tcp(lfd, sk);
+
 	return 0;
 
 err:
@@ -221,6 +235,18 @@ static int open_inet_sk(struct file_desc *d)
 		return -1;
 	}
 
+	if (tcp_connection(&ii->ie)) {
+		if (!opts.tcp_established_ok) {
+			pr_err("Connected TCP socket in image\n");
+			goto err;
+		}
+
+		if (restore_one_tcp(sk, ii))
+			goto err;
+
+		goto done;
+	}
+
 	/*
 	 * Listen sockets are easiest ones -- simply
 	 * bind() and listen(), and that's all.
@@ -244,7 +270,7 @@ static int open_inet_sk(struct file_desc *d)
 	if (ii->ie.state == TCP_ESTABLISHED &&
 			inet_connect(sk, ii))
 		goto err;
-
+done:
 	if (rst_file_params(sk, &ii->ie.fown, ii->ie.flags))
 		goto err;
 

sockets.c

@@ -81,7 +81,7 @@ int dump_socket(struct fd_parms *p, int lfd, const struct cr_fdset *cr_fdset)
 		return dump_one_unix(sk, p, lfd, cr_fdset);
 	case AF_INET:
 	case AF_INET6:
-		return dump_one_inet(sk, p, cr_fdset);
+		return dump_one_inet(sk, p, lfd, cr_fdset);
 	default:
 		pr_err("BUG! Unknown socket collected\n");
 		break;
@@ -220,8 +220,8 @@ int collect_sockets(void)
 	req.r.i.sdiag_family	= AF_INET;
 	req.r.i.sdiag_protocol	= IPPROTO_TCP;
 	req.r.i.idiag_ext	= 0;
-	/* Only listening sockets supported yet */
-	req.r.i.idiag_states	= 1 << TCP_LISTEN;
+	/* Only listening and established sockets supported yet */
+	req.r.i.idiag_states	= (1 << TCP_LISTEN) | (1 << TCP_ESTABLISHED);
 	tmp = collect_sockets_nl(nl, &req, sizeof(req), inet_tcp_receive_one);
 	if (tmp)
 		err = tmp;