unix: Add support for shutdown sockets

Get the info from kernel diag message (it should always be there)
and restore the shutdown at the very end.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

include/sockets.h

@@ -2,6 +2,7 @@
 #define CR_SOCKETS_H__
 
 #include <sys/types.h>
+#include <sys/socket.h>
 #include <unistd.h>
 #include <stdbool.h>
 
@@ -59,5 +60,20 @@ extern int do_dump_opt(int sk, int level, int name, void *val, int len);
 extern int do_restore_opt(int sk, int level, int name, void *val, int len);
 #define restore_opt(s, l, n, f)	do_restore_opt(s, l, n, f, sizeof(*f))
 
+#define sk_encode_shutdown(img, mask) do {			\
+		/* 						\
+		 * protobuf SK_SHUTDOWN__ bits match those	\
+		 * reported by kernel				\
+		 */ 						\
+		(img)->shutdown = mask;				\
+		if ((img)->shutdown != SK_SHUTDOWN__NONE)	\
+			(img)->has_shutdown = true;		\
+	} while (0)
+
+static inline int sk_decode_shutdown(int val)
+{
+	static const int hows[] = {-1, SHUT_RD, SHUT_WR, SHUT_RDWR};
+	return hows[val];
+}
 
 #endif /* CR_SOCKETS_H__ */

include/unix_diag.h

@@ -49,6 +49,7 @@ enum {
 	UNIX_DIAG_ICONS,
 	UNIX_DIAG_RQLEN,
 	UNIX_DIAG_MEMINFO,
+	UNIX_DIAG_SHUTDOWN,
 
 	UNIX_DIAG_MAX,
 };

protobuf/sk-opts.proto

@@ -18,3 +18,10 @@ message sk_opts_entry {
 
 	optional uint32		so_bound_dev	= 15;
 }
+
+enum sk_shutdown {
+	NONE = 0;
+	READ = 1;
+	WRITE = 2;
+	BOTH = 3;
+}

protobuf/sk-unix.proto

@@ -29,4 +29,6 @@ message unix_sk_entry {
 	 * so we need to carry it as byte sequence...
 	 */
 	required bytes			name		= 11;
+
+	optional sk_shutdown		shutdown	= 12;
 }

sk-unix.c

@@ -36,6 +36,7 @@ struct unix_sk_desc {
 	char			*name;
 	unsigned int		nr_icons;
 	unsigned int		*icons;
+	unsigned char		shutdown;
 	struct list_head	list;
 };
 
@@ -138,6 +139,8 @@ static int dump_one_unix_fd(int lfd, u32 id, const struct fd_parms *p)
 	ue.opts		= &skopts;
 	ue.uflags	= 0;
 
+	sk_encode_shutdown(&ue, sk->shutdown);
+
 	if (ue.peer) {
 		struct unix_sk_desc *peer;
 
@@ -168,6 +171,22 @@ static int dump_one_unix_fd(int lfd, u32 id, const struct fd_parms *p)
 				list_add_tail(&peer->list, &unix_sockets);
 			}
 		}
+
+		if ((ue.type != SOCK_DGRAM) && (
+				((ue.shutdown == SK_SHUTDOWN__READ)  &&
+				 (peer->shutdown != SK_SHUTDOWN__WRITE)) ||
+				((ue.shutdown == SK_SHUTDOWN__WRITE) &&
+				 (peer->shutdown != SK_SHUTDOWN__READ))  ||
+				((ue.shutdown == SK_SHUTDOWN__BOTH)  &&
+				 (peer->shutdown != SK_SHUTDOWN__BOTH)) )) {
+			/*
+			 * On restore we assume, that stream pairs must
+			 * be shut down from one end only
+			 */
+			pr_err("Shutdown mismatch %u:%d -> %u:%d\n",
+					ue.ino, ue.shutdown, peer->sd.ino, peer->shutdown);
+			goto err;
+		}
 	} else if (ue.state == TCP_ESTABLISHED) {
 		const struct unix_sk_listen_icon *e;
 
@@ -248,6 +267,13 @@ static int unix_collect_one(const struct unix_diag_msg *m,
 	d->state = m->udiag_state;
 	INIT_LIST_HEAD(&d->list);
 
+	if (!tb[UNIX_DIAG_SHUTDOWN]) {
+		pr_err("No socket shutdown info\n");
+		goto err;
+	}
+
+	d->shutdown = *(u8 *)RTA_DATA(tb[UNIX_DIAG_SHUTDOWN]);
+
 	if (tb[UNIX_DIAG_PEER])
 		d->peer_ino = *(int *)RTA_DATA(tb[UNIX_DIAG_PEER]);
 
@@ -456,6 +482,24 @@ void show_unixsk(int fd, struct cr_options *o)
 	pb_show_plain_pretty(fd, PB_UNIXSK, "1:%#x 2:%#x 3:%d 4:%d 5:%d 6:%d 7:%d 8:%#x 11:S");
 }
 
+static int shutdown_unix_sk(int sk, struct unix_sk_info *ui)
+{
+	int how;
+	UnixSkEntry *ue = ui->ue;
+
+	if (!ue->has_shutdown || ue->shutdown == SK_SHUTDOWN__NONE)
+		return 0;
+
+	how = sk_decode_shutdown(ue->shutdown);
+	if (shutdown(sk, how)) {
+		pr_perror("Can't shutdown unix socket");
+		return -1;
+	}
+
+	pr_debug("Socket %#x is shut down %d\n", ue->ino, how);
+	return 0;
+}
+
 static int post_open_unix_sk(struct file_desc *d, int fd)
 {
 	struct unix_sk_info *ui;
@@ -500,6 +544,9 @@ static int post_open_unix_sk(struct file_desc *d, int fd)
 	if (restore_socket_opts(fle->fe->fd, ui->ue->opts))
 		return -1;
 
+	if (shutdown_unix_sk(fle->fe->fd, ui))
+		return -1;
+
 	return 0;
 }
 
@@ -566,6 +613,9 @@ static int open_unixsk_pair_master(struct unix_sk_info *ui)
 	if (rst_file_params(sk[0], ui->ue->fown, ui->ue->flags))
 		return -1;
 
+	if (shutdown_unix_sk(sk[0], ui))
+		return -1;
+
 	tsk = socket(PF_UNIX, SOCK_DGRAM, 0);
 	if (tsk < 0) {
 		pr_perror("Can't make transport socket");
@@ -610,6 +660,14 @@ static int open_unixsk_pair_slave(struct unix_sk_info *ui)
 	if (restore_socket_opts(sk, ui->ue->opts))
 		return -1;
 
+	if (ui->ue->type == SOCK_DGRAM)
+		/*
+		 * Stream socket's "slave" end will be shut down
+		 * together with master
+		 */
+		if (shutdown_unix_sk(sk, ui))
+			return -1;
+
 	return sk;
 }