[CRIU] [PATCH v5 10/11] unix: Correctly restore DGRAM promiscuos queue

[Kirill Tkhai]

In case of DGRAM, bound, queuerless sockets, restore
their queues using restore_promisc_queue().

This function forces to use socket address, and
do not pass a queuer_fd. The last leads to that
fd, used for sendto(), will be choosen by get_pkt_sender_fd(),
and correct pkt msg name will be restored.

v5: New

Signed-off-by: Kirill Tkhai <ktkhai at virtuozzo.com>
---
 criu/include/sk-queue.h |    1 +
 criu/sk-queue.c         |   15 ++++++++++-
 criu/sk-unix.c          |   63 ++++++++++++++++++++++++++++++++++++++++++++++-
 3 files changed, 76 insertions(+), 3 deletions(-)

diff --git a/criu/include/sk-queue.h b/criu/include/sk-queue.h
index a16edc6..78a5677 100644
--- a/criu/include/sk-queue.h
+++ b/criu/include/sk-queue.h
@@ -13,6 +13,7 @@ struct sk_packet {
 };
 
 extern struct list_head packets_list;
+extern int get_pkt_sender_fd(SkPacketEntry *entry, int *noname_fd);
 
 extern struct collect_image_info sk_queues_cinfo;
 extern int dump_sk_queue(int sock_fd, int sock_id, u64 (*get_sender)(const char *, int));
diff --git a/criu/sk-queue.c b/criu/sk-queue.c
index 9e9a484..d0e5862 100644
--- a/criu/sk-queue.c
+++ b/criu/sk-queue.c
@@ -192,11 +192,12 @@ int __restore_sk_queue(int queuer_fd, unsigned int peer_id, struct sockaddr *dst
 {
 	struct sk_packet *pkt, *tmp;
 	struct cr_img *img;
+	int noname_fd = -1;
 	int fd, ret;
 
 	pr_info("Trying to restore recv queue for %u\n", peer_id);
 
-	if (restore_prepare_socket(queuer_fd) < 0)
+	if (queuer_fd >=0 && restore_prepare_socket(queuer_fd) < 0)
 		return -1;
 
 	img = open_image(CR_FD_SK_QUEUES, O_RSTR);
@@ -235,7 +236,14 @@ int __restore_sk_queue(int queuer_fd, unsigned int peer_id, struct sockaddr *dst
 			goto err;
 		}
 
-		fd = queuer_fd;
+		if (queuer_fd >= 0)
+			fd = queuer_fd;
+		else
+			fd = get_pkt_sender_fd(entry, &noname_fd);
+		if (fd < 0) {
+			ret = -1;
+			goto err;
+		}
 		ret = sendto(fd, buf, entry->length, 0, dst_addr, dst_addrlen);
 		xfree(buf);
 		if (ret < 0) {
@@ -252,6 +260,9 @@ int __restore_sk_queue(int queuer_fd, unsigned int peer_id, struct sockaddr *dst
 		xfree(pkt);
 	}
 
+	if (noname_fd >= 0)
+		close(noname_fd);
+
 	close_image(img);
 	return 0;
 err:
diff --git a/criu/sk-unix.c b/criu/sk-unix.c
index b221a71..759a261 100644
--- a/criu/sk-unix.c
+++ b/criu/sk-unix.c
@@ -907,6 +907,63 @@ static int prep_unix_sk_cwd(struct unix_sk_info *ui, int *prev_cwd_fd)
 	return 0;
 }
 
+static struct file_desc_ops unix_desc_ops;
+
+int get_pkt_sender_fd(SkPacketEntry *e, int *noname_fd)
+{
+	struct fdinfo_list_entry *fle;
+	struct unix_sk_info *ui;
+	u32 ino;
+
+	if (!e->has_sender_ino) {
+		if (*noname_fd >= 0)
+			return *noname_fd;
+		*noname_fd = socket(AF_UNIX, SOCK_DGRAM, 0);
+		return *noname_fd;
+	}
+
+	ino = e->sender_ino;
+
+	list_for_each_entry(fle, &rsti(current)->used, used_list) {
+		if (fle->desc->ops != &unix_desc_ops)
+			continue;
+		ui = container_of(fle->desc, struct unix_sk_info, d);
+		if (ui->ue->ino != ino || ui->ue->type != SOCK_DGRAM)
+			continue;
+		if (!list_empty(&ui->d.fd_info_head))
+			futex_wait_while(&ui->prepared, 0);
+		return fle->fe->fd;
+	}
+
+	pr_err("Can't find sender fd: pid=%u, ino=%u\n", current->pid.virt, ino);
+	return -1;
+}
+
+static int restore_promisc_queue(struct unix_sk_info *ui, int fd)
+{
+	struct sockaddr_un addr;
+	socklen_t addrlen;
+	int cwd_fd = -1;
+
+	addrlen = ui->ue->name.len + sizeof(addr.sun_family);
+	memcpy(&addr.sun_path, ui->ue->name.data, ui->ue->name.len);
+	addr.sun_family = AF_UNIX;
+
+	if (prep_unix_sk_cwd(ui, &cwd_fd))
+		return -1;
+
+	if (__restore_sk_queue(-1, ui->ue->id,
+			       (struct sockaddr *)&addr, addrlen) < 0) {
+		pr_err("Can't restore rcv queue\n");
+		revert_unix_sk_cwd(&cwd_fd);
+		return -1;
+	}
+
+	revert_unix_sk_cwd(&cwd_fd);
+
+	return 0;
+}
+
 static int post_open_unix_sk(struct file_desc *d, int fd)
 {
 	struct unix_sk_info *ui;
@@ -918,6 +975,10 @@ static int post_open_unix_sk(struct file_desc *d, int fd)
 	if (ui->flags & (USK_PAIR_MASTER | USK_PAIR_SLAVE))
 		return 0;
 
+	if (ui->ue->type == SOCK_DGRAM && !ui->queuer && ui->ue->name.len &&
+	    restore_promisc_queue(ui, fd))
+		return -1;
+
 	peer = ui->peer;
 
 	if (peer == NULL)
@@ -1177,7 +1238,7 @@ static int open_unixsk_standalone(struct unix_sk_info *ui)
 
 		close(sks[1]);
 		sk = sks[0];
-	} else if (ui->ue->type == SOCK_DGRAM && !ui->queuer) {
+	} else if (ui->ue->type == SOCK_DGRAM && !ui->queuer && !ui->ue->name.len) {
 		struct sockaddr_un addr;
 		int sks[2];