9p connect fixes

* if we fail in p9_conn_create(), we shouldn't leak references to struct file.
  Logics in ->close() doesn't help - ->trans is already gone by the time it's
  called.
* sock_create_kern() can fail.
* use of sock_map_fd() is all fscked up; I'd fixed most of that, but the
  rest will have to wait for a bit more work in net/socket.c (we still are
  violating the basic rule of working with descriptor table: "once the reference
  is installed there, don't rely on finding it there again").

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

net/9p/trans_fd.c

@@ -42,6 +42,8 @@
 #include <net/9p/client.h>
 #include <net/9p/transport.h>
 
+#include <linux/syscalls.h> /* killme */
+
 #define P9_PORT 564
 #define MAX_SOCK_BUF (64*1024)
 #define MAXPOLLWADDR	2
@@ -788,24 +790,41 @@ static int p9_fd_open(struct p9_client *client, int rfd, int wfd)
 
 static int p9_socket_open(struct p9_client *client, struct socket *csocket)
 {
-	int fd, ret;
+	struct p9_trans_fd *p;
+	int ret, fd;
+
+	p = kmalloc(sizeof(struct p9_trans_fd), GFP_KERNEL);
+	if (!p)
+		return -ENOMEM;
 
 	csocket->sk->sk_allocation = GFP_NOIO;
 	fd = sock_map_fd(csocket, 0);
 	if (fd < 0) {
 		P9_EPRINTK(KERN_ERR, "p9_socket_open: failed to map fd\n");
+		sock_release(csocket);
+		kfree(p);
 		return fd;
 	}
 
-	ret = p9_fd_open(client, fd, fd);
-	if (ret < 0) {
-		P9_EPRINTK(KERN_ERR, "p9_socket_open: failed to open fd\n");
+	get_file(csocket->file);
+	get_file(csocket->file);
+	p->wr = p->rd = csocket->file;
+	client->trans = p;
+	client->status = Connected;
+
+	sys_close(fd);	/* still racy */
+
+	p->rd->f_flags |= O_NONBLOCK;
+
+	p->conn = p9_conn_create(client);
+	if (IS_ERR(p->conn)) {
+		ret = PTR_ERR(p->conn);
+		p->conn = NULL;
+		kfree(p);
+		sockfd_put(csocket);
 		sockfd_put(csocket);
 		return ret;
 	}
-
-	((struct p9_trans_fd *)client->trans)->rd->f_flags |= O_NONBLOCK;
-
 	return 0;
 }
 
@@ -883,7 +902,6 @@ p9_fd_create_tcp(struct p9_client *client, const char *addr, char *args)
 	struct socket *csocket;
 	struct sockaddr_in sin_server;
 	struct p9_fd_opts opts;
-	struct p9_trans_fd *p = NULL; /* this gets allocated in p9_fd_open */
 
 	err = parse_opts(args, &opts);
 	if (err < 0)
@@ -897,12 +915,11 @@ p9_fd_create_tcp(struct p9_client *client, const char *addr, char *args)
 	sin_server.sin_family = AF_INET;
 	sin_server.sin_addr.s_addr = in_aton(addr);
 	sin_server.sin_port = htons(opts.port);
-	sock_create_kern(PF_INET, SOCK_STREAM, IPPROTO_TCP, &csocket);
+	err = sock_create_kern(PF_INET, SOCK_STREAM, IPPROTO_TCP, &csocket);
 
-	if (!csocket) {
+	if (err) {
 		P9_EPRINTK(KERN_ERR, "p9_trans_tcp: problem creating socket\n");
-		err = -EIO;
-		goto error;
+		return err;
 	}
 
 	err = csocket->ops->connect(csocket,
@@ -912,30 +929,11 @@ p9_fd_create_tcp(struct p9_client *client, const char *addr, char *args)
 		P9_EPRINTK(KERN_ERR,
 			"p9_trans_tcp: problem connecting socket to %s\n",
 			addr);
-		goto error;
-	}
-
-	err = p9_socket_open(client, csocket);
-	if (err < 0)
-		goto error;
-
-	p = (struct p9_trans_fd *) client->trans;
-	p->conn = p9_conn_create(client);
-	if (IS_ERR(p->conn)) {
-		err = PTR_ERR(p->conn);
-		p->conn = NULL;
-		goto error;
-	}
-
-	return 0;
-
-error:
-	if (csocket)
 		sock_release(csocket);
+		return err;
+	}
 
-	kfree(p);
-
-	return err;
+	return p9_socket_open(client, csocket);
 }
 
 static int
@@ -944,49 +942,33 @@ p9_fd_create_unix(struct p9_client *client, const char *addr, char *args)
 	int err;
 	struct socket *csocket;
 	struct sockaddr_un sun_server;
-	struct p9_trans_fd *p = NULL; /* this gets allocated in p9_fd_open */
 
 	csocket = NULL;
 
 	if (strlen(addr) > UNIX_PATH_MAX) {
 		P9_EPRINTK(KERN_ERR, "p9_trans_unix: address too long: %s\n",
 			addr);
-		err = -ENAMETOOLONG;
-		goto error;
+		return -ENAMETOOLONG;
 	}
 
 	sun_server.sun_family = PF_UNIX;
 	strcpy(sun_server.sun_path, addr);
-	sock_create_kern(PF_UNIX, SOCK_STREAM, 0, &csocket);
+	err = sock_create_kern(PF_UNIX, SOCK_STREAM, 0, &csocket);
+	if (err < 0) {
+		P9_EPRINTK(KERN_ERR, "p9_trans_unix: problem creating socket\n");
+		return err;
+	}
 	err = csocket->ops->connect(csocket, (struct sockaddr *)&sun_server,
 			sizeof(struct sockaddr_un) - 1, 0);
 	if (err < 0) {
 		P9_EPRINTK(KERN_ERR,
 			"p9_trans_unix: problem connecting socket: %s: %d\n",
 			addr, err);
-		goto error;
-	}
-
-	err = p9_socket_open(client, csocket);
-	if (err < 0)
-		goto error;
-
-	p = (struct p9_trans_fd *) client->trans;
-	p->conn = p9_conn_create(client);
-	if (IS_ERR(p->conn)) {
-		err = PTR_ERR(p->conn);
-		p->conn = NULL;
-		goto error;
-	}
-
-	return 0;
-
-error:
-	if (csocket)
 		sock_release(csocket);
+		return err;
+	}
 
-	kfree(p);
-	return err;
+	return p9_socket_open(client, csocket);
 }
 
 static int
@@ -994,7 +976,7 @@ p9_fd_create(struct p9_client *client, const char *addr, char *args)
 {
 	int err;
 	struct p9_fd_opts opts;
-	struct p9_trans_fd *p = NULL; /* this get allocated in p9_fd_open */
+	struct p9_trans_fd *p;
 
 	parse_opts(args, &opts);
 
@@ -1005,21 +987,19 @@ p9_fd_create(struct p9_client *client, const char *addr, char *args)
 
 	err = p9_fd_open(client, opts.rfd, opts.wfd);
 	if (err < 0)
-		goto error;
+		return err;
 
 	p = (struct p9_trans_fd *) client->trans;
 	p->conn = p9_conn_create(client);
 	if (IS_ERR(p->conn)) {
 		err = PTR_ERR(p->conn);
 		p->conn = NULL;
-		goto error;
+		fput(p->rd);
+		fput(p->wr);
+		return err;
 	}
 
 	return 0;
-
-error:
-	kfree(p);
-	return err;
 }
 
 static struct p9_trans_module p9_tcp_trans = {