>From 236bcec849c5775a4567c7d8fbceb75beb29dc48 Mon Sep 17 00:00:00 2001
From: Sergiu Ivanov <unlimitedscol...@gmail.com>
Date: Sun, 5 Jul 2009 23:08:44 +0300
Subject: [PATCH] Start the mountee in a lazy fashion.
* mount.c (unionmount_proxy): New variable.
(mountee_port): Likewise.
(mountee_started): Likewise.
(setup_unionmount): New function.
(start_mountee): New function (based on node_set_translator
in nsmux).
* mount.h (unionmount_proxy): New variable.
(mountee_port): Likewise.
(mountee_started): Likewise.
(setup_unionmount): New function.
(start_mountee): New function.
(setup_unionmount): New function.
* netfs.c (netfs_validate_stat): Start the mountee at the
first invocation.
---
mount.c | 179 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
mount.h | 23 ++++++++
netfs.c | 14 +++++-
3 files changed, 215 insertions(+), 1 deletions(-)
diff --git a/mount.c b/mount.c
index 7bc1fb8..f05fe7c 100644
--- a/mount.c
+++ b/mount.c
@@ -22,8 +22,187 @@
#define _GNU_SOURCE
+#include <hurd/fsys.h>
+#include <fcntl.h>
+
#include "mount.h"
+#include "lib.h"
/* The command line for starting the mountee. */
char * mountee_argz;
size_t mountee_argz_len;
+
+/* The node the mountee is sitting on. */
+node_t * unionmount_proxy;
+
+mach_port_t mountee_port;
+
+int mountee_started = 0;
+
+/* Starts the mountee (given by `argz` and `argz_len`), sets it on
+ node `np` and opens a port `port` to with `flags`. */
+error_t
+start_mountee (node_t * np, char * argz, size_t argz_len, int flags,
+ mach_port_t * port)
+{
+ error_t err;
+ mach_port_t underlying_port;
+
+ /* The intermediate container for the port to the root of the
+ mountee. */
+ mach_port_t res_port;
+
+ /* An unauthenticated port to the root of the translator, which
+ plays the role of the directory containing the underlying node of
+ the mountee. This one is used in fsys_getroot as the dotdot
+ parameter, so it is not really important what we put here because
+ the dotdot parameter is used mostly with symlinks. */
+ mach_port_t unauth_dir;
+
+ /* The control port of the mountee. */
+ mach_port_t control;
+
+ /* The user which has created this process. */
+ struct iouser * user;
+
+ /* The user who has no priveleges at all. */
+ struct iouser * nobody;
+
+ /* A protid which will be created from the supplied node. */
+ struct protid * newpi;
+
+ /* Identity information about the current process (for
+ fsys_getroot). */
+ uid_t * uids;
+ size_t nuids;
+
+ gid_t * gids;
+ size_t ngids;
+
+ /* The retry information returned by fsys_getroot. */
+ string_t retry_name;
+ mach_port_t retry_port;
+
+ /* Fetch the effective UIDs of this process. */
+ nuids = geteuids (0, 0);
+ if (nuids < 0)
+ return EPERM;
+ uids = alloca (nuids * sizeof (uid_t));
+
+ nuids = geteuids (nuids, uids);
+ assert (nuids > 0);
+
+ /* Fetch the effective GIDs of this process. */
+ ngids = getgroups (0, 0);
+ if (ngids < 0)
+ return EPERM;
+ gids = alloca (ngids * sizeof (gid_t));
+
+ ngids = getgroups (ngids, gids);
+ assert (ngids > 0);
+
+ /* Create an iouser instance basing on the obtained authority
+ information. */
+ err = iohelp_create_complex_iouser (&user, uids, nuids, gids, ngids);
+ if (err)
+ return err;
+
+ /* Opens the port on which to set the mountee. */
+ error_t
+ open_port (int flags, mach_port_t * underlying,
+ mach_msg_type_name_t * underlying_type, task_t task,
+ void *cookie)
+ {
+ err = 0;
+
+ /* Create a port to `np`. */
+ newpi = netfs_make_protid
+ (netfs_make_peropen (np, flags, NULL), user);
+ if (!newpi)
+ {
+ iohelp_free_iouser (user);
+ return errno;
+ }
+
+ *underlying = underlying_port = ports_get_send_right (newpi);
+ *underlying_type = MACH_MSG_TYPE_COPY_SEND;
+
+ ports_port_deref (newpi);
+
+ return err;
+ } /*open_port */
+
+ /* Create a completely unprivileged user. */
+ err = iohelp_create_iouser(&nobody, NULL, NULL);
+
+ /* Create a port to `np` for the unprivileged user. */
+ newpi = netfs_make_protid
+ (netfs_make_peropen (np, flags, NULL), nobody);
+ if (!newpi)
+ {
+ iohelp_free_iouser (nobody);
+ err = errno;
+ return err;
+ }
+
+ unauth_dir = ports_get_send_right (newpi);
+ ports_port_deref (newpi);
+
+ /* Start the translator. The value 60000 for the timeout is the one
+ found in settrans. */
+ err = fshelp_start_translator (open_port, NULL, argz, argz, argz_len,
+ 60000, &control);
+ if (err)
+ return err;
+
+ /* Attempt to attach the mountee to the port opened in the previous
+ call. */
+ err = file_set_translator (underlying_port, 0, FS_TRANS_SET, 0, argz,
+ argz_len, control, MACH_MSG_TYPE_COPY_SEND);
+ port_dealloc (underlying_port);
+ if (err)
+ return err;
+
+ /* Obtain the port to the root of the newly-set translator. */
+ err = fsys_getroot (control, unauth_dir, MACH_MSG_TYPE_COPY_SEND,
+ uids, nuids, gids, ngids, flags, &retry_port,
+ retry_name, &res_port);
+ if (err)
+ return err;
+
+ *port = res_port;
+
+ return 0;
+} /* start_mountee */
+
+/* Sets up a proxy node, sets the translator on it, and registers the
+ filesystem published by the translator in the list of merged
+ filesystems. */
+error_t
+setup_unionmount (void)
+{
+ error_t err = 0;
+
+ /* The proxy node on which the mountee will be sitting must be able
+ to forward some of the RPCs coming from the mountee to the
+ underlying filesystem. That is why we create this proxy node as
+ a clone of the root node: the mountee will feel as if there is no
+ unionfs under itself. */
+ unionmount_proxy = netfs_make_node (netfs_root_node->nn);
+ if (!unionmount_proxy)
+ return ENOMEM;
+
+ /* Set the mountee on the proxy node.
+ Note that the O_READ flag does not actually limit access to the
+ mountee's filesystem considerably. Whenever a client looks up a
+ node which is not a directory, unionfs will give off a port to
+ the node itself, withouth proxying it. Proxying happens only for
+ directory nodes. */
+ err = start_mountee (unionmount_proxy, mountee_argz,
+ mountee_argz_len, O_READ, &mountee_port);
+
+ mountee_started = 1;
+
+ return err;
+} /* setup_unionmount */
+
diff --git a/mount.h b/mount.h
index a7dd933..181608c 100644
--- a/mount.h
+++ b/mount.h
@@ -23,10 +23,33 @@
#ifndef INCLUDED_MOUNT_H
#define INCLUDED_MOUNT_H
+#include <error.h>
#include <unistd.h>
+#include <hurd/hurd_types.h>
+
+#include "node.h"
/* The command line for starting the mountee. */
extern char * mountee_argz;
extern size_t mountee_argz_len;
+/* The node the mountee is sitting on. */
+extern node_t * unionmount_proxy;
+
+extern mach_port_t mountee_port;
+
+extern int mountee_started;
+
+/* Starts the mountee (given by `argz` and `argz_len`), sets it on
+ node `np` and opens a port `port` to with `flags`. */
+error_t
+start_mountee (node_t * np, char * argz, size_t argz_len, int flags,
+ mach_port_t * port);
+
+/* Sets up a proxy node, sets the translator on it, and registers the
+ filesystem published by the translator in the list of merged
+ filesystems. */
+error_t
+setup_unionmount (void);
+
#endif /* not INCLUDED_MOUNT_H */
diff --git a/netfs.c b/netfs.c
index 89d1bf6..01e8ae9 100644
--- a/netfs.c
+++ b/netfs.c
@@ -1,7 +1,11 @@
/* Hurd unionfs
- Copyright (C) 2001, 2002, 2003, 2005 Free Software Foundation, Inc.
+ Copyright (C) 2001, 2002, 2003, 2005, 2009
+ Free Software Foundation, Inc.
+
Written by Moritz Schulte <mor...@duesseldorf.ccc.de>.
+ Adapted for unionmount by Sergiu Ivanov <unlimitedscol...@gmail.com>.
+
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License as
published by the Free Software Foundation; either version 2 of the
@@ -36,6 +40,7 @@
#include "lib.h"
#include "ncache.h"
#include "options.h"
+#include "mount.h"
/* Return an argz string describing the current options. Fill *ARGZ
with a pointer to newly malloced storage holding the list and *LEN
@@ -165,6 +170,13 @@ netfs_validate_stat (struct node *np, struct iouser *cred)
}
else
{
+ if (!mountee_started)
+ {
+ err = setup_unionmount ();
+ if (err)
+ error (EXIT_FAILURE, err, "failed to setup the mountee");
+ }
+
_get_node_size (np, &np->nn_stat.st_size);
}
--
1.5.2.4
