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[netbsd-mini2440.git] / sys / kern / vfs_init.c

/*      $NetBSD: vfs_init.c,v 1.44 2009/05/03 21:25:44 elad Exp $       */

/*-
 * Copyright (c) 1998, 2000, 2008 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility,
 * NASA Ames Research Center.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

/*
 * Copyright (c) 1989, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed
 * to Berkeley by John Heidemann of the UCLA Ficus project.
 *
 * Source: * @(#)i405_init.c 2.10 92/04/27 UCLA Ficus project
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *      @(#)vfs_init.c  8.5 (Berkeley) 5/11/95
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: vfs_init.c,v 1.44 2009/05/03 21:25:44 elad Exp $");

#include <sys/param.h>
#include <sys/mount.h>
#include <sys/time.h>
#include <sys/vnode.h>
#include <sys/stat.h>
#include <sys/namei.h>
#include <sys/ucred.h>
#include <sys/buf.h>
#include <sys/errno.h>
#include <sys/kmem.h>
#include <sys/systm.h>
#include <sys/module.h>
#include <sys/dirhash.h>
#include <sys/sysctl.h>
#include <sys/kauth.h>

/*
 * Sigh, such primitive tools are these...
 */
#if 0
#define DODEBUG(A) A
#else
#define DODEBUG(A)
#endif

/*
 * The global list of vnode operations.
 */
extern const struct vnodeop_desc * const vfs_op_descs[];

/*
 * These vnodeopv_descs are listed here because they are not
 * associated with any particular file system, and thus cannot
 * be initialized by vfs_attach().
 */
extern const struct vnodeopv_desc dead_vnodeop_opv_desc;
extern const struct vnodeopv_desc fifo_vnodeop_opv_desc;
extern const struct vnodeopv_desc spec_vnodeop_opv_desc;
extern const struct vnodeopv_desc sync_vnodeop_opv_desc;

const struct vnodeopv_desc * const vfs_special_vnodeopv_descs[] = {
        &dead_vnodeop_opv_desc,
        &fifo_vnodeop_opv_desc,
        &spec_vnodeop_opv_desc,
        &sync_vnodeop_opv_desc,
        NULL,
};

struct vfs_list_head vfs_list =                 /* vfs list */
    LIST_HEAD_INITIALIZER(vfs_list);

static kauth_listener_t mount_listener;

/*
 * This code doesn't work if the defn is **vnodop_defns with cc.
 * The problem is because of the compiler sometimes putting in an
 * extra level of indirection for arrays.  It's an interesting
 * "feature" of C.
 */
typedef int (*PFI)(void *);

/*
 * A miscellaneous routine.
 * A generic "default" routine that just returns an error.
 */
/*ARGSUSED*/
int
vn_default_error(void *v)
{

        return (EOPNOTSUPP);
}

static struct sysctllog *vfs_sysctllog;

/*
 * Top level filesystem related information gathering.
 */
static void
sysctl_vfs_setup(void)
{
        extern int vfs_magiclinks;

        sysctl_createv(&vfs_sysctllog, 0, NULL, NULL,
                       CTLFLAG_PERMANENT,
                       CTLTYPE_NODE, "vfs", NULL,
                       NULL, 0, NULL, 0,
                       CTL_VFS, CTL_EOL);
        sysctl_createv(&vfs_sysctllog, 0, NULL, NULL,
                       CTLFLAG_PERMANENT,
                       CTLTYPE_NODE, "generic",
                       SYSCTL_DESCR("Non-specific vfs related information"),
                       NULL, 0, NULL, 0,
                       CTL_VFS, VFS_GENERIC, CTL_EOL);
        sysctl_createv(&vfs_sysctllog, 0, NULL, NULL,
                       CTLFLAG_PERMANENT,
                       CTLTYPE_STRING, "fstypes",
                       SYSCTL_DESCR("List of file systems present"),
                       sysctl_vfs_generic_fstypes, 0, NULL, 0,
                       CTL_VFS, VFS_GENERIC, CTL_CREATE, CTL_EOL);
        sysctl_createv(&vfs_sysctllog, 0, NULL, NULL,
                       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
                       CTLTYPE_INT, "magiclinks",
                       SYSCTL_DESCR("Whether \"magic\" symlinks are expanded"),
                       NULL, 0, &vfs_magiclinks, 0,
                       CTL_VFS, VFS_GENERIC, VFS_MAGICLINKS, CTL_EOL);
}


/*
 * vfs_init.c
 *
 * Allocate and fill in operations vectors.
 *
 * An undocumented feature of this approach to defining operations is that
 * there can be multiple entries in vfs_opv_descs for the same operations
 * vector. This allows third parties to extend the set of operations
 * supported by another layer in a binary compatibile way. For example,
 * assume that NFS needed to be modified to support Ficus. NFS has an entry
 * (probably nfs_vnopdeop_decls) declaring all the operations NFS supports by
 * default. Ficus could add another entry (ficus_nfs_vnodeop_decl_entensions)
 * listing those new operations Ficus adds to NFS, all without modifying the
 * NFS code. (Of couse, the OTW NFS protocol still needs to be munged, but
 * that is a(whole)nother story.) This is a feature.
 */

/*
 * Init the vector, if it needs it.
 * Also handle backwards compatibility.
 */
static void
vfs_opv_init_explicit(const struct vnodeopv_desc *vfs_opv_desc)
{
        int (**opv_desc_vector)(void *);
        const struct vnodeopv_entry_desc *opve_descp;

        opv_desc_vector = *(vfs_opv_desc->opv_desc_vector_p);

        for (opve_descp = vfs_opv_desc->opv_desc_ops;
             opve_descp->opve_op;
             opve_descp++) {
                /*
                 * Sanity check:  is this operation listed
                 * in the list of operations?  We check this
                 * by seeing if its offset is zero.  Since
                 * the default routine should always be listed
                 * first, it should be the only one with a zero
                 * offset.  Any other operation with a zero
                 * offset is probably not listed in
                 * vfs_op_descs, and so is probably an error.
                 *
                 * A panic here means the layer programmer
                 * has committed the all-too common bug
                 * of adding a new operation to the layer's
                 * list of vnode operations but
                 * not adding the operation to the system-wide
                 * list of supported operations.
                 */
                if (opve_descp->opve_op->vdesc_offset == 0 &&
                    opve_descp->opve_op->vdesc_offset != VOFFSET(vop_default)) {
                        printf("operation %s not listed in %s.\n",
                            opve_descp->opve_op->vdesc_name, "vfs_op_descs");
                        panic ("vfs_opv_init: bad operation");
                }

                /*
                 * Fill in this entry.
                 */
                opv_desc_vector[opve_descp->opve_op->vdesc_offset] =
                    opve_descp->opve_impl;
        }
}

static void
vfs_opv_init_default(const struct vnodeopv_desc *vfs_opv_desc)
{
        int j;
        int (**opv_desc_vector)(void *);

        opv_desc_vector = *(vfs_opv_desc->opv_desc_vector_p);

        /*
         * Force every operations vector to have a default routine.
         */
        if (opv_desc_vector[VOFFSET(vop_default)] == NULL)
                panic("vfs_opv_init: operation vector without default routine.");

        for (j = 0; j < VNODE_OPS_COUNT; j++)
                if (opv_desc_vector[j] == NULL)
                        opv_desc_vector[j] =
                            opv_desc_vector[VOFFSET(vop_default)];
}

void
vfs_opv_init(const struct vnodeopv_desc * const *vopvdpp)
{
        int (**opv_desc_vector)(void *);
        int i;

        /*
         * Allocate the vectors.
         */
        for (i = 0; vopvdpp[i] != NULL; i++) {
                opv_desc_vector =
                    kmem_alloc(VNODE_OPS_COUNT * sizeof(PFI), KM_SLEEP);
                memset(opv_desc_vector, 0, VNODE_OPS_COUNT * sizeof(PFI));
                *(vopvdpp[i]->opv_desc_vector_p) = opv_desc_vector;
                DODEBUG(printf("vector at %p allocated\n",
                    opv_desc_vector_p));
        }

        /*
         * ...and fill them in.
         */
        for (i = 0; vopvdpp[i] != NULL; i++)
                vfs_opv_init_explicit(vopvdpp[i]);

        /*
         * Finally, go back and replace unfilled routines
         * with their default.
         */
        for (i = 0; vopvdpp[i] != NULL; i++)
                vfs_opv_init_default(vopvdpp[i]);
}

void
vfs_opv_free(const struct vnodeopv_desc * const *vopvdpp)
{
        int i;

        /*
         * Free the vectors allocated in vfs_opv_init().
         */
        for (i = 0; vopvdpp[i] != NULL; i++) {
                kmem_free(*(vopvdpp[i]->opv_desc_vector_p),
                    VNODE_OPS_COUNT * sizeof(PFI));
                *(vopvdpp[i]->opv_desc_vector_p) = NULL;
        }
}

#ifdef DEBUG
static void
vfs_op_check(void)
{
        int i;

        DODEBUG(printf("Vnode_interface_init.\n"));

        /*
         * Check offset of each op.
         */
        for (i = 0; vfs_op_descs[i]; i++) {
                if (vfs_op_descs[i]->vdesc_offset != i)
                        panic("vfs_op_check: vfs_op_desc[] offset mismatch");
        }

        if (i != VNODE_OPS_COUNT) {
                panic("vfs_op_check: vnode ops count mismatch (%d != %d)",
                        i, VNODE_OPS_COUNT);
        }

        DODEBUG(printf ("vfs_opv_numops=%d\n", VNODE_OPS_COUNT));
}
#endif /* DEBUG */

/*
 * Common routine to check if an unprivileged mount is allowed.
 *
 * We export just this part (i.e., without the access control) so that if a
 * secmodel wants to implement finer grained user mounts it can do so without
 * copying too much code. More elaborate policies (i.e., specific users allowed
 * to also create devices and/or introduce set-id binaries, or export
 * file-systems) will require a different implementation.
 *
 * This routine is intended to be called from listener context, and as such
 * does not take credentials as an argument.
 */
int
usermount_common_policy(struct mount *mp, u_long flags)
{

        /* No exporting if unprivileged. */
        if (flags & MNT_EXPORTED)
                return EPERM;

        /* Must have 'nosuid' and 'nodev'. */
        if ((flags & MNT_NODEV) == 0 || (flags & MNT_NOSUID) == 0)
                return EPERM;

        /* Retain 'noexec'. */
        if ((mp->mnt_flag & MNT_NOEXEC) && (flags & MNT_NOEXEC) == 0)
                return EPERM;

        return 0;
}

static int
mount_listener_cb(kauth_cred_t cred, kauth_action_t action, void *cookie,
    void *arg0, void *arg1, void *arg2, void *arg3)
{
        int result;
        enum kauth_system_req req;

        result = KAUTH_RESULT_DEFER;
        req = (enum kauth_system_req)arg0;

        if ((action != KAUTH_SYSTEM_MOUNT) ||
            (req != KAUTH_REQ_SYSTEM_MOUNT_GET))
                return result;

        result = KAUTH_RESULT_ALLOW;

        return result;
}

/*
 * Initialize the vnode structures and initialize each file system type.
 */
void
vfsinit(void)
{

        /*
         * Attach sysctl nodes
         */
        sysctl_vfs_setup();

        /*
         * Initialize the namei pathname buffer pool and cache.
         */
        pnbuf_cache = pool_cache_init(MAXPATHLEN, 0, 0, 0, "pnbufpl",
            NULL, IPL_NONE, NULL, NULL, NULL);
        KASSERT(pnbuf_cache != NULL);

        /*
         * Initialize the vnode table
         */
        vntblinit();

        /*
         * Initialize the vnode name cache
         */
        nchinit();

#ifdef DEBUG
        /*
         * Check the list of vnode operations.
         */
        vfs_op_check();
#endif

        /*
         * Initialize the special vnode operations.
         */
        vfs_opv_init(vfs_special_vnodeopv_descs);

        /*
         * Initialise generic dirhash.
         */
        dirhash_init();

        /*
         * Initialise VFS hooks.
         */
        vfs_hooks_init();

        mount_listener = kauth_listen_scope(KAUTH_SCOPE_SYSTEM,
            mount_listener_cb, NULL);

        /*
         * Establish each file system which was statically
         * included in the kernel.
         */
        module_init_class(MODULE_CLASS_VFS);
}

/*
 * Drop a reference to a file system type.
 */
void
vfs_delref(struct vfsops *vfs)
{

        mutex_enter(&vfs_list_lock);
        vfs->vfs_refcount--;
        mutex_exit(&vfs_list_lock);
}

/*
 * Establish a file system and initialize it.
 */
int
vfs_attach(struct vfsops *vfs)
{
        struct vfsops *v;
        int error = 0;

        mutex_enter(&vfs_list_lock);

        /*
         * Make sure this file system doesn't already exist.
         */
        LIST_FOREACH(v, &vfs_list, vfs_list) {
                if (strcmp(vfs->vfs_name, v->vfs_name) == 0) {
                        error = EEXIST;
                        goto out;
                }
        }

        /*
         * Initialize the vnode operations for this file system.
         */
        vfs_opv_init(vfs->vfs_opv_descs);

        /*
         * Now initialize the file system itself.
         */
        (*vfs->vfs_init)();

        /*
         * ...and link it into the kernel's list.
         */
        LIST_INSERT_HEAD(&vfs_list, vfs, vfs_list);

        /*
         * Sanity: make sure the reference count is 0.
         */
        vfs->vfs_refcount = 0;
 out:
        mutex_exit(&vfs_list_lock);
        return (error);
}

/*
 * Remove a file system from the kernel.
 */
int
vfs_detach(struct vfsops *vfs)
{
        struct vfsops *v;
        int error = 0;

        mutex_enter(&vfs_list_lock);

        /*
         * Make sure no one is using the filesystem.
         */
        if (vfs->vfs_refcount != 0) {
                error = EBUSY;
                goto out;
        }

        /*
         * ...and remove it from the kernel's list.
         */
        LIST_FOREACH(v, &vfs_list, vfs_list) {
                if (v == vfs) {
                        LIST_REMOVE(v, vfs_list);
                        break;
                }
        }

        if (v == NULL) {
                error = ESRCH;
                goto out;
        }

        /*
         * Now run the file system-specific cleanups.
         */
        (*vfs->vfs_done)();

        /*
         * Free the vnode operations vector.
         */
        vfs_opv_free(vfs->vfs_opv_descs);
 out:
        mutex_exit(&vfs_list_lock);
        return (error);
}

void
vfs_reinit(void)
{
        struct vfsops *vfs;

        mutex_enter(&vfs_list_lock);
        LIST_FOREACH(vfs, &vfs_list, vfs_list) {
                if (vfs->vfs_reinit) {
                        vfs->vfs_refcount++;
                        mutex_exit(&vfs_list_lock);
                        (*vfs->vfs_reinit)();
                        mutex_enter(&vfs_list_lock);
                        vfs->vfs_refcount--;
                }
        }
        mutex_exit(&vfs_list_lock);
}