usr/src/sys/miscfs/umapfs/umap_subr.c

/*
 * Copyright (c) 1992, 1993, 1995
 *      The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software donated to Berkeley by
 * Jan-Simon Pendry.
 *
 * 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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 4. 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.
 *
 *      @(#)umap_subr.c 8.9 (Berkeley) 5/14/95
 *
 * From: $Id: lofs_subr.c, v 1.11 1992/05/30 10:05:43 jsp Exp jsp $
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/vnode.h>
#include <sys/mount.h>
#include <sys/namei.h>
#include <sys/malloc.h>
#include <miscfs/umapfs/umap.h>

#define LOG2_SIZEVNODE 7                /* log2(sizeof struct vnode) */
#define NUMAPNODECACHE 16

/*
 * Null layer cache:
 * Each cache entry holds a reference to the target vnode
 * along with a pointer to the alias vnode.  When an
 * entry is added the target vnode is VREF'd.  When the
 * alias is removed the target vnode is vrele'd.
 */

#define UMAP_NHASH(vp) \
        (&umap_node_hashtbl[(((u_long)vp)>>LOG2_SIZEVNODE) & umap_node_hash])
LIST_HEAD(umap_node_hashhead, umap_node) *umap_node_hashtbl;
u_long umap_node_hash;

/*
 * Initialise cache headers
 */
umapfs_init(vfsp)
        struct vfsconf *vfsp;
{

#ifdef UMAPFS_DIAGNOSTIC
        printf("umapfs_init\n");                /* printed during system boot */
#endif
        umap_node_hashtbl = hashinit(NUMAPNODECACHE, M_CACHE, &umap_node_hash);
}

/*
 * umap_findid is called by various routines in umap_vnodeops.c to
 * find a user or group id in a map.
 */
static u_long
umap_findid(id, map, nentries)
        u_long id;
        u_long map[][2];
        int nentries;
{
        int i;

        /* Find uid entry in map */
        i = 0;
        while ((i<nentries) && ((map[i][0]) != id))
                i++;

        if (i < nentries)
                return (map[i][1]);
        else
                return (-1);

}

/*
 * umap_reverse_findid is called by umap_getattr() in umap_vnodeops.c to
 * find a user or group id in a map, in reverse.
 */
u_long
umap_reverse_findid(id, map, nentries)
        u_long id;
        u_long map[][2];
        int nentries;
{
        int i;

        /* Find uid entry in map */
        i = 0;
        while ((i<nentries) && ((map[i][1]) != id))
                i++;

        if (i < nentries)
                return (map[i][0]);
        else
                return (-1);

}

/*
 * Return alias for target vnode if already exists, else 0.
 */
static struct vnode *
umap_node_find(mp, targetvp)
        struct mount *mp;
        struct vnode *targetvp;
{
        struct proc *p = curproc;               /* XXX */
        struct umap_node_hashhead *hd;
        struct umap_node *a;
        struct vnode *vp;

#ifdef UMAPFS_DIAGNOSTIC
        printf("umap_node_find(mp = %x, target = %x)\n", mp, targetvp);
#endif

        /*
         * Find hash base, and then search the (two-way) linked
         * list looking for a umap_node structure which is referencing
         * the target vnode.  If found, the increment the umap_node
         * reference count (but NOT the target vnode's VREF counter).
         */
        hd = UMAP_NHASH(targetvp);
loop:
        for (a = hd->lh_first; a != 0; a = a->umap_hash.le_next) {
                if (a->umap_lowervp == targetvp &&
                    a->umap_vnode->v_mount == mp) {
                        vp = UMAPTOV(a);
                        /*
                         * We need vget for the VXLOCK
                         * stuff, but we don't want to lock
                         * the lower node.
                         */
                        if (vget(vp, 0, p)) {
#ifdef UMAPFS_DIAGNOSTIC
                                printf ("umap_node_find: vget failed.\n");
#endif
                                goto loop;
                        }
                        return (vp);
                }
        }

#ifdef UMAPFS_DIAGNOSTIC
        printf("umap_node_find(%x, %x): NOT found\n", mp, targetvp);
#endif

        return (0);
}

/*
 * Make a new umap_node node.
 * Vp is the alias vnode, lofsvp is the target vnode.
 * Maintain a reference to (targetvp).
 */
static int
umap_node_alloc(mp, lowervp, vpp)
        struct mount *mp;
        struct vnode *lowervp;
        struct vnode **vpp;
{
        struct umap_node_hashhead *hd;
        struct umap_node *xp;
        struct vnode *othervp, *vp;
        int error;

        if (error = getnewvnode(VT_UMAP, mp, umap_vnodeop_p, vpp))
                return (error);
        vp = *vpp;

        MALLOC(xp, struct umap_node *, sizeof(struct umap_node),
            M_TEMP, M_WAITOK);
        vp->v_type = lowervp->v_type;
        xp->umap_vnode = vp;
        vp->v_data = xp;
        xp->umap_lowervp = lowervp;
        /*
         * Before we insert our new node onto the hash chains,
         * check to see if someone else has beaten us to it.
         * (We could have slept in MALLOC.)
         */
        if (othervp = umap_node_find(lowervp)) {
                FREE(xp, M_TEMP);
                vp->v_type = VBAD;      /* node is discarded */
                vp->v_usecount = 0;     /* XXX */
                *vpp = othervp;
                return (0);
        }
        VREF(lowervp);   /* Extra VREF will be vrele'd in umap_node_create */
        hd = UMAP_NHASH(lowervp);
        LIST_INSERT_HEAD(hd, xp, umap_hash);
        return (0);
}


/*
 * Try to find an existing umap_node vnode refering
 * to it, otherwise make a new umap_node vnode which
 * contains a reference to the target vnode.
 */
int
umap_node_create(mp, targetvp, newvpp)
        struct mount *mp;
        struct vnode *targetvp;
        struct vnode **newvpp;
{
        struct vnode *aliasvp;

        if (aliasvp = umap_node_find(mp, targetvp)) {
                /*
                 * Take another reference to the alias vnode
                 */
#ifdef UMAPFS_DIAGNOSTIC
                vprint("umap_node_create: exists", ap->umap_vnode);
#endif
                /* VREF(aliasvp); */
        } else {
                int error;

                /*
                 * Get new vnode.
                 */
#ifdef UMAPFS_DIAGNOSTIC
                printf("umap_node_create: create new alias vnode\n");
#endif
                /*
                 * Make new vnode reference the umap_node.
                 */
                if (error = umap_node_alloc(mp, targetvp, &aliasvp))
                        return (error);

                /*
                 * aliasvp is already VREF'd by getnewvnode()
                 */
        }

        vrele(targetvp);

#ifdef UMAPFS_DIAGNOSTIC
        vprint("umap_node_create: alias", aliasvp);
        vprint("umap_node_create: target", targetvp);
#endif

        *newvpp = aliasvp;
        return (0);
}

#ifdef UMAPFS_DIAGNOSTIC
int umap_checkvp_barrier = 1;
struct vnode *
umap_checkvp(vp, fil, lno)
        struct vnode *vp;
        char *fil;
        int lno;
{
        struct umap_node *a = VTOUMAP(vp);
#if 0
        /*
         * Can't do this check because vop_reclaim runs
         * with funny vop vector.
         */
        if (vp->v_op != umap_vnodeop_p) {
                printf ("umap_checkvp: on non-umap-node\n");
                while (umap_checkvp_barrier) /*WAIT*/ ;
                panic("umap_checkvp");
        }
#endif
        if (a->umap_lowervp == NULL) {
                /* Should never happen */
                int i; u_long *p;
                printf("vp = %x, ZERO ptr\n", vp);
                for (p = (u_long *) a, i = 0; i < 8; i++)
                        printf(" %x", p[i]);
                printf("\n");
                /* wait for debugger */
                while (umap_checkvp_barrier) /*WAIT*/ ;
                panic("umap_checkvp");
        }
        if (a->umap_lowervp->v_usecount < 1) {
                int i; u_long *p;
                printf("vp = %x, unref'ed lowervp\n", vp);
                for (p = (u_long *) a, i = 0; i < 8; i++)
                        printf(" %x", p[i]);
                printf("\n");
                /* wait for debugger */
                while (umap_checkvp_barrier) /*WAIT*/ ;
                panic ("umap with unref'ed lowervp");
        }
#if 0
        printf("umap %x/%d -> %x/%d [%s, %d]\n",
                a->umap_vnode, a->umap_vnode->v_usecount,
                a->umap_lowervp, a->umap_lowervp->v_usecount,
                fil, lno);
#endif
        return (a->umap_lowervp);
}
#endif

/* umap_mapids maps all of the ids in a credential, both user and group. */

void
umap_mapids(v_mount, credp)
        struct mount *v_mount;
        struct ucred *credp;
{
        int i, unentries, gnentries;
        u_long *groupmap, *usermap;
        uid_t uid;
        gid_t gid;

        unentries =  MOUNTTOUMAPMOUNT(v_mount)->info_nentries;
        usermap =  &(MOUNTTOUMAPMOUNT(v_mount)->info_mapdata[0][0]);
        gnentries =  MOUNTTOUMAPMOUNT(v_mount)->info_gnentries;
        groupmap =  &(MOUNTTOUMAPMOUNT(v_mount)->info_gmapdata[0][0]);

        /* Find uid entry in map */

        uid = (uid_t) umap_findid(credp->cr_uid, usermap, unentries);

        if (uid != -1)
                credp->cr_uid = uid;
        else
                credp->cr_uid = (uid_t) NOBODY;

#ifdef notdef
        /* cr_gid is the same as cr_groups[0] in 4BSD */

        /* Find gid entry in map */

        gid = (gid_t) umap_findid(credp->cr_gid, groupmap, gnentries);

        if (gid != -1)
                credp->cr_gid = gid;
        else
                credp->cr_gid = NULLGROUP;
#endif

        /* Now we must map each of the set of groups in the cr_groups
                structure. */

        i = 0;
        while (credp->cr_groups[i] != 0) {
                gid = (gid_t) umap_findid(credp->cr_groups[i],
                                        groupmap, gnentries);

                if (gid != -1)
                        credp->cr_groups[i++] = gid;
                else
                        credp->cr_groups[i++] = NULLGROUP;
        }
}