Merge branch 'less_closed'

[unleashed.git] / usr / src / lib / libtsol / common / getpathbylabel.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */


/*
 *      Name:           getpathbylabel.c
 *
 *      Description:    Returns the global zone pathname corresponding
 *                      to the specified label. The pathname does
 *                      not need to match an existing file system object.
 *
 */
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <sys/types.h>
#include <tsol/label.h>
#include <stdlib.h>
#include <zone.h>
#include <sys/mntent.h>
#include <sys/mnttab.h>
#include <stdarg.h>

/*
 * This structure is used to chain mntent structures into a list
 * and to cache stat information for each member of the list.
 */
struct mntlist {
        struct mnttab   *mntl_mnt;
        struct mntlist  *mntl_next;
};


/*
 * Return a pointer to the trailing suffix of full that follows the prefix
 * given by pref.  If pref isn't a prefix of full, return NULL.  Apply
 * pathname semantics to the prefix test, so that pref must match at a
 * component boundary.
 */
static char *
pathsuffix(char *full, char *pref)
{
        int preflen;

        if (full == NULL || pref == NULL)
                return (NULL);

        preflen = strlen(pref);
        if (strncmp(pref, full, preflen) != 0)
                return (NULL);

        /*
         * pref is a substring of full.  To be a subpath, it cannot cover a
         * partial component of full.  The last clause of the test handles the
         * special case of the root.
         */
        if (full[preflen] != '\0' && full[preflen] != '/' && preflen > 1)
                return (NULL);

        if (preflen == 1 && full[0] == '/')
                return (full);
        else
                return (full + preflen);
}

/*
 * Return zero iff the path named by sub is a leading subpath
 * of the path named by full.
 *
 * Treat null paths as matching nothing.
 */
static int
subpath(char *full, char *sub)
{
        return (pathsuffix(full, sub) == NULL);
}

static void
tsol_mnt_free(struct mnttab *mnt)
{
        free(mnt->mnt_special);
        free(mnt->mnt_mountp);
        free(mnt->mnt_fstype);
        free(mnt->mnt_mntopts);
        free(mnt);
}

static void
tsol_mlist_free(struct mntlist *mlist)
{
        struct mntlist *mlp;
        struct mntlist *oldmlp;

        mlp = mlist;
        while (mlp) {
                struct mnttab *mnt = mlp->mntl_mnt;

                if (mnt)
                        tsol_mnt_free(mnt);
                oldmlp = mlp;
                mlp = mlp->mntl_next;
                free(oldmlp);
        }
}

static struct mnttab *
mntdup(struct mnttab *mnt)
{
        struct mnttab *new;

        new = (struct mnttab *)malloc(sizeof (*new));
        if (new == NULL)
                return (NULL);

        new->mnt_special = NULL;
        new->mnt_mountp = NULL;
        new->mnt_fstype = NULL;
        new->mnt_mntopts = NULL;

        new->mnt_special = strdup(mnt->mnt_special);
        if (new->mnt_special == NULL) {
                tsol_mnt_free(new);
                return (NULL);
        }
        new->mnt_mountp = strdup(mnt->mnt_mountp);
        if (new->mnt_mountp == NULL) {
                tsol_mnt_free(new);
                return (NULL);
        }
        new->mnt_fstype = strdup(mnt->mnt_fstype);
        if (new->mnt_fstype == NULL) {
                tsol_mnt_free(new);
                return (NULL);
        }
        new->mnt_mntopts = strdup(mnt->mnt_mntopts);
        if (new->mnt_mntopts == NULL) {
                tsol_mnt_free(new);
                return (NULL);
        }
        return (new);
}

static struct mntlist *
tsol_mkmntlist(void)
{
        FILE *mounted;
        struct mntlist *mntl;
        struct mntlist *mntst = NULL;
        struct mnttab mnt;

        if ((mounted = fopen(MNTTAB, "rF")) == NULL) {
                perror(MNTTAB);
                return (NULL);
        }
        resetmnttab(mounted);
        while (getmntent(mounted, &mnt) == NULL) {
                mntl = (struct mntlist *)malloc(sizeof (*mntl));
                if (mntl == NULL) {
                        tsol_mlist_free(mntst);
                        mntst = NULL;
                        break;
                }
                mntl->mntl_mnt = mntdup((struct mnttab *)(&mnt));
                if (mntl->mntl_mnt == NULL) {
                        tsol_mlist_free(mntst);
                        mntst = NULL;
                        break;
                }
                mntl->mntl_next = mntst;
                mntst = mntl;
        }
        (void) fclose(mounted);
        return (mntst);
}

/*
 * This function attempts to convert local zone NFS mounted pathnames
 * into equivalent global zone NFS mounted pathnames. At present
 * it only works for automounted filesystems. It depends on the
 * assumption that both the local and global zone automounters
 * share the same nameservices. It also assumes that any automount
 * map used by a local zone is available to the global zone automounter.
 *
 * The algorithm used consists of three phases.
 *
 * 1. The local zone's mnttab is searched to find the automount map
 *    with the closest matching mountpath.
 *
 * 2. The matching autmount map name is looked up in the global zone's
 *    mnttab to determine the path where it should be mounted in the
 *    global zone.
 *
 * 3. A pathname covered by an appropiate autofs trigger mount in
 *    the global zone is generated as the resolved pathname
 *
 * Among the things that can go wrong is that global zone doesn't have
 * a matching automount map or the mount was not done via the automounter.
 * Either of these cases return a NULL path.
 */
#define ZONE_OPT "zone="
static int
getnfspathbyautofs(struct mntlist *mlist, zoneid_t zoneid,
    struct mnttab *autofs_mnt, char *globalpath, char *zonepath, int global_len)
{
        struct mntlist *mlp;
        char zonematch[ZONENAME_MAX + 20];
        char zonename[ZONENAME_MAX];
        int  longestmatch;
        struct  mnttab  *mountmatch;

        if (autofs_mnt) {
                mountmatch = autofs_mnt;
                longestmatch = strlen(mountmatch->mnt_mountp);
        } else {
                /*
                 * First we need to get the zonename to look for
                 */
                if (zone_getattr(zoneid, ZONE_ATTR_NAME, zonename,
                    ZONENAME_MAX) == -1) {
                        return (0);
                }

                (void) strncpy(zonematch, ZONE_OPT, sizeof (zonematch));
                (void) strlcat(zonematch, zonename, sizeof (zonematch));

                /*
                 * Find the best match for an automount map that
                 * corresponds to the local zone's pathname
                 */
                longestmatch = 0;
                for (mlp = mlist; mlp; mlp = mlp->mntl_next) {
                        struct mnttab *mnt = mlp->mntl_mnt;
                        int     len;
                        int     matchfound;
                        char    *token;
                        char    *lasts;
                        char    mntopts[MAXPATHLEN];

                        if (subpath(globalpath, mnt->mnt_mountp) != 0)
                                continue;
                        if (strcmp(mnt->mnt_fstype, MNTTYPE_AUTOFS))
                                continue;

                        matchfound = 0;
                        (void) strncpy(mntopts, mnt->mnt_mntopts, MAXPATHLEN);
                        if ((token = strtok_r(mntopts, ",", &lasts)) != NULL) {
                                if (strcmp(token, zonematch) == 0) {
                                        matchfound = 1;
                                } else while ((token = strtok_r(NULL, ",",
                                    &lasts)) != NULL) {
                                        if (strcmp(token, zonematch) == 0) {
                                                matchfound = 1;
                                                break;
                                        }
                                }
                        }
                        if (matchfound) {
                                len = strlen(mnt->mnt_mountp);
                                if (len > longestmatch) {
                                        mountmatch = mnt;
                                        longestmatch = len;
                                }
                        }
                }
        }
        if (longestmatch == 0) {
                return (0);
        } else {
                /*
                 * Now we may have found the corresponding autofs mount
                 * Try to find the matching global zone autofs entry
                 */

                for (mlp = mlist; mlp; mlp = mlp->mntl_next) {
                        char p[MAXPATHLEN];
                        size_t zp_len;
                        size_t mp_len;

                        struct mnttab *mnt = mlp->mntl_mnt;

                        if (strcmp(mountmatch->mnt_special,
                            mnt->mnt_special) != 0)
                                continue;
                        if (strcmp(mnt->mnt_fstype, MNTTYPE_AUTOFS))
                                continue;
                        if (strstr(mnt->mnt_mntopts, ZONE_OPT) != NULL)
                                continue;
                        /*
                         * OK, we have a matching global zone automap
                         * so adjust the path for the global zone.
                         */
                        zp_len = strlen(zonepath);
                        mp_len = strlen(mnt->mnt_mountp);
                        (void) strncpy(p, globalpath + zp_len, MAXPATHLEN);
                        /*
                         * If both global zone and zone-relative
                         * mountpoint match, just use the same pathname
                         */
                        if (strncmp(mnt->mnt_mountp, p, mp_len) == 0) {
                                (void) strncpy(globalpath, p, global_len);
                                return (1);
                        } else {
                                (void) strncpy(p, globalpath, MAXPATHLEN);
                                (void) strncpy(globalpath, mnt->mnt_mountp,
                                    global_len);
                                (void) strlcat(globalpath,
                                    p + strlen(mountmatch->mnt_mountp),
                                    global_len);
                                return (1);
                        }
                }
                return (0);
        }
}

/*
 * Find the pathname for the entry in mlist that corresponds to the
 * file named by path (i.e., that names a mount table entry for the
 * file system in which path lies).
 *
 * Return 0 is there an error.
 */
static int
getglobalpath(const char *path, zoneid_t zoneid, struct mntlist *mlist,
    char *globalpath)
{
        struct mntlist *mlp;
        char            lofspath[MAXPATHLEN];
        char            zonepath[MAXPATHLEN];
        int             longestmatch;
        struct  mnttab  *mountmatch;

        if (zoneid != GLOBAL_ZONEID) {
                char    *prefix;

                if ((prefix = getzonerootbyid(zoneid)) == NULL) {
                        return (0);
                }
                (void) strncpy(zonepath, prefix, MAXPATHLEN);
                (void) strlcpy(globalpath, prefix, MAXPATHLEN);
                (void) strlcat(globalpath, path, MAXPATHLEN);
                free(prefix);
        } else {
                (void) strlcpy(globalpath, path, MAXPATHLEN);
        }

        for (;;) {
                longestmatch = 0;
                for (mlp = mlist; mlp; mlp = mlp->mntl_next) {
                        struct mnttab *mnt = mlp->mntl_mnt;
                        int     len;

                        if (subpath(globalpath, mnt->mnt_mountp) != 0)
                                continue;
                        len = strlen(mnt->mnt_mountp);
                        if (len > longestmatch) {
                                mountmatch = mnt;
                                longestmatch = len;
                        }
                }
                /*
                 * Handle interesting mounts.
                 */
                if ((strcmp(mountmatch->mnt_fstype, MNTTYPE_NFS) == 0) ||
                    (strcmp(mountmatch->mnt_fstype, MNTTYPE_AUTOFS) == 0)) {
                        if (zoneid > GLOBAL_ZONEID) {
                                struct mnttab *m = NULL;

                                if (strcmp(mountmatch->mnt_fstype,
                                    MNTTYPE_AUTOFS) == 0)
                                        m = mountmatch;
                                if (getnfspathbyautofs(mlist, zoneid, m,
                                    globalpath, zonepath, MAXPATHLEN) == 0) {
                                        return (0);
                                }
                        }
                        break;
                } else if (strcmp(mountmatch->mnt_fstype, MNTTYPE_LOFS) == 0) {
                        /*
                         * count up what's left
                         */
                        int     remainder;

                        remainder = strlen(globalpath) - longestmatch;
                        if (remainder > 0) {
                                path = pathsuffix(globalpath,
                                    mountmatch->mnt_mountp);
                                (void) strlcpy(lofspath, path, MAXPATHLEN);
                        }
                        (void) strlcpy(globalpath, mountmatch->mnt_special,
                            MAXPATHLEN);
                        if (remainder > 0) {
                                (void) strlcat(globalpath, lofspath,
                                    MAXPATHLEN);
                        }
                } else {
                        if ((zoneid > GLOBAL_ZONEID) &&
                            (strncmp(path, "/home/", strlen("/home/")) == 0)) {
                                char zonename[ZONENAME_MAX];

                                /*
                                 * If this is a cross-zone reference to
                                 * a home directory, it must be corrected.
                                 * We should only get here if the zone's
                                 * automounter hasn't yet mounted its
                                 * autofs trigger on /home.
                                 *
                                 * Since it is likely to do so in the
                                 * future, we will assume that the global
                                 * zone already has an equivalent autofs
                                 * mount established. By convention,
                                 * this should be mounted at the
                                 * /zone/<zonename>
                                 */

                                if (zone_getattr(zoneid, ZONE_ATTR_NAME,
                                    zonename, ZONENAME_MAX) == -1) {
                                        return (0);
                                } else {
                                        (void) snprintf(globalpath, MAXPATHLEN,
                                            "/zone/%s%s", zonename, path);
                                }
                        }
                        break;
                }
        }
        return (1);
}


/*
 * This function is only useful for global zone callers
 * It uses the global zone mnttab to translate local zone pathnames
 * into global zone pathnames.
 */
char *
getpathbylabel(const char *path_name, char *resolved_path, size_t bufsize,
    const bslabel_t *sl)
{
        char            ret_path[MAXPATHLEN];   /* pathname to return */
        zoneid_t        zoneid;
        struct mntlist *mlist;

        if (getzoneid() != GLOBAL_ZONEID) {
                errno = EINVAL;
                return (NULL);
        }

        if (path_name[0] != '/') {              /* need absolute pathname */
                errno = EINVAL;
                return (NULL);
        }

        if (resolved_path == NULL) {
                errno = EINVAL;
                return (NULL);
        }

        if ((zoneid = getzoneidbylabel(sl)) == -1)
                return (NULL);

        /*
         * Construct the list of mounted file systems.
         */

        if ((mlist = tsol_mkmntlist()) == NULL) {
                return (NULL);
        }
        if (getglobalpath(path_name, zoneid, mlist, ret_path) == 0) {
                tsol_mlist_free(mlist);
                return (NULL);
        }
        tsol_mlist_free(mlist);
        if (strlen(ret_path) >= bufsize) {
                errno = EFAULT;
                return (NULL);
        }
        return (strcpy(resolved_path, ret_path));
} /* end getpathbylabel() */