compat/common/getgrent.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
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/*
 *  getgrent.c
 *
 * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 *
 * lib/nsswitch/compat/getgrent.c -- name-service-switch backend for getgrnam()
 *   et al that does 4.x compatibility.  It looks in /etc/group; if it finds
 *   group entries there that begin with "+" or "-", it consults other
 *   services.  By default it uses NIS (YP), but the user can override this
 *   with a "group_compat" entry in /etc/nsswitch.conf, e.g.
 *          group_compat: ldap
 *
 * This code tries to produce the same results as the 4.x code, even when
 *   the latter seems ill thought-out.  Bug-compatible, in other words.
 *   Though we do try to be more reasonable about the format of "+" and "-"
 *   entries here, i.e. you don't have to pad them with spurious colons and
 *   bogus uid/gid values.
 *
 * Caveats:
 *    - More than one source may be specified, with the usual switch semantics,
 *  but having multiple sources here is definitely odd.
 *    - People who recursively specify "compat" deserve what they get.
 */

#include <grp.h>
#include <stdlib.h>
#include <unistd.h>     /* for GF_PATH */
#include <strings.h>
#include "compat_common.h"

static DEFINE_NSS_DB_ROOT(db_root);

static void
_nss_initf_group_compat(p)
    nss_db_params_t *p;
{
    p->name       = NSS_DBNAM_GROUP;
    p->config_name    = NSS_DBNAM_GROUP_COMPAT;
    p->default_config = NSS_DEFCONF_GROUP_COMPAT;
}

/*
 * Validates group entry replacing gid > MAXUID by GID_NOBODY.
 */
int
validate_group_ids(char *line, int *linelenp, int buflen, int extra_chars)
{
    char    *linep, *limit, *gidp;
    ulong_t gid;
    int oldgidlen, idlen;
    int linelen = *linelenp, newlinelen;

    if (linelen == 0 || *line == '+' || *line == '-')
        return (NSS_STR_PARSE_SUCCESS);

    linep = line;
    limit = line + linelen;

    while (linep < limit && *linep++ != ':') /* skip groupname */
        continue;
    while (linep < limit && *linep++ != ':') /* skip password */
        continue;
    if (linep == limit)
        return (NSS_STR_PARSE_PARSE);

    gidp = linep;
    gid = strtoul(gidp, (char **)&linep, 10); /* grab gid */
    oldgidlen = linep - gidp;
    if (linep >= limit || oldgidlen == 0)
        return (NSS_STR_PARSE_PARSE);

    if (gid <= MAXUID)
        return (NSS_STR_PARSE_SUCCESS);

    idlen = snprintf(NULL, 0, "%u", GID_NOBODY);
    newlinelen = linelen + idlen - oldgidlen;
    if (newlinelen + extra_chars > buflen)
        return (NSS_STR_PARSE_ERANGE);

    (void) bcopy(linep, gidp + idlen, limit - linep + extra_chars);
    (void) snprintf(gidp, idlen + 1, "%u", GID_NOBODY);
    *(gidp + idlen) = ':';
    *linelenp = newlinelen;
    return (NSS_STR_PARSE_SUCCESS);
}

static const char *
get_grname(argp)
    nss_XbyY_args_t     *argp;
{
    struct group        *g = (struct group *)argp->returnval;

    return (g->gr_name);
}

static int
check_grname(argp)
    nss_XbyY_args_t     *argp;
{
    struct group        *g = (struct group *)argp->returnval;

    return (strcmp(g->gr_name, argp->key.name) == 0);
}

static nss_status_t
getbyname(be, a)
    compat_backend_ptr_t    be;
    void            *a;
{
    nss_XbyY_args_t     *argp = (nss_XbyY_args_t *)a;

    return (_nss_compat_XY_all(be, argp, check_grname,
                NSS_DBOP_GROUP_BYNAME));
}

static int
check_grgid(argp)
    nss_XbyY_args_t     *argp;
{
    struct group        *g = (struct group *)argp->returnval;

    return (g->gr_gid == argp->key.gid);
}

static nss_status_t
getbygid(be, a)
    compat_backend_ptr_t    be;
    void            *a;
{
    nss_XbyY_args_t     *argp = (nss_XbyY_args_t *)a;

    if (argp->key.gid > MAXUID)
        return (NSS_NOTFOUND);
    return (_nss_compat_XY_all(be, argp, check_grgid,
                NSS_DBOP_GROUP_BYGID));
}

static nss_status_t
getbymember(be, a)
    compat_backend_ptr_t    be;
    void            *a;
{
    struct nss_groupsbymem  *argp = (struct nss_groupsbymem *)a;
    int         numgids = argp->numgids;
    int         maxgids = argp->maxgids;
    gid_t           *gid_array = argp->gid_array;
    struct nss_XbyY_args    grargs;
    struct group        *g;
    nss_XbyY_buf_t  *gb = NULL, *b = NULL;

    /*
     * Generic implementation:  enumerate using getent(), then check each
     *   group returned by getent() to see whether it contains the user.
     *   There are much faster ways, but at least this one gets the right
     *   answer.
     */
    if (numgids >= maxgids) {
        /* full gid_array;  nobody should have bothered to call us */
        return (NSS_SUCCESS);
    }

    b = NSS_XbyY_ALLOC(&gb, sizeof (struct group), NSS_BUFLEN_GROUP);
    if (b == 0)
        return (NSS_UNAVAIL);

    NSS_XbyY_INIT(&grargs, gb->result, gb->buffer, gb->buflen,
        argp->str2ent);
    g = (struct group *)gb->result;

    (void) _nss_compat_setent(be, 0);
    while (_nss_compat_getent(be, &grargs) == NSS_SUCCESS) {
        char        **mem;

        if (grargs.returnval == 0) {
            continue;
        }
        for (mem = g->gr_mem;  *mem != 0;  mem++) {
            if (strcmp(*mem, argp->username) == 0) {
                int gid = g->gr_gid;
                int i;
                for (i = 0;  i < numgids;  i++) {
                    if (gid == gid_array[i]) {
                        break;
                    }
                }
                if (i == numgids) {
                    gid_array[numgids++] = gid;
                    argp->numgids = numgids;
                    if (numgids >= maxgids) {
                        /* filled the gid_array */
                        (void) _nss_compat_endent(be,
                                0);
                        NSS_XbyY_FREE(&gb);
                        return (NSS_SUCCESS);
                    }
                    /* Done with this group, try next */
                    break;
                }
            }
        }
    }
    (void) _nss_compat_endent(be, 0);
    NSS_XbyY_FREE(&gb);
    return (NSS_NOTFOUND);  /* Really means "gid_array not full yet" */
}

/*ARGSUSED*/
static int
merge_grents(be, argp, fields)
    compat_backend_ptr_t    be;
    nss_XbyY_args_t     *argp;
    const char      **fields;
{
    struct group        *g  = (struct group *)argp->buf.result;
    char            *buf;
    char            *s;
    int         parsestat;
    int         dlen;

    /*
     * We're allowed to override the passwd (has anyone ever actually used
     *   the passwd in a group entry?) and the membership list, but not
     *   the groupname or the gid.
     * That's what the SunOS 4.x code did;  who are we to question it...
     *
     * Efficiency is heartlessly abandoned in the quest for simplicity.
     */
    if (fields[1] == 0 && fields[3] == 0 &&
            be->return_string_data != 1) {
        /* No legal overrides, leave *argp unscathed */
        return (NSS_STR_PARSE_SUCCESS);
    }
    if ((buf = malloc(NSS_LINELEN_GROUP)) == 0) {
        return (NSS_STR_PARSE_PARSE);
        /* Really "out of memory", but PARSE_PARSE will have to do */
    }
    s = buf;
    (void) snprintf(s, NSS_LINELEN_GROUP, "%s:%s:%u:",
        g->gr_name,
        fields[1] != 0 ? fields[1] : g->gr_passwd,
        g->gr_gid);
    s += strlen(s);
    if (fields[3] != 0) {
        (void) strcpy(s, fields[3]);
        s += strlen(s);
    } else {
        char    **memp;

        for (memp = g->gr_mem;  *memp != 0;  memp++) {
            size_t  len = strlen(*memp);
            if (s + len + 1 <= buf + NSS_LINELEN_GROUP) {
                if (memp != g->gr_mem) {
                    *s++ = ',';
                }
                (void) memcpy(s, *memp, len);
                s += len;
            } else {
                free(buf);
                return (NSS_STR_PARSE_ERANGE);
            }
        }
    }

    dlen = s - buf;

    /*
     * if asked, return the data in /etc file format
     */
    if (be->return_string_data == 1) {
        /* reset the result ptr to the original value */
        argp->buf.result = NULL;

        if (dlen > argp->buf.buflen) {
            parsestat = NSS_STR_PARSE_ERANGE;
        } else {
            (void) strncpy(argp->buf.buffer, buf, dlen);
            argp->returnval = argp->buf.buffer;
            argp->returnlen = dlen;
            parsestat = NSS_SUCCESS;
        }
    } else {
        parsestat = (*argp->str2ent)(buf, dlen,
                    argp->buf.result,
                    argp->buf.buffer,
                    argp->buf.buflen);
    }

    free(buf);
    return (parsestat);
}

static compat_backend_op_t group_ops[] = {
    _nss_compat_destr,
    _nss_compat_endent,
    _nss_compat_setent,
    _nss_compat_getent,
    getbyname,
    getbygid,
    getbymember
};

/*ARGSUSED*/
nss_backend_t *
_nss_compat_group_constr(dummy1, dummy2, dummy3)
    const char  *dummy1, *dummy2, *dummy3;
{
    return (_nss_compat_constr(group_ops,
                sizeof (group_ops) / sizeof (group_ops[0]),
                GF_PATH,
                NSS_LINELEN_GROUP,
                &db_root,
                _nss_initf_group_compat,
                0,
                get_grname,
                merge_grents));
}