compat/common/getpwent.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 2009 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 *
 *  getpwent.c
 *
 * lib/nsswitch/compat/getpwent.c -- name-service-switch backend for getpwnam()
 *   et al that does 4.x compatibility.  It looks in /etc/passwd; if it finds
 *   passwd entries there that begin with "+" or "-", it consults other
 *   services.  By default it uses NIS (YP), but the user can override this
 *   with a "passwd_compat" entry in /etc/nsswitch.conf, e.g.
 *          passwd_compat: ldap
 *
 * This code tries to produce the same results as the 4.x code, even when
 *   the latter seems ill thought-out (mostly in the handling of netgroups,
 *   "-", and the combination thereof).  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.
 *    - Entries that begin with "+@" or "-@" are interpreted using
 *  getnetgrent() and innetgr(), which use the "netgroup" entry in
 *  /etc/nsswitch.conf.  If the sources for "passwd_compat" and "netgroup"
 *  differ, everything should work fine, but the semantics will be pretty
 *  confusing.
 */

#include <pwd.h>
#include <shadow.h>     /* For PASSWD (pathname to passwd file) */
#include <stdlib.h>
#include <strings.h>
#include "compat_common.h"

static DEFINE_NSS_DB_ROOT(db_root);

static void
_nss_initf_passwd_compat(p)
    nss_db_params_t *p;
{
    p->name       = NSS_DBNAM_PASSWD;
    p->config_name    = NSS_DBNAM_PASSWD_COMPAT;
    p->default_config = NSS_DEFCONF_PASSWD_COMPAT;
}

/*
 * Validates passwd entry replacing uid/gid > MAXUID by ID_NOBODY.
 */
int
validate_passwd_ids(char *line, int *linelenp, int buflen, int extra_chars)
{
    char    *linep, *limit, *uidp, *gidp;
    uid_t   uid;
    gid_t   gid;
    ulong_t uidl, gidl;
    int olduidlen, 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 username */
        continue;
    while (linep < limit && *linep++ != ':') /* skip password */
        continue;
    if (linep == limit)
        return (NSS_STR_PARSE_PARSE);

    uidp = linep;
    uidl = strtoul(uidp, (char **)&linep, 10); /* grab uid */
    olduidlen = linep - uidp;
    if (++linep >= limit || olduidlen == 0)
        return (NSS_STR_PARSE_PARSE);

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

    if (uidl <= MAXUID && gidl <= MAXUID)
        return (NSS_STR_PARSE_SUCCESS);
    uid = (uidl > MAXUID) ? UID_NOBODY : (uid_t)uidl;
    gid = (gidl > MAXUID) ? GID_NOBODY : (gid_t)gidl;

    /* Check if we have enough space in the buffer */
    idlen = snprintf(NULL, 0, "%u:%u", uid, gid);
    newlinelen = linelen + idlen - olduidlen - oldgidlen - 1;
    if (newlinelen + extra_chars > buflen)
        return (NSS_STR_PARSE_ERANGE);

    /* Replace ephemeral ids by ID_NOBODY */
    (void) bcopy(linep, uidp + idlen, limit - linep + extra_chars);
    (void) snprintf(uidp, idlen + 1, "%u:%u", uid, gid);
    *(uidp + idlen) = ':'; /* restore : that was overwritten by snprintf */
    *linelenp = newlinelen;
    return (NSS_STR_PARSE_SUCCESS);
}

static const char *
get_pwname(argp)
    nss_XbyY_args_t     *argp;
{
    struct passwd       *p = (struct passwd *)argp->returnval;

    return (p->pw_name);
}

static int
check_pwname(argp)
    nss_XbyY_args_t     *argp;
{
    struct passwd       *p = (struct passwd *)argp->returnval;

    return (strcmp(p->pw_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_pwname, NSS_DBOP_PASSWD_BYNAME));
}

static int
check_pwuid(argp)
    nss_XbyY_args_t     *argp;
{
    struct passwd       *p = (struct passwd *)argp->returnval;

    return (p->pw_uid == argp->key.uid);
}

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

    if (argp->key.uid > MAXUID)
        return (NSS_NOTFOUND);
    return (_nss_compat_XY_all(be, argp,
                check_pwuid, NSS_DBOP_PASSWD_BYUID));
}

/*ARGSUSED*/
static int
merge_pwents(be, argp, fields)
    compat_backend_ptr_t    be;
    nss_XbyY_args_t     *argp;
    const char      **fields;
{
    struct passwd       *pw = (struct passwd *)argp->buf.result;
    char            *buf    = malloc(NSS_LINELEN_PASSWD);
    char            *s;
    int         parsestat;
    int         len;
    int         buflen;

    if (buf == 0) {
        return (NSS_STR_PARSE_PARSE);
        /* Really "out of memory", but PARSE_PARSE will have to do */
    }
    /*
     * Don't allow overriding of
     *  - username
     *  - uid
     *  - gid
     * That's what the SunOS 4.x code did;  who are we to question it...
     */
    s = buf;
    buflen = argp->buf.buflen;

    if (fields[1] != 0)
        len = snprintf(s, buflen, "%s:%s",
                pw->pw_name, fields[1]);
    else {
/* ====> Does this do the right thing? */
        if (pw->pw_age != 0 && *pw->pw_age != '\0')
            len = snprintf(s, buflen, "%s:%s,%s",
                pw->pw_name, pw->pw_passwd, pw->pw_age);
        else
            len = snprintf(s, buflen, "%s:%s",
                pw->pw_name, pw->pw_passwd);
    }

    if (len > buflen)
        return (NSS_STR_PARSE_ERANGE);

    s += len;
    buflen -= len;
    len = snprintf(s, buflen, ":%u:%u:%s:%s:%s",
        pw->pw_uid,
        pw->pw_gid,
        fields[4] != 0 ? fields[4] : pw->pw_gecos,
        fields[5] != 0 ? fields[5] : pw->pw_dir,
        fields[6] != 0 ? fields[6] : pw->pw_shell);

    if (len > buflen)
        return (NSS_STR_PARSE_ERANGE);

    s += len;
    len = 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 (len > argp->buf.buflen) {
            parsestat = NSS_STR_PARSE_ERANGE;
        } else {
            (void) strncpy(argp->buf.buffer, buf, len);
            argp->returnval = argp->buf.buffer;
            argp->returnlen = len;
            parsestat = NSS_SUCCESS;
        }
    } else {
        parsestat = (*argp->str2ent)(buf, len,
                    argp->buf.result,
                    argp->buf.buffer,
                    argp->buf.buflen);
    }
    free(buf);
    return (parsestat);
}

static compat_backend_op_t passwd_ops[] = {
    _nss_compat_destr,
    _nss_compat_endent,
    _nss_compat_setent,
    _nss_compat_getent,
    getbyname,
    getbyuid
};

/*ARGSUSED*/
nss_backend_t *
_nss_compat_passwd_constr(dummy1, dummy2, dummy3)
    const char  *dummy1, *dummy2, *dummy3;
{
    return (_nss_compat_constr(passwd_ops,
                sizeof (passwd_ops) / sizeof (passwd_ops[0]),
                PASSWD,
                NSS_LINELEN_PASSWD,
                &db_root,
                _nss_initf_passwd_compat,
                1,
                get_pwname,
                merge_pwents));
}