hal/hald/util_helper.c

/***************************************************************************
 *
 * util_helper.c - HAL utilities for helper (as e.g. prober/addons) et al.
 *
 * Copyright (C) 2006 David Zeuthen, <david@fubar.dk>
 *
 * Licensed under the Academic Free License version 2.1
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 *
 **************************************************************************/

#ifdef HAVE_CONFIG_H
#  include <config.h>
#endif

#include <grp.h>
#include <stdarg.h>
#include <stdlib.h>
#include <string.h>
#include <sys/time.h>
#include <time.h>
#include <pwd.h>
#include <unistd.h>

#include "logger.h"

#include "util_helper.h"

#ifdef __linux__
extern char **environ;
#endif

static char **argv_buffer = NULL;
static size_t argv_size = 0;

#ifdef sun
#include <priv.h>
void
drop_privileges(int keep_auxgroups)
{
    priv_set_t *pPrivSet;

    /*
     * Start with the 'basic' privilege set and then remove any
     * of the 'basic' privileges that will not be needed.
     */
    if ((pPrivSet = priv_allocset()) == NULL) {
        return;
    }

    /*
     * Establish the basic set of privileges.
     * Note: fork/exec required for libdevinfo devlink
     * interfaces are included in the basic set.
     */
    priv_basicset(pPrivSet);

    /* Clear privileges we will not need from the 'basic' set */
    (void) priv_delset(pPrivSet, PRIV_FILE_LINK_ANY);
    (void) priv_delset(pPrivSet, PRIV_PROC_INFO);
    (void) priv_delset(pPrivSet, PRIV_PROC_SESSION);

    /* for sysevent need to be root and have this privilege */
    (void) priv_addset(pPrivSet, PRIV_SYS_CONFIG);

    /* need proc_audit privilege */
    (void) priv_addset(pPrivSet, PRIV_PROC_AUDIT);

    /* Set the permitted privilege set. */
    (void) setppriv(PRIV_SET, PRIV_PERMITTED, pPrivSet);

    /* Set the limit privilege set. */
    (void) setppriv(PRIV_SET, PRIV_LIMIT, pPrivSet);

    priv_freeset(pPrivSet);
}
#else /* !sun */

/** Drop root privileges: Set the running user id to HAL_USER and
 *  group to HAL_GROUP, and optionally retain auxiliary groups of HAL_USER.
 */
void
drop_privileges (int keep_auxgroups)
{
    struct passwd *pw = NULL;
    struct group *gr = NULL;

    /* determine user id */
    pw = getpwnam (HAL_USER);
    if (!pw)  {
        HAL_DEBUG (("drop_privileges: user " HAL_USER " does not exist"));
        exit (-1);
    }

    /* determine primary group id */
    gr = getgrnam (HAL_GROUP);
    if (!gr) {
        HAL_DEBUG (("drop_privileges: group " HAL_GROUP " does not exist"));
        exit (-1);
    }

    if (keep_auxgroups) {
        if (initgroups (HAL_USER, gr->gr_gid)) {
            HAL_DEBUG(("drop_privileges: could not initialize groups"));
            exit (-1);
        }
    }

    if (setgid (gr->gr_gid)) {
        HAL_DEBUG (("drop_privileges: could not set group id"));
        exit (-1);
    }

    if (setuid (pw->pw_uid)) {
        HAL_DEBUG (("drop_privileges: could not set user id"));
        exit (-1);
    }
}
#endif /* !sun */

void
hal_set_proc_title_init (int argc, char *argv[])
{
#ifdef __linux__
    unsigned int i;
    char **new_environ, *endptr;

    /* This code is really really ugly. We make some memory layout
     * assumptions and reuse the environment array as memory to store
     * our process title in */

    for (i = 0; environ[i] != NULL; i++)
        ;

    endptr = i ? environ[i-1] + strlen (environ[i-1]) : argv[argc-1] + strlen (argv[argc-1]);

    argv_buffer = argv;
    argv_size = endptr - argv_buffer[0];

    /* Make a copy of environ */

    new_environ = malloc (sizeof(char*) * (i + 1));
    for (i = 0; environ[i] != NULL; i++)
        new_environ[i] = strdup (environ[i]);
    new_environ[i] = NULL;

    environ = new_environ;
#endif
}

/* this code borrowed from avahi-daemon's setproctitle.c (LGPL v2) */
void
hal_set_proc_title (const char *format, ...)
{
#ifdef __linux__
    size_t len;
    va_list ap;

    if (argv_buffer == NULL)
        goto out;

    va_start (ap, format);
    vsnprintf (argv_buffer[0], argv_size, format, ap);
    va_end (ap);

    len = strlen (argv_buffer[0]);

    memset (argv_buffer[0] + len, 0, argv_size - len);
    argv_buffer[1] = NULL;
out:
    ;
#endif
}