mirror of
https://github.com/sheumann/hush.git
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455 lines
9.7 KiB
C
455 lines
9.7 KiB
C
/* vi: set sw=4 ts=4: */
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/*
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* Utility routines.
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*
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* Copyright (C) tons of folks. Tracking down who wrote what
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* isn't something I'm going to worry about... If you wrote something
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* here, please feel free to acknowledge your work.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*
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* Based in part on code from sash, Copyright (c) 1999 by David I. Bell
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* Permission has been granted to redistribute this code under the GPL.
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*
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*/
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#include <unistd.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include "busybox.h"
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#undef APPLET
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#undef APPLET_NOUSAGE
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#undef PROTOTYPES
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#include "applets.h"
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struct BB_applet *applet_using;
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/* The -1 arises because of the {0,NULL,0,-1} entry above. */
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const size_t NUM_APPLETS = (sizeof (applets) / sizeof (struct BB_applet) - 1);
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#ifdef CONFIG_FEATURE_SUID
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static void check_suid (struct BB_applet *app);
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#ifdef CONFIG_FEATURE_SUID_CONFIG
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#include <sys/stat.h>
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#include <ctype.h>
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#include "pwd_.h"
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#include "grp_.h"
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static int parse_config_file (void);
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static int config_ok;
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#define CONFIG_FILE "/etc/busybox.conf"
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/* applets [] is const, so we have to define this "override" structure */
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struct BB_suid_config
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{
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struct BB_applet *m_applet;
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uid_t m_uid;
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gid_t m_gid;
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mode_t m_mode;
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struct BB_suid_config *m_next;
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};
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static struct BB_suid_config *suid_config;
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#endif /* CONFIG_FEATURE_SUID_CONFIG */
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#endif /* CONFIG_FEATURE_SUID */
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extern void
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bb_show_usage (void)
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{
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const char *format_string;
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const char *usage_string = usage_messages;
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int i;
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for (i = applet_using - applets; i > 0;) {
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if (!*usage_string++) {
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--i;
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}
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}
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format_string = "%s\n\nUsage: %s %s\n\n";
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if (*usage_string == '\b')
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format_string = "%s\n\nNo help available.\n\n";
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fprintf (stderr, format_string, bb_msg_full_version, applet_using->name,
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usage_string);
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exit (EXIT_FAILURE);
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}
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static int
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applet_name_compare (const void *x, const void *y)
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{
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const char *name = x;
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const struct BB_applet *applet = y;
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return strcmp (name, applet->name);
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}
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extern const size_t NUM_APPLETS;
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struct BB_applet *
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find_applet_by_name (const char *name)
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{
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return bsearch (name, applets, NUM_APPLETS, sizeof (struct BB_applet),
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applet_name_compare);
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}
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void
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run_applet_by_name (const char *name, int argc, char **argv)
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{
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static int recurse_level = 0;
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extern int been_there_done_that; /* From busybox.c */
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#ifdef CONFIG_FEATURE_SUID_CONFIG
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if (recurse_level == 0)
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config_ok = parse_config_file ();
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#endif
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recurse_level++;
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/* Do a binary search to find the applet entry given the name. */
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if ((applet_using = find_applet_by_name (name)) != NULL) {
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bb_applet_name = applet_using->name;
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if (argv[1] && strcmp (argv[1], "--help") == 0) {
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if (strcmp (applet_using->name, "busybox") == 0) {
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if (argv[2])
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applet_using = find_applet_by_name (argv[2]);
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else
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applet_using = NULL;
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}
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if (applet_using)
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bb_show_usage ();
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been_there_done_that = 1;
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busybox_main (0, NULL);
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}
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#ifdef CONFIG_FEATURE_SUID
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check_suid (applet_using);
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#endif
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exit ((*(applet_using->main)) (argc, argv));
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}
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/* Just in case they have renamed busybox - Check argv[1] */
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if (recurse_level == 1) {
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run_applet_by_name ("busybox", argc, argv);
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}
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recurse_level--;
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}
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#ifdef CONFIG_FEATURE_SUID
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#ifdef CONFIG_FEATURE_SUID_CONFIG
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/* check if u is member of group g */
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static int
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ingroup (uid_t u, gid_t g)
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{
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struct group *grp = getgrgid (g);
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if (grp) {
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char **mem;
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for (mem = grp->gr_mem; *mem; mem++) {
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struct passwd *pwd = getpwnam (*mem);
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if (pwd && (pwd->pw_uid == u))
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return 1;
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}
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}
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return 0;
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}
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#endif
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void
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check_suid (struct BB_applet *applet)
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{
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uid_t ruid = getuid (); /* real [ug]id */
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uid_t rgid = getgid ();
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#ifdef CONFIG_FEATURE_SUID_CONFIG
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if (config_ok) {
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struct BB_suid_config *sct;
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for (sct = suid_config; sct; sct = sct->m_next) {
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if (sct->m_applet == applet)
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break;
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}
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if (sct) {
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mode_t m = sct->m_mode;
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if (sct->m_uid == ruid) /* same uid */
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m >>= 6;
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else if ((sct->m_gid == rgid) || ingroup (ruid, sct->m_gid)) /* same group / in group */
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m >>= 3;
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if (!(m & S_IXOTH)) /* is x bit not set ? */
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bb_error_msg_and_die ("You have no permission to run this applet!");
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if ((sct->m_mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) { /* *both* have to be set for sgid */
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if (setegid (sct->m_gid))
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bb_error_msg_and_die
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("BusyBox binary has insufficient rights to set proper GID for applet!");
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} else
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setgid (rgid); /* no sgid -> drop */
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if (sct->m_mode & S_ISUID) {
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if (seteuid (sct->m_uid))
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bb_error_msg_and_die
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("BusyBox binary has insufficient rights to set proper UID for applet!");
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} else
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setuid (ruid); /* no suid -> drop */
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} else {
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/* default: drop all priviledges */
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setgid (rgid);
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setuid (ruid);
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}
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return;
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} else {
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#ifndef CONFIG_FEATURE_SUID_CONFIG_QUIET
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static int onetime = 0;
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if (!onetime) {
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onetime = 1;
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fprintf (stderr, "Using fallback suid method\n");
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}
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#endif
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}
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#endif
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if (applet->need_suid == _BB_SUID_ALWAYS) {
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if (geteuid () != 0)
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bb_error_msg_and_die ("This applet requires root priviledges!");
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} else if (applet->need_suid == _BB_SUID_NEVER) {
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setgid (rgid); /* drop all priviledges */
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setuid (ruid);
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}
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}
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#ifdef CONFIG_FEATURE_SUID_CONFIG
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#define parse_error(x) { err=x; goto pe_label; }
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int
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parse_config_file (void)
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{
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struct stat st;
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char *err = 0;
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FILE *f = 0;
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int lc = 0;
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suid_config = 0;
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/* is there a config file ? */
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if (stat (CONFIG_FILE, &st) == 0) {
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/* is it owned by root with no write perm. for group and others ? */
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if (S_ISREG (st.st_mode) && (st.st_uid == 0)
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&& (!(st.st_mode & (S_IWGRP | S_IWOTH)))) {
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/* that's ok .. then try to open it */
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f = fopen (CONFIG_FILE, "r");
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if (f) {
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char buffer[256];
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int section = 0;
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while (fgets (buffer, sizeof (buffer) - 1, f)) {
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char c = buffer[0];
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char *p;
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lc++;
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p = strchr (buffer, '#');
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if (p)
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*p = 0;
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p = buffer + bb_strlen (buffer);
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while ((p > buffer) && isspace (*--p))
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*p = 0;
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if (p == buffer)
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continue;
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if (c == '[') {
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p = strchr (buffer, ']');
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if (!p || (p == (buffer + 1))) /* no matching ] or empty [] */
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parse_error ("malformed section header");
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*p = 0;
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if (strcasecmp (buffer + 1, "SUID") == 0)
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section = 1;
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else
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section = -1; /* unknown section - just skip */
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} else if (section) {
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switch (section) {
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case 1:{ /* SUID */
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int l;
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struct BB_applet *applet;
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p = strchr (buffer, '='); /* <key>[::space::]*=[::space::]*<value> */
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if (!p || (p == (buffer + 1))) /* no = or key is empty */
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parse_error ("malformed keyword");
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l = p - buffer;
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while (isspace (buffer[--l])) {
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/* skip whitespace */
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}
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buffer[l + 1] = 0;
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if ((applet = find_applet_by_name (buffer))) {
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struct BB_suid_config *sct =
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xmalloc (sizeof (struct BB_suid_config));
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sct->m_applet = applet;
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sct->m_next = suid_config;
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suid_config = sct;
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while (isspace (*++p)) {
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/* skip whitespace */
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}
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sct->m_mode = 0;
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switch (*p++) {
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case 'S':
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sct->m_mode |= S_ISUID;
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break;
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case 's':
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sct->m_mode |= S_ISUID;
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/* no break */
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case 'x':
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sct->m_mode |= S_IXUSR;
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break;
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case '-':
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break;
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default:
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parse_error ("invalid user mode");
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}
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switch (*p++) {
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case 's':
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sct->m_mode |= S_ISGID;
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/* no break */
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case 'x':
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sct->m_mode |= S_IXGRP;
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break;
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case 'S':
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break;
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case '-':
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break;
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default:
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parse_error ("invalid group mode");
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}
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switch (*p) {
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case 't':
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case 'x':
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sct->m_mode |= S_IXOTH;
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break;
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case 'T':
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case '-':
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break;
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default:
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parse_error ("invalid other mode");
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}
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while (isspace (*++p)) {
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/* skip whitespace */
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}
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if (isdigit (*p)) {
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sct->m_uid = strtol (p, &p, 10);
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if (*p++ != '.')
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parse_error ("parsing <uid>.<gid>");
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} else {
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struct passwd *pwd;
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char *p2 = strchr (p, '.');
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if (!p2)
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parse_error ("parsing <uid>.<gid>");
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*p2 = 0;
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pwd = getpwnam (p);
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if (!pwd)
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parse_error ("invalid user name");
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sct->m_uid = pwd->pw_uid;
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p = p2 + 1;
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}
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if (isdigit (*p))
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sct->m_gid = strtol (p, &p, 10);
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else {
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struct group *grp = getgrnam (p);
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if (!grp)
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parse_error ("invalid group name");
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sct->m_gid = grp->gr_gid;
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}
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}
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break;
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}
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default: /* unknown - skip */
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break;
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}
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} else
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parse_error ("keyword not within section");
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}
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fclose (f);
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return 1;
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}
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}
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}
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return 0; /* no config file or not readable (not an error) */
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pe_label:
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fprintf (stderr, "Parse error in %s, line %d: %s\n", CONFIG_FILE, lc, err);
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if (f)
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fclose (f);
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return 0;
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}
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#endif
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#endif
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/* END CODE */
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/*
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Local Variables:
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c-file-style: "linux"
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c-basic-offset: 4
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tab-width: 4
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End:
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*/
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