c9aca4561d
1) tinylogin like with compile time selection and a chown root.root 2) Runtime configurable via /etc/busybox.conf (docu is in the works) [Parts of this patch may overlap with my other two patches]
404 lines
9.8 KiB
C
404 lines
9.8 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 void parse_error ( int line, const char *err );
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static void parse_config_file ( void );
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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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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 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 == 0)
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format_string = "%s\n\nNo help available.\n\n";
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fprintf(stderr, format_string,
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full_version, applet_using->name, usage_string);
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exit(EXIT_FAILURE);
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}
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static int 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 *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 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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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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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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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 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 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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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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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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error_msg_and_die ( "BusyBox binary has insufficient rights to set proper GID for applet!" );
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}
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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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error_msg_and_die ( "BusyBox binary has insufficient rights to set proper UID for applet!" );
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}
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else
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setuid ( ruid ); // no suid -> drop
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}
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else { // default: drop all priviledges
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setgid ( rgid );
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setuid ( ruid );
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}
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#else
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if ( applet-> need_suid == _BB_SUID_ALWAYS ) {
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if ( geteuid ( ) != 0 )
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error_msg_and_die ( "This applet requires root priviledges!" );
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}
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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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#endif
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}
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#ifdef CONFIG_FEATURE_SUID_CONFIG
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void parse_error ( int line, const char *err )
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{
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char msg [512];
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snprintf ( msg, sizeof( msg ) - 1, "Parse error in %s, line %d: %s", CONFIG_FILE, line, err );
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error_msg_and_die ( msg );
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}
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void parse_config_file ( void )
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{
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struct stat st;
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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 ) && (!( st. st_mode & ( S_IWGRP | S_IWOTH )))) {
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// that's ok .. then try to open it
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FILE *f = fopen ( CONFIG_FILE, "r" );
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if ( f ) {
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char buffer [4096];
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int section = 0;
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int lc = 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 + xstrlen ( 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 ( lc, "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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}
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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 ( lc, "malformed keyword" );
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l = p - buffer;
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while ( isspace ( buffer [--l] )) { } // skip whitespace
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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 = 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 )) { } // skip whitespace
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sct-> m_mode = 0;
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switch ( *p++ ) {
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case 'S': sct-> m_mode |= S_ISUID; break;
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case 's': sct-> m_mode |= S_ISUID; // no break
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case 'x': sct-> m_mode |= S_IXUSR; break;
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case '-': break;
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default : parse_error ( lc, "invalid user mode" );
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}
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switch ( *p++ ) {
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case 's': sct-> m_mode |= S_ISGID; // no break
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case 'x': sct-> m_mode |= S_IXGRP; break;
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case 'S': break;
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case '-': break;
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default : parse_error ( lc, "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': sct-> m_mode |= S_IXOTH; break;
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case 'T':
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case '-': break;
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default : parse_error ( lc, "invalid other mode" );
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}
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while ( isspace ( *++p )) { } // skip whitespace
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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 ( lc, "parsing <uid>.<gid>" );
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}
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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 ( lc, "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 ( lc, "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 ( lc, "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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}
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else
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parse_error ( lc, "keyword not within section" );
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}
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fclose ( f );
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}
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}
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}
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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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