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