mirror of
https://github.com/sheumann/hush.git
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d1f8c1c125
and process... There still remains some stuff to clean up (the whole set_current_security_context() appears unnecessary complex to me), but this is now at least working.
482 lines
11 KiB
C
482 lines
11 KiB
C
/* vi: set sw=4 ts=4: */
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#include <fcntl.h>
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#include <signal.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 <syslog.h>
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#include <termios.h>
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#include <unistd.h>
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#include <utmp.h>
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#include <sys/resource.h>
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#include <sys/stat.h>
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#include <sys/time.h>
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#include <sys/types.h>
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#include <ctype.h>
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#include <time.h>
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#include "busybox.h"
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#ifdef CONFIG_SELINUX
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#include <selinux/selinux.h> /* for is_selinux_enabled() */
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#include <selinux/get_context_list.h> /* for get_default_context() */
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#include <selinux/flask.h> /* for security class definitions */
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#include <errno.h>
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#endif
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#ifdef CONFIG_FEATURE_UTMP
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// import from utmp.c
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static void checkutmp(int picky);
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static void setutmp(const char *name, const char *line);
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/* Stuff global to this file */
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static struct utmp utent;
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#endif
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// login defines
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#define TIMEOUT 60
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#define EMPTY_USERNAME_COUNT 10
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#define USERNAME_SIZE 32
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static int check_nologin ( int amroot );
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#if defined CONFIG_FEATURE_SECURETTY
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static int check_tty ( const char *tty );
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#else
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static inline int check_tty ( const char *tty ) { return 1; }
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#endif
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static int is_my_tty ( const char *tty );
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static int login_prompt ( char *buf_name );
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static void motd ( void );
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static void alarm_handler ( int sig ATTRIBUTE_UNUSED)
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{
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fprintf (stderr, "\nLogin timed out after %d seconds.\n", TIMEOUT );
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exit ( EXIT_SUCCESS );
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}
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int login_main(int argc, char **argv)
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{
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char tty[BUFSIZ];
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char full_tty[200];
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char fromhost[512];
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char username[USERNAME_SIZE];
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const char *tmp;
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int amroot;
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int flag;
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int failed;
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int count=0;
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struct passwd *pw, pw_copy;
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#ifdef CONFIG_WHEEL_GROUP
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struct group *grp;
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#endif
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int opt_preserve = 0;
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int opt_fflag = 0;
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char *opt_host = 0;
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int alarmstarted = 0;
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#ifdef CONFIG_SELINUX
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security_context_t user_sid = NULL;
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#endif
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username[0]=0;
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amroot = ( getuid ( ) == 0 );
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signal ( SIGALRM, alarm_handler );
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alarm ( TIMEOUT );
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alarmstarted = 1;
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while (( flag = getopt(argc, argv, "f:h:p")) != EOF ) {
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switch ( flag ) {
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case 'p':
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opt_preserve = 1;
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break;
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case 'f':
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/*
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* username must be a separate token
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* (-f root, *NOT* -froot). --marekm
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*/
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if ( optarg != argv[optind-1] )
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bb_show_usage( );
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if ( !amroot ) /* Auth bypass only if real UID is zero */
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bb_error_msg_and_die ( "-f permission denied" );
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safe_strncpy(username, optarg, USERNAME_SIZE);
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opt_fflag = 1;
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break;
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case 'h':
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opt_host = optarg;
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break;
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default:
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bb_show_usage( );
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}
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}
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if (optind < argc) // user from command line (getty)
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safe_strncpy(username, argv[optind], USERNAME_SIZE);
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if ( !isatty ( 0 ) || !isatty ( 1 ) || !isatty ( 2 ))
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return EXIT_FAILURE; /* Must be a terminal */
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#ifdef CONFIG_FEATURE_UTMP
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checkutmp ( !amroot );
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#endif
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tmp = ttyname ( 0 );
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if ( tmp && ( strncmp ( tmp, "/dev/", 5 ) == 0 ))
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safe_strncpy ( tty, tmp + 5, sizeof( tty ));
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else if ( tmp && *tmp == '/' )
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safe_strncpy ( tty, tmp, sizeof( tty ));
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else
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safe_strncpy ( tty, "UNKNOWN", sizeof( tty ));
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#ifdef CONFIG_FEATURE_UTMP
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if ( amroot )
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memset ( utent.ut_host, 0, sizeof utent.ut_host );
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#endif
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if ( opt_host ) {
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#ifdef CONFIG_FEATURE_UTMP
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safe_strncpy ( utent.ut_host, opt_host, sizeof( utent. ut_host ));
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#endif
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snprintf ( fromhost, sizeof( fromhost ) - 1, " on `%.100s' from `%.200s'", tty, opt_host );
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}
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else
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snprintf ( fromhost, sizeof( fromhost ) - 1, " on `%.100s'", tty );
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setpgrp();
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openlog ( "login", LOG_PID | LOG_CONS | LOG_NOWAIT, LOG_AUTH );
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while ( 1 ) {
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failed = 0;
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if ( !username[0] )
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if(!login_prompt ( username ))
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return EXIT_FAILURE;
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if ( !alarmstarted && ( TIMEOUT > 0 )) {
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alarm ( TIMEOUT );
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alarmstarted = 1;
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}
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if (!( pw = getpwnam ( username ))) {
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pw_copy.pw_name = "UNKNOWN";
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pw_copy.pw_passwd = "!";
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opt_fflag = 0;
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failed = 1;
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} else
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pw_copy = *pw;
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pw = &pw_copy;
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if (( pw-> pw_passwd [0] == '!' ) || ( pw-> pw_passwd[0] == '*' ))
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failed = 1;
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if ( opt_fflag ) {
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opt_fflag = 0;
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goto auth_ok;
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}
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if (!failed && ( pw-> pw_uid == 0 ) && ( !check_tty ( tty )))
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failed = 1;
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/* Don't check the password if password entry is empty (!) */
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if ( !pw-> pw_passwd[0] )
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goto auth_ok;
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/* authorization takes place here */
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if ( correct_password ( pw ))
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goto auth_ok;
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failed = 1;
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auth_ok:
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if ( !failed)
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break;
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bb_do_delay(FAIL_DELAY);
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puts("Login incorrect");
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username[0] = 0;
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if ( ++count == 3 ) {
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syslog ( LOG_WARNING, "invalid password for `%s'%s\n", pw->pw_name, fromhost);
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return EXIT_FAILURE;
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}
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}
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alarm ( 0 );
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if ( check_nologin ( pw-> pw_uid == 0 ))
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return EXIT_FAILURE;
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#ifdef CONFIG_FEATURE_UTMP
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setutmp ( username, tty );
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#endif
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if ( *tty != '/' )
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snprintf ( full_tty, sizeof( full_tty ) - 1, "/dev/%s", tty);
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else
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safe_strncpy ( full_tty, tty, sizeof( full_tty ) - 1 );
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#ifdef CONFIG_SELINUX
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if (is_selinux_enabled())
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{
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security_context_t old_tty_sid, new_tty_sid;
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if (get_default_context(username, NULL, &user_sid))
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{
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fprintf(stderr, "Unable to get SID for %s\n", username);
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exit(1);
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}
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if (getfilecon(full_tty, &old_tty_sid) < 0)
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{
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fprintf(stderr, "getfilecon(%.100s) failed: %.100s\n", full_tty, strerror(errno));
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return EXIT_FAILURE;
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}
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if (security_compute_relabel(user_sid, old_tty_sid, SECCLASS_CHR_FILE, &new_tty_sid) != 0)
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{
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fprintf(stderr, "security_change_sid(%.100s) failed: %.100s\n", full_tty, strerror(errno));
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return EXIT_FAILURE;
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}
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if(setfilecon(full_tty, new_tty_sid) != 0)
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{
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fprintf(stderr, "chsid(%.100s, %s) failed: %.100s\n", full_tty, new_tty_sid, strerror(errno));
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return EXIT_FAILURE;
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}
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}
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#endif
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if ( !is_my_tty ( full_tty ))
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syslog ( LOG_ERR, "unable to determine TTY name, got %s\n", full_tty );
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/* Try these, but don't complain if they fail
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* (for example when the root fs is read only) */
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chown ( full_tty, pw-> pw_uid, pw-> pw_gid );
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chmod ( full_tty, 0600 );
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change_identity ( pw );
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tmp = pw-> pw_shell;
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if(!tmp || !*tmp)
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tmp = DEFAULT_SHELL;
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setup_environment ( tmp, 1, !opt_preserve, pw );
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motd ( );
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signal ( SIGALRM, SIG_DFL ); /* default alarm signal */
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if ( pw-> pw_uid == 0 )
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syslog ( LOG_INFO, "root login %s\n", fromhost );
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#ifdef CONFIG_SELINUX
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/* well, a simple setexeccon() here would do the job as well,
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* but let's play the game for now */
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set_current_security_context(user_sid);
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#endif
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run_shell ( tmp, 1, 0, 0); /* exec the shell finally. */
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return EXIT_FAILURE;
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}
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static int login_prompt ( char *buf_name )
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{
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char buf [1024];
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char *sp, *ep;
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int i;
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for(i=0; i<EMPTY_USERNAME_COUNT; i++) {
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print_login_prompt();
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if ( !fgets ( buf, sizeof( buf ) - 1, stdin ))
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return 0;
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if ( !strchr ( buf, '\n' ))
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return 0;
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for ( sp = buf; isspace ( *sp ); sp++ ) { }
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for ( ep = sp; isgraph ( *ep ); ep++ ) { }
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*ep = 0;
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safe_strncpy(buf_name, sp, USERNAME_SIZE);
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if(buf_name[0])
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return 1;
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}
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return 0;
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}
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static int check_nologin ( int amroot )
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{
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if ( access ( bb_path_nologin_file, F_OK ) == 0 ) {
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FILE *fp;
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int c;
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if (( fp = fopen ( bb_path_nologin_file, "r" ))) {
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while (( c = getc ( fp )) != EOF )
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putchar (( c == '\n' ) ? '\r' : c );
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fflush ( stdout );
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fclose ( fp );
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} else {
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puts ( "\r\nSystem closed for routine maintenance.\r" );
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}
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if ( !amroot )
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return 1;
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puts ( "\r\n[Disconnect bypassed -- root login allowed.]\r" );
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}
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return 0;
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}
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#ifdef CONFIG_FEATURE_SECURETTY
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static int check_tty ( const char *tty )
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{
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FILE *fp;
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int i;
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char buf[BUFSIZ];
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if (( fp = fopen ( bb_path_securetty_file, "r" ))) {
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while ( fgets ( buf, sizeof( buf ) - 1, fp )) {
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for ( i = bb_strlen( buf ) - 1; i >= 0; --i ) {
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if ( !isspace ( buf[i] ))
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break;
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}
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buf[++i] = '\0';
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if (( buf [0] == '\0' ) || ( buf [0] == '#' ))
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continue;
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if ( strcmp ( buf, tty ) == 0 ) {
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fclose ( fp );
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return 1;
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}
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}
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fclose(fp);
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return 0;
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}
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/* A missing securetty file is not an error. */
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return 1;
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}
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#endif
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/* returns 1 if true */
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static int is_my_tty ( const char *tty )
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{
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struct stat by_name, by_fd;
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if ( stat ( tty, &by_name ) || fstat ( 0, &by_fd ))
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return 0;
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if ( by_name. st_rdev != by_fd. st_rdev )
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return 0;
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else
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return 1;
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}
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static void motd (void)
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{
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FILE *fp;
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register int c;
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if (( fp = fopen ( bb_path_motd_file, "r" ))) {
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while (( c = getc ( fp )) != EOF )
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putchar ( c );
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fclose ( fp );
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}
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}
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#ifdef CONFIG_FEATURE_UTMP
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// vv Taken from tinylogin utmp.c vv
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#define NO_UTENT \
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"No utmp entry. You must exec \"login\" from the lowest level \"sh\""
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#define NO_TTY \
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"Unable to determine your tty name."
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/*
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* checkutmp - see if utmp file is correct for this process
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*
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* System V is very picky about the contents of the utmp file
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* and requires that a slot for the current process exist.
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* The utmp file is scanned for an entry with the same process
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* ID. If no entry exists the process exits with a message.
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*
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* The "picky" flag is for network and other logins that may
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* use special flags. It allows the pid checks to be overridden.
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* This means that getty should never invoke login with any
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* command line flags.
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*/
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static void checkutmp(int picky)
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{
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char *line;
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struct utmp *ut;
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pid_t pid = getpid();
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setutent();
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/* First, try to find a valid utmp entry for this process. */
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while ((ut = getutent()))
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if (ut->ut_pid == pid && ut->ut_line[0] && ut->ut_id[0] &&
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(ut->ut_type == LOGIN_PROCESS || ut->ut_type == USER_PROCESS))
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break;
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/* If there is one, just use it, otherwise create a new one. */
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if (ut) {
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utent = *ut;
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} else {
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time_t t_tmp;
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if (picky) {
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puts(NO_UTENT);
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exit(1);
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}
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line = ttyname(0);
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if (!line) {
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puts(NO_TTY);
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exit(1);
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}
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if (strncmp(line, "/dev/", 5) == 0)
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line += 5;
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memset((void *) &utent, 0, sizeof utent);
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utent.ut_type = LOGIN_PROCESS;
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utent.ut_pid = pid;
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strncpy(utent.ut_line, line, sizeof utent.ut_line);
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/* XXX - assumes /dev/tty?? */
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strncpy(utent.ut_id, utent.ut_line + 3, sizeof utent.ut_id);
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strncpy(utent.ut_user, "LOGIN", sizeof utent.ut_user);
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t_tmp = (time_t)utent.ut_time;
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time(&t_tmp);
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}
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}
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/*
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* setutmp - put a USER_PROCESS entry in the utmp file
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*
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* setutmp changes the type of the current utmp entry to
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* USER_PROCESS. the wtmp file will be updated as well.
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*/
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static void setutmp(const char *name, const char *line ATTRIBUTE_UNUSED)
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{
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time_t t_tmp = (time_t)utent.ut_time;
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utent.ut_type = USER_PROCESS;
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strncpy(utent.ut_user, name, sizeof utent.ut_user);
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time(&t_tmp);
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/* other fields already filled in by checkutmp above */
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setutent();
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pututline(&utent);
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endutent();
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#ifdef CONFIG_FEATURE_WTMP
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if (access(_PATH_WTMP, R_OK|W_OK) == -1) {
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close(creat(_PATH_WTMP, 0664));
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}
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updwtmp(_PATH_WTMP, &utent);
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#endif
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}
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#endif /* CONFIG_FEATURE_UTMP */
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