X-Git-Url: https://git.librecmc.org/?a=blobdiff_plain;f=loginutils%2Flogin.c;h=3d8b8e540b0c7a39ac216b990964f3bee0c368d0;hb=24efe4f15fe45151681b41333f3713357ce8694b;hp=82be87eb366f45369d7e1a260dd4a60b06ad527b;hpb=942e4291fee9266dee2795e0f2628878b4f757e0;p=oweals%2Fbusybox.git diff --git a/loginutils/login.c b/loginutils/login.c index 82be87eb3..3d8b8e540 100644 --- a/loginutils/login.c +++ b/loginutils/login.c @@ -3,280 +3,358 @@ * Licensed under GPLv2 or later, see file LICENSE in this tarball for details. */ -#include -#include -#include -#include -#include -#include -#include -#include +#include "busybox.h" #include #include -#include -#include -#include -#include -#include +#include -#include "busybox.h" -#ifdef CONFIG_SELINUX +#if ENABLE_SELINUX #include /* for is_selinux_enabled() */ #include /* for get_default_context() */ #include /* for security class definitions */ #include #endif -#ifdef CONFIG_FEATURE_UTMP -// import from utmp.c -static void checkutmp(int picky); -static void setutmp(const char *name, const char *line); -/* Stuff global to this file */ -static struct utmp utent; -#endif - enum { TIMEOUT = 60, EMPTY_USERNAME_COUNT = 10, USERNAME_SIZE = 32, + TTYNAME_SIZE = 32, }; -static int check_nologin(int amroot); +static char* short_tty; + +#if ENABLE_FEATURE_UTMP +/* vv Taken from tinylogin utmp.c vv */ +/* + * read_or_build_utent - see if utmp file is correct for this process + * + * System V is very picky about the contents of the utmp file + * and requires that a slot for the current process exist. + * The utmp file is scanned for an entry with the same process + * ID. If no entry exists the process exits with a message. + * + * The "picky" flag is for network and other logins that may + * use special flags. It allows the pid checks to be overridden. + * This means that getty should never invoke login with any + * command line flags. + */ + +static void read_or_build_utent(struct utmp *utptr, int picky) +{ + struct utmp *ut; + pid_t pid = getpid(); -#if defined CONFIG_FEATURE_SECURETTY -static int check_tty(const char *tty); + setutent(); -#else -static inline int check_tty(const char *tty) { return 1; } + /* First, try to find a valid utmp entry for this process. */ + while ((ut = getutent())) + if (ut->ut_pid == pid && ut->ut_line[0] && ut->ut_id[0] && + (ut->ut_type == LOGIN_PROCESS || ut->ut_type == USER_PROCESS)) + break; + /* If there is one, just use it, otherwise create a new one. */ + if (ut) { + *utptr = *ut; + } else { + if (picky) + bb_error_msg_and_die("no utmp entry found"); + + memset(utptr, 0, sizeof(*utptr)); + utptr->ut_type = LOGIN_PROCESS; + utptr->ut_pid = pid; + strncpy(utptr->ut_line, short_tty, sizeof(utptr->ut_line)); + /* This one is only 4 chars wide. Try to fit something + * remotely meaningful by skipping "tty"... */ + strncpy(utptr->ut_id, short_tty + 3, sizeof(utptr->ut_id)); + strncpy(utptr->ut_user, "LOGIN", sizeof(utptr->ut_user)); + utptr->ut_time = time(NULL); + } + if (!picky) /* root login */ + memset(utptr->ut_host, 0, sizeof(utptr->ut_host)); +} + +/* + * write_utent - put a USER_PROCESS entry in the utmp file + * + * write_utent changes the type of the current utmp entry to + * USER_PROCESS. the wtmp file will be updated as well. + */ +static void write_utent(struct utmp *utptr, const char *username) +{ + utptr->ut_type = USER_PROCESS; + strncpy(utptr->ut_user, username, sizeof(utptr->ut_user)); + utptr->ut_time = time(NULL); + /* other fields already filled in by read_or_build_utent above */ + setutent(); + pututline(utptr); + endutent(); +#if ENABLE_FEATURE_WTMP + if (access(bb_path_wtmp_file, R_OK|W_OK) == -1) { + close(creat(bb_path_wtmp_file, 0664)); + } + updwtmp(bb_path_wtmp_file, utptr); #endif +} +#else /* !ENABLE_FEATURE_UTMP */ +#define read_or_build_utent(utptr, picky) ((void)0) +#define write_utent(utptr, username) ((void)0) +#endif /* !ENABLE_FEATURE_UTMP */ -static int is_my_tty(const char *tty); -static int login_prompt(char *buf_name); -static void motd(void); +static void die_if_nologin_and_non_root(int amroot) +{ + FILE *fp; + int c; + + if (access(bb_path_nologin_file, F_OK)) + return; + fp = fopen(bb_path_nologin_file, "r"); + if (fp) { + while ((c = getc(fp)) != EOF) + putchar((c=='\n') ? '\r' : c); + fflush(stdout); + fclose(fp); + } else + puts("\r\nSystem closed for routine maintenance\r"); + if (!amroot) + exit(1); + puts("\r\n[Disconnect bypassed -- root login allowed.]\r"); +} + +#if ENABLE_FEATURE_SECURETTY +static int check_securetty(void) +{ + FILE *fp; + int i; + char buf[BUFSIZ]; + + fp = fopen(bb_path_securetty_file, "r"); + if (!fp) { + /* A missing securetty file is not an error. */ + return 1; + } + while (fgets(buf, sizeof(buf)-1, fp)) { + for (i = strlen(buf)-1; i>=0; --i) { + if (!isspace(buf[i])) + break; + } + buf[++i] = '\0'; + if ((buf[0]=='\0') || (buf[0]=='#')) + continue; + if (strcmp(buf, short_tty) == 0) { + fclose(fp); + return 1; + } + } + fclose(fp); + return 0; +} +#else +static inline int check_securetty(void) { return 1; } +#endif + +static void get_username_or_die(char *buf, int size_buf) +{ + int c, cntdown; + cntdown = EMPTY_USERNAME_COUNT; +prompt: + /* skip whitespace */ + print_login_prompt(); + do { + c = getchar(); + if (c == EOF) exit(1); + if (c == '\n') { + if (!--cntdown) exit(1); + goto prompt; + } + } while (isspace(c)); + + *buf++ = c; + if (!fgets(buf, size_buf-2, stdin)) + exit(1); + if (!strchr(buf, '\n')) + exit(1); + while (isgraph(*buf)) buf++; + *buf = '\0'; +} + +static void motd(void) +{ + FILE *fp; + int c; + + fp = fopen(bb_path_motd_file, "r"); + if (fp) { + while ((c = getc(fp)) != EOF) + putchar(c); + fclose(fp); + } +} static void alarm_handler(int sig ATTRIBUTE_UNUSED) { - fprintf(stderr, "\nLogin timed out after %d seconds.\n", TIMEOUT); + /* This is the escape hatch! Poor serial line users and the like + * arrive here when their connection is broken. + * We don't want to block here */ + ndelay_on(1); + ndelay_on(2); + bb_info_msg("\r\nLogin timed out after %d seconds\r", TIMEOUT); exit(EXIT_SUCCESS); } - +int login_main(int argc, char **argv); int login_main(int argc, char **argv) { - char tty[BUFSIZ]; - char full_tty[200]; + enum { + LOGIN_OPT_f = (1<<0), + LOGIN_OPT_h = (1<<1), + LOGIN_OPT_p = (1<<2), + }; char fromhost[512]; char username[USERNAME_SIZE]; const char *tmp; int amroot; - int flag; - int failed; + unsigned opt; int count = 0; - struct passwd *pw, pw_copy; -#ifdef CONFIG_WHEEL_GROUP - struct group *grp; -#endif - int opt_preserve = 0; - int opt_fflag = 0; - char *opt_host = 0; - int alarmstarted = 0; -#ifdef CONFIG_SELINUX - security_context_t user_sid = NULL; -#endif - + struct passwd *pw; + char *opt_host = NULL; + char *opt_user = NULL; + char full_tty[TTYNAME_SIZE]; + USE_SELINUX(security_context_t user_sid = NULL;) + USE_FEATURE_UTMP(struct utmp utent;) + + short_tty = full_tty; username[0] = '\0'; amroot = (getuid() == 0); signal(SIGALRM, alarm_handler); alarm(TIMEOUT); - alarmstarted = 1; - while ((flag = getopt(argc, argv, "f:h:p")) != EOF) { - switch (flag) { - case 'p': - opt_preserve = 1; - break; - case 'f': - /* - * username must be a separate token - * (-f root, *NOT* -froot). --marekm - */ - if (optarg != argv[optind-1]) - bb_show_usage(); - - if (!amroot) /* Auth bypass only if real UID is zero */ - bb_error_msg_and_die("-f permission denied"); - - safe_strncpy(username, optarg, USERNAME_SIZE); - opt_fflag = 1; - break; - case 'h': - opt_host = optarg; - break; - default: - bb_show_usage(); - } + opt = getopt32(argc, argv, "f:h:p", &opt_user, &opt_host); + if (opt & LOGIN_OPT_f) { + if (!amroot) + bb_error_msg_and_die("-f is for root only"); + safe_strncpy(username, opt_user, sizeof(username)); } + if (optind < argc) /* user from command line (getty) */ + safe_strncpy(username, argv[optind], sizeof(username)); - if (optind < argc) /* user from command line (getty) */ - safe_strncpy(username, argv[optind], USERNAME_SIZE); - + /* Let's find out and memorize our tty */ if (!isatty(0) || !isatty(1) || !isatty(2)) return EXIT_FAILURE; /* Must be a terminal */ - -#ifdef CONFIG_FEATURE_UTMP - checkutmp(!amroot); -#endif - + safe_strncpy(full_tty, "UNKNOWN", sizeof(full_tty)); tmp = ttyname(0); - if (tmp && (strncmp(tmp, "/dev/", 5) == 0)) - safe_strncpy(tty, tmp + 5, sizeof(tty)); - else if (tmp && *tmp == '/') - safe_strncpy(tty, tmp, sizeof(tty)); - else - safe_strncpy(tty, "UNKNOWN", sizeof(tty)); - -#ifdef CONFIG_FEATURE_UTMP - if (amroot) - memset(utent.ut_host, 0, sizeof(utent.ut_host)); -#endif + if (tmp) { + safe_strncpy(full_tty, tmp, sizeof(full_tty)); + if (strncmp(full_tty, "/dev/", 5) == 0) + short_tty = full_tty + 5; + } + + read_or_build_utent(&utent, !amroot); if (opt_host) { -#ifdef CONFIG_FEATURE_UTMP - safe_strncpy(utent.ut_host, opt_host, sizeof(utent.ut_host)); -#endif - snprintf(fromhost, sizeof(fromhost)-1, " on `%.100s' from `%.200s'", tty, opt_host); - } - else - snprintf(fromhost, sizeof(fromhost)-1, " on `%.100s'", tty); + USE_FEATURE_UTMP( + safe_strncpy(utent.ut_host, opt_host, sizeof(utent.ut_host)); + ) + snprintf(fromhost, sizeof(fromhost)-1, " on '%.100s' from " + "'%.200s'", short_tty, opt_host); + } else + snprintf(fromhost, sizeof(fromhost)-1, " on '%.100s'", short_tty); bb_setpgrp; - openlog("login", LOG_PID | LOG_CONS | LOG_NOWAIT, LOG_AUTH); + openlog(applet_name, LOG_PID | LOG_CONS | LOG_NOWAIT, LOG_AUTH); while (1) { - failed = 0; - if (!username[0]) - if (!login_prompt(username)) - return EXIT_FAILURE; - - if (!alarmstarted && (TIMEOUT > 0)) { - alarm(TIMEOUT); - alarmstarted = 1; - } + get_username_or_die(username, sizeof(username)); pw = getpwnam(username); if (!pw) { - pw_copy.pw_name = "UNKNOWN"; - pw_copy.pw_passwd = "!"; - opt_fflag = 0; - failed = 1; - } else - pw_copy = *pw; + safe_strncpy(username, "UNKNOWN", sizeof(username)); + goto auth_failed; + } - pw = &pw_copy; + if (pw->pw_passwd[0] == '!' || pw->pw_passwd[0] == '*') + goto auth_failed; - if ((pw->pw_passwd[0] == '!') || (pw->pw_passwd[0] == '*')) - failed = 1; + if (opt & LOGIN_OPT_f) + break; /* -f USER: success without asking passwd */ - if (opt_fflag) { - opt_fflag = 0; - goto auth_ok; - } - - if (!failed && (pw->pw_uid == 0) && (!check_tty(tty))) - failed = 1; + if (pw->pw_uid == 0 && !check_securetty()) + goto auth_failed; /* Don't check the password if password entry is empty (!) */ if (!pw->pw_passwd[0]) - goto auth_ok; + break; /* authorization takes place here */ if (correct_password(pw)) - goto auth_ok; - - failed = 1; - -auth_ok: - if (!failed) break; +auth_failed: + opt &= ~LOGIN_OPT_f; bb_do_delay(FAIL_DELAY); puts("Login incorrect"); - username[0] = 0; if (++count == 3) { - syslog(LOG_WARNING, "invalid password for `%s'%s'\n", pw->pw_name, fromhost); + syslog(LOG_WARNING, "invalid password for '%s'%s", + username, fromhost); return EXIT_FAILURE; } + username[0] = '\0'; } alarm(0); - if (check_nologin(pw->pw_uid == 0)) - return EXIT_FAILURE; - -#ifdef CONFIG_FEATURE_UTMP - setutmp(username, tty); -#endif + die_if_nologin_and_non_root(pw->pw_uid == 0); - if (*tty != '/') - snprintf(full_tty, sizeof(full_tty)-1, "/dev/%s", tty); - else - safe_strncpy(full_tty, tty, sizeof(full_tty)-1); + write_utent(&utent, username); #ifdef CONFIG_SELINUX if (is_selinux_enabled()) { security_context_t old_tty_sid, new_tty_sid; if (get_default_context(username, NULL, &user_sid)) { - fprintf(stderr, "Unable to get SID for %s\n", username); - exit(1); + bb_error_msg_and_die("cannot get SID for %s", + username); } if (getfilecon(full_tty, &old_tty_sid) < 0) { - fprintf(stderr, "getfilecon(%.100s) failed: " - "%.100s\n", full_tty, strerror(errno)); - return EXIT_FAILURE; + bb_perror_msg_and_die("getfilecon(%s) failed", + full_tty); } - if (security_compute_relabel(user_sid, old_tty_sid, SECCLASS_CHR_FILE, - &new_tty_sid) != 0) { - fprintf(stderr, "security_change_sid(%.100s) failed: " - "%.100s\n", full_tty, strerror(errno)); - return EXIT_FAILURE; + if (security_compute_relabel(user_sid, old_tty_sid, + SECCLASS_CHR_FILE, &new_tty_sid) != 0) { + bb_perror_msg_and_die("security_change_sid(%s) failed", + full_tty); } if (setfilecon(full_tty, new_tty_sid) != 0) { - fprintf(stderr, "chsid(%.100s, %s) failed: " - "%.100s\n", full_tty, new_tty_sid, strerror(errno)); - return EXIT_FAILURE; + bb_perror_msg_and_die("chsid(%s, %s) failed", + full_tty, new_tty_sid); } } #endif - if (!is_my_tty(full_tty)) - syslog(LOG_ERR, "unable to determine TTY name, got %s\n", full_tty); - - /* Try these, but don't complain if they fail - * (for example when the root fs is read only) */ - chown(full_tty, pw->pw_uid, pw->pw_gid); - chmod(full_tty, 0600); + /* Try these, but don't complain if they fail. + * _f_chown is safe wrt race t=ttyname(0);...;chown(t); */ + fchown(0, pw->pw_uid, pw->pw_gid); + fchmod(0, 0600); if (ENABLE_LOGIN_SCRIPTS) { - char *script = getenv("LOGIN_PRE_SUID_SCRIPT"); - if (script) { - char *t_argv[2] = { script, NULL }; - switch (fork()) { - case -1: break; - case 0: /* child */ - xchdir("/"); - setenv("LOGIN_TTY", full_tty, 1); - setenv("LOGIN_USER", pw->pw_name, 1); - setenv("LOGIN_UID", utoa(pw->pw_uid), 1); - setenv("LOGIN_GID", utoa(pw->pw_gid), 1); - setenv("LOGIN_SHELL", pw->pw_shell, 1); - execvp(script, t_argv); - exit(1); - default: /* parent */ - wait(NULL); - } + char *t_argv[2]; + + t_argv[0] = getenv("LOGIN_PRE_SUID_SCRIPT"); + if (t_argv[0]) { + t_argv[1] = NULL; + setenv("LOGIN_TTY", full_tty, 1); + setenv("LOGIN_USER", pw->pw_name, 1); + setenv("LOGIN_UID", utoa(pw->pw_uid), 1); + setenv("LOGIN_GID", utoa(pw->pw_gid), 1); + setenv("LOGIN_SHELL", pw->pw_shell, 1); + xspawn(argv); /* NOMMU-friendly */ + unsetenv("LOGIN_TTY"); + unsetenv("LOGIN_USER"); + unsetenv("LOGIN_UID"); + unsetenv("LOGIN_GID"); + unsetenv("LOGIN_SHELL"); + wait(NULL); } } @@ -284,225 +362,35 @@ auth_ok: tmp = pw->pw_shell; if (!tmp || !*tmp) tmp = DEFAULT_SHELL; - setup_environment(tmp, 1, !opt_preserve, pw); + setup_environment(tmp, 1, !(opt & LOGIN_OPT_p), pw); motd(); - signal(SIGALRM, SIG_DFL); /* default alarm signal */ if (pw->pw_uid == 0) - syslog(LOG_INFO, "root login %s\n", fromhost); + syslog(LOG_INFO, "root login%s", fromhost); #ifdef CONFIG_SELINUX /* well, a simple setexeccon() here would do the job as well, * but let's play the game for now */ set_current_security_context(user_sid); #endif - run_shell(tmp, 1, 0, 0); /* exec the shell finally. */ - - return EXIT_FAILURE; -} - - -static int login_prompt(char *buf_name) -{ - char buf[1024]; - char *sp, *ep; - int i; - - for (i=0; i=0; --i) { - if (!isspace(buf[i])) - break; - } - buf[++i] = '\0'; - if ((buf[0]=='\0') || (buf[0]=='#')) - continue; - - if (strcmp(buf, tty)== 0) { - fclose(fp); - return 1; - } - } - fclose(fp); - return 0; - } - /* A missing securetty file is not an error. */ - return 1; -} - -#endif - -/* returns 1 if true */ -static int is_my_tty(const char *tty) -{ - struct stat by_name, by_fd; - - if (stat(tty, &by_name) || fstat(0, &by_fd)) - return 0; - - if (by_name.st_rdev != by_fd.st_rdev) - return 0; - else - return 1; -} - - -static void motd(void) -{ - FILE *fp; - int c; - - fp = fopen(bb_path_motd_file, "r"); - if (fp) { - while ((c = getc(fp)) != EOF) - putchar(c); - fclose(fp); - } -} - - -#ifdef CONFIG_FEATURE_UTMP -// vv Taken from tinylogin utmp.c vv - -#define NO_UTENT \ - "No utmp entry. You must exec \"login\" from the lowest level \"sh\"" -#define NO_TTY \ - "Unable to determine your tty name." - -/* - * checkutmp - see if utmp file is correct for this process - * - * System V is very picky about the contents of the utmp file - * and requires that a slot for the current process exist. - * The utmp file is scanned for an entry with the same process - * ID. If no entry exists the process exits with a message. - * - * The "picky" flag is for network and other logins that may - * use special flags. It allows the pid checks to be overridden. - * This means that getty should never invoke login with any - * command line flags. - */ - -static void checkutmp(int picky) -{ - char *line; - struct utmp *ut; - pid_t pid = getpid(); - - setutent(); - - /* First, try to find a valid utmp entry for this process. */ - while ((ut = getutent())) - if (ut->ut_pid == pid && ut->ut_line[0] && ut->ut_id[0] && - (ut->ut_type == LOGIN_PROCESS || ut->ut_type == USER_PROCESS)) - break; - - /* If there is one, just use it, otherwise create a new one. */ - if (ut) { - utent = *ut; - } else { - time_t t_tmp; - - if (picky) { - puts(NO_UTENT); - exit(1); - } - line = ttyname(0); - if (!line) { - puts(NO_TTY); - exit(1); - } - if (strncmp(line, "/dev/", 5) == 0) - line += 5; - memset(&utent, 0, sizeof(utent)); - utent.ut_type = LOGIN_PROCESS; - utent.ut_pid = pid; - strncpy(utent.ut_line, line, sizeof(utent.ut_line)); - /* XXX - assumes /dev/tty?? */ - strncpy(utent.ut_id, utent.ut_line + 3, sizeof(utent.ut_id)); - strncpy(utent.ut_user, "LOGIN", sizeof(utent.ut_user)); - t_tmp = (time_t)utent.ut_time; - time(&t_tmp); - } -} - -/* - * setutmp - put a USER_PROCESS entry in the utmp file - * - * setutmp changes the type of the current utmp entry to - * USER_PROCESS. the wtmp file will be updated as well. - */ - -static void setutmp(const char *name, const char *line ATTRIBUTE_UNUSED) -{ - time_t t_tmp = (time_t)utent.ut_time; - - utent.ut_type = USER_PROCESS; - strncpy(utent.ut_user, name, sizeof(utent.ut_user)); - time(&t_tmp); - /* other fields already filled in by checkutmp above */ - setutent(); - pututline(&utent); - endutent(); -#ifdef CONFIG_FEATURE_WTMP - if (access(bb_path_wtmp_file, R_OK|W_OK) == -1) { - close(creat(bb_path_wtmp_file, 0664)); - } - updwtmp(bb_path_wtmp_file, &utent); -#endif + return EXIT_FAILURE; } -#endif /* CONFIG_FEATURE_UTMP */