/* vi: set sw=4 ts=4: */
/*
- * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
+ * Licensed under GPLv2 or later, see file LICENSE in this source tree.
*/
+//usage:#define login_trivial_usage
+//usage: "[-p] [-h HOST] [[-f] USER]"
+//usage:#define login_full_usage "\n\n"
+//usage: "Begin a new session on the system\n"
+//usage: "\n -f Don't authenticate (user already authenticated)"
+//usage: "\n -h Name of the remote host"
+//usage: "\n -p Preserve environment"
+
#include "libbb.h"
#include <syslog.h>
-#include <utmp.h>
#include <sys/resource.h>
#if ENABLE_SELINUX
-#include <selinux/selinux.h> /* for is_selinux_enabled() */
-#include <selinux/get_context_list.h> /* for get_default_context() */
-#include <selinux/flask.h> /* for security class definitions */
+# include <selinux/selinux.h> /* for is_selinux_enabled() */
+# include <selinux/get_context_list.h> /* for get_default_context() */
+# include <selinux/flask.h> /* for security class definitions */
#endif
#if ENABLE_PAM
/* PAM may include <locale.h>. We may need to undefine bbox's stub define: */
-#undef setlocale
+# undef setlocale
/* For some obscure reason, PAM is not in pam/xxx, but in security/xxx.
* Apparently they like to confuse people. */
-#include <security/pam_appl.h>
-#include <security/pam_misc.h>
+# include <security/pam_appl.h>
+# include <security/pam_misc.h>
static const struct pam_conv conv = {
misc_conv,
NULL
enum {
TIMEOUT = 60,
EMPTY_USERNAME_COUNT = 10,
- USERNAME_SIZE = 32,
+ /* Some users found 32 chars limit to be too low: */
+ USERNAME_SIZE = 64,
TTYNAME_SIZE = 32,
};
-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();
+struct globals {
+ struct termios tty_attrs;
+} FIX_ALIASING;
+#define G (*(struct globals*)&bb_common_bufsiz1)
+#define INIT_G() do { } while (0)
- 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) {
- *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_tv.tv_sec = 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_tv.tv_sec = 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 */
#if ENABLE_FEATURE_NOLOGIN
static void die_if_nologin(void)
puts("\r\nSystem closed for routine maintenance\r");
fclose(fp);
- fflush(NULL);
+ fflush_all();
/* Users say that they do need this prior to exit: */
tcdrain(STDOUT_FILENO);
exit(EXIT_FAILURE);
}
#else
-static ALWAYS_INLINE void die_if_nologin(void) {}
+# define die_if_nologin() ((void)0)
#endif
#if ENABLE_FEATURE_SECURETTY && !ENABLE_PAM
-static int check_securetty(void)
+static int check_securetty(const char *short_tty)
{
char *buf = (char*)"/etc/securetty"; /* any non-NULL is ok */
parser_t *parser = config_open2("/etc/securetty", fopen_for_read);
return buf != NULL;
}
#else
-static ALWAYS_INLINE int check_securetty(void) { return 1; }
+static ALWAYS_INLINE int check_securetty(const char *short_tty UNUSED_PARAM) { return 1; }
#endif
+#if ENABLE_SELINUX
+static void initselinux(char *username, char *full_tty,
+ security_context_t *user_sid)
+{
+ security_context_t old_tty_sid, new_tty_sid;
+
+ if (!is_selinux_enabled())
+ return;
+
+ if (get_default_context(username, NULL, user_sid)) {
+ bb_error_msg_and_die("can't get SID for %s", username);
+ }
+ if (getfilecon(full_tty, &old_tty_sid) < 0) {
+ 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) {
+ bb_perror_msg_and_die("security_change_sid(%s) failed", full_tty);
+ }
+ if (setfilecon(full_tty, new_tty_sid) != 0) {
+ bb_perror_msg_and_die("chsid(%s, %s) failed", full_tty, new_tty_sid);
+ }
+}
+#endif
+
+#if ENABLE_LOGIN_SCRIPTS
+static void run_login_script(struct passwd *pw, char *full_tty)
+{
+ char *t_argv[2];
+
+ t_argv[0] = getenv("LOGIN_PRE_SUID_SCRIPT");
+ if (t_argv[0]) {
+ t_argv[1] = NULL;
+ xsetenv("LOGIN_TTY", full_tty);
+ xsetenv("LOGIN_USER", pw->pw_name);
+ xsetenv("LOGIN_UID", utoa(pw->pw_uid));
+ xsetenv("LOGIN_GID", utoa(pw->pw_gid));
+ xsetenv("LOGIN_SHELL", pw->pw_shell);
+ spawn_and_wait(t_argv); /* NOMMU-friendly */
+ unsetenv("LOGIN_TTY");
+ unsetenv("LOGIN_USER");
+ unsetenv("LOGIN_UID");
+ unsetenv("LOGIN_GID");
+ unsetenv("LOGIN_SHELL");
+ }
+}
+#else
+void run_login_script(struct passwd *pw, char *full_tty);
+#endif
+
+#if ENABLE_LOGIN_SESSION_AS_CHILD && ENABLE_PAM
+static void login_pam_end(pam_handle_t *pamh)
+{
+ int pamret;
+
+ pamret = pam_setcred(pamh, PAM_DELETE_CRED);
+ if (pamret != PAM_SUCCESS) {
+ bb_error_msg("pam_%s failed: %s (%d)", "setcred",
+ pam_strerror(pamh, pamret), pamret);
+ }
+ pamret = pam_close_session(pamh, 0);
+ if (pamret != PAM_SUCCESS) {
+ bb_error_msg("pam_%s failed: %s (%d)", "close_session",
+ pam_strerror(pamh, pamret), pamret);
+ }
+ pamret = pam_end(pamh, pamret);
+ if (pamret != PAM_SUCCESS) {
+ bb_error_msg("pam_%s failed: %s (%d)", "end",
+ pam_strerror(pamh, pamret), pamret);
+ }
+}
+#endif /* ENABLE_PAM */
+
static void get_username_or_die(char *buf, int size_buf)
{
int c, cntdown;
/* skip whitespace */
do {
c = getchar();
- if (c == EOF) exit(EXIT_FAILURE);
+ if (c == EOF)
+ exit(EXIT_FAILURE);
if (c == '\n') {
- if (!--cntdown) exit(EXIT_FAILURE);
+ if (!--cntdown)
+ exit(EXIT_FAILURE);
goto prompt;
}
- } while (isspace(c));
+ } while (isspace(c)); /* maybe isblank? */
*buf++ = c;
if (!fgets(buf, size_buf-2, stdin))
exit(EXIT_FAILURE);
if (!strchr(buf, '\n'))
exit(EXIT_FAILURE);
- while (isgraph(*buf)) buf++;
+ while ((unsigned char)*buf > ' ')
+ buf++;
*buf = '\0';
}
fd = open(bb_path_motd_file, O_RDONLY);
if (fd >= 0) {
- fflush(stdout);
+ fflush_all();
bb_copyfd_eof(fd, STDOUT_FILENO);
close(fd);
}
static void alarm_handler(int sig UNUSED_PARAM)
{
- /* This is the escape hatch! Poor serial line users and the like
+ /* 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);
- printf("\r\nLogin timed out after %d seconds\r\n", TIMEOUT);
- fflush(stdout);
+ ndelay_on(STDOUT_FILENO);
+ /* Test for correct attr restoring:
+ * run "getty 0 -" from a shell, enter bogus username, stop at
+ * password prompt, let it time out. Without the tcsetattr below,
+ * when you are back at shell prompt, echo will be still off.
+ */
+ tcsetattr_stdin_TCSANOW(&G.tty_attrs);
+ printf("\r\nLogin timed out after %u seconds\r\n", TIMEOUT);
+ fflush_all();
/* unix API is brain damaged regarding O_NONBLOCK,
* we should undo it, or else we can affect other processes */
- ndelay_off(1);
+ ndelay_off(STDOUT_FILENO);
_exit(EXIT_SUCCESS);
}
};
char *fromhost;
char username[USERNAME_SIZE];
- const char *tmp;
- int amroot;
+ int run_by_root;
unsigned opt;
int count = 0;
struct passwd *pw;
- char *opt_host = opt_host; /* for compiler */
+ char *opt_host = NULL;
char *opt_user = opt_user; /* for compiler */
- char full_tty[TTYNAME_SIZE];
- USE_SELINUX(security_context_t user_sid = NULL;)
- USE_FEATURE_UTMP(struct utmp utent;)
+ char *full_tty;
+ char *short_tty;
+ IF_SELINUX(security_context_t user_sid = NULL;)
#if ENABLE_PAM
int pamret;
pam_handle_t *pamh;
const char *failed_msg;
struct passwd pwdstruct;
char pwdbuf[256];
+ char **pamenv;
+#endif
+#if ENABLE_LOGIN_SESSION_AS_CHILD
+ pid_t child_pid;
#endif
- short_tty = full_tty;
- username[0] = '\0';
- signal(SIGALRM, alarm_handler);
- alarm(TIMEOUT);
+ INIT_G();
- /* More of suid paranoia if called by non-root */
- amroot = !sanitize_env_if_suid(); /* Clear dangerous stuff, set PATH */
+ /* More of suid paranoia if called by non-root: */
+ /* Clear dangerous stuff, set PATH */
+ run_by_root = !sanitize_env_if_suid();
/* Mandatory paranoia for suid applet:
* ensure that fd# 0,1,2 are opened (at least to /dev/null)
* (The name of the function is misleading. Not daemonizing here.) */
bb_daemonize_or_rexec(DAEMON_ONLY_SANITIZE | DAEMON_CLOSE_EXTRA_FDS, NULL);
+ username[0] = '\0';
opt = getopt32(argv, "f:h:p", &opt_user, &opt_host);
if (opt & LOGIN_OPT_f) {
- if (!amroot)
+ if (!run_by_root)
bb_error_msg_and_die("-f is for root only");
safe_strncpy(username, opt_user, sizeof(username));
}
if (argv[0]) /* user from command line (getty) */
safe_strncpy(username, argv[0], sizeof(username));
- /* Let's find out and memorize our tty */
- if (!isatty(0) || !isatty(1) || !isatty(2))
- return EXIT_FAILURE; /* Must be a terminal */
- safe_strncpy(full_tty, "UNKNOWN", sizeof(full_tty));
- tmp = ttyname(0);
- if (tmp) {
- safe_strncpy(full_tty, tmp, sizeof(full_tty));
- if (strncmp(full_tty, "/dev/", 5) == 0)
- short_tty = full_tty + 5;
+ /* Save tty attributes - and by doing it, check that it's indeed a tty */
+ if (tcgetattr(STDIN_FILENO, &G.tty_attrs) < 0
+ || !isatty(STDOUT_FILENO)
+ /*|| !isatty(STDERR_FILENO) - no, guess some people might want to redirect this */
+ ) {
+ return EXIT_FAILURE; /* Must be a terminal */
}
- read_or_build_utent(&utent, !amroot);
+ /* We install timeout handler only _after_ we saved G.tty_attrs */
+ signal(SIGALRM, alarm_handler);
+ alarm(TIMEOUT);
+
+ /* Find out and memorize our tty name */
+ full_tty = xmalloc_ttyname(STDIN_FILENO);
+ if (!full_tty)
+ full_tty = xstrdup("UNKNOWN");
+ short_tty = skip_dev_pfx(full_tty);
- if (opt & LOGIN_OPT_h) {
- USE_FEATURE_UTMP(
- safe_strncpy(utent.ut_host, opt_host, sizeof(utent.ut_host));
- )
+ if (opt_host) {
fromhost = xasprintf(" on '%s' from '%s'", short_tty, opt_host);
- } else
+ } else {
fromhost = xasprintf(" on '%s'", short_tty);
+ }
/* Was breaking "login <username>" from shell command line: */
/*bb_setpgrp();*/
- openlog(applet_name, LOG_PID | LOG_CONS | LOG_NOWAIT, LOG_AUTH);
+ openlog(applet_name, LOG_PID | LOG_CONS, LOG_AUTH);
while (1) {
/* flush away any type-ahead (as getty does) */
- ioctl(0, TCFLSH, TCIFLUSH);
+ tcflush(0, TCIFLUSH);
if (!username[0])
get_username_or_die(username, sizeof(username));
failed_msg = "set_item(TTY)";
goto pam_auth_failed;
}
- pamret = pam_authenticate(pamh, 0);
- if (pamret != PAM_SUCCESS) {
- failed_msg = "authenticate";
- goto pam_auth_failed;
- /* TODO: or just "goto auth_failed"
- * since user seems to enter wrong password
- * (in this case pamret == 7)
- */
+ /* set RHOST */
+ if (opt_host) {
+ pamret = pam_set_item(pamh, PAM_RHOST, opt_host);
+ if (pamret != PAM_SUCCESS) {
+ failed_msg = "set_item(RHOST)";
+ goto pam_auth_failed;
+ }
+ }
+ if (!(opt & LOGIN_OPT_f)) {
+ pamret = pam_authenticate(pamh, 0);
+ if (pamret != PAM_SUCCESS) {
+ failed_msg = "authenticate";
+ goto pam_auth_failed;
+ /* TODO: or just "goto auth_failed"
+ * since user seems to enter wrong password
+ * (in this case pamret == 7)
+ */
+ }
}
/* check that the account is healthy */
pamret = pam_acct_mgmt(pamh, 0);
break; /* success, continue login process */
pam_auth_failed:
- bb_error_msg("pam_%s call failed: %s (%d)", failed_msg,
+ /* syslog, because we don't want potential attacker
+ * to know _why_ login failed */
+ syslog(LOG_WARNING, "pam_%s call failed: %s (%d)", failed_msg,
pam_strerror(pamh, pamret), pamret);
safe_strncpy(username, "UNKNOWN", sizeof(username));
#else /* not PAM */
if (opt & LOGIN_OPT_f)
break; /* -f USER: success without asking passwd */
- if (pw->pw_uid == 0 && !check_securetty())
+ if (pw->pw_uid == 0 && !check_securetty(short_tty))
goto auth_failed;
/* Don't check the password if password entry is empty (!) */
if (!pw->pw_passwd[0])
break;
fake_it:
- /* authorization takes place here */
- if (correct_password(pw))
+ /* Password reading and authorization takes place here.
+ * Note that reads (in no-echo mode) trash tty attributes.
+ * If we get interrupted by SIGALRM, we need to restore attrs.
+ */
+ if (ask_and_check_password(pw) > 0)
break;
#endif /* ENABLE_PAM */
auth_failed:
opt &= ~LOGIN_OPT_f;
- bb_do_delay(FAIL_DELAY);
+ bb_do_delay(LOGIN_FAIL_DELAY);
/* TODO: doesn't sound like correct English phrase to me */
puts("Login incorrect");
if (++count == 3) {
syslog(LOG_WARNING, "invalid password for '%s'%s",
username, fromhost);
+
+ if (ENABLE_FEATURE_CLEAN_UP)
+ free(fromhost);
+
return EXIT_FAILURE;
}
username[0] = '\0';
- }
+ } /* while (1) */
alarm(0);
- if (!amroot)
+ /* We can ignore /etc/nologin if we are logging in as root,
+ * it doesn't matter whether we are run by root or not */
+ if (pw->pw_uid != 0)
die_if_nologin();
- write_utent(&utent, username);
-
-#if ENABLE_SELINUX
- if (is_selinux_enabled()) {
- security_context_t old_tty_sid, new_tty_sid;
-
- if (get_default_context(username, NULL, &user_sid)) {
- bb_error_msg_and_die("cannot get SID for %s",
- username);
- }
- if (getfilecon(full_tty, &old_tty_sid) < 0) {
- 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) {
- bb_perror_msg_and_die("security_change_sid(%s) failed",
- full_tty);
- }
- if (setfilecon(full_tty, new_tty_sid) != 0) {
- bb_perror_msg_and_die("chsid(%s, %s) failed",
- full_tty, new_tty_sid);
+#if ENABLE_LOGIN_SESSION_AS_CHILD
+ child_pid = vfork();
+ if (child_pid != 0) {
+ if (child_pid < 0)
+ bb_perror_msg("vfork");
+ else {
+ if (safe_waitpid(child_pid, NULL, 0) == -1)
+ bb_perror_msg("waitpid");
+ update_utmp_DEAD_PROCESS(child_pid);
}
+ IF_PAM(login_pam_end(pamh);)
+ return 0;
}
#endif
+
+ IF_SELINUX(initselinux(username, full_tty, &user_sid);)
+
/* 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);
+ update_utmp(getpid(), USER_PROCESS, short_tty, username, run_by_root ? opt_host : NULL);
+
/* We trust environment only if we run by root */
- if (ENABLE_LOGIN_SCRIPTS && amroot) {
- char *t_argv[2];
-
- t_argv[0] = getenv("LOGIN_PRE_SUID_SCRIPT");
- if (t_argv[0]) {
- t_argv[1] = NULL;
- xsetenv("LOGIN_TTY", full_tty);
- xsetenv("LOGIN_USER", pw->pw_name);
- xsetenv("LOGIN_UID", utoa(pw->pw_uid));
- xsetenv("LOGIN_GID", utoa(pw->pw_gid));
- xsetenv("LOGIN_SHELL", pw->pw_shell);
- spawn_and_wait(t_argv); /* NOMMU-friendly */
- unsetenv("LOGIN_TTY" );
- unsetenv("LOGIN_USER" );
- unsetenv("LOGIN_UID" );
- unsetenv("LOGIN_GID" );
- unsetenv("LOGIN_SHELL");
- }
- }
+ if (ENABLE_LOGIN_SCRIPTS && run_by_root)
+ run_login_script(pw, full_tty);
change_identity(pw);
- tmp = pw->pw_shell;
- if (!tmp || !*tmp)
- tmp = DEFAULT_SHELL;
- /* setup_environment params: shell, clear_env, change_env, pw */
- setup_environment(tmp, !(opt & LOGIN_OPT_p), 1, pw);
+ setup_environment(pw->pw_shell,
+ (!(opt & LOGIN_OPT_p) * SETUP_ENV_CLEARENV) + SETUP_ENV_CHANGEENV,
+ pw);
+
+#if ENABLE_PAM
+ /* Modules such as pam_env will setup the PAM environment,
+ * which should be copied into the new environment. */
+ pamenv = pam_getenvlist(pamh);
+ if (pamenv) while (*pamenv) {
+ putenv(*pamenv);
+ pamenv++;
+ }
+#endif
motd();
if (pw->pw_uid == 0)
syslog(LOG_INFO, "root login%s", fromhost);
-#if ENABLE_SELINUX
+
+ if (ENABLE_FEATURE_CLEAN_UP)
+ free(fromhost);
+
/* 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
+ IF_SELINUX(set_current_security_context(user_sid);)
// util-linux login also does:
// /* start new session */
// bb_setpgrp();
// If this stuff is really needed, add it and explain why!
- /* set signals to defaults */
- signal(SIGALRM, SIG_DFL);
+ /* Set signals to defaults */
+ /* Non-ignored signals revert to SIG_DFL on exec anyway */
+ /*signal(SIGALRM, SIG_DFL);*/
+
/* Is this correct? This way user can ctrl-c out of /etc/profile,
* potentially creating security breach (tested with bash 3.0).
* But without this, bash 3.0 will not enable ctrl-c either.
* Maybe bash is buggy?
* Need to find out what standards say about /bin/login -
- * should it leave SIGINT etc enabled or disabled? */
+ * should we leave SIGINT etc enabled or disabled? */
signal(SIGINT, SIG_DFL);
/* Exec login shell with no additional parameters */
- run_shell(tmp, 1, NULL, NULL);
+ run_shell(pw->pw_shell, 1, NULL, NULL);
/* return EXIT_FAILURE; - not reached */
}
projects / oweals / busybox.git / blobdiff