/*
* Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
*/
-
-#include "busybox.h"
-#include <utmp.h>
-#include <sys/resource.h>
+#include "libbb.h"
#include <syslog.h>
+#if ENABLE_FEATURE_UTMP
+# include <utmp.h> /* USER_PROCESS */
+#endif
+#include <sys/resource.h>
-#ifdef CONFIG_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 <errno.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 */
+#endif
+
+#if ENABLE_PAM
+/* PAM may include <locale.h>. We may need to undefine bbox's stub define: */
+# 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>
+static const struct pam_conv conv = {
+ misc_conv,
+ NULL
+};
#endif
enum {
TTYNAME_SIZE = 32,
};
-static char full_tty[TTYNAME_SIZE];
-static char* short_tty = full_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 struct utmp utent;
+static char* short_tty;
-static void read_or_build_utent(int picky)
+#if ENABLE_FEATURE_NOLOGIN
+static void die_if_nologin(void)
{
- struct utmp *ut;
- pid_t pid = getpid();
-
- setutent();
+ FILE *fp;
+ int c;
+ int empty = 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;
+ fp = fopen_for_read("/etc/nologin");
+ if (!fp) /* assuming it does not exist */
+ return;
- /* If there is one, just use it, otherwise create a new one. */
- if (ut) {
- utent = *ut;
- } else {
- if (picky)
- bb_error_msg_and_die("no utmp entry found");
-
- memset(&utent, 0, sizeof(utent));
- utent.ut_type = LOGIN_PROCESS;
- utent.ut_pid = pid;
- strncpy(utent.ut_line, short_tty, sizeof(utent.ut_line));
- /* This one is only 4 chars wide. Try to fit something
- * remotely meaningful by skipping "tty"... */
- strncpy(utent.ut_id, short_tty + 3, sizeof(utent.ut_id));
- strncpy(utent.ut_user, "LOGIN", sizeof(utent.ut_user));
- utent.ut_time = time(NULL);
+ while ((c = getc(fp)) != EOF) {
+ if (c == '\n')
+ bb_putchar('\r');
+ bb_putchar(c);
+ empty = 0;
}
- if (!picky) /* root login */
- memset(utent.ut_host, 0, sizeof(utent.ut_host));
+ if (empty)
+ puts("\r\nSystem closed for routine maintenance\r");
+
+ fclose(fp);
+ fflush_all();
+ /* Users say that they do need this prior to exit: */
+ tcdrain(STDOUT_FILENO);
+ exit(EXIT_FAILURE);
}
+#else
+# define die_if_nologin() ((void)0)
+#endif
-/*
- * 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(const char *username)
+#if ENABLE_FEATURE_SECURETTY && !ENABLE_PAM
+static int check_securetty(void)
{
- utent.ut_type = USER_PROCESS;
- strncpy(utent.ut_user, username, sizeof(utent.ut_user));
- utent.ut_time = time(NULL);
- /* other fields already filled in by read_or_build_utent above */
- setutent();
- pututline(&utent);
- endutent();
-#if ENABLE_FEATURE_WTMP
- if (access(bb_path_wtmp_file, R_OK|W_OK) == -1) {
- close(creat(bb_path_wtmp_file, 0664));
+ char *buf = (char*)"/etc/securetty"; /* any non-NULL is ok */
+ parser_t *parser = config_open2("/etc/securetty", fopen_for_read);
+ while (config_read(parser, &buf, 1, 1, "# \t", PARSE_NORMAL)) {
+ if (strcmp(buf, short_tty) == 0)
+ break;
+ buf = NULL;
}
- updwtmp(bb_path_wtmp_file, &utent);
-#endif
+ config_close(parser);
+ /* buf != NULL here if config file was not found, empty
+ * or line was found which equals short_tty */
+ return buf != NULL;
}
-#else /* !ENABLE_FEATURE_UTMP */
-static inline void read_or_build_utent(int ATTRIBUTE_UNUSED picky) {}
-static inline void write_utent(const char ATTRIBUTE_UNUSED *username) {}
-#endif /* !ENABLE_FEATURE_UTMP */
+#else
+static ALWAYS_INLINE int check_securetty(void) { return 1; }
+#endif
-static void die_if_nologin_and_non_root(int amroot)
+#if ENABLE_SELINUX
+static void initselinux(char *username, char *full_tty,
+ security_context_t *user_sid)
{
- FILE *fp;
- int c;
+ security_context_t old_tty_sid, new_tty_sid;
- if (access(bb_path_nologin_file, F_OK))
+ if (!is_selinux_enabled())
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 (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_FEATURE_SECURETTY
-static int check_securetty(void)
+#if ENABLE_LOGIN_SCRIPTS
+static void run_login_script(struct passwd *pw, char *full_tty)
{
- 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;
+ 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");
}
- 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; }
+void run_login_script(struct passwd *pw, char *full_tty);
#endif
static void get_username_or_die(char *buf, int size_buf)
{
int c, cntdown;
+
cntdown = EMPTY_USERNAME_COUNT;
-prompt:
- /* skip whitespace */
+ prompt:
print_login_prompt();
+ /* skip whitespace */
do {
c = getchar();
- if (c == EOF) exit(1);
+ if (c == EOF)
+ exit(EXIT_FAILURE);
if (c == '\n') {
- if (!--cntdown) exit(1);
+ 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(1);
+ exit(EXIT_FAILURE);
if (!strchr(buf, '\n'))
- exit(1);
- while (isgraph(*buf)) buf++;
+ exit(EXIT_FAILURE);
+ while ((unsigned char)*buf > ' ')
+ buf++;
*buf = '\0';
}
static void motd(void)
{
- FILE *fp;
- int c;
+ int fd;
- fp = fopen(bb_path_motd_file, "r");
- if (fp) {
- while ((c = getc(fp)) != EOF)
- putchar(c);
- fclose(fp);
+ fd = open(bb_path_motd_file, O_RDONLY);
+ if (fd >= 0) {
+ fflush_all();
+ bb_copyfd_eof(fd, STDOUT_FILENO);
+ close(fd);
}
}
-static void nonblock(int fd)
-{
- fcntl(fd, F_SETFL, O_NONBLOCK | fcntl(fd, F_GETFL));
-}
-
-static void alarm_handler(int sig ATTRIBUTE_UNUSED)
+static void alarm_handler(int sig UNUSED_PARAM)
{
/* 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 */
- nonblock(1);
- nonblock(2);
- bb_info_msg("\r\nLogin timed out after %d seconds\r", TIMEOUT);
- exit(EXIT_SUCCESS);
+ ndelay_on(1);
+ printf("\r\nLogin timed out after %d 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);
+ _exit(EXIT_SUCCESS);
}
-int login_main(int argc, char **argv);
-int login_main(int argc, char **argv)
+int login_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
+int login_main(int argc UNUSED_PARAM, char **argv)
{
enum {
LOGIN_OPT_f = (1<<0),
LOGIN_OPT_h = (1<<1),
LOGIN_OPT_p = (1<<2),
};
- char fromhost[512];
+ 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 = NULL;
- char *opt_user = NULL;
- USE_SELINUX(security_context_t user_sid = NULL;)
+ char *opt_user = opt_user; /* for compiler */
+ char *full_tty;
+ IF_SELINUX(security_context_t user_sid = NULL;)
+#if ENABLE_PAM
+ int pamret;
+ pam_handle_t *pamh;
+ const char *pamuser;
+ const char *failed_msg;
+ struct passwd pwdstruct;
+ char pwdbuf[256];
+#endif
username[0] = '\0';
- amroot = (getuid() == 0);
signal(SIGALRM, alarm_handler);
alarm(TIMEOUT);
- opt = getopt32(argc, argv, "f:h:p", &opt_user, &opt_host);
+ /* 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)
+ * and any extra open fd's are closed.
+ * (The name of the function is misleading. Not daemonizing here.) */
+ bb_daemonize_or_rexec(DAEMON_ONLY_SANITIZE | DAEMON_CLOSE_EXTRA_FDS, NULL);
+
+ 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 (optind < argc) /* user from command line (getty) */
- safe_strncpy(username, argv[optind], sizeof(username));
+ argv += optind;
+ 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))
+ if (!isatty(STDIN_FILENO) || !isatty(STDOUT_FILENO) || !isatty(STDERR_FILENO))
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;
- }
-
- read_or_build_utent(!amroot);
+ full_tty = xmalloc_ttyname(STDIN_FILENO);
+ if (!full_tty)
+ full_tty = xstrdup("UNKNOWN");
+ short_tty = full_tty;
+ if (strncmp(full_tty, "/dev/", 5) == 0)
+ short_tty += 5;
if (opt_host) {
- 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);
+ fromhost = xasprintf(" on '%s' from '%s'", short_tty, opt_host);
+ } else {
+ fromhost = xasprintf(" on '%s'", short_tty);
}
- else
- snprintf(fromhost, sizeof(fromhost)-1, " on '%.100s'", short_tty);
- bb_setpgrp;
+ /* 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);
+
if (!username[0])
get_username_or_die(username, sizeof(username));
+#if ENABLE_PAM
+ pamret = pam_start("login", username, &conv, &pamh);
+ if (pamret != PAM_SUCCESS) {
+ failed_msg = "start";
+ goto pam_auth_failed;
+ }
+ /* set TTY (so things like securetty work) */
+ pamret = pam_set_item(pamh, PAM_TTY, short_tty);
+ if (pamret != PAM_SUCCESS) {
+ 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)
+ */
+ }
+ /* check that the account is healthy */
+ pamret = pam_acct_mgmt(pamh, 0);
+ if (pamret != PAM_SUCCESS) {
+ failed_msg = "acct_mgmt";
+ goto pam_auth_failed;
+ }
+ /* read user back */
+ pamuser = NULL;
+ /* gcc: "dereferencing type-punned pointer breaks aliasing rules..."
+ * thus we cast to (void*) */
+ if (pam_get_item(pamh, PAM_USER, (void*)&pamuser) != PAM_SUCCESS) {
+ failed_msg = "get_item(USER)";
+ goto pam_auth_failed;
+ }
+ if (!pamuser || !pamuser[0])
+ goto auth_failed;
+ safe_strncpy(username, pamuser, sizeof(username));
+ /* Don't use "pw = getpwnam(username);",
+ * PAM is said to be capable of destroying static storage
+ * used by getpwnam(). We are using safe(r) function */
+ pw = NULL;
+ getpwnam_r(username, &pwdstruct, pwdbuf, sizeof(pwdbuf), &pw);
+ if (!pw)
+ goto auth_failed;
+ pamret = pam_open_session(pamh, 0);
+ if (pamret != PAM_SUCCESS) {
+ failed_msg = "open_session";
+ goto pam_auth_failed;
+ }
+ pamret = pam_setcred(pamh, PAM_ESTABLISH_CRED);
+ if (pamret != PAM_SUCCESS) {
+ failed_msg = "setcred";
+ goto pam_auth_failed;
+ }
+ break; /* success, continue login process */
+
+ pam_auth_failed:
+ /* 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 */
pw = getpwnam(username);
if (!pw) {
- safe_strncpy(username, "UNKNOWN", sizeof(username));
- goto auth_failed;
+ strcpy(username, "UNKNOWN");
+ goto fake_it;
}
if (pw->pw_passwd[0] == '!' || pw->pw_passwd[0] == '*')
/* 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))
break;
-
-auth_failed:
+#endif /* ENABLE_PAM */
+ auth_failed:
opt &= ~LOGIN_OPT_f;
bb_do_delay(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",
return EXIT_FAILURE;
}
username[0] = '\0';
- }
+ } /* while (1) */
alarm(0);
- die_if_nologin_and_non_root(pw->pw_uid == 0);
-
- write_utent(username);
+ /* 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();
-#ifdef CONFIG_SELINUX
- if (is_selinux_enabled()) {
- security_context_t old_tty_sid, new_tty_sid;
+ IF_SELINUX(initselinux(username, full_tty, &user_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);
- }
- }
-#endif
/* 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);
- /* TODO: be nommu-friendly, use spawn? */
- 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);
- BB_EXECVP(script, t_argv);
- exit(1);
- default: /* parent */
- wait(NULL);
- }
- }
- }
+ 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 && run_by_root)
+ run_login_script(pw, full_tty);
change_identity(pw);
tmp = pw->pw_shell;
if (!tmp || !*tmp)
tmp = DEFAULT_SHELL;
- setup_environment(tmp, 1, !(opt & LOGIN_OPT_p), pw);
+ setup_environment(tmp,
+ (!(opt & LOGIN_OPT_p) * SETUP_ENV_CLEARENV) + SETUP_ENV_CHANGEENV,
+ pw);
motd();
if (pw->pw_uid == 0)
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
+ IF_SELINUX(set_current_security_context(user_sid);)
// util-linux login also does:
// /* start new session */
// setsid();
// /* TIOCSCTTY: steal tty from other process group */
// if (ioctl(0, TIOCSCTTY, 1)) error_msg...
+ // BBox login used to do this (see above):
+ // bb_setpgrp();
+ // If this stuff is really needed, add it and explain why!
+
+ /* Set signals to defaults */
+ /* Non-ignored signals revert to SIG_DFL on exec anyway */
+ /*signal(SIGALRM, SIG_DFL);*/
- /* set signals to defaults */
- 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);
- run_shell(tmp, 1, 0, 0); /* exec the shell finally */
+ /* Exec login shell with no additional parameters */
+ run_shell(tmp, 1, NULL, NULL);
- return EXIT_FAILURE;
+ /* return EXIT_FAILURE; - not reached */
}
projects / oweals / busybox.git / blobdiff