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sulogin: increase util-linux compatibility

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Change to root's HOME. Set some envvars. Steal ctty if necessary and possible.

function                                             old     new   delta
sulogin_main                                         240     340    +100
setup_environment                                    225     233      +8
su_main                                              479     474      -5
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 2/1 up/down: 108/-5)            Total: 103 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2022-01-12 23:19:11 +01:00
parent 004cefa918
commit d162a7b978
3 changed files with 37 additions and 12 deletions
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18
include/libbb.h
View File

@ -1726,15 +1726,16 @@ extern void selinux_or_die(void) FAST_FUNC;
/* setup_environment:
* if chdir pw->pw_dir: ok: else if to_tmp == 1: goto /tmp else: goto / or die
* if clear_env = 1: cd(pw->pw_dir), clear environment, then set
* if !SETUP_ENV_NO_CHDIR:
* if cd(pw->pw_dir): ok: else if SETUP_ENV_TO_TMP: cd(/tmp) else: cd(/) or die
* if SETUP_ENV_CLEARENV: cd(pw->pw_dir), clear environment, then set
* TERM=(old value)
* USER=pw->pw_name, LOGNAME=pw->pw_name
* PATH=bb_default_[root_]path
* HOME=pw->pw_dir
* SHELL=shell
* else if change_env = 1:
* if not root (if pw->pw_uid != 0):
* else if SETUP_ENV_CHANGEENV:
* if not root (if pw->pw_uid != 0) or if SETUP_ENV_CHANGEENV_LOGNAME:
* USER=pw->pw_name, LOGNAME=pw->pw_name
* HOME=pw->pw_dir
* SHELL=shell
@ -1743,10 +1744,11 @@ extern void selinux_or_die(void) FAST_FUNC;
* NB: CHANGEENV and CLEARENV use setenv() - this leaks memory!
* If setup_environment() is used is vforked child, this leaks memory _in parent too_!
*/
#define SETUP_ENV_CHANGEENV (1 << 0)
#define SETUP_ENV_CLEARENV (1 << 1)
#define SETUP_ENV_TO_TMP (1 << 2)
#define SETUP_ENV_NO_CHDIR (1 << 4)
#define SETUP_ENV_CHANGEENV (1 << 0)
#define SETUP_ENV_CHANGEENV_LOGNAME (1 << 1)
#define SETUP_ENV_CLEARENV (1 << 2)
#define SETUP_ENV_TO_TMP (1 << 3)
#define SETUP_ENV_NO_CHDIR (1 << 4)
void setup_environment(const char *shell, int flags, const struct passwd *pw) FAST_FUNC;
void nuke_str(char *str) FAST_FUNC;
#if ENABLE_FEATURE_SECURETTY && !ENABLE_PAM

8
libbb/setup_environment.c
View File

@ -54,15 +54,15 @@ void FAST_FUNC setup_environment(const char *shell, int flags, const struct pass
xsetenv("TERM", term);
xsetenv("PATH", (pw->pw_uid ? bb_default_path : bb_default_root_path));
goto shortcut;
// No, gcc (4.2.1) is not clever enougn to do it itself.
// No, gcc (4.2.1) is not clever enough to do it itself.
//xsetenv("USER", pw->pw_name);
//xsetenv("LOGNAME", pw->pw_name);
//xsetenv("HOME", pw->pw_dir);
//xsetenv("SHELL", shell);
} else if (flags & SETUP_ENV_CHANGEENV) {
/* Set HOME, SHELL, and if not becoming a super-user,
* USER and LOGNAME. */
if (pw->pw_uid) {
/* Set HOME, SHELL, and if not becoming a super-user
* or if SETUP_ENV_CHANGEENV_LOGNAME, USER and LOGNAME. */
if ((flags & SETUP_ENV_CHANGEENV_LOGNAME) || pw->pw_uid != 0) {
shortcut:
xsetenv("USER", pw->pw_name);
xsetenv("LOGNAME", pw->pw_name);

23
loginutils/sulogin.c
View File

@ -28,6 +28,7 @@
int sulogin_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int sulogin_main(int argc UNUSED_PARAM, char **argv)
{
int tsid;
int timeout = 0;
struct passwd *pwd;
const char *shell;
@ -88,6 +89,28 @@ int sulogin_main(int argc UNUSED_PARAM, char **argv)
if (!shell)
shell = pwd->pw_shell;
/* util-linux 2.36.1 compat: cd to root's HOME, set a few envvars */
setup_environment(shell, SETUP_ENV_CHANGEENV | SETUP_ENV_CHANGEENV_LOGNAME, pwd);
// no SETUP_ENV_CLEARENV
// SETUP_ENV_CHANGEENV[+LOGNAME] - set HOME, SHELL, USER,and LOGNAME
// no SETUP_ENV_NO_CHDIR - IOW: cd to $HOME
/* util-linux 2.36.1 compat: steal ctty if we don't have it yet
* (yes, util-linux uses force=1) */
tsid = tcgetsid(STDIN_FILENO);
if (tsid < 0 || getpid() != tsid) {
if (ioctl(STDIN_FILENO, TIOCSCTTY, /*force:*/ (long)1) != 0) {
// bb_perror_msg("TIOCSCTTY1 tsid:%d", tsid);
if (setsid() > 0) {
// bb_error_msg("done setsid()");
/* If it still does not work, ignore */
if (ioctl(STDIN_FILENO, TIOCSCTTY, /*force:*/ (long)1) != 0) {
// bb_perror_msg("TIOCSCTTY2 tsid:%d", tsid);
}
}
}
}
/* Exec login shell with no additional parameters. Never returns. */
exec_login_shell(shell);
}