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runuser: new command (derived from su(1)) 

This command is based on su(1), the differences:

 - based on Fedora runuser su(1) patch
 - not installed with suid rights
 - allowed for root users only
 - don't ask for password
 - uses PAM session, for example:

$ cat /etc/pam.d/runuser
auth		sufficient	pam_rootok.so
session		optional	pam_keyinit.so revoke
session		required	pam_limits.so
session		required	pam_unix.so

$ cat /etc/pam.d/runuser-l
auth		include		runuser
session		optional	pam_keyinit.so force revoke
session		include		runuser

Signed-off-by: Karel Zak <kzak@redhat.com>
This commit is contained in:
Karel Zak 2012-08-29 17:34:26 +02:00
parent cf1a99dacc
commit 7ec6adb1cc
6 changed files with 303 additions and 8 deletions
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1
.gitignore vendored
View File

@ -138,6 +138,7 @@ tests/run.sh.trs
/resizepart
/rev
/rtcwake
/runuser
/sample-mkfs
/sample-partitions
/sample-superblocks

9
configure.ac
View File

@ -1154,6 +1154,15 @@ UL_REQUIRES_HAVE([su], [security_pam_misc_h], [PAM header file])
AM_CONDITIONAL(BUILD_SU, test "x$build_su" = xyes)
AC_ARG_ENABLE([runuser],
AS_HELP_STRING([--disable-runuser], [do not build runuser]),
[], enable_runuser=yes
)
UL_BUILD_INIT([runuser])
UL_REQUIRES_HAVE([runuser], [security_pam_misc_h], [PAM header file])
AM_CONDITIONAL(BUILD_RUNUSER, test "x$build_runuser" = xyes)
AC_ARG_ENABLE([schedutils],
AS_HELP_STRING([--disable-schedutils], [do not build chrt, ionice, teskset]),
[], enable_schedutils=yes

13
login-utils/Makemodule.am
View File

@ -92,6 +92,19 @@ su_LDADD = $(LDADD) -lpam -lpam_misc
endif
if BUILD_RUNUSER
bin_PROGRAMS += runuser
dist_man_MANS += login-utils/runuser.1
runuser_SOURCES = \
login-utils/runuser.c \
login-utils/su-common.c \
login-utils/su-common.h \
login-utils/logindefs.c \
login-utils/logindefs.h
runuser_LDADD = $(LDADD) -lpam -lpam_misc
endif
if BUILD_NEWGRP
usrbin_exec_PROGRAMS += newgrp
dist_man_MANS += login-utils/newgrp.1

230
login-utils/runuser.1 Normal file
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@ -0,0 +1,230 @@
.TH RUNUSER "1" "August 2012" "util-linux" "User Commands"
.SH NAME
runuser \- run a command with substitute user and group ID
.SH SYNOPSIS
.B runuser
[options...] [\-] [user [args...]]
.SH DESCRIPTION
.B runuser
allows to run commands with substitute user and group ID.
The difference between the commands
.B runuser
and
.B su
is that
.B runuser
does not ask for password, because it may be executed by root user only.
The command
.B runuser
does not have to be installed with suid permissions.
.PP
When called without arguments
.B runuser
defaults to running an interactive shell as
.IR root .
.PP
For backward compatibility
.B runuser
defaults to not change the current directory and to only set the
environment variables
.B HOME
and
.B SHELL
(plus
.B USER
and
.B LOGNAME
if the target
.I user
is not root). It is recommended to always use the
.B \-\-login
option (instead it's shortcut
.BR \- )
to avoid side effects caused by mixing environments.
.PP
This version of
.B runuser
uses PAM for session management.
.SH OPTIONS
.TP
\fB\-c\fR \fIcommand\fR, \fB\-\-command\fR=\fIcommand\fR
Pass
.I command
to the shell with the
.B \-c
option.
.TP
\fB\-\-session\-command\fR=\fIcommand\fR
Same as
.B \-c
but do not create a new session (discouraged).
.TP
\fB\-f\fR, \fB\-\-fast\fR
Pass
.B \-f
to the shell which may or may not be useful depending on the
shell.
.TP
\fB\-g\fR, \fB\-\-group\fR=\fIgroup\fR\fR
specify the primary group, this option is allowed for root user only
.TP
\fB\-G\fR, \fB\-\-supp-group\fR=\fIgroup\fR\fR
specify a supplemental group, this option is allowed for root user only
.TP
\fB\-\fR, \fB\-l\fR, \fB\-\-login\fR
Starts the shell as login shell with an environment similar to a real
login:
.RS 10
.TP
o
clears all environment variables except for
.B TERM
.TP
o
initializes the environment variables
.BR HOME ,
.BR SHELL ,
.BR USER ,
.BR LOGNAME ,
.B PATH
.TP
o
changes to the target user's home directory
.TP
o
sets argv[0] of the shell to
.RB ' \- '
in order to make the shell a login shell
.RE
.TP
\fB\-m\fR, \fB\-p\fR, \fB\-\-preserve-environment\fR
Preserves the whole environment, ie does not set
.BR HOME ,
.BR SHELL ,
.B USER
nor
.BR LOGNAME .
.TP
\fB\-s\fR \fISHELL\fR, \fB\-\-shell\fR=\fISHELL\fR
Runs the specified shell instead of the default. The shell to run is
selected according to the following rules in order:
.RS 10
.TP
o
the shell specified with
.B \-\-shell
.TP
o
The shell specified in the environment variable
.B SHELL
if the
.B \-\-preserve-environment
option is used.
.TP
o
the shell listed in the passwd entry of the target user
.TP
o
/bin/sh
.RE
.IP
If the target user has a restricted shell (i.e. not listed in
/etc/shells) the
.B \-\-shell
option and the
.B SHELL
environment variables are ignored unless the calling user is root.
.TP
\fB\-\-help\fR
Display help text and exit.
.TP
\fB\-\-version\fR
Display version information and exit.
.SH CONFIG FILES
.B runuser
reads the
.I /etc/default/runuser
and
.I /etc/login.defs
configuration files. The following configuration items are relevant
for
.BR runuser :
.PP
.B ENV_PATH
(string)
.RS 4
Defines the PATH environment variable for a regular user. The
default value is
.IR /usr/local/bin:\:/bin:\:/usr/bin .
.RE
.PP
.B ENV_ROOTPATH
(string)
.br
.B ENV_SUPATH
(string)
.RS 4
Defines the PATH environment variable for root. The default value is
.IR /usr/local/sbin:\:/usr/local/bin:\:/sbin:\:/bin:\:/usr/sbin:\:/usr/bin .
.RE
.PP
.B ALWAYS_SET_PATH
(boolean)
.RS 4
If set to
.I yes
and \-\-login and \-\-preserve\-environment were not specified
.B runuser
initializes
.BR PATH .
.RE
.SH EXIT STATUS
.B runuser
normally returns the exit status of the command it executed. If the
command was killed by a signal,
.B runuser
returns the number of the signal plus 128.
.PP
Exit status generated by
.B runuser
itself:
.RS 10
.TP
1
Generic error before executing the requested command
.TP
126
The requested command could not be executed
.TP
127
The requested command could was not found
.RE
.SH FILES
.PD 0
.TP 17
/etc/pam.d/runuser
default PAM configuration file
.TP
/etc/pam.d/runuser-l
PAM configuration file if \-\-login is specified
.TP
/etc/default/runuser
runuser specific logindef config file
.TP
/etc/login.defs
global logindef config file
.PD 1
.SH "SEE ALSO"
.BR pam (8),
.BR shells (5),
.BR login.defs (5),
.BR su (1)
.SH AUTHOR
Derived from coreutils' su which was based on an implemenation from
David MacKenzie and Fedora runuser command from Dan Walsh.
.SH AVAILABILITY
The runuser command is part of the util-linux package and is
available from
.UR ftp://\:ftp.kernel.org\:/pub\:/linux\:/utils\:/util-linux/
Linux Kernel Archive
.UE .

7
login-utils/runuser.c Normal file
View File

@ -0,0 +1,7 @@
#include "su-common.h"
int main(int argv, char **argc)
{
return su_main(argv, argc, RUNUSER_MODE);
}

51
login-utils/su-common.c
View File

@ -65,8 +65,14 @@ enum
#include "env.h"
/* name of the pam configuration files. separate configs for su and su - */
#define PAM_SERVICE_NAME "su"
#define PAM_SERVICE_NAME_L "su-l"
#define PAM_SRVNAME_SU "su"
#define PAM_SRVNAME_SU_L "su-l"
#define PAM_SRVNAME_RUNUSER "runuser"
#define PAM_SRVNAME_RUNUSER_L "runuser-l"
#define _PATH_LOGINDEFS_SU "/etc/defaults/su"
#define _PATH_LOGINDEFS_RUNUSER "/etc/defaults/runuser"
#define is_pam_failure(_rc) ((_rc) != PAM_SUCCESS)
@ -106,6 +112,8 @@ static bool _pam_cred_established;
static sig_atomic_t volatile caught_signal = false;
static pam_handle_t *pamh = NULL;
static int restricted = 1; /* zero for root user */
static struct option const longopts[] =
{
{"command", required_argument, NULL, 'c'},
@ -146,7 +154,8 @@ log_su (struct passwd const *pw, bool successful)
openlog (program_invocation_short_name, 0 , LOG_AUTH);
syslog (LOG_NOTICE, "%s(to %s) %s on %s",
successful ? "" : "FAILED SU ",
successful ? "" :
su_mode == RUNUSER_MODE ? "FAILED RUNUSER " : "FAILED SU ",
new_user, old_user, tty);
closelog ();
}
@ -315,11 +324,19 @@ static void
authenticate (const struct passwd *pw)
{
const struct passwd *lpw;
const char *cp;
const char *cp, *srvname = NULL;
int retval;
retval = pam_start (simulate_login ? PAM_SERVICE_NAME_L : PAM_SERVICE_NAME,
pw->pw_name, &conv, &pamh);
switch (su_mode) {
case SU_MODE:
srvname = simulate_login ? PAM_SRVNAME_SU_L : PAM_SRVNAME_SU;
break;
case RUNUSER_MODE:
srvname = simulate_login ? PAM_SRVNAME_RUNUSER_L : PAM_SRVNAME_RUNUSER;
break;
}
retval = pam_start (srvname, pw->pw_name, &conv, &pamh);
if (is_pam_failure(retval))
goto done;
@ -344,6 +361,17 @@ authenticate (const struct passwd *pw)
goto done;
}
if (su_mode == RUNUSER_MODE)
{
/*
* This is the only difference between runuser(1) and su(1). The command
* runuser(1) does not required authentication, because user is root.
*/
if (restricted)
errx(EXIT_FAILURE, _("may not be used by non-root users"));
return;
}
retval = pam_authenticate (pamh, 0);
if (is_pam_failure(retval))
goto done;
@ -691,7 +719,15 @@ usage (int status)
static
void load_config(void)
{
logindefs_load_file("/etc/default/su");
switch (su_mode) {
case SU_MODE:
logindefs_load_file(_PATH_LOGINDEFS_SU);
break;
case RUNUSER_MODE:
logindefs_load_file(_PATH_LOGINDEFS_RUNUSER);
break;
}
logindefs_load_file(_PATH_LOGINDEFS);
}
@ -722,7 +758,6 @@ su_main (int argc, char **argv, int mode)
gid_t groups[NGROUPS_MAX];
int num_supp_groups = 0;
int use_gid = 0;
int restricted;
setlocale (LC_ALL, "");
bindtextdomain (PACKAGE, LOCALEDIR);