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selinux/policycoreutils/newrole/newrole.c

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/************************************************************************
*
* newrole
*
* SYNOPSIS:
*
* This program allows a user to change their SELinux RBAC role and/or
* SELinux TE type (domain) in a manner similar to the way the traditional
* UNIX su program allows a user to change their identity.
*
* USAGE:
*
* newrole [ -r role ] [ -t type ] [ -l level ] [ -V ] [ -- args ]
*
* BUILD OPTIONS:
*
* option USE_PAM:
*
* Set the USE_PAM constant if you want to authenticate users via PAM.
* If USE_PAM is not set, users will be authenticated via direct
* access to the shadow password file.
*
* If you decide to use PAM must be told how to handle newrole. A
* good rule-of-thumb might be to tell PAM to handle newrole in the
* same way it handles su, except that you should remove the pam_rootok.so
* entry so that even root must re-authenticate to change roles.
*
* If you choose not to use PAM, make sure you have a shadow passwd file
* in /etc/shadow. You can use a symlink if your shadow passwd file
* lives in another directory. Example:
* su
* cd /etc
* ln -s /etc/auth/shadow shadow
*
* If you decide not to use PAM, you will also have to make newrole
* setuid root, so that it can read the shadow passwd file.
*
*
* Authors:
* Anthony Colatrella
* Tim Fraser
* Steve Grubb <sgrubb@redhat.com>
* Darrel Goeddel <DGoeddel@trustedcs.com>
* Michael Thompson <mcthomps@us.ibm.com>
* Dan Walsh <dwalsh@redhat.com>
*
*************************************************************************/
#define _GNU_SOURCE
#if defined(AUDIT_LOG_PRIV) && !defined(USE_AUDIT)
#error AUDIT_LOG_PRIV needs the USE_AUDIT option
#endif
#if defined(NAMESPACE_PRIV) && !defined(USE_PAM)
#error NAMESPACE_PRIV needs the USE_PAM option
#endif
#include <stdio.h>
#include <stdlib.h> /* for malloc(), realloc(), free() */
#include <pwd.h> /* for getpwuid() */
#include <ctype.h>
#include <sys/types.h> /* to make getuid() and getpwuid() happy */
#include <sys/wait.h> /* for wait() */
#include <getopt.h> /* for getopt_long() form of getopt() */
#include <fcntl.h>
#include <string.h>
#include <errno.h>
#include <selinux/selinux.h> /* for is_selinux_enabled() */
#include <selinux/context.h> /* for context-mangling functions */
#include <selinux/get_default_type.h>
#include <selinux/get_context_list.h> /* for SELINUX_DEFAULTUSER */
#include <signal.h>
#include <unistd.h> /* for getuid(), exit(), getopt() */
#ifdef USE_AUDIT
#include <libaudit.h>
#endif
#if defined(AUDIT_LOG_PRIV) || defined(NAMESPACE_PRIV)
#include <sys/prctl.h>
#include <cap-ng.h>
#endif
#ifdef USE_NLS
#include <locale.h> /* for setlocale() */
#include <libintl.h> /* for gettext() */
#define _(msgid) gettext (msgid)
#else
#define _(msgid) (msgid)
#endif
#ifndef PACKAGE
#define PACKAGE "policycoreutils" /* the name of this package lang translation */
#endif
#define TRUE 1
#define FALSE 0
/* USAGE_STRING describes the command-line args of this program. */
#define USAGE_STRING "USAGE: newrole [ -r role ] [ -t type ] [ -l level ] [ -p ] [ -V ] [ -- args ]"
#ifdef USE_PAM
#define PAM_SERVICE_CONFIG "/etc/selinux/newrole_pam.conf";
#endif
#define DEFAULT_PATH "/usr/bin:/bin"
#define DEFAULT_CONTEXT_SIZE 255 /* first guess at context size */
extern char **environ;
/**
* Construct from the current range and specified desired level a resulting
* range. If the specified level is a range, return that. If it is not, then
* construct a range with level as the sensitivity and clearance of the current
* context.
*
* newlevel - the level specified on the command line
* range - the range in the current context
*
* Returns malloc'd memory
*/
static char *build_new_range(char *newlevel, const char *range)
{
char *newrangep = NULL;
const char *tmpptr;
size_t len;
/* a missing or empty string */
if (!range || !strlen(range) || !newlevel || !strlen(newlevel))
return NULL;
/* if the newlevel is actually a range - just use that */
if (strchr(newlevel, '-')) {
newrangep = strdup(newlevel);
return newrangep;
}
/* look for MLS range in current context */
tmpptr = strchr(range, '-');
if (tmpptr) {
/* we are inserting into a ranged MLS context */
len = strlen(newlevel) + 1 + strlen(tmpptr + 1) + 1;
newrangep = (char *)malloc(len);
if (!newrangep)
return NULL;
snprintf(newrangep, len, "%s-%s", newlevel, tmpptr + 1);
} else {
/* we are inserting into a currently non-ranged MLS context */
if (!strcmp(newlevel, range)) {
newrangep = strdup(range);
} else {
len = strlen(newlevel) + 1 + strlen(range) + 1;
newrangep = (char *)malloc(len);
if (!newrangep)
return NULL;
snprintf(newrangep, len, "%s-%s", newlevel, range);
}
}
return newrangep;
}
#ifdef USE_PAM
/************************************************************************
*
* All PAM code goes in this section.
*
************************************************************************/
#include <security/pam_appl.h> /* for PAM functions */
#include <security/pam_misc.h> /* for misc_conv PAM utility function */
const char *service_name = "newrole";
/* authenticate_via_pam()
*
* in: pw - struct containing data from our user's line in
* the passwd file.
* out: nothing
* return: value condition
* ----- ---------
* 1 PAM thinks that the user authenticated themselves properly
* 0 otherwise
*
* This function uses PAM to authenticate the user running this
* program. This is the only function in this program that makes PAM
* calls.
*/
int authenticate_via_pam(const char *ttyn, pam_handle_t * pam_handle)
{
int result = 0; /* set to 0 (not authenticated) by default */
int pam_rc; /* pam return code */
const char *tty_name;
if (ttyn) {
if (strncmp(ttyn, "/dev/", 5) == 0)
tty_name = ttyn + 5;
else
tty_name = ttyn;
pam_rc = pam_set_item(pam_handle, PAM_TTY, tty_name);
if (pam_rc != PAM_SUCCESS) {
fprintf(stderr, _("failed to set PAM_TTY\n"));
goto out;
}
}
/* Ask PAM to authenticate the user running this program */
pam_rc = pam_authenticate(pam_handle, 0);
if (pam_rc != PAM_SUCCESS) {
goto out;
}
/* Ask PAM to verify acct_mgmt */
pam_rc = pam_acct_mgmt(pam_handle, 0);
if (pam_rc == PAM_SUCCESS) {
result = 1; /* user authenticated OK! */
}
out:
return result;
} /* authenticate_via_pam() */
#include "hashtab.h"
static int free_hashtab_entry(hashtab_key_t key, hashtab_datum_t d,
void *args __attribute__ ((unused)))
{
free(key);
free(d);
return 0;
}
static unsigned int reqsymhash(hashtab_t h, const_hashtab_key_t key)
{
char *p, *keyp;
size_t size;
unsigned int val;
val = 0;
keyp = (char *)key;
size = strlen(keyp);
for (p = keyp; ((size_t) (p - keyp)) < size; p++)
val =
(val << 4 | (val >> (8 * sizeof(unsigned int) - 4))) ^ (*p);
return val & (h->size - 1);
}
static int reqsymcmp(hashtab_t h
__attribute__ ((unused)), const_hashtab_key_t key1,
const_hashtab_key_t key2)
{
return strcmp(key1, key2);
}
static hashtab_t app_service_names = NULL;
#define PAM_SERVICE_SLOTS 64
static int process_pam_config(FILE * cfg)
{
const char *config_file_path = PAM_SERVICE_CONFIG;
char *line_buf = NULL;
unsigned long lineno = 0;
size_t len = 0;
char *app = NULL;
char *service = NULL;
int ret;
while (getline(&line_buf, &len, cfg) > 0) {
char *buffer = line_buf;
lineno++;
while (isspace(*buffer))
buffer++;
if (buffer[0] == '#')
continue;
if (buffer[0] == '\n' || buffer[0] == '\0')
continue;
app = service = NULL;
ret = sscanf(buffer, "%ms %ms\n", &app, &service);
if (ret < 2 || !app || !service)
goto err;
ret = hashtab_insert(app_service_names, app, service);
if (ret == HASHTAB_OVERFLOW) {
fprintf(stderr,
_
("newrole: service name configuration hashtable overflow\n"));
goto err;
}
}
free(line_buf);
return 0;
err:
free(app);
free(service);
fprintf(stderr, _("newrole: %s: error on line %lu.\n"),
config_file_path, lineno);
free(line_buf);
return -1;
}
/*
* Read config file ignoring comment lines.
* Files specified one per line executable with a corresponding
* pam service name.
*/
static int read_pam_config(void)
{
const char *config_file_path = PAM_SERVICE_CONFIG;
FILE *cfg = NULL;
cfg = fopen(config_file_path, "r");
if (!cfg)
return 0; /* This configuration is optional. */
app_service_names =
hashtab_create(reqsymhash, reqsymcmp, PAM_SERVICE_SLOTS);
if (!app_service_names)
goto err;
if (process_pam_config(cfg))
goto err;
fclose(cfg);
return 0;
err:
fclose(cfg);
return -1;
}
#else /* else !USE_PAM */
/************************************************************************
*
* All shadow passwd code goes in this section.
*
************************************************************************/
#include <shadow.h> /* for shadow passwd functions */
#include <string.h> /* for strlen(), memset() */
#define PASSWORD_PROMPT _("Password:") /* prompt for getpass() */
/* authenticate_via_shadow_passwd()
*
* in: uname - the calling user's user name
* out: nothing
* return: value condition
* ----- ---------
* 1 user authenticated themselves properly according to the
* shadow passwd file.
* 0 otherwise
*
* This function uses the shadow passwd file to thenticate the user running
* this program.
*/
int authenticate_via_shadow_passwd(const char *uname)
{
struct spwd *p_shadow_line;
char *unencrypted_password_s;
char *encrypted_password_s;
setspent();
p_shadow_line = getspnam(uname);
endspent();
if (!(p_shadow_line)) {
fprintf(stderr, _("Cannot find your entry in the shadow "
"passwd file.\n"));
return 0;
}
/* Ask user to input unencrypted password */
if (!(unencrypted_password_s = getpass(PASSWORD_PROMPT))) {
fprintf(stderr, _("getpass cannot open /dev/tty\n"));
return 0;
}
/* Use crypt() to encrypt user's input password. */
encrypted_password_s = crypt(unencrypted_password_s,
p_shadow_line->sp_pwdp);
memset(unencrypted_password_s, 0, strlen(unencrypted_password_s));
return (!strcmp(encrypted_password_s, p_shadow_line->sp_pwdp));
}
#endif /* if/else USE_PAM */
/**
* This function checks to see if the shell is known in /etc/shells.
* If so, it returns 1. On error or illegal shell, it returns 0.
*/
static int verify_shell(const char *shell_name)
{
int found = 0;
const char *buf;
if (!(shell_name && shell_name[0]))
return found;
while ((buf = getusershell()) != NULL) {
/* ignore comments */
if (*buf == '#')
continue;
/* check the shell skipping newline char */
if (!strcmp(shell_name, buf)) {
found = 1;
break;
}
}
endusershell();
return found;
}
/**
* Determine the Linux user identity to re-authenticate.
* If supported and set, use the login uid, as this should be more stable.
* Otherwise, use the real uid.
*
* This function assigns malloc'd memory into the pw_copy struct.
* Returns zero on success, non-zero otherwise
*/
static int extract_pw_data(struct passwd *pw_copy)
{
uid_t uid;
struct passwd *pw;
#ifdef USE_AUDIT
uid = audit_getloginuid();
if (uid == (uid_t) - 1)
uid = getuid();
#else
uid = getuid();
#endif
setpwent();
pw = getpwuid(uid);
endpwent();
if (!(pw && pw->pw_name && pw->pw_name[0] && pw->pw_shell
&& pw->pw_shell[0] && pw->pw_dir && pw->pw_dir[0])) {
fprintf(stderr,
_("cannot find valid entry in the passwd file.\n"));
return -1;
}
*pw_copy = *pw;
pw = pw_copy;
pw->pw_name = strdup(pw->pw_name);
pw->pw_dir = strdup(pw->pw_dir);
pw->pw_shell = strdup(pw->pw_shell);
if (!(pw->pw_name && pw->pw_dir && pw->pw_shell)) {
fprintf(stderr, _("Out of memory!\n"));
goto out_free;
}
if (verify_shell(pw->pw_shell) == 0) {
fprintf(stderr, _("Error! Shell is not valid.\n"));
goto out_free;
}
return 0;
out_free:
free(pw->pw_name);
free(pw->pw_dir);
free(pw->pw_shell);
pw->pw_name = NULL;
pw->pw_dir = NULL;
pw->pw_shell = NULL;
return -1;
}
/**
* Either restore the original environment, or set up a minimal one.
*
* The minimal environment contains:
* TERM, DISPLAY and XAUTHORITY - if they are set, preserve values
* HOME, SHELL, USER and LOGNAME - set to contents of /etc/passwd
* PATH - set to default value DEFAULT_PATH
*
* Returns zero on success, non-zero otherwise
*/
static int restore_environment(int preserve_environment,
char **old_environ, const struct passwd *pw)
{
char const *term_env;
char const *display_env;
char const *xauthority_env;
char *term = NULL; /* temporary container */
char *display = NULL; /* temporary container */
char *xauthority = NULL; /* temporary container */
int rc;
environ = old_environ;
if (preserve_environment)
return 0;
term_env = getenv("TERM");
display_env = getenv("DISPLAY");
xauthority_env = getenv("XAUTHORITY");
/* Save the variable values we want */
if (term_env)
term = strdup(term_env);
if (display_env)
display = strdup(display_env);
if (xauthority_env)
xauthority = strdup(xauthority_env);
if ((term_env && !term) || (display_env && !display) ||
(xauthority_env && !xauthority)) {
rc = -1;
goto out;
}
/* Construct a new environment */
if ((rc = clearenv())) {
fprintf(stderr, _("Unable to clear environment\n"));
goto out;
}
/* Restore that which we saved */
if (term)
rc |= setenv("TERM", term, 1);
if (display)
rc |= setenv("DISPLAY", display, 1);
if (xauthority)
rc |= setenv("XAUTHORITY", xauthority, 1);
rc |= setenv("HOME", pw->pw_dir, 1);
rc |= setenv("SHELL", pw->pw_shell, 1);
rc |= setenv("USER", pw->pw_name, 1);
rc |= setenv("LOGNAME", pw->pw_name, 1);
rc |= setenv("PATH", DEFAULT_PATH, 1);
out:
free(term);
free(display);
free(xauthority);
return rc;
}
/**
* This function will drop the capabilities so that we are left
* only with access to the audit system. If the user is root, we leave
* the capabilities alone since they already should have access to the
* audit netlink socket.
*
* Returns zero on success, non-zero otherwise
*/
#if defined(AUDIT_LOG_PRIV) && !defined(NAMESPACE_PRIV)
static int drop_capabilities(int full)
{
uid_t uid = getuid();
if (!uid) return 0;
capng_setpid(getpid());
capng_clear(CAPNG_SELECT_CAPS);
if (prctl(PR_SET_KEEPCAPS, 1, 0, 0, 0) < 0) {
fprintf(stderr, _("Error resetting KEEPCAPS, aborting\n"));
return -1;
}
/* Change uid */
if (setresuid(uid, uid, uid)) {
fprintf(stderr, _("Error changing uid, aborting.\n"));
return -1;
}
if (prctl(PR_SET_KEEPCAPS, 0, 0, 0, 0) < 0) {
fprintf(stderr, _("Error resetting KEEPCAPS, aborting\n"));
return -1;
}
if (! full)
capng_update(CAPNG_ADD, CAPNG_EFFECTIVE | CAPNG_PERMITTED, CAP_AUDIT_WRITE);
return capng_apply(CAPNG_SELECT_CAPS);
}
#elif defined(NAMESPACE_PRIV)
/**
* This function will drop the capabilities so that we are left
* only with access to the audit system and the ability to raise
* CAP_SYS_ADMIN, CAP_DAC_OVERRIDE, CAP_FOWNER and CAP_CHOWN,
* before invoking pam_namespace. These capabilities are needed
* for performing bind mounts/unmounts and to create potential new
* instance directories with appropriate DAC attributes. If the
* user is root, we leave the capabilities alone since they already
* should have access to the audit netlink socket and should have
* the ability to create/mount/unmount instance directories.
*
* Returns zero on success, non-zero otherwise
*/
static int drop_capabilities(int full)
{
uid_t uid = getuid();
if (!uid) return 0;
capng_setpid(getpid());
capng_clear(CAPNG_SELECT_CAPS);
if (prctl(PR_SET_KEEPCAPS, 1, 0, 0, 0) < 0) {
fprintf(stderr, _("Error resetting KEEPCAPS, aborting\n"));
return -1;
}
/* Change uid */
if (setresuid(uid, uid, uid)) {
fprintf(stderr, _("Error changing uid, aborting.\n"));
return -1;
}
if (prctl(PR_SET_KEEPCAPS, 0, 0, 0, 0) < 0) {
fprintf(stderr, _("Error resetting KEEPCAPS, aborting\n"));
return -1;
}
if (! full)
capng_updatev(CAPNG_ADD, CAPNG_EFFECTIVE | CAPNG_PERMITTED, CAP_SYS_ADMIN , CAP_FOWNER , CAP_CHOWN, CAP_DAC_OVERRIDE, CAP_AUDIT_WRITE, -1);
return capng_apply(CAPNG_SELECT_CAPS);
}
#else
static inline int drop_capabilities(__attribute__ ((__unused__)) int full)
{
return 0;
}
#endif
#ifdef NAMESPACE_PRIV
/**
* This function will set the uid values to be that of caller's uid, and
* will drop any privilages which maybe have been raised.
*/
static int transition_to_caller_uid()
{
uid_t uid = getuid();
if (prctl(PR_SET_KEEPCAPS, 0, 0, 0, 0) < 0) {
fprintf(stderr, _("Error resetting KEEPCAPS, aborting\n"));
return -1;
}
if (setresuid(uid, uid, uid)) {
fprintf(stderr, _("Error changing uid, aborting.\n"));
return -1;
}
return 0;
}
#endif
#ifdef AUDIT_LOG_PRIV
/* Send audit message */
static
int send_audit_message(int success, security_context_t old_context,
security_context_t new_context, const char *ttyn)
{
char *msg = NULL;
int rc;
int audit_fd = audit_open();
if (audit_fd < 0) {
fprintf(stderr, _("Error connecting to audit system.\n"));
return -1;
}
if (asprintf(&msg, "newrole: old-context=%s new-context=%s",
old_context ? old_context : "?",
new_context ? new_context : "?") < 0) {
fprintf(stderr, _("Error allocating memory.\n"));
rc = -1;
goto out;
}
rc = audit_log_user_message(audit_fd, AUDIT_USER_ROLE_CHANGE,
msg, NULL, NULL, ttyn, success);
if (rc <= 0) {
fprintf(stderr, _("Error sending audit message.\n"));
rc = -1;
goto out;
}
rc = 0;
out:
free(msg);
close(audit_fd);
return rc;
}
#else
static inline
int send_audit_message(int success __attribute__ ((unused)),
security_context_t old_context
__attribute__ ((unused)),
security_context_t new_context
__attribute__ ((unused)), const char *ttyn
__attribute__ ((unused)))
{
return 0;
}
#endif
/**
* This function attempts to relabel the tty. If this function fails, then
* the fd is closed, the contexts are free'd and -1 is returned. On success,
* a valid fd is returned and tty_context and new_tty_context are set.
*
* This function will not fail if it can not relabel the tty when selinux is
* in permissive mode.
*/
static int relabel_tty(const char *ttyn, security_context_t new_context,
security_context_t * tty_context,
security_context_t * new_tty_context)
{
int fd, rc;
int enforcing = security_getenforce();
security_context_t tty_con = NULL;
security_context_t new_tty_con = NULL;
if (!ttyn)
return 0;
if (enforcing < 0) {
fprintf(stderr, _("Could not determine enforcing mode.\n"));
return -1;
}
/* Re-open TTY descriptor */
fd = open(ttyn, O_RDWR | O_NONBLOCK);
if (fd < 0) {
fprintf(stderr, _("Error! Could not open %s.\n"), ttyn);
return fd;
}
/* this craziness is to make sure we cann't block on open and deadlock */
rc = fcntl(fd, F_SETFL, fcntl(fd, F_GETFL, 0) & ~O_NONBLOCK);
if (rc) {
fprintf(stderr, _("Error! Could not clear O_NONBLOCK on %s\n"), ttyn);
close(fd);
return rc;
}
if (fgetfilecon(fd, &tty_con) < 0) {
fprintf(stderr, _("%s! Could not get current context "
"for %s, not relabeling tty.\n"),
enforcing ? "Error" : "Warning", ttyn);
if (enforcing)
goto close_fd;
}
if (tty_con &&
(security_compute_relabel(new_context, tty_con,
string_to_security_class("chr_file"), &new_tty_con) < 0)) {
fprintf(stderr, _("%s! Could not get new context for %s, "
"not relabeling tty.\n"),
enforcing ? "Error" : "Warning", ttyn);
if (enforcing)
goto close_fd;
}
if (new_tty_con)
if (fsetfilecon(fd, new_tty_con) < 0) {
fprintf(stderr,
_("%s! Could not set new context for %s\n"),
enforcing ? "Error" : "Warning", ttyn);
freecon(new_tty_con);
new_tty_con = NULL;
if (enforcing)
goto close_fd;
}
*tty_context = tty_con;
*new_tty_context = new_tty_con;
return fd;
close_fd:
freecon(tty_con);
close(fd);
return -1;
}
/**
* This function attempts to revert the relabeling done to the tty.
* fd - referencing the opened ttyn
* ttyn - name of tty to restore
* tty_context - original context of the tty
* new_tty_context - context tty was relabeled to
*
* Returns zero on success, non-zero otherwise
*/
static int restore_tty_label(int fd, const char *ttyn,
security_context_t tty_context,
security_context_t new_tty_context)
{
int rc = 0;
security_context_t chk_tty_context = NULL;
if (!ttyn)
goto skip_relabel;
if (!new_tty_context)
goto skip_relabel;
/* Verify that the tty still has the context set by newrole. */
if ((rc = fgetfilecon(fd, &chk_tty_context)) < 0) {
fprintf(stderr, "Could not fgetfilecon %s.\n", ttyn);
goto skip_relabel;
}
if ((rc = strcmp(chk_tty_context, new_tty_context))) {
fprintf(stderr, _("%s changed labels.\n"), ttyn);
goto skip_relabel;
}
if ((rc = fsetfilecon(fd, tty_context)) < 0)
fprintf(stderr,
_("Warning! Could not restore context for %s\n"), ttyn);
skip_relabel:
freecon(chk_tty_context);
return rc;
}
/**
* Parses and validates the provided command line options and
* constructs a new context based on our old context and the
* arguments specified on the command line. On success
* new_context will be set to valid values, otherwise its value
* is left unchanged.
*
* Returns zero on success, non-zero otherwise.
*/
static int parse_command_line_arguments(int argc, char **argv, char *ttyn,
security_context_t old_context,
security_context_t * new_context,
int *preserve_environment)
{
int flag_index; /* flag index in argv[] */
int clflag; /* holds codes for command line flags */
char *role_s = NULL; /* role spec'd by user in argv[] */
char *type_s = NULL; /* type spec'd by user in argv[] */
char *type_ptr = NULL; /* stores malloc'd data from get_default_type */
char *level_s = NULL; /* level spec'd by user in argv[] */
char *range_ptr = NULL;
security_context_t new_con = NULL;
security_context_t tty_con = NULL;
context_t context = NULL; /* manipulatable form of new_context */
const struct option long_options[] = {
{"role", 1, 0, 'r'},
{"type", 1, 0, 't'},
{"level", 1, 0, 'l'},
{"preserve-environment", 0, 0, 'p'},
{"version", 0, 0, 'V'},
{NULL, 0, 0, 0}
};
*preserve_environment = 0;
while (1) {
clflag = getopt_long(argc, argv, "r:t:l:pV", long_options,
&flag_index);
if (clflag == -1)
break;
switch (clflag) {
case 'V':
printf("newrole: %s version %s\n", PACKAGE, VERSION);
exit(0);
break;
case 'p':
*preserve_environment = 1;
break;
case 'r':
if (role_s) {
fprintf(stderr,
_("Error: multiple roles specified\n"));
return -1;
}
role_s = optarg;
break;
case 't':
if (type_s) {
fprintf(stderr,
_("Error: multiple types specified\n"));
return -1;
}
type_s = optarg;
break;
case 'l':
if (!is_selinux_mls_enabled()) {
fprintf(stderr, _("Sorry, -l may be used with "
"SELinux MLS support.\n"));
return -1;
}
if (level_s) {
fprintf(stderr, _("Error: multiple levels "
"specified\n"));
return -1;
}
if (ttyn) {
if (fgetfilecon(STDIN_FILENO, &tty_con) >= 0) {
if (selinux_check_securetty_context
(tty_con) < 0) {
fprintf(stderr,
_
("Error: you are not allowed to change levels on a non secure terminal \n"));
freecon(tty_con);
return -1;
}
freecon(tty_con);
}
}
level_s = optarg;
break;
default:
fprintf(stderr, "%s\n", USAGE_STRING);
return -1;
}
}
/* Verify that the combination of command-line arguments are viable */
if (!(role_s || type_s || level_s)) {
fprintf(stderr, "%s\n", USAGE_STRING);
return -1;
}
/* Fill in a default type if one hasn't been specified. */
if (role_s && !type_s) {
/* get_default_type() returns malloc'd memory */
if (get_default_type(role_s, &type_ptr)) {
fprintf(stderr, _("Couldn't get default type.\n"));
send_audit_message(0, old_context, new_con, ttyn);
return -1;
}
type_s = type_ptr;
}
/* Create a temporary new context structure we extract and modify */
context = context_new(old_context);
if (!context) {
fprintf(stderr, _("failed to get new context.\n"));
goto err_free;
}
/* Modify the temporary new context */
if (role_s)
if (context_role_set(context, role_s)) {
fprintf(stderr, _("failed to set new role %s\n"),
role_s);
goto err_free;
}
if (type_s)
if (context_type_set(context, type_s)) {
fprintf(stderr, _("failed to set new type %s\n"),
type_s);
goto err_free;
}
if (level_s) {
range_ptr =
build_new_range(level_s, context_range_get(context));
if (!range_ptr) {
fprintf(stderr,
_("failed to build new range with level %s\n"),
level_s);
goto err_free;
}
if (context_range_set(context, range_ptr)) {
fprintf(stderr, _("failed to set new range %s\n"),
range_ptr);
goto err_free;
}
}
/* Construct the final new context */
if (!(new_con = context_str(context))) {
fprintf(stderr, _("failed to convert new context to string\n"));
goto err_free;
}
if (security_check_context(new_con) < 0) {
fprintf(stderr, _("%s is not a valid context\n"), new_con);
send_audit_message(0, old_context, new_con, ttyn);
goto err_free;
}
*new_context = strdup(new_con);
if (!*new_context) {
fprintf(stderr, _("Unable to allocate memory for new_context"));
goto err_free;
}
free(type_ptr);
free(range_ptr);
context_free(context);
return 0;
err_free:
free(type_ptr);
free(range_ptr);
/* Don't free new_con, context_free(context) handles this */
context_free(context);
return -1;
}
/**
* Take care of any signal setup
*/
static int set_signal_handles(void)
{
sigset_t empty;
/* Empty the signal mask in case someone is blocking a signal */
if (sigemptyset(&empty)) {
fprintf(stderr, _("Unable to obtain empty signal set\n"));
return -1;
}
(void)sigprocmask(SIG_SETMASK, &empty, NULL);
/* Terminate on SIGHUP. */
if (signal(SIGHUP, SIG_DFL) == SIG_ERR) {
fprintf(stderr, _("Unable to set SIGHUP handler\n"));
return -1;
}
return 0;
}
/************************************************************************
*
* All code used for both PAM and shadow passwd goes in this section.
*
************************************************************************/
int main(int argc, char *argv[])
{
security_context_t new_context = NULL; /* target security context */
security_context_t old_context = NULL; /* original securiy context */
security_context_t tty_context = NULL; /* current context of tty */
security_context_t new_tty_context = NULL; /* new context of tty */
struct passwd pw; /* struct derived from passwd file line */
char *ttyn = NULL; /* tty path */
char **old_environ;
int preserve_environment;
int fd;
pid_t childPid = 0;
char *shell_argv0 = NULL;
int rc;
#ifdef USE_PAM
int pam_status; /* pam return code */
pam_handle_t *pam_handle; /* opaque handle used by all PAM functions */
/* This is a jump table of functions for PAM to use when it wants to *
* communicate with the user. We'll be using misc_conv(), which is *
* provided for us via pam_misc.h. */
struct pam_conv pam_conversation = {
misc_conv,
NULL
};
#endif
/*
* Step 0: Setup
*
* Do some intial setup, including dropping capabilities, checking
* if it makes sense to continue to run newrole, and setting up
* a scrubbed environment.
*/
if (drop_capabilities(FALSE)) {
perror(_("Sorry, newrole failed to drop capabilities\n"));
return -1;
}
if (set_signal_handles())
return -1;
#ifdef USE_NLS
setlocale(LC_ALL, "");
bindtextdomain(PACKAGE, LOCALEDIR);
textdomain(PACKAGE);
#endif
old_environ = environ;
environ = NULL;
if (!is_selinux_enabled()) {
fprintf(stderr, _("Sorry, newrole may be used only on "
"a SELinux kernel.\n"));
return -1;
}
if (security_getenforce() < 0) {
fprintf(stderr, _("Could not determine enforcing mode.\n"));
return -1;
}
/*
* Step 1: Parse command line and valid arguments
*
* old_context and ttyn are required for audit logging,
* context validation and pam
*/
if (getprevcon(&old_context)) {
fprintf(stderr, _("failed to get old_context.\n"));
return -1;
}
ttyn = ttyname(STDIN_FILENO);
if (!ttyn || *ttyn == '\0') {
fprintf(stderr,
_("Warning! Could not retrieve tty information.\n"));
}
if (parse_command_line_arguments(argc, argv, ttyn, old_context,
&new_context, &preserve_environment))
return -1;
/*
* Step 2: Authenticate the user.
*
* Re-authenticate the user running this program.
* This is just to help confirm user intent (vs. invocation by
* malicious software), not to authorize the operation (which is covered
* by policy). Trusted path mechanism would be preferred.
*/
memset(&pw, 0, sizeof(pw));
if (extract_pw_data(&pw))
goto err_free;
#ifdef USE_PAM
if (read_pam_config()) {
fprintf(stderr,
_("error on reading PAM service configuration.\n"));
goto err_free;
}
if (app_service_names != NULL && optind < argc) {
if (strcmp(argv[optind], "-c") == 0 && optind < (argc - 1)) {
/*
* Check for a separate pam service name for the
* command when invoked by newrole.
*/
char *cmd = NULL;
rc = sscanf(argv[optind + 1], "%ms", &cmd);
if (rc != EOF && cmd) {
char *app_service_name =
(char *)hashtab_search(app_service_names,
cmd);
free(cmd);
if (app_service_name != NULL)
service_name = app_service_name;
}
}
}
pam_status = pam_start(service_name, pw.pw_name, &pam_conversation,
&pam_handle);
if (pam_status != PAM_SUCCESS) {
fprintf(stderr, _("failed to initialize PAM\n"));
goto err_free;
}
if (!authenticate_via_pam(ttyn, pam_handle))
#else
if (!authenticate_via_shadow_passwd(pw.pw_name))
#endif
{
fprintf(stderr, _("newrole: incorrect password for %s\n"),
pw.pw_name);
send_audit_message(0, old_context, new_context, ttyn);
goto err_close_pam;
}
/*
* Step 3: Handle relabeling of the tty.
*
* Once we authenticate the user, we know that we want to proceed with
* the action. Prior to this point, no changes are made the to system.
*/
fd = relabel_tty(ttyn, new_context, &tty_context, &new_tty_context);
if (fd < 0)
goto err_close_pam;
/*
* Step 4: Fork
*
* Fork, allowing parent to clean up after shell has executed.
* Child: reopen stdin, stdout, stderr and exec shell
* Parnet: wait for child to die and restore tty's context
*/
childPid = fork();
if (childPid < 0) {
/* fork failed, no child to worry about */
int errsv = errno;
fprintf(stderr, _("newrole: failure forking: %s"),
strerror(errsv));
if (restore_tty_label(fd, ttyn, tty_context, new_tty_context))
fprintf(stderr, _("Unable to restore tty label...\n"));
if (close(fd))
fprintf(stderr, _("Failed to close tty properly\n"));
goto err_close_pam;
} else if (childPid) {
/* PARENT
* It doesn't make senes to exit early on errors at this point,
* since we are doing cleanup which needs to be done.
* We can exit with a bad rc though
*/
pid_t pid;
int exit_code = 0;
int status;
do {
pid = wait(&status);
} while (pid < 0 && errno == EINTR);
/* Preserve child exit status, unless there is another error. */
if (WIFEXITED(status))
exit_code = WEXITSTATUS(status);
if (restore_tty_label(fd, ttyn, tty_context, new_tty_context)) {
fprintf(stderr, _("Unable to restore tty label...\n"));
exit_code = -1;
}
freecon(tty_context);
freecon(new_tty_context);
if (close(fd)) {
fprintf(stderr, _("Failed to close tty properly\n"));
exit_code = -1;
}
#ifdef USE_PAM
#ifdef NAMESPACE_PRIV
pam_status = pam_close_session(pam_handle, 0);
if (pam_status != PAM_SUCCESS) {
fprintf(stderr, "pam_close_session failed with %s\n",
pam_strerror(pam_handle, pam_status));
exit_code = -1;
}
#endif
rc = pam_end(pam_handle, pam_status);
if (rc != PAM_SUCCESS) {
fprintf(stderr, "pam_end failed with %s\n",
pam_strerror(pam_handle, rc));
exit_code = -1;
}
hashtab_map(app_service_names, free_hashtab_entry, NULL);
hashtab_destroy(app_service_names);
#endif
free(pw.pw_name);
free(pw.pw_dir);
free(pw.pw_shell);
free(shell_argv0);
return exit_code;
}
/* CHILD */
/* Close the tty and reopen descriptors 0 through 2 */
if (ttyn) {
if (close(fd) || close(0) || close(1) || close(2)) {
fprintf(stderr, _("Could not close descriptors.\n"));
goto err_close_pam;
}
fd = open(ttyn, O_RDWR | O_NONBLOCK);
if (fd != 0)
goto err_close_pam;
rc = fcntl(fd, F_SETFL, fcntl(fd, F_GETFL, 0) & ~O_NONBLOCK);
if (rc)
goto err_close_pam;
fd = open(ttyn, O_RDWR | O_NONBLOCK);
if (fd != 1)
goto err_close_pam;
rc = fcntl(fd, F_SETFL, fcntl(fd, F_GETFL, 0) & ~O_NONBLOCK);
if (rc)
goto err_close_pam;
fd = open(ttyn, O_RDWR | O_NONBLOCK);
if (fd != 2)
goto err_close_pam;
rc = fcntl(fd, F_SETFL, fcntl(fd, F_GETFL, 0) & ~O_NONBLOCK);
if (rc)
goto err_close_pam;
}
/*
* Step 5: Execute a new shell with the new context in `new_context'.
*
* Establish context, namesapce and any options for the new shell
*/
if (optind < 1)
optind = 1;
/* This is ugly, but use newrole's argv for the exec'd shells argv */
if (asprintf(&shell_argv0, "-%s", pw.pw_shell) < 0) {
fprintf(stderr, _("Error allocating shell's argv0.\n"));
shell_argv0 = NULL;
goto err_close_pam;
}
argv[optind - 1] = shell_argv0;
if (setexeccon(new_context)) {
fprintf(stderr, _("Could not set exec context to %s.\n"),
new_context);
goto err_close_pam;
}
#ifdef NAMESPACE_PRIV
/* Ask PAM to setup session for user running this program */
pam_status = pam_open_session(pam_handle, 0);
if (pam_status != PAM_SUCCESS) {
fprintf(stderr, "pam_open_session failed with %s\n",
pam_strerror(pam_handle, pam_status));
goto err_close_pam;
}
#endif
if (send_audit_message(1, old_context, new_context, ttyn)) {
fprintf(stderr, _("Failed to send audit message"));
goto err_close_pam_session;
}
freecon(old_context); old_context=NULL;
freecon(new_context); new_context=NULL;
#ifdef NAMESPACE_PRIV
if (transition_to_caller_uid()) {
fprintf(stderr, _("Failed to transition to namespace\n"));
goto err_close_pam_session;
}
#endif
if (drop_capabilities(TRUE)) {
fprintf(stderr, _("Failed to drop capabilities %m\n"));
goto err_close_pam_session;
}
/* Handle environment changes */
if (restore_environment(preserve_environment, old_environ, &pw)) {
fprintf(stderr, _("Unable to restore the environment, "
"aborting\n"));
goto err_close_pam_session;
}
execv(pw.pw_shell, argv + optind - 1);
/*
* Error path cleanup
*
* If we reach here, then we failed to exec the new shell.
*/
perror(_("failed to exec shell\n"));
err_close_pam_session:
#ifdef NAMESPACE_PRIV
pam_status = pam_close_session(pam_handle, 0);
if (pam_status != PAM_SUCCESS)
fprintf(stderr, "pam_close_session failed with %s\n",
pam_strerror(pam_handle, pam_status));
#endif
err_close_pam:
#ifdef USE_PAM
rc = pam_end(pam_handle, pam_status);
if (rc != PAM_SUCCESS)
fprintf(stderr, "pam_end failed with %s\n",
pam_strerror(pam_handle, rc));
#endif
err_free:
freecon(tty_context);
freecon(new_tty_context);
freecon(old_context);
freecon(new_context);
free(pw.pw_name);
free(pw.pw_dir);
free(pw.pw_shell);
free(shell_argv0);
#ifdef USE_PAM
if (app_service_names) {
hashtab_map(app_service_names, free_hashtab_entry, NULL);
hashtab_destroy(app_service_names);
}
#endif
return -1;
} /* main() */
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