mirror of
https://github.com/SELinuxProject/selinux
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4be2fd4576
If /usr/sbin/open_init_pty is not found or is not executable,
access("/usr/sbin/open_init_pty", X_OK) returns -1, not zero.
Use "!= 0" like in other places in SELinux userland libraries and tools.
431 lines
12 KiB
C
431 lines
12 KiB
C
/************************************************************************
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*
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* run_init
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*
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* SYNOPSIS:
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*
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* This program allows a user to run an /etc/init.d script in the proper context.
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*
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* USAGE:
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*
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* run_init <script> <args>
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*
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* BUILD OPTIONS:
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*
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* option USE_PAM:
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*
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* Set the USE_PAM constant if you want to authenticate users via PAM.
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* If USE_PAM is not set, users will be authenticated via direct
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* access to the shadow password file.
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*
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* If you decide to use PAM must be told how to handle run_init. A
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* good rule-of-thumb might be to tell PAM to handle run_init in the
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* same way it handles su, except that you should remove the pam_rootok.so
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* entry so that even root must re-authenticate to run the init scripts
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* in the proper context.
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*
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* If you choose not to use PAM, make sure you have a shadow passwd file
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* in /etc/shadow. You can use a simlink if your shadow passwd file
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* lives in another directory. Example:
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* su
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* cd /etc
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* ln -s /etc/auth/shadow shadow
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*
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* If you decide not to use PAM, you will also have to make run_init
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* setuid root, so that it can read the shadow passwd file.
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*
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*
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*************************************************************************/
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#include <stdio.h>
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#include <stdlib.h> /* for malloc(), realloc(), free() */
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#include <pwd.h> /* for getpwuid() */
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#include <sys/types.h> /* to make getuid() and getpwuid() happy */
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#include <sys/wait.h> /* for wait() */
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#include <sys/stat.h> /* for struct stat and friends */
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#include <getopt.h> /* for getopt_long() form of getopt() */
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#include <selinux/selinux.h>
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#include <selinux/get_default_type.h>
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#include <selinux/context.h> /* for context-mangling functions */
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#include <fcntl.h>
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#include <ctype.h>
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#include <limits.h>
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#ifdef USE_AUDIT
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#include <libaudit.h>
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#endif
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#ifdef USE_NLS
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#include <libintl.h>
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#include <locale.h>
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#define _(msgid) gettext (msgid)
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#else
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#define _(msgid) (msgid)
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#endif
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#ifndef PACKAGE
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#define PACKAGE "policycoreutils" /* the name of this package lang translation */
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#endif
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/* USAGE_STRING describes the command-line args of this program. */
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#define USAGE_STRING _("USAGE: run_init <script> <args ...>\n\
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where: <script> is the name of the init script to run,\n\
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<args ...> are the arguments to that script.")
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#define CONTEXT_FILE "initrc_context"
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#ifdef USE_PAM
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/************************************************************************
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*
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* All PAM code goes in this section.
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*
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************************************************************************/
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#include <unistd.h> /* for getuid(), exit(), getopt() */
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#include <security/pam_appl.h> /* for PAM functions */
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#include <security/pam_misc.h> /* for misc_conv PAM utility function */
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#define SERVICE_NAME "run_init" /* the name of this program for PAM */
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/* The file containing the context to run
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* the scripts under. */
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int authenticate_via_pam(const struct passwd *);
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/* authenticate_via_pam()
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*
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* in: p_passwd_line - struct containing data from our user's line in
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* the passwd file.
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* out: nothing
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* return: value condition
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* ----- ---------
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* 1 PAM thinks that the user authenticated themselves properly
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* 0 otherwise
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*
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* This function uses PAM to authenticate the user running this
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* program. This is the only function in this program that makes PAM
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* calls.
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*
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*/
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int authenticate_via_pam(const struct passwd *p_passwd_line)
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{
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int result = 0; /* our result, set to 0 (not authenticated) by default */
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pam_handle_t *pam_handle; /* opaque handle used by all PAM functions */
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/* This is a jump table of functions for PAM to use when it wants to *
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* communicate with the user. We'll be using misc_conv(), which is *
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* provided for us via pam_misc.h. */
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struct pam_conv pam_conversation = {
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misc_conv,
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NULL
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};
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/* Make `p_pam_handle' a valid PAM handle so we can use it when *
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* calling PAM functions. */
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if (PAM_SUCCESS != pam_start(SERVICE_NAME,
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p_passwd_line->pw_name,
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&pam_conversation, &pam_handle)) {
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fprintf(stderr, _("failed to initialize PAM\n"));
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exit(-1);
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}
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/* Ask PAM to authenticate the user running this program */
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if (PAM_SUCCESS == pam_authenticate(pam_handle, 0)) {
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result = 1; /* user authenticated OK! */
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}
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/* If we were successful, call pam_acct_mgmt() to reset the
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* pam_tally failcount.
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*/
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if (result && (PAM_SUCCESS != pam_acct_mgmt(pam_handle, 0)) ) {
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fprintf(stderr, _("failed to get account information\n"));
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exit(-1);
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}
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/* We're done with PAM. Free `pam_handle'. */
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pam_end(pam_handle, PAM_SUCCESS);
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return (result);
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} /* authenticate_via_pam() */
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#else /* else !USE_PAM */
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/************************************************************************
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*
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* All shadow passwd code goes in this section.
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*
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************************************************************************/
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#include <unistd.h> /* for getuid(), exit(), crypt() */
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#include <shadow.h> /* for shadow passwd functions */
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#include <string.h> /* for strlen(), memset() */
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#define PASSWORD_PROMPT _("Password:") /* prompt for getpass() */
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int authenticate_via_shadow_passwd(const struct passwd *);
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/* authenticate_via_shadow_passwd()
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*
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* in: p_passwd_line - struct containing data from our user's line in
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* the passwd file.
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* out: nothing
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* return: value condition
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* ----- ---------
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* 1 user authenticated themselves properly according to the
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* shadow passwd file.
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* 0 otherwise
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*
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* This function uses the shadow passwd file to authenticate the user running
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* this program.
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*
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*/
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int authenticate_via_shadow_passwd(const struct passwd *p_passwd_line)
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{
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struct spwd *p_shadow_line; /* struct derived from shadow passwd file line */
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char *unencrypted_password_s; /* unencrypted password input by user */
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char *encrypted_password_s; /* user's password input after being crypt()ed */
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/* Make `p_shadow_line' point to the data from the current user's *
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* line in the shadow passwd file. */
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setspent(); /* Begin access to the shadow passwd file. */
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p_shadow_line = getspnam(p_passwd_line->pw_name);
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endspent(); /* End access to the shadow passwd file. */
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if (!(p_shadow_line)) {
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fprintf(stderr,
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_
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("Cannot find your entry in the shadow passwd file.\n"));
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exit(-1);
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}
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/* Ask user to input unencrypted password */
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if (!(unencrypted_password_s = getpass(PASSWORD_PROMPT))) {
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fprintf(stderr, _("getpass cannot open /dev/tty\n"));
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exit(-1);
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}
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/* Use crypt() to encrypt user's input password. Clear the *
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* unencrypted password as soon as we're done, so it is not *
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* visible to memory snoopers. */
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encrypted_password_s = crypt(unencrypted_password_s,
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p_shadow_line->sp_pwdp);
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memset(unencrypted_password_s, 0, strlen(unencrypted_password_s));
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/* Return 1 (authenticated) iff the encrypted version of the user's *
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* input password matches the encrypted password stored in the *
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* shadow password file. */
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return (!strcmp(encrypted_password_s, p_shadow_line->sp_pwdp));
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} /* authenticate_via_shadow_passwd() */
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#endif /* if/else USE_PAM */
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/*
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* authenticate_user()
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*
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* Authenticate the user.
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*
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* in: nothing
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* out: nothing
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* return: 0 When success
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* -1 When failure
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*/
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int authenticate_user(void)
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{
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#define INITLEN 255
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struct passwd *p_passwd_line; /* struct derived from passwd file line */
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uid_t uid;
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/*
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* Determine the Linux user identity to re-authenticate.
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* If supported and set, use the login uid, as this should be more stable.
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* Otherwise, use the real uid.
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* The SELinux user identity is no longer used, as Linux users are now
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* mapped to SELinux users via seusers and the SELinux user identity space
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* is separate.
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*/
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#ifdef USE_AUDIT
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uid = audit_getloginuid();
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if (uid == (uid_t) - 1)
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uid = getuid();
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#else
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uid = getuid();
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#endif
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p_passwd_line = getpwuid(uid);
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if (!p_passwd_line) {
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fprintf(stderr, "cannot find your entry in the passwd file.\n");
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return (-1);
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}
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printf("Authenticating %s.\n", p_passwd_line->pw_name);
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/*
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* Re-authenticate the user running this program.
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* This is just to help confirm user intent (vs. invocation by
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* malicious software), not to authorize the operation (which is covered
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* by policy). Trusted path mechanism would be preferred.
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*/
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#ifdef USE_PAM
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if (!authenticate_via_pam(p_passwd_line)) {
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#else /* !USE_PAM */
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if (!authenticate_via_shadow_passwd(p_passwd_line)) {
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#endif /* if/else USE_PAM */
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fprintf(stderr, _("run_init: incorrect password for %s\n"),
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p_passwd_line->pw_name);
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return (-1);
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}
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/* If we reach here, then we have authenticated the user. */
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#ifdef CANTSPELLGDB
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printf("You are authenticated!\n");
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#endif
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return 0;
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} /* authenticate_user() */
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/*
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* get_init_context()
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*
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* Get the CONTEXT associated with the context for the init scripts. *
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*
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* in: nothing
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* out: The CONTEXT associated with the context.
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* return: 0 on success, -1 on failure.
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*/
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int get_init_context(security_context_t * context)
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{
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FILE *fp;
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char buf[255], *bufp;
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int buf_len;
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char context_file[PATH_MAX];
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snprintf(context_file, sizeof(context_file) - 1, "%s/%s",
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selinux_contexts_path(), CONTEXT_FILE);
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fp = fopen(context_file, "r");
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if (!fp) {
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fprintf(stderr, _("Could not open file %s\n"), context_file);
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return -1;
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}
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while (1) { /* loop until we find a non-empty line */
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if (!fgets(buf, sizeof buf, fp))
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break;
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buf_len = strlen(buf);
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if (buf[buf_len - 1] == '\n')
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buf[buf_len - 1] = 0;
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bufp = buf;
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while (*bufp && isspace(*bufp))
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bufp++;
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if (*bufp) {
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*context = strdup(bufp);
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if (!(*context))
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goto out;
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fclose(fp);
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return 0;
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}
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}
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out:
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fclose(fp);
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fprintf(stderr, _("No context in file %s\n"), context_file);
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return -1;
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} /* get_init_context() */
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/*****************************************************************************
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* main() *
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*****************************************************************************/
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int main(int argc, char *argv[])
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{
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extern char *optarg; /* used by getopt() for arg strings */
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extern int opterr; /* controls getopt() error messages */
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security_context_t new_context; /* context for the init script context */
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#ifdef USE_NLS
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setlocale(LC_ALL, "");
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bindtextdomain(PACKAGE, LOCALEDIR);
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textdomain(PACKAGE);
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#endif
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/* Verify that we are running on a flask-enabled kernel. */
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if (!is_selinux_enabled()) {
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fprintf(stderr,
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_
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("Sorry, run_init may be used only on a SELinux kernel.\n"));
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exit(-1);
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}
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/*
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* Step 1: Handle command-line arguments. The first argument is the
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* name of the script to run. All other arguments are for the script
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* itself, and will be passed directly to the script.
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*/
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if (argc < 2) {
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fprintf(stderr, "%s\n", USAGE_STRING);
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exit(-1);
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}
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/*
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* Step 2: Authenticate the user.
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*/
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if (authenticate_user() != 0) {
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fprintf(stderr, _("authentication failed.\n"));
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exit(-1);
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}
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/*
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* Step 3: Get the context for the script to be run in.
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*/
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if (get_init_context(&new_context) == 0) {
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#ifdef CANTSPELLGDB
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printf("context is %s\n", new_context);
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#endif
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} else {
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exit(-1);
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}
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/*
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* Step 4: Run the command in the correct context.
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*/
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if (chdir("/")) {
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perror("chdir");
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exit(-1);
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}
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if (setexeccon(new_context) < 0) {
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fprintf(stderr, _("Could not set exec context to %s.\n"),
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new_context);
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exit(-1);
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}
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if (access("/usr/sbin/open_init_pty", X_OK) != 0) {
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if (execvp(argv[1], argv + 1)) {
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perror("execvp");
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exit(-1);
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}
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return 0;
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}
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/*
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* Do not execvp the command directly from run_init; since it would run
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* under with a pty under sysadm_devpts_t. Instead, we call open_init_tty,
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* which transitions us into initrc_t, which then spawns a new
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* process, that gets a pty with context initrc_devpts_t. Just
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* execvp or using a exec(1) recycles pty's, and does not open a new
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* one.
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*/
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if (execvp("/usr/sbin/open_init_pty", argv)) {
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perror("execvp");
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exit(-1);
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}
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return 0;
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} /* main() */
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