coreutils/coreutils-pam.patch

diff -urNp coreutils-8.0-orig/configure.ac coreutils-8.0/configure.ac
--- coreutils-8.0-orig/configure.ac	2009-09-29 15:27:11.000000000 +0200
+++ coreutils-8.0/configure.ac	2009-10-07 10:04:27.000000000 +0200
@@ -115,6 +115,13 @@ if test "$gl_gcc_warnings" = yes; then
   AC_DEFINE([GNULIB_PORTCHECK], [1], [enable some gnulib portability checks])
 fi
 
+dnl Give the chance to enable PAM
+AC_ARG_ENABLE(pam, dnl
+[  --enable-pam              Enable use of the PAM libraries],
+[AC_DEFINE(USE_PAM, 1, [Define if you want to use PAM])
+LIB_PAM="-ldl -lpam -lpam_misc"
+AC_SUBST(LIB_PAM)])
+
 AC_FUNC_FORK
 
 optional_bin_progs=
diff -urNp coreutils-8.0-orig/doc/coreutils.texi coreutils-8.0/doc/coreutils.texi
--- coreutils-8.0-orig/doc/coreutils.texi	2009-09-29 15:27:54.000000000 +0200
+++ coreutils-8.0/doc/coreutils.texi	2009-10-07 10:04:27.000000000 +0200
@@ -14742,8 +14742,11 @@ to certain shells, etc.).
 @findex syslog
 @command{su} can optionally be compiled to use @code{syslog} to report
 failed, and optionally successful, @command{su} attempts.  (If the system
-supports @code{syslog}.)  However, GNU @command{su} does not check if the
-user is a member of the @code{wheel} group; see below.
+supports @code{syslog}.)
+
+This version of @command{su} has support for using PAM for
+authentication.  You can edit @file{/etc/pam.d/su} to customize its
+behaviour.
 
 The program accepts the following options.  Also see @ref{Common options}.
 
@@ -14785,6 +14788,8 @@ environment variables except @env{TERM},
 @env{PATH} to a compiled-in default value.  Change to @var{user}'s home
 directory.  Prepend @samp{-} to the shell's name, intended to make it
 read its login startup file(s).
+Additionaly @env{DISPLAY} and @env{XAUTHORITY} environment variables 
+are preserved as well for PAM functionality.
 
 @item -m
 @itemx -p
@@ -14824,33 +14829,6 @@ Exit status:
 the exit status of the subshell otherwise
 @end display
 
-@cindex wheel group, not supported
-@cindex group wheel, not supported
-@cindex fascism
-@subsection Why GNU @command{su} does not support the @samp{wheel} group
-
-(This section is by Richard Stallman.)
-
-@cindex Twenex
-@cindex MIT AI lab
-Sometimes a few of the users try to hold total power over all the
-rest.  For example, in 1984, a few users at the MIT AI lab decided to
-seize power by changing the operator password on the Twenex system and
-keeping it secret from everyone else.  (I was able to thwart this coup
-and give power back to the users by patching the kernel, but I
-wouldn't know how to do that in Unix.)
-
-However, occasionally the rulers do tell someone.  Under the usual
-@command{su} mechanism, once someone learns the root password who
-sympathizes with the ordinary users, he or she can tell the rest.  The
-``wheel group'' feature would make this impossible, and thus cement the
-power of the rulers.
-
-I'm on the side of the masses, not that of the rulers.  If you are
-used to supporting the bosses and sysadmins in whatever they do, you
-might find this idea strange at first.
-
-
 @node timeout invocation
 @section @command{timeout}: Run a command with a time limit
 
diff -urNp coreutils-8.0-orig/src/Makefile.am coreutils-8.0/src/Makefile.am
--- coreutils-8.0-orig/src/Makefile.am	2009-09-21 14:29:33.000000000 +0200
+++ coreutils-8.0/src/Makefile.am	2009-10-07 10:04:27.000000000 +0200
@@ -154,7 +154,7 @@ tail_LDADD = $(nanosec_libs)
 # If necessary, add -lm to resolve use of pow in lib/strtod.c.
 uptime_LDADD = $(LDADD) $(POW_LIB) $(GETLOADAVG_LIBS)
 
-su_LDADD = $(LDADD) $(LIB_CRYPT)
+su_LDADD = $(LDADD) $(LIB_CRYPT) @LIB_PAM@
 
 dir_LDADD += $(LIB_ACL)
 ls_LDADD += $(LIB_ACL)
diff -urNp coreutils-8.0-orig/src/su.c coreutils-8.0/src/su.c
--- coreutils-8.0-orig/src/su.c	2009-10-07 10:03:29.000000000 +0200
+++ coreutils-8.0/src/su.c	2009-10-07 10:04:27.000000000 +0200
@@ -37,6 +37,16 @@
    restricts who can su to UID 0 accounts.  RMS considers that to
    be fascist.
 
+#ifdef USE_PAM
+
+   Actually, with PAM, su has nothing to do with whether or not a
+   wheel group is enforced by su.  RMS tries to restrict your access
+   to a su which implements the wheel group, but PAM considers that
+   to be fascist, and gives the user/sysadmin the opportunity to
+   enforce a wheel group by proper editing of /etc/pam.conf
+
+#endif
+
    Compile-time options:
    -DSYSLOG_SUCCESS	Log successful su's (by default, to root) with syslog.
    -DSYSLOG_FAILURE	Log failed su's (by default, to root) with syslog.
@@ -53,6 +63,15 @@
 #include <pwd.h>
 #include <grp.h>
 
+#ifdef USE_PAM
+# include <signal.h>
+# include <sys/wait.h>
+# include <sys/fsuid.h>
+# include <unistd.h>
+# include <security/pam_appl.h>
+# include <security/pam_misc.h>
+#endif /* USE_PAM */
+
 #include "system.h"
 #include "getpass.h"
 
@@ -120,12 +139,19 @@
 /* The user to become if none is specified.  */
 #define DEFAULT_USER "root"
 
+#ifndef USE_PAM
 char *crypt (char const *key, char const *salt);
+#endif
 
 extern char **environ;
 
-static void run_shell (char const *, char const *, char **, size_t)
+static void run_shell (char const *, char const *, char **, size_t,
+	const struct passwd *)
+#ifdef USE_PAM
+	;
+#else
      ATTRIBUTE_NORETURN;
+#endif
 
 /* If true, pass the `-f' option to the subshell.  */
 static bool fast_startup;
@@ -211,7 +237,26 @@ log_su (struct passwd const *pw, bool su
 }
 #endif
 
+#ifdef USE_PAM
+static pam_handle_t *pamh = NULL;
+static int retval;
+static struct pam_conv conv = {
+  misc_conv,
+  NULL
+};
+
+#define PAM_BAIL_P if (retval) { \
+  pam_end(pamh, PAM_SUCCESS); \
+  return 0; \
+}
+#define PAM_BAIL_P_VOID if (retval) {		\
+  pam_end(pamh, PAM_SUCCESS);			\
+return;						\
+}
+#endif
+
 /* Ask the user for a password.
+   If PAM is in use, let PAM ask for the password if necessary.
    Return true if the user gives the correct password for entry PW,
    false if not.  Return true without asking for a password if run by UID 0
    or if PW has an empty password.  */
@@ -219,6 +264,44 @@ log_su (struct passwd const *pw, bool su
 static bool
 correct_password (const struct passwd *pw)
 {
+#ifdef USE_PAM
+  struct passwd *caller;
+  char *tty_name, *ttyn;
+  retval = pam_start(PROGRAM_NAME, pw->pw_name, &conv, &pamh);
+  PAM_BAIL_P;
+
+  if (getuid() != 0 && !isatty(0)) {
+	fprintf(stderr, "standard in must be a tty\n");
+	exit(1);
+  }
+
+  caller = getpwuid(getuid());
+  if(caller != NULL && caller->pw_name != NULL) {
+	  retval = pam_set_item(pamh, PAM_RUSER, caller->pw_name);
+	  PAM_BAIL_P;
+  }
+
+  ttyn = ttyname(0);
+  if (ttyn) {
+    if (strncmp(ttyn, "/dev/", 5) == 0)
+       tty_name = ttyn+5;
+    else
+       tty_name = ttyn;
+    retval = pam_set_item(pamh, PAM_TTY, tty_name);
+    PAM_BAIL_P;
+  }
+  retval = pam_authenticate(pamh, 0);
+  PAM_BAIL_P;
+  retval = pam_acct_mgmt(pamh, 0);
+  if (retval == PAM_NEW_AUTHTOK_REQD) {
+    /* password has expired.  Offer option to change it. */
+    retval = pam_chauthtok(pamh, PAM_CHANGE_EXPIRED_AUTHTOK);
+    PAM_BAIL_P;
+  }
+  PAM_BAIL_P;
+  /* must be authenticated if this point was reached */
+  return 1;
+#else /* !USE_PAM */
   char *unencrypted, *encrypted, *correct;
 #if HAVE_GETSPNAM && HAVE_STRUCT_SPWD_SP_PWDP
   /* Shadow passwd stuff for SVR3 and maybe other systems.  */
@@ -243,6 +326,7 @@ correct_password (const struct passwd *p
   encrypted = crypt (unencrypted, correct);
   memset (unencrypted, 0, strlen (unencrypted));
   return STREQ (encrypted, correct);
+#endif /* !USE_PAM */
 }
 
 /* Update `environ' for the new shell based on PW, with SHELL being
@@ -256,12 +340,18 @@ modify_environment (const struct passwd 
       /* Leave TERM unchanged.  Set HOME, SHELL, USER, LOGNAME, PATH.
          Unset all other environment variables.  */
       char const *term = getenv ("TERM");
+      char const *display = getenv ("DISPLAY");
+      char const *xauthority = getenv ("XAUTHORITY");
       if (term)
         term = xstrdup (term);
       environ = xmalloc ((6 + !!term) * sizeof (char *));
       environ[0] = NULL;
       if (term)
         xsetenv ("TERM", term);
+      if (display)
+        xsetenv ("DISPLAY", display);
+      if (xauthority)
+        xsetenv ("XAUTHORITY", xauthority);
       xsetenv ("HOME", pw->pw_dir);
       xsetenv ("SHELL", shell);
       xsetenv ("USER", pw->pw_name);
@@ -294,8 +384,13 @@ change_identity (const struct passwd *pw
 {
 #ifdef HAVE_INITGROUPS
   errno = 0;
-  if (initgroups (pw->pw_name, pw->pw_gid) == -1)
+  if (initgroups (pw->pw_name, pw->pw_gid) == -1) {
+#ifdef USE_PAM
+    pam_close_session(pamh, 0);
+    pam_end(pamh, PAM_ABORT);
+#endif
     error (EXIT_FAILURE, errno, _("cannot set groups"));
+  }
   endgrent ();
 #endif
   if (setgid (pw->pw_gid))
@@ -304,6 +399,31 @@ change_identity (const struct passwd *pw
     error (EXIT_FAILURE, errno, _("cannot set user id"));
 }
 
+#ifdef USE_PAM
+static int caught=0;
+/* Signal handler for parent process later */
+static void su_catch_sig(int sig)
+{
+  ++caught;
+}
+
+int
+pam_copyenv (pam_handle_t *pamh)
+{
+  char **env;
+
+  env = pam_getenvlist(pamh);
+  if(env) {
+    while(*env) {
+	if (putenv (*env))
+	  xalloc_die ();
+	env++;
+    }
+  }
+  return(0);
+}
+#endif
+
 /* Run SHELL, or DEFAULT_SHELL if SHELL is empty.
    If COMMAND is nonzero, pass it to the shell with the -c option.
    Pass ADDITIONAL_ARGS to the shell as more arguments; there
@@ -311,17 +431,49 @@ change_identity (const struct passwd *pw
 
 static void
 run_shell (char const *shell, char const *command, char **additional_args,
-           size_t n_additional_args)
+           size_t n_additional_args, const struct passwd *pw)
 {
   size_t n_args = 1 + fast_startup + 2 * !!command + n_additional_args + 1;
   char const **args = xnmalloc (n_args, sizeof *args);
   size_t argno = 1;
+#ifdef USE_PAM
+  int child;
+  sigset_t ourset;
+  int status;
+
+  retval = pam_open_session(pamh,0);
+  if (retval != PAM_SUCCESS) {
+    fprintf (stderr, "could not open session\n");
+    exit (1);
+  }
+
+/* do this at the last possible moment, because environment variables may
+   be passed even in the session phase
+*/
+  if(pam_copyenv(pamh) != PAM_SUCCESS)
+     fprintf (stderr, "error copying PAM environment\n");
+  
+  /* Credentials should be set in the parent */ 
+  if (pam_setcred(pamh, PAM_ESTABLISH_CRED) != PAM_SUCCESS) {
+    pam_close_session(pamh, 0);
+    fprintf(stderr, "could not set PAM credentials\n");
+    exit(1);
+  }
+
+  child = fork();
+  if (child == 0) {  /* child shell */
+  change_identity (pw);
+  pam_end(pamh, 0);
+#endif
 
   if (simulate_login)
     {
       char *arg0;
       char *shell_basename;
 
+      if(chdir(pw->pw_dir))
+	      error(0, errno, _("warning: cannot change directory to %s"), pw->pw_dir);
+
       shell_basename = last_component (shell);
       arg0 = xmalloc (strlen (shell_basename) + 2);
       arg0[0] = '-';
@@ -346,6 +498,66 @@ run_shell (char const *shell, char const
     error (0, errno, "%s", shell);
     exit (exit_status);
   }
+#ifdef USE_PAM
+  } else if (child == -1) {
+      fprintf(stderr, "can not fork user shell: %s", strerror(errno));
+      pam_setcred(pamh, PAM_DELETE_CRED | PAM_SILENT);
+      pam_close_session(pamh, 0);
+      pam_end(pamh, PAM_ABORT);
+      exit(1);
+  }
+  /* parent only */
+  sigfillset(&ourset);
+  if (sigprocmask(SIG_BLOCK, &ourset, NULL)) {
+    fprintf(stderr, "%s: signal malfunction\n", PROGRAM_NAME);
+    caught = 1;
+  }
+  if (!caught) {
+    struct sigaction action;
+    action.sa_handler = su_catch_sig;
+    sigemptyset(&action.sa_mask);
+    action.sa_flags = 0;
+    sigemptyset(&ourset);
+    if (sigaddset(&ourset, SIGTERM)
+        || sigaddset(&ourset, SIGALRM)
+        || sigaction(SIGTERM, &action, NULL)
+        || sigprocmask(SIG_UNBLOCK, &ourset, NULL)) {
+      fprintf(stderr, "%s: signal masking malfunction\n", PROGRAM_NAME);
+      caught = 1;
+    }
+  }
+  if (!caught) {
+    do {
+      int pid;
+
+      pid = waitpid(-1, &status, WUNTRACED);
+
+      if (WIFSTOPPED(status)) {
+          kill(getpid(), SIGSTOP);
+          /* once we get here, we must have resumed */
+          kill(pid, SIGCONT);
+      }
+    } while (WIFSTOPPED(status));
+  }
+
+  if (caught) {
+    fprintf(stderr, "\nSession terminated, killing shell...");
+    kill (child, SIGTERM);
+  }
+  /* Not checking retval on this because we need to call close session */
+  pam_setcred(pamh, PAM_DELETE_CRED | PAM_SILENT);
+  retval = pam_close_session(pamh, 0);
+  PAM_BAIL_P_VOID;
+  retval = pam_end(pamh, PAM_SUCCESS);
+  PAM_BAIL_P_VOID;
+  if (caught) {
+    sleep(2);
+    kill(child, SIGKILL);
+    fprintf(stderr, " ...killed.\n");
+    exit(-1);
+  }
+  exit (WEXITSTATUS(status));
+#endif /* USE_PAM */
 }
 
 /* Return true if SHELL is a restricted shell (one not returned by
@@ -513,9 +725,9 @@ main (int argc, char **argv)
   shell = xstrdup (shell ? shell : pw->pw_shell);
   modify_environment (pw, shell);
 
+#ifndef USE_PAM
   change_identity (pw);
-  if (simulate_login && chdir (pw->pw_dir) != 0)
-    error (0, errno, _("warning: cannot change directory to %s"), pw->pw_dir);
+#endif
 
-  run_shell (shell, command, argv + optind, MAX (0, argc - optind));
+  run_shell (shell, command, argv + optind, MAX (0, argc - optind), pw);
 }