Prevent unintended file desriptor leak in grantpt.

The pt_chown program is completely transparently called.  It might
not be able to live with the various file descriptors the program
has open at the time of the call (e.g., under SELinux).  Close all
but the needed descriptor and connect stdin, stdout, and stderr
with /dev/null.  pt_chown shouldn't print anything when called to
do real work.

(cherry picked from commit 139ee08)

ChangeLog

@@ -1,5 +1,11 @@
 2009-11-24  Ulrich Drepper  <drepper@redhat.com>
 
+	* sysdeps/unix/grantpt.c (grantpt): Use CLOSE_ALL_FDS is available
+	before the exec.
+	* sysdeps/unix/sysv/linux/grantpt.c: New file.
+	* login/programs/pt_chown.c (main): Don't print message on errors
+	when doing real work.
+
 	* csu/elf-init.c (__libc_csu_irel): New function.  Code to perform
 	irel relocations split out from...
 	(__libc_csu_init): ...here.

login/programs/pt_chown.c

@@ -154,8 +154,7 @@ main (int argc, char *argv[])
 # define ncap_list (sizeof (cap_list) / sizeof (cap_list[0]))
 	  cap_t caps = cap_init ();
 	  if (caps == NULL)
-	    error (FAIL_ENOMEM, errno,
-		   _("Failed to initialize drop of capabilities"));
+	    return FAIL_ENOMEM;
 
 	  /* There is no reason why these should not work.  */
 	  cap_set_flag (caps, CAP_PERMITTED, ncap_list, cap_list, CAP_SET);
@@ -166,7 +165,7 @@ main (int argc, char *argv[])
 	  cap_free (caps);
 
 	  if (__builtin_expect (res != 0, 0))
-	    error (FAIL_EXEC, errno, _("cap_set_proc failed"));
+	    return FAIL_EXEC;
 	}
 #endif
 

sysdeps/unix/grantpt.c

@@ -190,6 +190,10 @@ grantpt (int fd)
 	if (__dup2 (fd, PTY_FILENO) < 0)
 	  _exit (FAIL_EBADF);
 
+#ifdef CLOSE_ALL_FDS
+      CLOSE_ALL_FDS ();
+#endif
+
       execle (_PATH_PT_CHOWN, basename (_PATH_PT_CHOWN), NULL, NULL);
       _exit (FAIL_EXEC);
     }

sysdeps/unix/sysv/linux/grantpt.c

@@ -0,0 +1,42 @@
+#include <assert.h>
+#include <ctype.h>
+#include <dirent.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <paths.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#include "not-cancel.h"
+#include "pty-private.h"
+
+
+/* Close all file descriptors except the one specified.  */
+static void
+close_all_fds (void)
+{
+  DIR *dir = opendir ("/proc/self/fd");
+  if (dir != NULL)
+    {
+      struct dirent64 *d;
+      while ((d = readdir64 (dir)) != NULL)
+	if (isdigit (d->d_name[0]))
+	  {
+	    char *endp;
+	    long int fd = strtol (d->d_name, &endp, 10);
+	    if (*endp == '\0' && fd != PTY_FILENO && fd != dirfd (dir))
+	      close_not_cancel_no_status (fd);
+	  }
+
+      closedir (dir);
+
+      int nullfd = open_not_cancel_2 (_PATH_DEVNULL, O_RDONLY);
+      assert (nullfd == STDIN_FILENO);
+      nullfd = open_not_cancel_2 (_PATH_DEVNULL, O_WRONLY);
+      assert (nullfd == STDOUT_FILENO);
+      __dup2 (STDOUT_FILENO, STDERR_FILENO);
+    }
+}
+#define CLOSE_ALL_FDS() close_all_fds()
+
+#include <sysdeps/unix/grantpt.c>