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From ee3d4021aaaeacff7cf2addcdaa48859fffba2aa Mon Sep 17 00:00:00 2001
From: Andreas Schwab <schwab@redhat.com>
Date: Thu, 3 Feb 2011 15:45:02 +0100
Subject: [PATCH] Replace setuid by file capabilities

* login/programs/pt_chown.c (main): Check for valid file
descriptor instead of privileges.  Be careful to drop all
capabilities when not needed.

---
 ChangeLog                 |    6 ++++++
 login/programs/pt_chown.c |   14 +++++++++-----
 3 files changed, 16 insertions(+), 6 deletions(-)

--- a/login/programs/pt_chown.c
+++ b/login/programs/pt_chown.c
@@ -28,6 +28,7 @@
 #include <string.h>
 #include <sys/stat.h>
 #include <unistd.h>
+#include <fcntl.h>
 #ifdef HAVE_LIBCAP
 # include <sys/capability.h>
 # include <sys/prctl.h>
@@ -142,7 +143,7 @@ main (int argc, char *argv[])
   uid_t uid = getuid ();
   int remaining;
 
-  if (argc == 1 && euid == 0)
+  if (argc == 1 && fcntl (PTY_FILENO, F_GETFD) == 0)
     {
 #ifdef HAVE_LIBCAP
   /* Drop privileges.  */
@@ -175,6 +176,13 @@ main (int argc, char *argv[])
 
   /* We aren't going to be using privileges, so drop them right now. */
   setuid (uid);
+#ifdef HAVE_LIBCAP
+  cap_t caps = cap_init ();
+  if (caps == NULL)
+    error (1, errno, "cap_init");
+  cap_set_proc (caps);
+  cap_free (caps);
+#endif
 
   /* Set locale via LC_ALL.  */
   setlocale (LC_ALL, "");
@@ -194,9 +202,5 @@ main (int argc, char *argv[])
       return EXIT_FAILURE;
     }
 
-  /* Check if we are properly installed.  */
-  if (euid != 0)
-    error (FAIL_EXEC, 0, gettext ("needs to be installed setuid `root'"));
-
   return EXIT_SUCCESS;
 }