http://sourceware.org/ml/gdb-patches/2012-03/msg00171.html

Subject: [patch 3/3] attach-fail-reasons: SELinux deny_ptrace

Hi,

and here is the last bit for new SELinux 'deny_ptrace':

	https://bugzilla.redhat.com/show_bug.cgi?id=786878

As even PTRACE_TRACEME fails in such case it needs to install hook for even

that event.

Thanks,

Jan

gdb/

2012-03-06  Jan Kratochvil  <jan.kratochvil@redhat.com>

	* common/linux-ptrace.c [HAVE_SELINUX_SELINUX_H]: include

	selinux/selinux.h.

	(linux_ptrace_attach_warnings): Call linux_ptrace_create_warnings.

	(linux_ptrace_create_warnings): New.

	* common/linux-ptrace.h (linux_ptrace_create_warnings): New declaration.

	* config.in: Regenerate.

	* configure: Regenerate.

	* configure.ac: Check selinux/selinux.h and the selinux library.

	* inf-ptrace.c (inf_ptrace_me): Check the ptrace result.

	* linux-nat.c (linux_nat_create_inferior): New variable ex.  Wrap

	to_create_inferior into TRY_CATCH, call linux_ptrace_create_warnings.

gdb/gdbserver/

	* config.in: Regenerate.

	* configure: Regenerate.

	* configure.ac: Check selinux/selinux.h and the selinux library.

	* linux-low.c (linux_traceme): New function.

	(linux_create_inferior, linux_tracefork_child): Call it instead of

	direct ptrace.

Index: gdb-7.11.90.20160829/gdb/nat/linux-ptrace.c

===================================================================

--- gdb-7.11.90.20160829.orig/gdb/nat/linux-ptrace.c	2016-08-29 09:35:26.798230659 +0200

+++ gdb-7.11.90.20160829/gdb/nat/linux-ptrace.c	2016-08-29 09:35:43.162384100 +0200

@@ -25,6 +25,10 @@

 #include "gdb_ptrace.h"

 #include <sys/procfs.h>

+#ifdef HAVE_SELINUX_SELINUX_H

+# include <selinux/selinux.h>

+#endif /* HAVE_SELINUX_SELINUX_H */

+

 /* Stores the ptrace options supported by the running kernel.

    A value of -1 means we did not check for features yet.  A value

    of 0 means there are no supported features.  */

@@ -49,6 +53,8 @@

     buffer_xml_printf (buffer, _("process %d is a zombie "

 				 "- the process has already terminated"),

 		       (int) pid);

+

+  linux_ptrace_create_warnings (buffer);

 }

 /* See linux-ptrace.h.  */

@@ -592,6 +598,22 @@

   linux_ptrace_test_ret_to_nx ();

 }

+/* Print all possible reasons we could fail to create a traced process.  */

+

+void

+linux_ptrace_create_warnings (struct buffer *buffer)

+{

+#ifdef HAVE_LIBSELINUX

+  /* -1 is returned for errors, 0 if it has no effect, 1 if PTRACE_ATTACH is

+     forbidden.  */

+  if (security_get_boolean_active ("deny_ptrace") == 1)

+    buffer_xml_printf (buffer,

+		       _("the SELinux boolean 'deny_ptrace' is enabled, "

+			 "you can disable this process attach protection by: "

+			 "(gdb) shell sudo setsebool deny_ptrace=0"));

+#endif /* HAVE_LIBSELINUX */

+}

+

 /* Extract extended ptrace event from wait status.  */

 int

Index: gdb-7.11.90.20160829/gdb/nat/linux-ptrace.h

===================================================================

--- gdb-7.11.90.20160829.orig/gdb/nat/linux-ptrace.h	2016-08-29 09:35:26.798230659 +0200

+++ gdb-7.11.90.20160829/gdb/nat/linux-ptrace.h	2016-08-29 09:35:43.162384100 +0200

@@ -185,6 +185,7 @@

 extern char *linux_ptrace_attach_fail_reason_string (ptid_t ptid, int err);

 extern void linux_ptrace_init_warnings (void);

+extern void linux_ptrace_create_warnings (struct buffer *buffer);

 extern void linux_check_ptrace_features (void);

 extern void linux_enable_event_reporting (pid_t pid, int attached);

 extern void linux_disable_event_reporting (pid_t pid);

Index: gdb-7.11.90.20160829/gdb/configure.ac

===================================================================

--- gdb-7.11.90.20160829.orig/gdb/configure.ac	2016-08-29 09:35:26.799230668 +0200

+++ gdb-7.11.90.20160829/gdb/configure.ac	2016-08-29 09:35:43.163384109 +0200

@@ -2108,6 +2108,10 @@

 esac

 AC_DEFINE_UNQUOTED(GDBINIT,"$gdbinit",[The .gdbinit filename.])

+dnl Check security_get_boolean_active availability.

+AC_CHECK_HEADERS(selinux/selinux.h)

+AC_CHECK_LIB(selinux, security_get_boolean_active)

+

 dnl Handle optional features that can be enabled.

 # Support for --with-sysroot is a copy of GDB_AC_WITH_DIR,

Index: gdb-7.11.90.20160829/gdb/gdbserver/configure.ac

===================================================================

--- gdb-7.11.90.20160829.orig/gdb/gdbserver/configure.ac	2016-08-29 09:35:26.799230668 +0200

+++ gdb-7.11.90.20160829/gdb/gdbserver/configure.ac	2016-08-29 09:35:43.163384109 +0200

@@ -472,6 +472,10 @@

    fi

 fi

+dnl Check security_get_boolean_active availability.

+AC_CHECK_HEADERS(selinux/selinux.h)

+AC_CHECK_LIB(selinux, security_get_boolean_active)

+

 AC_SUBST(GDBSERVER_DEPFILES)

 AC_SUBST(GDBSERVER_LIBS)

 AC_SUBST(srv_xmlbuiltin)

Index: gdb-7.11.90.20160829/gdb/gdbserver/linux-low.c

===================================================================

--- gdb-7.11.90.20160829.orig/gdb/gdbserver/linux-low.c	2016-08-29 09:35:26.801230687 +0200

+++ gdb-7.11.90.20160829/gdb/gdbserver/linux-low.c	2016-08-29 09:35:43.165384128 +0200

@@ -933,6 +933,29 @@

   return lwp;

 }

+/* Execute PTRACE_TRACEME with error checking.  */

+

+static void

+linux_traceme (const char *program)

+{

+  int save_errno;

+  struct buffer buffer;

+

+  errno = 0;

+  if (ptrace (PTRACE_TRACEME, 0,

+	      (PTRACE_TYPE_ARG3) 0, (PTRACE_TYPE_ARG4) 0) == 0)

+    return;

+

+  save_errno = errno;

+  buffer_init (&buffer);

+  linux_ptrace_create_warnings (&buffer);

+  buffer_grow_str0 (&buffer, "");

+  fprintf (stderr, _("%sCannot trace created process %s: %s.\n"),

+	   buffer_finish (&buffer), program, strerror (save_errno));

+  fflush (stderr);

+  _exit (0177);

+}

+

 /* Start an inferior process and returns its pid.

    ALLARGS is a vector of program-name and args. */

@@ -956,7 +979,7 @@

   if (pid == 0)

     {

       close_most_fds ();

-      ptrace (PTRACE_TRACEME, 0, (PTRACE_TYPE_ARG3) 0, (PTRACE_TYPE_ARG4) 0);

+      linux_traceme (program);

       setpgid (0, 0);

Index: gdb-7.11.90.20160829/gdb/inf-ptrace.c

===================================================================

--- gdb-7.11.90.20160829.orig/gdb/inf-ptrace.c	2016-08-29 09:35:26.801230687 +0200

+++ gdb-7.11.90.20160829/gdb/inf-ptrace.c	2016-08-29 09:35:43.165384128 +0200

@@ -79,7 +79,15 @@

 inf_ptrace_me (void)

 {

   /* "Trace me, Dr. Memory!"  */

+  errno = 0;

   ptrace (PT_TRACE_ME, 0, (PTRACE_TYPE_ARG3)0, 0);

+  if (errno != 0)

+    {

+      fprintf_unfiltered (gdb_stderr, _("Cannot create process: %s\n"),

+			  safe_strerror (errno));

+      gdb_flush (gdb_stderr);

+      _exit (0177);

+    }

 }

 /* Start a new inferior Unix child process.  EXEC_FILE is the file to

Index: gdb-7.11.90.20160829/gdb/linux-nat.c

===================================================================

--- gdb-7.11.90.20160829.orig/gdb/linux-nat.c	2016-08-29 09:35:26.802230697 +0200

+++ gdb-7.11.90.20160829/gdb/linux-nat.c	2016-08-29 09:35:43.166384137 +0200

@@ -1102,6 +1102,7 @@

 {

   struct cleanup *restore_personality

     = maybe_disable_address_space_randomization (disable_randomization);

+  volatile struct gdb_exception ex;

   /* The fork_child mechanism is synchronous and calls target_wait, so

      we have to mask the async mode.  */

@@ -1109,7 +1110,28 @@

   /* Make sure we report all signals during startup.  */

   linux_nat_pass_signals (ops, 0, NULL);

-  linux_ops->to_create_inferior (ops, exec_file, allargs, env, from_tty);

+  TRY

+    {

+      linux_ops->to_create_inferior (ops, exec_file, allargs, env, from_tty);

+    }

+  CATCH (ex, RETURN_MASK_ERROR)

+    {

+      struct buffer buffer;

+      char *message, *buffer_s;

+

+      message = xstrdup (ex.message);

+      make_cleanup (xfree, message);

+

+      buffer_init (&buffer);

+      linux_ptrace_create_warnings (&buffer);

+

+      buffer_grow_str0 (&buffer, "");

+      buffer_s = buffer_finish (&buffer);

+      make_cleanup (xfree, buffer_s);

+

+      throw_error (ex.error, "%s%s", buffer_s, message);

+    }

+  END_CATCH

   do_cleanups (restore_personality);

 }

Index: gdb-7.11.90.20160829/gdb/config.in

===================================================================

--- gdb-7.11.90.20160829.orig/gdb/config.in	2016-08-29 09:35:26.803230706 +0200

+++ gdb-7.11.90.20160829/gdb/config.in	2016-08-29 09:35:43.166384137 +0200

@@ -267,6 +267,9 @@

 /* Define if librpm library is being used. */

 #undef HAVE_LIBRPM

+/* Define to 1 if you have the `selinux' library (-lselinux). */

+#undef HAVE_LIBSELINUX

+

 /* Define to 1 if you have the <libunwind-ia64.h> header file. */

 #undef HAVE_LIBUNWIND_IA64_H

@@ -399,6 +402,9 @@

 /* Define to 1 if you have the `scm_new_smob' function. */

 #undef HAVE_SCM_NEW_SMOB

+/* Define to 1 if you have the <selinux/selinux.h> header file. */

+#undef HAVE_SELINUX_SELINUX_H

+

 /* Define to 1 if you have the `setlocale' function. */

 #undef HAVE_SETLOCALE

Index: gdb-7.11.90.20160829/gdb/configure

===================================================================

--- gdb-7.11.90.20160829.orig/gdb/configure	2016-08-29 09:35:26.806230734 +0200

+++ gdb-7.11.90.20160829/gdb/configure	2016-08-29 09:35:43.170384175 +0200

@@ -14642,6 +14642,64 @@

 _ACEOF

+for ac_header in selinux/selinux.h

+do :

+  ac_fn_c_check_header_mongrel "$LINENO" "selinux/selinux.h" "ac_cv_header_selinux_selinux_h" "$ac_includes_default"

+if test "x$ac_cv_header_selinux_selinux_h" = x""yes; then :

+  cat >>confdefs.h <<_ACEOF

+#define HAVE_SELINUX_SELINUX_H 1

+_ACEOF

+

+fi

+

+done

+

+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for security_get_boolean_active in -lselinux" >&5

+$as_echo_n "checking for security_get_boolean_active in -lselinux... " >&6; }

+if test "${ac_cv_lib_selinux_security_get_boolean_active+set}" = set; then :

+  $as_echo_n "(cached) " >&6

+else

+  ac_check_lib_save_LIBS=$LIBS

+LIBS="-lselinux  $LIBS"

+cat confdefs.h - <<_ACEOF >conftest.$ac_ext

+/* end confdefs.h.  */

+

+/* Override any GCC internal prototype to avoid an error.

+   Use char because int might match the return type of a GCC

+   builtin and then its argument prototype would still apply.  */

+#ifdef __cplusplus

+extern "C"

+#endif

+char security_get_boolean_active ();

+int

+main ()

+{

+return security_get_boolean_active ();

+  ;

+  return 0;

+}

+_ACEOF

+if ac_fn_c_try_link "$LINENO"; then :

+  ac_cv_lib_selinux_security_get_boolean_active=yes

+else

+  ac_cv_lib_selinux_security_get_boolean_active=no

+fi

+rm -f core conftest.err conftest.$ac_objext \

+    conftest$ac_exeext conftest.$ac_ext

+LIBS=$ac_check_lib_save_LIBS

+fi

+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lib_selinux_security_get_boolean_active" >&5

+$as_echo "$ac_cv_lib_selinux_security_get_boolean_active" >&6; }

+if test "x$ac_cv_lib_selinux_security_get_boolean_active" = x""yes; then :

+  cat >>confdefs.h <<_ACEOF

+#define HAVE_LIBSELINUX 1

+_ACEOF

+

+  LIBS="-lselinux $LIBS"

+

+fi

+

+

 # Support for --with-sysroot is a copy of GDB_AC_WITH_DIR,

 # except that the argument to --with-sysroot is optional.

Index: gdb-7.11.90.20160829/gdb/gdbserver/config.in

===================================================================

--- gdb-7.11.90.20160829.orig/gdb/gdbserver/config.in	2016-08-29 09:35:26.807230743 +0200

+++ gdb-7.11.90.20160829/gdb/gdbserver/config.in	2016-08-29 09:35:43.170384175 +0200

@@ -120,6 +120,9 @@

 /* Define to 1 if you have the `mcheck' library (-lmcheck). */

 #undef HAVE_LIBMCHECK

+/* Define to 1 if you have the `selinux' library (-lselinux). */

+#undef HAVE_LIBSELINUX

+

 /* Define if the target supports branch tracing. */

 #undef HAVE_LINUX_BTRACE

@@ -196,6 +199,9 @@

 /* Define to 1 if you have the `pwrite' function. */

 #undef HAVE_PWRITE

+/* Define to 1 if you have the <selinux/selinux.h> header file. */

+#undef HAVE_SELINUX_SELINUX_H

+

 /* Define to 1 if you have the `setns' function. */

 #undef HAVE_SETNS

Index: gdb-7.11.90.20160829/gdb/gdbserver/configure

===================================================================

--- gdb-7.11.90.20160829.orig/gdb/gdbserver/configure	2016-08-29 09:35:26.809230762 +0200

+++ gdb-7.11.90.20160829/gdb/gdbserver/configure	2016-08-29 09:35:43.172384194 +0200

@@ -7561,6 +7561,64 @@

    fi

 fi

+for ac_header in selinux/selinux.h

+do :

+  ac_fn_c_check_header_mongrel "$LINENO" "selinux/selinux.h" "ac_cv_header_selinux_selinux_h" "$ac_includes_default"

+if test "x$ac_cv_header_selinux_selinux_h" = x""yes; then :

+  cat >>confdefs.h <<_ACEOF

+#define HAVE_SELINUX_SELINUX_H 1

+_ACEOF

+

+fi

+

+done

+

+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for security_get_boolean_active in -lselinux" >&5

+$as_echo_n "checking for security_get_boolean_active in -lselinux... " >&6; }

+if test "${ac_cv_lib_selinux_security_get_boolean_active+set}" = set; then :

+  $as_echo_n "(cached) " >&6

+else

+  ac_check_lib_save_LIBS=$LIBS

+LIBS="-lselinux  $LIBS"

+cat confdefs.h - <<_ACEOF >conftest.$ac_ext

+/* end confdefs.h.  */

+

+/* Override any GCC internal prototype to avoid an error.

+   Use char because int might match the return type of a GCC

+   builtin and then its argument prototype would still apply.  */

+#ifdef __cplusplus

+extern "C"

+#endif

+char security_get_boolean_active ();

+int

+main ()

+{

+return security_get_boolean_active ();

+  ;

+  return 0;

+}

+_ACEOF

+if ac_fn_c_try_link "$LINENO"; then :

+  ac_cv_lib_selinux_security_get_boolean_active=yes

+else

+  ac_cv_lib_selinux_security_get_boolean_active=no

+fi

+rm -f core conftest.err conftest.$ac_objext \

+    conftest$ac_exeext conftest.$ac_ext

+LIBS=$ac_check_lib_save_LIBS

+fi

+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lib_selinux_security_get_boolean_active" >&5

+$as_echo "$ac_cv_lib_selinux_security_get_boolean_active" >&6; }

+if test "x$ac_cv_lib_selinux_security_get_boolean_active" = x""yes; then :

+  cat >>confdefs.h <<_ACEOF

+#define HAVE_LIBSELINUX 1

+_ACEOF

+

+  LIBS="-lselinux $LIBS"

+

+fi

+

+