gdb-attach-fail-reasons-5of5.patch

;; Print reasons for failed attach/spawn incl. SELinux deny_ptrace (BZ 786878).
;;=push+jan

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

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.

Author: ivanivanov884

gdb/config.in

@@ -261,6 +261,9 @@
 /* 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
 
@@ -384,6 +387,9 @@
 /* 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
 

gdb/configure

@@ -15790,6 +15790,64 @@ cat >>confdefs.h <<_ACEOF
 _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.

gdb/configure.ac

@@ -2020,6 +2020,10 @@ case $host_os in
 esac
 AC_DEFINE_UNQUOTED(GDBINIT,"$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,

gdb/gdbserver/config.in

@@ -126,6 +126,9 @@
 /* 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
 
@@ -202,6 +205,9 @@
 /* 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
 

gdb/gdbserver/configure

@@ -8589,6 +8589,64 @@ if $want_ipa ; then
    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
+
+
 
 
 

gdb/gdbserver/configure.ac

@@ -478,6 +478,10 @@ if $want_ipa ; then
    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)

gdb/gdbserver/linux-low.c

@@ -971,7 +971,16 @@ linux_ptrace_fun ()
 {
   if (ptrace (PTRACE_TRACEME, 0, (PTRACE_TYPE_ARG3) 0,
 	      (PTRACE_TYPE_ARG4) 0) < 0)
-    trace_start_error_with_name ("ptrace");
+    {
+      int save_errno = errno;
+
+      std::string msg (linux_ptrace_create_warnings ());
+
+      msg += _("Cannot trace created process");
+
+      errno = save_errno;
+      trace_start_error_with_name (msg.c_str ());
+    }
 
   if (setpgid (0, 0) < 0)
     trace_start_error_with_name ("setpgid");

gdb/linux-nat.c

@@ -1098,7 +1098,16 @@ linux_nat_target::create_inferior (const char *exec_file,
   /* Make sure we report all signals during startup.  */
   pass_signals ({});
 
-  inf_ptrace_target::create_inferior (exec_file, allargs, env, from_tty);
+  try
+    {
+      inf_ptrace_target::create_inferior (exec_file, allargs, env, from_tty);
+    }
+  catch (const gdb_exception_error &ex)
+    {
+      std::string result =  linux_ptrace_create_warnings ();
+
+      throw_error (ex.error, "%s%s", result.c_str (), ex.what ());
+    }
 }
 
 /* Callback for linux_proc_attach_tgid_threads.  Attach to PTID if not

gdb/nat/linux-ptrace.c

@@ -25,6 +25,10 @@
 #include <sys/procfs.h>
 #endif
 
+#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.  */
@@ -50,6 +54,8 @@ linux_ptrace_attach_fail_reason (pid_t pid)
 		      "terminated"),
 		    (int) pid);
 
+  result += linux_ptrace_create_warnings ();
+
   return result;
 }
 
@@ -586,6 +592,25 @@ linux_ptrace_init_warnings (void)
   linux_ptrace_test_ret_to_nx ();
 }
 
+/* Print all possible reasons we could fail to create a traced process.  */
+
+std::string
+linux_ptrace_create_warnings ()
+{
+  std::string result;
+
+#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)
+    string_appendf (result,
+		    _("the SELinux boolean 'deny_ptrace' is enabled, "
+		      "you can disable this process attach protection by: "
+		      "(gdb) shell sudo setsebool deny_ptrace=0\n"));
+#endif /* HAVE_LIBSELINUX */
+  return result;
+}
+
 /* Extract extended ptrace event from wait status.  */
 
 int

gdb/nat/linux-ptrace.h

@@ -184,6 +184,7 @@ extern std::string linux_ptrace_attach_fail_reason (pid_t pid);
 extern std::string linux_ptrace_attach_fail_reason_string (ptid_t ptid, int err);
 
 extern void linux_ptrace_init_warnings (void);
+extern std::string linux_ptrace_create_warnings ();
 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);