qemu: Add a subtest nx.

Test whether nx(cpu) bit takes effect in guest.
Signed-off-by: NKen Cao <kcao@redhat.com>
Signed-off-by: NFeng Yang <fyang@redhat.com>
KVM test: Rename the nx_exploit.py to nx.py
Signed-off-by: NJason Wang <jasowang@redhat.com>
Reviewed-by: NYolkfull Chow <yzhou@redhat.com>

qemu/tests/nx.py

+import os, logging
+from autotest.client.shared import error
+
+
+@error.context_aware
+def run_nx(test, params, env):
+    """
+    try to exploit the guest to test whether nx(cpu) bit takes effect.
+
+    1) boot the guest
+    2) cp the exploit prog into the guest
+    3) run the exploit
+
+    @param test: QEMU test object
+    @param params: Dictionary with the test parameters
+    @param env: Dictionary with test environment.
+    """
+
+
+    vm = env.get_vm(params["main_vm"])
+    vm.verify_alive()
+    session = vm.wait_for_login(timeout=int(params.get("login_timeout", 360)))
+
+    exploit_file = os.path.join(test.virtdir, 'deps/x64_sc_rdo.c')
+    dst_dir = '/tmp'
+
+    error.context("Copy the Exploit file to guest.", logging.info)
+    vm.copy_files_to(exploit_file, dst_dir)
+
+    error.context("Build exploit program in guest.", logging.info)
+    build_exploit = "gcc -o /tmp/nx_exploit /tmp/x64_sc_rdo.c"
+    if session.cmd_status(build_exploit):
+        raise error.TestError("Failed to build the exploit program")
+
+    error.context("Run exploit program in guest.", logging.info)
+    exec_exploit = "/tmp/nx_exploit"
+    # if nx is enabled (by default), the program failed.
+    # segmentation error. return value of shell is not zero.
+    exec_res = session.cmd_status(exec_exploit)
+    nx_on = params.get('nx_on', 'yes')
+    if nx_on == 'yes':
+        if exec_res:
+            logging.info('NX works good.')
+            error.context("Using execstack to remove the protection.",
+                          logging.info)
+            enable_exec = 'execstack -s /tmp/nx_exploit'
+            if session.cmd_status(enable_exec):
+                if session.cmd_status("execstack --help"):
+                    msg = "Please make sure guest have execstack command."
+                    raise error.TestError(msg)
+                raise error.TestError('Failed to enable the execstack')
+
+            if session.cmd_status(exec_exploit):
+                raise error.TestFail('NX is still protecting. Error.')
+            else:
+                logging.info('NX is disabled as desired. good')
+        else:
+            raise error.TestFail('Fatal Error: NX does not protect anything!')
+    else:
+        if exec_res:
+            msg = "qemu fail to disable 'nx' flag or the exploit is corrupted."
+            raise error.TestError(msg)
+        else:
+            logging.info('NX is disabled, and this Test Case passed.')
+    if session:
+        session.close()