[Kimchi-devel] [PATCH] add a method to probe the permission as qemu user

[shaohef at linux.vnet.ibm.com]

From: ShaoHe Feng <shaohef at linux.vnet.ibm.com>

now I want to improve the template integrity verification.
I need to check the 'qemu' user can open an iso files.

This patch is used to 'qemu' user has permission to open a file.

Test this patch:
$ mkdir -p a/b/c
$ touch a/b/c/f
$ chmod o-x a/b/c
$ sudo PYTHONPATH=src python -c '
from kimchi.utils import probe_file_permission_as_user
print probe_file_permission_as_user("a/b/c/f", "qemu")'

It will return False
change another user, it may return True

Signed-off-by: ShaoHe Feng <shaohef at linux.vnet.ibm.com>
---
 src/kimchi/utils.py | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/src/kimchi/utils.py b/src/kimchi/utils.py
index d4ab1a1..baee936 100644
--- a/src/kimchi/utils.py
+++ b/src/kimchi/utils.py
@@ -22,8 +22,11 @@
 #
 
 import cherrypy
+import grp
+from multiprocessing import Process, Queue
 import os
 import psutil
+import pwd
 import re
 import subprocess
 import urllib2
@@ -234,3 +237,24 @@ def run_setfacl_set_attr(path, attr="r", user=""):
     set_user = ["setfacl", "--modify", "user:%s:%s" % (user, attr), path]
     out, error, ret = run_command(set_user)
     return ret == 0
+
+
+def probe_file_permission_as_user(file, user):
+    def probe_permission(q, file, user):
+        uid = pwd.getpwnam(user).pw_uid
+        gid = pwd.getpwnam(user).pw_gid
+        gids = [g.gr_gid for g in grp.getgrall() if user in g.gr_mem]
+        os.setgid(gid)
+        os.setgroups(gids)
+        os.setuid(uid)
+        try:
+            with open(file) as f:
+                q.put(True)
+        except Exception as e:
+            q.put(False)
+
+    queue = Queue()
+    p = Process(target=probe_permission, args=(queue, file, user))
+    p.start()
+    p.join()
+    return queue.get()
-- 
1.8.4.2