[Kimchi-devel] [PATCH V8] add a method to fix search permissions

[shaohef at linux.vnet.ibm.com]

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

If the user of path is the same user of "qemu-kvm", then set the fix
the permission directly.

Or just use setfacl to set the path search permission just for "qemu-kvm"
user.

We do not fix the permission for others.

Usage:
check_path_permission("/tmp/need/to/fix/path", username)
fix_path_permission("/tmp/need/to/fix/path", username)

test:
$ mkdir -p a/b/c
$ echo "test" > a/b/c/f
$ sudo chmod a-xr -R a/b/c/f

$ sudo PYTHONPATH=./src python -c '
from kimchi.utils import *
path = "a/b/c/f"
print check_path_permission(path, "qemu")
'

$ sudo PYTHONPATH=./src python -c '
from kimchi.utils import *
path = "a/b/c/f"
print fix_path_permission(path, "qemu")
'

$ cat a/b/c/f

Signed-off-by: ShaoHe Feng <shaohef at linux.vnet.ibm.com>
Signed-off-by: Aline Manera <alinefm at linux.vnet.ibm.com>
Signed-off-by: Royce Lv <lvroyce at linux.vnet.ibm.com>
---
 src/kimchi/utils.py | 149 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 149 insertions(+)

diff --git a/src/kimchi/utils.py b/src/kimchi/utils.py
index 0e66214..39a6cf6 100644
--- a/src/kimchi/utils.py
+++ b/src/kimchi/utils.py
@@ -22,7 +22,11 @@
 #
 
 import cherrypy
+import grp
 import os
+import pwd
+import re
+import stat
 import subprocess
 import urllib2
 
@@ -179,3 +183,148 @@ def patch_find_nfs_target(nfs_server):
         target['type'] = 'nfs'
         target['host_name'] = nfs_server
     return targets
+
+
+def name_uid(user):
+    return pwd.getpwnam(user).pw_uid
+
+
+def get_group_ids(user):
+    gids = [g.gr_gid for g in grp.getgrall() if user in g.gr_mem]
+    gid = pwd.getpwnam(user).pw_gid
+    gids.append(grp.getgrgid(gid).gr_gid)
+    return gids
+
+
+def get_groups(user):
+    gids = get_group_ids(user)
+    return [grp.getgrgid(gid).gr_name for gid in gids]
+
+
+def run_setfacl_set_attr(path, attr="x", user="qemu"):
+    set_user = ["setfacl", "--modify", "user:%s:%s" % (user, attr), path]
+    out, error, ret = run_command(set_user)
+    return ret == 0
+
+
+def run_getfacl(path, attr="x", user="qemu", groups=[]):
+    attr = "".join(map(lambda x, y: x if y else ".", ["r", "w", "x"],
+                       [b in attr for b in ["r", "w", "x"]]))
+    cmd = ["getfacl", path]
+    out, error, ret = run_command(cmd)
+    if out and ret == 0:
+        res = re.findall("user:%s:%s" % (user, attr), out)
+        if res:
+            return True
+        res = re.findall("(?<=group:)(.*)(?=:%s)" % attr,
+                         out) if groups else []
+        return list(set(res) & set(groups)) != []
+    return False
+
+
+def set_x_on_path(path, who="other"):
+    S_IXWHO = ((stat.S_IXUSR if who == "user" else None) or
+               (stat.S_IXGRP if who == "group" else None) or
+               (stat.S_IXOTH if who == "other" else None))
+
+    if S_IXWHO is None:
+        return False
+    mode = os.stat(path).st_mode | S_IXWHO
+    os.chmod(path, mode)
+    ret = os.stat(path).st_mode == mode
+    if not ret:
+        kimchi_log.debug("faild to set +x attribute on %s", path)
+    return ret
+
+
+def set_r_on_path(path, who="other"):
+    S_IXWHO = ((stat.S_IRUSR if who == "user" else None) or
+               (stat.S_IRGRP if who == "group" else None) or
+               (stat.S_IROTH if who == "other" else None))
+
+    if S_IXWHO is None:
+        return False
+    mode = os.stat(path).st_mode | S_IXWHO
+    os.chmod(path, mode)
+    ret = os.stat(path).st_mode == mode
+    if not ret:
+        kimchi_log.debug("faild to set +x attribute on %s", path)
+    return ret
+
+
+def get_x_on_path(path, uid, gids=[]):
+    try:
+        st = os.stat(path)
+        mode = st.st_mode
+        return ((uid == st.st_uid and mode & stat.S_IXUSR == stat.S_IXUSR) or
+                (st.st_gid in gids and mode & stat.S_IXGRP == stat.S_IXGRP) or
+                mode & stat.S_IXOTH == stat.S_IXOTH)
+    except OSError as e:
+        kimchi_log.error("faild to get x attribute on %s as user id: %s. %s",
+                         path, uid, e.message)
+        return False
+
+
+def get_r_on_path(path, uid, gids=[]):
+    try:
+        st = os.stat(path)
+        mode = st.st_mode
+        return ((uid == st.st_uid and mode & stat.S_IRUSR == stat.S_IRUSR) or
+                (st.st_gid in gids and mode & stat.S_IRGRP == stat.S_IRGRP) or
+                mode & stat.S_IROTH == stat.S_IROTH)
+    except OSError as e:
+        kimchi_log.error("faild to get r attribute on %s as user id: %s. %s",
+                         path, uid, e.message)
+        return False
+
+
+def check_path_permission(path, user='qemu', groups=[]):
+    f = path if os.path.isfile(path) else None
+    groups = groups if groups else get_groups(user)
+    gids = [grp.getgrnam(group).gr_gid for group in groups] if groups else []
+    uid = name_uid(user)
+    path = os.path.abspath(path)
+    path = os.path.dirname(path) if f else path
+    paths = path.split("/")
+    paths = paths[1:]
+    path = "/"
+    for p in paths:
+        path = os.path.join(path, p)
+        if not (get_x_on_path(path, uid, gids) or
+                run_getfacl(path, 'x', user, groups)):
+            return False
+
+    return (f is not None and
+            (get_r_on_path(f, uid, gids) or
+             run_getfacl(f, 'r', user, groups)) or
+            False)
+
+
+def fix_path_permission(path, user='qemu', groups=[]):
+    f = path if os.path.isfile(path) else None
+    groups = groups if groups else get_groups(user)
+    gids = [grp.getgrnam(group).gr_gid for group in groups] if groups else []
+    uid = name_uid(user)
+    path = os.path.abspath(path)
+    path = os.path.dirname(path) if f else path
+    paths = path.split("/")
+    paths = paths[1:]
+    path = "/"
+    for p in paths:
+        path = os.path.join(path, p)
+        st = os.stat(path)
+        who = 'user' if st.st_uid == uid else None
+        if not (get_x_on_path(path, uid, gids) or
+                run_getfacl(path, 'x', user, groups) or
+                set_x_on_path(path, who) or
+                run_setfacl_set_attr(path, 'x', user)):
+            return False
+
+    st = os.stat(f)
+    who = 'user' if st.st_uid == uid else None
+    return (f is not None and
+            (get_r_on_path(f, uid, gids) or
+             run_getfacl(f, 'r', user, groups) or
+             set_r_on_path(f, who) or
+             run_setfacl_set_attr(f, 'r', user)) or
+            False)
-- 
1.8.4.2