[Kimchi-devel] [PATCH V3 3/3] add a method to fix search permissions

Aline Manera alinefm at linux.vnet.ibm.com
Thu Dec 26 17:41:50 UTC 2013


On 12/24/2013 05:46 AM, shaohef at linux.vnet.ibm.com wrote:
> From: ShaoHe Feng <shaohef at linux.vnet.ibm.com>
>
> First will use setfacl to set the path search permission for user or
> group, if failed then set search permission for others on the path.
>
> Usage:
> check_path_permission("/tmp/need/to/fix/path", username)
> fix_path_permission("/tmp/need/to/fix/path", username)
>
> Signed-off-by: ShaoHe Feng <shaohef at linux.vnet.ibm.com>
> Signed-off-by: Royce Lv <lvroyce at linux.vnet.ibm.com>
> ---
>   src/kimchi/utils.py | 116 +++++++++++++++++++++++++++++++++++++++++++++++++++-
>   1 file changed, 115 insertions(+), 1 deletion(-)
>
> diff --git a/src/kimchi/utils.py b/src/kimchi/utils.py
> index bf2a760..e94aeb1 100644
> --- a/src/kimchi/utils.py
> +++ b/src/kimchi/utils.py
> @@ -18,11 +18,15 @@
>   #
>   # You should have received a copy of the GNU Lesser General Public
>   # License along with this library; if not, write to the Free Software
> -# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
> +# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
>   #
>
>   import cherrypy
>   import os
> +import pwd
> +import re
> +import stat
> +import subprocess
>
>
>   from cherrypy.lib.reprconf import Parser
> @@ -33,6 +37,7 @@ from kimchi import config
>
>   kimchi_log = cherrypy.log.error_log
>
> +
>   def is_digit(value):
>       if isinstance(value, int):
>           return True
> @@ -130,3 +135,112 @@ class RollbackContext(object):
>
>       def prependDefer(self, func, *args, **kwargs):
>           self._finally.insert(0, (func, args, kwargs))
> +
> +
> +def name_uid(user):
> +    return pwd.getpwnam(user).pw_uid
> +
> +
> +def run_command(cmd):
> +    try:
> +        proc = subprocess.Popen(cmd, stdout=subprocess.PIPE,
> +                                stderr=subprocess.PIPE)
> +        out, error = proc.communicate()
> +
> +        kimchi_log.debug("Run command '%s'", " ".join(cmd))
> +        if out or error:
> +            kimchi_log.debug("out:\n %s\nerror:\n %s", out, error)
> +    except OSError:

 From subprocess.Popen documentation a ValueError exception can also be 
raised

A ValueError 
<http://docs.python.org/2/library/exceptions.html#exceptions.ValueError> 
will be raised if Popen 
<http://docs.python.org/2/library/subprocess.html#subprocess.Popen> is 
called with invalid arguments.

> +        kimchi_log.debug("Failed to run command %s", " ".join(cmd))
> +        return (None, None, None)
> +    if proc.returncode != 0:
> +        kimchi_log.debug("Cmd '%s' failed, error code: %s", cmd, error)
> +    return (out, error, proc.returncode)
> +
> +
> +def run_setfacl_set_x(path, user="qemu", group=None):

 From my system I have:

alinefm at alinefm:~/kimchi$ getfacl /home/alinefm/kimchi
getfacl: Removing leading '/' from absolute path names
# file: home/alinefm/kimchi
# owner: alinefm
# group: alinefm
user::rwx
group::r-x
other::r-x

So I think the default value for 'group' parameter should be '' (an 
empty string)

Otherwise we will set

group:None:x

> +    set_user = ["setfacl", "--modify", "user:%s:x" % user, path]
> +    set_group = ["setfacl", "--modify", "group:%s:x" % group, path]
> +    out, error, ret = run_command(set_user)
> +    if ret != 0 and group:
> +        out, error, ret = run_command(set_group)
> +    return ret == 0
> +
> +
> +def run_getfacl(path, user="qemu", group=None):

Same as I commented above about default value for 'group' parameter

> +    cmd = ["getfacl", path]
> +    out, error, ret = run_command(cmd)
> +    if out and ret == 0:
> +        res = re.findall("user:%s:..x" % user, out)

> +        res = re.findall("group:%s:..x" % group,
> +                         out) if group and not res else res

Please, do it in a common if statement (it is easier to ready)

> +        return res != []
> +    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)
> +    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):
> +    try:
> +        info = os.stat(path)
> +        mode = info.st_mode
> +        return ((uid == info.st_uid and mode & stat.S_IXUSR == stat.S_IXUSR) or
> +                (uid == info.st_gid and mode & stat.S_IXGRP == stat.S_IXGRP) or
> +                mode & stat.S_IXGRP == stat.S_IXOTH)
> +    except OSError:
> +        kimchi_log.debug("faild to get attribute on %s as user id: %s",
> +                         path, uid)
> +        return False
> +
> +
> +def check_path_permission(path, user='qemu', group=None):
> +    return get_x_on_path(path,
> +                         name_uid(user)) or run_getfacl(path, user, group)
> +
> +
> +def fix_path_permission(path, user='qemu'):
> +    paths = []
> +    while path:
> +        paths.append(path)
> +        if path == "/":
> +            break
> +        path = os.path.dirname(path)
> +
> +    paths.reverse()
> +    for path in paths:
> +        if not (check_path_permission(path) or
> +                run_setfacl_set_x(path) or
> +                set_x_on_path(path)):
> +            return False

We can do it in a single for

# get all paths relates to 'path'
paths = path.split("/")

# remove /
paths = paths[1:]

path = "/"
for p in paths:
     path = os.path.join(path, p)
     if not (check_path_permission(path) or
             run_setfacl_set_x(path) or
             set_x_on_path(path))
         return False

> +    return True
> +
> +
> +def check_path_acl_permission(path, user='qemu', group=None):
> +    return run_getfacl(path, user, group)
> +
> +

> +def fix_path_acl_permission(path, user='qemu'):
> +    paths = []
> +    while path:
> +        paths.append(path)
> +        if path == "/":
> +            break
> +        path = os.path.dirname(path)
> +
> +    paths.reverse()
> +    for path in paths:
> +        if not (run_getfacl(path, user) or run_setfacl_set_x(path, user)):
> +            kimchi_log.debug("faild to set on researchable permission on %s "
> +                             "for user: %s", path, user)
> +            return False

As I commented above, we can do it in a single for statement.

> +    return True

All functions related to file permission could be moved to filepermission.py

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