Aside from manually managing access using custom code, Odoo provides two main data-driven mechanisms to manage or restrict access to data.
Both mechanisms are linked to specific users through groups: a user belongs to any number of groups, and security mechanisms are associated to groups, thus applying security mechamisms to users.
Access Control
Managed by the ir.model.access
records, defines access to a whole model.
Each access control has a model to which it grants permissions, the permissions it grants and optionally a group.
Access controls are additive, for a given model a user has access all permissions granted to any of its groups: if the user belongs to one group which allows writing and another which allows deleting, they can both write and delete.
If no group is specified, the access control applies to all users, otherwise it only applies to the members of the given group.
Available permissions are creation (perm_create
), searching and reading
(perm_read
), updating existing records (perm_write
) and deleting
existing records (perm_unlink
)
Record Rules
Record rules are conditions that records must satisfy for an operation (create, read, update or delete) to be allowed. It is applied record-by-record after access control has been applied.
A record rule has:
- a model on which it applies
- a set of permissions to which it applies (e.g. if
perm_read
is set, the rule will only be checked when reading a record) - a set of user groups to which the rule applies, if no group is specified the rule is global
- a domain used to check whether a given record
matches the rule (and is accessible) or does not (and is not accessible).
The domain is evaluated with two variables in context:
user
is the current user’s record andtime
is the time module
Global rules and group rules (rules restricted to specific groups versus groups applying to all users) are used quite differently:
- Global rules are subtractive, they must all be matched for a record to be accessible
- Group rules are additive, if any of them matches (and all global rules match) then the record is accessible
This means the first group rule restricts access, but any further group rule expands it, while global rules can only ever restrict access (or have no effect).
Warning
record rules do not apply to the Superuser account
Field Access
An ORM Field
can have a groups
attribute
providing a list of groups (as a comma-separated string of
external identifiers).
If the current user is not in one of the listed groups, he will not have access to the field:
- restricted fields are automatically removed from requested views
- restricted fields are removed from
fields_get()
responses - attempts to (explicitly) read from or write to restricted fields results in an access error
Security Pitfalls
As a developer, it is important to understand the security mechanisms and avoid common mistakes leading to insecure code.
Unsafe Public Methods
Any public method can be executed via a RPC call with the chosen parameters. The methods
starting with a _
are not callable from an action button or external API.
On public methods, the record on which a method is executed and the parameters can not be trusted, ACL being only verified during CRUD operations.
# this method is public and its arguments can not be trusted
def action_done(self):
if self.state == "draft" and self.user_has_groups('base.manager'):
self._set_state("done")
# this method is private and can only be called from other python methods
def _set_state(self, new_state):
self.sudo().write({"state": new_state})
Making a method private is obviously not enough and care must be taken to use it properly.
Bypassing the ORM
You should never use the database cursor directly when the ORM can do the same
thing! By doing so you are bypassing all the ORM features, possibly the
automated behaviours like translations, invalidation of fields, active
,
access rights and so on.
And chances are that you are also making the code harder to read and probably less secure.
# very very wrong
self.env.cr.execute('SELECT id FROM auction_lots WHERE auction_id in (' + ','.join(map(str, ids))+') AND state=%s AND obj_price > 0', ('draft',))
auction_lots_ids = [x[0] for x in self.env.cr.fetchall()]
# no injection, but still wrong
self.env.cr.execute('SELECT id FROM auction_lots WHERE auction_id in %s '\
'AND state=%s AND obj_price > 0', (tuple(ids), 'draft',))
auction_lots_ids = [x[0] for x in self.env.cr.fetchall()]
# better
auction_lots_ids = self.search([('auction_id','in',ids), ('state','=','draft'), ('obj_price','>',0)])
SQL injections
Care must be taken not to introduce SQL injections vulnerabilities when using
manual SQL queries. The vulnerability is present when user input is either
incorrectly filtered or badly quoted, allowing an attacker to introduce
undesirable clauses to a SQL query (such as circumventing filters or
executing UPDATE
or DELETE
commands).
The best way to be safe is to never, NEVER use Python string concatenation (+) or string parameters interpolation (%) to pass variables to a SQL query string.
The second reason, which is almost as important, is that it is the job of the database abstraction layer (psycopg2) to decide how to format query parameters, not your job! For example psycopg2 knows that when you pass a list of values it needs to format them as a comma-separated list, enclosed in parentheses !
# the following is very bad:
# - it's a SQL injection vulnerability
# - it's unreadable
# - it's not your job to format the list of ids
self.env.cr.execute('SELECT distinct child_id FROM account_account_consol_rel ' +
'WHERE parent_id IN ('+','.join(map(str, ids))+')')
# better
self.env.cr.execute('SELECT DISTINCT child_id '\
'FROM account_account_consol_rel '\
'WHERE parent_id IN %s',
(tuple(ids),))
This is very important, so please be careful also when refactoring, and most importantly do not copy these patterns!
Here is a memorable example to help you remember what the issue is about (but do not copy the code there). Before continuing, please be sure to read the online documentation of pyscopg2 to learn of to use it properly:
Unescaped field content
When rendering content using JavaScript and XML, one may be tempted to use
a t-raw
to display rich-text content. This should be avoided as a frequent
XSS vector.
It is very hard to control the integrity of the data from the computation until
the final integration in the browser DOM. A t-raw
that is correctly escaped
at the time of introduction may no longer be safe at the next bugfix or
refactoring.
QWeb.render('insecure_template', {
info_message: "You have an <strong>important</strong> notification",
})
<div t-name="insecure_template">
<div id="information-bar"><t t-raw="info_message" /></div>
</div>
The above code may feel safe as the message content is controlled but is a bad practice that may lead to unexpected security vulnerabilities once this code evolves in the future.
// XSS possible with unescaped user provided content !
QWeb.render('insecure_template', {
info_message: "You have an <strong>important</strong> notification on " \
+ "the product <strong>" + product.name + "</strong>",
})
While formatting the template differently would prevent such vulnerabilities.
QWeb.render('secure_template', {
message: "You have an important notification on the product:",
subject: product.name
})
<div t-name="secure_template">
<div id="information-bar">
<div class="info"><t t-esc="message" /></div>
<div class="subject"><t t-esc="subject" /></div>
</div>
</div>
.subject {
font-weight: bold;
}
Escaping vs Sanitizing
Important
Escaping is always 100% mandatory when you mix data and code, no matter how safe the data
Escaping converts TEXT to CODE. It is absolutely mandatory to do it
every time you mix DATA/TEXT with CODE (e.g. generating HTML or python code
to be evaluated inside a safe_eval
), because CODE always requires TEXT to
be encoded. It is critical for security, but it’s also a question of
correctness. Even when there is no security risk (because the text is 100%
guarantee to be safe or trusted), it is still required (e.g. to avoid breaking
the layout in generated HTML).
Escaping will never break any feature, as long as the developer identifies which variable contains TEXT and which contains CODE.
>>> from odoo.tools import html_escape, html_sanitize
>>> data = "<R&D>" # `data` is some TEXT coming from somewhere
# Escaping turns it into CODE, good!
>>> code = html_escape(data)
>>> code
'<R&D>'
# Now you can mix it with other code...
>>> self.message_post(body="<strong>%s</strong>" % code)
Sanitizing converts CODE to SAFER CODE (but not necessary safe code). It does not work on TEXT. Sanitizing is only necessary when CODE is untrusted, because it comes in full or in part from some user-provided data. If the user-provided data is in the form of TEXT (e.g. the content from a form filled by a user), and if that data was correctly escaped before putting it in CODE, then sanitizing is useless (but can still be done). If however, the user-provided data was not escaped, then sanitizing will not work as expected.
# Sanitizing without escaping is BROKEN: data is corrupted!
>>> html_sanitize(data)
''
# Sanitizing *after* escaping is OK!
>>> html_sanitize(code)
'<p><R&D></p>'
Sanitizing can break features, depending on whether the CODE is expected to
contain patterns that are not safe. That’s why fields.Html
and
tools.html_sanitize()
have options to fine-tune the level of sanitization for
styles, etc. Those options have to be carefully considered depending on where
the data comes from, and the desired features. The sanitization safety is
balanced against sanitization breakages: the safer the sanitisation the more
likely it is to break things.
>>code = "<p class='text-warning'>Important Information</p>"
# this will remove the style, which may break features
# but is necessary if the source is untrusted
>> html_sanitize(code, strip_classes=True)
'<p>Important Information</p>'
Evaluating content
Some may want to eval
to parse user provided content. Using eval
should
be avoided at all cost. A safer, sandboxed, method safe_eval
can be used instead but still gives tremendous capabilities to the user running
it and must be reserved for trusted privileged users only as it breaks the
barrier between code and data.
# very bad
domain = eval(self.filter_domain)
return self.search(domain)
# better but still not recommended
from odoo.tools import safe_eval
domain = safe_eval(self.filter_domain)
return self.search(domain)
# good
from ast import literal_eval
domain = literal_eval(self.filter_domain)
return self.search(domain)
Parsing content does not need eval
Language | Data type | Suitable parser |
---|---|---|
Python | int, float, etc. | int(), float() |
Javascript | int, float, etc. | parseInt(), parseFloat() |
Python | dict | json.loads(), ast.literal_eval() |
Javascript | object, list, etc. | JSON.parse() |
Accessing object attributes
If the values of a record needs to be retrieved or modified dynamically, one may
want to use the getattr
and setattr
methods.
# unsafe retrieval of a field value
def _get_state_value(self, res_id, state_field):
record = self.sudo().browse(res_id)
return getattr(record, state_field, False)
This code is however not safe as it allows to access any property of the record, including private attributes or methods.
The __getitem__
of a recordset has been defined and accessing a dynamic
field value can be easily achieved safely:
# better retrieval of a field value
def _get_state_value(self, res_id, state_field):
record = self.sudo().browse(res_id)
return record[state_field]
The above method is obviously still too optimistic and additional verifications on the record id and field value must be done.