oslo_policy package¶
Subpackages¶
Submodules¶
oslo_policy.fixture module¶
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class
oslo_policy.fixture.HttpCheckFixture(return_value=True)¶ Bases:
fixtures._fixtures.mockpatch.MockPatchObjectHelps short circuit the external http call
oslo_policy.generator module¶
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oslo_policy.generator.generate_policy(args=None)¶
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oslo_policy.generator.generate_sample(args=None)¶
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oslo_policy.generator.list_redundant(args=None)¶
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oslo_policy.generator.on_load_failure_callback(*args, **kwargs)¶
oslo_policy.opts module¶
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oslo_policy.opts.list_opts()¶ Return a list of oslo.config options available in the library.
The returned list includes all oslo.config options which may be registered at runtime by the library. Each element of the list is a tuple. The first element is the name of the group under which the list of elements in the second element will be registered. A group name of None corresponds to the [DEFAULT] group in config files. This function is also discoverable via the ‘oslo_messaging’ entry point under the ‘oslo.config.opts’ namespace. The purpose of this is to allow tools like the Oslo sample config file generator to discover the options exposed to users by this library.
Returns: a list of (group_name, opts) tuples
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oslo_policy.opts.set_defaults(conf, policy_file=None)¶ Set defaults for configuration variables.
Overrides default options values.
Parameters: - conf (oslo.config.cfg.ConfigOpts) – Configuration object, managed by the caller.
- policy_file (unicode) – The base filename for the file that defines policies.
oslo_policy.policy module¶
Common Policy Engine Implementation
Policies are expressed as a target and an associated rule:
"<target>": <rule>
The target is specific to the service that is conducting policy enforcement. Typically, the target refers to an API call.
For the <rule> part, see Policy Rule Expressions.
Policy Rule Expressions¶
Policy rules can be expressed in one of two forms: a string written in the new policy language or a list of lists. The string format is preferred since it’s easier for most people to understand.
In the policy language, each check is specified as a simple “a:b” pair that is matched to the correct class to perform that check:
TYPE SYNTAX User’s Role role:admin Rules already defined on policy rule:admin_required Against URLs¹ http://my-url.org/check User attributes² project_id:%(target.project.id)s Strings
- <variable>:’xpto2035abc’
- ‘myproject’:<variable>
Literals
- project_id:xpto2035abc
- domain_id:20
- True:%(user.enabled)s
¹URL checking must return True to be valid
²User attributes (obtained through the token): user_id, domain_id or project_id
Conjunction operators and and or are available, allowing for more
expressiveness in crafting policies. For example:
"role:admin or (project_id:%(project_id)s and role:projectadmin)"
The policy language also has the not operator, allowing a richer
policy rule:
"project_id:%(project_id)s and not role:dunce"
Operator precedence is below:
PRECEDENCE TYPE EXPRESSION 4 Grouping (...) 3 Logical NOT not ... 2 Logical AND ... and ... 1 Logical OR ... or ...
Operator with larger precedence number precedes others with smaller numbers.
In the list-of-lists representation, each check inside the innermost list is combined as with an “and” conjunction – for that check to pass, all the specified checks must pass. These innermost lists are then combined as with an “or” conjunction. As an example, take the following rule, expressed in the list-of-lists representation:
[["role:admin"], ["project_id:%(project_id)s", "role:projectadmin"]]
Finally, two special policy checks should be mentioned; the policy
check “@” will always accept an access, and the policy check ”!” will
always reject an access. (Note that if a rule is either the empty
list ([]) or the empty string (""), this is equivalent to the “@”
policy check.) Of these, the ”!” policy check is probably the most useful,
as it allows particular rules to be explicitly disabled.
Generic Checks¶
A generic check is used to perform matching against attributes that are sent along with the API calls. These attributes can be used by the policy engine (on the right side of the expression), by using the following syntax:
<some_attribute>:%(user.id)s
The value on the right-hand side is either a string or resolves to a string using regular Python string substitution. The available attributes and values are dependent on the program that is using the common policy engine.
All of these attributes (related to users, API calls, and context) can be checked against each other or against constants. It is important to note that these attributes are specific to the service that is conducting policy enforcement.
Generic checks can be used to perform policy checks on the following user attributes obtained through a token:
- user_id
- domain_id or project_id (depending on the token scope)
- list of roles held for the given token scope
Note
Some resources which are exposed by the API do not support policy
enforcement by user_id, and only support policy enforcement by project_id. Some global resources do not support policy enforcement by combination of user_id and project_id.
For example, a check on the user_id would be defined as:
user_id:<some_value>
Together with the previously shown example, a complete generic check would be:
user_id:%(user.id)s
It is also possible to perform checks against other attributes that
represent the credentials. This is done by adding additional values to
the creds dict that is passed to the
enforce() method.
Special Checks¶
Special checks allow for more flexibility than is possible using generic
checks. The built-in special check types are role, rule, and http
checks.
Role Check¶
A role check is used to check if a specific role is present in the supplied
credentials. A role check is expressed as:
"role:<role_name>"
Rule Check¶
A rule check is used to
reference another defined rule by its name. This allows for common
checks to be defined once as a reusable rule, which is then referenced
within other rules. It also allows one to define a set of checks as a
more descriptive name to aid in readability of policy. A rule check is
expressed as:
"rule:<rule_name>"
The following example shows a role check that is defined as a rule, which is then used via a rule check:
"admin_required": "role:admin"
"<target>": "rule:admin_required"
HTTP Check¶
An http check is used to make an HTTP request to a remote server to
determine the results of the check. The target and credentials are passed to
the remote server for evaluation. The action is authorized if the remote
server returns a response of True. An http check is expressed as:
"http:<target URI>"
It is expected that the target URI contains a string formatting keyword, where the keyword is a key from the target dictionary. An example of an http check where the name key from the target is used to construct the URL is would be defined as:
"http://server.test/%(name)s"
Default Rule¶
A default rule can be defined, which will be enforced when a rule does
not exist for the target that is being checked. By default, the rule
associated with the rule name of default will be used as the default
rule. It is possible to use a different rule name as the default rule
by setting the policy_default_rule configuration setting to the
desired rule name.
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class
oslo_policy.policy.AndCheck(rules)¶ Bases:
oslo_policy._checks.BaseCheckImplements the “and” logical operator.
A policy check that requires that a list of other checks all return True.
Parameters: rules (list) – rules that will be tested.
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class
oslo_policy.policy.Check(kind, match)¶ Bases:
oslo_policy._checks.BaseCheckA base class to allow for user-defined policy checks.
Parameters: - kind – The kind of the check, i.e., the field before the
:. - match – The match of the check, i.e., the field after the
:.
- kind – The kind of the check, i.e., the field before the
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exception
oslo_policy.policy.DuplicatePolicyError(name)¶ Bases:
exceptions.Exception
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class
oslo_policy.policy.Enforcer(conf, policy_file=None, rules=None, default_rule=None, use_conf=True, overwrite=True)¶ Bases:
objectResponsible for loading and enforcing rules.
Parameters: - conf – A configuration object.
- policy_file – Custom policy file to use, if none is
specified,
conf.oslo_policy.policy_filewill be used. - rules – Default dictionary / Rules to use. It will be
considered just in the first instantiation. If
load_rules()withforce_reload=True,clear()orset_rules()withoverwrite=Trueis called this will be overwritten. - default_rule – Default rule to use, conf.default_rule will be used if none is specified.
- use_conf – Whether to load rules from cache or config file.
- overwrite – Whether to overwrite existing rules when reload rules from config file.
A wrapper around ‘enforce’ that checks for policy registration.
To ensure that a policy being checked has been registered this method should be used rather than enforce. By doing so a project can be sure that all of it’s used policies are registered and therefore available for sample file generation.
The parameters match the enforce method and a description of them can be found there.
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check_rules(raise_on_violation=False)¶ Look for rule definitions that are obviously incorrect.
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clear()¶ Clears
Enforcercontents.This will clear this instances rules, policy’s cache, file cache and policy’s path.
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enforce(rule, target, creds, do_raise=False, exc=None, *args, **kwargs)¶ Checks authorization of a rule against the target and credentials.
Parameters: - rule (string or
BaseCheck) – The rule to evaluate. - target (dict) – As much information about the object being operated on as possible.
- creds (dict) – As much information about the user performing the action as possible.
- do_raise – Whether to raise an exception or not if check fails.
- exc – Class of the exception to raise if the check fails.
Any remaining arguments passed to
enforce()(both positional and keyword arguments) will be passed to the exception class. If not specified,PolicyNotAuthorizedwill be used.
Returns: Falseif the policy does not allow the action and exc is not provided; otherwise, returns a value that evaluates toTrue. Note: for rules using the “case” expression, thisTruevalue will be the specified string from the expression.- rule (string or
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load_rules(force_reload=False)¶ Loads policy_path’s rules.
Policy file is cached and will be reloaded if modified.
Parameters: force_reload – Whether to reload rules from config file.
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register_default(default)¶ Registers a RuleDefault.
Adds a RuleDefault to the list of registered rules. Rules must be registered before using the Enforcer.authorize method.
Parameters: default – A RuleDefault object to register.
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register_defaults(defaults)¶ Registers a list of RuleDefaults.
Adds each RuleDefault to the list of registered rules. Rules must be registered before using the Enforcer.authorize method.
Parameters: default – A list of RuleDefault objects to register.
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exception
oslo_policy.policy.InvalidDefinitionError(names)¶ Bases:
exceptions.Exception
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class
oslo_policy.policy.NotCheck(rule)¶ Bases:
oslo_policy._checks.BaseCheckImplements the “not” logical operator.
A policy check that inverts the result of another policy check.
Parameters: rule – The rule to negate.
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class
oslo_policy.policy.OrCheck(rules)¶ Bases:
oslo_policy._checks.BaseCheckImplements the “or” operator.
A policy check that requires that at least one of a list of other checks returns
True.Parameters: rules – A list of rules that will be tested. -
add_check(rule)¶ Adds rule to be tested.
Allows addition of another rule to the list of rules that will be tested. Returns the OrCheck object for convenience.
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exception
oslo_policy.policy.PolicyNotAuthorized(rule, target, creds)¶ Bases:
exceptions.ExceptionDefault exception raised for policy enforcement failure.
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exception
oslo_policy.policy.PolicyNotRegistered(name)¶ Bases:
exceptions.Exception
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class
oslo_policy.policy.RuleCheck(kind, match)¶ Bases:
oslo_policy._checks.CheckRecursively checks credentials based on the defined rules.
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class
oslo_policy.policy.RuleDefault(name, check_str, description=None)¶ Bases:
objectA class for holding policy definitions.
It is required to supply a name and value at creation time. It is encouraged to also supply a description to assist operators.
Parameters: - name – The name of the policy. This is used when referencing it from another rule or during policy enforcement.
- check_str – The policy. This is a string defining a policy that conforms to the policy language outlined at the top of the file.
- description – A plain text description of the policy. This will be used to comment sample policy files for use by deployers.
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class
oslo_policy.policy.Rules(rules=None, default_rule=None)¶ Bases:
dictA store for rules. Handles the default_rule setting directly.
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classmethod
from_dict(rules_dict, default_rule=None)¶ Allow loading of rule data from a dictionary.
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classmethod
load(data, default_rule=None)¶ Allow loading of YAML/JSON rule data.
New in version 1.5.0.
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classmethod
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oslo_policy.policy.parse_file_contents(data)¶ Parse the raw contents of a policy file.
Parses the contents of a policy file which currently can be in either yaml or json format. Both can be parsed as yaml.
Parameters: data – A string containing the contents of a policy file. Returns: A dict of the form {‘policy_name1’: ‘policy1’, ‘policy_name2’: ‘policy2,...}
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oslo_policy.policy.register(name, func=None)¶ Register a function or
Checkclass as a policy check.Parameters: - name – Gives the name of the check type, e.g., “rule”,
“role”, etc. If name is
None, a default check type will be registered. - func – If given, provides the function or class to register. If not given, returns a function taking one argument to specify the function or class to register, allowing use as a decorator.
- name – Gives the name of the check type, e.g., “rule”,
“role”, etc. If name is
oslo_policy.shell module¶
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oslo_policy.shell.main()¶
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oslo_policy.shell.tool(policy_file, access_file, apply_rule, is_admin=False)¶
oslo_policy.sphinxpolicygen module¶
Generate a sample policy file.
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oslo_policy.sphinxpolicygen.generate_sample(app)¶ Generate a sample policy file.
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oslo_policy.sphinxpolicygen.setup(app)¶