simulate-custom-policy¶

Description¶

Simulate how a set of IAM policies and optionally a resource-based policy works with a list of API operations and AWS resources to determine the policies’ effective permissions. The policies are provided as strings.

The simulation does not perform the API operations; it only checks the authorization to determine if the simulated policies allow or deny the operations.

If you want to simulate existing policies that are attached to an IAM user, group, or role, use SimulatePrincipalPolicy instead.

Context keys are variables that are maintained by AWS and its services and which provide details about the context of an API query request. You can use the Condition element of an IAM policy to evaluate context keys. To get the list of context keys that the policies require for correct simulation, use GetContextKeysForCustomPolicy .

If the output is long, you can use MaxItems and Marker parameters to paginate the results.

Synopsis¶

  simulate-custom-policy
--policy-input-list <value>
[--permissions-boundary-policy-input-list <value>]
--action-names <value>
[--resource-arns <value>]
[--resource-policy <value>]
[--resource-owner <value>]
[--caller-arn <value>]
[--context-entries <value>]
[--resource-handling-option <value>]
[--max-items <value>]
[--cli-input-json | --cli-input-yaml]
[--starting-token <value>]
[--page-size <value>]
[--generate-cli-skeleton <value>]
[--cli-auto-prompt <value>]

Options¶

--policy-input-list (list)

A list of policy documents to include in the simulation. Each document is specified as a string containing the complete, valid JSON text of an IAM policy. Do not include any resource-based policies in this parameter. Any resource-based policy must be submitted with the ResourcePolicy parameter. The policies cannot be “scope-down” policies, such as you could include in a call to GetFederationToken or one of the AssumeRole API operations. In other words, do not use policies designed to restrict what a user can do while using the temporary credentials.

The regex pattern used to validate this parameter is a string of characters consisting of the following:

Any printable ASCII character ranging from the space character (\u0020 ) through the end of the ASCII character range

The printable characters in the Basic Latin and Latin-1 Supplement character set (through \u00FF )

The special characters tab (\u0009 ), line feed (\u000A ), and carriage return (\u000D )

(string)

Syntax:

"string" "string" ...

--permissions-boundary-policy-input-list (list)

The IAM permissions boundary policy to simulate. The permissions boundary sets the maximum permissions that an IAM entity can have. You can input only one permissions boundary when you pass a policy to this operation. For more information about permissions boundaries, see Permissions Boundaries for IAM Entities in the IAM User Guide . The policy input is specified as a string that contains the complete, valid JSON text of a permissions boundary policy.

The regex pattern used to validate this parameter is a string of characters consisting of the following:

Any printable ASCII character ranging from the space character (\u0020 ) through the end of the ASCII character range

The printable characters in the Basic Latin and Latin-1 Supplement character set (through \u00FF )

The special characters tab (\u0009 ), line feed (\u000A ), and carriage return (\u000D )

(string)

Syntax:

"string" "string" ...

--action-names (list)

A list of names of API operations to evaluate in the simulation. Each operation is evaluated against each resource. Each operation must include the service identifier, such as iam:CreateUser . This operation does not support using wildcards (*) in an action name.

(string)

Syntax:

"string" "string" ...

--resource-arns (list)

A list of ARNs of AWS resources to include in the simulation. If this parameter is not provided, then the value defaults to * (all resources). Each API in the ActionNames parameter is evaluated for each resource in this list. The simulation determines the access result (allowed or denied) of each combination and reports it in the response.

The simulation does not automatically retrieve policies for the specified resources. If you want to include a resource policy in the simulation, then you must include the policy as a string in the ResourcePolicy parameter.

If you include a ResourcePolicy , then it must be applicable to all of the resources included in the simulation or you receive an invalid input error.

For more information about ARNs, see Amazon Resource Names (ARNs) and AWS Service Namespaces in the AWS General Reference .

(string)

Syntax:

"string" "string" ...

--resource-policy (string)

A resource-based policy to include in the simulation provided as a string. Each resource in the simulation is treated as if it had this policy attached. You can include only one resource-based policy in a simulation.

The regex pattern used to validate this parameter is a string of characters consisting of the following:

Any printable ASCII character ranging from the space character (\u0020 ) through the end of the ASCII character range

The printable characters in the Basic Latin and Latin-1 Supplement character set (through \u00FF )

The special characters tab (\u0009 ), line feed (\u000A ), and carriage return (\u000D )

--resource-owner (string)

An ARN representing the AWS account ID that specifies the owner of any simulated resource that does not identify its owner in the resource ARN. Examples of resource ARNs include an S3 bucket or object. If ResourceOwner is specified, it is also used as the account owner of any ResourcePolicy included in the simulation. If the ResourceOwner parameter is not specified, then the owner of the resources and the resource policy defaults to the account of the identity provided in CallerArn . This parameter is required only if you specify a resource-based policy and account that owns the resource is different from the account that owns the simulated calling user CallerArn .

The ARN for an account uses the following syntax: arn:aws:iam::*AWS-account-ID* :root . For example, to represent the account with the 112233445566 ID, use the following ARN: arn:aws:iam::112233445566-ID:root .

--caller-arn (string)

The ARN of the IAM user that you want to use as the simulated caller of the API operations. CallerArn is required if you include a ResourcePolicy so that the policy’s Principal element has a value to use in evaluating the policy.

You can specify only the ARN of an IAM user. You cannot specify the ARN of an assumed role, federated user, or a service principal.

--context-entries (list)

A list of context keys and corresponding values for the simulation to use. Whenever a context key is evaluated in one of the simulated IAM permissions policies, the corresponding value is supplied.

(structure)

Contains information about a condition context key. It includes the name of the key and specifies the value (or values, if the context key supports multiple values) to use in the simulation. This information is used when evaluating the Condition elements of the input policies.

This data type is used as an input parameter to SimulateCustomPolicy and SimulatePrincipalPolicy .

ContextKeyName -> (string)

The full name of a condition context key, including the service prefix. For example, aws:SourceIp or s3:VersionId .

ContextKeyValues -> (list)

The value (or values, if the condition context key supports multiple values) to provide to the simulation when the key is referenced by a Condition element in an input policy.

(string)

ContextKeyType -> (string)

The data type of the value (or values) specified in the ContextKeyValues parameter.

Shorthand Syntax:

ContextKeyName=string,ContextKeyValues=string,string,ContextKeyType=string ...

JSON Syntax:

[
  {
    "ContextKeyName": "string",
    "ContextKeyValues": ["string", ...],
    "ContextKeyType": "string"|"stringList"|"numeric"|"numericList"|"boolean"|"booleanList"|"ip"|"ipList"|"binary"|"binaryList"|"date"|"dateList"
  }
  ...
]

--resource-handling-option (string)

Specifies the type of simulation to run. Different API operations that support resource-based policies require different combinations of resources. By specifying the type of simulation to run, you enable the policy simulator to enforce the presence of the required resources to ensure reliable simulation results. If your simulation does not match one of the following scenarios, then you can omit this parameter. The following list shows each of the supported scenario values and the resources that you must define to run the simulation.

Each of the EC2 scenarios requires that you specify instance, image, and security-group resources. If your scenario includes an EBS volume, then you must specify that volume as a resource. If the EC2 scenario includes VPC, then you must supply the network-interface resource. If it includes an IP subnet, then you must specify the subnet resource. For more information on the EC2 scenario options, see Supported Platforms in the Amazon EC2 User Guide .

EC2-Classic-InstanceStore instance, image, security-group

EC2-Classic-EBS instance, image, security-group, volume

EC2-VPC-InstanceStore instance, image, security-group, network-interface

EC2-VPC-InstanceStore-Subnet instance, image, security-group, network-interface, subnet

EC2-VPC-EBS instance, image, security-group, network-interface, volume

EC2-VPC-EBS-Subnet instance, image, security-group, network-interface, subnet, volume

--max-items (integer)

The total number of items to return in the command’s output. If the total number of items available is more than the value specified, a NextToken is provided in the command’s output. To resume pagination, provide the NextToken value in the starting-token argument of a subsequent command. Do not use the NextToken response element directly outside of the AWS CLI.

For usage examples, see Pagination in the AWS Command Line Interface User Guide .

--cli-input-json | --cli-input-yaml (string) Reads arguments from the JSON string provided. The JSON string follows the format provided by --generate-cli-skeleton. If other arguments are provided on the command line, those values will override the JSON-provided values. It is not possible to pass arbitrary binary values using a JSON-provided value as the string will be taken literally. This may not be specified along with --cli-input-yaml.

--starting-token (string)

A token to specify where to start paginating. This is the NextToken from a previously truncated response.

For usage examples, see Pagination in the AWS Command Line Interface User Guide .

--page-size (integer)

The size of each page to get in the AWS service call. This does not affect the number of items returned in the command’s output. Setting a smaller page size results in more calls to the AWS service, retrieving fewer items in each call. This can help prevent the AWS service calls from timing out.

For usage examples, see Pagination in the AWS Command Line Interface User Guide .

--generate-cli-skeleton (string) Prints a JSON skeleton to standard output without sending an API request. If provided with no value or the value input, prints a sample input JSON that can be used as an argument for --cli-input-json. Similarly, if provided yaml-input it will print a sample input YAML that can be used with --cli-input-yaml. If provided with the value output, it validates the command inputs and returns a sample output JSON for that command.

--cli-auto-prompt (boolean) Automatically prompt for CLI input parameters.

See ‘aws help’ for descriptions of global parameters.

Examples¶

To simulate the effects of all IAM policies associated with an IAM user or role

The following simulate-custom-policy shows how to provide both the policy and define variable values and simulate an API call to see if it is allowed or denied. The following example shows a policy that enables database access only after a specified date and time. The simulation succeeds because the simulated actions and the specified aws:CurrentTime variable all match the requirements of the policy.

aws iam simulate-custom-policy \
    --policy-input-list '{"Version":"2012-10-17","Statement":{"Effect":"Allow","Action":"dynamodb:*","Resource":"*","Condition":{"DateGreaterThan":{"aws:CurrentTime":"2018-08-16T12:00:00Z"}}}}' \
    --action-names dynamodb:CreateBackup \
    --context-entries "ContextKeyName='aws:CurrentTime',ContextKeyValues='2019-04-25T11:00:00Z',ContextKeyType=date"

Output:

{
    "EvaluationResults": [
        {
            "EvalActionName": "dynamodb:CreateBackup",
            "EvalResourceName": "*",
            "EvalDecision": "allowed",
            "MatchedStatements": [
                {
                    "SourcePolicyId": "PolicyInputList.1",
                    "StartPosition": {
                        "Line": 1,
                        "Column": 38
                    },
                    "EndPosition": {
                        "Line": 1,
                        "Column": 167
                    }
                }
            ],
            "MissingContextValues": []
        }
    ]
}

The following simulate-custom-policy example shows the results of simulating a command that is prohibited by the policy. In this example, the provided date is before that required by the policy’s condition.

aws iam simulate-custom-policy \
    --policy-input-list '{"Version":"2012-10-17","Statement":{"Effect":"Allow","Action":"dynamodb:*","Resource":"*","Condition":{"DateGreaterThan":{"aws:CurrentTime":"2018-08-16T12:00:00Z"}}}}' \
    --action-names dynamodb:CreateBackup \
    --context-entries "ContextKeyName='aws:CurrentTime',ContextKeyValues='2014-04-25T11:00:00Z',ContextKeyType=date"

Output:

{
    "EvaluationResults": [
        {
            "EvalActionName": "dynamodb:CreateBackup",
            "EvalResourceName": "*",
            "EvalDecision": "implicitDeny",
            "MatchedStatements": [],
            "MissingContextValues": []
        }
    ]
}

For more information, see Testing IAM Policies with the IAM Policy Simulator in the AWS IAM User Guide

Output¶

EvaluationResults -> (list)

The results of the simulation.

(structure)

Contains the results of a simulation.

This data type is used by the return parameter of `` SimulateCustomPolicy `` and `` SimulatePrincipalPolicy `` .

EvalActionName -> (string)

The name of the API operation tested on the indicated resource.

EvalResourceName -> (string)

The ARN of the resource that the indicated API operation was tested on.

EvalDecision -> (string)

The result of the simulation.

MatchedStatements -> (list)

A list of the statements in the input policies that determine the result for this scenario. Remember that even if multiple statements allow the operation on the resource, if only one statement denies that operation, then the explicit deny overrides any allow. In addition, the deny statement is the only entry included in the result.

(structure)

Contains a reference to a Statement element in a policy document that determines the result of the simulation.

This data type is used by the MatchedStatements member of the `` EvaluationResult `` type.

SourcePolicyId -> (string)

The identifier of the policy that was provided as an input.

SourcePolicyType -> (string)

The type of the policy.

StartPosition -> (structure)

The row and column of the beginning of the Statement in an IAM policy.

Line -> (integer)

The line containing the specified position in the document.

Column -> (integer)

The column in the line containing the specified position in the document.

EndPosition -> (structure)

The row and column of the end of a Statement in an IAM policy.

Line -> (integer)

The line containing the specified position in the document.

Column -> (integer)

The column in the line containing the specified position in the document.

MissingContextValues -> (list)

A list of context keys that are required by the included input policies but that were not provided by one of the input parameters. This list is used when the resource in a simulation is “*”, either explicitly, or when the ResourceArns parameter blank. If you include a list of resources, then any missing context values are instead included under the ResourceSpecificResults section. To discover the context keys used by a set of policies, you can call GetContextKeysForCustomPolicy or GetContextKeysForPrincipalPolicy .

(string)

OrganizationsDecisionDetail -> (structure)

A structure that details how Organizations and its service control policies affect the results of the simulation. Only applies if the simulated user’s account is part of an organization.

AllowedByOrganizations -> (boolean)

Specifies whether the simulated operation is allowed by the Organizations service control policies that impact the simulated user’s account.

PermissionsBoundaryDecisionDetail -> (structure)

Contains information about the effect that a permissions boundary has on a policy simulation when the boundary is applied to an IAM entity.

AllowedByPermissionsBoundary -> (boolean)

Specifies whether an action is allowed by a permissions boundary that is applied to an IAM entity (user or role). A value of true means that the permissions boundary does not deny the action. This means that the policy includes an Allow statement that matches the request. In this case, if an identity-based policy also allows the action, the request is allowed. A value of false means that either the requested action is not allowed (implicitly denied) or that the action is explicitly denied by the permissions boundary. In both of these cases, the action is not allowed, regardless of the identity-based policy.

EvalDecisionDetails -> (map)

Additional details about the results of the cross-account evaluation decision. This parameter is populated for only cross-account simulations. It contains a brief summary of how each policy type contributes to the final evaluation decision.

If the simulation evaluates policies within the same account and includes a resource ARN, then the parameter is present but the response is empty. If the simulation evaluates policies within the same account and specifies all resources (* ), then the parameter is not returned.

When you make a cross-account request, AWS evaluates the request in the trusting account and the trusted account. The request is allowed only if both evaluations return true . For more information about how policies are evaluated, see Evaluating Policies Within a Single Account .

If an AWS Organizations SCP included in the evaluation denies access, the simulation ends. In this case, policy evaluation does not proceed any further and this parameter is not returned.

key -> (string)

value -> (string)

ResourceSpecificResults -> (list)

The individual results of the simulation of the API operation specified in EvalActionName on each resource.

(structure)

Contains the result of the simulation of a single API operation call on a single resource.

This data type is used by a member of the EvaluationResult data type.

EvalResourceName -> (string)

The name of the simulated resource, in Amazon Resource Name (ARN) format.

EvalResourceDecision -> (string)

The result of the simulation of the simulated API operation on the resource specified in EvalResourceName .

MatchedStatements -> (list)

A list of the statements in the input policies that determine the result for this part of the simulation. Remember that even if multiple statements allow the operation on the resource, if any statement denies that operation, then the explicit deny overrides any allow. In addition, the deny statement is the only entry included in the result.

(structure)

Contains a reference to a Statement element in a policy document that determines the result of the simulation.

This data type is used by the MatchedStatements member of the `` EvaluationResult `` type.

SourcePolicyId -> (string)

The identifier of the policy that was provided as an input.

SourcePolicyType -> (string)

The type of the policy.

StartPosition -> (structure)

The row and column of the beginning of the Statement in an IAM policy.

Line -> (integer)

The line containing the specified position in the document.

Column -> (integer)

The column in the line containing the specified position in the document.

EndPosition -> (structure)

The row and column of the end of a Statement in an IAM policy.

Line -> (integer)

The line containing the specified position in the document.

Column -> (integer)

The column in the line containing the specified position in the document.

MissingContextValues -> (list)

A list of context keys that are required by the included input policies but that were not provided by one of the input parameters. This list is used when a list of ARNs is included in the ResourceArns parameter instead of “*”. If you do not specify individual resources, by setting ResourceArns to “*” or by not including the ResourceArns parameter, then any missing context values are instead included under the EvaluationResults section. To discover the context keys used by a set of policies, you can call GetContextKeysForCustomPolicy or GetContextKeysForPrincipalPolicy .

(string)

EvalDecisionDetails -> (map)

Additional details about the results of the evaluation decision on a single resource. This parameter is returned only for cross-account simulations. This parameter explains how each policy type contributes to the resource-specific evaluation decision.

key -> (string)

value -> (string)

PermissionsBoundaryDecisionDetail -> (structure)

Contains information about the effect that a permissions boundary has on a policy simulation when that boundary is applied to an IAM entity.

AllowedByPermissionsBoundary -> (boolean)

Specifies whether an action is allowed by a permissions boundary that is applied to an IAM entity (user or role). A value of true means that the permissions boundary does not deny the action. This means that the policy includes an Allow statement that matches the request. In this case, if an identity-based policy also allows the action, the request is allowed. A value of false means that either the requested action is not allowed (implicitly denied) or that the action is explicitly denied by the permissions boundary. In both of these cases, the action is not allowed, regardless of the identity-based policy.

IsTruncated -> (boolean)

A flag that indicates whether there are more items to return. If your results were truncated, you can make a subsequent pagination request using the Marker request parameter to retrieve more items. Note that IAM might return fewer than the MaxItems number of results even when there are more results available. We recommend that you check IsTruncated after every call to ensure that you receive all your results.

Marker -> (string)

When IsTruncated is true , this element is present and contains the value to use for the Marker parameter in a subsequent pagination request.

Table of Contents

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User Guide

simulate-custom-policy¶

Description¶

Synopsis¶

Options¶

Examples¶

Output¶