fix: sanitize AWS session tags (#20)

* Sanitize github actor tag

* Add some tests

* Sanitize Github actions workflow name

* Change sanitization character to an asterisk

* Update readme about assuming a role

* Tidy up assume role readme entry more

* Align sanitize spelling to use -ize

* typo: environement -> environment

README.md

@@ -26,6 +26,39 @@ We recommend following [Amazon IAM best practices](https://docs.aws.amazon.com/I
 * [Rotate the credentials](https://docs.aws.amazon.com/IAM/latest/UserGuide/best-practices.html#rotate-credentials) used in GitHub Actions workflows regularly.
 * [Monitor the activity](https://docs.aws.amazon.com/IAM/latest/UserGuide/best-practices.html#keep-a-log) of the credentials used in GitHub Actions workflows.
 
+## Assuming a role
+If you would like to use the credentials you provide to this action to assume a role, you can do so by specifying the role ARN in `role-to-assume`.
+The role credentials will then be output instead of the ones you have provided.  
+The default session duration is 6 hours, but if you would like to adjust this you can pass a duration to `role-duration-seconds`.
+
+Example:
+```yaml
+    - name: Configure AWS Credentials
+      uses: aws-actions/configure-aws-credentials@v1
+      with:
+        aws-access-key-id: ${{ secrets.AWS_ACCESS_KEY_ID }}
+        aws-secret-access-key: ${{ secrets.AWS_SECRET_ACCESS_KEY }}
+        aws-region: us-east-2
+        role-to-assume: arn:aws:iam::123456789100:role/role-to-assume
+        role-duration-seconds: 1200
+```
+
+### Session tagging
+The session will have the name "GitHubActions" and be tagged with the following tags:  
+(`GITHUB_` environment variable definitions can be [found here](https://help.github.com/en/actions/automating-your-workflow-with-github-actions/using-environment-variables#default-environment-variables))
+
+| Key | Value|
+| --- | --- |
+| GitHub | "Actions" |
+| Repository | GITHUB_REPOSITORY |
+| Workflow | GITHUB_WORKFLOW |
+| Action | GITHUB_ACTION |
+| Actor | GITHUB_ACTOR |
+| Branch | GITHUB_REF |
+| Commit | GITHUB_SHA |
+
+_Note: all tag values must conform to [the requirements](https://docs.aws.amazon.com/STS/latest/APIReference/API_Tag.html). Particularly, `GITHUB_WORKFLOW` will be truncated if it's too long. If `GITHUB_ACTOR` or `GITHUB_WORKFLOW` contain invalid charcters, the characters will be replaced with an '*'._
+
 ## License Summary
 
 This code is made available under the MIT license.

index.js

@@ -7,6 +7,8 @@ const util = require('util');
 // That seems like a reasonable default to use if no role duration is defined.
 const MAX_ACTION_RUNTIME = 6 * 3600;
 const USER_AGENT = 'configure-aws-credentials-for-github-actions';
+const MAX_TAG_VALUE_LENGTH = 256;
+const SANITIZATION_CHARACTER = '*'
 
 async function assumeRole(params) {
   // Assume a role to get short-lived credentials using longer-lived credentials.
@@ -36,9 +38,9 @@ async function assumeRole(params) {
     Tags: [
       {Key: 'GitHub', Value: 'Actions'},
       {Key: 'Repository', Value: GITHUB_REPOSITORY},
-      {Key: 'Workflow', Value: GITHUB_WORKFLOW},
+      {Key: 'Workflow', Value: sanitizeGithubWorkflowName(GITHUB_WORKFLOW)},
       {Key: 'Action', Value: GITHUB_ACTION},
-      {Key: 'Actor', Value: GITHUB_ACTOR},
+      {Key: 'Actor', Value: sanitizeGithubActor(GITHUB_ACTOR)},
       {Key: 'Branch', Value: GITHUB_REF},
       {Key: 'Commit', Value: GITHUB_SHA},
     ]
@@ -53,6 +55,21 @@ async function assumeRole(params) {
   });
 }
 
+function sanitizeGithubActor(actor) {
+  // In some circumstances the actor may contain square brackets. For example, if they're a bot ('[bot]')
+  // Square brackets are not allowed in AWS session tags
+  return actor.replace(/\[|\]/g, SANITIZATION_CHARACTER)
+}
+
+function sanitizeGithubWorkflowName(name) {
+  // Workflow names can be almost any valid UTF-8 string, but tags are more restrictive.
+  // This replaces anything not conforming to the tag restrictions by inverting the regular expression.
+  // See the AWS documentation for constraint specifics https://docs.aws.amazon.com/STS/latest/APIReference/API_Tag.html.
+  const nameWithoutSpecialCharacters = name.replace(/[^\p{L}\p{Z}\p{N}_.:/=+-@]/gu, SANITIZATION_CHARACTER);
+  const nameTruncated = nameWithoutSpecialCharacters.slice(0, MAX_TAG_VALUE_LENGTH)
+  return nameTruncated
+}
+
 function exportCredentials(params){
   // Configure the AWS CLI and AWS SDKs using environment variables and set them as secrets.
   // Setting the credentials as secrets masks them in Github Actions logs

index.test.js

@@ -19,10 +19,11 @@ const ENVIRONMENT_VARIABLE_OVERRIDES = {
     GITHUB_REPOSITORY: 'MY-REPOSITORY-NAME',
     GITHUB_WORKFLOW: 'MY-WORKFLOW-ID',
     GITHUB_ACTION: 'MY-ACTION-NAME',
-    GITHUB_ACTOR: 'MY-USERNAME',
+    GITHUB_ACTOR: 'MY-USERNAME[bot]',
     GITHUB_REF: 'MY-BRANCH',
     GITHUB_SHA: 'MY-COMMIT-ID',
 };
+const GITHUB_ACTOR_SANITIZED = 'MY-USERNAME*bot*'
 
 function mockGetInput(requestResponse) {
     return function (name, options) { // eslint-disable-line no-unused-vars
@@ -208,7 +209,7 @@ describe('Configure AWS Credentials', () => {
                 {Key: 'Repository', Value: ENVIRONMENT_VARIABLE_OVERRIDES.GITHUB_REPOSITORY},
                 {Key: 'Workflow', Value: ENVIRONMENT_VARIABLE_OVERRIDES.GITHUB_WORKFLOW},
                 {Key: 'Action', Value: ENVIRONMENT_VARIABLE_OVERRIDES.GITHUB_ACTION},
-                {Key: 'Actor', Value: ENVIRONMENT_VARIABLE_OVERRIDES.GITHUB_ACTOR},
+                {Key: 'Actor', Value: GITHUB_ACTOR_SANITIZED},
                 {Key: 'Branch', Value: ENVIRONMENT_VARIABLE_OVERRIDES.GITHUB_REF},
                 {Key: 'Commit', Value: ENVIRONMENT_VARIABLE_OVERRIDES.GITHUB_SHA},
             ]
@@ -230,7 +231,33 @@ describe('Configure AWS Credentials', () => {
                 {Key: 'Repository', Value: ENVIRONMENT_VARIABLE_OVERRIDES.GITHUB_REPOSITORY},
                 {Key: 'Workflow', Value: ENVIRONMENT_VARIABLE_OVERRIDES.GITHUB_WORKFLOW},
                 {Key: 'Action', Value: ENVIRONMENT_VARIABLE_OVERRIDES.GITHUB_ACTION},
-                {Key: 'Actor', Value: ENVIRONMENT_VARIABLE_OVERRIDES.GITHUB_ACTOR},
+                {Key: 'Actor', Value: GITHUB_ACTOR_SANITIZED},
+                {Key: 'Branch', Value: ENVIRONMENT_VARIABLE_OVERRIDES.GITHUB_REF},
+                {Key: 'Commit', Value: ENVIRONMENT_VARIABLE_OVERRIDES.GITHUB_SHA},
+            ]
+        })
+    });
+
+    test('workflow name sanitized in role assumption tags', async () => {
+        core.getInput = jest
+            .fn()
+            .mockImplementation(mockGetInput(ASSUME_ROLE_INPUTS));
+        
+        process.env = {...process.env, GITHUB_WORKFLOW: 'Workflow!"#$%&\'()*+, -./:;<=>?@[]^_`{|}~🙂💥🍌1yFvMOeD3ZHYsHrGjCceOboMYzBPo0CRNFdcsVRG6UgR3A912a8KfcBtEVvkAS7kRBq80umGff8mux5IN1y55HQWPNBNyaruuVr4islFXte4FDQZexGJRUSMyHQpxJ8OmZnET84oDmbvmIjgxI6IBrdihX9PHMapT4gQvRYnLqNiKb18rEMWDNoZRy51UPX5sWK2GKPipgKSO9kqLckZai9D2AN2RlWCxtMqChNtxuxjqeqhoQZo0oaq39sjcRZgAAAAAAA'};
+
+        const sanitizedWorkflowName = 'Workflow**********+, -./:;<=>?@***_********1yFvMOeD3ZHYsHrGjCceOboMYzBPo0CRNFdcsVRG6UgR3A912a8KfcBtEVvkAS7kRBq80umGff8mux5IN1y55HQWPNBNyaruuVr4islFXte4FDQZexGJRUSMyHQpxJ8OmZnET84oDmbvmIjgxI6IBrdihX9PHMapT4gQvRYnLqNiKb18rEMWDNoZRy51UPX5sWK2GKPipgKSO9kqLckZa'
+
+        await run();
+        expect(mockStsAssumeRole).toHaveBeenCalledWith({
+            RoleArn: ROLE_NAME,
+            RoleSessionName: 'GitHubActions',
+            DurationSeconds: 6 * 3600,
+            Tags: [
+                {Key: 'GitHub', Value: 'Actions'},
+                {Key: 'Repository', Value: ENVIRONMENT_VARIABLE_OVERRIDES.GITHUB_REPOSITORY},
+                {Key: 'Workflow', Value: sanitizedWorkflowName},
+                {Key: 'Action', Value: ENVIRONMENT_VARIABLE_OVERRIDES.GITHUB_ACTION},
+                {Key: 'Actor', Value: GITHUB_ACTOR_SANITIZED},
                 {Key: 'Branch', Value: ENVIRONMENT_VARIABLE_OVERRIDES.GITHUB_REF},
                 {Key: 'Commit', Value: ENVIRONMENT_VARIABLE_OVERRIDES.GITHUB_SHA},
             ]