Date:   Sat Jun 15 11:27:17 2019 -0700

    [security] Match ${aws:username} exactly instead of prefix match (#7791)

    This PR fixes a security issue where an IAM user based
    on his policy is granted more privileges than restricted
    by the users IAM policy.

    This is due to an issue of prefix based Matcher() function
    which was incorrectly matching prefix based on resource
    prefixes instead of exact match.
```

	Remove(ctx context.Context, object string, rv remoteVersionID) error
	InUse(ctx context.Context) (bool, error)
}

const probeObject = "probeobject"

// checkWarmBackend checks if tier config credentials have sufficient privileges
// to perform all operations defined in the WarmBackend interface.
func checkWarmBackend(ctx context.Context, w WarmBackend) error {
	remoteVersionID, err := w.Put(ctx, probeObject, strings.NewReader("MinIO"), 5)

		if parentInClaim != parentUser {
			return false
		}
	} else {
		// This is needed so a malicious user cannot
		// use a leaked session key of another user
		// to widen its privileges.
		return false
	}

	isOwnerDerived := parentUser == globalActiveCred.AccessKey

	var err error
	var svcPolicies []string
	roleArn := args.GetRoleArn()

	switch {

- find accounts whose group memberships have changed; access policies available to a credential are updated to reflect the change, i.e. they will lose any privileges associated with a group they are removed from, and gain any privileges associated with a group they are added to.

	}

	// 3.2 check that user cannot delete the bucket
	err = uClient.RemoveBucket(ctx, bucket)
	if err == nil || err.Error() != "Access Denied." {
		c.Fatalf("User was able to escalate privileges (Err=%v)!", err)
	}
}

func (s *TestSuiteIAM) TestAddServiceAccountPerms(c *check) {
	ctx, cancel := context.WithTimeout(context.Background(), testDefaultTimeout)
	defer cancel()

	// 1. Create a policy