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Merge "Additional documentation about Autofill / WebView security." into oc-dev am: 36cbdef880

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am: a3c2cee055

Change-Id: Ie107dd462a47009a34ee3768183dfda2e36107c3
This commit is contained in:
Felipe Leme
2017-08-15 21:48:32 +00:00
committed by android-build-merger
parent 77f3300f48 a3c2cee055
commit 2220049d58
2 changed files with 83 additions and 1 deletions
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72
core/java/android/service/autofill/AutofillService.java
View File

@@ -280,6 +280,76 @@ import com.android.internal.os.SomeArgs;
* calling {@link FillResponse.Builder#setIgnoredIds(AutofillId...)} so the system does not trigger
* a new {@link #onFillRequest(FillRequest, CancellationSignal, FillCallback)} when these views are
* focused.
*
* <h3>Web security</h3>
*
* <p>When handling autofill requests that represent web pages (typically
* view structures whose root's {@link android.app.assist.AssistStructure.ViewNode#getClassName()}
* is a {@link android.webkit.WebView}), the service should take the following steps to verify if
* the structure can be autofilled with the data associated with the app requesting it:
*
* <ol>
* <li>Use the {@link android.app.assist.AssistStructure.ViewNode#getWebDomain()} to get the
* source of the document.
* <li>Get the canonical domain using the
* <a href="https://publicsuffix.org/>Public Suffix List</a> (see example below).
* <li>Use <a href="https://developers.google.com/digital-asset-links/">Digital Asset Links</a>
* to obtain the package name and certificate fingerprint of the package corresponding to
* the canonical domain.
* <li>Make sure the certificate fingerprint matches the value returned by Package Manager
* (see "Package verification" section above).
* </ol>
*
* <p>Here's an example on how to get the canonical domain using
* <a href="https://github.com/google/guava">Guava</a>:
*
* <pre class="prettyprint">
* private static String getCanonicalDomain(String domain) {
* InternetDomainName idn = InternetDomainName.from(domain);
* while (!idn.isTopPrivateDomain() && idn != null) {
* idn = idn.parent();
* }
* return idn == null ? null : idn.toString();
* }
* </pre>
*
* <p>If the association between the web domain and app package cannot be verified through the steps
* above, the service can still autofill the app, but it should warn the user about the potential
* data leakage first, and askfor the user to confirm. For example, the service could:
*
* <ol>
* <li>Create a dataset that requires
* {@link Dataset.Builder#setAuthentication(android.content.IntentSender) authentication} to
* unlock.
* <li>Include the web domain in the custom presentation for the
* {@link Dataset.Builder#setValue(AutofillId, AutofillValue, android.widget.RemoteViews)
* dataset value}.
* <li>When the user select that dataset, show a disclaimer dialog explaining that the app is
* requesting credentials for a web domain, but the service could not verify if the app owns
* that domain. If the user agrees, then the service can unlock the dataset.
* <li>Similarly, when adding a {@link SaveInfo} object for the request, the service should
* include the above disclaimer in the {@link SaveInfo.Builder#setDescription(CharSequence)}.
* </ol>
*
* <p>This same procedure could also be used when the autofillable data is contained inside an
* {@code IFRAME}, in which case the WebView generates a new autofill context when a node inside
* the {@code IFRAME} is focused, which the root node containing the {@code IFRAME}'s {@code src}
* attribute on {@link android.app.assist.AssistStructure.ViewNode#getWebDomain()}. A typical and
* legitimate use case for this scenario is a financial app that allows the user
* to login on different bank accounts. For example, a financial app {@code my_financial_app} could
* use a WebView that loads contents from {@code banklogin.my_financial_app.com}, which contains an
* {@code IFRAME} node whose {@code src} attribute is {@code login.some_bank.com}. When fulfilling
* that request, the service could add an
* {@link Dataset.Builder#setAuthentication(android.content.IntentSender) authenticated dataset}
* whose presentation displays "Username for some_bank.com" and
* "Password for some_bank.com". Then when the user taps one of these options, the service
* shows the disclaimer dialog explaining that selecting that option would release the
* {@code login.some_bank.com} credentials to the {@code my_financial_app}; if the user agrees,
* then the service returns an unlocked dataset with the {@code some_bank.com} credentials.
*
* <p><b>Note:</b> The autofill service could also whitelist well-known browser apps and skip the
* verifications above, as long as the service can verify the authenticity of the browser app by
* checking its signing certificate.
*/
public abstract class AutofillService extends Service {
private static final String TAG = "AutofillService";
@@ -424,7 +494,7 @@ public abstract class AutofillService extends Service {
* {@link SaveCallback#onSuccess()} or {@link SaveCallback#onFailure(CharSequence)})
* to notify the result of the request.
*
* <p><b>NOTE: </b>to retrieve the actual value of the field, the service should call
* <p><b>Note:</b> To retrieve the actual value of the field, the service should call
* {@link android.app.assist.AssistStructure.ViewNode#getAutofillValue()}; if it calls
* {@link android.app.assist.AssistStructure.ViewNode#getText()} or other methods, there is no
* guarantee such method will return the most recent value of the field.

12
core/java/android/webkit/WebView.java
View File

@@ -2725,6 +2725,18 @@ public class WebView extends AbsoluteLayout
* understood by the {@link android.service.autofill.AutofillService} implementations:
*
* <ol>
* <li>Only the HTML nodes inside a {@code FORM} are generated.
* <li>The source of the HTML is set using {@link ViewStructure#setWebDomain(String)} in the
* node representing the WebView.
* <li>If a web page has multiple {@code FORM}s, only the data for the current form is
* represented&mdash;if the user taps a field from another form, then the current autofill
* context is canceled (by calling {@link android.view.autofill.AutofillManager#cancel()} and
* a new context is created for that {@code FORM}.
* <li>Similarly, if the page has {@code IFRAME} nodes, they are not initially represented in
* the view structure until the user taps a field from a {@code FORM} inside the
* {@code IFRAME}, in which case it would be treated the same way as multiple forms described
* above, except that the {@link ViewStructure#setWebDomain(String) web domain} of the
* {@code FORM} contains the {@code src} attribute from the {@code IFRAME} node.
* <li>If the Android SDK provides a similar View, then should be set with the
* fully-qualified class name of such view.
* <li>The W3C autofill field ({@code autocomplete} tag attribute) maps to