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Merge "Clarifies how the autofill service should check for signature hashes." into oc-dev

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This commit is contained in:
Felipe Leme
2017-08-02 15:52:05 +00:00
committed by Android (Google) Code Review
parent 6829a1dace 2fb64c0b28
commit c8f0fd7076
1 changed files with 40 additions and 3 deletions
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43
core/java/android/service/autofill/AutofillService.java
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@@ -179,11 +179,18 @@ import com.android.internal.os.SomeArgs;
* should not contain fields for username, password, and credit card information. The reason for
* this rule is that a malicious app could draft a view structure where the credit card fields
* are not visible, so when the user selects a dataset from the username UI, the credit card info is
* released to the application without the user knowledge. Similar, it's recommended to always
* released to the application without the user knowledge. Similarly, it's recommended to always
* protect a dataset that contains sensitive information by requiring dataset authentication
* (see {@link Dataset.Builder#setAuthentication(android.content.IntentSender)}).
* (see {@link Dataset.Builder#setAuthentication(android.content.IntentSender)}), and to include
* info about the "primary" field of the partition in the custom presentation for "secondary"
* fields — that would prevent a malicious app from getting the "primary" fields without the
* user realizing they're being released (for example, a malicious app could have fields for a
* credit card number, verification code, and expiration date crafted in a way that just the latter
* is visible; by explicitly indicating the expiration date is related to a given credit card
* number, the service would be providing a visual clue for the users to check what would be
* released upon selecting that field).
*
* <p>When the service detects that a screen have multiple partitions, it should return a
* <p>When the service detects that a screen has multiple partitions, it should return a
* {@link FillResponse} with just the datasets for the partition that originated the request (i.e.,
* the partition that has the {@link android.app.assist.AssistStructure.ViewNode} whose
* {@link android.app.assist.AssistStructure.ViewNode#isFocused()} returns {@code true}); then if
@@ -236,6 +243,36 @@ import com.android.internal.os.SomeArgs;
* <p>When the service returns multiple {@link FillResponse}, the last one overrides the previous;
* that's why the {@link SaveInfo} in the 2nd request above has the info for both partitions.
*
* <h3>Package verification</h3>
*
* <p>When autofilling app-specific data (like username and password), the service must verify
* the authenticity of the request by obtaining all signing certificates of the app being
* autofilled, and only fulfilling the request when they match the values that were
* obtained when the data was first saved &mdash; such verification is necessary to avoid phishing
* attempts by apps that were sideloaded in the device with the same package name of another app.
* Here's an example on how to achieve that by hashing the signing certificates:
*
* <pre class="prettyprint">
* private String getCertificatesHash(String packageName) throws Exception {
* PackageManager pm = mContext.getPackageManager();
* PackageInfo info = pm.getPackageInfo(packageName, PackageManager.GET_SIGNATURES);
* ArrayList<String> hashes = new ArrayList<>(info.signatures.length);
* for (Signature sig : info.signatures) {
* byte[] cert = sig.toByteArray();
* MessageDigest md = MessageDigest.getInstance("SHA-256");
* md.update(cert);
* hashes.add(toHexString(md.digest()));
* }
* Collections.sort(hashes);
* StringBuilder hash = new StringBuilder();
* for (int i = 0; i < hashes.size(); i++) {
* hash.append(hashes.get(i));
* }
* return hash.toString();
* }
*
* </pre>
*
* <h3>Ignoring views</h3>
*
* <p>If the service find views that cannot be autofilled (for example, a text field representing