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gdm: Limit verification cancellations to be conform to allowed-failures

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As per previous commit the user can cancel an ongoing authentication via
Escape key and that will always send the user back to the clock view in
lockscreen or user-selection view in login prompt.

However, we can be a little more permissive and don't switch view to be
able to restart the authentication without further action.

To avoid this to be abused though, we consider the user verification
cancellation via escape key to be a "soft-failure", so once the
configured "allowed-failures" gsettings value has been reached, we'd
just act as before, ignoring any further request (until we don't get
back to the user auth view).

In this way we still make brute-force attacks harder to do, while still
giving the well-behaving user some ability to fix mistakes.

Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1622>
This commit is contained in:
Marco Trevisan (Treviño) 2021-02-01 13:10:45 +01:00 committed by Marge Bot
parent 7e77881717
commit c8bb45b41c
3 changed files with 25 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

16
js/gdm/authPrompt.js
View File

@ -30,11 +30,13 @@ var AuthPromptStatus = {
VERIFICATION_FAILED: 2,
VERIFICATION_SUCCEEDED: 3,
VERIFICATION_CANCELLED: 4,
VERIFICATION_IN_PROGRESS: 5,
};
var BeginRequestType = {
PROVIDE_USERNAME: 0,
DONT_PROVIDE_USERNAME: 1,
REUSE_USERNAME: 2,
};
var AuthPrompt = GObject.registerClass({
@ -59,6 +61,7 @@ var AuthPrompt = GObject.registerClass({
this._gdmClient = gdmClient;
this._mode = mode;
this._defaultButtonWellActor = null;
this._cancelledRetries = 0;
let reauthenticationOnly;
if (this._mode == AuthPromptMode.UNLOCK_ONLY)
@ -196,6 +199,7 @@ var AuthPrompt = GObject.registerClass({
}
_activateNext(shouldSpin) {
this.verificationStatus = AuthPromptStatus.VERIFICATION_IN_PROGRESS;
this.updateSensitivity(false);
if (shouldSpin)
@ -501,6 +505,9 @@ var AuthPrompt = GObject.registerClass({
// We don't need to know the username if the user preempted the login screen
// with a smartcard or with preauthenticated oVirt credentials
beginRequestType = BeginRequestType.DONT_PROVIDE_USERNAME;
} else if (oldStatus === AuthPromptStatus.VERIFICATION_IN_PROGRESS) {
// We're going back to retry with current user
beginRequestType = BeginRequestType.REUSE_USERNAME;
} else {
// In all other cases, we should get the username up front.
beginRequestType = BeginRequestType.PROVIDE_USERNAME;
@ -549,7 +556,14 @@ var AuthPrompt = GObject.registerClass({
if (this.verificationStatus == AuthPromptStatus.VERIFICATION_SUCCEEDED)
return;
this.verificationStatus = AuthPromptStatus.VERIFICATION_CANCELLED;
if (this.verificationStatus === AuthPromptStatus.VERIFICATION_IN_PROGRESS) {
this._cancelledRetries++;
if (this._cancelledRetries > this._userVerifier.allowedFailures)
this.verificationStatus = AuthPromptStatus.VERIFICATION_FAILED;
} else {
this.verificationStatus = AuthPromptStatus.VERIFICATION_CANCELLED;
}
this.reset();
}
});

7
js/gdm/loginDialog.js
View File

@ -855,6 +855,7 @@ var LoginDialog = GObject.registerClass({
this._resetGreeterProxy();
this._sessionMenuButton.updateSensitivity(true);
const previousUser = this._user;
this._user = null;
if (this._nextSignalId) {
@ -862,7 +863,11 @@ var LoginDialog = GObject.registerClass({
this._nextSignalId = 0;
}
if (beginRequest == AuthPrompt.BeginRequestType.PROVIDE_USERNAME) {
if (previousUser && beginRequest === AuthPrompt.BeginRequestType.REUSE_USERNAME) {
this._user = previousUser;
this._authPrompt.setUser(this._user);
this._authPrompt.begin({ userName: previousUser.get_user_name() });
} else if (beginRequest === AuthPrompt.BeginRequestType.PROVIDE_USERNAME) {
if (!this._disableUserList)
this._showUserList();
else

4
js/gdm/util.js
View File

@ -192,6 +192,10 @@ var ShellUserVerifier = class {
}
}
get allowedFailures() {
return this._settings.get_int(ALLOWED_FAILURES_KEY);
}
begin(userName, hold) {
this._cancellable = new Gio.Cancellable();
this._hold = hold;