Encryption key storage error when deleting user

[PVince81]

Steps

1. Enable encryption
2. Create a user "user1"
3. Login as "user1"
4. Login as admin
5. Delete "user1"
6. Check logs

Expected result

No errors in log, user's keys properly deleted.

Actual result

Errors in log, user's key properly deleted indirectly through the deletion of the home.

{"reqId":"EL6Pp2BhEzJkzopeZJCW","remoteAddr":"127.0.0.1","app":"files","message":" Backends provided no user object for user0","level":3,"time":"2017-01-13T09:18:58+00:00","method":"DELETE","url":"\/owncloud\/index.php\/settings\/users\/users\/user0","user":"admin"}
{"reqId":"EL6Pp2BhEzJkzopeZJCW","remoteAddr":"127.0.0.1","app":"no app in context","message":"Exception: {\"Exception\":\"OC\\\\User\\\\NoUserException\",\"Message\":\"Backends provided no user object for user0\",\"Code\":0,\"Trace\":\"#0 \\\/srv\\\/www\\\/htdocs\\\/owncloud\\\/lib\\\/private\\\/Encryption\\\/Keys\\\/Storage.php(349): OC\\\\Files\\\\Filesystem::initMountPoints('user0')\\n#1 \\\/srv\\\/www\\\/htdocs\\\/owncloud\\\/lib\\\/private\\\/Encryption\\\/Keys\\\/Storage.php(182): OC\\\\Encryption\\\\Keys\\\\Storage->setupUserMounts('user0')\\n#2 \\\/srv\\\/www\\\/htdocs\\\/owncloud\\\/lib\\\/private\\\/Encryption\\\/Keys\\\/Storage.php(141): OC\\\\Encryption\\\\Keys\\\\Storage->constructUserKeyPath('OC_DEFAULT_MODU...', 'publicKey', 'user0')\\n#3 \\\/srv\\\/www\\\/htdocs\\\/owncloud\\\/apps\\\/encryption\\\/lib\\\/KeyManager.php(586): OC\\\\Encryption\\\\Keys\\\\Storage->deleteUserKey('user0', 'publicKey', 'OC_DEFAULT_MODU...')\\n#4 \\\/srv\\\/www\\\/htdocs\\\/owncloud\\\/apps\\\/encryption\\\/lib\\\/Hooks\\\/UserHooks.php(200): OCA\\\\Encryption\\\\KeyManager->deletePublicKey('user0')\\n#5 [internal function]: OCA\\\\Encryption\\\\Hooks\\\\UserHooks->postDeleteUser(Array)\\n#6 \\\/srv\\\/www\\\/htdocs\\\/owncloud\\\/lib\\\/private\\\/legacy\\\/hook.php(105): call_user_func(Array, Array)\\n#7 \\\/srv\\\/www\\\/htdocs\\\/owncloud\\\/lib\\\/private\\\/Server.php(265): OC_Hook::emit('OC_User', 'post_deleteUser', Array)\\n#8 [internal function]: OC\\\\Server->OC\\\\{closure}(Object(OC\\\\User\\\\User))\\n#9 \\\/srv\\\/www\\\/htdocs\\\/owncloud\\\/lib\\\/private\\\/Hooks\\\/EmitterTrait.php(98): call_user_func_array(Object(Closure), Array)\\n#10 \\\/srv\\\/www\\\/htdocs\\\/owncloud\\\/lib\\\/private\\\/Hooks\\\/PublicEmitter.php(32): OC\\\\Hooks\\\\BasicEmitter->emit('\\\\\\\\OC\\\\\\\\User', 'postDelete', Array)\\n#11 \\\/srv\\\/www\\\/htdocs\\\/owncloud\\\/lib\\\/private\\\/User\\\/User.php(229): OC\\\\Hooks\\\\PublicEmitter->emit('\\\\\\\\OC\\\\\\\\User', 'postDelete', Array)\\n#12 \\\/srv\\\/www\\\/htdocs\\\/owncloud\\\/settings\\\/Controller\\\/UsersController.php(467): OC\\\\User\\\\User->delete()\\n#13 [internal function]: OC\\\\Settings\\\\Controller\\\\UsersController->destroy('user0')\\n#14 \\\/srv\\\/www\\\/htdocs\\\/owncloud\\\/lib\\\/private\\\/AppFramework\\\/Http\\\/Dispatcher.php(159): call_user_func_array(Array, Array)\\n#15 \\\/srv\\\/www\\\/htdocs\\\/owncloud\\\/lib\\\/private\\\/AppFramework\\\/Http\\\/Dispatcher.php(89): OC\\\\AppFramework\\\\Http\\\\Dispatcher->executeController(Object(OC\\\\Settings\\\\Controller\\\\UsersController), 'destroy')\\n#16 \\\/srv\\\/www\\\/htdocs\\\/owncloud\\\/lib\\\/private\\\/AppFramework\\\/App.php(99): OC\\\\AppFramework\\\\Http\\\\Dispatcher->dispatch(Object(OC\\\\Settings\\\\Controller\\\\UsersController), 'destroy')\\n#17 \\\/srv\\\/www\\\/htdocs\\\/owncloud\\\/lib\\\/private\\\/AppFramework\\\/Routing\\\/RouteActionHandler.php(46): OC\\\\AppFramework\\\\App::main('UsersController', 'destroy', Object(OC\\\\AppFramework\\\\DependencyInjection\\\\DIContainer), Array)\\n#18 [internal function]: OC\\\\AppFramework\\\\Routing\\\\RouteActionHandler->__invoke(Array)\\n#19 \\\/srv\\\/www\\\/htdocs\\\/owncloud\\\/lib\\\/private\\\/Route\\\/Router.php(299): call_user_func(Object(OC\\\\AppFramework\\\\Routing\\\\RouteActionHandler), Array)\\n#20 \\\/srv\\\/www\\\/htdocs\\\/owncloud\\\/lib\\\/base.php(894): OC\\\\Route\\\\Router->match('\\\/settings\\\/users...')\\n#21 \\\/srv\\\/www\\\/htdocs\\\/owncloud\\\/index.php(46): OC::handleRequest()\\n#22 {main}\",\"File\":\"\\\/srv\\\/www\\\/htdocs\\\/owncloud\\\/lib\\\/private\\\/Files\\\/Filesystem.php\",\"Line\":413}","level":3,"time":"2017-01-13T09:18:58+00:00","method":"DELETE","url":"\/owncloud\/index.php\/settings\/users\/users\/user0","user":"admin"}

Same result with an alternative home.

However when using an alternative root for the keys (occ encryption:change-key-storage-root enckeys), the keys are NOT deleted properly because that exception makes it skip key deletion within the hook.

Versions

master a4883ae, likely introduced by #26917

Possible approaches

• run the key deletion code earlier, maybe in the pre delete hook
• or make it ignore the init mount point issue as the keys will be gone anyway through home folder deletion, but need to check if that will also work with alternative root for the keys

@SergioBertolinSG this is the issue you observed in #26844 (comment)

[PVince81]

Now I have the feeling that keys deletion itself is overkill in most scenarios when the keys are contained in the home folder. It only makes sense to do extra deletion when keys are stored separately.

But then why not do it in the pre delete hook then ? I see that trashbin clearing also operates there.

[PVince81]

Pfff, I just tried in OC 9.1.3 with "change-key-storage-root" and the keys are also not deleted properly. Well, actually it does delete the public key of the user but not the private key. And the file keys also remain.

Ok, so that will be a different issue: #26936.

So the goal in this issue here is to bring the behavior back to what it was before to eliminate the regression and annoying log messages.

[PVince81]

Fix for the alternate key root case here: #26937

Still need to work on the other case, maybe I'll just make it use the pre delete hook.

[PVince81]

Fix is here: #26938 (preDelete hook approach)

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