Suggested feature and contribution

[Bron Gondwana]

On Thu, Jul 18, 2019, at 19:09, Egoitz Aurrekoetxea wrote:
> Good morning,
> 
> When using delete_delayed if someone removes a big folder (that one with more than 20 subfolders anywhere below it) in mboxlist_delayed_deletemailbox() only last 20 are preserved. We think it could be a good idea to preserve all and to have a parameter for configuring it. The reason for that, is that we use delete_delayed for storing the removed content remotely with the customer hired retention period in slow disk space. Perhaps could be a good idea something like : 
> 
> In mboxlist_delayed_deletemailbox() : 
> 
> *If (!preserve_delete_delayed_folders_always)*
> *{*
>  /* keep the last 19, so the new one is the 20th */
>  for (i = 0; i < (int)existing.count - 19; i++) {
>  const char *subname = strarray_nth(&existing, i);
>  syslog(LOG_NOTICE, "too many subfolders for %s, deleting %s (%d / %d)",
>  newname, subname, i+1, (int)existing.count);
>  r = mboxlist_deletemailbox(subname, 1, userid, auth_state, NULL, 0, 1, 1,
>  keep_intermediaries);
>  if (r) goto done;
>  }
> *}*

Hmm.... yeah, OK. This is actually buggy in that case! The intended behaviour was to avoid a Denial of Service attack where you would create and delete the same mailbox name millions of times - however, the whole concept is bogus because there's nothing stopping somebody creating and deleting folder000001 through folderFFFFFF and creating the same attack.

I suggest that we just remove this whole silly check entirely, and if we want a similar level of attack protection we do something smarter like a quota for total folders+deleted folders that haven't been cleaned up yet - set it high enough that anybody hitting that is clearly doing something wrong, and require the administrator semi-manually clean up the deleted folders in order to re-allow folder creation.

Cheers,

Bron.

-- 
 brong at fastmailteam.com

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