prosody
94de6b7596cc
plugins/mod_tombstones.lua

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plugins/mod_tombstones.lua @ 12115:94de6b7596cc

mod_tombstones: Remember deleted accounts #1307 Presence subscriptions are normally revoked on account deletion, which informs the contact. Sometimes this notification gets lost e.g. due to s2s problems. The accounts JID may also be present e.g. in MUC affiliations, chat group member lists, pubsub subscriptions or other systems. These may grant privileges which would fall to someone who creates the same account again, which this module is meant to prevent.
author Kim Alvefur <zash@zash.se>
date Thu, 23 Dec 2021 14:08:20 +0100
child 12117:0c9b64178eda
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12115
94de6b7596cc mod_tombstones: Remember deleted accounts #1307
Kim Alvefur <zash@zash.se>
parents:
diff changeset
1 -- TODO warn when trying to create an user before the tombstone expires
94de6b7596cc mod_tombstones: Remember deleted accounts #1307
Kim Alvefur <zash@zash.se>
parents:
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2 -- e.g. via telnet or other admin interface
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Kim Alvefur <zash@zash.se>
parents:
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3 local datetime = require "util.datetime";
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Kim Alvefur <zash@zash.se>
parents:
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4 local errors = require "util.error";
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Kim Alvefur <zash@zash.se>
parents:
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5 local jid_split = require"util.jid".split;
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Kim Alvefur <zash@zash.se>
parents:
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6 local st = require "util.stanza";
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Kim Alvefur <zash@zash.se>
parents:
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7
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Kim Alvefur <zash@zash.se>
parents:
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8 -- Using a map store as key-value store so that removal of all user data
94de6b7596cc mod_tombstones: Remember deleted accounts #1307
Kim Alvefur <zash@zash.se>
parents:
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9 -- does not also remove the tombstone, which would defeat the point
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Kim Alvefur <zash@zash.se>
parents:
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10 local graveyard = module:open_store(nil, "map");
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Kim Alvefur <zash@zash.se>
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11
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Kim Alvefur <zash@zash.se>
parents:
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12 local ttl = module:get_option_number("user_tombstone_expiry", nil);
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Kim Alvefur <zash@zash.se>
parents:
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13 -- Keep tombstones forever by default
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Kim Alvefur <zash@zash.se>
parents:
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14 --
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Kim Alvefur <zash@zash.se>
parents:
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15 -- Rationale:
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Kim Alvefur <zash@zash.se>
parents:
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16 -- There is no way to be completely sure when remote services have
94de6b7596cc mod_tombstones: Remember deleted accounts #1307
Kim Alvefur <zash@zash.se>
parents:
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17 -- forgotten and revoked all memberships.
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Kim Alvefur <zash@zash.se>
parents:
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18
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Kim Alvefur <zash@zash.se>
parents:
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19 module:hook_global("user-deleted", function(event)
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Kim Alvefur <zash@zash.se>
parents:
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20 if event.host == module.host then
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Kim Alvefur <zash@zash.se>
parents:
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21 local ok, err = graveyard:set(nil, event.username, os.time());
94de6b7596cc mod_tombstones: Remember deleted accounts #1307
Kim Alvefur <zash@zash.se>
parents:
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22 if not ok then module:log("error", "Could store tombstone for %s: %s", event.username, err); end
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Kim Alvefur <zash@zash.se>
parents:
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23 end
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Kim Alvefur <zash@zash.se>
parents:
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24 end);
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Kim Alvefur <zash@zash.se>
parents:
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25
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Kim Alvefur <zash@zash.se>
parents:
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26 -- Public API
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Kim Alvefur <zash@zash.se>
parents:
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27 function has_tombstone(username)
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Kim Alvefur <zash@zash.se>
parents:
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28 local tombstone, err = graveyard:get(nil, username);
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Kim Alvefur <zash@zash.se>
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29
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Kim Alvefur <zash@zash.se>
parents:
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30 if err or not tombstone then return tombstone, err; end
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Kim Alvefur <zash@zash.se>
parents:
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31
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Kim Alvefur <zash@zash.se>
parents:
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32 if ttl and tombstone + ttl < os.time() then
94de6b7596cc mod_tombstones: Remember deleted accounts #1307
Kim Alvefur <zash@zash.se>
parents:
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33 module:log("debug", "Tombstone for %s created at %s has expired", username, datetime.datetime(tombstone));
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Kim Alvefur <zash@zash.se>
parents:
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34 graveyard:set(nil, username, nil);
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Kim Alvefur <zash@zash.se>
parents:
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35 return nil;
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Kim Alvefur <zash@zash.se>
parents:
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36 end
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Kim Alvefur <zash@zash.se>
parents:
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37 return tombstone;
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Kim Alvefur <zash@zash.se>
parents:
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38 end
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Kim Alvefur <zash@zash.se>
parents:
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39
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Kim Alvefur <zash@zash.se>
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40 module:hook("user-registering", function(event)
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Kim Alvefur <zash@zash.se>
parents:
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41 local tombstone, err = has_tombstone(event.username);
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Kim Alvefur <zash@zash.se>
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42
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Kim Alvefur <zash@zash.se>
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43 if err then
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Kim Alvefur <zash@zash.se>
parents:
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44 event.allowed, event.error = errors.coerce(false, err);
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Kim Alvefur <zash@zash.se>
parents:
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45 return true;
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Kim Alvefur <zash@zash.se>
parents:
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46 elseif not tombstone then
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Kim Alvefur <zash@zash.se>
parents:
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47 -- Feel free
94de6b7596cc mod_tombstones: Remember deleted accounts #1307
Kim Alvefur <zash@zash.se>
parents:
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48 return;
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Kim Alvefur <zash@zash.se>
parents:
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49 end
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Kim Alvefur <zash@zash.se>
parents:
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50
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Kim Alvefur <zash@zash.se>
parents:
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51 module:log("debug", "Tombstone for %s created at %s", event.username, datetime.datetime(tombstone));
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Kim Alvefur <zash@zash.se>
parents:
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52 event.allowed = false;
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Kim Alvefur <zash@zash.se>
parents:
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53 return true;
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Kim Alvefur <zash@zash.se>
parents:
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54 end);
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Kim Alvefur <zash@zash.se>
parents:
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55
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Kim Alvefur <zash@zash.se>
parents:
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56 module:hook("presence/bare", function(event)
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Kim Alvefur <zash@zash.se>
parents:
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57 local origin, presence = event.origin, event.stanza;
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Kim Alvefur <zash@zash.se>
parents:
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58
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Kim Alvefur <zash@zash.se>
parents:
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59 -- We want to undo any left-over presence subscriptions and notify the former
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Kim Alvefur <zash@zash.se>
parents:
diff changeset
60 -- contact that they're gone.
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Kim Alvefur <zash@zash.se>
parents:
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61 --
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Kim Alvefur <zash@zash.se>
parents:
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62 -- FIXME This leaks that the user once existed. Hard to avoid without keeping
94de6b7596cc mod_tombstones: Remember deleted accounts #1307
Kim Alvefur <zash@zash.se>
parents:
diff changeset
63 -- the contact list in some form, which we don't want to do for privacy
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Kim Alvefur <zash@zash.se>
parents:
diff changeset
64 -- reasons. Bloom filter perhaps?
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Kim Alvefur <zash@zash.se>
parents:
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65 if has_tombstone(jid_split(presence.attr.to)) then
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Kim Alvefur <zash@zash.se>
parents:
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66 if presence.attr.type == "probe" then
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Kim Alvefur <zash@zash.se>
parents:
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67 origin.send(st.error_reply(presence, "cancel", "gone", "User deleted"));
94de6b7596cc mod_tombstones: Remember deleted accounts #1307
Kim Alvefur <zash@zash.se>
parents:
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68 origin.send(st.presence({ type = "unsubscribed"; to = presence.attr.from; from = presence.attr.to }));
94de6b7596cc mod_tombstones: Remember deleted accounts #1307
Kim Alvefur <zash@zash.se>
parents:
diff changeset
69 elseif presence.attr.type == nil or presence.attr.type == "unavailable" then
94de6b7596cc mod_tombstones: Remember deleted accounts #1307
Kim Alvefur <zash@zash.se>
parents:
diff changeset
70 origin.send(st.error_reply(presence, "cancel", "gone", "User deleted"));
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Kim Alvefur <zash@zash.se>
parents:
diff changeset
71 origin.send(st.presence({ type = "unsubscribe"; to = presence.attr.from; from = presence.attr.to }));
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Kim Alvefur <zash@zash.se>
parents:
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72 end
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Kim Alvefur <zash@zash.se>
parents:
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73 return true;
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Kim Alvefur <zash@zash.se>
parents:
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74 end
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Kim Alvefur <zash@zash.se>
parents:
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75 end, 1);