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fix(xmpp): verify 'by' attribute of stanza-id and MAM result

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Implement security checks to ensure the 'archive_id' (XEP-0359) used
for database deduplication originates from a trusted source.

XEP-0359 Section 3.1: "The 'by' attribute MUST be the XMPP
address (JID) of the entity assigning the unique and stable stanza ID."
Furthermore, Section 4 (Security Considerations) specifies: "A client
SHOULD only trust <stanza-id/> elements from its own server or from
a MUC service it is joined to."

XEP-0313 Section 4.1.2: "The 'by' attribute of the <result/> element is
the JID of the archive being queried." and "If the 'by' attribute is not
present, the recipient MUST assume that the results are from their own
personal archive."

Let _handle_chat verify <stanza-id/> 'by' attribute matches our bare JID.
Let _handle_groupchat verify <stanza-id/> 'by' attribute matches the MUC
s bare JID.
Let _handle_mam verify the <result/> 'by' attribute matches the outer
message 'from' (archive JID). If 'by' is missing then 'from' matches our
own bare JID (personal archive).

Signed-off-by: Michael Vetter <jubalh@iodoru.org>
This commit is contained in:
Michael Vetter
2026-03-27 23:57:59 +01:00
parent 64fcdfaa0f
commit 247c44be30
1 changed files with 26 additions and 6 deletions
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32
src/xmpp/message.c
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@@ -1067,9 +1067,12 @@ _handle_groupchat(xmpp_stanza_t* const stanza)
char* stanzaid = NULL;
xmpp_stanza_t* stanzaidst = xmpp_stanza_get_child_by_name_and_ns(stanza, STANZA_NAME_STANZA_ID, STANZA_NS_STABLE_ID);
if (stanzaidst) {
stanzaid = (char*)xmpp_stanza_get_attribute(stanzaidst, STANZA_ATTR_ID);
if (stanzaid) {
message->stanzaid = strdup(stanzaid);
const char* by = xmpp_stanza_get_attribute(stanzaidst, "by");
if (by && (g_strcmp0(by, from_jid->barejid) == 0)) {
stanzaid = (char*)xmpp_stanza_get_attribute(stanzaidst, STANZA_ATTR_ID);
if (stanzaid) {
message->stanzaid = strdup(stanzaid);
}
}
}
@@ -1389,9 +1392,12 @@ _handle_chat(xmpp_stanza_t* const stanza, gboolean is_mam, gboolean is_carbon, c
char* stanzaid = NULL;
xmpp_stanza_t* stanzaidst = xmpp_stanza_get_child_by_name_and_ns(stanza, STANZA_NAME_STANZA_ID, STANZA_NS_STABLE_ID);
if (stanzaidst) {
stanzaid = (char*)xmpp_stanza_get_attribute(stanzaidst, STANZA_ATTR_ID);
if (stanzaid) {
message->stanzaid = strdup(stanzaid);
const char* by = xmpp_stanza_get_attribute(stanzaidst, "by");
if (by && equals_our_barejid(by)) {
stanzaid = (char*)xmpp_stanza_get_attribute(stanzaidst, STANZA_ATTR_ID);
if (stanzaid) {
message->stanzaid = strdup(stanzaid);
}
}
}
}
@@ -1524,6 +1530,20 @@ _handle_mam(xmpp_stanza_t* const stanza)
// <result xmlns='urn:xmpp:mam:2' queryid='f27' id='5d398-28273-f7382'>
// same as <stanza-id> from XEP-0359 for live messages
const char* by = xmpp_stanza_get_attribute(result, "by");
const char* from = xmpp_stanza_get_from(stanza);
if (by) {
if (g_strcmp0(by, from) != 0) {
log_warning("MAM result 'by' attribute (%s) does not match 'from' (%s)", by, from);
return TRUE;
}
} else {
if (from && !equals_our_barejid(from)) {
log_warning("MAM result from %s with no 'by' attribute (expected our own JID)", from);
return TRUE;
}
}
const char* result_id = xmpp_stanza_get_id(result);
GDateTime* timestamp = stanza_get_delay_from(forwarded, NULL);