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Preserve the request buffer across async SIG(0) processing

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For SIG(0)-signed requests, view matching is offloaded and the request
is finished asynchronously from ns_client_request_continue(), which
passes client->inner.buffer to dns_dt_send().  That buffer aliases the
network manager's receive buffer, only valid during the read callback,
so it may already be freed and reused, producing garbage dnstap frames
(e.g. the "upforwd" sig0-over-DoT test fails with UQ=0).

When the request is offloaded (ns_client_setup_view() returns
DNS_R_WAIT) and dnstap is enabled, copy the request buffer and point
client->inner.buffer at the copy so it survives the asynchronous hop;
free it in ns__client_reset_cb().  When dnstap is disabled there is no
async consumer of the buffer, so detach it from the receive buffer
instead.

Assisted-by: Claude:claude-opus-4-8
This commit is contained in:
Michal Nowak 2026-06-04 12:09:26 +00:00
parent c8e9823121
commit ddfe8a1bdc
2 changed files with 44 additions and 9 deletions
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33
lib/ns/client.c
View file

@ -1722,6 +1722,16 @@ ns__client_reset_cb(void *client0) {
client_put_tcp_buffer(client);
}
if (client->inner.reqbuf != NULL) {
isc_mem_put(client->manager->mctx, client->inner.reqbuf,
client->inner.reqbuf_size);
client->inner.reqbuf_size = 0;
}
if (client->inner.buffer != NULL) {
isc_buffer_initnull(client->inner.buffer);
}
if (client->inner.keytag != NULL) {
isc_mem_put(client->manager->mctx, client->inner.keytag,
client->inner.keytag_len);
@ -2162,6 +2172,29 @@ ns_client_request(isc_nmhandle_t *handle, isc_result_t eresult,
result = ns_client_setup_view(client, &netaddr);
if (result == DNS_R_WAIT) {
#ifdef HAVE_DNSTAP
/*
* The request is finished asynchronously, but the receive
* buffer is only valid during this callback; copy it so it
* survives the asynchronous hop for dnstap logging.
*/
isc_region_t r;
INSIST(client->inner.reqbuf == NULL);
isc_buffer_usedregion(client->inner.buffer, &r);
if (r.length != 0) {
client->inner.reqbuf =
isc_mem_get(client->manager->mctx, r.length);
client->inner.reqbuf_size = r.length;
memmove(client->inner.reqbuf, r.base, r.length);
isc_buffer_init(&client->inner.tbuffer,
client->inner.reqbuf, r.length);
isc_buffer_add(&client->inner.tbuffer, r.length);
client->inner.buffer = &client->inner.tbuffer;
}
#else
isc_buffer_initnull(client->inner.buffer);
#endif /* #ifdef HAVE_DNSTAP */
return;
}

20
lib/ns/include/ns/client.h
View file

@ -184,15 +184,17 @@ struct ns_client {
int16_t ednsversion; /* -1 noedns */
uint16_t additionaldepth;
void (*cleanup)(ns_client_t *);
isc_time_t requesttime;
isc_stdtime_t now;
isc_time_t tnow;
dns_name_t signername; /*%< [T]SIG key name */
dns_name_t *signer; /*%< NULL if not valid sig */
isc_result_t sigresult;
isc_result_t viewmatchresult;
isc_buffer_t *buffer;
isc_buffer_t tbuffer;
isc_time_t requesttime;
isc_stdtime_t now;
isc_time_t tnow;
dns_name_t signername; /*%< [T]SIG key name */
dns_name_t *signer; /*%< NULL if not valid sig */
isc_result_t sigresult;
isc_result_t viewmatchresult;
isc_buffer_t *buffer;
isc_buffer_t tbuffer;
unsigned char *reqbuf; /*%< request copy for async path */
size_t reqbuf_size;
dns_name_t rad; /* Zone rad domain */