Re-review findings on the C3/C4 hardening branch:
- --stdio is the SSH transport whose remote argv is composed by the client
(including via --remote-option), so accepting --allow-super there let a
client defeat the C3 secure default for a root receiver. Reject it at CLI
parse time (standalone TCP only) and force the process-global flag off for
--stdio as defense in depth. Correct the help text and README/RSYNC_COMPAT:
the --stdio argv is client-composed, super stays off, and a forced command is
needed if the default must hold.
- daemon_conf: the per-module 'hosts allow'/'hosts deny' call sites passed
module_name and replace in the wrong order, so multiple lines replaced
instead of appended and the empty-value error omitted the module name. Pass
(module->name, false) like the global keys; add a unit test for two
per-module allow/deny lines appending.
- tls: read the client CN via ASN1_STRING_to_UTF8 so an exactly-required-length
name is accepted and only actual over-length CNs are rejected.