Every client on loopback shares the 127.0.0.1 identity, so counting them
against 'max connections per host' or the default-on auth lockout lets one
local client deny service to all the others (and makes a shared-NAT/proxy
address a natural DoS vector for remote clients). Use
utils_fd_peer_is_local (fail-closed) in the daemon gate to exempt a
provably local peer from the per-source cap and the auth lockout while
keeping the per-module and global caps. Remote peers are unchanged.
Document the shared-NAT/proxy identity limitation and the loopback
exemption in README/RSYNC_COMPAT/CHANGELOG, update the integration test to
assert the exemption, and fix the README 'auth failure delay' cap (5000,
not 60000).
The per-source host table only grew: once its fixed open-addressed table
filled, host_intern returned -1 and the per-host cap plus the shared auth
lockout silently failed open forever. Add a bounded-lifetime eviction
policy: track a per-bucket last-use time and, when no empty bucket exists,
atomically repurpose the first bucket that has no active connection and
either has an expired lockout or has been idle, resetting its counters.
Warn (rate-limited) on the genuine fail-open path.
A child SIGKILLed mid-registration could also leak a module/host count
because the parent only decremented on a REGISTERED slot. Make the slot
table the source of truth: after the SIGCHLD reap the parent recomputes
module_active[]/host_active[] from the surviving REGISTERED slots (atomics
only, async-signal-safe) so any leaked increment is erased.
Also clamp module_count to DAEMON_LIMITS_MAX_MODULES and use one helper
for the sizing/register host-tracking condition (a lockout threshold with
duration 0 is a no-op and must not intern hosts).
Add a NULL guard to protocol_release_memory_for_session so it no-ops like
the sibling session setters. Correct the Data.owner doc comment, which
implied a non-zero protocol_charge always has an owner; document that
owner may be NULL for uncharged/ownerless Data, that any such charge
falls back to the bound session, and that a charged Data must not outlive
its owning session. Note the lifetime contract on the release API too.
Extend tests/test_protocol.c to cover destroying a charged Data with no
session bound (the other half of the original bug) and to assert that
data_create/data_create_reserve start with owner == NULL and
protocol_charge == 0.
test_config_wire_golden() serializes a fully-populated Config through
config_send_wire_block() and pins the exact frame to len=633 and FNV-1a
hash 6163263374908258816, captured from the pre-X-macro implementation.
Any field reorder, resize or codec change fails the test.
test_config_wire_roundtrip_all_fields() serializes/deserializes a defaults
Config and a fully-populated Config over a socketpair and compares every
serialized field. The comparison is itself generated from
CONFIG_WIRE_FIELDS (one CONFIG_CMP_<KIND> per table entry), so a new table
entry automatically extends coverage; it cannot fall out of sync. It
normalizes the receiver's NULL/"" canonicalization, the max_alloc server
clamp and the derived use_delta/use_xattrs bits.
Wire the shared registry into the accept loop (parent claims a slot before
fork, blocks SIGCHLD across fork+pid publication, and reclaims the dead
child's slot from the SIGCHLD handler so per-module/per-source counts are
released even on SIGKILL). The connection child records the selected module
and normalized peer IP once the config frame names them: an over-cap module
or source is refused at the config gate with an audit log, and a source
that exceeded the auth-failure threshold is refused before a SCRAM
challenge (the counter is shared across children and cleared on success).
The existing global cap and host ACLs are untouched.
Add global keys `max connections per host` (default 0 = unlimited),
`auth lockout threshold` (default 10, 0 disables) and
`auth lockout duration` (default 300 s, 0 disables). Module
`max connections` now accepts 0 as unlimited. Bound the number of
[module] sections (DAEMON_CONF_MAX_MODULES) so the shared registry's
per-module counter array stays fixed-size; absent keys keep their
defaults so old configs still load.
The daemon forks one child per accepted connection, so per-module and
per-source accounting must live in state shared across the children. Add a
fixed-size registry carved from an anonymous shared mapping
(mmap(MAP_SHARED|MAP_ANONYMOUS)) created before the accept loop: a slot
lifecycle (FREE/CLAIMED/REGISTERED) with parent claim/reclaim and a
lock-free, open-addressed per-source table for the per-host occupancy and
the shared auth-failure counter. C11 atomics only; no pthread locks across
fork.
Unit tests cover slot exhaustion, the module/host caps, pid reclaim and
fork-shared visibility.
Data charged against a ProtocolSession kept only the charge amount, so
data_destroy released it from whatever session was thread-locally bound
at destroy time. Destroying a received Data on another thread, after the
session was unbound, or while a different session was bound leaked the
originating session's budget and underflowed the other's.
Add Data.owner, set it whenever protocol_receive_data_limited charges a
session, and have data_destroy release against that owner directly via
the newly-exported protocol_release_memory_for_session. Uncharged Data
(owner NULL) keeps the previous bound-session fallback.
Add a unit test proving a Data acquired on session A is released to A
even when unrelated session B is bound at destroy time.
Type Config.super_mode as SuperMode (a proper C enum) instead of a bare
int. The wire boundary still carries the mode as an int: send casts the
enum explicitly and receive reads a temporary int, validates the
AUTO..OFF range, then casts. Emitted bytes and accepted values are
unchanged. ModuleGateContext.super_mode_override keeps its -1 sentinel
as int with an explicit cast at the apply site.
Behavior preserved.
- server gate: the --allow-unauthenticated loopback allowance now requires
an actual plaintext connection (!gate_ctx->ssl), so a loopback TLS client
whose cert fails the --client-cn check is refused before any SCRAM
challenge instead of falling through the plaintext opt-in. Keep the
invalid-fd guard as belt-and-braces (unreachable after the policy check).
- test: rewrote test_wrong_client_cn_refused_before_auth_challenge to run
deterministically over 127.0.0.1 with --tls + --allow-unauthenticated and
a CA-valid wrong-CN client cert, asserting the gate refusal log and an
unchanged module tree (no skip).
- docs: --client-cn is mandatory with --tls; dummykey sidecar is secret
material; document all transient-fallback reasons; qualify
--allow-unauthenticated in README and --help so it cannot read as
permitting remote plaintext auth.
- credentials.h: drop stale restrictive-umask claim (fchmod forces exact
0600; only create/write/fsync/link/fchmod failure degrades to ephemeral).
- Make the atomic-publish temp name unpredictable by appending 16 random
hex chars to the pid, so a leftover/planted temp cannot be targeted.
- On EEXIST, unlink the stale temp and retry the O_EXCL create once
(bounded), so a crash leftover or reused pid cannot silently defeat
sidecar persistence.
- fchmod the temp fd to 0600 after creation (umask can clear owner bits)
and treat failure as a create failure, so the published sidecar is
always exactly 0600.
- Clarify comments: the sidecar requires exact 0600 while the store and
password files only reject group/other bits.
- Add a unit test that a restrictive umask still yields an exact 0600
sidecar; clean random-suffixed temps in tests.
utils_fd_peer_is_local now returns true only when getpeername SUCCEEDS and the
peer address classifies as loopback. A non-socket descriptor (pipe/socketpair)
or any getpeername error is NOT local, so the daemon auth gate fails closed
instead of treating an untestable --stdio pipe as trusted (daemon auth modules
are --daemon-only and the stdio path never loads a daemon config).
server_module_gate now requires --allow-unauthenticated for the loopback
plaintext auth path: a plaintext loopback connection without the operator
opt-in is refused at the config gate BEFORE server_auth_handshake, so no SCRAM
challenge is sent. Remote peers still require verified TLS regardless of the
flag; the handler keeps its defense-in-depth checks.
Docs state the exact policy (verified TLS with matching --client-cn, or
operator-opted-in loopback plaintext), drop the SSH/stdio auth-transport claim
(they are daemon-only), and add the loopback trust-boundary relay caveat and
the CN-only (no SAN) residual. Adds a unit-test negative for pipe/socketpair
and an integration test where a relay observes no challenge when the flag is
absent.
Address review findings on the persistent dummy-key sidecar:
- Publish atomically: write a private same-directory temp file
(<store>.dummykey.tmp.<pid>, 0600), fsync, then link(2) into place;
fsync the containing directory and drop the temp name. A concurrent
starter can no longer observe a zero/partial sidecar and fail closed.
On EEXIST adopt the winner's sidecar; otherwise warn and use a
transient ephemeral key.
- Harden the read path (initial and EEXIST-adopt) with
O_RDONLY|O_NOFOLLOW|O_NONBLOCK|O_CLOEXEC: reject planted symlinks
(ELOOP fails closed) and never block on a planted FIFO.
- Require the exact owner-only mode (st_mode & 07777) == 0600 and make
the rejection message truthful.
- Report a clear "short write" instead of a stale strerror(errno) when
write() returns 0.
- Document the artifact and its creation-failure caveat (FIFO store
path, read-only filesystem, missing directory) in README.md and
RSYNC_COMPAT.md.
- Tests: known-key sidecar adoption (dummy salt KAT + reload), symlink
rejection, and the exact-0600 rule (0400 now rejected).
Daemon modules that declare 'auth users' no longer accept credentials over a
remote plaintext connection: server_module_gate refuses at the config gate,
before any SCRAM challenge is sent, unless the connection is verified TLS with
a client certificate matching --client-cn, or a local/SSH transport (loopback
TCP peer or the --stdio pipe). --allow-unauthenticated does not relax this.
The TLS client-CN comparison now uses credentials_secure_equal (S2). Clients
sending --password-file to a non-loopback daemon must use --tls; validate_config
rejects the plaintext case before any network I/O.
Adds utils_sockaddr_is_loopback / utils_fd_peer_is_local / utils_host_is_loopback
helpers with unit tests, a client validation unit test, and integration tests
for the client-side plaintext rejection and the wrong-CN gate refusal.
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