Commit Graph
14 Commits
Author SHA1 Message Date
mixandClaude Opus 5.5 0cceb549cc sender check: a Sender: line is held to the rule From: is held to
test / test (push) Waiting to run
The owner's decision (2026-10-16) on the security review's F1: a Sender:
line - the sending agent's, shown beside From: as "on behalf of", and
signed since 2.8.0 - was neither held to the login nor, before, signed: an
application could write its own From: and Sender: ceo@bank.com under this
server's signature. Now, when a message has one, it must be one address
the application may send as, and at most one such line (RFC 5322 § 3.6);
From: is judged first.

The refusal is "550 5.7.1 Sender: <address> - <why>", a send-log row of
reason "sender" (store.ReasonSender), tagged "wrong Sender"; the message
page names the line. The log tailer recovers such a row from cleanup's line
as it does a From: refusal (fromRefusalRe reads either). Help text as in
the design commit d9d9af3; guide, architecture, security and CHANGELOG say
it, security.md keeps Resent-From: (signed, not judged) as an accepted
risk.

Tests: TestSenderLineHeldToTheSameRule (own address, a name, another
application's, a stranger's, two addresses, two lines, From: first), the
recovery of a Sender: refusal line, the tag, the message page; e2e
sender_check_holds_the_sender_line (own Sender: passes and is signed,
another domain's refused at DATA and logged).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
2026-10-16 07:41:42 +03:00
mixandClaude Opus 5.5 faa3c11ae7 panel-dkim-signing stage 2: OpenDKIM removed
test / test (push) Canceled after 0s
The panel's signer is the only one. Gone: the opendkim package and its
configuration, the syslog-relay and opendkim programs, /dev/log and
/run/opendkim, the reload by USR1 through supervisord
(internal/supervisor/supervisor.go), internal/syslogrelay, the port of
OpenDKIM's From: parser (internal/milter/mailparse.go and its probe,
harness and test/upstream scripts), OPENDKIM_SOCKET and OPENDKIM_DIR.

Keys: internal/domain/keys.go (Keys, NewKeys, DKIM_DIR=/data/dkim) keeps
the keys and writes a selector table, /data/dkim/selectors ("<name>
<selector>"), which the signer reads in place of the KeyTable - it reads
no database, as the sender check reads none. The table is written before
the signer serves (EnsureServerSigned moved there from the notifier).
Keys and table 0600, directories 0700, the panel's. The entrypoint copies
/data/opendkim/keys once, as the panel user, into /data/dkim.new renamed
when whole, and stops the start if the copy fails; /data/opendkim is left
for a rollback to 2.7.x.

Sender check: one RFC 5322 address as a mail program reads it, held
against the bindings; the 256-byte refusal and the texts naming OpenDKIM
go. Allowed() folded the domain through strings.ToLower, which makes the
Kelvin sign a "k" - the comparison with OpenDKIM's reading had hidden it;
it folds ASCII only now.

Health: two dkim-signer rows (applications, notifications) in Milter
sockets, opendkim out of the liveness set; the card no longer takes any
row with a note for the spam filter. Texts as in the design commit.

KILL stays in deploy/docker-compose.yml: measured on the test server,
root without it cannot signal a process of another uid - supervisord
stopping the panel, Postfix's master its children. The plan's "only use
was the reload" was wrong; the comment now gives the real uses.

e2e: one signature, the panel's, verified by dkimpy; the /data/dkim modes;
the OpenDKIM log and process checks, testNeverSignedForAnother and the
cited opendkim, libopendkim11 and libmilter1.0.1 go.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
2026-10-16 01:05:39 +03:00
mixandClaude Opus 5.5 1c6e04b7d3 base-trixie: the image on Debian trixie, Postfix 3.10.13; Received: hidden on 465/587
test / test (push) Canceled after 0s
The runtime base is debian:trixie-slim, the build stage golang:1.26-trixie:
Postfix 3.10.13 with upstream's 2026 security fixes up to the August
batch, libmilter 8.18.1, OpenSSL 3.5. Every citation of another program in
code, scripts and documents was re-read against the trixie sources
(dev/upstream; bookworm's kept in dev/upstream-bookworm) and updated;
development.md's cited-package table holds the trixie versions.

What the re-reading changed in behaviour:
- logtail: reject lines with sasl_method/sasl_username/sasl_sender
  (smtpd_check.c:1019-1026); cleanup's "removed (canceled)" forgets a
  port-25 id (cleanup_api.c:363-364).
- internal/postfix/retry.go reads postconf's stdout only: since 3.9 a
  deprecated-parameter warning on stderr made one value too many and the
  panel fell back to the compiled-in retry policy.
- logrotate-loop.sh: logrotate 3.22 exits 1 when it ignores a config;
  the loop refuses on that output whatever the status.
- postfix-config.sh: cyrus_sasl_config_path set explicitly (bookworm's
  07_sasl_config.diff is gone); maillog_file_permissions=0640; mynetworks
  explicit; Dockerfile: SYNC_CHROOT= in /etc/default/postfix,
  opendkim-tools dropped, openssl named, systemd-standalone-sysusers so
  cron does not bring the whole of systemd.
- The selfpost group is 10998, outside the system range 100-999: in
  trixie a package took 998 and the build failed (owner's decision:
  a conflict-free id, the distribution's own ids untouched). The
  entrypoint hands /data back by name when the user or the group differs.
  Guide, backup refusal text, help (design commit 68ec8b2), e2e.
- smtpd_hide_client_session=yes on smtps and submission (owner's
  decision): Received: names no client, TLS, login or protocol; port 25
  keeps the full header. e2e checks both.
- test/upstream/opendkim-probe.sh makes keys with openssl genrsa.

Tests: on the server, make e2e exit 0 (674 s, the image built on trixie),
go vet + go test 27 packages ok. CHANGELOG [Unreleased], guide,
architecture.md, security.md, roadmap.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
2026-10-15 19:31:35 +03:00
mixandClaude Opus 5.5 6023feb405 audit 6: documents, comments, dead code and staticcheck; the test gaps closed
test / test (push) Canceled after 0s
The last stage of the 2026-10-12 audit; no cut.

Doc drift: architecture.md (the sender check in § OpenDKIM, the limit:
row's 48 hours, the inbound log and filter-list routes and who may open
them, migrations to 0011 and every table, KitPage as production data,
Reload configuration as a restore writes, the panel's roles counted),
schema-migrations.md (tables and columns since v2), guide.md (a delivery's
lines go at the next prune; INBOUND_JOURNAL_MILTER_SOCKET moved to
architecture.md's internal list), development.md (the env guard, the
deferral the e2e proves, its fixed sleeps), roadmap.md.

Comments say what the code does now; TestBaselineIsTheOnlyMigration is
TestChainStartsAtTheBaseline; the milter package doc names its three
milters.

Dead code gone: view.Facts, dmarc HostedSuggestion and
ValidateHostedAddress, app UpdateMode (each with the test that alone kept
it), the method checks the method-bound routes made dead;
Settings.WithResult calls resultFlash. staticcheck 2026.1 in test.yml on
both modules, clean: the e2e package builds without its tests now (a test
and two constants moved out of non-test files), three findings fixed.
The test moved, TestImageBuildPreservesLogrotateMode, had sat in a
non-test file and never run; run, it failed on the entrypoint (docker run
without a hostname) and now asks with --entrypoint stat.

The test gaps no step named, each closed: follow() with mail.log gone past
blindMin and made again; CheckRestore with a manifest that is not JSON;
the origin check with a port; every /server/ pattern in web.go through
server() and in the routes table (it found GET /server/health/fragment
missing from the table - guarded, not tested); L9 as the owner decided it
on 2026-10-12, the comment on senderSession.Headers and the test passing
an h that holds the earlier messages' From:.

Plan stage 6 ticked; roadmap audit row done, 81/81.

Tested on the test server: go vet + go test of 27 packages, make e2e (all
pass, 513 s) on this tree; staticcheck locally on both modules.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
2026-10-15 14:41:26 +03:00
mixandClaude Opus 5.5 9eddd49602 audit 2c: findings of the two reviews
test / test (push) Canceled after 0s
Technical review (Opus, 11 findings, 2 medium) and security review (Fable,
no high or medium) of 3c86280..HEAD. Both confirm the port gives
dkim_mail_parse()'s result on every input it parses, and that no line the
check passes is signed with another domain's key.

- F1 (medium): OpenDKIM's parser takes lines no mail program reads as one
  address - "ceo@bank.com:me@mine.com", "Name <ceo@bank.com:me@mine.com>",
  "<b@evil.com, a@mine.com>", "ceo@bank.com <me@mine.com>",
  "ceo@bank.com@mine.com" - and signs for the last while a lenient reader
  shows the first. The line must now also be one address in RFC 5322's
  grammar (net/mail, display names in any charset passed through), at the
  domain OpenDKIM signs for. A quoted display name may still hold anything.
- F2 (medium): the bindings were asked about OpenDKIM's form of the
  address, quotes and all, so "x"@mine.com passed for an application
  holding @mine.com while x@mine.com belonged to another. They are now
  asked about the reader's address, its local part unquoted, as Postfix
  holds the envelope's.
- F3 / security (low): Bindings.Allowed and DomainOf fold case in ASCII
  only: Postfix folds as Unicode (casefold.c, ICU), but every key and
  login the panel writes is ASCII, and the Unicode fold let the Kelvin sign
  pass for "k" (net/mail then refuses such a line on the domain test).
- F4 (low): a TERM between "postfix start-fg &" and "child=$!" is no longer
  lost: the wrapper stops Postfix as soon as the pid is known.
- F5 (low): for startsecs after a start any failed reload passed as "not
  running". postfix-reload is now build/postfix-reload.sh: exit 75 when
  master -t says no master runs, else exec postfix reload; RunOnce returns
  EndError with the status, and only 75 is taken as done. supervisor.State
  goes.
- F6 (low): crashexit spares postfix-reload too - a reload that could not
  be spawned is reported to whoever asked, not a reason to stop the
  container.
- F7 (low): a certs/ that is itself a link is resolved before the walk
  (filepath.WalkDir does not follow its root).
- F8 (low): at shutdown the tailer reads what is left of the rotated
  file before saving its place. Not changed: a refusal line still waiting
  on the old file at shutdown is not kept - the panel writes refused rows
  itself, only a kill loses one, and that window is the minute's grace.
- F9 (low): pct read as text - empty or unreadable is 100, the rest held
  to 0..100.
- F10 (low): the directory is synced after sasldb2's rename.
- F11 (low): POSTFIX_STARTSECS by expr, so "010" or "08" in
  MILTER_WAIT_TIMEOUT are decimal, not octal or an error.
- Security (low): pagehide also empties defaultValue - the input's value
  attribute and the textarea's text - not only .value. A sasldb2.new left
  by a killed panel is removed at start (entrypoint) and never archived.
  security.md says that links under certs/ are followed and by whom they
  can be placed.

Tests: sender check cases for F1 (four lines), F2 (a bound address
quoted, for its owner and for another), F3; EndError's state and status;
pct cases. architecture.md and CHANGELOG describe the reader rule. Stand
(2026-10-15, make e2e, exit 0); go vet and go test ./... pass on the
server (24 packages).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
2026-10-15 09:17:33 +03:00
mixandClaude Opus 5.5 3584adcbc2 sender check: From: read with OpenDKIM's own parser; L8 closed
test / test (push) Canceled after 0s
Audit 2026-10-12, stage 2c, the owner's decision of 2026-10-14: the check
decides by the address OpenDKIM signs for, whatever a display name or a
comment holds.

internal/milter/mailparse.go ports libopendkim's dkim_mail_parse() with
dkim_mail_first_special(), dkim_mail_token() and
dkim_mail_matching_paren() from Debian's opendkim 2.11.0~beta2-8+deb12u1,
line for line: the '<' form, group and list punctuation, an '@' before the
first ':', ';' or ',' deciding where the address starts, source routes
dropped, quoted strings and domain literals kept with their delimiters,
comments skipped, whitespace between atoms one space, no encoded word
decoded; and the C's own quirks ("@d" gives d as the local part too).
testdata/mailparse_harness.c compiles the C from the image's source; the
test feeds it and the port 200 019 lines (the hand-written cases and
200 000 random ones over the specials) - 93 443 parse and agree byte for
byte, 106 576 fail and agree on the error (on an error the C leaves its
in-place result unterminated, and OpenDKIM uses neither part then).

judge(): one From: field and one address stay required (moreAfter: only
list or group punctuation may follow); what OpenDKIM cannot read is
refused (mlfi_eoh() would not sign it); the address is lower-cased in
ASCII only, as dkimf_lowercase() and Postfix's tables do. Found reading
dkimf_apply_signtable(): OpenDKIM matches its refile SigningTable against
"user@domain" printed into MAXADDRESS + 1 = 257 bytes, so a longer address
is matched cut short - a quoted local part padded to end there in
"@another.tenant" would be signed with that tenant's key while its real
domain is the application's. Such an address (over 256 bytes) is refused;
one that fits is matched whole. The display-name and comment scan, the
"one @ outside quotes" rule and the SigningTable reader (Signers) go; the
check asks for header values with their leading space as OpenDKIM does
(OptHeaderLeadingSpace; Postfix keeps a v2 milter's event mask, milter8.c
milter8_negotiate()).

L8 closed: refused or passed no longer depends on other domains of the
server; security.md's accepted risk is struck. The shared other-sender
lines are now held to "never signed for the other sender": unit test (a
passed line is read at the application's domain) and e2e (a passed line
arrives signed for the application's domain, none for the other).
Documents: architecture "How the header is read", security's sender
check paragraph, the guide; the help topic per 2cf118c.

Stand (2026-10-15, make e2e, exit 0): sender_check_holds_the_from_line -
another sender's address in the display name now passes; a From: whose
quoted local part is padded so that, cut at 256 bytes, it ends in
"@other.e2e.test" is refused 550 5.7.1 "the address is longer than
OpenDKIM reads whole"; lines_naming_another_sender_never_signed_for_it
and passed_from_lines_signed_for_their_domain_only pass. go vet and go
test ./... pass on the server (24 packages); the differential test ran
there against the compiled C.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
2026-10-15 02:48:02 +03:00
mixandClaude Opus 5.5 55aef6e721 sender check: the sender map read and looked up as Postfix does it
Postfix 3.7.11 takes the owners of the first key mail_addr_find() finds -
the address, then without its extension, then @domain, each tried only
when the one before is absent (src/global/mail_addr_find.c,
mail_addr_find_opt()) - and compares the login with them by
strcasecmp_utf8() (src/smtpd/smtpd_check.c,
reject_auth_sender_login_mismatch()). The check accepted a From: address
when any of the three keys named the application: an application holding
@domain could write an address listed for another application of the
domain, which Postfix refuses it in the envelope, and have it signed
(assumptions B-PS1).

The table is now read as dict_thash_open() reads it: continuation lines,
owners split on commas and blanks (B-PS4), the key ending at the first
blank outside quotes, keys folded; a key given twice makes Postfix refuse
the whole table (no DICT_FLAG_DUP_* flag), and the check then defers too.
The writer folds keys, so two cases of one address cannot be two lines.

e2e on the stand (2026-10-14, make e2e, exit 0): the wildcard application
is refused billing@ - listed for app-list - in From: (550 5.7.1), and in
the envelope by Postfix at RCPT ("553 5.7.1 <billing@...>: Sender address
rejected: not owned by user"). go vet and go test ./... pass on the
server (23 packages).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
2026-10-14 20:03:34 +03:00
mixandClaude Opus 5.5 b113e72c71 milter, postfix, app, domain: cite the source of what they rely on (assumptions part B)
Comments only, no behaviour changed. go-milter v0.4.1 (session.go: one
session per connection, replaced after a non-continue reply; macros per
stage), Postfix 3.7.11 (milter8.c, smtpd_check.c
reject_auth_sender_login_mismatch(), mail_addr_find.c, showq_compat.c,
mail_conf_time.c, mail_params.h), Cyrus SASL 2.1.28 (saslpasswd.c,
plugins/sasldb.c: deleting a missing login is not an error), OpenDKIM
2.11.0~beta2 (opendkim-db.c, opendkim-genkey), Berkeley DB 5.3 db_dump,
rspamd 3.11.0. Comments that claimed what the source denies are corrected
(sasldb keeps the password as given, not hashed; an embedded newline is
kept, not truncated; rspamd sorts symbols by absolute weight); fixtures say
seen or composed. The sender check's From: parsing gets no citations: it is
replaced by the port of OpenDKIM's dkim_mail_parse next.

Contradictions left for their own commits: B-G5 cleanAddress, B-PS1 first
key wins, B-PQ1 the forced-expire flag, B-PQ10/PQ11 Postfix's time units.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
2026-10-14 19:36:12 +03:00
mixandClaude Opus 5.5 af130e268a findings of the reviews of audit stage 2b
Technical review (Opus) and security review (Fable) of 5be109b..5154bba;
reports in the session's scratchpad. Nothing above low from security; one
bug and three risks from the technical review. Migration 0009 is not
deployed, so it was extended.

- Bug: two refusals of one second swapped their NOQUEUE lines (each line
  went to the newest lineless row). AttachRefusalLine now matches the
  client address too (send_log.client_ip, written by the journal milter -
  Postfix's line names the client and the sender, never the login: the
  sasl_username part of the pattern never matched and could be fed by HELO,
  security F1/F2), takes the nearest row in time and the oldest of equals,
  and a line already on a row goes on no other (security F6).
- Waiting lines and recoveries lived only in memory while the saved offset
  moved past them: a stop within 30 s lost them. The tracker now never saves
  an offset past the oldest waiting item in its file (tracker.hold,
  refusalLines.oldest) - for a recovery, the client= line that names its
  login - so they are read again; the "once" guards make that harmless.
- A recovered row whose login the tailer did not see was nobody's: its
  domain_id falls back to the envelope domain's.
- The fingerprint's file identity is the inode alone: the device number can
  change across a host reboot and make the same log look rotated.
- A refused row carries its queue id; UpdateStatus's "newest row" now skips
  refused rows, so a later message with that id does not flip it to sent.
- The alive mark: its age is read first and kept from then on, so asking
  supervisord for 30 s cannot make it stale; the entrypoint removes it with
  the sockets - a container restart is not the check's downtime, and a mark
  from before would have counted the whole outage as "≈".
- Security F3: the sender check prints no ";" of the client's in the From:
  text of its reply, and the tailer reads the envelope after the first ";"
  - Postfix's own text.
- A refused row with a queue id and no stored lines says so (it was told the
  mail.log text of 2.2.0); the fact's em dash is the house hyphen.
- Docs: architecture (client address, no login), guide § Health (warns on
  either count), help topics log and sender-check (design 1ca87f2).
- e2e: refusals_show_postfixs_line wants the refusal's own sender in the
  line; refusal_recovered_from_the_log waits past the tailer's 30 s and
  checks that a refusal the panel wrote got no recovered twin.

Not changed, written down: review 9 (mail.log.1 read to its end at that
moment; postlogd may still write to it until the reload), 10 (a log under
512 bytes has no fingerprint, so places fall back to time briefly after a
rotation), 6 (a 451 at MAIL FROM of another milter reads the same - the
client and sender must match too now), security F5/F12 (info). Review 12:
the refused and closed-by-the-panel variants of out-message were shown to
the owner as pictures of the real templates, not drawn in out-message.html:
the guard ties every drawn screen to a page of the engine, and a variant
has the page's outline.

Evidence on the test server for this tree: go vet clean, go test ./... 23
packages ok, make e2e exit 0 (refusal_recovered_from_the_log 70 s).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
2026-10-14 18:38:22 +03:00
mixandClaude Opus 5.5 e166a2ebd6 refused messages: the page shows what Postfix wrote (stage 2b, 0009)
The Delivery log box of every refused row said "This message never reached
the queue, so Postfix wrote no delivery lines for it" - untrue: Postfix
wrote a line for each. The owner, 2026-10-13: the box is required on every
message page. Pictured for him first (dev/shots, the refused variant of
out-message: wrong From with its queue id lines, rate-limited with the
NOQUEUE line); the variant has no mockup screen of its own - the guard ties
screens to pages, and its outline is out-message's.

- Wrong From: cleanup gives the message a queue id before the headers are
  judged; the sender check reads {i} at end-of-headers and writes it on the
  refused row. Its lines - stored under the id like any other's - are on the
  page, but only those from 10 minutes before to 1 minute after the refusal
  (store.SendLogLines for a rejected row): Postfix frees the id at once, and
  a later message with it lends nothing. No mail.log fallback for a refused
  row, for the same reason.
- Rate-limited and wrong client: refused at MAIL FROM, no queue id. Migration
  0009 adds send_log.refusal_line; logtail.refusalLines matches smtpd's
  "NOQUEUE: milter-reject: MAIL from ...; from=<...>" (not port 25's, not
  CONNECT/EHLO) and store.AttachRefusalLine puts it on the newest refused row
  of that sender (and login, when the line names it) within two minutes; a
  line whose row is not written yet waits up to 30 s (retried at each pass).
- The page: the queue id fact says "given, the message was not queued" or
  "none - refused at MAIL FROM, before one is given"; the box's caption is
  "The line from mail.log for this refusal" for the latter; a row from
  before says the line was not kept. LogLineLevel colours a refusal by its
  reply: 5xx red, 4xx amber (IPv6 clients included). The id in the fact is
  not muted as in the picture: the kit has no muted inline.

Tests: store (attach by sender, login, time; not a queued row, not one an
hour off; a refused row's lines are its own minutes); logtail (attach, wait
and retry, port 25 and other lines ignored); milter (the refused row carries
{i}); view (facts, caption, line levels); handlers (the line on the page,
the sentence without it). e2e refusals_show_postfixs_line: a client-address
refusal made there, and the pages of a wrong From, a rate-limited and a
wrong client refusal each show Postfix's line.

schema-migrations row 9, CHANGELOG [Unreleased], audit plan line ticked,
roadmap 25/62.
Evidence on the test server for this tree: make e2e exit 0 (the new case
in 5.4 s); go test ./... ok but for two schema tests, fixed after the run
(the schema at 0009) - store tests ok locally; the full run follows before
the push.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
2026-10-14 16:56:29 +03:00
mixandClaude Opus 5.5 5747f0b25c sender check: the reply names no other domain (L8); which key signs, tested (stage 2)
L8: a From: line naming another sender of the server was refused with
"it names another sender of this server, <domain>" - a confirmation, to
whoever tries names, that the domain is hosted here. The reason now stops
before the domain; the line as written stays in the reply (the client's own
text) and on the refused message's page (header_from). Unit test: the reason
of every refusal names none of the server's other domains; e2e: the reason
of each sender-check refusal does not contain other.e2e.test.

Which key OpenDKIM signs with (owner, 2026-10-13): the check and OpenDKIM
read From: with two parsers, and their agreement was argued, never run.
internal/milter/testdata/from-lines-passed.txt holds the lines the check
passes for an application - bare and bracketed, quoted names with a comma,
escaped quotes and an address inside, an extension, three encoded charsets,
two folded lines, comments (nested too), a stranger's address in the name -
as Go-quoted strings with {domain}. The unit test wants each passed; the new
e2e case passed_from_lines_signed_for_their_domain_only sends each as app1
and wants every DKIM signature at the sink to be for the sender domain,
with one valid. All fifteen were. "(the shop) a@domain" - a comment before
the address, valid RFC 5322 - is refused by the check ("it must be one
address"); strict, not a hole, so it is not in the file. Groups are refused
too.

Audit plan lines ticked (two) with what was found, CHANGELOG [Unreleased],
roadmap 21/62.
Evidence on the test server for this tree (with a618ffb): go vet clean, go
test ./... 23 packages ok, make e2e exit 0 - the new case passed in 4 s.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
2026-10-14 15:44:57 +03:00
mixandClaude Opus 5.5 c817f0833c from-header-binding: what the reviews had left as found, and address extensions
test / test (push) Canceled after 0s
The owner on the three things the reviews' commit left as found: can they be
fixed? They can.

- Downtime that crossed a UTC midnight was all booked on the day of the
  restart: it is cut at the midnights between (byDay).
- A message with the null envelope sender - a bounce an application writes
  itself - left a refusal row without a domain, which no domain
  administrator would see: the row takes the domain the login is bound to.
- A log read again after an unclean stop counted its deferrals again: while
  the tailer catches up, a warning no later than the last one counted is
  passed over. The mark is kept to the fraction of a second the log gives.

And on the check being stricter than Postfix for an address with an
extension (invoices+x@ passed in the envelope, was refused in the header):
it makes Postfix's second try now, the address without its extension.
recipient_delimiter was the distribution's default; it is set in
postfix-config.sh, since the check depends on it. e2e sends one through.

Test server, this tree: go vet ok, go test 23 packages ok, make e2e ok (339 s).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
2026-10-12 21:29:17 +03:00
mixandClaude Opus 5.5 89fd0a6116 from-header-binding: findings of the technical and security reviews
test / test (push) Canceled after 0s
Both reviews were of c171fb5, read-only, given the code and questions.

Found by both, and the one that would have refused ordinary mail from the
first day: a folded From: line - what a mail library makes of a long display
name - did not parse and was refused with 550. The line is unfolded before it
is read. e2e sends one through Postfix now.

Technical (Opus)
- A display name in a charset Go does not convert (windows-1251, koi8-r) was
  refused: such a name is passed through unread, only the address is judged.
- The statistics ran between binding the socket and serving it, with a
  supervisorctl that has no timeout: they are kept beside the check now and
  nothing of them is waited for. A supervisorctl that fails is logged.
- The count of deferred mail followed smtpd's reject lines and so missed a
  check that stops answering in the middle of a message, where cleanup
  writes them: it is taken at Postfix's warning, the line that names the
  socket. The test line for that case had been invented with the wrong
  process; it is marked as composed from Postfix's source.
- A card whose figures could not be read showed zeros and "ok": dashes and
  "unknown".
- entrypoint removes the sockets a killed container left, which satisfied
  the wrapper's wait before the check was listening.
- Outside quoted strings the line may hold one "@" only - a rule that needs
  no knowledge of OpenDKIM's parser.
- Comments that still spoke of two sockets, or of a session replaced after a
  refusal; the limits of the cards layout on a phone, said where it is defined.

Security (Fable; no Critical or High)
- Another sender's name in an encoded display name passed the second look:
  the decoded name is looked at as well.
- A client could arm the deferred counter by sending the socket's name where
  Postfix quotes it in a warning: the two warnings are matched from their
  first word.
- A refused message wrote a row per recipient: one row, naming the first
  recipient and how many more.
- Docs: the check's lookup is stricter than Postfix's for address extensions
  and the case of logins, rather than "cannot disagree"; what a display name
  looks like to a person is not promised; the timeouts and the 454 at AUTH
  stated as they are; "messages" are connections turned away.

Left as found, in the plan: downtime that crosses midnight is booked on the
day of the restart; a message with the null envelope sender leaves a row
without a domain; a log read again after an unclean stop counts again.

Test server, this tree: go vet ok, go test 23 packages ok, make e2e ok (330 s).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
2026-10-12 20:06:02 +03:00
mixandClaude Opus 5.5 c171fb5bc7 from-header-binding: the sender check, what it costs, its pages; guide, architecture, security
test / test (push) Canceled after 0s
A message's From: line is held against the application that sends it, under
the rule Postfix holds the envelope sender to. OpenDKIM chooses the key by
that line, so until now an application could have mail signed as another
domain of the server or as the server itself.

The check (internal/milter/sender.go)
- A role of the panel on a socket of its own (SENDER_CHECK_SOCKET), first in
  smtpd_milters and strict: default_action=tempfail. The journal milter keeps
  its socket and stays fail-open. postfix-wrapper waits for the new socket.
- It reads no database: what an application may send as comes from Postfix's
  own sender_login_maps, what the server signs for from OpenDKIM's
  SigningTable. Both are read again when they change; one that cannot be
  read defers mail.
- One From: field, one address, allowed by the envelope's lookup; then no
  other name of the SigningTable may appear anywhere in the raw line.
  Refused: 550 5.7.1 naming the line, reduced to printable ASCII.
- A refusal is a send-log row with reason "from" and the header address
  (migration 0006), written by another goroutine and not waited for. The
  journal's refusals record their reason too (limit, client), and the
  notifier takes only a limit's.

What it costs (docs/plans/from-header-binding.md, Statistics)
- The role marks itself alive every 2 s; at start the gap since the mark is
  downtime, counted from Postfix's start if later and not at all when
  supervisord says Postfix is not running.
- The log tailer counts the connections Postfix turned away: a warning that
  names the socket, then milter-reject "Service unavailable" from the same
  smtpd. Seen on the stand: the client is refused from CONNECT on and leaves
  at AUTH (454), so no MAIL line is ever written.
- sender_check_days, a row per UTC day, kept a year.

Pages
- Health: the card "Sender check", the socket's row, and the cards layout -
  boxes numbered by importance in two stacks read in rows; the left stack
  polls, the three readings of the right one are swapped in by id.
- Outbound log: a refused row says why in its tag (wrong From, wrong client,
  rate-limited); the message's page shows the From: line and what the
  application may send as.
- Help: topic "Sender check", word for word the mockup's.

Found by the stand, fixed here: the names for the second look came from the
sender bindings, and a domain with a key and no application yet was not
among them.

e2e: negative_journal_milter_fail_open is gone - it proved that mail passes
with the panel down, which is no longer so. In its place
sender_check_holds_the_from_line (another domain's From:, the hostname's, a
stranger's, an address off the list, another sender in the display name -
refused; own addresses - delivered) and panel_down_defers_mail (4xx with the
panel stopped, the container alive, mail again after, downtime and one
deferred message on Health, the card warning).

Test server, this tree before the last cosmetic edits (a fixture row, a
fact's size, docs): go vet ok, go test 23 packages ok, make e2e ok (337 s).
Locally after them: internal/web/view ok.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
2026-10-12 19:35:43 +03:00