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implement outgoing tls reports

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we were already accepting, processing and displaying incoming tls reports. now
we start tracking TLS connection and security-policy-related errors for
outgoing message deliveries as well. we send reports once a day, to the
reporting addresses specified in TLSRPT records (rua) of a policy domain. these
reports are about MTA-STS policies and/or DANE policies, and about
STARTTLS-related failures.

sending reports is enabled by default, but can be disabled through setting
NoOutgoingTLSReports in mox.conf.

only at the end of the implementation process came the realization that the
TLSRPT policy domain for DANE (MX) hosts are separate from the TLSRPT policy
for the recipient domain, and that MTA-STS and DANE TLS/policy results are
typically delivered in separate reports. so MX hosts need their own TLSRPT
policies.

config for the per-host TLSRPT policy should be added to mox.conf for existing
installs, in field HostTLSRPT. it is automatically configured by quickstart for
new installs. with a HostTLSRPT config, the "dns records" and "dns check" admin
pages now suggest the per-host TLSRPT record. by creating that record, you're
requesting TLS reports about your MX host.

gathering all the TLS/policy results is somewhat tricky. the tentacles go
throughout the code. the positive result is that the TLS/policy-related code
had to be cleaned up a bit. for example, the smtpclient TLS modes now reflect
reality better, with independent settings about whether PKIX and/or DANE
verification has to be done, and/or whether verification errors have to be
ignored (e.g. for tls-required: no header). also, cached mtasts policies of
mode "none" are now cleaned up once the MTA-STS DNS record goes away.
This commit is contained in:
Mechiel Lukkien
2023-11-09 17:40:46 +01:00
parent df18ca3c02
commit 893a6f8911
58 changed files with 3246 additions and 504 deletions
Download Patch File Download Diff File Expand all files Collapse all files

65
queue/queue.go
View File

@ -32,6 +32,8 @@ import (
"github.com/mjl-/mox/smtp"
"github.com/mjl-/mox/smtpclient"
"github.com/mjl-/mox/store"
"github.com/mjl-/mox/tlsrpt"
"github.com/mjl-/mox/tlsrptdb"
)
var xlog = mlog.New("queue")
@ -55,7 +57,7 @@ var (
[]string{
"attempt", // Number of attempts.
"transport", // empty for default direct delivery.
"tlsmode", // strict, opportunistic, skip
"tlsmode", // immediate, requiredstarttls, opportunistic, skip (from smtpclient.TLSMode), with optional +mtasts and/or +dane.
"result", // ok, timeout, canceled, temperror, permerror, error
},
)
@ -580,12 +582,71 @@ func deliver(resolver dns.Resolver, m Msg) {
qlog.Debug("delivering with transport", mlog.Field("transport", transportName))
}
// We gather TLS connection successes and failures during delivery, and we store
// them in tlsrptb. Every 24 hours we send an email with a report to the recipient
// domains that opt in via a TLSRPT DNS record. For us, the tricky part is
// collecting all reporting information. We've got several TLS modes
// (opportunistic, DANE and/or MTA-STS (PKIX), overrides due to Require TLS).
// Failures can happen at various levels: MTA-STS policies (apply to whole delivery
// attempt/domain), MX targets (possibly multiple per delivery attempt, both for
// MTA-STS and DANE).
//
// Once the SMTP client has tried a TLS handshake, we register success/failure,
// regardless of what happens next on the connection. We also register failures
// when they happen before we get to the SMTP client, but only if they are related
// to TLS (and some DNSSEC).
var recipientDomainResult tlsrpt.Result
var hostResults []tlsrpt.Result
defer func() {
if mox.Conf.Static.NoOutgoingTLSReports || !m.RecipientDomain.IsDomain() {
return
}
now := time.Now()
dayUTC := now.UTC().Format("20060102")
results := make([]tlsrptdb.TLSResult, 0, 1+len(hostResults))
addResult := func(r tlsrpt.Result, isHost bool) {
var zerotype tlsrpt.PolicyType
if r.Policy.Type == zerotype {
return
}
// Ensure we store policy domain in unicode in database.
policyDomain, err := dns.ParseDomain(r.Policy.Domain)
if err != nil {
qlog.Errorx("parsing policy domain for tls result", err, mlog.Field("policydomain", r.Policy.Domain))
return
}
tlsResult := tlsrptdb.TLSResult{
PolicyDomain: policyDomain.Name(),
DayUTC: dayUTC,
RecipientDomain: m.RecipientDomain.Domain.Name(),
IsHost: isHost,
SendReport: !m.IsTLSReport,
Results: []tlsrpt.Result{r},
}
results = append(results, tlsResult)
}
addResult(recipientDomainResult, false)
for _, result := range hostResults {
addResult(result, true)
}
if len(results) > 0 {
err := tlsrptdb.AddTLSResults(context.Background(), results)
qlog.Check(err, "adding tls results to database for upcoming tlsrpt report")
}
}()
var dialer smtpclient.Dialer = &net.Dialer{}
if transport.Submissions != nil {
deliverSubmit(cid, qlog, resolver, dialer, m, backoff, transportName, transport.Submissions, true, 465)
} else if transport.Submission != nil {
deliverSubmit(cid, qlog, resolver, dialer, m, backoff, transportName, transport.Submission, false, 587)
} else if transport.SMTP != nil {
// todo future: perhaps also gather tlsrpt results for submissions.
deliverSubmit(cid, qlog, resolver, dialer, m, backoff, transportName, transport.SMTP, false, 25)
} else {
ourHostname := mox.Conf.Static.HostnameDomain
@ -602,7 +663,7 @@ func deliver(resolver dns.Resolver, m Msg) {
}
ourHostname = transport.Socks.Hostname
}
deliverDirect(cid, qlog, resolver, dialer, ourHostname, transportName, m, backoff)
recipientDomainResult, hostResults = deliverDirect(cid, qlog, resolver, dialer, ourHostname, transportName, m, backoff)
}
}