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implement "requiretls", rfc 8689

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with requiretls, the tls verification mode/rules for email deliveries can be
changed by the sender/submitter. in two ways:

1. "requiretls" smtp extension to always enforce verified tls (with mta-sts or
dnssec+dane), along the entire delivery path until delivery into the final
destination mailbox (so entire transport is verified-tls-protected).

2. "tls-required: no" message header, to ignore any tls and tls verification
errors even if the recipient domain has a policy that requires tls verification
(mta-sts and/or dnssec+dane), allowing delivery of non-sensitive messages in
case of misconfiguration/interoperability issues (at least useful for sending
tls reports).

we enable requiretls by default (only when tls is active), for smtp and
submission. it can be disabled through the config.

for each delivery attempt, we now store (per recipient domain, in the account
of the sender) whether the smtp server supports starttls and requiretls. this
support is shown (after having sent a first message) in the webmail when
sending a message (the previous 3 bars under the address input field are now 5
bars, the first for starttls support, the last for requiretls support). when
all recipient domains for a message are known to implement requiretls,
requiretls is automatically selected for sending (instead of "default" tls
behaviour). users can also select the "fallback to insecure" to add the
"tls-required: no" header.

new metrics are added for insight into requiretls errors and (some, not yet
all) cases where tls-required-no ignored a tls/verification error.

the admin can change the requiretls status for messages in the queue. so with
default delivery attempts, when verified tls is required by failing, an admin
could potentially change the field to "tls-required: no"-behaviour.

messages received (over smtp) with the requiretls option, get a comment added
to their Received header line, just before "id", after "with".
This commit is contained in:
Mechiel Lukkien
2023-10-24 10:06:16 +02:00
parent 0e5e16b3d0
commit 2f5d6069bf
31 changed files with 1102 additions and 274 deletions
Download Patch File Download Diff File Expand all files Collapse all files

104
webmail/webmail.ts
View File

@ -52,7 +52,7 @@ To simulate slow API calls and SSE events:
Show additional headers of messages:
settingsPut({...settings, showHeaders: ['User-Agent', 'X-Mailer', 'Message-Id', 'List-Id', 'List-Post', 'X-Mox-Reason']})
settingsPut({...settings, showHeaders: ['User-Agent', 'X-Mailer', 'Message-Id', 'List-Id', 'List-Post', 'X-Mox-Reason', 'TLS-Required']})
Enable logging and reload afterwards:
@ -1154,6 +1154,8 @@ const compose = (opts: ComposeOptions) => {
type AddrView = {
root: HTMLElement
input: HTMLInputElement
isRecipient: boolean
recipientSecurity: null | api.RecipientSecurity
}
let fieldset: HTMLFieldSetElement
@ -1163,6 +1165,7 @@ const compose = (opts: ComposeOptions) => {
let subject: HTMLInputElement
let body: HTMLTextAreaElement
let attachments: HTMLInputElement
let requiretls: HTMLSelectElement
let toBtn: HTMLButtonElement, ccBtn: HTMLButtonElement, bccBtn: HTMLButtonElement, replyToBtn: HTMLButtonElement, customFromBtn: HTMLButtonElement
let replyToCell: HTMLElement, toCell: HTMLElement, ccCell: HTMLElement, bccCell: HTMLElement // Where we append new address views.
@ -1217,6 +1220,7 @@ const compose = (opts: ComposeOptions) => {
ForwardAttachments: forwardAttachmentPaths.length === 0 ? {MessageID: 0, Paths: []} : {MessageID: opts.attachmentsMessageItem!.Message.ID, Paths: forwardAttachmentPaths},
IsForward: opts.isForward || false,
ResponseMessageID: opts.responseMessageID || 0,
RequireTLS: requiretls.value === '' ? null : requiretls.value === 'yes',
}
await client.MessageSubmit(message)
cmdCancel()
@ -1226,10 +1230,10 @@ const compose = (opts: ComposeOptions) => {
await withStatus('Sending email', submit(), fieldset)
}
const cmdAddTo = async () => { newAddrView('', toViews, toBtn, toCell, toRow) }
const cmdAddCc = async () => { newAddrView('', ccViews, ccBtn, ccCell, ccRow) }
const cmdAddBcc = async () => { newAddrView('', bccViews, bccBtn, bccCell, bccRow) }
const cmdReplyTo = async () => { newAddrView('', replytoViews, replyToBtn, replyToCell, replyToRow, true) }
const cmdAddTo = async () => { newAddrView('', true, toViews, toBtn, toCell, toRow) }
const cmdAddCc = async () => { newAddrView('', true, ccViews, ccBtn, ccCell, ccRow) }
const cmdAddBcc = async () => { newAddrView('', true, bccViews, bccBtn, bccCell, bccRow) }
const cmdReplyTo = async () => { newAddrView('', false, replytoViews, replyToBtn, replyToCell, replyToRow, true) }
const cmdCustomFrom = async () => {
if (customFrom) {
return
@ -1249,7 +1253,7 @@ const compose = (opts: ComposeOptions) => {
// ctrl - and ctrl = (+) not included, they are handled by keydown handlers on in the inputs they remove/add.
}
const newAddrView = (addr: string, views: AddrView[], btn: HTMLButtonElement, cell: HTMLElement, row: HTMLElement, single?: boolean) => {
const newAddrView = (addr: string, isRecipient: boolean, views: AddrView[], btn: HTMLButtonElement, cell: HTMLElement, row: HTMLElement, single?: boolean) => {
if (single && views.length !== 0) {
return
}
@ -1285,11 +1289,13 @@ const compose = (opts: ComposeOptions) => {
}
return '#aaa'
}
const setBar = (c0: string, c1: string, c2: string) => {
const setBar = (c0: string, c1: string, c2: string, c3: string, c4: string) => {
const stops = [
c0 + ' 0%', c0 + ' 32%', 'white 32%', 'white 33%',
c1 + ' 33%', c1 + ' 66%', 'white 66%', 'white 67%',
c2 + ' 67%', c2 + ' 100%',
c0 + ' 0%', c0 + ' 19%', 'white 19%', 'white 20%',
c1 + ' 20%', c1 + ' 39%', 'white 39%', 'white 40%',
c2 + ' 40%', c2 + ' 59%', 'white 59%', 'white 60%',
c3 + ' 60%', c3 + ' 79%', 'white 79%', 'white 80%',
c4 + ' 80%', c4 + ' 100%',
].join(', ')
securityBar.style.borderImage = 'linear-gradient(to right, ' + stops + ') 1'
}
@ -1298,14 +1304,53 @@ const compose = (opts: ComposeOptions) => {
rcptSecAborter = aborter
rcptSecPromise = client.withOptions({aborter: aborter}).RecipientSecurity(inputElem.value)
rcptSecPromise.then((rs) => {
setBar(color(rs.MTASTS), color(rs.DNSSEC), color(rs.DANE))
setBar(color(rs.STARTTLS), color(rs.MTASTS), color(rs.DNSSEC), color(rs.DANE), color(rs.RequireTLS))
const implemented: string[] = []
const check = (v: boolean, s: string) => {
if (v) {
implemented.push(s)
}
}
check(rs.STARTTLS === api.SecurityResult.SecurityResultYes, 'STARTTLS')
check(rs.MTASTS === api.SecurityResult.SecurityResultYes, 'MTASTS')
check(rs.DNSSEC === api.SecurityResult.SecurityResultYes, 'DNSSEC')
check(rs.DANE === api.SecurityResult.SecurityResultYes, 'DANE')
check(rs.RequireTLS === api.SecurityResult.SecurityResultYes, 'RequireTLS')
const status = 'Security mechanisms known to be implemented by the recipient domain: '+ (implemented.length === 0 ? '(none)' : implemented.join(', ')) + '.'
inputElem.setAttribute('title', status+'\n\n'+recipientSecurityTitle)
aborter.abort = undefined
v.recipientSecurity = rs
if (isRecipient) {
// If all recipients implement REQUIRETLS, we can enable it.
let reqtls = true
const walk = (l: AddrView[]) => {
for (const v of l) {
if (v.recipientSecurity?.RequireTLS !== api.SecurityResult.SecurityResultYes) {
reqtls = false
break
}
}
}
walk(toViews)
walk(ccViews)
walk(bccViews)
if (requiretls.value === '' || requiretls.value === 'yes') {
requiretls.value = reqtls ? 'yes' : ''
}
}
}, () => {
setBar('#888', '#888', '#888')
setBar('#888', '#888', '#888', '#888', '#888')
inputElem.setAttribute('title', 'Error fetching security mechanisms known to be implemented by the recipient domain...\n\n'+recipientSecurityTitle)
aborter.abort = undefined
if (requiretls.value === 'yes') {
requiretls.value = ''
}
})
}
const recipientSecurityTitle = 'Description of security mechanisms recipient domains may implement:\n1. STARTTLS: Opportunistic (unverified) TLS with STARTTLS, successfully negotiated during the most recent delivery attempt.\n2. MTA-STS: For PKIX/WebPKI-verified TLS.\n3. DNSSEC: MX DNS records are DNSSEC-signed.\n4. DANE: First delivery destination host implements DANE for verified TLS.\n5. RequireTLS: SMTP extension for verified TLS delivery into recipient mailbox, support detected during the most recent delivery attempt.\n\nChecks STARTTLS, DANE and RequireTLS cover the most recently used delivery path, not necessarily all possible delivery paths.\n\nThe bars below the input field indicate implementation status by the recipient domain:\n- Red, not implemented/unsupported\n- Green, implemented/supported\n- Gray, error while determining\n- Absent/white, unknown or skipped (e.g. no previous delivery attempt, or DANE check skipped due to DNSSEC-lookup error)'
const root = dom.span(
autosizeElem=dom.span(
dom._class('autosize'),
@ -1314,12 +1359,12 @@ const compose = (opts: ComposeOptions) => {
style({width: 'auto'}),
attr.value(addr),
newAddressComplete(),
attr.title('The bars below the input field indicate security features of the recipient (domain):\n1. Delivery with STARTTLS and MTA-STS (PKIX/WebPKI) enforced.\n2. MX lookup resulted in DNSSEC-signed response.\n3. First delivery destination host has DANE, so STARTTLS is required.\n\nColors:\n- Red, not implemented/unsupported\n- Green, implemented/supported\n- Gray, error while determining\n- Absent/white, unknown or skipped (e.g. dane check skipped due to dnssec-lookup error)'),
attr.title(recipientSecurityTitle),
function keydown(e: KeyboardEvent) {
if (e.key === '-' && e.ctrlKey) {
remove()
} else if (e.key === '=' && e.ctrlKey) {
newAddrView('', views, btn, cell, row, single)
newAddrView('', isRecipient, views, btn, cell, row, single)
} else {
return
}
@ -1353,7 +1398,6 @@ const compose = (opts: ComposeOptions) => {
' ',
)
autosizeElem.dataset.value = inputElem.value
fetchRecipientSecurity()
const remove = () => {
const i = views.indexOf(v)
@ -1383,7 +1427,10 @@ const compose = (opts: ComposeOptions) => {
}
}
const v: AddrView = {root: root, input: inputElem}
const v: AddrView = {root: root, input: inputElem, isRecipient: isRecipient, recipientSecurity: null}
fetchRecipientSecurity()
views.push(v)
cell.appendChild(v.root)
row.style.display = ''
@ -1541,8 +1588,21 @@ const compose = (opts: ComposeOptions) => {
}), ' (Toggle all)')
),
noAttachmentsWarning=dom.div(style({display: 'none', backgroundColor: '#fcd284', padding: '0.15em .25em', margin: '.5em 0'}), 'Message mentions attachments, but no files are attached.'),
dom.div(style({margin: '1ex 0'}), 'Attachments ', attachments=dom.input(attr.type('file'), attr.multiple(''), function change() { checkAttachments() })),
dom.submitbutton('Send'),
dom.label(style({margin: '1ex 0', display: 'block'}), 'Attachments ', attachments=dom.input(attr.type('file'), attr.multiple(''), function change() { checkAttachments() })),
dom.label(
style({margin: '1ex 0', display: 'block'}),
attr.title('How to use TLS for message delivery over SMTP:\n\nDefault: Delivery attempts follow the policies published by the recipient domain: Verification with MTA-STS and/or DANE, or optional opportunistic unverified STARTTLS if the domain does not specify a policy.\n\nWith RequireTLS: For sensitive messages, you may want to require verified TLS. The recipient destination domain SMTP server must support the REQUIRETLS SMTP extension for delivery to succeed. It is automatically chosen when the destination domain mail servers of all recipients are known to support it.\n\nFallback to insecure: If delivery fails due to MTA-STS and/or DANE policies specified by the recipient domain, and the content is not sensitive, you may choose to ignore the recipient domain TLS policies so delivery can succeed.'),
'TLS ',
requiretls=dom.select(
dom.option(attr.value(''), 'Default'),
dom.option(attr.value('yes'), 'With RequireTLS'),
dom.option(attr.value('no'), 'Fallback to insecure'),
),
),
dom.div(
style({margin: '3ex 0 1ex 0', display: 'block'}),
dom.submitbutton('Send'),
),
),
async function submit(e: SubmitEvent) {
e.preventDefault()
@ -1553,11 +1613,11 @@ const compose = (opts: ComposeOptions) => {
subjectAutosize.dataset.value = subject.value
;(opts.to && opts.to.length > 0 ? opts.to : ['']).forEach(s => newAddrView(s, toViews, toBtn, toCell, toRow))
;(opts.cc || []).forEach(s => newAddrView(s, ccViews, ccBtn, ccCell, ccRow))
;(opts.bcc || []).forEach(s => newAddrView(s, bccViews, bccBtn, bccCell, bccRow))
;(opts.to && opts.to.length > 0 ? opts.to : ['']).forEach(s => newAddrView(s, true, toViews, toBtn, toCell, toRow))
;(opts.cc || []).forEach(s => newAddrView(s,true, ccViews, ccBtn, ccCell, ccRow))
;(opts.bcc || []).forEach(s => newAddrView(s, true, bccViews, bccBtn, bccCell, bccRow))
if (opts.replyto) {
newAddrView(opts.replyto, replytoViews, replyToBtn, replyToCell, replyToRow, true)
newAddrView(opts.replyto, false, replytoViews, replyToBtn, replyToCell, replyToRow, true)
}
if (!opts.cc || !opts.cc.length) {
ccRow.style.display = 'none'