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caddytls: Evict internal certs from cache based on issuer (#6266)

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* caddytls: Evict internal certs from cache based on issuer

During a config reload, we would keep certs in the cache fi they were used  by the next config. If one config uses InternalIssuer and the other uses a public CA, this behavior is problematic / unintuitive, because there is a big difference between private/public CAs.

This change should ensure that internal issuers are considered when deciding whether to keep or evict from the cache during a reload, by making them distinct from each other and certs from public CAs.

* Make sure new TLS app manages configured certs

* Actually make it work
This commit is contained in:
Matt Holt 2024-04-30 16:15:54 -06:00 committed by GitHub
parent 87c7127c28
commit d129ae6aec
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GPG key ID: B5690EEEBB952194
3 changed files with 51 additions and 11 deletions
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2
go.mod
View file

@ -7,7 +7,7 @@ require (
github.com/Masterminds/sprig/v3 v3.2.3
github.com/alecthomas/chroma/v2 v2.13.0
github.com/aryann/difflib v0.0.0-20210328193216-ff5ff6dc229b
github.com/caddyserver/certmagic v0.20.1-0.20240419174353-855d4670a49d
github.com/caddyserver/certmagic v0.20.1-0.20240423172519-140a6fa9202e
github.com/caddyserver/zerossl v0.1.2
github.com/dustin/go-humanize v1.0.1
github.com/go-chi/chi/v5 v5.0.12

4
go.sum
View file

@ -68,8 +68,8 @@ github.com/aws/smithy-go v1.19.0 h1:KWFKQV80DpP3vJrrA9sVAHQ5gc2z8i4EzrLhLlWXcBM=
github.com/aws/smithy-go v1.19.0/go.mod h1:NukqUGpCZIILqqiV0NIjeFh24kd/FAa4beRb6nbIUPE=
github.com/beorn7/perks v1.0.1 h1:VlbKKnNfV8bJzeqoa4cOKqO6bYr3WgKZxO8Z16+hsOM=
github.com/beorn7/perks v1.0.1/go.mod h1:G2ZrVWU2WbWT9wwq4/hrbKbnv/1ERSJQ0ibhJ6rlkpw=
github.com/caddyserver/certmagic v0.20.1-0.20240419174353-855d4670a49d h1:fi1dMdHOoyWHXpxpCbaB+H4xdAgQcBP2AXSqpXVpIcg=
github.com/caddyserver/certmagic v0.20.1-0.20240419174353-855d4670a49d/go.mod h1:e1NhB1rF5KZnAuAX6oSyhE7sg1Ru5bWgggw5RtauhEY=
github.com/caddyserver/certmagic v0.20.1-0.20240423172519-140a6fa9202e h1:+D6CR2rMrHZe79HSwjgefZWP9y78FMQ2NygXvhF0XVA=
github.com/caddyserver/certmagic v0.20.1-0.20240423172519-140a6fa9202e/go.mod h1:e1NhB1rF5KZnAuAX6oSyhE7sg1Ru5bWgggw5RtauhEY=
github.com/caddyserver/zerossl v0.1.2 h1:tlEu1VzWGoqcCpivs9liKAKhfpJWYJkHEMmlxRbVAxE=
github.com/caddyserver/zerossl v0.1.2/go.mod h1:wtiJEHbdvunr40ZzhXlnIkOB8Xj4eKtBKizCcZitJiQ=
github.com/cenkalti/backoff/v4 v4.2.1 h1:y4OZtCnogmCPw98Zjyt5a6+QwPLGkiQsYW5oUqylYbM=

56
modules/caddytls/tls.go
View file

@ -91,7 +91,8 @@ type TLS struct {
// set of subjects with managed certificates,
// and hashes of manually-loaded certificates
managing, loaded map[string]struct{}
// (managing's value is an optional issuer key, for distinction)
managing, loaded map[string]string
}
// CaddyModule returns the Caddy module information.
@ -112,7 +113,7 @@ func (t *TLS) Provision(ctx caddy.Context) error {
t.ctx = ctx
t.logger = ctx.Logger()
repl := caddy.NewReplacer()
t.managing, t.loaded = make(map[string]struct{}), make(map[string]struct{})
t.managing, t.loaded = make(map[string]string), make(map[string]string)
// set up a new certificate cache; this (re)loads all certificates
cacheOpts := certmagic.CacheOptions{
@ -266,7 +267,7 @@ func (t *TLS) Provision(ctx caddy.Context) error {
if err != nil {
return fmt.Errorf("caching unmanaged certificate: %v", err)
}
t.loaded[hash] = struct{}{}
t.loaded[hash] = ""
}
}
@ -358,10 +359,27 @@ func (t *TLS) Cleanup() error {
// compute which certificates were managed or loaded into the cert cache by this
// app instance (which is being stopped) that are not managed or loaded by the
// new app instance (which just started), and remove them from the cache
var noLongerManaged, noLongerLoaded []string
for subj := range t.managing {
if _, ok := nextTLSApp.managing[subj]; !ok {
noLongerManaged = append(noLongerManaged, subj)
var noLongerManaged []certmagic.SubjectIssuer
var reManage, noLongerLoaded []string
for subj, currentIssuerKey := range t.managing {
// It's a bit nuanced: managed certs can sometimes be different enough that we have to
// swap them out for a different one, even if they are for the same subject/domain.
// We consider "private" certs (internal CA/locally-trusted/etc) to be significantly
// distinct from "public" certs (production CAs/globally-trusted/etc) because of the
// implications when it comes to actual deployments: switching between an internal CA
// and a production CA, for example, is quite significant. Switching from one public CA
// to another, however, is not, and for our purposes we consider those to be the same.
// Anyway, if the next TLS app does not manage a cert for this name at all, definitely
// remove it from the cache. But if it does, and it's not the same kind of issuer/CA
// as we have, also remove it, so that it can swap it out for the right one.
if nextIssuerKey, ok := nextTLSApp.managing[subj]; !ok || nextIssuerKey != currentIssuerKey {
// next app is not managing a cert for this domain at all or is using a different issuer, so remove it
noLongerManaged = append(noLongerManaged, certmagic.SubjectIssuer{Subject: subj, IssuerKey: currentIssuerKey})
// then, if the next app is managing a cert for this name, but with a different issuer, re-manage it
if ok && nextIssuerKey != currentIssuerKey {
reManage = append(reManage, subj)
}
}
}
for hash := range t.loaded {
@ -370,10 +388,19 @@ func (t *TLS) Cleanup() error {
}
}
// remove the certs
certCacheMu.RLock()
certCache.RemoveManaged(noLongerManaged)
certCache.Remove(noLongerLoaded)
certCacheMu.RUnlock()
// give the new TLS app a "kick" to manage certs that it is configured for
// with its own configuration instead of the one we just evicted
if err := nextTLSApp.Manage(reManage); err != nil {
t.logger.Error("re-managing unloaded certificates with new config",
zap.Strings("subjects", reManage),
zap.Error(err))
}
} else {
// no more TLS app running, so delete in-memory cert cache
certCache.Stop()
@ -407,7 +434,20 @@ func (t *TLS) Manage(names []string) error {
return fmt.Errorf("automate: manage %v: %v", names, err)
}
for _, name := range names {
t.managing[name] = struct{}{}
// certs that are issued solely by our internal issuer are a little bit of
// a special case: if you have an initial config that manages example.com
// using internal CA, then after testing it you switch to a production CA,
// you wouldn't want to keep using the same self-signed cert, obviously;
// so we differentiate these by associating the subject with its issuer key;
// we do this because CertMagic has no notion of "InternalIssuer" like we
// do, so we have to do this logic ourselves
var issuerKey string
if len(ap.Issuers) == 1 {
if intIss, ok := ap.Issuers[0].(*InternalIssuer); ok && intIss != nil {
issuerKey = intIss.IssuerKey()
}
}
t.managing[name] = issuerKey
}
}