Merge branch 'security' into 'main'

Security

See merge request etke.cc/postmoogle!34

README.md

@@ -254,6 +254,14 @@ If you want to change them - check available options in the help message (`!pm h
 
 ---
 
+* **!pm spamcheck:mx** - only accept email from servers which seem prepared to receive it (those having valid MX records) (`true` - enable, `false` - disable)
+* **!pm spamcheck:smtp** - only accept email from servers which seem prepared to receive it (those listening on an SMTP port) (`true` - enable, `false` - disable)
+* **!pm spamlist:emails** - Get or set `spamlist:emails` of the room (comma-separated list), eg: `spammer@example.com,sspam@example.org`
+* **!pm spamlist:hosts** - Get or set `spamlist:hosts` of the room (comma-separated list), eg: `spammer.com,scammer.com,morespam.com`
+* **!pm spamlist:mailboxes** - Get or set `spamlist:mailboxes` of the room (comma-separated list), eg: `notspam,noreply,no-reply`
+
+---
+
 * **!pm dkim** - Get DKIM signature
 * **!pm catch-all** - Configure catch-all mailbox
 * **!pm users** - Get or set allowed users patterns

bot/bot.go

@@ -73,7 +73,9 @@ func (b *Bot) Error(ctx context.Context, roomID id.RoomID, message string, args
 	b.log.Error(message, args...)
 	err := fmt.Errorf(message, args...)
 
+	if hub := sentry.GetHubFromContext(ctx); hub != nil {
 		sentry.GetHubFromContext(ctx).CaptureException(err)
+	}
 	if roomID != "" {
 		b.SendError(ctx, roomID, err.Error())
 	}

bot/command.go

@@ -143,6 +143,46 @@ func (b *Bot) initCommands() commandList {
 			sanitizer: utils.SanitizeBoolString,
 			allowed:   b.allowOwner,
 		},
+		{allowed: b.allowOwner}, // delimiter
+		{
+			key:         roomOptionSpamcheckMX,
+			description: "only accept email from servers which seem prepared to receive it (those having valid MX records) (`true` - enable, `false` - disable)",
+			sanitizer:   utils.SanitizeBoolString,
+			allowed:     b.allowOwner,
+		},
+		{
+			key:         roomOptionSpamcheckSMTP,
+			description: "only accept email from servers which seem prepared to receive it (those listening on an SMTP port) (`true` - enable, `false` - disable)",
+			sanitizer:   utils.SanitizeBoolString,
+			allowed:     b.allowOwner,
+		},
+		{
+			key: roomOptionSpamlistEmails,
+			description: fmt.Sprintf(
+				"Get or set `%s` of the room (comma-separated list), eg: `spammer@example.com,sspam@example.org`",
+				roomOptionSpamlistEmails,
+			),
+			sanitizer: utils.SanitizeStringSlice,
+			allowed:   b.allowOwner,
+		},
+		{
+			key: roomOptionSpamlistHosts,
+			description: fmt.Sprintf(
+				"Get or set `%s` of the room (comma-separated list), eg: `spammer.com,scammer.com,morespam.com`",
+				roomOptionSpamlistHosts,
+			),
+			sanitizer: utils.SanitizeStringSlice,
+			allowed:   b.allowOwner,
+		},
+		{
+			key: roomOptionSpamlistLocalparts,
+			description: fmt.Sprintf(
+				"Get or set `%s` of the room (comma-separated list), eg: `notspam,noreply,no-reply`",
+				roomOptionSpamlistLocalparts,
+			),
+			sanitizer: utils.SanitizeStringSlice,
+			allowed:   b.allowOwner,
+		},
 		{allowed: b.allowAdmin}, // delimiter
 		{
 			key:         botOptionUsers,

bot/email.go

@@ -59,6 +59,17 @@ func (b *Bot) GetMapping(mailbox string) (id.RoomID, bool) {
 	return roomID, ok
 }
 
+// GetIFOptions returns incoming email filtering options (room settings)
+func (b *Bot) GetIFOptions(roomID id.RoomID) utils.IncomingFilteringOptions {
+	cfg, err := b.getRoomSettings(roomID)
+	if err != nil {
+		b.log.Error("cannot retrieve room settings: %v", err)
+		return roomSettings{}
+	}
+
+	return cfg
+}
+
 // Send email to matrix room
 func (b *Bot) Send2Matrix(ctx context.Context, email *utils.Email, incoming bool) error {
 	roomID, ok := b.GetMapping(email.Mailbox(incoming))

bot/settings_room.go

@@ -23,6 +23,11 @@ const (
 	roomOptionNoThreads          = "nothreads"
 	roomOptionNoFiles            = "nofiles"
 	roomOptionPassword           = "password"
+	roomOptionSpamcheckSMTP      = "spamcheck:smtp"
+	roomOptionSpamcheckMX        = "spamcheck:mx"
+	roomOptionSpamlistEmails     = "spamlist:emails"
+	roomOptionSpamlistHosts      = "spamlist:hosts"
+	roomOptionSpamlistLocalparts = "spamlist:mailboxes"
 )
 
 type roomSettings map[string]string
@@ -77,6 +82,26 @@ func (s roomSettings) NoFiles() bool {
 	return utils.Bool(s.Get(roomOptionNoFiles))
 }
 
+func (s roomSettings) SpamcheckSMTP() bool {
+	return utils.Bool(s.Get(roomOptionSpamcheckSMTP))
+}
+
+func (s roomSettings) SpamcheckMX() bool {
+	return utils.Bool(s.Get(roomOptionSpamcheckMX))
+}
+
+func (s roomSettings) SpamlistEmails() []string {
+	return utils.StringSlice(s.Get(roomOptionSpamlistEmails))
+}
+
+func (s roomSettings) SpamlistHosts() []string {
+	return utils.StringSlice(s.Get(roomOptionSpamlistHosts))
+}
+
+func (s roomSettings) SpamlistLocalparts() []string {
+	return utils.StringSlice(s.Get(roomOptionSpamlistLocalparts))
+}
+
 // ContentOptions converts room display settings to content options
 func (s roomSettings) ContentOptions() *utils.ContentOptions {
 	return &utils.ContentOptions{

go.mod

@@ -19,6 +19,7 @@ require (
 	gitlab.com/etke.cc/go/mxidwc v1.0.0
 	gitlab.com/etke.cc/go/secgen v1.1.1
 	gitlab.com/etke.cc/go/trysmtp v1.0.0
+	gitlab.com/etke.cc/go/validator v1.0.1
 	gitlab.com/etke.cc/linkpearl v0.0.0-20221008191655-865ae3362a01
 	golang.org/x/net v0.0.0-20221004154528-8021a29435af
 	maunium.net/go/mautrix v0.12.1

go.sum

@@ -97,6 +97,8 @@ gitlab.com/etke.cc/go/secgen v1.1.1 h1:RmKOki725HIhWJHzPtAc9X4YvBneczndchpMgoDkE
 gitlab.com/etke.cc/go/secgen v1.1.1/go.mod h1:3pJqRGeWApzx7qXjABqz2o2SMCNpKSZao/gXVdasqE8=
 gitlab.com/etke.cc/go/trysmtp v1.0.0 h1:f/7gSmzohKniVeLSLevI+ZsySYcPUGkT9cRlOTwjOr8=
 gitlab.com/etke.cc/go/trysmtp v1.0.0/go.mod h1:KqRuIB2IPElEEbAxXmFyKtm7S5YiuEb4lxwWthccqyE=
+gitlab.com/etke.cc/go/validator v1.0.1 h1:xp1tAzgCu9A1pga8rFUo7hODaEcCR1nkkodw96+dYuA=
+gitlab.com/etke.cc/go/validator v1.0.1/go.mod h1:3vdssRG4LwgdTr9IHz9MjGSEO+3/FO9hXPGMuSeweJ8=
 gitlab.com/etke.cc/linkpearl v0.0.0-20221008191655-865ae3362a01 h1:rlcxjSCCG18sbNT2CsCRKjtwQ2UjkuTutkRHSCGhhxs=
 gitlab.com/etke.cc/linkpearl v0.0.0-20221008191655-865ae3362a01/go.mod h1:HkUHUkhbkDueEJVc7h/zBfz2hjhl4xxjQKv9Itrdf9k=
 golang.org/x/crypto v0.0.0-20220518034528-6f7dac969898/go.mod h1:IxCIyHEi3zRg3s0A5j5BB6A9Jmi73HwBIUl50j+osU4=

smtp/msasession.go

@@ -9,6 +9,7 @@ import (
 	"github.com/getsentry/sentry-go"
 	"github.com/jhillyerd/enmime"
 	"gitlab.com/etke.cc/go/logger"
+	"gitlab.com/etke.cc/go/validator"
 
 	"gitlab.com/etke.cc/postmoogle/utils"
 )
@@ -43,6 +44,7 @@ func (s *msasession) Mail(from string, opts smtp.MailOptions) error {
 
 func (s *msasession) Rcpt(to string) error {
 	sentry.GetHubFromContext(s.ctx).Scope().SetTag("to", to)
+	s.to = to
 
 	if s.incoming {
 		if utils.Hostname(to) != s.domain {
@@ -50,14 +52,18 @@ func (s *msasession) Rcpt(to string) error {
 			return smtp.ErrAuthRequired
 		}
 
-		_, ok := s.bot.GetMapping(utils.Mailbox(to))
+		roomID, ok := s.bot.GetMapping(utils.Mailbox(to))
 		if !ok {
 			s.log.Debug("mapping for %s not found", to)
 			return smtp.ErrAuthRequired
 		}
+
+		validations := s.bot.GetIFOptions(roomID)
+		if !s.validate(validations) {
+			return smtp.ErrAuthRequired
+		}
 	}
 
-	s.to = to
 	s.log.Debug("mail to %s", to)
 	return nil
 }
@@ -75,6 +81,21 @@ func (s *msasession) parseAttachments(parts []*enmime.Part) []*utils.File {
 	return files
 }
 
+func (s *msasession) validate(options utils.IncomingFilteringOptions) bool {
+	spam := validator.Spam{
+		Emails:     options.SpamlistEmails(),
+		Hosts:      options.SpamlistHosts(),
+		Localparts: options.SpamlistLocalparts(),
+	}
+	enforce := validator.Enforce{
+		MX:   options.SpamcheckMX(),
+		SMTP: options.SpamcheckMX(),
+	}
+	v := validator.New(spam, enforce, s.to, s.log)
+
+	return v.Email(s.from)
+}
+
 func (s *msasession) Data(r io.Reader) error {
 	parser := enmime.NewParser()
 	eml, err := parser.ReadEnvelope(r)

smtp/mta.go

@@ -16,6 +16,7 @@ import (
 type Bot interface {
 	AllowAuth(string, string) bool
 	GetMapping(string) (id.RoomID, bool)
+	GetIFOptions(id.RoomID) utils.IncomingFilteringOptions
 	Send2Matrix(ctx context.Context, email *utils.Email, incoming bool) error
 	SetMTA(mta utils.MTA)
 }

utils/email.go

@@ -19,6 +19,15 @@ type MTA interface {
 	Send(from, to, data string) error
 }
 
+// IncomingFilteringOptions for incoming mail
+type IncomingFilteringOptions interface {
+	SpamcheckSMTP() bool
+	SpamcheckMX() bool
+	SpamlistEmails() []string
+	SpamlistHosts() []string
+	SpamlistLocalparts() []string
+}
+
 // Email object
 type Email struct {
 	Date      string

utils/utils.go

@@ -33,3 +33,31 @@ func Bool(str string) bool {
 func SanitizeBoolString(str string) string {
 	return strconv.FormatBool(Bool(str))
 }
+
+// StringSlice converts comma-separated string to slice
+func StringSlice(str string) []string {
+	if str == "" {
+		return nil
+	}
+
+	str = strings.TrimSpace(str)
+	if strings.IndexByte(str, ',') == -1 {
+		return []string{str}
+	}
+
+	return strings.Split(str, ",")
+}
+
+// SanitizeBoolString converts string to slice and back to string
+func SanitizeStringSlice(str string) string {
+	parts := StringSlice(str)
+	if len(parts) == 0 {
+		return str
+	}
+
+	for i, part := range parts {
+		parts[i] = strings.TrimSpace(part)
+	}
+
+	return strings.Join(parts, ",")
+}