mirror of
https://github.com/safing/portmaster
synced 2025-09-02 10:39:22 +00:00
363 lines
9.8 KiB
Go
363 lines
9.8 KiB
Go
package firewall
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import (
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"fmt"
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"net"
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"os"
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"path/filepath"
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"strings"
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"github.com/safing/portbase/log"
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"github.com/safing/portmaster/network"
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"github.com/safing/portmaster/network/netutils"
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"github.com/safing/portmaster/network/packet"
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"github.com/safing/portmaster/process"
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"github.com/safing/portmaster/profile"
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"github.com/safing/portmaster/profile/endpoints"
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"github.com/safing/portmaster/resolver"
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"github.com/agext/levenshtein"
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"github.com/miekg/dns"
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)
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// Call order:
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//
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// DNS Query:
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// 1. DecideOnConnection
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// is called when a DNS query is made, may set verdict to Undeterminable to permit a DNS reply.
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// is called with a nil packet.
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// 2. FilterDNSResponse
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// is called to (possibly) filter out A/AAAA records that the filter would deny later.
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//
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// Network Connection:
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// 3. DecideOnConnection
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// is called with the first packet of a network connection.
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// DecideOnConnection makes a decision about a connection.
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// When called, the connection and profile is already locked.
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func DecideOnConnection(conn *network.Connection, pkt packet.Packet) { //nolint:gocognit,gocyclo // TODO
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// update profiles and check if communication needs reevaluation
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if conn.UpdateAndCheck() {
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log.Infof("filter: re-evaluating verdict on %s", conn)
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conn.Verdict = network.VerdictUndecided
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//if conn.Entity != nil {
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//conn.Entity.ResetLists()
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//}
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}
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// grant self
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if conn.Process().Pid == os.Getpid() {
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log.Infof("filter: granting own connection %s", conn)
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conn.Verdict = network.VerdictAccept
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return
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}
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// check if process is communicating with itself
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if pkt != nil {
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// TODO: evaluate the case where different IPs in the 127/8 net are used.
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pktInfo := pkt.Info()
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if conn.Process().Pid >= 0 && pktInfo.Src.Equal(pktInfo.Dst) {
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// get PID
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otherPid, _, err := process.GetPidByEndpoints(
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pktInfo.RemoteIP(),
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pktInfo.RemotePort(),
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pktInfo.LocalIP(),
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pktInfo.LocalPort(),
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pktInfo.Protocol,
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)
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if err != nil {
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log.Warningf("filter: failed to find local peer process PID: %s", err)
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} else {
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// get primary process
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otherProcess, err := process.GetOrFindPrimaryProcess(pkt.Ctx(), otherPid)
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if err != nil {
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log.Warningf("filter: failed to find load local peer process with PID %d: %s", otherPid, err)
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} else if otherProcess.Pid == conn.Process().Pid {
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conn.Accept("connection to self")
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return
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}
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}
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}
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}
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// get profile
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p := conn.Process().Profile()
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if p == nil {
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conn.Block("no profile")
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return
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}
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// check conn type
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switch conn.Scope {
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case network.IncomingHost, network.IncomingLAN, network.IncomingInternet, network.IncomingInvalid:
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if p.BlockInbound() {
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if conn.Scope == network.IncomingHost {
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conn.Block("inbound connections blocked")
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} else {
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conn.Drop("inbound connections blocked")
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}
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return
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}
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case network.PeerLAN, network.PeerInternet, network.PeerInvalid:
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// Important: PeerHost is and should be missing!
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if p.BlockP2P() {
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conn.Block("direct connections (P2P) blocked")
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return
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}
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}
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// check scopes
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if conn.Entity.IP != nil {
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classification := netutils.ClassifyIP(conn.Entity.IP)
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switch classification {
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case netutils.Global, netutils.GlobalMulticast:
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if p.BlockScopeInternet() {
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conn.Deny("Internet access blocked") // Block Outbound / Drop Inbound
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return
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}
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case netutils.SiteLocal, netutils.LinkLocal, netutils.LocalMulticast:
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if p.BlockScopeLAN() {
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conn.Block("LAN access blocked") // Block Outbound / Drop Inbound
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return
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}
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case netutils.HostLocal:
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if p.BlockScopeLocal() {
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conn.Block("Localhost access blocked") // Block Outbound / Drop Inbound
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return
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}
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default: // netutils.Invalid
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conn.Deny("invalid IP") // Block Outbound / Drop Inbound
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return
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}
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} else if conn.Entity.Domain != "" {
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// DNS Query
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// DNS is expected to resolve to LAN or Internet addresses
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// TODO: handle domains mapped to localhost
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if p.BlockScopeInternet() && p.BlockScopeLAN() {
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conn.Block("Internet and LAN access blocked")
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return
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}
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}
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// check endpoints list
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var result endpoints.EPResult
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var reason string
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if conn.Inbound {
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result, reason = p.MatchServiceEndpoint(conn.Entity)
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} else {
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result, reason = p.MatchEndpoint(conn.Entity)
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}
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switch result {
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case endpoints.Denied:
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conn.Deny("endpoint is blacklisted: " + reason) // Block Outbound / Drop Inbound
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return
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case endpoints.Permitted:
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conn.Accept("endpoint is whitelisted: " + reason)
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return
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}
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// continuing with result == NoMatch
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// apply privacy filter lists
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result, reason = p.MatchFilterLists(conn.Entity)
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switch result {
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case endpoints.Denied:
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conn.Deny("endpoint in filterlists: " + reason)
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return
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case endpoints.NoMatch:
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// nothing to do
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default:
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log.Debugf("filter: filter lists returned unsupported verdict: %s", result)
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}
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// implicit default=block for inbound
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if conn.Inbound {
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conn.Drop("endpoint is not whitelisted (incoming is always default=block)")
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return
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}
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// check default action
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if p.DefaultAction() == profile.DefaultActionPermit {
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conn.Accept("endpoint is not blacklisted (default=permit)")
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return
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}
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// check relation
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if !p.DisableAutoPermit() {
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related, reason := checkRelation(conn)
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if related {
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conn.Accept(reason)
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return
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}
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}
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// prompt
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if p.DefaultAction() == profile.DefaultActionAsk {
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prompt(conn, pkt)
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return
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}
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// DefaultAction == DefaultActionBlock
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conn.Deny("endpoint is not whitelisted (default=block)")
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}
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// FilterDNSResponse filters a dns response according to the application profile and settings.
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func FilterDNSResponse(conn *network.Connection, q *resolver.Query, rrCache *resolver.RRCache) *resolver.RRCache { //nolint:gocognit // TODO
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// do not modify own queries
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if conn.Process().Pid == os.Getpid() {
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return rrCache
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}
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// get profile
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p := conn.Process().Profile()
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if p == nil {
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conn.Block("no profile")
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return nil
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}
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// check if DNS response filtering is completely turned off
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if !p.RemoveOutOfScopeDNS() && !p.RemoveBlockedDNS() {
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return rrCache
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}
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// duplicate entry
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rrCache = rrCache.ShallowCopy()
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rrCache.FilteredEntries = make([]string, 0)
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// change information
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var addressesRemoved int
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var addressesOk int
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// loop vars
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var classification int8
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var ip net.IP
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// filter function
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filterEntries := func(entries []dns.RR) (goodEntries []dns.RR) {
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goodEntries = make([]dns.RR, 0, len(entries))
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for _, rr := range entries {
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// get IP and classification
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switch v := rr.(type) {
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case *dns.A:
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ip = v.A
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case *dns.AAAA:
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ip = v.AAAA
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default:
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// add non A/AAAA entries
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goodEntries = append(goodEntries, rr)
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continue
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}
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classification = netutils.ClassifyIP(ip)
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if p.RemoveOutOfScopeDNS() {
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switch {
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case classification == netutils.HostLocal:
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// No DNS should return localhost addresses
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addressesRemoved++
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rrCache.FilteredEntries = append(rrCache.FilteredEntries, rr.String())
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continue
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case rrCache.ServerScope == netutils.Global && (classification == netutils.SiteLocal || classification == netutils.LinkLocal):
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// No global DNS should return LAN addresses
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addressesRemoved++
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rrCache.FilteredEntries = append(rrCache.FilteredEntries, rr.String())
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continue
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}
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}
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if p.RemoveBlockedDNS() {
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// filter by flags
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switch {
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case p.BlockScopeInternet() && classification == netutils.Global:
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addressesRemoved++
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rrCache.FilteredEntries = append(rrCache.FilteredEntries, rr.String())
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continue
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case p.BlockScopeLAN() && (classification == netutils.SiteLocal || classification == netutils.LinkLocal):
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addressesRemoved++
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rrCache.FilteredEntries = append(rrCache.FilteredEntries, rr.String())
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continue
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case p.BlockScopeLocal() && classification == netutils.HostLocal:
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addressesRemoved++
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rrCache.FilteredEntries = append(rrCache.FilteredEntries, rr.String())
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continue
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}
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// TODO: filter by endpoint list (IP only)
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}
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// if survived, add to good entries
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addressesOk++
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goodEntries = append(goodEntries, rr)
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}
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return
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}
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rrCache.Answer = filterEntries(rrCache.Answer)
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rrCache.Extra = filterEntries(rrCache.Extra)
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if addressesRemoved > 0 {
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rrCache.Filtered = true
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if addressesOk == 0 {
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conn.Block("no addresses returned for this domain are permitted")
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return nil
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}
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}
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if rrCache.Filtered {
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log.Infof("filter: filtered DNS replies for %s: %s", conn, strings.Join(rrCache.FilteredEntries, ", "))
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}
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// TODO: Gate17 integration
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// tunnelInfo, err := AssignTunnelIP(fqdn)
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return rrCache
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}
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// checkRelation tries to find a relation between a process and a communication. This is for better out of the box experience and is _not_ meant to thwart intentional malware.
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func checkRelation(conn *network.Connection) (related bool, reason string) {
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if conn.Entity.Domain != "" {
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return false, ""
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}
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// don't check for unknown processes
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if conn.Process().Pid < 0 {
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return false, ""
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}
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pathElements := strings.Split(conn.Process().Path, string(filepath.Separator))
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// only look at the last two path segments
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if len(pathElements) > 2 {
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pathElements = pathElements[len(pathElements)-2:]
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}
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domainElements := strings.Split(conn.Entity.Domain, ".")
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var domainElement string
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var processElement string
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matchLoop:
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for _, domainElement = range domainElements {
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for _, pathElement := range pathElements {
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if levenshtein.Match(domainElement, pathElement, nil) > 0.5 {
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related = true
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processElement = pathElement
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break matchLoop
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}
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}
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if levenshtein.Match(domainElement, conn.Process().Name, nil) > 0.5 {
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related = true
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processElement = conn.Process().Name
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break matchLoop
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}
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if levenshtein.Match(domainElement, conn.Process().ExecName, nil) > 0.5 {
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related = true
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processElement = conn.Process().ExecName
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break matchLoop
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}
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}
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if related {
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reason = fmt.Sprintf("domain is related to process: %s is related to %s", domainElement, processElement)
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}
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return related, reason
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}
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