refactor of proc reading code

policy.go

@@ -163,7 +163,7 @@ func (fw *Firewall) filterPacket(pkt *nfqueue.Packet) {
 		fw.dns.processDNS(pkt)
 		return
 	}
-	pinfo := proc.FindProcessForPacket(pkt)
+	pinfo := findProcessForPacket(pkt)
 	if pinfo == nil {
 		log.Warning("No proc found for %s", printPacket(pkt, fw.dns.Lookup(pkt.Dst)))
 		pkt.Accept()
@@ -180,6 +180,20 @@ func (fw *Firewall) filterPacket(pkt *nfqueue.Packet) {
 	policy.processPacket(pkt, pinfo)
 }
 
+func findProcessForPacket(pkt *nfqueue.Packet) *proc.ProcInfo {
+	proto := ""
+	switch pkt.Protocol {
+	case nfqueue.TCP:
+		proto = "tcp"
+	case nfqueue.UDP:
+		proto = "udp"
+	default:
+		log.Warning("Packet has unknown protocol: %d", pkt.Protocol)
+		return nil
+	}
+	return proc.LookupSocketProcess(proto, pkt.SrcPort, pkt.Dst, pkt.DstPort)
+}
+
 func basicAllowPacket(pkt *nfqueue.Packet) bool {
 	return pkt.Dst.IsLoopback() ||
 		pkt.Dst.IsLinkLocalMulticast() ||

proc/proc.go

@@ -19,101 +19,24 @@ func SetLogger(logger *logging.Logger) {
 	log = logger
 }
 
-type socketAddr struct {
+var pcache = &pidCache{}
-	ip   net.IP
-	port uint16
-}
-
-func (sa socketAddr) String() string {
-	return fmt.Sprintf("%v:%d", sa.ip, sa.port)
-}
 
-type socketStatus struct {
+func LookupSocketProcess(proto string, srcPort uint16, dstAddr net.IP, dstPort uint16) *ProcInfo {
-	local  socketAddr
+	ss := findSocket(proto, srcPort, dstAddr, dstPort)
-	remote socketAddr
+	if ss == nil {
-	uid    int
+		return nil
-	inode  uint64
+	}
-	pid    int
+	return pcache.lookup(ss.inode)
-	// XXX debugging
-	line string
-}
-
-func (ss *socketStatus) String() string {
-	return fmt.Sprintf("%s -> %s uid=%d inode=%d pid=%d", ss.local, ss.remote, ss.uid, ss.inode, ss.pid)
 }
 
 type ConnectionInfo struct {
-	proc *ProcInfo
+	pinfo *ProcInfo
 	local *socketAddr
 	remote *socketAddr
 }
 
 func (ci *ConnectionInfo) String() string {
-	return fmt.Sprintf("%v %s %s", ci.proc, ci.local, ci.remote)
+	return fmt.Sprintf("%v %s %s", ci.pinfo, ci.local, ci.remote)
-}
-
-func FindProcessForPacket(pkt *nfqueue.Packet) *ProcInfo {
-	ss := getSocketForPacket(pkt)
-	if ss == nil {
-		return nil
-	}
-	return findProcessForSocket(ss)
-}
-func findProcessForSocket(ss *socketStatus) *ProcInfo {
-
-	exePath, err := os.Readlink(fmt.Sprintf("/proc/%d/exe", ss.pid))
-	if err != nil {
-		log.Warning("Error reading exe link for pid %d: %v", ss.pid, err)
-		return nil
-	}
-	bs, err := ioutil.ReadFile(fmt.Sprintf("/proc/%d/cmdline", ss.pid))
-	if err != nil {
-		log.Warning("Error reading cmdline for pid %d: %v", ss.pid, err)
-		return nil
-	}
-	for i, b := range bs {
-		if b == 0 {
-			bs[i] = byte(' ')
-		}
-	}
-
-	finfo, err := os.Stat(fmt.Sprintf("/proc/%d", ss.pid))
-	if err != nil {
-		log.Warning("Could not stat /proc/%d: %v", ss.pid, err)
-		return nil
-	}
-	finfo.Sys()
-	return &ProcInfo{
-		Pid:     ss.pid,
-		Uid:     ss.uid,
-		ExePath: exePath,
-		CmdLine: string(bs),
-	}
-}
-
-func getSocketLinesForPacket(pkt *nfqueue.Packet) []string {
-	if pkt.Protocol == nfqueue.TCP {
-		return getSocketLines("tcp")
-	} else if pkt.Protocol == nfqueue.UDP {
-		return getSocketLines("udp")
-	} else {
-		log.Warning("Cannot lookup socket for protocol %s", pkt.Protocol)
-		return nil
-	}
-}
-
-func getSocketLines(proto string) []string {
-	path := fmt.Sprintf("/proc/net/%s", proto)
-	data, err := ioutil.ReadFile(path)
-	if err != nil {
-		log.Warning("Error reading %s: %v", path, err)
-		return nil
-	}
-	lines := strings.Split(string(data), "\n")
-	if len(lines) > 0 {
-		lines = lines[1:]
-	}
-	return lines
 }
 
 func (sa *socketAddr) parse(s string) error {
@@ -134,29 +57,6 @@ func (sa *socketAddr) parse(s string) error {
 	return nil
 }
 
-func (ss *socketStatus) parseLine(line string) error {
-	fs := strings.Fields(line)
-	if len(fs) < 10 {
-		return errors.New("insufficient fields")
-	}
-	if err := ss.local.parse(fs[1]); err != nil {
-		return err
-	}
-	if err := ss.remote.parse(fs[2]); err != nil {
-		return err
-	}
-	uid, err := strconv.ParseUint(fs[7], 10, 32)
-	if err != nil {
-		return err
-	}
-	ss.uid = int(uid)
-	inode, err := strconv.ParseUint(fs[9], 10, 64)
-	if err != nil {
-		return err
-	}
-	ss.inode = inode
-	return nil
-}
 
 func printPacket(pkt *nfqueue.Packet) string {
 	proto := func() string {
@@ -172,38 +72,6 @@ func printPacket(pkt *nfqueue.Packet) string {
 	return fmt.Sprintf("(%s %s:%d --> %s:%d)", proto, pkt.Src, pkt.SrcPort, pkt.Dst.String(), pkt.DstPort)
 }
 
-func getSocketForPacket(pkt *nfqueue.Packet) *socketStatus {
-	ss := findSocket(pkt)
-	if ss == nil {
-		return nil
-	}
-	pid := findPidForInode(ss.inode)
-	if pid > 0 {
-		ss.pid = pid
-		return ss
-	}
-	log.Info("Unable to find socket link socket:[%d] %s", ss.inode, printPacket(pkt))
-	log.Info("Line was %s", ss.line)
-	return nil
-}
-
-func findSocket(pkt *nfqueue.Packet) *socketStatus {
-	var status socketStatus
-	for _, line := range getSocketLinesForPacket(pkt) {
-		if len(line) == 0 {
-			continue
-		}
-		if err := status.parseLine(line); err != nil {
-			log.Warning("Unable to parse line [%s]: %v", line, err)
-		} else if status.remote.ip.Equal(pkt.Dst) && status.remote.port == pkt.DstPort && status.local.ip.Equal(pkt.Src) && status.local.port == pkt.SrcPort {
-			status.line = line
-			return &status
-		}
-	}
-	log.Info("Failed to find socket for packet: %s", printPacket(pkt))
-	return nil
-}
-
 func ParseIp(ip string) (net.IP, error) {
 	var result net.IP
 	dst, err := hex.DecodeString(ip)
@@ -227,48 +95,6 @@ func ParsePort(port string) (uint16, error) {
 	return uint16(p64), nil
 }
 
-func findPidForInode(inode uint64) int {
-	search := fmt.Sprintf("socket:[%d]", inode)
-	for _, pid := range getAllPids() {
-		if matchesSocketLink(pid, search) {
-			return pid
-		}
-	}
-	return -1
-}
-
-func matchesSocketLink(pid int, search string) bool {
-	paths, _ := filepath.Glob(fmt.Sprintf("/proc/%d/fd/*", pid))
-	for _, p := range paths {
-		link, err := os.Readlink(p)
-		if err == nil && link == search {
-			return true
-		}
-	}
-	return false
-}
-
-func getAllPids() []int {
-	var pids []int
-	d, err := os.Open("/proc")
-	if err != nil {
-		log.Warning("Error opening /proc: %v", err)
-		return nil
-	}
-	defer d.Close()
-	names, err := d.Readdirnames(0)
-	if err != nil {
-		log.Warning("Error reading directory names from /proc: %v", err)
-		return nil
-	}
-	for _, n := range names {
-		if pid, err := strconv.ParseUint(n, 10, 32); err == nil {
-			pids = append(pids, int(pid))
-		}
-	}
-	return pids
-}
-
 func getConnections() ([]*ConnectionInfo, error) {
 	conns,err := readConntrack()
 	if err != nil {
@@ -288,12 +114,14 @@ func resolveProcinfo(conns []*ConnectionInfo) {
 		if err := ss.parseLine(line); err != nil {
 			log.Warning("Unable to parse line [%s]: %v", line, err)
 		} else {
+			/*
 			pid := findPidForInode(ss.inode)
 			if pid > 0 {
 				ss.pid = pid
 				fmt.Println("Socket", ss)
 				sockets = append(sockets, ss)
 			}
+			*/
 		}
 	}
 	for _,ci := range conns {
@@ -301,9 +129,9 @@ func resolveProcinfo(conns []*ConnectionInfo) {
 		if ss == nil {
 			continue
 		}
-		proc := findProcessForSocket(ss)
+		pinfo := pcache.lookup(ss.inode)
-		if proc != nil {
+		if pinfo != nil {
-			ci.proc = proc
+			ci.pinfo = pinfo
 		}
 	}
 }

proc/proc_pid.go

@@ -7,6 +7,8 @@ import (
 	"strings"
 	"path"
 	"io/ioutil"
+	"sync"
+	"syscall"
 )
 
 
@@ -18,24 +20,38 @@ type ProcInfo struct {
 	CmdLine string
 }
 
-var cacheMap = make(map[uint64]*ProcInfo)
+type pidCache struct {
+	cacheMap map[uint64]*ProcInfo
+	lock sync.Mutex
+}
 
-func pidCacheLookup(inode uint64) *ProcInfo {
+func (pc *pidCache) lookup(inode uint64) *ProcInfo {
-	pi,ok := cacheMap[inode]
+	pc.lock.Lock()
-	if ok {
+	defer pc.lock.Unlock()
+	pi,ok := pc.cacheMap[inode]
+	if ok && pi.loadProcessInfo() {
+		return pi
+	}
+	pc.cacheMap = loadCache()
+	pi,ok = pc.cacheMap[inode]
+	if ok && pi.loadProcessInfo() {
 		return pi
 	}
-	pidCacheReload()
+	return nil
-	return cacheMap[inode]
 }
 
-func pidCacheReload() {
+func loadCache() map[uint64]*ProcInfo {
+	cmap := make(map[uint64]*ProcInfo)
 	for _, n := range readdir("/proc") {
 		pid := toPid(n)
 		if pid != 0 {
-			scrapePid(pid)
+			pinfo := &ProcInfo{Pid: pid}
+			for _,inode := range inodesFromPid(pid) {
+				cmap[inode] = pinfo
+			}
 		}
 	}
+	return cmap
 }
 
 func toPid(name string) int {
@@ -54,36 +70,34 @@ func toPid(name string) int {
 	return (int)(pid)
 }
 
-func scrapePid(pid int) {
+func inodesFromPid(pid int) []uint64 {
+	var inodes []uint64
 	fdpath := fmt.Sprintf("/proc/%d/fd", pid)
 	for _, n := range readdir(fdpath) {
 		if link, err := os.Readlink(path.Join(fdpath, n)); err != nil {
+			if !os.IsNotExist(err) {
 				log.Warning("Error reading link %s: %v", n, err)
+			}
 		} else {
-			extractSocket(link, pid)
+			if inode := extractSocket(link); inode > 0 {
+				inodes = append(inodes, inode)
 			}
 		}
+	}
+	return inodes
 }
 
-func extractSocket(name string, pid int) {
+func extractSocket(name string) uint64 {
 	if !strings.HasPrefix(name, "socket:[") || !strings.HasSuffix(name, "]") {
-		return
+		return 0
 	}
 	val := name[8:len(name)-1]
 	inode,err := strconv.ParseUint(val, 10, 64)
 	if err != nil {
 		log.Warning("Error parsing inode value from %s: %v", name, err)
-		return
+		return 0
-	}
-	cacheAddPid(inode, pid)
-}
-
-func cacheAddPid(inode uint64, pid int) {
-	pi,ok := cacheMap[inode]
-	if ok && pi.Pid == pid {
-		return
 	}
-	cacheMap[inode] = &ProcInfo{ Pid: pid }
+	return inode
 }
 
 func readdir(dir string) []string {
@@ -127,7 +141,8 @@ func (pi *ProcInfo) loadProcessInfo() bool {
 		log.Warning("Could not stat /proc/%d: %v", pi.Pid, err)
 		return false
 	}
-	finfo.Sys()
+	sys := finfo.Sys().(*syscall.Stat_t)
+	pi.Uid = int(sys.Uid)
 	pi.ExePath = exePath
 	pi.CmdLine = string(bs)
 	pi.loaded = true

proc/socket.go

@@ -0,0 +1,95 @@
+package proc
+import (
+	"net"
+	"fmt"
+	"io/ioutil"
+	"strings"
+	"errors"
+	"strconv"
+)
+
+type socketAddr struct {
+	ip net.IP
+	port uint16
+}
+
+func (sa socketAddr) String() string {
+	return fmt.Sprintf("%v:%d", sa.ip, sa.port)
+}
+
+type socketStatus struct {
+	local socketAddr
+	remote socketAddr
+	uid int
+	inode uint64
+	line string
+}
+
+func (ss *socketStatus) String() string {
+	return fmt.Sprintf("%s -> %s uid=%d inode=%d", ss.local, ss.remote, ss.uid, ss.inode)
+}
+
+func findUDPSocket(srcPort uint16, dstAddr net.IP, dstPort uint16) *socketStatus {
+	return findSocket("udp", srcPort, dstAddr, dstPort)
+}
+
+func findTCPSocket(srcPort uint16, dstAddr net.IP, dstPort uint16) *socketStatus {
+	return findSocket("tcp", srcPort, dstAddr, dstPort)
+}
+
+func findSocket(proto string, srcPort uint16, dstAddr net.IP, dstPort uint16) *socketStatus {
+	var ss socketStatus
+	for _,line := range getSocketLines(proto) {
+		if len(line) == 0 {
+			continue
+		}
+		if err := ss.parseLine(line); err != nil {
+			log.Warning("Unable to parse line from /proc/net/%s [%s]: %v", proto, line, err)
+			continue
+		}
+		if ss.remote.port == dstPort && ss.remote.ip.Equal(dstAddr) && ss.local.port == srcPort {
+			ss.line = line
+			return &ss
+		}
+	}
+	return nil
+}
+
+func (ss *socketStatus) parseLine(line string) error {
+	fs := strings.Fields(line)
+	if len(fs) < 10 {
+		return errors.New("insufficient fields")
+	}
+	if err := ss.local.parse(fs[1]); err != nil {
+		return err
+	}
+	if err := ss.remote.parse(fs[2]); err != nil {
+		return err
+	}
+	uid, err := strconv.ParseUint(fs[7], 10, 32)
+	if err != nil {
+		return err
+	}
+	ss.uid = int(uid)
+	inode, err := strconv.ParseUint(fs[9], 10, 64)
+	if err != nil {
+		return err
+	}
+	ss.inode = inode
+	return nil
+}
+
+
+func getSocketLines(proto string) []string {
+	path := fmt.Sprintf("/proc/net/%s", proto)
+	data, err := ioutil.ReadFile(path)
+	if err != nil {
+		log.Warning("Error reading %s: %v", path, err)
+		return nil
+	}
+	lines := strings.Split(string(data), "\n")
+	if len(lines) > 0 {
+		lines = lines[1:]
+	}
+	return lines
+}