mirror of https://gogs.blitter.com/RLabs/xs
854 lines
29 KiB
Go
Executable File
854 lines
29 KiB
Go
Executable File
// xsd server
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//
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// Copyright (c) 2017-2020 Russell Magee
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// Licensed under the terms of the MIT license (see LICENSE.mit in this
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// distribution)
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//
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// golang implementation by Russ Magee (rmagee_at_gmail.com)
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package main
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import (
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"bytes"
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"crypto/rand"
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"encoding/binary"
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"encoding/hex"
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"errors"
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"flag"
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"fmt"
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"io"
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"io/ioutil"
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"log"
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"os"
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"os/exec"
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"os/signal"
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"os/user"
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"path"
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"strings"
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"sync"
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"syscall"
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"time"
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"unsafe"
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"blitter.com/go/goutmp"
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xs "blitter.com/go/xs"
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"blitter.com/go/xs/logger"
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"blitter.com/go/xs/xsnet"
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"github.com/creack/pty"
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)
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var (
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version string
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gitCommit string // set in -ldflags by build
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useSysLogin bool
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kcpMode string // set to a valid KCP BlockCrypt alg tag to use rather than TCP
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// Log - syslog output (with no -d)
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Log *logger.Writer
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)
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func ioctl(fd, request, argp uintptr) error {
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if _, _, e := syscall.Syscall6(syscall.SYS_IOCTL, fd, request, argp, 0, 0, 0); e != 0 {
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return e
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}
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return nil
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}
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func ptsName(fd uintptr) (string, error) {
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var n uintptr
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err := ioctl(fd, syscall.TIOCGPTN, uintptr(unsafe.Pointer(&n)))
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if err != nil {
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return "", err
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}
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return fmt.Sprintf("/dev/pts/%d", n), nil
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}
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/* -------------------------------------------------------------- */
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// Perform a client->server copy
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func runClientToServerCopyAs(who, ttype string, conn *xsnet.Conn, fpath string, chaffing bool) (exitStatus uint32, err error) {
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u, _ := user.Lookup(who) // nolint: gosec
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var uid, gid uint32
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fmt.Sscanf(u.Uid, "%d", &uid) // nolint: gosec,errcheck
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fmt.Sscanf(u.Gid, "%d", &gid) // nolint: gosec,errcheck
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log.Println("uid:", uid, "gid:", gid)
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// Need to clear server's env and set key vars of the
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// target user. This isn't perfect (TERM doesn't seem to
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// work 100%; ANSI/xterm colour isn't working even
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// if we set "xterm" or "ansi" here; and line count
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// reported by 'stty -a' defaults to 24 regardless
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// of client shell window used to run client.
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// Investigate -- rlm 2018-01-26)
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os.Clearenv()
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os.Setenv("HOME", u.HomeDir) // nolint: gosec,errcheck
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os.Setenv("TERM", ttype) // nolint: gosec,errcheck
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os.Setenv("XS_SESSION", "1") // nolint: gosec,errcheck
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var c *exec.Cmd
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cmdName := xs.GetTool("tar")
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var destDir string
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if path.IsAbs(fpath) {
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destDir = fpath
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} else {
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destDir = path.Join(u.HomeDir, fpath)
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}
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cmdArgs := []string{"-xz", "-C", destDir}
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// NOTE the lack of quotes around --xform option's sed expression.
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// When args are passed in exec() format, no quoting is required
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// (as this isn't input from a shell) (right? -rlm 20180823)
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//cmdArgs := []string{"-x", "-C", destDir, `--xform=s#.*/\(.*\)#\1#`}
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fmt.Println(cmdName, cmdArgs)
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c = exec.Command(cmdName, cmdArgs...) // nolint: gosec
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c.Dir = destDir
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//If os.Clearenv() isn't called by server above these will be seen in the
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//client's session env.
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//c.Env = []string{"HOME=" + u.HomeDir, "SUDO_GID=", "SUDO_UID=", "SUDO_USER=", "SUDO_COMMAND=", "MAIL=", "LOGNAME="+who}
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//c.Dir = u.HomeDir
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c.SysProcAttr = &syscall.SysProcAttr{}
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c.SysProcAttr.Credential = &syscall.Credential{Uid: uid, Gid: gid}
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c.Stdin = conn
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c.Stdout = os.Stdout
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c.Stderr = os.Stderr
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if chaffing {
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conn.EnableChaff()
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}
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defer conn.DisableChaff()
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defer conn.ShutdownChaff()
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// Start the command (no pty)
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log.Printf("[%v %v]\n", cmdName, cmdArgs)
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err = c.Start() // returns immediately
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/////////////
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// NOTE: There is, apparently, a bug in Go stdlib here. Start()
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// can actually return immediately, on a command which *does*
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// start but exits quickly, with c.Wait() error
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// "c.Wait status: exec: not started".
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// As in this example, attempting a client->server copy to
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// a nonexistent remote dir (it's tar exiting right away, exitStatus
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// 2, stderr
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// /bin/tar -xz -C /home/someuser/nosuchdir
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// stderr: fork/exec /bin/tar: no such file or directory
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//
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// In this case, c.Wait() won't give us the real
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// exit status (is it lost?).
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/////////////
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if err != nil {
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log.Println("cmd exited immediately. Cannot get cmd.Wait().ExitStatus()")
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err = errors.New("cmd exited prematurely")
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//exitStatus = uint32(254)
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exitStatus = xsnet.CSEExecFail
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} else {
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if err := c.Wait(); err != nil {
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//fmt.Println("*** c.Wait() done ***")
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if exiterr, ok := err.(*exec.ExitError); ok {
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// The program has exited with an exit code != 0
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// This works on both Unix and Windows. Although package
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// syscall is generally platform dependent, WaitStatus is
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// defined for both Unix and Windows and in both cases has
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// an ExitStatus() method with the same signature.
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if status, ok := exiterr.Sys().(syscall.WaitStatus); ok {
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exitStatus = uint32(status.ExitStatus())
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//err = errors.New("cmd returned nonzero status")
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log.Printf("Exit Status: %d\n", exitStatus)
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}
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}
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}
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log.Println("*** client->server cp finished ***")
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}
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return
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}
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// Perform a server->client copy
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func runServerToClientCopyAs(who, ttype string, conn *xsnet.Conn, srcPath string, chaffing bool) (exitStatus uint32, err error) {
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u, err := user.Lookup(who)
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if err != nil {
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exitStatus = 1
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return
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}
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var uid, gid uint32
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_, _ = fmt.Sscanf(u.Uid, "%d", &uid) // nolint: gosec
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_, _ = fmt.Sscanf(u.Gid, "%d", &gid) // nolint: gosec
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log.Println("uid:", uid, "gid:", gid)
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// Need to clear server's env and set key vars of the
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// target user. This isn't perfect (TERM doesn't seem to
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// work 100%; ANSI/xterm colour isn't working even
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// if we set "xterm" or "ansi" here; and line count
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// reported by 'stty -a' defaults to 24 regardless
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// of client shell window used to run client.
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// Investigate -- rlm 2018-01-26)
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os.Clearenv()
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_ = os.Setenv("HOME", u.HomeDir) // nolint: gosec
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_ = os.Setenv("TERM", ttype) // nolint: gosec
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_ = os.Setenv("XS_SESSION", "1") // nolint: gosec
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var c *exec.Cmd
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cmdName := xs.GetTool("tar")
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if !path.IsAbs(srcPath) {
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srcPath = fmt.Sprintf("%s%c%s", u.HomeDir, os.PathSeparator, srcPath)
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}
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srcDir, srcBase := path.Split(srcPath)
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cmdArgs := []string{"-cz", "-C", srcDir, "-f", "-", srcBase}
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c = exec.Command(cmdName, cmdArgs...) // nolint: gosec
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//If os.Clearenv() isn't called by server above these will be seen in the
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//client's session env.
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//c.Env = []string{"HOME=" + u.HomeDir, "SUDO_GID=", "SUDO_UID=", "SUDO_USER=", "SUDO_COMMAND=", "MAIL=", "LOGNAME="+who}
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c.Dir = u.HomeDir
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c.SysProcAttr = &syscall.SysProcAttr{}
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c.SysProcAttr.Credential = &syscall.Credential{Uid: uid, Gid: gid}
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c.Stdout = conn
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// Stderr sinkholing (or buffering to something other than stdout)
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// is important. Any extraneous output to tarpipe messes up remote
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// side as it's expecting pure tar data.
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// (For example, if user specifies abs paths, tar outputs
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// "Removing leading '/' from path names")
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stdErrBuffer := new(bytes.Buffer)
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c.Stderr = stdErrBuffer
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//c.Stderr = nil
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if chaffing {
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conn.EnableChaff()
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}
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//defer conn.Close()
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defer conn.DisableChaff()
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defer conn.ShutdownChaff()
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// Start the command (no pty)
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log.Printf("[%v %v]\n", cmdName, cmdArgs)
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err = c.Start() // returns immediately
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if err != nil {
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log.Printf("Command finished with error: %v", err)
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return xsnet.CSEExecFail, err // !?
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}
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if err := c.Wait(); err != nil {
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//fmt.Println("*** c.Wait() done ***")
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if exiterr, ok := err.(*exec.ExitError); ok {
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// The program has exited with an exit code != 0
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// This works on both Unix and Windows. Although package
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// syscall is generally platform dependent, WaitStatus is
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// defined for both Unix and Windows and in both cases has
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// an ExitStatus() method with the same signature.
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if status, ok := exiterr.Sys().(syscall.WaitStatus); ok {
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exitStatus = uint32(status.ExitStatus())
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if len(stdErrBuffer.Bytes()) > 0 {
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log.Print(stdErrBuffer)
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}
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log.Printf("Exit Status: %d", exitStatus)
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}
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}
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}
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//fmt.Println("*** server->client cp finished ***")
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return
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}
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// Run a command (via default shell) as a specific user
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//
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// Uses ptys to support commands which expect a terminal.
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// nolint: gocyclo
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func runShellAs(who, hname, ttype, cmd string, interactive bool, conn *xsnet.Conn, chaffing bool) (exitStatus uint32, err error) {
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var wg sync.WaitGroup
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u, err := user.Lookup(who)
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if err != nil {
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exitStatus = 1
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return
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}
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var uid, gid uint32
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_, _ = fmt.Sscanf(u.Uid, "%d", &uid) // nolint: gosec
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_, _ = fmt.Sscanf(u.Gid, "%d", &gid) // nolint: gosec
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log.Println("uid:", uid, "gid:", gid)
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// Need to clear server's env and set key vars of the
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// target user. This isn't perfect (TERM doesn't seem to
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// work 100%; ANSI/xterm colour isn't working even
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// if we set "xterm" or "ansi" here; and line count
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// reported by 'stty -a' defaults to 24 regardless
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// of client shell window used to run client.
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// Investigate -- rlm 2018-01-26)
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os.Clearenv()
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_ = os.Setenv("HOME", u.HomeDir) // nolint: gosec
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_ = os.Setenv("TERM", ttype) // nolint: gosec
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_ = os.Setenv("XS_SESSION", "1") // nolint: gosec
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var c *exec.Cmd
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if interactive {
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if useSysLogin {
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// Use the server's login binary (post-auth, which
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// is still done via our own bcrypt file)
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//
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// Note login will drop privs to the intended user for us
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//
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// Things UNIX login does, like print the 'motd',
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// and use the shell specified by /etc/passwd, will be done
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// automagically, at the cost of another external tool
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// dependency.
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//
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c = exec.Command(xs.GetTool("login"), "-f", "-p", who) // nolint: gosec
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} else {
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// Using our separate login via local passwd file
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//
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// Note we must drop privs ourselves for the user shell
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//
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c = exec.Command(xs.GetTool("bash"), "-i", "-l") // nolint: gosec
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c.SysProcAttr = &syscall.SysProcAttr{}
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c.SysProcAttr.Credential = &syscall.Credential{Uid: uid, Gid: gid}
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}
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} else {
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c = exec.Command(xs.GetTool("bash"), "-c", cmd) // nolint: gosec
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c.SysProcAttr = &syscall.SysProcAttr{}
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c.SysProcAttr.Credential = &syscall.Credential{Uid: uid, Gid: gid}
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}
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//If os.Clearenv() isn't called by server above these will be seen in the
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//client's session env.
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//c.Env = []string{"HOME=" + u.HomeDir, "SUDO_GID=", "SUDO_UID=", "SUDO_USER=", "SUDO_COMMAND=", "MAIL=", "LOGNAME="+who}
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c.Dir = u.HomeDir
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// Start the command with a pty.
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ptmx, err := pty.Start(c) // returns immediately with ptmx file
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if err != nil {
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log.Println(err)
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return xsnet.CSEPtyExecFail, err
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}
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// Make sure to close the pty at the end.
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// #gv:s/label=\"runShellAs\$1\"/label=\"deferPtmxClose\"/
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defer func() {
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//logger.LogDebug(fmt.Sprintf("[Exited process was %d]", c.Process.Pid))
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_ = ptmx.Close()
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}() // nolint: gosec
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// get pty info for system accounting (who, lastlog)
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pts, pe := ptsName(ptmx.Fd())
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if pe != nil {
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return xsnet.CSEPtyGetNameFail, err
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}
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utmpx := goutmp.Put_utmp(who, pts, hname)
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defer func() { goutmp.Unput_utmp(utmpx) }()
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goutmp.Put_lastlog_entry("xs", who, pts, hname)
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log.Printf("[%s]\n", cmd)
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if err != nil {
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log.Printf("Command finished with error: %v", err)
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} else {
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// Watch for term resizes
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// #gv:s/label=\"runShellAs\$2\"/label=\"termResizeWatcher\"/
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go func() {
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for sz := range conn.WinCh {
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log.Printf("[Setting term size to: %v %v]\n", sz.Rows, sz.Cols)
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pty.Setsize(ptmx, &pty.Winsize{Rows: sz.Rows, Cols: sz.Cols}) // nolint: gosec,errcheck
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}
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log.Println("*** WinCh goroutine done ***")
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}()
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// Copy stdin to the pty.. (bgnd goroutine)
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// #gv:s/label=\"runShellAs\$3\"/label=\"stdinToPtyWorker\"/
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go func() {
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_, e := io.Copy(ptmx, conn)
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if e != nil {
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log.Println("** stdin->pty ended **:", e.Error())
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} else {
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log.Println("*** stdin->pty goroutine done ***")
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}
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}()
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if chaffing {
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conn.EnableChaff()
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}
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// #gv:s/label=\"runShellAs\$4\"/label=\"deferChaffShutdown\"/
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defer func() {
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conn.DisableChaff()
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conn.ShutdownChaff()
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}()
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// ..and the pty to stdout.
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// This may take some time exceeding that of the
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// actual command's lifetime, so the c.Wait() below
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// must synchronize with the completion of this goroutine
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// to ensure all stdout data gets to the client before
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// connection is closed.
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wg.Add(1)
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// #gv:s/label=\"runShellAs\$5\"/label=\"ptyToStdoutWorker\"/
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go func() {
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defer wg.Done()
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_, e := io.Copy(conn, ptmx)
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if e != nil {
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log.Println("** pty->stdout ended **:", e.Error())
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} else {
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// The above io.Copy() will exit when the command attached
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// to the pty exits
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log.Println("*** pty->stdout goroutine done ***")
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}
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}()
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if err := c.Wait(); err != nil {
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//fmt.Println("*** c.Wait() done ***")
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if exiterr, ok := err.(*exec.ExitError); ok {
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// The program has exited with an exit code != 0
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// This works on both Unix and Windows. Although package
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// syscall is generally platform dependent, WaitStatus is
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// defined for both Unix and Windows and in both cases has
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// an ExitStatus() method with the same signature.
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if status, ok := exiterr.Sys().(syscall.WaitStatus); ok {
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exitStatus = uint32(status.ExitStatus())
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log.Printf("Exit Status: %d", exitStatus)
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}
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}
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conn.SetStatus(xsnet.CSOType(exitStatus))
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} else {
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logger.LogDebug("*** Main proc has exited. ***")
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// Background jobs still may be running; close the
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// pty anyway, so the client can return before
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// wg.Wait() below completes (Issue #18)
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if interactive {
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_ = ptmx.Close()
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}
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}
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wg.Wait() // Wait on pty->stdout completion to client
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}
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return
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}
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// GenAuthToken generates a pseudorandom auth token for a specific
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// user from a specific host to allow non-interactive logins.
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func GenAuthToken(who string, connhost string) string {
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//hname, e := os.Hostname()
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//if e != nil {
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// hname = "#badhost#"
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//}
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hname := connhost
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token := make([]byte, 64)
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_, _ = rand.Read(token) // nolint: gosec
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return fmt.Sprintf("%s:%s:%s", hname, who, hex.EncodeToString(token))
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}
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var (
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aKEXAlgs allowedKEXAlgs
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aCipherAlgs allowedCipherAlgs
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aHMACAlgs allowedHMACAlgs
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)
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type allowedKEXAlgs []string // TODO
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type allowedCipherAlgs []string // TODO
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type allowedHMACAlgs []string // TODO
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func (a allowedKEXAlgs) allowed(k xsnet.KEXAlg) bool {
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for i := 0; i < len(a); i++ {
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if a[i] == "KEX_all" || a[i] == k.String() {
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return true
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}
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}
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return false
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}
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func (a *allowedKEXAlgs) String() string {
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return fmt.Sprintf("allowedKEXAlgs: %v", *a)
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}
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func (a *allowedKEXAlgs) Set(value string) error {
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*a = append(*a, strings.TrimSpace(value))
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return nil
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}
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func (a allowedCipherAlgs) allowed(c xsnet.CSCipherAlg) bool {
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for i := 0; i < len(a); i++ {
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if a[i] == "C_all" || a[i] == c.String() {
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return true
|
|
}
|
|
}
|
|
return false
|
|
}
|
|
|
|
func (a *allowedCipherAlgs) String() string {
|
|
return fmt.Sprintf("allowedCipherAlgs: %v", *a)
|
|
}
|
|
|
|
func (a *allowedCipherAlgs) Set(value string) error {
|
|
*a = append(*a, strings.TrimSpace(value))
|
|
return nil
|
|
}
|
|
|
|
func (a allowedHMACAlgs) allowed(h xsnet.CSHmacAlg) bool {
|
|
for i := 0; i < len(a); i++ {
|
|
if a[i] == "H_all" || a[i] == h.String() {
|
|
return true
|
|
}
|
|
}
|
|
return false
|
|
}
|
|
|
|
func (a *allowedHMACAlgs) String() string {
|
|
return fmt.Sprintf("allowedHMACAlgs: %v", *a)
|
|
}
|
|
|
|
func (a *allowedHMACAlgs) Set(value string) error {
|
|
*a = append(*a, strings.TrimSpace(value))
|
|
return nil
|
|
}
|
|
|
|
// Main server that listens and spawns goroutines for each
|
|
// connecting client to serve interactive or file copy sessions
|
|
// and any requested tunnels.
|
|
// Note that this server does not do UNIX forks of itself to give
|
|
// each client its own separate manager process, so if the main
|
|
// daemon dies, all clients will be rudely disconnected.
|
|
// Consider this when planning to restart or upgrade in-place an installation.
|
|
// TODO: reduce gocyclo
|
|
func main() {
|
|
var vopt bool
|
|
var chaffEnabled bool
|
|
var chaffFreqMin uint
|
|
var chaffFreqMax uint
|
|
var chaffBytesMax uint
|
|
var dbg bool
|
|
var laddr string
|
|
|
|
var useSystemPasswd bool
|
|
|
|
flag.BoolVar(&vopt, "v", false, "show version")
|
|
flag.StringVar(&laddr, "l", ":2000", "interface[:port] to listen")
|
|
flag.StringVar(&kcpMode, "K", "unused", `set to one of ["KCP_NONE","KCP_AES", "KCP_BLOWFISH", "KCP_CAST5", "KCP_SM4", "KCP_SALSA20", "KCP_SIMPLEXOR", "KCP_TEA", "KCP_3DES", "KCP_TWOFISH", "KCP_XTEA"] to use KCP (github.com/xtaci/kcp-go) reliable UDP instead of TCP`)
|
|
flag.BoolVar(&useSysLogin, "L", false, "use system login")
|
|
flag.BoolVar(&chaffEnabled, "e", true, "enable chaff pkts")
|
|
flag.UintVar(&chaffFreqMin, "f", 100, "chaff pkt freq min (msecs)")
|
|
flag.UintVar(&chaffFreqMax, "F", 5000, "chaff pkt freq max (msecs)")
|
|
flag.UintVar(&chaffBytesMax, "B", 64, "chaff pkt size max (bytes)")
|
|
flag.BoolVar(&useSystemPasswd, "s", true, "use system shadow passwds")
|
|
flag.BoolVar(&dbg, "d", false, "debug logging")
|
|
|
|
flag.Var(&aKEXAlgs, "aK", `List of allowed KEX algs (eg. 'KEXAlgA KEXAlgB ... KEXAlgN') (default allow all)`)
|
|
flag.Var(&aCipherAlgs, "aC", `List of allowed ciphers (eg. 'CipherAlgA CipherAlgB ... CipherAlgN') (default allow all)`)
|
|
flag.Var(&aHMACAlgs, "aH", `List of allowed HMACs (eg. 'HMACAlgA HMACAlgB ... HMACAlgN') (default allow all)`)
|
|
|
|
flag.Parse()
|
|
|
|
if vopt {
|
|
fmt.Printf("version %s (%s)\n", version, gitCommit)
|
|
os.Exit(0)
|
|
}
|
|
|
|
{
|
|
me, e := user.Current()
|
|
if e != nil || me.Uid != "0" {
|
|
log.Fatal("Must run as root.")
|
|
}
|
|
}
|
|
|
|
// Enforce some sane min/max vals on chaff flags
|
|
if chaffFreqMin < 2 {
|
|
chaffFreqMin = 2
|
|
}
|
|
if chaffFreqMax == 0 {
|
|
chaffFreqMax = chaffFreqMin + 1
|
|
}
|
|
if chaffBytesMax == 0 || chaffBytesMax > 4096 {
|
|
chaffBytesMax = 64
|
|
}
|
|
|
|
Log, _ = logger.New(logger.LOG_DAEMON|logger.LOG_DEBUG|logger.LOG_NOTICE|logger.LOG_ERR, "xsd") // nolint: gosec
|
|
xsnet.Init(dbg, "xsd", logger.LOG_DAEMON|logger.LOG_DEBUG|logger.LOG_NOTICE|logger.LOG_ERR)
|
|
if dbg {
|
|
log.SetOutput(Log)
|
|
} else {
|
|
log.SetOutput(ioutil.Discard)
|
|
}
|
|
|
|
// Set up allowed algs, if specified (default allow all)
|
|
if len(aKEXAlgs) == 0 {
|
|
aKEXAlgs = []string{"KEX_all"}
|
|
}
|
|
logger.LogNotice(fmt.Sprintf("Allowed KEXAlgs: %v\n", aKEXAlgs)) // nolint: gosec,errcheck
|
|
|
|
if len(aCipherAlgs) == 0 {
|
|
aCipherAlgs = []string{"C_all"}
|
|
}
|
|
logger.LogNotice(fmt.Sprintf("Allowed CipherAlgs: %v\n", aCipherAlgs)) // nolint: gosec,errcheck
|
|
|
|
if len(aHMACAlgs) == 0 {
|
|
aHMACAlgs = []string{"H_all"}
|
|
}
|
|
logger.LogNotice(fmt.Sprintf("Allowed HMACAlgs: %v\n", aHMACAlgs)) // nolint: gosec,errcheck
|
|
|
|
// Set up handler for daemon signalling
|
|
exitCh := make(chan os.Signal, 1)
|
|
signal.Notify(exitCh, os.Signal(syscall.SIGTERM), os.Signal(syscall.SIGINT), os.Signal(syscall.SIGHUP), os.Signal(syscall.SIGUSR1), os.Signal(syscall.SIGUSR2))
|
|
go func() {
|
|
for {
|
|
sig := <-exitCh
|
|
switch sig.String() {
|
|
case "terminated":
|
|
logger.LogNotice(fmt.Sprintf("[Got signal: %s]", sig)) // nolint: gosec,errcheck
|
|
signal.Reset()
|
|
syscall.Kill(0, syscall.SIGTERM) // nolint: gosec,errcheck
|
|
case "interrupt":
|
|
logger.LogNotice(fmt.Sprintf("[Got signal: %s]", sig)) // nolint: gosec,errcheck
|
|
signal.Reset()
|
|
syscall.Kill(0, syscall.SIGINT) // nolint: gosec,errcheck
|
|
case "hangup":
|
|
logger.LogNotice(fmt.Sprintf("[Got signal: %s - nop]", sig)) // nolint:gosec,errcheck
|
|
default:
|
|
logger.LogNotice(fmt.Sprintf("[Got signal: %s - ignored]", sig)) // nolint: gosec,errcheck
|
|
}
|
|
}
|
|
}()
|
|
|
|
proto := "tcp"
|
|
if kcpMode != "unused" {
|
|
proto = "kcp"
|
|
}
|
|
l, err := xsnet.Listen(proto, laddr, kcpMode)
|
|
if err != nil {
|
|
log.Fatal(err)
|
|
}
|
|
defer l.Close() // nolint: errcheck
|
|
|
|
log.Println("Serving on", laddr)
|
|
for {
|
|
// Wait for a connection.
|
|
// Then check if client-proposed algs are allowed
|
|
conn, err := l.Accept()
|
|
if err != nil {
|
|
log.Printf("Accept() got error(%v), hanging up.\n", err)
|
|
} else if !aKEXAlgs.allowed(conn.KEX()) {
|
|
log.Printf("Accept() rejected for banned KEX alg %d, hanging up.\n", conn.KEX())
|
|
conn.SetStatus(xsnet.CSEKEXAlgDenied)
|
|
conn.Close()
|
|
} else if !aCipherAlgs.allowed(conn.CAlg()) {
|
|
log.Printf("Accept() rejected for banned Cipher alg %d, hanging up.\n", conn.CAlg())
|
|
conn.SetStatus(xsnet.CSECipherAlgDenied)
|
|
conn.Close()
|
|
} else if !aHMACAlgs.allowed(conn.HAlg()) {
|
|
log.Printf("Accept() rejected for banned HMAC alg %d, hanging up.\n", conn.HAlg())
|
|
conn.SetStatus(xsnet.CSEHMACAlgDenied)
|
|
conn.Close()
|
|
} else {
|
|
log.Println("Accepted client")
|
|
|
|
// Set up chaffing to client
|
|
// Will only start when runShellAs() is called
|
|
// after stdin/stdout are hooked up
|
|
conn.SetupChaff(chaffFreqMin, chaffFreqMax, chaffBytesMax) // configure server->client chaffing
|
|
|
|
// Handle the connection in a new goroutine.
|
|
// The loop then returns to accepting, so that
|
|
// multiple connections may be served concurrently.
|
|
go func(hc *xsnet.Conn) (e error) {
|
|
defer hc.Close() // nolint: errcheck
|
|
|
|
// Start login timeout here and disconnect if user/pass phase stalls
|
|
loginTimeout := time.AfterFunc(30*time.Second, func() {
|
|
logger.LogNotice(fmt.Sprintln("Login timed out")) // nolint: errcheck,gosec
|
|
hc.Write([]byte{0}) // nolint: gosec,errcheck
|
|
hc.Close()
|
|
})
|
|
|
|
//We use io.ReadFull() here to guarantee we consume
|
|
//just the data we want for the xs.Session, and no more.
|
|
//Otherwise data will be sitting in the channel that isn't
|
|
//passed down to the command handlers.
|
|
var rec xs.Session
|
|
var len1, len2, len3, len4, len5, len6 uint32
|
|
|
|
n, err := fmt.Fscanf(hc, "%d %d %d %d %d %d\n", &len1, &len2, &len3, &len4, &len5, &len6)
|
|
log.Printf("xs.Session read:%d %d %d %d %d %d\n", len1, len2, len3, len4, len5, len6)
|
|
|
|
if err != nil || n < 6 {
|
|
log.Println("[Bad xs.Session fmt]")
|
|
return err
|
|
}
|
|
|
|
tmp := make([]byte, len1)
|
|
_, err = io.ReadFull(hc, tmp)
|
|
if err != nil {
|
|
log.Println("[Bad xs.Session.Op]")
|
|
return err
|
|
}
|
|
rec.SetOp(tmp)
|
|
|
|
tmp = make([]byte, len2)
|
|
_, err = io.ReadFull(hc, tmp)
|
|
if err != nil {
|
|
log.Println("[Bad xs.Session.Who]")
|
|
return err
|
|
}
|
|
rec.SetWho(tmp)
|
|
|
|
tmp = make([]byte, len3)
|
|
_, err = io.ReadFull(hc, tmp)
|
|
if err != nil {
|
|
log.Println("[Bad xs.Session.ConnHost]")
|
|
return err
|
|
}
|
|
rec.SetConnHost(tmp)
|
|
|
|
tmp = make([]byte, len4)
|
|
_, err = io.ReadFull(hc, tmp)
|
|
if err != nil {
|
|
log.Println("[Bad xs.Session.TermType]")
|
|
return err
|
|
}
|
|
rec.SetTermType(tmp)
|
|
|
|
tmp = make([]byte, len5)
|
|
_, err = io.ReadFull(hc, tmp)
|
|
if err != nil {
|
|
log.Println("[Bad xs.Session.Cmd]")
|
|
return err
|
|
}
|
|
rec.SetCmd(tmp)
|
|
|
|
tmp = make([]byte, len6)
|
|
_, err = io.ReadFull(hc, tmp)
|
|
if err != nil {
|
|
log.Println("[Bad xs.Session.AuthCookie]")
|
|
return err
|
|
}
|
|
rec.SetAuthCookie(tmp)
|
|
|
|
log.Printf("[xs.Session: op:%c who:%s connhost:%s cmd:%s auth:****]\n",
|
|
rec.Op()[0], string(rec.Who()), string(rec.ConnHost()), string(rec.Cmd()))
|
|
|
|
var valid bool
|
|
var allowedCmds string // Currently unused
|
|
if xs.AuthUserByToken(xs.NewAuthCtx(), string(rec.Who()), string(rec.ConnHost()), string(rec.AuthCookie(true))) {
|
|
valid = true
|
|
} else {
|
|
if useSystemPasswd {
|
|
//var passErr error
|
|
valid, _ /*passErr*/ = xs.VerifyPass(xs.NewAuthCtx(), string(rec.Who()), string(rec.AuthCookie(true)))
|
|
} else {
|
|
valid, allowedCmds = xs.AuthUserByPasswd(xs.NewAuthCtx(), string(rec.Who()), string(rec.AuthCookie(true)), "/etc/xs.passwd")
|
|
}
|
|
}
|
|
|
|
_ = loginTimeout.Stop()
|
|
// Security scrub
|
|
rec.ClearAuthCookie()
|
|
|
|
// Tell client if auth was valid
|
|
if valid {
|
|
hc.Write([]byte{1}) // nolint: gosec,errcheck
|
|
} else {
|
|
logger.LogNotice(fmt.Sprintln("Invalid user", string(rec.Who()))) // nolint: errcheck,gosec
|
|
hc.Write([]byte{0}) // nolint: gosec,errcheck
|
|
return
|
|
}
|
|
|
|
log.Printf("[allowedCmds:%s]\n", allowedCmds)
|
|
|
|
if rec.Op()[0] == 'A' {
|
|
// Generate automated login token
|
|
addr := hc.RemoteAddr()
|
|
hname := goutmp.GetHost(addr.String())
|
|
logger.LogNotice(fmt.Sprintf("[Generating autologin token for [%s@%s]]\n", rec.Who(), hname)) // nolint: gosec,errcheck
|
|
token := GenAuthToken(string(rec.Who()), string(rec.ConnHost()))
|
|
tokenCmd := fmt.Sprintf("echo \"%s\" | tee -a ~/.xs_id", token)
|
|
cmdStatus, runErr := runShellAs(string(rec.Who()), hname, string(rec.TermType()), tokenCmd, false, hc, chaffEnabled)
|
|
// Returned hopefully via an EOF or exit/logout;
|
|
// Clear current op so user can enter next, or EOF
|
|
rec.SetOp([]byte{0})
|
|
if runErr != nil {
|
|
logger.LogErr(fmt.Sprintf("[Error generating autologin token for %s@%s]\n", rec.Who(), hname)) // nolint: gosec,errcheck
|
|
} else {
|
|
log.Printf("[Autologin token generation completed for %s@%s, status %d]\n", rec.Who(), hname, cmdStatus)
|
|
hc.SetStatus(xsnet.CSOType(cmdStatus))
|
|
}
|
|
} else if rec.Op()[0] == 'c' {
|
|
// Non-interactive command
|
|
addr := hc.RemoteAddr()
|
|
hname := goutmp.GetHost(addr.String())
|
|
logger.LogNotice(fmt.Sprintf("[Running command for [%s@%s]]\n", rec.Who(), hname)) // nolint: gosec,errcheck
|
|
cmdStatus, runErr := runShellAs(string(rec.Who()), hname, string(rec.TermType()), string(rec.Cmd()), false, hc, chaffEnabled)
|
|
// Returned hopefully via an EOF or exit/logout;
|
|
// Clear current op so user can enter next, or EOF
|
|
rec.SetOp([]byte{0})
|
|
if runErr != nil {
|
|
logger.LogErr(fmt.Sprintf("[Error spawning cmd for %s@%s]\n", rec.Who(), hname)) // nolint: gosec,errcheck
|
|
} else {
|
|
logger.LogNotice(fmt.Sprintf("[Command completed for %s@%s, status %d]\n", rec.Who(), hname, cmdStatus)) // nolint: gosec,errcheck
|
|
hc.SetStatus(xsnet.CSOType(cmdStatus))
|
|
}
|
|
} else if rec.Op()[0] == 's' {
|
|
// Interactive session
|
|
addr := hc.RemoteAddr()
|
|
hname := goutmp.GetHost(addr.String())
|
|
logger.LogNotice(fmt.Sprintf("[Running shell for [%s@%s]]\n", rec.Who(), hname)) // nolint: gosec,errcheck
|
|
|
|
cmdStatus, runErr := runShellAs(string(rec.Who()), hname, string(rec.TermType()), string(rec.Cmd()), true, hc, chaffEnabled)
|
|
// Returned hopefully via an EOF or exit/logout;
|
|
// Clear current op so user can enter next, or EOF
|
|
rec.SetOp([]byte{0})
|
|
if runErr != nil {
|
|
Log.Err(fmt.Sprintf("[Error spawning shell for %s@%s]\n", rec.Who(), hname)) // nolint: gosec,errcheck
|
|
} else {
|
|
logger.LogNotice(fmt.Sprintf("[Shell completed for %s@%s, status %d]\n", rec.Who(), hname, cmdStatus)) // nolint: gosec,errcheck
|
|
hc.SetStatus(xsnet.CSOType(cmdStatus))
|
|
}
|
|
} else if rec.Op()[0] == 'D' {
|
|
// File copy (destination) operation - client copy to server
|
|
log.Printf("[Client->Server copy]\n")
|
|
addr := hc.RemoteAddr()
|
|
hname := goutmp.GetHost(addr.String())
|
|
logger.LogNotice(fmt.Sprintf("[Running copy for [%s@%s]]\n", rec.Who(), hname)) // nolint: gosec,errcheck
|
|
cmdStatus, runErr := runClientToServerCopyAs(string(rec.Who()), string(rec.TermType()), hc, string(rec.Cmd()), chaffEnabled)
|
|
// Returned hopefully via an EOF or exit/logout;
|
|
// Clear current op so user can enter next, or EOF
|
|
rec.SetOp([]byte{0})
|
|
if runErr != nil {
|
|
logger.LogErr(fmt.Sprintf("[Error running cp for %s@%s]\n", rec.Who(), hname)) // nolint: gosec,errcheck
|
|
} else {
|
|
logger.LogNotice(fmt.Sprintf("[Command completed for %s@%s, status %d]\n", rec.Who(), hname, cmdStatus)) // nolint: gosec,errcheck
|
|
}
|
|
// TODO: Test this with huge files.. see Bug #22 - do we need to
|
|
// sync w/sender (client) that we've gotten all data?
|
|
hc.SetStatus(xsnet.CSOType(cmdStatus))
|
|
|
|
// Send CSOExitStatus *before* client closes channel
|
|
s := make([]byte, 4)
|
|
binary.BigEndian.PutUint32(s, cmdStatus)
|
|
log.Printf("** cp writing closeStat %d at Close()\n", cmdStatus)
|
|
hc.WritePacket(s, xsnet.CSOExitStatus) // nolint: gosec,errcheck
|
|
} else if rec.Op()[0] == 'S' {
|
|
// File copy (src) operation - server copy to client
|
|
log.Printf("[Server->Client copy]\n")
|
|
addr := hc.RemoteAddr()
|
|
hname := goutmp.GetHost(addr.String())
|
|
logger.LogNotice(fmt.Sprintf("[Running copy for [%s@%s]]\n", rec.Who(), hname)) // nolint: gosec,errcheck
|
|
cmdStatus, runErr := runServerToClientCopyAs(string(rec.Who()), string(rec.TermType()), hc, string(rec.Cmd()), chaffEnabled)
|
|
if runErr != nil {
|
|
logger.LogErr(fmt.Sprintf("[Error spawning cp for %s@%s]\n", rec.Who(), hname)) // nolint: gosec,errcheck
|
|
} else {
|
|
// Returned hopefully via an EOF or exit/logout;
|
|
logger.LogNotice(fmt.Sprintf("[Command completed for %s@%s, status %d]\n", rec.Who(), hname, cmdStatus)) // nolint: gosec,errcheck
|
|
}
|
|
// HACK: Bug #22: (xc) Need to wait for rcvr to get final data
|
|
// TODO: Await specific msg from client to inform they have gotten all data from the tarpipe
|
|
time.Sleep(time.Duration(900 * time.Millisecond)) // Let rcvr set this on setup?
|
|
|
|
// Clear current op so user can enter next, or EOF
|
|
rec.SetOp([]byte{0})
|
|
hc.SetStatus(xsnet.CSOType(cmdStatus))
|
|
//fmt.Println("Waiting for EOF from other end.")
|
|
//_, _ = hc.Read(nil /*ackByte*/)
|
|
//fmt.Println("Got remote end ack.")
|
|
} else {
|
|
logger.LogErr(fmt.Sprintln("[Bad xs.Session]")) // nolint: gosec,errcheck
|
|
}
|
|
return
|
|
}(&conn) // nolint: errcheck
|
|
} // Accept() success
|
|
} //endfor
|
|
//logger.LogNotice(fmt.Sprintln("[Exiting]")) // nolint: gosec,errcheck
|
|
}
|