X-Git-Url: https://ruderich.org/simon/gitweb/?a=blobdiff_plain;f=rpc%2Fdial.go;h=c098714cc0759388dd32e0d723819c4b4c598665;hb=HEAD;hp=36092793e005e06991a64fe440b97ca74fac6a88;hpb=f2f2bc47e8729548f3c10117f7f008b547c4afc5;p=safcm%2Fsafcm.git

diff --git a/rpc/dial.go b/rpc/dial.go
index 3609279..fa1efcd 100644
--- a/rpc/dial.go
+++ b/rpc/dial.go
@@ -1,19 +1,7 @@
 // Simple RPC-like protocol: establish new connection and upload helper
 
-// Copyright (C) 2021  Simon Ruderich
-//
-// This program is free software: you can redistribute it and/or modify
-// it under the terms of the GNU General Public License as published by
-// the Free Software Foundation, either version 3 of the License, or
-// (at your option) any later version.
-//
-// This program is distributed in the hope that it will be useful,
-// but WITHOUT ANY WARRANTY; without even the implied warranty of
-// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-// GNU General Public License for more details.
-//
-// You should have received a copy of the GNU General Public License
-// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+// SPDX-License-Identifier: GPL-3.0-or-later
+// Copyright (C) 2021-2024  Simon Ruderich
 
 package rpc
 
@@ -24,19 +12,36 @@ import (
 	"encoding/hex"
 	"fmt"
 	"io"
+	"io/fs"
 	"os/exec"
 	"strconv"
 	"strings"
 
 	"ruderich.org/simon/safcm"
-	"ruderich.org/simon/safcm/remote"
 )
 
-func (c *Conn) DialSSH(remote string) error {
+type SSHConfig struct {
+	Host      string
+	User      string // optional
+	SshConfig string // optional
+
+	RemoteHelpers fs.FS
+}
+
+func (c *Conn) DialSSH(cfg SSHConfig) error {
 	if c.events == nil {
 		return fmt.Errorf("cannot reuse Conn")
 	}
 
+	if cfg.RemoteHelpers == nil {
+		return fmt.Errorf("SSHConfig.RemoteHelpers not set")
+	}
+	c.remoteHelpers = cfg.RemoteHelpers
+
+	remote := cfg.Host
+	if cfg.User != "" {
+		remote = cfg.User + "@" + cfg.Host
+	}
 	c.debugf("DialSSH: connecting to %q", remote)
 
 	opts := "-eu"
@@ -44,8 +49,14 @@ func (c *Conn) DialSSH(remote string) error {
 		// Help debugging by showing executed shell commands
 		opts += "x"
 	}
-	c.cmd = exec.Command("ssh", remote, "/bin/sh", opts)
-	c.remote = remote
+
+	c.sshRemote = remote
+	if cfg.SshConfig != "" {
+		c.sshOpts = []string{"-F", cfg.SshConfig}
+	}
+	c.cmd = exec.Command("ssh",
+		append(append([]string{}, c.sshOpts...),
+			c.sshRemote, "/bin/sh", opts)...)
 
 	stdin, err := c.cmd.StdinPipe()
 	if err != nil {
@@ -67,7 +78,7 @@ func (c *Conn) DialSSH(remote string) error {
 
 	err = c.dialSSH(stdin, stdout)
 	if err != nil {
-		c.Kill()
+		c.Kill() //nolint:errcheck
 		return err
 	}
 	c.conn = safcm.NewGobConn(stdout, stdin)
@@ -94,6 +105,36 @@ func (c *Conn) dialSSH(stdin io.Writer, stdout_ io.Reader) error {
 	path := fmt.Sprintf("/tmp/safcm-remote-%d", uid)
 
 	c.debugf("DialSSH: probing remote at %q", path)
+
+	// Compatibility for different operating systems
+	var compat string
+	switch goos {
+	case "linux":
+		compat = `
+dir_stat='drwxrwxrwt 0 0'
+file_stat="-rwx------ $(id -u) $(id -g)"
+compat_stat() {
+	stat -c '%A %u %g' "$1"
+}
+compat_sha512sum() {
+	sha512sum "$1"
+}
+`
+	case "freebsd", "openbsd":
+		compat = `
+dir_stat='41777 0 0'
+file_stat="100700 $(id -u) $(id -g)"
+compat_stat() {
+	stat -f '%p %u %g' "$1"
+}
+compat_sha512sum() {
+	sha512 -q "$1"
+}
+`
+	default:
+		return fmt.Errorf("internal error: no support for %q", goos)
+	}
+
 	// Use a function so the shell cannot execute the input line-wise.
 	// This is important because we're also using stdin to send data to
 	// the script. If the shell executes the input line-wise then our
@@ -101,29 +142,30 @@ func (c *Conn) dialSSH(stdin io.Writer, stdout_ io.Reader) error {
 	//
 	// The target directory must no permit other users to delete our files
 	// or symlink attacks and arbitrary code execution is possible. For
-	// /tmp this is guaranteed by the sticky bit. Make sure it has the
-	// proper permissions.
+	// /tmp this is guaranteed by the sticky bit. The code verifies the
+	// directory has the proper permissions.
 	//
 	// We cannot use `test -f && test -O` because this is open to TOCTOU
 	// attacks. `stat` gives use the full file state. If the file is owned
-	// by us and not a symlink then it's safe to use (assuming sticky or
-	// directory not writable by others).
+	// by us and not a symlink then it's safe to use (assuming sticky
+	// directory or directory not writable by others).
 	//
 	// `test -e` is only used to prevent error messages if the file
 	// doesn't exist. It does not guard against any races.
 	_, err = fmt.Fprintf(stdin, `
+%s
 f() {
 	x=%q
 
 	dir="$(dirname "$x")"
-	if ! test "$(stat -c '%%A %%u %%g' "$dir")" = 'drwxrwxrwt 0 0'; then
+	if ! test "$(compat_stat "$dir")" = "$dir_stat"; then
 		echo "unsafe permissions on $dir, aborting" >&2
 		exit 1
 	fi
 
-	if test -e "$x" && test "$(stat -c '%%A %%u' "$x")" = "-rwx------ $(id -u)"; then
+	if test -e "$x" && test "$(compat_stat "$x")" = "$file_stat"; then
 		# Report checksum
-		sha512sum "$x"
+		compat_sha512sum "$x"
 	else
 		# Empty checksum to request upload
 		echo
@@ -136,7 +178,6 @@ f() {
 		tmp="$(mktemp "$x.XXXXXX")"
 		# Report filename for upload
 		echo "$tmp"
-
 		# Wait for upload to complete
 		read unused
 
@@ -146,12 +187,14 @@ f() {
 		rm "$tmp"
 		# Make file executable
 		chmod 0700 "$x"
+		# Some BSD create files with group wheel in /tmp
+		chgrp "$(id -g)" "$x"
 	fi
 
-	exec "$x"
+	exec "$x" sync
 }
 f
-`, path)
+`, compat, path)
 	if err != nil {
 		return err
 	}
@@ -160,9 +203,9 @@ f
 		return err
 	}
 
-	// Get embedded helper binary
-	helper, err := remote.Helpers.ReadFile(
-		fmt.Sprintf("helpers/%s-%s", goos, goarch))
+	// Get remote helper binary
+	helper, err := fs.ReadFile(c.remoteHelpers,
+		fmt.Sprintf("%s-%s", goos, goarch))
 	if err != nil {
 		return fmt.Errorf("remote not built for GOOS/GOARCH %s/%s",
 			goos, goarch)
@@ -214,12 +257,14 @@ f
 		path = strings.TrimSuffix(path, "\n")
 
 		c.debugf("DialSSH: uploading new remote to %q at %q",
-			c.remote, path)
+			c.sshRemote, path)
 
-		cmd := exec.Command("ssh", c.remote,
-			fmt.Sprintf("cat > %q", path))
+		cmd := exec.Command("ssh",
+			append(append([]string{}, c.sshOpts...),
+				c.sshRemote,
+				fmt.Sprintf("cat > %q", path))...)
 		cmd.Stdin = bytes.NewReader(helper)
-		err = c.handleStderrAsEvents(cmd)
+		err = c.handleStderrAsEvents(cmd) // cmd.Stderr
 		if err != nil {
 			return err
 		}
@@ -239,7 +284,7 @@ f
 }
 
 func connGetGoos(stdin io.Writer, stdout *bufio.Reader) (string, error) {
-	_, err := fmt.Fprintln(stdin, "uname -o")
+	_, err := fmt.Fprintln(stdin, "uname")
 	if err != nil {
 		return "", err
 	}
@@ -252,10 +297,14 @@ func connGetGoos(stdin io.Writer, stdout *bufio.Reader) (string, error) {
 	// NOTE: Adapt helper uploading in dialSSH() when adding new systems
 	var goos string
 	switch x {
-	case "GNU/Linux":
+	case "Linux":
 		goos = "linux"
+	case "FreeBSD":
+		goos = "freebsd"
+	case "OpenBSD":
+		goos = "openbsd"
 	default:
-		return "", fmt.Errorf("unsupported OS %q (`uname -o`)", x)
+		return "", fmt.Errorf("unsupported OS %q (`uname`)", x)
 	}
 	return goos, nil
 }
@@ -274,8 +323,10 @@ func connGetGoarch(stdin io.Writer, stdout *bufio.Reader) (string, error) {
 	// NOTE: Adapt cmd/safcm-remote/build.sh when adding new architectures
 	var goarch string
 	switch x {
-	case "x86_64":
+	case "x86_64", "amd64":
 		goarch = "amd64"
+	case "armv7l":
+		goarch = "armv7l"
 	default:
 		return "", fmt.Errorf("unsupported arch %q (`uname -m`)", x)
 	}