Expose proxy host to permissions system

.goreleaser.yaml

@@ -0,0 +1,70 @@
+before:
+  hooks:
+    - go mod tidy
+builds:
+  - id: seashell
+    env:
+      - CGO_ENABLED=0
+    binary: seashell
+    goos:
+      - linux
+    goarch:
+      - amd64
+      - "386"
+      - arm64
+      - arm
+      - riscv64
+archives:
+  - files:
+      - seashell.service
+nfpms:
+  - id: seashell
+    description: "SSH server with virtual hosts and username-based routing"
+    homepage: 'https://gitea.elara.ws/Elara6331/seashell'
+    maintainer: 'Elara Ivy <elara@elara.ws>'
+    license: AGPLv3
+    formats:
+      - deb
+      - rpm
+      - apk
+      - archlinux
+    provides:
+      - seashell
+    conflicts:
+      - seashell
+    contents:
+      - src: seashell.service
+        dst: /etc/systemd/system/seashell.service
+aurs:
+  - name: seashell-bin
+    description: "SSH server with virtual hosts and username-based routing"
+    homepage: 'https://gitea.elara.ws/Elara6331/seashell'
+    maintainers:
+      - 'Elara Ivy <elara@elara.ws>'
+    license: AGPLv3
+    private_key: '{{ .Env.AUR_KEY }}'
+    git_url: 'ssh://aur@aur.archlinux.org/seashell-bin.git'
+    provides:
+      - seashell
+    conflicts:
+      - seashell
+    package: |-
+      # binaries
+      install -Dm755 ./seashell "${pkgdir}/usr/bin/seashell"
+      
+      # services
+      install -Dm644 ./seashell.service "${pkgdir}/etc/systemd/system/seashell.service"      
+release:
+  gitea:
+    owner: Elara6331
+    name: seashell
+gitea_urls:
+  api: 'https://gitea.elara.ws/api/v1/'
+  download: 'https://gitea.elara.ws'
+  skip_tls_verify: false
+checksum:
+  name_template: 'checksums.txt'
+snapshot:
+  name_template: "{{ incpatch .Version }}-next"
+changelog:
+  sort: asc

.woodpecker.yml

@@ -0,0 +1,25 @@
+labels:
+  platform: linux/amd64
+
+steps:
+  docker:
+    image: gitea.elara.ws/elara6331/builder
+    environment:
+      - REGISTRY=gitea.elara.ws
+      - REGISTRY_USERNAME=Elara6331
+      - KO_DOCKER_REPO=gitea.elara.ws/elara6331
+      - KO_DEFAULTBASEIMAGE=gitea.elara.ws/elara6331/static
+    secrets: [ registry_password ]
+    commands:
+      - registry-login
+      - ko build -B --platform=linux/amd64,linux/arm64,linux/riscv64 -t latest,${CI_COMMIT_TAG} --sbom=none
+    when:
+      event: tag
+  
+  release:
+    image: goreleaser/goreleaser
+    commands:
+      - goreleaser release
+    secrets: [ gitea_token, aur_key ]
+    when:
+      event: tag

README.md

@@ -1,5 +1,7 @@
 <p align="center">
-<img src="assets/seashell-text.svg" width="250">
+<img src="assets/seashell-text.svg" width="250" alt="Seashell logo"><br><br>
+<a href="https://goreportcard.com/report/go.elara.ws/seashell"><img src="https://goreportcard.com/badge/go.elara.ws/seashell?style=for-the-badge" alt="Go Report Card"></a>&nbsp;
+<a href="https://gitea.elara.ws/Elara6331/seashell/wiki/Home"><img src="https://img.shields.io/badge/read%20the-docs-purple?style=for-the-badge" alt="Read the Docs"></a>
 </p>
 
 ---
@@ -64,7 +66,7 @@ See the [serial](https://gitea.elara.ws/Elara6331/seashell/wiki/Backends#serial)
 
 Seashell can proxy another SSH server. In this case, your client will authenticate to seashell and then seashell will authenticate to the target server, so you should provide seashell with a private key to use for authentication and encryption. If you don't provide this, seashell will ask the authenticating user for the target server's password.
 
-The proxy backend takes no extra arguments, so the `ssh` command only requires your username and the routing path:
+Here's an example command:
 
 ```bash
 ssh user:myproxy@ssh.example.com

auth.go

@@ -1,3 +1,24 @@
+/*
+ * Seashell - SSH server with virtual hosts and username-based routing
+ *
+ * Copyright (C) 2024 Elara6331 <elara@elara.ws>
+ *
+ * This file is part of Seashell.
+ *
+ * Seashell is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * Seashell 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with Seashell.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
 package main
 
 import (

internal/backends/backends.go

@@ -22,8 +22,6 @@
 package backends
 
 import (
-	"strings"
-
 	"github.com/zclconf/go-cty/cty"
 	"go.elara.ws/seashell/internal/config"
 	"go.elara.ws/seashell/internal/router"
@@ -84,17 +82,6 @@ func ctyObjToStringMap(o *cty.Value) map[string]string {
 	return out
 }
 
-// sshGetenv gets an environment variable from the SSH session
-func sshGetenv(env []string, key string) string {
-	for _, kv := range env {
-		before, after, ok := strings.Cut(kv, "=")
-		if ok && before == key {
-			return after
-		}
-	}
-	return ""
-}
-
 // valueOr returns the value that v points to
 // or a default value if v is nil.
 func valueOr[T any](v *T, or T) T {

internal/backends/docker.go

@@ -41,6 +41,7 @@ type dockerSettings struct {
 	Command    *cty.Value `cty:"command"`
 	Privileged *bool      `cty:"privileged"`
 	User       *string    `cty:"user"`
+	UserMap    *cty.Value `cty:"user_map"`
 }
 
 // Docker is the docker backend. It returns a handler that connects
@@ -62,6 +63,17 @@ func Docker(route config.Route) router.Handler {
 		if !ok {
 			return errors.New("this route only accepts pty sessions (try adding the -t flag)")
 		}
+		
+		if opts.User == nil {
+			userMap := ctyObjToStringMap(opts.UserMap)
+			user, _ := sshctx.GetUser(sess.Context())
+
+			if muser, ok := userMap[user.Name]; ok {
+				opts.User = &muser
+			} else {
+				opts.User = &user.Name
+			}
+		}
 
 		c, err := client.NewClientWithOpts(
 			client.WithHostFromEnv(),
@@ -72,11 +84,6 @@ func Docker(route config.Route) router.Handler {
 			return err
 		}
 
-		if opts.User == nil {
-			envUser := sshGetenv(sess.Environ(), "DOCKER_USER")
-			opts.User = &envUser
-		}
-
 		cmd := sess.Command()
 		if len(cmd) == 0 {
 			cmd = ctyTupleToStrings(opts.Command)

internal/backends/nomad.go

@@ -150,7 +150,7 @@ func Nomad(route config.Route) router.Handler {
 				return errors.New("task group not found")
 			}
 
-			var taskName = args[2]
+			taskName := args[2]
 			if taskName == "" {
 				taskName = group.Tasks[0].Name
 			}
@@ -189,7 +189,7 @@ func Nomad(route config.Route) router.Handler {
 				}
 			}
 
-			var taskName = args[3]
+			taskName := args[3]
 			if taskName == "" {
 				taskName = group.Tasks[0].Name
 			}

internal/backends/proxy.go

@@ -27,6 +27,8 @@ import (
 	"io"
 	"net"
 	"os"
+	"path"
+	"strconv"
 	"strings"
 
 	"github.com/gliderlabs/ssh"
@@ -41,20 +43,18 @@ import (
 
 // proxySettings represents settings for the proxy backend.
 type proxySettings struct {
-	Server      string     `cty:"server"`
+	Host        *string    `cty:"host"`
+	Hosts       *cty.Value `cty:"hosts"`
 	User        *string    `cty:"user"`
 	PrivkeyPath *string    `cty:"privkey"`
-	UserMap     *cty.Value `cty:"userMap"`
+	UserMap     *cty.Value `cty:"user_map"`
 }
 
-// Proxy is the proxy backend. It returns a handler that establishes a proxy 
+// Proxy is the proxy backend. It returns a handler that establishes a proxy
 // session to a remote server based on the provided configuration.
 func Proxy(route config.Route) router.Handler {
 	return func(sess ssh.Session, arg string) error {
 		user, _ := sshctx.GetUser(sess.Context())
-		if !route.Permissions.IsAllowed(user, "*") {
-			return router.ErrUnauthorized
-		}
 
 		var opts proxySettings
 		err := gocty.FromCtyValue(route.Settings, &opts)
@@ -70,7 +70,7 @@ func Proxy(route config.Route) router.Handler {
 		if opts.User == nil {
 			userMap := ctyObjToStringMap(opts.UserMap)
 			user, _ := sshctx.GetUser(sess.Context())
-			
+
 			if muser, ok := userMap[user.Name]; ok {
 				opts.User = &muser
 			} else {
@@ -78,8 +78,55 @@ func Proxy(route config.Route) router.Handler {
 			}
 		}
 
+		matched := false
+		addr := arg
+		var portstr, pattern string
+		if opts.Host == nil {
+			hosts := ctyTupleToStrings(opts.Hosts)
+			if len(hosts) == 0 {
+				return errors.New("no host configuration provided")
+			}
+
+			for _, hostPattern := range hosts {
+				pattern, portstr, ok = strings.Cut(hostPattern, ":")
+				if !ok {
+					// addr is already set by the above statement, so just set the default port
+					portstr = "22"
+				}
+
+				matched, err = path.Match(pattern, arg)
+				if err != nil {
+					return err
+				}
+
+				if matched {
+					addr = arg
+					break
+				}
+			}
+		} else {
+			addr, portstr, ok = strings.Cut(*opts.Host, ":")
+			if !ok {
+				// addr is already set by the above statement, so just set the default port
+				portstr = "22"
+			}
+		}
+
+		if !route.Permissions.IsAllowed(user, addr) {
+			return router.ErrUnauthorized
+		}
+
+		if !matched {
+			return errors.New("provided argument doesn't match any host patterns in configuration")
+		}
+
+		port, err := strconv.ParseUint(portstr, 10, 16)
+		if err != nil {
+			return err
+		}
+
 		auth := goph.Auth{
-			gossh.PasswordCallback(requestPassword(opts, sess)),
+			gossh.PasswordCallback(requestPassword(opts, sess, addr)),
 		}
 
 		if opts.PrivkeyPath != nil {
@@ -96,24 +143,26 @@ func Proxy(route config.Route) router.Handler {
 			auth = append(goph.Auth{gossh.PublicKeys(pk)}, auth...)
 		}
 
-		c, err := goph.New(*opts.User, opts.Server, auth)
+		c, err := goph.NewConn(&goph.Config{
+			Auth: auth,
+			User: *opts.User,
+			Addr: addr,
+			Port: uint(port),
+			Callback: func(host string, remote net.Addr, key gossh.PublicKey) error {
+				found, err := goph.CheckKnownHost(host, remote, key, "")
+				if !found {
+					if err = goph.AddKnownHost(host, remote, key, ""); err != nil {
+						return err
+					}
+				} else if err != nil {
+					return err
+				}
+				return nil
+			},
+		})
 		if err != nil {
 			return err
 		}
-		
-		knownHostHandler, err := goph.DefaultKnownHosts()
-		if err != nil {
-			return err
-		}
-		
-		c.Config.Callback = func(host string, remote net.Addr, key gossh.PublicKey) error {
-			println("hi")
-			err = goph.AddKnownHost(host, remote, key, "")
-			if err != nil {
-				return err
-			}
-			return knownHostHandler(host, remote, key) 
-		}
 
 		baseCmd := sess.Command()
 
@@ -165,9 +214,9 @@ func Proxy(route config.Route) router.Handler {
 }
 
 // requestPassword asks the client for the remote server's password
-func requestPassword(opts proxySettings, sess ssh.Session) func() (secret string, err error) {
+func requestPassword(opts proxySettings, sess ssh.Session, addr string) func() (secret string, err error) {
 	return func() (secret string, err error) {
-		_, err = fmt.Fprintf(sess.Stderr(), "Password for %s@%s: ", *opts.User, opts.Server)
+		_, err = fmt.Fprintf(sess.Stderr(), "Password for %s@%s: ", *opts.User, addr)
 		if err != nil {
 			return "", err
 		}
@@ -187,7 +236,7 @@ func sshHandleResize(resizeCh <-chan ssh.Window, cmd *goph.Cmd) {
 
 // readPassword reads a password from the SSH session, sending an asterisk
 // for each character typed.
-// 
+//
 // It handles interrupts (Ctrl+C), EOF (Ctrl+D), and backspace.
 // It returns what it read once it receives a carriage return or a newline.
 func readPassword(sess ssh.Session) (string, error) {

internal/backends/serial.go

@@ -95,7 +95,7 @@ func Serial(route config.Route) router.Handler {
 				file, baudRate, config = filepath.Join(*opts.Directory, args[0]), args[1], args[2]
 			}
 		}
-		
+
 		if !route.Permissions.IsAllowed(user, filepath.Base(file)) {
 			return router.ErrUnauthorized
 		}

internal/config/permissions.go

@@ -29,7 +29,7 @@ import (
 type PermissionsMap map[string]map[string][]string
 
 // IsAllowed checks if the user has permissions for all the specified items.
-// 
+//
 // The default policy is deny, and denials take priority, so if one item
 // in items is set to deny, IsAllowed will always return false, even if
 // other items are explicitly allowed.

keys.go

@@ -1,3 +1,24 @@
+/*
+ * Seashell - SSH server with virtual hosts and username-based routing
+ *
+ * Copyright (C) 2024 Elara6331 <elara@elara.ws>
+ *
+ * This file is part of Seashell.
+ *
+ * Seashell is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * Seashell 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with Seashell.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
 package main
 
 import (

seashell.ex.hcl

@@ -20,7 +20,16 @@ route "srv" {
     backend = "proxy"
     match = "srv"
     settings = {
-        server = "1.2.3.4"
+        host = "1.2.3.4"
+        privkey = "/home/elara/.ssh/id_ed25519"
+    }
+}
+
+route "cluster" {
+    backend = "proxy"
+    match = "cluster\\.(.+)"
+    settings = {
+        hosts = ["node*", "nas", "192.168.1.*"]
         privkey = "/home/elara/.ssh/id_ed25519"
     }
 }

seashell.service

@@ -0,0 +1,11 @@
+[Unit]
+Description=Seashell SSH Server
+After=network.target
+
+[Service]
+ExecStart=seashell
+Restart=always
+StandardOutput=journal
+
+[Install]
+WantedBy=default.target