internal/control/control.go
338 lines · 11295 bytes
1// Package control implements the forge control commands executed over SSH.
2// Every command here is reachable from bare OpenSSH: argv in, JSON or plain
3// text on stdout, diagnostics on stderr, exit code out.
4package control
5
6import (
7 "encoding/json"
8 "errors"
9 "fmt"
10 "io"
11 "reflect"
12 "slices"
13 "strings"
14 "time"
15
16 "gitbay.org/gitbay/internal/config"
17 "gitbay.org/gitbay/internal/protocol"
18 "gitbay.org/gitbay/internal/store"
19)
20
21type Ctx struct {
22 User store.User
23 Scope string // scope of the key that authenticated this session
24 Store *store.Store
25 Cfg config.Config
26 Stdin io.Reader
27 Stdout io.Writer
28 Stderr io.Writer
29 JSON bool
30 // ViaAPI marks requests arriving over HTTP, from the token API or
31 // the web. Every command runs there; nothing is held back for SSH
32 // any more (#234). The flag stays because the rate limiter and the
33 // audit log want to know which door a request came through.
34 ViaAPI bool
35 // ReadOnly is set for read-scoped API tokens.
36 ReadOnly bool
37 // Source identifies the credential behind this session for the audit
38 // log: an SSH key fingerprint, or "api" for token requests.
39 Source string
40 // Cmd is the command being run, set by Dispatch, so a usage error can
41 // print the registered usage rather than a copy of it.
42 Cmd Command
43}
44
45// usage reports a bad invocation with the command's registered usage,
46// the one source of it.
47func (c *Ctx) usage() int {
48 return c.fail(protocol.ExitUsage, "usage: %s", c.Cmd.Usage)
49}
50
51// usageWith reports a specific problem with the arguments, then the
52// registered usage, so a person always sees the shape that was expected.
53func (c *Ctx) usageWith(msg string) int {
54 return c.fail(protocol.ExitUsage, "%s\nusage: %s", msg, c.Cmd.Usage)
55}
56
57type Command struct {
58 Path []string // e.g. ["keys", "add"]
59 // Summary is one line of prose: what the command does, no argument
60 // syntax. Usage is the argument syntax, opening with the command path.
61 // help renders them separately, so neither may carry the other's job.
62 Summary string
63 Usage string
64 ReadsStdin bool
65 ReadOnly bool // safe for read-scoped API tokens
66 Run func(c *Ctx, args []string) int
67}
68
69var registry []Command
70
71func register(cmd Command) { registry = append(registry, cmd) }
72
73// Commands returns the registry, for the bare-ssh reachability test.
74func Commands() []Command { return registry }
75
76// Lookup resolves argv to a command by longest path match, returning the
77// command and the remaining arguments.
78func Lookup(argv []string) (Command, []string, bool) {
79 best := -1
80 var found Command
81 for _, cmd := range registry {
82 if len(cmd.Path) <= len(argv) && slices.Equal(cmd.Path, argv[:len(cmd.Path)]) && len(cmd.Path) > best {
83 best = len(cmd.Path)
84 found = cmd
85 }
86 }
87 if best < 0 {
88 return Command{}, nil, false
89 }
90 return found, argv[best:], true
91}
92
93// Dispatch runs argv for an authenticated session. The dispatcher — not the
94// handlers — enforces key scope: control commands require a full-scope key.
95func Dispatch(c *Ctx, argv []string) int {
96 if len(argv) == 0 {
97 return c.fail(protocol.ExitUsage, "no command given; try: ssh <host> help")
98 }
99 cmd, rest, ok := Lookup(argv)
100 c.Cmd = cmd
101 if !ok {
102 return c.fail(protocol.ExitUsage, "unknown command %q", argv[0])
103 }
104 // Strip the global --json flag wherever it appears, before any
105 // refusal below: a scripted caller needs the envelope most when it is
106 // being told no (#109).
107 args := rest[:0:0]
108 for _, a := range rest {
109 if a == "--json" {
110 c.JSON = true
111 continue
112 }
113 args = append(args, a)
114 }
115 // A runner-scoped key reaches the runner protocol and nothing else, so
116 // the key a CI host holds cannot administer the instance.
117 if c.Scope != "full" && !(c.Scope == "runner" && cmd.Path[0] == "runner") {
118 return c.fail(protocol.ExitDenied, "this key's scope (%s) does not allow control commands; use a key added with --scope full", c.Scope)
119 }
120 if c.ReadOnly && !cmd.ReadOnly {
121 return c.fail(protocol.ExitDenied, "this token is read-only; %s modifies state — mint one with --scope full", joinPath(cmd.Path))
122 }
123 // The SSH listener refuses a disabled account before it gets here; the
124 // API and the web reach Dispatch directly, so the check lives here too.
125 if c.User.Disabled {
126 return c.fail(protocol.ExitDenied, "this account is disabled; ask an instance admin to enable it")
127 }
128 // The admin noun is gated here as well as in each handler, so a new
129 // admin command that forgets requireInstanceAdmin is still refused.
130 if cmd.Path[0] == "admin" && !c.User.IsAdmin {
131 return c.fail(protocol.ExitDenied, "admin commands are for instance admins; ask one")
132 }
133 if c.User.Pending && !pendingAllowed(cmd.Path) {
134 return c.fail(protocol.ExitDenied,
135 "your account is not active yet: verify your email first (email verify <code>, or ask for the mail again with email add)")
136 }
137 if code := limitWrites(c, cmd); code >= 0 {
138 return code
139 }
140 if !cmd.ReadsStdin {
141 c.Stdin = emptyReader{}
142 }
143 code := cmd.Run(c, args)
144 // Every successful mutating command lands in the audit log.
145 if code == protocol.ExitOK && !cmd.ReadOnly {
146 c.Store.Audit(c.User.ID, "cmd "+joinPath(cmd.Path), map[string]any{
147 "argv": auditArgs(args),
148 "source": c.Source,
149 })
150 }
151 return code
152}
153
154// auditArgs is argv with flag values dropped. Secrets never reach argv —
155// they travel on stdin — but prose does: `issue create a/b --title x
156// --body <the whole issue>` used to store the body verbatim, in a table
157// nothing pruned, for a repository that may be private. The identifiers
158// are positional, so keeping those and the flag names says what was done
159// without copying what was written (#122).
160func auditArgs(args []string) []string {
161 out := make([]string, 0, len(args))
162 for i := 0; i < len(args); i++ {
163 a := args[i]
164 if !strings.HasPrefix(a, "--") {
165 out = append(out, a)
166 continue
167 }
168 out = append(out, a)
169 // "--" ends flag parsing; everything after it is positional.
170 if a == "--" {
171 out = append(out, args[i+1:]...)
172 break
173 }
174 // A flag's value is the next argument unless that is itself a
175 // flag, which is how a switch is told from one that takes a value
176 // without consulting the command's spec.
177 if i+1 < len(args) && !strings.HasPrefix(args[i+1], "--") {
178 i++
179 }
180 }
181 return out
182}
183
184// pendingAllowed lists what an unverified self-registered account may do.
185// limitWrites spends one token of the account's write budget, and refuses
186// with the wait when it is empty. Returns -1 when the command may run.
187//
188// Exempt: read-only commands, which cost the instance nothing to serve
189// twice; the runner protocol, which streams a build's log in many small
190// writes and would throttle CI; and the host CLI on the server, which has
191// no account to key on and is already root-equivalent.
192func limitWrites(c *Ctx, cmd Command) int {
193 if cmd.ReadOnly || cmd.Path[0] == "runner" || c.Source == "host" || c.User.ID == 0 {
194 return -1
195 }
196 perMinute := c.Cfg.Limits.WriteRate
197 if perMinute == 0 {
198 perMinute = config.DefaultWriteRate
199 }
200 if perMinute < 0 {
201 return -1
202 }
203 if ok, wait := writes.allow(c.User.ID, perMinute); !ok {
204 return c.fail(protocol.ExitDenied,
205 "too many writes: %d a minute per account; try again in %s",
206 perMinute, wait.Round(time.Second))
207 }
208 return -1
209}
210
211func pendingAllowed(path []string) bool {
212 key := joinPath(path)
213 return key == "email verify" || key == "email add" || key == "whoami" || key == "help"
214}
215
216type emptyReader struct{}
217
218func (emptyReader) Read([]byte) (int, error) { return 0, io.EOF }
219
220// emit writes data as the command result: a JSON envelope under --json,
221// otherwise via the plain formatter.
222func (c *Ctx) emit(data any, plain func(w io.Writer)) int {
223 // A nil slice would serialize as null; consumers should see [].
224 v := reflect.ValueOf(data)
225 if v.Kind() == reflect.Slice && v.IsNil() {
226 data = reflect.MakeSlice(v.Type(), 0, 0).Interface()
227 }
228 // An empty list prints nothing a script would read; the person at
229 // the terminal hears about it on stderr.
230 if !c.JSON && v.Kind() == reflect.Slice && v.Len() == 0 {
231 fmt.Fprintln(c.Stderr, "nothing to list")
232 return protocol.ExitOK
233 }
234 if c.JSON {
235 enc := json.NewEncoder(c.Stdout)
236 enc.SetEscapeHTML(false)
237 if err := enc.Encode(protocol.Envelope{ProtocolVersion: protocol.Version, Data: data}); err != nil {
238 return protocol.ExitFailure
239 }
240 return protocol.ExitOK
241 }
242 plain(c.Stdout)
243 return protocol.ExitOK
244}
245
246// failErr reports an error from a store call: not-found is not-found,
247// and anything else — the database failing, a duplicate, a state that
248// does not allow the change — is a failure. An error about the caller's
249// own arguments goes through failInput instead; this used to default to
250// usage, which turned every refusal into exit 2 (#211).
251func (c *Ctx) failErr(err error) int {
252 if errors.Is(err, store.ErrNotFound) {
253 return c.fail(protocol.ExitNotFound, "%v", err)
254 }
255 return c.fail(protocol.ExitFailure, "%v", err)
256}
257
258// failInput reports an error about the caller's input — a name that does
259// not validate, a flag value out of range, a body that could not be read
260// — as a usage error, unless the database or I/O failed underneath it.
261// A SQLite I/O error used to be a usage error and an HTTP 400 (#107).
262func (c *Ctx) failInput(err error) int {
263 switch {
264 case errors.Is(err, store.ErrNotFound):
265 return c.fail(protocol.ExitNotFound, "%v", err)
266 case store.IsInternal(err):
267 return c.fail(protocol.ExitFailure, "%v", err)
268 }
269 return c.fail(protocol.ExitUsage, "%v", err)
270}
271
272func (c *Ctx) fail(code int, format string, args ...any) int {
273 msg := fmt.Sprintf(format, args...)
274 if c.JSON {
275 enc := json.NewEncoder(c.Stdout)
276 enc.SetEscapeHTML(false)
277 enc.Encode(protocol.Envelope{ProtocolVersion: protocol.Version, Error: msg})
278 } else {
279 fmt.Fprintln(c.Stderr, msg)
280 }
281 return code
282}
283
284func init() {
285 register(Command{
286 Path: []string{"help"},
287 Summary: "list available commands",
288 Usage: "help [<prefix>...]",
289 ReadOnly: true,
290 Run: runHelp,
291 })
292}
293
294// helpEntry is one row of the registry as help reports it.
295type helpEntry struct {
296 Path string `json:"path"`
297 Summary string `json:"summary"`
298 Usage string `json:"usage"`
299}
300
301// runHelp lists the registry, sorted, so a noun's commands sit together.
302// A prefix narrows the listing and adds each command's argument syntax —
303// the only place flags are written down. The unfiltered listing stays one
304// line per command.
305func runHelp(c *Ctx, args []string) int {
306 prefix := joinPath(args)
307 var matched []helpEntry
308 for _, cmd := range registry {
309 p := joinPath(cmd.Path)
310 if prefix != "" && p != prefix && !strings.HasPrefix(p, prefix+" ") {
311 continue
312 }
313 matched = append(matched, helpEntry{Path: p, Summary: cmd.Summary, Usage: cmd.Usage})
314 }
315 if len(matched) == 0 {
316 return c.fail(protocol.ExitNotFound, "no command matches %q; try: help", prefix)
317 }
318 slices.SortFunc(matched, func(a, b helpEntry) int { return strings.Compare(a.Path, b.Path) })
319 return c.emit(matched, func(w io.Writer) {
320 for _, e := range matched {
321 fmt.Fprintf(w, "%-24s %s\n", e.Path, e.Summary)
322 if prefix != "" {
323 fmt.Fprintf(w, " %s\n", e.Usage)
324 }
325 }
326 })
327}
328
329func joinPath(p []string) string {
330 out := ""
331 for i, s := range p {
332 if i > 0 {
333 out += " "
334 }
335 out += s
336 }
337 return out
338}