| 1 | //go:build linux |
| 2 | |
| 3 | package host |
| 4 | |
| 5 | import ( |
| 6 | "bufio" |
| 7 | "bytes" |
| 8 | "context" |
| 9 | "encoding/json" |
| 10 | "errors" |
| 11 | "io" |
| 12 | "net" |
| 13 | "os" |
| 14 | "path/filepath" |
| 15 | "sync" |
| 16 | "time" |
| 17 | |
| 18 | "github.com/carlosframework/platform/internal/activator" |
| 19 | "github.com/carlosframework/platform/internal/controlsock" |
| 20 | "github.com/carlosframework/platform/internal/hostbox" |
| 21 | "github.com/carlosframework/platform/internal/hostclaim" |
| 22 | "golang.org/x/sys/unix" |
| 23 | ) |
| 24 | |
| 25 | const filesSeedSocket = "/run/carlos/files-seed.sock" |
| 26 | |
| 27 | type filesSeedRequest struct { |
| 28 | Verb string `json:"verb"` |
| 29 | Host string `json:"host,omitempty"` |
| 30 | } |
| 31 | type filesSeedReply struct { |
| 32 | Text string `json:"text,omitempty"` |
| 33 | Code *int `json:"code,omitempty"` |
| 34 | } |
| 35 | type filesSeedServer struct { |
| 36 | listener *net.UnixListener |
| 37 | cancel context.CancelFunc |
| 38 | done chan struct{} |
| 39 | handlers sync.WaitGroup |
| 40 | finalize func(context.Context) error |
| 41 | } |
| 42 | type filesSeedStream struct { |
| 43 | conn net.Conn |
| 44 | encoder *json.Encoder |
| 45 | } |
| 46 | |
| 47 | func (s filesSeedStream) Write(p []byte) (int, error) { |
| 48 | s.conn.SetWriteDeadline(time.Now().Add(5 * time.Second)) |
| 49 | if err := s.encoder.Encode(filesSeedReply{Text: string(p)}); err != nil { |
| 50 | return 0, err |
| 51 | } |
| 52 | return len(p), nil |
| 53 | } |
| 54 | |
| 55 | func startFilesSeedSocket(ctx context.Context, ready <-chan struct{}, path string, auth func(context.Context, *net.UnixConn) error, run func(context.Context, string, io.Writer) error) (*filesSeedServer, error) { |
| 56 | select { |
| 57 | case <-ctx.Done(): |
| 58 | return nil, ctx.Err() |
| 59 | case <-ready: |
| 60 | } |
| 61 | if err := ctx.Err(); err != nil { |
| 62 | return nil, err |
| 63 | } |
| 64 | if auth == nil || run == nil { |
| 65 | return nil, hostbox.ErrUnsupported |
| 66 | } |
| 67 | parent, err := os.Lstat(filepath.Dir(path)) |
| 68 | if err != nil { |
| 69 | return nil, err |
| 70 | } |
| 71 | var dir unix.Stat_t |
| 72 | if err := unix.Lstat(filepath.Dir(path), &dir); err != nil { |
| 73 | return nil, err |
| 74 | } |
| 75 | if !parent.IsDir() || parent.Mode()&os.ModeSymlink != 0 || parent.Mode().Perm()&0022 != 0 || int(dir.Uid) != os.Geteuid() { |
| 76 | return nil, ErrClaimStopIdentity |
| 77 | } |
| 78 | if err := removeStaleFilesSeedSocket(ctx, path); err != nil { |
| 79 | return nil, err |
| 80 | } |
| 81 | listener, err := net.ListenUnix("unix", &net.UnixAddr{Name: path, Net: "unix"}) |
| 82 | if err != nil { |
| 83 | return nil, err |
| 84 | } |
| 85 | if err := os.Chmod(path, 0600); err != nil { |
| 86 | listener.Close() |
| 87 | return nil, err |
| 88 | } |
| 89 | if err := ctx.Err(); err != nil { |
| 90 | listener.Close() |
| 91 | return nil, err |
| 92 | } |
| 93 | live, cancel := context.WithCancel(ctx) |
| 94 | live, finish := activator.WithCleanupBudget(live, 30*time.Second) |
| 95 | s := &filesSeedServer{listener: listener, cancel: cancel, done: make(chan struct{})} |
| 96 | stop := context.AfterFunc(live, func() { listener.Close() }) |
| 97 | go func() { |
| 98 | defer close(s.done) |
| 99 | defer finish() |
| 100 | defer stop() |
| 101 | defer listener.Close() |
| 102 | busy := make(chan struct{}, 1) |
| 103 | for { |
| 104 | conn, err := listener.AcceptUnix() |
| 105 | if err != nil { |
| 106 | break |
| 107 | } |
| 108 | select { |
| 109 | case busy <- struct{}{}: |
| 110 | default: |
| 111 | conn.Close() |
| 112 | continue |
| 113 | } |
| 114 | s.handlers.Add(1) |
| 115 | go func() { |
| 116 | defer s.handlers.Done() |
| 117 | defer func() { <-busy }() |
| 118 | defer conn.Close() |
| 119 | serveFilesSeed(live, conn, auth, run) |
| 120 | }() |
| 121 | } |
| 122 | s.handlers.Wait() |
| 123 | }() |
| 124 | return s, nil |
| 125 | } |
| 126 | |
| 127 | func (s *filesSeedServer) close(ctx context.Context) error { |
| 128 | if s == nil { |
| 129 | return nil |
| 130 | } |
| 131 | s.cancel() |
| 132 | s.listener.Close() |
| 133 | select { |
| 134 | case <-s.done: |
| 135 | if s.finalize != nil { |
| 136 | return s.finalize(ctx) |
| 137 | } |
| 138 | return nil |
| 139 | case <-ctx.Done(): |
| 140 | return ctx.Err() |
| 141 | } |
| 142 | } |
| 143 | |
| 144 | func serveFilesSeed(parent context.Context, conn *net.UnixConn, auth func(context.Context, *net.UnixConn) error, run func(context.Context, string, io.Writer) error) { |
| 145 | ctx, cancel := context.WithCancel(parent) |
| 146 | defer cancel() |
| 147 | ctx, finish := activator.WithCleanupBudget(ctx, 30*time.Second) |
| 148 | defer finish() |
| 149 | stop := context.AfterFunc(ctx, func() { conn.Close() }) |
| 150 | defer stop() |
| 151 | conn.SetReadDeadline(time.Now().Add(5 * time.Second)) |
| 152 | if err := auth(ctx, conn); err != nil { |
| 153 | return |
| 154 | } |
| 155 | reader := bufio.NewReaderSize(conn, 1024) |
| 156 | line, err := reader.ReadSlice('\n') |
| 157 | if err != nil || len(line) > 1024 { |
| 158 | return |
| 159 | } |
| 160 | var q filesSeedRequest |
| 161 | decoder := json.NewDecoder(bytes.NewReader(line)) |
| 162 | decoder.DisallowUnknownFields() |
| 163 | if err := decoder.Decode(&q); err != nil { |
| 164 | return |
| 165 | } |
| 166 | // Canonical encoding also rejects duplicate fields and trailing JSON. |
| 167 | canonical, _ := json.Marshal(q) |
| 168 | var compact bytes.Buffer |
| 169 | if json.Compact(&compact, line) != nil || !bytes.Equal(compact.Bytes(), canonical) { |
| 170 | return |
| 171 | } |
| 172 | if q.Verb != "seed" { |
| 173 | return |
| 174 | } |
| 175 | if q.Host != "" { |
| 176 | if _, err := hostclaim.Key(q.Host); err != nil { |
| 177 | return |
| 178 | } |
| 179 | } |
| 180 | if err := auth(ctx, conn); err != nil { |
| 181 | return |
| 182 | } |
| 183 | conn.SetReadDeadline(time.Time{}) |
| 184 | monitor := make(chan struct{}) |
| 185 | go func() { defer close(monitor); _, _ = reader.ReadByte(); cancel() }() |
| 186 | stream := filesSeedStream{conn: conn, encoder: json.NewEncoder(conn)} |
| 187 | result := run(ctx, q.Host, stream) |
| 188 | code := filesSeedExitCode(result) |
| 189 | if result != nil { |
| 190 | _, _ = stream.Write([]byte(result.Error() + "\n")) |
| 191 | } |
| 192 | conn.SetWriteDeadline(time.Now().Add(time.Second)) |
| 193 | _ = stream.encoder.Encode(filesSeedReply{Code: &code}) |
| 194 | conn.Close() |
| 195 | <-monitor |
| 196 | } |
| 197 | |
| 198 | func filesSeedClient(ctx context.Context, host string, out io.Writer, uid int) error { |
| 199 | var st unix.Stat_t |
| 200 | if err := unix.Lstat(filesSeedSocket, &st); err != nil { |
| 201 | return errors.Join(errFilesSeedDelegation, err) |
| 202 | } |
| 203 | if st.Mode&unix.S_IFMT != unix.S_IFSOCK || st.Mode&0777 != 0600 || st.Uid != uint32(uid) { |
| 204 | return ErrClaimStopIdentity |
| 205 | } |
| 206 | conn, err := (&net.Dialer{}).DialContext(ctx, "unix", filesSeedSocket) |
| 207 | if err != nil { |
| 208 | return errors.Join(errFilesSeedDelegation, err) |
| 209 | } |
| 210 | defer conn.Close() |
| 211 | stop := context.AfterFunc(ctx, func() { conn.Close() }) |
| 212 | defer stop() |
| 213 | if err := authenticateFilesSeedPeer(ctx, conn.(*net.UnixConn), uid, true); err != nil { |
| 214 | return err |
| 215 | } |
| 216 | var after unix.Stat_t |
| 217 | if err := unix.Lstat(filesSeedSocket, &after); err != nil || st.Dev != after.Dev || st.Ino != after.Ino { |
| 218 | return ErrClaimStopIdentity |
| 219 | } |
| 220 | if err := json.NewEncoder(conn).Encode(filesSeedRequest{Verb: "seed", Host: host}); err != nil { |
| 221 | return err |
| 222 | } |
| 223 | reader := bufio.NewReaderSize(conn, 64*1024) |
| 224 | for { |
| 225 | line, err := reader.ReadSlice('\n') |
| 226 | if err != nil { |
| 227 | return err |
| 228 | } |
| 229 | var reply filesSeedReply |
| 230 | if err := json.Unmarshal(line, &reply); err != nil { |
| 231 | return err |
| 232 | } |
| 233 | if reply.Text != "" { |
| 234 | if _, err := io.WriteString(out, reply.Text); err != nil { |
| 235 | return err |
| 236 | } |
| 237 | } |
| 238 | if reply.Code != nil { |
| 239 | switch *reply.Code { |
| 240 | case 0: |
| 241 | return nil |
| 242 | case 2: |
| 243 | return filesSeedIncompleteError{hostbox.ErrChanged} |
| 244 | default: |
| 245 | return hostbox.ErrChanged |
| 246 | } |
| 247 | } |
| 248 | } |
| 249 | } |
| 250 | |
| 251 | func startAgentFilesSeed(ctx context.Context, ready <-chan struct{}, svc *activator.Service) (*filesSeedServer, error) { |
| 252 | entry, _ := ctx.Value(claimEntryKey{}).(claimEntry) |
| 253 | resources := entry.Resources |
| 254 | source, ok := productionClaimFilesSource().(*movesFilesSource) |
| 255 | if !ok || entry.Assembly == nil || svc == nil || resources.Manager == nil { |
| 256 | return nil, hostbox.ErrUnsupported |
| 257 | } |
| 258 | if err := NewClaimRoleRootClient(controlsock.Path).KindCapability(ctx, "files-seed"); err != nil { |
| 259 | return nil, err |
| 260 | } |
| 261 | executor := &filesSeedExecutor{assembly: entry.Assembly, service: svc, registry: resources.Registry, source: source} |
| 262 | server, err := startFilesSeedSocket(ctx, ready, filesSeedSocket, func(ctx context.Context, c *net.UnixConn) error { |
| 263 | return authenticateFilesSeedPeer(ctx, c, os.Geteuid(), false) |
| 264 | }, executor.run) |
| 265 | if server != nil { |
| 266 | server.finalize = executor.close |
| 267 | } |
| 268 | return server, err |
| 269 | } |
| 270 | |
| 271 | // Recovery removes only an unchanged, service-owned socket which the kernel |
| 272 | // refused to connect to. A live or uncertain listener always wins. |
| 273 | func removeStaleFilesSeedSocket(ctx context.Context, path string) error { |
| 274 | var before unix.Stat_t |
| 275 | err := unix.Lstat(path, &before) |
| 276 | if errors.Is(err, unix.ENOENT) { |
| 277 | return nil |
| 278 | } |
| 279 | if err != nil { |
| 280 | return err |
| 281 | } |
| 282 | if before.Mode&unix.S_IFMT != unix.S_IFSOCK || before.Mode&0777 != 0600 || int(before.Uid) != os.Geteuid() { |
| 283 | return ErrClaimStopIdentity |
| 284 | } |
| 285 | conn, err := (&net.Dialer{Timeout: time.Second}).DialContext(ctx, "unix", path) |
| 286 | if err == nil { |
| 287 | conn.Close() |
| 288 | return hostbox.ErrChanged |
| 289 | } |
| 290 | if !errors.Is(err, unix.ECONNREFUSED) { |
| 291 | return err |
| 292 | } |
| 293 | var after unix.Stat_t |
| 294 | if err := unix.Lstat(path, &after); err != nil { |
| 295 | return err |
| 296 | } |
| 297 | if before.Dev != after.Dev || before.Ino != after.Ino || before.Ctim != after.Ctim { |
| 298 | return ErrClaimStopIdentity |
| 299 | } |
| 300 | return os.Remove(path) |
| 301 | } |
| 302 | |
amadan