{"record":{"id":"a6b950d092a61638","repo":"JuliusBrussee/caveman","slug":"native-session-key-chmod-dir-w","errorCode":null,"errorMessage":"native session key chmod dir: %w","messagePattern":"native session key chmod dir: %w","errorType":"console","errorClass":null,"httpStatus":null,"severity":"error","filePath":"proxy/internal/nativeruntime/marker.go","lineNumber":29,"sourceCode":"\t\"fmt\"\n\t\"os\"\n\t\"path/filepath\"\n\t\"regexp\"\n)\n\nconst sessionKeyBytes = 32\n\nvar markerPattern = regexp.MustCompile(`\\[\\[caveman-session-v1 sid=\"([A-Za-z0-9_-]{1,384})\" sig=\"([0-9a-f]{64})\"\\]\\]`)\n\n// LoadOrCreateSessionKey returns one user-only HMAC key shared by CLI adapters\n// and local proxy. O_EXCL makes concurrent first startup converge on one key.\nfunc LoadOrCreateSessionKey(home string) ([]byte, error) {\n\tdir := filepath.Join(home, \"runtime\")\n\tif err := os.MkdirAll(dir, 0o700); err != nil {\n\t\treturn nil, fmt.Errorf(\"native session key mkdir: %w\", err)\n\t}\n\tif err := os.Chmod(dir, 0o700); err != nil {\n\t\treturn nil, fmt.Errorf(\"native session key chmod dir: %w\", err)\n\t}\n\tpath := filepath.Join(dir, \"session.key\")\n\tkey := make([]byte, sessionKeyBytes)\n\tif _, err := rand.Read(key); err != nil {\n\t\treturn nil, fmt.Errorf(\"native session key random: %w\", err)\n\t}\n\tfile, err := os.OpenFile(path, os.O_WRONLY|os.O_CREATE|os.O_EXCL, 0o600)\n\tif err == nil {\n\t\tif _, writeErr := file.Write(key); writeErr != nil {\n\t\t\t_ = file.Close()\n\t\t\t_ = os.Remove(path)\n\t\t\treturn nil, fmt.Errorf(\"native session key write: %w\", writeErr)\n\t\t}\n\t\tif syncErr := file.Sync(); syncErr != nil {\n\t\t\t_ = file.Close()\n\t\t\t_ = os.Remove(path)\n\t\t\treturn nil, fmt.Errorf(\"native session key sync: %w\", syncErr)\n\t\t}","sourceCodeStart":11,"sourceCodeEnd":47,"githubUrl":"https://github.com/JuliusBrussee/caveman/blob/27d5a3981a347890211bb1bf2439e5c821a63bc9/proxy/internal/nativeruntime/marker.go#L11-L47","documentation":"After MkdirAll succeeds, LoadOrCreateSessionKey explicitly Chmods the runtime directory to 0700 so the session key directory is user-only even if it pre-existed with looser modes. Failure means chmod(2) returned an error — most commonly the process no longer owns the directory (running under a different user than the one that created it) or the filesystem does not support permission changes.","triggerScenarios":"Directory created by root during install, then proxy run as normal user; FAT/NTFS or some network filesystems where chmod is unsupported; directory on NFS with root-squash mapping.","commonSituations":"Mixed-user setups (installed with sudo, run as user, or vice versa); container volumes mounted from Windows hosts.","solutions":["Make ownership consistent: sudo chown -R $(whoami) <home>/runtime","Run the proxy under the same user that owns the home directory","Move the runtime dir off filesystems that ignore chmod, or accept the failure is environmental and remove the pre-existing dir so it is recreated by the running user"],"exampleFix":"# before\nruntime dir owned by root, proxy runs as 'beagle' -> Error[1067]\n\n# after\nsudo chown -R beagle:beagle ~/.caveman/runtime && chmod 700 ~/.caveman/runtime","handlingStrategy":"validation","validationCode":"func runtimeDirOwned(home string) bool {\n    fi, err := os.Stat(filepath.Join(home, \"runtime\"))\n    return err == nil && fi.IsDir() && fi.Mode().Perm() == 0o700 &&\n        os.Geteuid() == /* owner uid of fi */ int(fi.Sys().(*syscall.Stat_t).Uid)\n}","typeGuard":null,"tryCatchPattern":null,"preventionTips":["Keep install-time and run-time users identical","Avoid chmod-ignoring filesystems (FAT/CIFS) for the home directory","Repair ownership during upgrades: chown -R before restart"],"tags":["filesystem","permissions","nativeruntime","session-key"],"backgroundTag":null,"analyzedSha":"27d5a3981a347890211bb1bf2439e5c821a63bc9","analyzedAt":"2026-08-15T09:26:11.751Z","schemaVersion":2},"datasetVersion":"2026-08-15T17:31:12.345Z"}