Add nas.js logic layer (command builders + parsers)

Injection-safe sh -c wrapper (static script + positional args), KWallet password flow into a 0600 cred file for mount, smbclient/-g share parsing, findmnt mounted-state parsing, and the pkexec helper invocations. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
2026-07-15 14:22:03 +02:00
parent a462d8ab4f
commit 43088a2316
1 changed files with 181 additions and 0 deletions
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+/*
+ * nas.js — command builders + output parsers for the Synology NAS plasmoid.
+ *
+ * These functions are pure: they build shell command strings and parse the
+ * text those commands produce. The QML layer owns a Plasma5Support executable
+ * DataSource and actually runs them.
+ *
+ * Security model:
+ *   - The plasma5support "executable" engine does NOT use a shell; it tokenises
+ *     with KShell and runs the program directly. So every command is wrapped as
+ *     `sh -c '<STATIC SCRIPT>' _ <arg1> <arg2> ...`. The script text is constant
+ *     (no interpolation) and all dynamic, possibly-hostile values arrive as
+ *     positional parameters ($1, $2, ...). This makes shell injection via a
+ *     share/host/user name impossible.
+ *   - Passwords live in KWallet. On mount we read the password *inside* the
+ *     shell straight into a 0600 credentials file — it never appears in QML,
+ *     in argv, or in `ps`. (The one exception is the initial save in the config
+ *     page, where the freshly-typed password is handed to kwallet-query.)
+ */
+
+// KWallet folder + wallet used for all stored NAS passwords.
+var WALLET = "kdewallet";
+var WALLET_FOLDER = "Synology NAS";
+var HELPER = "/usr/lib/synology-nas/helper";
+
+// POSIX single-quote escaping: wrap in '...' and replace ' with '\''.
+function sq(s) {
+    return "'" + String(s).replace(/'/g, "'\\''") + "'";
+}
+
+// Build `sh -c '<script>' _ arg1 arg2 ...` with every arg safely quoted.
+// `script` is trusted constant text; `args` are untrusted runtime values.
+function shCmd(script, args) {
+    var out = "sh -c " + sq(script) + " _";
+    for (var i = 0; i < (args ? args.length : 0); ++i) {
+        out += " " + sq(args[i]);
+    }
+    return out;
+}
+
+// KWallet entry key for a host's credentials.
+function walletKey(host) {
+    return host.id + "/" + (host.username || "");
+}
+
+// Turn a label/host into a safe single path component.
+function safeComponent(s) {
+    return String(s).replace(/[^A-Za-z0-9._-]/g, "_").replace(/^\.+/, "_");
+}
+
+// Resolve the effective mount root (config override -> home/NAS).
+function mountRoot(cfg, home, host) {
+    if (host && host.mountRoot && host.mountRoot.length > 0) return host.mountRoot;
+    if (cfg && cfg.length > 0) return cfg;
+    return home + "/NAS";
+}
+
+// Absolute mount point for a given host + share.
+function mountpointFor(cfg, home, host, share) {
+    var root = mountRoot(cfg, home, host);
+    var seg = safeComponent(host.label && host.label.length ? host.label : host.host);
+    return root + "/" + seg + "/" + safeComponent(share);
+}
+
+// //host/share as passed to mount.cifs.
+function unc(host, share) {
+    return "//" + host.host + "/" + share;
+}
+
+/* ---- command builders -------------------------------------------------- */
+
+// Enumerate shares on a host. Password is pulled from KWallet into the PASSWD
+// env var (read by smbclient) so it never reaches argv.
+function enumerateCmd(host) {
+    var script =
+        "export PASSWD=\"$(kwallet-query -f 'Synology NAS' -r \"$1\" " + WALLET + ")\"\n" +
+        "exec smbclient -L \"//$2\" -U \"$3\" -g -N 2>/dev/null";
+    return shCmd(script, [walletKey(host), host.host, host.username || ""]);
+}
+
+// List currently mounted cifs filesystems (no privilege needed).
+function listMountedCmd() {
+    return shCmd("exec findmnt -rnt cifs -o TARGET,SOURCE", []);
+}
+
+// Mount a share. Reads the password from KWallet into a 0600 cred file, then
+// invokes the privileged helper via pkexec. The cred file is always removed.
+//
+// `settings` = { defaultMountRoot, home, smbVersion, mountOptions,
+//                fileMode, dirMode }.
+function mountCmd(settings, host, share) {
+    var mp = mountpointFor(settings.defaultMountRoot, settings.home, host, share);
+    var credId = safeComponent(host.id + "-" + share);
+    var script =
+        "set -u\n" +
+        "umask 077\n" +
+        "runtime=\"${XDG_RUNTIME_DIR:-/run/user/$(id -u)}/synology-nas\"\n" +
+        "mkdir -p \"$runtime\" || exit 1\n" +
+        "cf=\"$runtime/$1.cred\"\n" +
+        "trap 'rm -f \"$cf\"' EXIT INT TERM\n" +
+        "{ printf 'username=%s\\n' \"$3\"; printf 'domain=%s\\n' \"$4\"; " +
+        "printf 'password='; kwallet-query -f 'Synology NAS' -r \"$2\" " + WALLET + "; } > \"$cf\" || exit 1\n" +
+        "chmod 600 \"$cf\"\n" +
+        "exec pkexec " + HELPER + " mount \"$5\" \"$6\" \"$cf\" \"$7\" \"$8\" \"$9\" \"${10}\"\n";
+    var args = [
+        credId,                             // $1 cred file id
+        walletKey(host),                    // $2 wallet entry
+        host.username || "",                // $3
+        host.domain || "",                  // $4
+        unc(host, share),                   // $5 //host/share
+        mp,                                 // $6 mountpoint
+        host.vers || settings.smbVersion,   // $7 smb version
+        settings.mountOptions,              // $8 mount options
+        settings.fileMode,                  // $9 file mode
+        settings.dirMode                    // $10 dir mode
+    ];
+    return { cmd: shCmd(script, args), mountpoint: mp };
+}
+
+// Unmount a share (privileged helper via pkexec).
+function unmountCmd(mountpoint) {
+    return shCmd("exec pkexec " + HELPER + " unmount \"$1\"", [mountpoint]);
+}
+
+// Save a password to KWallet (used by the config page). kwallet-query reads the
+// secret from stdin; we feed it via printf from a positional param. The value
+// is in this process's argv for the brief write (unavoidable with a CLI-only
+// KWallet path) — see the security notes in the README.
+function savePasswordCmd(host, password) {
+    var script = "printf '%s' \"$2\" | kwallet-query -f 'Synology NAS' -w \"$1\" " + WALLET;
+    return shCmd(script, [walletKey(host), password]);
+}
+
+// Remove a host's stored password (best effort; overwrites with empty).
+function deletePasswordCmd(host) {
+    var script = "printf '' | kwallet-query -f 'Synology NAS' -w \"$1\" " + WALLET + " 2>/dev/null || true";
+    return shCmd(script, [walletKey(host)]);
+}
+
+/* ---- parsers ----------------------------------------------------------- */
+
+// Parse `smbclient -L -g` output into [{name, comment}], dropping admin shares.
+function parseShares(stdout) {
+    var shares = [];
+    var lines = (stdout || "").split("\n");
+    for (var i = 0; i < lines.length; ++i) {
+        var f = lines[i].split("|");
+        if (f.length >= 2 && f[0] === "Disk") {
+            var name = f[1];
+            if (name.length === 0 || /\$$/.test(name)) continue; // skip IPC$, print$, admin$
+            shares.push({ name: name, comment: f.length >= 3 ? f[2] : "" });
+        }
+    }
+    shares.sort(function (a, b) { return a.name.localeCompare(b.name); });
+    return shares;
+}
+
+// Parse `findmnt -rn TARGET,SOURCE` into a set-like object keyed by mountpoint.
+function parseMounted(stdout) {
+    var set = {};
+    var lines = (stdout || "").split("\n");
+    for (var i = 0; i < lines.length; ++i) {
+        var line = lines[i];
+        if (line.length === 0) continue;
+        var sp = line.indexOf(" ");
+        var target = sp === -1 ? line : line.substring(0, sp);
+        target = target.replace(/\\040/g, " ").replace(/\\011/g, "\t").replace(/\\134/g, "\\");
+        set[target] = true;
+    }
+    return set;
+}
+
+// Parse the hosts JSON config into an array (never throws).
+function parseHosts(json) {
+    try {
+        var v = JSON.parse(json || "[]");
+        return Array.isArray(v) ? v : [];
+    } catch (e) {
+        return [];
+    }
+}