From 3be8b6dc34f00e40f2b085df91abcd18d64a503e Mon Sep 17 00:00:00 2001
From: Brandon Keiji <brandonkeiji@google.com>
Date: Tue, 13 May 2025 21:13:54 +0000
Subject: [PATCH] fix(sandbox): default to current user profile for
 debian/ubuntu env (#337)

---
 packages/cli/src/utils/sandbox.ts | 62 +++++++++++++++++++++++++++++--
 1 file changed, 58 insertions(+), 4 deletions(-)

diff --git a/packages/cli/src/utils/sandbox.ts b/packages/cli/src/utils/sandbox.ts
index b1605184..a70aced1 100644
--- a/packages/cli/src/utils/sandbox.ts
+++ b/packages/cli/src/utils/sandbox.ts
@@ -8,12 +8,67 @@ import { execSync, spawnSync, spawn } from 'node:child_process';
 import os from 'node:os';
 import path from 'node:path';
 import fs from 'node:fs';
+import { readFile } from 'node:fs/promises';
 import { quote } from 'shell-quote';
 import {
   USER_SETTINGS_DIR,
   SETTINGS_DIRECTORY_NAME,
 } from '../config/settings.js';
 
+/**
+ * Determines whether the sandbox container should be run with the current user's UID and GID.
+ * This is often necessary on Linux systems (especially Debian/Ubuntu based) when using
+ * rootful Docker without userns-remap configured, to avoid permission issues with
+ * mounted volumes.
+ *
+ * The behavior is controlled by the `SANDBOX_SET_UID_GID` environment variable:
+ * - If `SANDBOX_SET_UID_GID` is "1" or "true", this function returns `true`.
+ * - If `SANDBOX_SET_UID_GID` is "0" or "false", this function returns `false`.
+ * - If `SANDBOX_SET_UID_GID` is not set:
+ *   - On Debian/Ubuntu Linux, it defaults to `true`.
+ *   - On other OSes, or if OS detection fails, it defaults to `false`.
+ *
+ * For more context on running Docker containers as non-root, see:
+ * https://medium.com/redbubble/running-a-docker-container-as-a-non-root-user-7d2e00f8ee15
+ *
+ * @returns {Promise<boolean>} A promise that resolves to true if the current user's UID/GID should be used, false otherwise.
+ */
+async function shouldUseCurrentUserInSandbox(): Promise<boolean> {
+  const envVar = process.env.SANDBOX_SET_UID_GID?.toLowerCase().trim();
+
+  if (envVar === '1' || envVar === 'true') {
+    return true;
+  }
+  if (envVar === '0' || envVar === 'false') {
+    return false;
+  }
+
+  // If environment variable is not explicitly set, check for Debian/Ubuntu Linux
+  if (os.platform() === 'linux') {
+    try {
+      const osReleaseContent = await readFile('/etc/os-release', 'utf8');
+      if (
+        osReleaseContent.includes('ID=debian') ||
+        osReleaseContent.includes('ID=ubuntu') ||
+        osReleaseContent.match(/^ID_LIKE=.*debian.*/m) || // Covers derivatives
+        osReleaseContent.match(/^ID_LIKE=.*ubuntu.*/m) // Covers derivatives
+      ) {
+        console.log(
+          'INFO: Defaulting to use current user UID/GID for Debian/Ubuntu-based Linux.',
+        );
+        return true;
+      }
+    } catch (_err) {
+      // Silently ignore if /etc/os-release is not found or unreadable.
+      // The default (false) will be applied in this case.
+      console.warn(
+        'Warning: Could not read /etc/os-release to auto-detect Debian/Ubuntu for UID/GID default.',
+      );
+    }
+  }
+  return false; // Default to false if no other condition is met
+}
+
 // node.js equivalent of scripts/sandbox_command.sh
 export function sandbox_command(sandbox?: string | boolean): string {
   // note environment variable takes precedence over argument (from command line or settings)
@@ -388,10 +443,9 @@ export async function start_sandbox(sandbox: string) {
     args.push('--authfile', emptyAuthFilePath);
   }
 
-  // specify --user as "$(id -u):$(id -g)" if SANDBOX_SET_UID_GID is 1|true
-  // only necessary if user mapping is not handled by sandboxing setup on host
-  // (e.g. rootful docker on linux w/o userns-remap configured)
-  if (['1', 'true'].includes(process.env.SANDBOX_SET_UID_GID ?? '')) {
+  // Determine if the current user's UID/GID should be passed to the sandbox.
+  // See shouldUseCurrentUserInSandbox for more details.
+  if (await shouldUseCurrentUserInSandbox()) {
     const uid = execSync('id -u').toString().trim();
     const gid = execSync('id -g').toString().trim();
     args.push('--user', `${uid}:${gid}`);