rdjakovic/managing-tauri-plugin-permissions

Managing Tauri Plugin Permissions

Tauri's capability and permission system provides granular security control for desktop and mobile applications. This skill covers configuring capabilities for windows and platforms, using plugin permissions effectively, and writing custom plugin permissions.

Core Concepts

Capabilities

Capabilities are JSON configuration files that assign permissions to specific windows and platforms. They follow the principle of least privilege.

Location: src-tauri/capabilities/

Structure:

{
  "identifier": "capability-name",
  "description": "Human-readable purpose",
  "local": true,
  "windows": ["window-label"],
  "permissions": ["plugin:allow-action"],
  "platforms": ["linux", "windows", "macos", "android", "ios"]
}

Permission Levels

Permissions operate at two levels:

• Commands: Individual operations (e.g., allow-write-text-file)
• Scopes: Path-based restrictions defining accessible files/directories

Platform-Specific Capabilities

Targeting Platforms

Restrict capabilities to specific operating systems using the platforms field:

{
  "identifier": "desktop-fs-access",
  "description": "Filesystem access for desktop platforms",
  "windows": ["main"],
  "permissions": ["fs:allow-home-read"],
  "platforms": ["linux", "windows", "macos"]
}

Available platforms: linux, windows, macos, android, ios

Mobile-Only Capabilities

{
  "identifier": "mobile-camera",
  "description": "Camera access for mobile devices",
  "windows": ["main"],
  "permissions": ["camera:allow-capture"],
  "platforms": ["android", "ios"]
}

Window-Specific Capabilities

Configuring Multiple Windows

Define windows in tauri.conf.json:

{
  "windows": [
    {
      "label": "main",
      "title": "Main Window",
      "width": 800,
      "height": 600
    },
    {
      "label": "settings",
      "title": "Settings",
      "width": 400,
      "height": 300
    }
  ]
}

Assigning Capabilities to Windows

Create separate capability files for each window's needs:

src-tauri/capabilities/main-window.json:

{
  "identifier": "main-window-capabilities",
  "description": "Full access for main window",
  "local": true,
  "windows": ["main"],
  "permissions": [
    "fs:allow-home-read",
    "fs:allow-home-write",
    "dialog:allow-open",
    "dialog:allow-save"
  ]
}

src-tauri/capabilities/settings-window.json:

{
  "identifier": "settings-window-capabilities",
  "description": "Limited access for settings window",
  "local": true,
  "windows": ["settings"],
  "permissions": [
    "fs:allow-app-read",
    "fs:allow-app-write"
  ]
}

Shared Capabilities Across Windows

{
  "identifier": "shared-dialog",
  "description": "Dialog access for multiple windows",
  "local": true,
  "windows": ["main", "settings"],
  "permissions": ["dialog:allow-ask", "dialog:allow-message"]
}

Using Plugin Permissions

Default Permission Sets

Every plugin provides a default permission set with baseline access. Enable it with:

{
  "permissions": ["plugin-name:default"]
}

Finding Available Permissions

1. Official plugins: Check Tauri documentation's permission tables
2. Plugin source: Look in permissions/autogenerated directories
3. Community plugins: Check repository or crates.io page

Permission Identifier Format

plugin-name:permission-name

Examples:

• fs:allow-read
• fs:allow-write-text-file
• dialog:allow-open
• shell:allow-spawn

Configuring with Scopes

Restrict permissions to specific paths:

{
  "identifier": "default",
  "description": "Main window capabilities",
  "windows": ["main"],
  "permissions": [
    "fs:allow-write-text-file",
    {
      "identifier": "fs:allow-read",
      "allow": [{ "path": "$HOME/Documents/**" }]
    },
    {
      "identifier": "fs:allow-write",
      "allow": [{ "path": "$APP/**" }]
    }
  ]
}

Common Scope Variables

| Variable | Description | |----------|-------------| | $APP | Application data directory | | $HOME | User home directory | | $RESOURCE | Application resources | | $TEMP | Temporary directory | | $DESKTOP | User desktop | | $DOCUMENT | User documents | | $DOWNLOAD | User downloads |

Deny Permissions

Explicitly deny specific operations:

{
  "permissions": [
    "fs:default",
    "fs:deny-write-text-file"
  ]
}

Writing Custom Plugin Permissions

Plugin Structure

Create a plugin with the Tauri CLI:

cargo tauri plugin new my-plugin
cd tauri-plugin-my-plugin

Implementing Commands

src/commands.rs:

use tauri::{command, AppHandle, Runtime};

#[command]
pub(crate) async fn read_data<R: Runtime>(
    key: String,
    app: AppHandle<R>,
) -> Result<String, String> {
    // Implementation
    Ok(format!("Data for key: {}", key))
}

#[command]
pub(crate) async fn write_data<R: Runtime>(
    key: String,
    value: String,
    app: AppHandle<R>,
) -> Result<(), String> {
    // Implementation
    Ok(())
}

#[command]
pub(crate) async fn delete_data<R: Runtime>(
    key: String,
    app: AppHandle<R>,
) -> Result<(), String> {
    // Implementation
    Ok(())
}

Auto-Generating Permissions

src/build.rs:

const COMMANDS: &[&str] = &["read_data", "write_data", "delete_data"];

fn main() {
    tauri_plugin::Builder::new(COMMANDS)
        .global_api_script_path("./api-iife.js")
        .build();
}

This generates:

• allow-read-data / deny-read-data
• allow-write-data / deny-write-data
• allow-delete-data / deny-delete-data

Defining Default Permissions

permissions/default.toml:

"$schema" = "schemas/schema.json"

[default]
description = "Default permissions for my-plugin. Allows read operations only."
permissions = ["allow-read-data"]

Creating Permission Sets

permissions/read-write.toml:

"$schema" = "schemas/schema.json"

[[set]]
identifier = "read-write"
description = "Allows both read and write operations"
permissions = ["allow-read-data", "allow-write-data"]

permissions/full-access.toml:

"$schema" = "schemas/schema.json"

[[set]]
identifier = "full-access"
description = "Allows all operations including delete"
permissions = ["allow-read-data", "allow-write-data", "allow-delete-data"]

Registering Commands

src/lib.rs:

use tauri::{
    plugin::{Builder, TauriPlugin},
    Manager, Runtime,
};

mod commands;

pub fn init<R: Runtime>() -> TauriPlugin<R> {
    Builder::new("my-plugin")
        .invoke_handler(tauri::generate_handler![
            commands::read_data,
            commands::write_data,
            commands::delete_data,
        ])
        .build()
}

Frontend JavaScript Bindings

guest-js/index.ts:

import { invoke } from '@tauri-apps/api/core';

export async function readData(key: string): Promise<string> {
  return await invoke('plugin:my-plugin|read_data', { key });
}

export async function writeData(key: string, value: string): Promise<void> {
  return await invoke('plugin:my-plugin|write_data', { key, value });
}

export async function deleteData(key: string): Promise<void> {
  return await invoke('plugin:my-plugin|delete_data', { key });
}

Using Custom Plugin Permissions

In your application's capability file:

{
  "identifier": "default",
  "windows": ["main"],
  "permissions": [
    "my-plugin:default",
    "my-plugin:read-write",
    "my-plugin:allow-delete-data"
  ]
}

Complete Example: Cross-Platform App

src-tauri/capabilities/desktop.json:

{
  "$schema": "../gen/schemas/desktop-schema.json",
  "identifier": "desktop",
  "windows": ["main"],
  "platforms": ["linux", "windows", "macos"],
  "permissions": [
    "core:default",
    "fs:default",
    { "identifier": "fs:allow-read", "allow": [{ "path": "$HOME/Documents/**" }] },
    { "identifier": "fs:allow-write", "allow": [{ "path": "$APP/**" }] },
    "dialog:allow-open",
    "dialog:allow-save",
    "shell:allow-open"
  ]
}

src-tauri/capabilities/mobile.json:

{
  "identifier": "mobile",
  "windows": ["main"],
  "platforms": ["android", "ios"],
  "permissions": [
    "fs:allow-app-read",
    "fs:allow-app-write",
    "notification:default"
  ]
}

Best Practices

Security

1. Principle of least privilege: Grant only required permissions
2. Use scopes: Restrict file access to specific paths rather than broad permissions
3. Separate by window: Each window should have only the permissions it needs
4. Platform targeting: Avoid granting mobile permissions on desktop and vice versa

Organization

1. Organize by function: Group capabilities by feature area
2. Use descriptive identifiers: Make capability purposes clear
3. Document permissions: Include descriptions explaining why each permission is needed

Plugin Development

1. Minimal defaults: Default permission sets should be restrictive
2. Create permission sets: Offer tiered access levels (read-only, read-write, full)
3. Use auto-generation: Let Tauri generate allow/deny permissions for commands
4. Test permissions: Verify permission behavior with example applications

Troubleshooting

Permission Denied Errors

If you encounter permission errors:

1. Check capability file syntax (valid JSON)
2. Verify the window label matches your configuration
3. Confirm the permission identifier is correct
4. Check if a scope is required for path-based operations

Capability Not Applied

1. Ensure capability files are in src-tauri/capabilities/
2. Verify the windows array contains the correct window labels
3. Check platforms includes your target OS
4. Rebuild the application after capability changes

References

• Tauri Capabilities Documentation
• Using Plugin Permissions
• Writing Plugin Permissions
• Capability Reference