feat: allow command-specific restrictions for ShellTool (#2605)

docs/cli/configuration.md

@@ -65,14 +65,17 @@ In addition to a project settings file, a project's `.gemini` directory can cont
     ```
 
 - **`coreTools`** (array of strings):
-  - **Description:** Allows you to specify a list of core tool names that should be made available to the model. This can be used to restrict the set of built-in tools. See [Built-in Tools](../core/tools-api.md#built-in-tools) for a list of core tools.
+  - **Description:** Allows you to specify a list of core tool names that should be made available to the model. This can be used to restrict the set of built-in tools. See [Built-in Tools](../core/tools-api.md#built-in-tools) for a list of core tools. You can also specify command-specific restrictions for tools that support it, like the `ShellTool`. For example, `"coreTools": ["ShellTool(ls -l)"]` will only allow the `ls -l` command to be executed.
   - **Default:** All tools available for use by the Gemini model.
-  - **Example:** `"coreTools": ["ReadFileTool", "GlobTool", "SearchText"]`.
+  - **Example:** `"coreTools": ["ReadFileTool", "GlobTool", "ShellTool(ls)"]`.
 
 - **`excludeTools`** (array of strings):
-  - **Description:** Allows you to specify a list of core tool names that should be excluded from the model. A tool listed in both `excludeTools` and `coreTools` is excluded.
+  - **Description:** Allows you to specify a list of core tool names that should be excluded from the model. A tool listed in both `excludeTools` and `coreTools` is excluded. You can also specify command-specific restrictions for tools that support it, like the `ShellTool`. For example, `"excludeTools": ["ShellTool(rm -rf)"]` will block the `rm -rf` command.
   - **Default**: No tools excluded.
   - **Example:** `"excludeTools": ["run_shell_command", "findFiles"]`.
+  - **Security Note:** Command-specific restrictions in
+    `excludeTools` for `run_shell_command` are based on simple string matching and can be easily bypassed. This feature is **not a security mechanism** and should not be relied upon to safely execute untrusted code. It is recommended to use `coreTools` to explicitly select commands
+    that can be executed.
 
 - **`autoAccept`** (boolean):
   - **Description:** Controls whether the CLI automatically accepts and executes tool calls that are considered safe (e.g., read-only operations) without explicit user confirmation. If set to `true`, the CLI will bypass the confirmation prompt for tools deemed safe.

docs/tools/shell.md

@@ -59,3 +59,105 @@ run_shell_command(command="npm run dev &", description="Start development server
 - **Interactive commands:** Avoid commands that require interactive user input, as this can cause the tool to hang. Use non-interactive flags if available (e.g., `npm init -y`).
 - **Error handling:** Check the `Stderr`, `Error`, and `Exit Code` fields to determine if a command executed successfully.
 - **Background processes:** When a command is run in the background with `&`, the tool will return immediately and the process will continue to run in the background. The `Background PIDs` field will contain the process ID of the background process.
+
+## Command Restrictions
+
+You can restrict the commands that can be executed by the `run_shell_command` tool by using the `coreTools` and `excludeTools` settings in your configuration file.
+
+- `coreTools`: If you want to restrict the `run_shell_command` tool to a specific set of commands, you can add entries to the `coreTools` list in the format `ShellTool(<command>)`. For example, `"coreTools": ["ShellTool(ls -l)"]` will only allow the `ls -l` command to be executed. If you include `ShellTool` as a general entry in the `coreTools` list, it will act as a wildcard and allow any command to be executed, even if you have other specific commands in the list.
+- `excludeTools`: If you want to block specific commands, you can add entries to the `excludeTools` list in the format `ShellTool(<command>)`. For example, `"excludeTools": ["ShellTool(rm -rf /)"]` will block the `rm -rf /` command.
+
+### Command Restriction Examples
+
+Here are some examples of how to use the `coreTools` and `excludeTools` settings to control which commands can be executed.
+
+**Allow only specific commands**
+
+To allow only `ls -l` and `git status`, and block all other commands:
+
+```json
+{
+  "coreTools": ["ShellTool(ls -l)", "ShellTool(git status)"]
+}
+```
+
+- `ls -l`: Allowed
+- `git status`: Allowed
+- `npm install`: Blocked
+
+**Block specific commands**
+
+To block `rm -rf /` and `npm install`, and allow all other commands:
+
+```json
+{
+  "excludeTools": ["ShellTool(rm -rf /)", "ShellTool(npm install)"]
+}
+```
+
+- `rm -rf /`: Blocked
+- `npm install`: Blocked
+- `ls -l`: Allowed
+
+**Allow all commands**
+
+To allow any command to be executed, you can use the `ShellTool` wildcard in `coreTools`:
+
+```json
+{
+  "coreTools": ["ShellTool"]
+}
+```
+
+- `ls -l`: Allowed
+- `npm install`: Allowed
+- `any other command`: Allowed
+
+**Wildcard with specific allowed commands**
+
+If you include the `ShellTool` wildcard along with specific commands, the wildcard takes precedence, and all commands are allowed.
+
+```json
+{
+  "coreTools": ["ShellTool", "ShellTool(ls -l)"]
+}
+```
+
+- `ls -l`: Allowed
+- `npm install`: Allowed
+- `any other command`: Allowed
+
+**Wildcard with a blocklist**
+
+You can use the `ShellTool` wildcard to allow all commands, while still blocking specific commands using `excludeTools`.
+
+```json
+{
+  "coreTools": ["ShellTool"],
+  "excludeTools": ["ShellTool(rm -rf /)"]
+}
+```
+
+- `rm -rf /`: Blocked
+- `ls -l`: Allowed
+- `npm install`: Allowed
+
+**Block all shell commands**
+
+To block all shell commands, you can add the `ShellTool` wildcard to `excludeTools`:
+
+```json
+{
+  "excludeTools": ["ShellTool"]
+}
+```
+
+- `ls -l`: Blocked
+- `npm install`: Blocked
+- `any other command`: Blocked
+
+## Security Note for `excludeTools`
+
+Command-specific restrictions in
+`excludeTools` for `run_shell_command` are based on simple string matching and can be easily bypassed. This feature is **not a security mechanism** and should not be relied upon to safely execute untrusted code. It is recommended to use `coreTools` to explicitly select commands
+that can be executed.