config: refactor secret sourcing

1 files changed, 280 insertions, 0 deletions

diff --git a/src/garage/secrets.rs b/src/garage/secrets.rs
new file mode 100644
index 00000000..c40c3cc9
--- /dev/null
+++ b/src/garage/secrets.rs
@@ -0,0 +1,280 @@
+use structopt::StructOpt;
+
+use garage_util::config::Config;
+use garage_util::error::Error;
+
+/// Structure for secret values or paths that are passed as CLI arguments or environment
+/// variables, instead of in the config file.
+#[derive(StructOpt, Debug, Default, Clone)]
+pub struct Secrets {
+	/// Skip permission check on files containing secrets
+	#[cfg(unix)]
+	#[structopt(
+		long = "allow-world-readable-secrets",
+		env = "GARAGE_ALLOW_WORLD_READABLE_SECRETS"
+	)]
+	pub allow_world_readable_secrets: Option<bool>,
+
+	/// RPC secret network key, used to replace rpc_secret in config.toml when running the
+	/// daemon or doing admin operations
+	#[structopt(short = "s", long = "rpc-secret", env = "GARAGE_RPC_SECRET")]
+	pub rpc_secret: Option<String>,
+
+	/// RPC secret network key, used to replace rpc_secret in config.toml and rpc-secret
+	/// when running the daemon or doing admin operations
+	#[structopt(long = "rpc-secret-file", env = "GARAGE_RPC_SECRET_FILE")]
+	pub rpc_secret_file: Option<String>,
+
+	/// Admin API authentication token, replaces admin.admin_token in config.toml when
+	/// running the Garage daemon
+	#[structopt(long = "admin-token", env = "GARAGE_ADMIN_TOKEN")]
+	pub admin_token: Option<String>,
+
+	/// Admin API authentication token file path, replaces admin.admin_token in config.toml
+	/// and admin-token when running the Garage daemon
+	#[structopt(long = "admin-token-file", env = "GARAGE_ADMIN_TOKEN_FILE")]
+	pub admin_token_file: Option<String>,
+
+	/// Metrics API authentication token, replaces admin.metrics_token in config.toml when
+	/// running the Garage daemon
+	#[structopt(long = "metrics-token", env = "GARAGE_METRICS_TOKEN")]
+	pub metrics_token: Option<String>,
+
+	/// Metrics API authentication token file path, replaces admin.metrics_token in config.toml
+	/// and metrics-token when running the Garage daemon
+	#[structopt(long = "metrics-token-file", env = "GARAGE_METRICS_TOKEN_FILE")]
+	pub metrics_token_file: Option<String>,
+}
+
+/// Single function to fill all secrets in the Config struct from their correct source (value
+/// from config or CLI param or env variable or read from a file specified in config or CLI
+/// param or env variable)
+pub fn fill_secrets(mut config: Config, secrets: Secrets) -> Result<Config, Error> {
+	let allow_world_readable = secrets
+		.allow_world_readable_secrets
+		.unwrap_or(config.allow_world_readable_secrets);
+
+	fill_secret(
+		&mut config.rpc_secret,
+		&config.rpc_secret_file,
+		&secrets.rpc_secret,
+		&secrets.rpc_secret_file,
+		"rpc_secret",
+		allow_world_readable,
+	)?;
+
+	fill_secret(
+		&mut config.admin.admin_token,
+		&config.admin.admin_token_file,
+		&secrets.admin_token,
+		&secrets.admin_token_file,
+		"admin.admin_token",
+		allow_world_readable,
+	)?;
+	fill_secret(
+		&mut config.admin.metrics_token,
+		&config.admin.metrics_token_file,
+		&secrets.metrics_token,
+		&secrets.metrics_token_file,
+		"admin.metrics_token",
+		allow_world_readable,
+	)?;
+
+	Ok(config)
+}
+
+fn fill_secret(
+	config_secret: &mut Option<String>,
+	config_secret_file: &Option<String>,
+	cli_secret: &Option<String>,
+	cli_secret_file: &Option<String>,
+	name: &'static str,
+	allow_world_readable: bool,
+) -> Result<(), Error> {
+	let cli_value = match (&cli_secret, &cli_secret_file) {
+		(Some(_), Some(_)) => {
+			return Err(format!("only one of `{}` and `{}_file` can be set", name, name).into());
+		}
+		(Some(secret), None) => Some(secret.to_string()),
+		(None, Some(file)) => Some(read_secret_file(file, allow_world_readable)?),
+		(None, None) => None,
+	};
+
+	if let Some(val) = cli_value {
+		if config_secret.is_some() || config_secret_file.is_some() {
+			debug!("Overriding secret `{}` using value specified using CLI argument or environnement variable.", name);
+		}
+
+		*config_secret = Some(val);
+	} else if let Some(file_path) = &config_secret_file {
+		if config_secret.is_some() {
+			return Err(format!("only one of `{}` and `{}_file` can be set", name, name).into());
+		}
+
+		*config_secret = Some(read_secret_file(file_path, allow_world_readable)?);
+	}
+
+	Ok(())
+}
+
+fn read_secret_file(file_path: &String, allow_world_readable: bool) -> Result<String, Error> {
+	if !allow_world_readable {
+		#[cfg(unix)]
+		{
+			use std::os::unix::fs::MetadataExt;
+			let metadata = std::fs::metadata(file_path)?;
+			if metadata.mode() & 0o077 != 0 {
+				return Err(format!("File {} is world-readable! (mode: 0{:o}, expected 0600)\nRefusing to start until this is fixed, or environment variable GARAGE_ALLOW_WORLD_READABLE_SECRETS is set to true.", file_path, metadata.mode()).into());
+			}
+		}
+	}
+
+	let secret_buf = std::fs::read_to_string(file_path)?;
+
+	// trim_end: allows for use case such as `echo "$(openssl rand -hex 32)" > somefile`.
+	//           also editors sometimes add a trailing newline
+	Ok(String::from(secret_buf.trim_end()))
+}
+
+#[cfg(test)]
+mod tests {
+	use std::fs::File;
+	use std::io::Write;
+
+	use garage_util::config::read_config;
+	use garage_util::error::Error;
+
+	use super::*;
+
+	#[test]
+	fn test_rpc_secret_file_works() -> Result<(), Error> {
+		let path_secret = mktemp::Temp::new_file()?;
+		let mut file_secret = File::create(path_secret.as_path())?;
+		writeln!(file_secret, "foo")?;
+		drop(file_secret);
+
+		let path_config = mktemp::Temp::new_file()?;
+		let mut file_config = File::create(path_config.as_path())?;
+		let path_secret_path = path_secret.as_path();
+		writeln!(
+			file_config,
+			r#"
+			metadata_dir = "/tmp/garage/meta"
+			data_dir = "/tmp/garage/data"
+			replication_mode = "3"
+			rpc_bind_addr = "[::]:3901"
+			rpc_secret_file = "{}"
+
+			[s3_api]
+			s3_region = "garage"
+			api_bind_addr = "[::]:3900"
+			"#,
+			path_secret_path.display()
+		)?;
+		drop(file_config);
+
+		// Second configuration file, same as previous one
+		// except it allows world-readable secrets.
+		let path_config_allow_world_readable = mktemp::Temp::new_file()?;
+		let mut file_config_allow_world_readable =
+			File::create(path_config_allow_world_readable.as_path())?;
+		writeln!(
+			file_config_allow_world_readable,
+			r#"
+			metadata_dir = "/tmp/garage/meta"
+			data_dir = "/tmp/garage/data"
+			replication_mode = "3"
+			rpc_bind_addr = "[::]:3901"
+			rpc_secret_file = "{}"
+			allow_world_readable_secrets = true
+
+			[s3_api]
+			s3_region = "garage"
+			api_bind_addr = "[::]:3900"
+			"#,
+			path_secret_path.display()
+		)?;
+		drop(file_config_allow_world_readable);
+
+		let config = read_config(path_config.to_path_buf())?;
+		let config = fill_secrets(config, Secrets::default())?;
+		assert_eq!("foo", config.rpc_secret.unwrap());
+
+		#[cfg(unix)]
+		{
+			// Check non world-readable secrets config
+
+			let secrets_allow_world_readable = Secrets {
+				allow_world_readable_secrets: Some(true),
+				..Default::default()
+			};
+			let secrets_no_allow_world_readable = Secrets {
+				allow_world_readable_secrets: Some(false),
+				..Default::default()
+			};
+
+			use std::os::unix::fs::PermissionsExt;
+			let metadata = std::fs::metadata(&path_secret_path)?;
+			let mut perm = metadata.permissions();
+			perm.set_mode(0o660);
+			std::fs::set_permissions(&path_secret_path, perm)?;
+
+			// Config file that just specifies the path
+			let config = read_config(path_config.to_path_buf())?;
+			assert!(fill_secrets(config, Secrets::default()).is_err());
+
+			let config = read_config(path_config.to_path_buf())?;
+			assert!(fill_secrets(config, secrets_allow_world_readable.clone()).is_ok());
+
+			let config = read_config(path_config.to_path_buf())?;
+			assert!(fill_secrets(config, secrets_no_allow_world_readable.clone()).is_err());
+
+			// Config file that also specifies to allow world_readable_secrets
+			let config = read_config(path_config_allow_world_readable.to_path_buf())?;
+			assert!(fill_secrets(config, Secrets::default()).is_ok());
+
+			let config = read_config(path_config_allow_world_readable.to_path_buf())?;
+			assert!(fill_secrets(config, secrets_allow_world_readable).is_ok());
+
+			let config = read_config(path_config_allow_world_readable.to_path_buf())?;
+			assert!(fill_secrets(config, secrets_no_allow_world_readable).is_err());
+		}
+
+		drop(path_secret);
+		drop(path_config);
+		drop(path_config_allow_world_readable);
+
+		Ok(())
+	}
+
+	#[test]
+	fn test_rcp_secret_and_rpc_secret_file_cannot_be_set_both() -> Result<(), Error> {
+		let path_config = mktemp::Temp::new_file()?;
+		let mut file_config = File::create(path_config.as_path())?;
+		writeln!(
+			file_config,
+			r#"
+			metadata_dir = "/tmp/garage/meta"
+			data_dir = "/tmp/garage/data"
+			replication_mode = "3"
+			rpc_bind_addr = "[::]:3901"
+			rpc_secret= "dummy"
+			rpc_secret_file = "dummy"
+
+			[s3_api]
+			s3_region = "garage"
+			api_bind_addr = "[::]:3900"
+			"#
+		)?;
+		let config = read_config(path_config.to_path_buf())?;
+		assert_eq!(
+			"only one of `rpc_secret` and `rpc_secret_file` can be set",
+			fill_secrets(config, Secrets::default())
+				.unwrap_err()
+				.to_string()
+		);
+		drop(path_config);
+		drop(file_config);
+		Ok(())
+	}
+}