client: move key management into separate module

and use api macro for methods and Kdf type

Signed-off-by: Wolfgang Bumiller <w.bumiller@proxmox.com>

src/bin/proxmox_backup_client/key.rs

@@ -0,0 +1,267 @@
+use std::path::PathBuf;
+
+use anyhow::{bail, Error};
+use chrono::{Local, TimeZone};
+use serde::{Deserialize, Serialize};
+use xdg::BaseDirectories;
+
+use proxmox::api::api;
+use proxmox::api::cli::{CliCommand, CliCommandMap};
+use proxmox::sys::linux::tty;
+use proxmox::tools::fs::{file_get_contents, replace_file, CreateOptions};
+
+use proxmox_backup::backup::{
+    encrypt_key_with_passphrase, load_and_decrypt_key, store_key_config, KeyConfig,
+};
+use proxmox_backup::tools;
+
+pub fn master_pubkey_path() -> Result<PathBuf, Error> {
+    let base = BaseDirectories::with_prefix("proxmox-backup")?;
+
+    // usually $HOME/.config/proxmox-backup/master-public.pem
+    let path = base.place_config_file("master-public.pem")?;
+
+    Ok(path)
+}
+
+pub fn default_encryption_key_path() -> Result<PathBuf, Error> {
+    let base = BaseDirectories::with_prefix("proxmox-backup")?;
+
+    // usually $HOME/.config/proxmox-backup/encryption-key.json
+    let path = base.place_config_file("encryption-key.json")?;
+
+    Ok(path)
+}
+
+pub fn get_encryption_key_password() -> Result<Vec<u8>, Error> {
+    // fixme: implement other input methods
+
+    use std::env::VarError::*;
+    match std::env::var("PBS_ENCRYPTION_PASSWORD") {
+        Ok(p) => return Ok(p.as_bytes().to_vec()),
+        Err(NotUnicode(_)) => bail!("PBS_ENCRYPTION_PASSWORD contains bad characters"),
+        Err(NotPresent) => {
+            // Try another method
+        }
+    }
+
+    // If we're on a TTY, query the user for a password
+    if tty::stdin_isatty() {
+        return Ok(tty::read_password("Encryption Key Password: ")?);
+    }
+
+    bail!("no password input mechanism available");
+}
+
+#[api(
+    default: "scrypt",
+)]
+#[derive(Clone, Copy, Debug, Deserialize, Serialize)]
+#[serde(rename_all = "kebab-case")]
+/// Key derivation function for password protected encryption keys.
+pub enum Kdf {
+    /// Do not encrypt the key.
+    None,
+
+    /// Encrypt they key with a password using SCrypt.
+    Scrypt,
+}
+
+impl Default for Kdf {
+    #[inline]
+    fn default() -> Self {
+        Kdf::Scrypt
+    }
+}
+
+#[api(
+    input: {
+        properties: {
+            kdf: {
+                type: Kdf,
+                optional: true,
+            },
+            path: {
+                description:
+                    "Output file. Without this the key will become the new default encryption key.",
+                optional: true,
+            }
+        },
+    },
+)]
+/// Create a new encryption key.
+fn create(kdf: Option<Kdf>, path: Option<String>) -> Result<(), Error> {
+    let path = match path {
+        Some(path) => PathBuf::from(path),
+        None => default_encryption_key_path()?,
+    };
+
+    let kdf = kdf.unwrap_or_default();
+
+    let key = proxmox::sys::linux::random_data(32)?;
+
+    match kdf {
+        Kdf::None => {
+            let created = Local.timestamp(Local::now().timestamp(), 0);
+
+            store_key_config(
+                &path,
+                false,
+                KeyConfig {
+                    kdf: None,
+                    created,
+                    modified: created,
+                    data: key,
+                },
+            )?;
+        }
+        Kdf::Scrypt => {
+            // always read passphrase from tty
+            if !tty::stdin_isatty() {
+                bail!("unable to read passphrase - no tty");
+            }
+
+            let password = tty::read_and_verify_password("Encryption Key Password: ")?;
+
+            let key_config = encrypt_key_with_passphrase(&key, &password)?;
+
+            store_key_config(&path, false, key_config)?;
+        }
+    }
+
+    Ok(())
+}
+
+#[api(
+    input: {
+        properties: {
+            kdf: {
+                type: Kdf,
+                optional: true,
+            },
+            path: {
+                description: "Key file. Without this the default key's password will be changed.",
+                optional: true,
+            }
+        },
+    },
+)]
+/// Change the encryption key's password.
+fn change_passphrase(kdf: Option<Kdf>, path: Option<String>) -> Result<(), Error> {
+    let path = match path {
+        Some(path) => PathBuf::from(path),
+        None => default_encryption_key_path()?,
+    };
+
+    let kdf = kdf.unwrap_or_default();
+
+    if !tty::stdin_isatty() {
+        bail!("unable to change passphrase - no tty");
+    }
+
+    let (key, created) = load_and_decrypt_key(&path, &get_encryption_key_password)?;
+
+    match kdf {
+        Kdf::None => {
+            let modified = Local.timestamp(Local::now().timestamp(), 0);
+
+            store_key_config(
+                &path,
+                true,
+                KeyConfig {
+                    kdf: None,
+                    created, // keep original value
+                    modified,
+                    data: key.to_vec(),
+                },
+            )?;
+        }
+        Kdf::Scrypt => {
+            let password = tty::read_and_verify_password("New Password: ")?;
+
+            let mut new_key_config = encrypt_key_with_passphrase(&key, &password)?;
+            new_key_config.created = created; // keep original value
+
+            store_key_config(&path, true, new_key_config)?;
+        }
+    }
+
+    Ok(())
+}
+
+#[api(
+    input: {
+        properties: {
+            path: {
+                description: "Path to the PEM formatted RSA public key.",
+            },
+        },
+    },
+)]
+/// Import an RSA public key used to put an encrypted version of the symmetric backup encryption
+/// key onto the backup server along with each backup.
+fn import_master_pubkey(path: String) -> Result<(), Error> {
+    let pem_data = file_get_contents(&path)?;
+
+    if let Err(err) = openssl::pkey::PKey::public_key_from_pem(&pem_data) {
+        bail!("Unable to decode PEM data - {}", err);
+    }
+
+    let target_path = master_pubkey_path()?;
+
+    replace_file(&target_path, &pem_data, CreateOptions::new())?;
+
+    println!("Imported public master key to {:?}", target_path);
+
+    Ok(())
+}
+
+#[api]
+/// Create an RSA public/private key pair used to put an encrypted version of the symmetric backup
+/// encryption key onto the backup server along with each backup.
+fn create_master_key() -> Result<(), Error> {
+    // we need a TTY to query the new password
+    if !tty::stdin_isatty() {
+        bail!("unable to create master key - no tty");
+    }
+
+    let rsa = openssl::rsa::Rsa::generate(4096)?;
+    let pkey = openssl::pkey::PKey::from_rsa(rsa)?;
+
+    let password = String::from_utf8(tty::read_and_verify_password("Master Key Password: ")?)?;
+
+    let pub_key: Vec<u8> = pkey.public_key_to_pem()?;
+    let filename_pub = "master-public.pem";
+    println!("Writing public master key to {}", filename_pub);
+    replace_file(filename_pub, pub_key.as_slice(), CreateOptions::new())?;
+
+    let cipher = openssl::symm::Cipher::aes_256_cbc();
+    let priv_key: Vec<u8> = pkey.private_key_to_pem_pkcs8_passphrase(cipher, password.as_bytes())?;
+
+    let filename_priv = "master-private.pem";
+    println!("Writing private master key to {}", filename_priv);
+    replace_file(filename_priv, priv_key.as_slice(), CreateOptions::new())?;
+
+    Ok(())
+}
+
+pub fn cli() -> CliCommandMap {
+    let key_create_cmd_def = CliCommand::new(&API_METHOD_CREATE)
+        .arg_param(&["path"])
+        .completion_cb("path", tools::complete_file_name);
+
+    let key_change_passphrase_cmd_def = CliCommand::new(&API_METHOD_CHANGE_PASSPHRASE)
+        .arg_param(&["path"])
+        .completion_cb("path", tools::complete_file_name);
+
+    let key_create_master_key_cmd_def = CliCommand::new(&API_METHOD_CREATE_MASTER_KEY);
+    let key_import_master_pubkey_cmd_def = CliCommand::new(&API_METHOD_IMPORT_MASTER_PUBKEY)
+        .arg_param(&["path"])
+        .completion_cb("path", tools::complete_file_name);
+
+    CliCommandMap::new()
+        .insert("create", key_create_cmd_def)
+        .insert("create-master-key", key_create_master_key_cmd_def)
+        .insert("import-master-pubkey", key_import_master_pubkey_cmd_def)
+        .insert("change-passphrase", key_change_passphrase_cmd_def)
+}