[pbs-devel] [PATCH proxmox-backup 10/12] auth: upgrade hashes on user log in

[Stefan Sterz <s.sterz@proxmox.com>]

if a users password is not hashed with the latest password hashing
function, re-hash the password with the newest hashing function. we
can only do this on login and after the password has been validated,
as this is the only point at which we have access to the plain text
password and also know that it matched the original password.

Signed-off-by: Stefan Sterz <s.sterz@proxmox.com>
---
 src/auth.rs | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/src/auth.rs b/src/auth.rs
index c89314f5..3379577f 100644
--- a/src/auth.rs
+++ b/src/auth.rs
@@ -28,20 +28,30 @@ pub const TERM_PREFIX: &str = "PBSTERM";
 
 struct PbsAuthenticator;
 
-const SHADOW_CONFIG_FILENAME: &str = configdir!("/shadow.json");
+pub(crate) const SHADOW_CONFIG_FILENAME: &str = configdir!("/shadow.json");
 
 impl Authenticator for PbsAuthenticator {
     fn authenticate_user<'a>(
-        &self,
+        &'a self,
         username: &'a UsernameRef,
         password: &'a str,
-        _client_ip: Option<&'a IpAddr>,
+        client_ip: Option<&'a IpAddr>,
     ) -> Pin<Box<dyn Future<Output = Result<(), Error>> + Send + 'a>> {
         Box::pin(async move {
             let data = proxmox_sys::fs::file_get_json(SHADOW_CONFIG_FILENAME, Some(json!({})))?;
             match data[username.as_str()].as_str() {
                 None => bail!("no password set"),
-                Some(enc_password) => proxmox_sys::crypt::verify_crypt_pw(password, enc_password)?,
+                Some(enc_password) => {
+                    proxmox_sys::crypt::verify_crypt_pw(password, enc_password)?;
+
+                    // if the password hash is not based on the current hashing function (as
+                    // identified by its prefix), rehash the password.
+                    if !enc_password.starts_with(proxmox_sys::crypt::HASH_PREFIX) {
+                        // ignore errors here, we already authenticated the user, re-hashing the
+                        // password should not prevent them from logging in.
+                        let _ = self.store_password(username, password, client_ip);
+                    }
+                }
             }
             Ok(())
         })
-- 
2.39.2