[pbs-devel] applied: [PATCH proxmox-backup] auth: add locking to `PbsAuthenticator` to avoid race conditions

[Wolfgang Bumiller <w.bumiller@proxmox.com>]

applied, thanks

On Thu, May 23, 2024 at 01:25:59PM GMT, Shannon Sterz wrote:
> currently we don't lock the shadow file when removing or storing a
> password. by adding locking here we avoid a situation where storing
> and/or removing a password concurrently could lead to a race
> condition. in this scenario it is possible that a password isn't
> persisted or a password isn't removed. we already do this for
> the "token.shadow" file, so just use the same mechanism here.
> 
> Signed-off-by: Shannon Sterz <s.sterz@proxmox.com>
> ---
>  src/auth.rs | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/src/auth.rs b/src/auth.rs
> index 21468d4b..5134e41e 100644
> --- a/src/auth.rs
> +++ b/src/auth.rs
> @@ -9,6 +9,7 @@ use std::pin::Pin;
>  use anyhow::{bail, Error};
>  use futures::Future;
>  use once_cell::sync::{Lazy, OnceCell};
> +use pbs_config::open_backup_lockfile;
>  use proxmox_router::http_bail;
>  use serde_json::json;
>  
> @@ -31,6 +32,7 @@ pub const TERM_PREFIX: &str = "PBSTERM";
>  struct PbsAuthenticator;
>  
>  pub(crate) const SHADOW_CONFIG_FILENAME: &str = configdir!("/shadow.json");
> +pub(crate) const SHADOW_LOCK_FILENAME: &str = configdir!("/shadow.json.lock");
>  
>  impl Authenticator for PbsAuthenticator {
>      fn authenticate_user<'a>(
> @@ -69,6 +71,8 @@ impl Authenticator for PbsAuthenticator {
>          _client_ip: Option<&IpAddr>,
>      ) -> Result<(), Error> {
>          let enc_password = proxmox_sys::crypt::encrypt_pw(password)?;
> +
> +        let _guard = open_backup_lockfile(SHADOW_LOCK_FILENAME, None, true);
>          let mut data = proxmox_sys::fs::file_get_json(SHADOW_CONFIG_FILENAME, Some(json!({})))?;
>          data[username.as_str()] = enc_password.into();
>  
> @@ -85,6 +89,8 @@ impl Authenticator for PbsAuthenticator {
>      }
>  
>      fn remove_password(&self, username: &UsernameRef) -> Result<(), Error> {
> +        let _guard = open_backup_lockfile(SHADOW_LOCK_FILENAME, None, true);
> +
>          let mut data = proxmox_sys::fs::file_get_json(SHADOW_CONFIG_FILENAME, Some(json!({})))?;
>          if let Some(map) = data.as_object_mut() {
>              map.remove(username.as_str());
> -- 
> 2.39.2


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