[pbs-devel] [PATCH v2 proxmox-backup 1/2] access: limit editing pam credentials to superuser

[Fabian Grünbichler]

On January 13, 2021 12:27 pm, Oguz Bektas wrote:
> modifying @pam users credentials should be only possible for root at pam,
> otherwise it can have unintended consequences.
> 
> Signed-off-by: Oguz Bektas <o.bektas at proxmox.com>
> ---
> v1->v2:
> * change error message to be more descriptive
> * remove empty line
> * create CachedUserInfo in the if-branch
> 
> 
>  src/api2/access/user.rs | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/src/api2/access/user.rs b/src/api2/access/user.rs
> index 484919bf..4c861c5f 100644
> --- a/src/api2/access/user.rs
> +++ b/src/api2/access/user.rs
> @@ -350,6 +350,7 @@ pub fn update_user(
>      email: Option<String>,
>      delete: Option<Vec<DeletableProperty>>,
>      digest: Option<String>,
> +    rpcenv: &mut dyn RpcEnvironment,
>  ) -> Result<(), Error> {
>  
>      let _lock = open_file_locked(user::USER_CFG_LOCKFILE, std::time::Duration::new(10, 0), true)?;
> @@ -392,7 +393,12 @@ pub fn update_user(
>      }
>  
>      if let Some(password) = password {
> +        let user_info = CachedUserInfo::new()?;
> +        let source_auth_id = rpcenv.get_auth_id().unwrap().parse()?;
>          let authenticator = crate::auth::lookup_authenticator(userid.realm())?;
> +        if userid.realm() == "pam" && !user_info.is_superuser(&source_auth_id) {
> +            bail!("only superuser can edit pam credentials!");
> +        }

1.) that code reads weird, authenticator should be declared and 
initialized after the check
2.) regular PAM users can now no longer self-service change their own password

>          authenticator.store_password(userid.name(), &password)?;
>      }
>  
> -- 
> 2.20.1
> 
> 
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> 
>