[pbs-devel] [PATCH v3 proxmox-backup 1/2] access: limit editing pam credentials to superuser

[pbs-devel] [PATCH v3 proxmox-backup 1/2] access: limit editing pam credentials to superuser

[Oguz Bektas]

modifying @pam users credentials should be only possible for root@pam,
otherwise it can have unintended consequences.

also enforce the same limit on user creation (except self_service check,
since it makes no sense during user creation)

Signed-off-by: Oguz Bektas <o.bektas@proxmox.com>
---
v2->v3:
* apply restrictions for 'create_user' as well
* make if condition more readable with variables
* fix issue with regular pam users being unable to edit their own
passwords (self_service)


 src/api2/access/user.rs | 25 +++++++++++++++++++++----
 1 file changed, 21 insertions(+), 4 deletions(-)

diff --git a/src/api2/access/user.rs b/src/api2/access/user.rs
index 484919bf..d9458524 100644
--- a/src/api2/access/user.rs
+++ b/src/api2/access/user.rs
@@ -218,7 +218,11 @@ pub fn list_users(
     },
 )]
 /// Create new user.
-pub fn create_user(password: Option<String>, param: Value) -> Result<(), Error> {
+pub fn create_user(
+    password: Option<String>,
+    param: Value,
+    rpcenv: &mut dyn RpcEnvironment
+) -> Result<(), Error> {
 
     let _lock = open_file_locked(user::USER_CFG_LOCKFILE, std::time::Duration::new(10, 0), true)?;
 
@@ -230,14 +234,19 @@ pub fn create_user(password: Option<String>, param: Value) -> Result<(), Error>
         bail!("user '{}' already exists.", user.userid);
     }
 
-    let authenticator = crate::auth::lookup_authenticator(&user.userid.realm())?;
-
     config.set_data(user.userid.as_str(), "user", &user)?;
 
     user::save_config(&config)?;
 
     if let Some(password) = password {
-        authenticator.store_password(user.userid.name(), &password)?;
+        let user_info = CachedUserInfo::new()?;
+        let current_auth_id: Authid = rpcenv.get_auth_id().unwrap().parse()?;
+        let target_realm = &user.userid.realm();
+        if *target_realm == "pam" && !user_info.is_superuser(&current_auth_id) {
+            bail!("only superuser can edit pam credentials!");
+        }
+        let authenticator = crate::auth::lookup_authenticator(target_realm)?;
+        authenticator.store_password(&user.userid.name(), &password)?;
     }
 
     Ok(())
@@ -350,6 +359,7 @@ 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)?;
@@ -392,6 +402,13 @@ pub fn update_user(
     }
 
     if let Some(password) = password {
+        let user_info = CachedUserInfo::new()?;
+        let current_auth_id: Authid = rpcenv.get_auth_id().unwrap().parse()?;
+        let self_service = current_auth_id.user() == &userid;
+        let target_realm = userid.realm();
+        if !self_service && target_realm == "pam" && !user_info.is_superuser(&current_auth_id) {
+            bail!("only superuser can edit pam credentials!");
+        }
         let authenticator = crate::auth::lookup_authenticator(userid.realm())?;
         authenticator.store_password(userid.name(), &password)?;
     }
-- 
2.20.1

[pbs-devel] [PATCH v3 proxmox-backup 2/2] access: restrict password changes on @pam realm to superuser

[Oguz Bektas]

for behavior consistency with `update_user`

Signed-off-by: Oguz Bektas <o.bektas@proxmox.com>
---
v2->v3:
* slightly change description s/Anybody/Everybody


 src/api2/access.rs | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/src/api2/access.rs b/src/api2/access.rs
index 8866c944..61d0f74e 100644
--- a/src/api2/access.rs
+++ b/src/api2/access.rs
@@ -245,7 +245,7 @@ fn create_ticket(
         },
     },
     access: {
-        description: "Anybody is allowed to change there own password. In addition, users with 'Permissions:Modify' privilege may change any password.",
+        description: "Everybody is allowed to change their own password. In addition, users with 'Permissions:Modify' privilege may change any password on @pbs realm.",
         permission: &Permission::Anybody,
     },
 )]
@@ -271,17 +271,16 @@ fn change_password(
 
     let mut allowed = userid == *current_user;
 
-    if current_user == "root@pam" {
-        allowed = true;
-    }
-
     if !allowed {
         let user_info = CachedUserInfo::new()?;
         let privs = user_info.lookup_privs(&current_auth, &[]);
-        if (privs & PRIV_PERMISSIONS_MODIFY) != 0 {
+        if user_info.is_superuser(&current_auth) {
             allowed = true;
         }
-    }
+        if (privs & PRIV_PERMISSIONS_MODIFY) != 0 && userid.realm() != "pam" {
+            allowed = true;
+        }
+    };
 
     if !allowed {
         bail!("you are not authorized to change the password.");
-- 
2.20.1

[pbs-devel] applied: [PATCH v3 proxmox-backup 2/2] access: restrict password changes on @pam realm to superuser

[Fabian Grünbichler]

On January 13, 2021 5:26 pm, Oguz Bektas wrote:
> for behavior consistency with `update_user`
> 
> Signed-off-by: Oguz Bektas <o.bektas@proxmox.com>
> ---
> v2->v3:
> * slightly change description s/Anybody/Everybody
> 
> 
>  src/api2/access.rs | 13 ++++++-------
>  1 file changed, 6 insertions(+), 7 deletions(-)
> 
> diff --git a/src/api2/access.rs b/src/api2/access.rs
> index 8866c944..61d0f74e 100644
> --- a/src/api2/access.rs
> +++ b/src/api2/access.rs
> @@ -245,7 +245,7 @@ fn create_ticket(
>          },
>      },
>      access: {
> -        description: "Anybody is allowed to change there own password. In addition, users with 'Permissions:Modify' privilege may change any password.",
> +        description: "Everybody is allowed to change their own password. In addition, users with 'Permissions:Modify' privilege may change any password on @pbs realm.",
>          permission: &Permission::Anybody,
>      },
>  )]
> @@ -271,17 +271,16 @@ fn change_password(
>  
>      let mut allowed = userid == *current_user;
>  
> -    if current_user == "root@pam" {
> -        allowed = true;
> -    }
> -
>      if !allowed {
>          let user_info = CachedUserInfo::new()?;
>          let privs = user_info.lookup_privs(&current_auth, &[]);
> -        if (privs & PRIV_PERMISSIONS_MODIFY) != 0 {
> +        if user_info.is_superuser(&current_auth) {
>              allowed = true;
>          }
> -    }
> +        if (privs & PRIV_PERMISSIONS_MODIFY) != 0 && userid.realm() != "pam" {
> +            allowed = true;
> +        }
> +    };
>  
>      if !allowed {
>          bail!("you are not authorized to change the password.");
> -- 
> 2.20.1
> 
> 
> _______________________________________________
> pbs-devel mailing list
> pbs-devel@lists.proxmox.com
> https://lists.proxmox.com/cgi-bin/mailman/listinfo/pbs-devel
> 
> 
> 

[pbs-devel] applied: [PATCH v3 proxmox-backup 1/2] access: limit editing pam credentials to superuser

[Fabian Grünbichler]

with fixup removing unnecessary ref/deref and moving the realm lookup 
back before saving the config, as it is our safeguard against bogus 
realms:

diff --git a/src/api2/access/user.rs b/src/api2/access/user.rs
index d9458524..f03389f8 100644
--- a/src/api2/access/user.rs
+++ b/src/api2/access/user.rs
@@ -236,17 +236,20 @@ pub fn create_user(
 
     config.set_data(user.userid.as_str(), "user", &user)?;
 
+    let realm = user.userid.realm();
+
+    // Fails if realm does not exist!
+    let authenticator = crate::auth::lookup_authenticator(realm)?;
+
     user::save_config(&config)?;
 
     if let Some(password) = password {
         let user_info = CachedUserInfo::new()?;
         let current_auth_id: Authid = rpcenv.get_auth_id().unwrap().parse()?;
-        let target_realm = &userZZ.userid.realm();
-        if *target_realm == "pam" && !user_info.is_superuser(&current_auth_id) {
+        if realm == "pam" && !user_info.is_superuser(&current_auth_id) {
             bail!("only superuser can edit pam credentials!");
         }
-        let authenticator = crate::auth::lookup_authenticator(target_realm)?;
-        authenticator.store_password(&user.userid.name(), &password)?;
+        authenticator.store_password(user.userid.name(), &password)?;
     }
 
     Ok(())

On January 13, 2021 5:26 pm, Oguz Bektas wrote:
> modifying @pam users credentials should be only possible for root@pam,
> otherwise it can have unintended consequences.
> 
> also enforce the same limit on user creation (except self_service check,
> since it makes no sense during user creation)
> 
> Signed-off-by: Oguz Bektas <o.bektas@proxmox.com>
> ---
> v2->v3:
> * apply restrictions for 'create_user' as well
> * make if condition more readable with variables
> * fix issue with regular pam users being unable to edit their own
> passwords (self_service)
> 
> 
>  src/api2/access/user.rs | 25 +++++++++++++++++++++----
>  1 file changed, 21 insertions(+), 4 deletions(-)
> 
> diff --git a/src/api2/access/user.rs b/src/api2/access/user.rs
> index 484919bf..d9458524 100644
> --- a/src/api2/access/user.rs
> +++ b/src/api2/access/user.rs
> @@ -218,7 +218,11 @@ pub fn list_users(
>      },
>  )]
>  /// Create new user.
> -pub fn create_user(password: Option<String>, param: Value) -> Result<(), Error> {
> +pub fn create_user(
> +    password: Option<String>,
> +    param: Value,
> +    rpcenv: &mut dyn RpcEnvironment
> +) -> Result<(), Error> {
>  
>      let _lock = open_file_locked(user::USER_CFG_LOCKFILE, std::time::Duration::new(10, 0), true)?;
>  
> @@ -230,14 +234,19 @@ pub fn create_user(password: Option<String>, param: Value) -> Result<(), Error>
>          bail!("user '{}' already exists.", user.userid);
>      }
>  
> -    let authenticator = crate::auth::lookup_authenticator(&user.userid.realm())?;
> -
>      config.set_data(user.userid.as_str(), "user", &user)?;
>  
>      user::save_config(&config)?;
>  
>      if let Some(password) = password {
> -        authenticator.store_password(user.userid.name(), &password)?;
> +        let user_info = CachedUserInfo::new()?;
> +        let current_auth_id: Authid = rpcenv.get_auth_id().unwrap().parse()?;
> +        let target_realm = &user.userid.realm();
> +        if *target_realm == "pam" && !user_info.is_superuser(&current_auth_id) {
> +            bail!("only superuser can edit pam credentials!");
> +        }
> +        let authenticator = crate::auth::lookup_authenticator(target_realm)?;
> +        authenticator.store_password(&user.userid.name(), &password)?;
>      }
>  
>      Ok(())
> @@ -350,6 +359,7 @@ 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)?;
> @@ -392,6 +402,13 @@ pub fn update_user(
>      }
>  
>      if let Some(password) = password {
> +        let user_info = CachedUserInfo::new()?;
> +        let current_auth_id: Authid = rpcenv.get_auth_id().unwrap().parse()?;
> +        let self_service = current_auth_id.user() == &userid;
> +        let target_realm = userid.realm();
> +        if !self_service && target_realm == "pam" && !user_info.is_superuser(&current_auth_id) {
> +            bail!("only superuser can edit pam credentials!");
> +        }
>          let authenticator = crate::auth::lookup_authenticator(userid.realm())?;
>          authenticator.store_password(userid.name(), &password)?;
>      }
> -- 
> 2.20.1
> 
> 
> _______________________________________________
> pbs-devel mailing list
> pbs-devel@lists.proxmox.com
> https://lists.proxmox.com/cgi-bin/mailman/listinfo/pbs-devel
> 
> 
>