libnss-rs

Rust bindings for creating libnss modules.

Currently supports the following databases:

• passwd
• shadow
• group
• hosts

Getting started

• Create a new library

  cargo new nss_example --lib
  

• Change library type to cdylib in your Cargo.toml

  [lib]
  name = "nss_example"
  crate-type = [ "cdylib" ]
  

  *** NOTE *** The name of the crate itself is not important, however the library itself must follow the nss_xxx pattern.

• Add libnss to your Cargo.toml

  [dependencies]
  libc = "0.2.0"
  libnss = "0.8.0"
  

• Implement a passwd database

  use libnss::passwd::{PasswdHooks, Passwd};
  use libnss::libnss_passwd_hooks;
  
  struct ExamplePasswd;
  libnss_passwd_hooks!(example, ExamplePasswd);
  

  It is important that the first param of libnss_passwd_hooks is the name of your final library libnss_example.so.2

  impl PasswdHooks for HardcodedPasswd {
      fn get_all_entries() -> Vec<Passwd> {
          vec![
              Passwd {
                  name: "test".to_string(),
                  passwd: "x".to_string(),
                  uid: 1005,
                  gid: 1005,
                  gecos: "Test Account".to_string(),
                  dir: "/home/test".to_string(),
                  shell: "/bin/bash".to_string(),
              }
          ]
      }
  
      fn get_entry_by_uid(uid: libc::uid_t) -> Option<Passwd> {
          if uid == 1005 {
              return Some(Passwd {
                  name: "test".to_string(),
                  passwd: "x".to_string(),
                  uid: 1005,
                  gid: 1005,
                  gecos: "Test Account".to_string(),
                  dir: "/home/test".to_string(),
                  shell: "/bin/bash".to_string(),
              });
          }
  
          None
      }
  
      fn get_entry_by_name(name: String) -> Option<Passwd> {
          if name == "test" {
              return Some(Passwd {
                  name: "test".to_string(),
                  passwd: "x".to_string(),
                  uid: 1005,
                  gid: 1005,
                  gecos: "Test Account".to_string(),
                  dir: "/home/test".to_string(),
                  shell: "/bin/bash".to_string(),
              });
          }
  
          None
      }
  }
  

• Build

  cargo build --release
  

• Install the library

  cd target/release
  cp libnss_example.so libnss_example.so.2
  sudo install -m 0644 libnss_example.so.2 /lib
  sudo /sbin/ldconfig -n /lib /usr/lib
  

• Enable your nss module in /etc/nsswitch.conf eg:

  passwd:         example files systemd
  

  The name in here must follow the final library name libnss_example.so.2

• Look at the examples for more information