petbox 0.1.0

a lightweight unprivliged namespace container tool
Documentation 
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use std::{
    fs::{self, DirBuilder},
    io::{self, BufRead},
    path::{Path, PathBuf},
};
use unshare_petbox::{Command, GidMap, Namespace, UidMap};

use thiserror::Error;

#[derive(Debug)]
struct SubXidMap {
    xid: u32,
    subxid: u32,
    count: u32,
}

fn get_subxid(path: &Path) -> Vec<SubXidMap> {
    let mut mapvec = Vec::new();
    let t = fs::File::open(path).unwrap();
    for i in io::BufReader::new(t).lines() {
        let mut map = SubXidMap {
            xid: 0,
            subxid: 0,
            count: 0,
        };
        let i = i.unwrap();
        trace!("{:?}", &i);
        let v: Vec<&str> = i.split(":").collect();

        let u = v[0].parse::<u32>();
        map.xid = match u {
            Ok(u) => u,
            Err(_) => nix::unistd::User::from_name(v[0])
                .unwrap()
                .unwrap()
                .uid
                .into(),
        };

        map.subxid = v[1].parse::<u32>().unwrap();
        map.count = v[2].parse::<u32>().unwrap();
        trace!("{:#?}", map);
        mapvec.push(map);
    }
    mapvec
}

fn get_current_subuidmap() -> SubXidMap {
    let v = get_subxid(Path::new("/etc/subuid"));
    let mut m: Option<SubXidMap> = None;
    for i in v {
        if i.xid == nix::unistd::getuid().into() {
            m = Some(i);
        }
    }
    m.unwrap()
}

fn gen_uidmap() -> Vec<UidMap> {
    let mut mapvec = Vec::new();
    let subuidmap = get_current_subuidmap();
    trace!("subuidmap for current user:");
    trace!("{:#?}", subuidmap);
    mapvec.push(UidMap {
        inside_uid: subuidmap.xid,
        outside_uid: subuidmap.xid,
        count: 1,
    }); // Map for current user inside the container
    mapvec.push(UidMap {
        inside_uid: 0,
        outside_uid: subuidmap.subxid,
        count: 1000,
    });
    mapvec
}

fn gen_gidmap() -> Vec<GidMap> {
    let mut mapvec = Vec::new();
    let subuidmap = get_current_subuidmap();
    trace!("subuidmap for current user:");
    trace!("{:#?}", subuidmap);
    mapvec.push(GidMap {
        inside_gid: subuidmap.xid,
        outside_gid: subuidmap.xid,
        count: 1,
    }); // Map for current user inside the container
    mapvec.push(GidMap {
        inside_gid: 0,
        outside_gid: subuidmap.subxid,
        count: 1000,
    });
    mapvec
}

#[derive(Error, Debug)]
pub enum RootfsError {
    #[error("cannot unshare namespace: `{0}`")]
    UnshareFailed(unshare_petbox::Error),
    #[error("failed to extract tar file: `{0}`")]
    CommandFailed(String),
    #[error("unknown data store error")]
    Unknown,
}
pub struct Rootfs {
    root_path: PathBuf,
}

impl Rootfs {
    pub fn new(root_path: &Path) -> Self {
        Self {
            root_path: root_path.into(),
        }
    }
    fn prepare_unshare_cmd(bin_name: &str) -> Command {
        let mut cmd = unshare_petbox::Command::new(bin_name);
        let mut namespaces = Vec::<Namespace>::new();
        namespaces.push(Namespace::User);
        let uid_map = gen_uidmap();
        trace!("uidmap:");
        trace!("{:#?}", uid_map);
        let gid_map = gen_gidmap();
        cmd.set_id_maps(uid_map, gid_map)
            .set_id_map_commands("/usr/bin/newuidmap", "/usr/bin/newgidmap");
        cmd.unshare(&namespaces);

        cmd.uid(0);
        cmd.gid(0);
        cmd
    }
    pub fn install_rootfs_enter_ns(&self,bin_name: &str) -> Result<(), RootfsError> {
        let mut cmd = Self::prepare_unshare_cmd(bin_name);
        match cmd.status() {
            Ok(r) => {
                if r.success() {
                    Ok(())
                } else {
                    Err(RootfsError::CommandFailed("F".to_string()))
                }
            }
            Err(e) => Err(RootfsError::UnshareFailed(e)),
        }
    }
    pub fn install_rootfs_from_tar(
        &self,
        tar_file: &Path,
    ) -> Result<(), RootfsError> {
        let mut cmd = Self::prepare_unshare_cmd("/bin/tar");
        DirBuilder::new().recursive(true).create(&self.root_path).unwrap();
        cmd.arg("xf")
            .arg(tar_file.as_os_str())
            .arg("--directory")
            .arg(&self.root_path.as_os_str());
        match cmd.status() {
            Ok(r) => {
                if r.success() {
                    Ok(())
                } else {
                    Err(RootfsError::CommandFailed("F".to_string()))
                }
            }
            Err(e) => Err(RootfsError::UnshareFailed(e)),
        }
    }
}