2021-08-02 02:34:31 +02:00
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use anyhow::{bail, Context, Result};
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2021-08-11 05:43:36 +02:00
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use nix::mount::mount as nix_mount;
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use nix::mount::MsFlags;
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2021-08-04 02:55:23 +02:00
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use crossbeam_channel::RecvTimeoutError;
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2021-08-02 02:34:31 +02:00
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use nix::{
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2021-08-04 02:55:23 +02:00
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fcntl, sched,
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2021-08-05 09:42:23 +02:00
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sys::statfs,
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unistd::{Gid, Uid},
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2021-08-02 02:34:31 +02:00
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};
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use oci_spec::Spec;
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2021-08-12 23:59:27 +02:00
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use std::collections::HashMap;
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2021-08-09 08:05:31 +02:00
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use std::{
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env,
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os::unix::{io::AsRawFd, prelude::RawFd},
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};
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2021-08-02 02:34:31 +02:00
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use std::{fs, io::Write, path::Path, path::PathBuf};
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2021-08-04 02:55:23 +02:00
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use std::{
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collections::HashMap,
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process, thread, time,
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2021-08-05 05:35:43 +02:00
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fmt,
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2021-08-04 02:55:23 +02:00
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};
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2021-08-02 02:34:31 +02:00
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use crate::{
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capabilities,
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2021-08-05 08:02:56 +02:00
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container::Container,
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2021-08-05 09:42:23 +02:00
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hook,
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2021-08-02 02:34:31 +02:00
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namespaces::Namespaces,
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notify_socket::NotifyListener,
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process::child,
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rootfs,
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syscall::{linux::LinuxSyscall, Syscall},
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tty, utils,
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};
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// Make sure a given path is on procfs. This is to avoid the security risk that
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// /proc path is mounted over. Ref: CVE-2019-16884
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fn ensure_procfs(path: &Path) -> Result<()> {
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let procfs_fd = fs::File::open(path)?;
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2021-08-04 02:55:23 +02:00
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let fstat_info = statfs::fstatfs(&procfs_fd.as_raw_fd())?;
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2021-08-02 02:34:31 +02:00
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2021-08-04 02:55:23 +02:00
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if fstat_info.filesystem_type() != statfs::PROC_SUPER_MAGIC {
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2021-08-02 02:34:31 +02:00
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bail!(format!("{:?} is not on the procfs", path));
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}
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Ok(())
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}
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// Get a list of open fds for the calling process.
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fn get_open_fds() -> Result<Vec<i32>> {
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const PROCFS_FD_PATH: &str = "/proc/self/fd";
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ensure_procfs(Path::new(PROCFS_FD_PATH))
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.with_context(|| format!("{} is not the actual procfs", PROCFS_FD_PATH))?;
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let fds: Vec<i32> = fs::read_dir(PROCFS_FD_PATH)?
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.filter_map(|entry| match entry {
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Ok(entry) => Some(entry.path()),
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Err(_) => None,
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})
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2021-08-04 09:05:34 +02:00
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.filter_map(|path| path.file_name().map(|file_name| file_name.to_owned()))
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.filter_map(|file_name| file_name.to_str().map(String::from))
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2021-08-02 02:34:31 +02:00
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.filter_map(|file_name| -> Option<i32> {
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// Convert the file name from string into i32. Since we are looking
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// at /proc/<pid>/fd, anything that's not a number (i32) can be
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// ignored. We are only interested in opened fds.
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match file_name.parse() {
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Ok(fd) => Some(fd),
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Err(_) => None,
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}
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})
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.collect();
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Ok(fds)
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}
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// Cleanup any extra file descriptors, so the new container process will not
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// leak a file descriptor from before execve gets executed. The first 3 fd will
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// stay open: stdio, stdout, and stderr. We would further preserve the next
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// "preserve_fds" number of fds. Set the rest of fd with CLOEXEC flag, so they
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// will be closed after execve into the container payload. We can't close the
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// fds immediatly since we at least still need it for the pipe used to wait on
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// starting the container.
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fn cleanup_file_descriptors(preserve_fds: i32) -> Result<()> {
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2021-08-02 08:24:08 +02:00
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let open_fds = get_open_fds().with_context(|| "Failed to obtain opened fds")?;
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2021-08-02 02:34:31 +02:00
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// Include stdin, stdout, and stderr for fd 0, 1, and 2 respectively.
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let min_fd = preserve_fds + 3;
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let to_be_cleaned_up_fds: Vec<i32> = open_fds
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.iter()
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2021-08-02 04:41:00 +02:00
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.filter_map(|&fd| if fd >= min_fd { Some(fd) } else { None })
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2021-08-02 02:34:31 +02:00
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.collect();
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2021-08-02 04:41:00 +02:00
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to_be_cleaned_up_fds.iter().for_each(|&fd| {
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2021-08-02 02:34:31 +02:00
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// Intentionally ignore errors here -- the cases where this might fail
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// are basically file descriptors that have already been closed.
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2021-08-02 04:41:00 +02:00
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let _ = fcntl::fcntl(fd, fcntl::F_SETFD(fcntl::FdFlag::FD_CLOEXEC));
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2021-08-02 02:34:31 +02:00
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});
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Ok(())
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}
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pub struct ContainerInitArgs {
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/// Flag indicating if an init or a tenant container should be created
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pub init: bool,
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/// Interface to operating system primitives
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pub syscall: LinuxSyscall,
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/// OCI complient runtime spec
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pub spec: Spec,
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/// Root filesystem of the container
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pub rootfs: PathBuf,
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/// Socket to communicate the file descriptor of the ptty
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2021-08-09 08:05:31 +02:00
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pub console_socket: Option<RawFd>,
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2021-08-02 02:34:31 +02:00
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/// Options for rootless containers
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2021-08-08 09:17:57 +02:00
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pub is_rootless: bool,
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2021-08-02 02:34:31 +02:00
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/// Path to the Unix Domain Socket to communicate container start
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pub notify_path: PathBuf,
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/// File descriptos preserved/passed to the container init process.
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pub preserve_fds: i32,
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2021-08-05 08:02:56 +02:00
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/// Container state
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pub container: Option<Container>,
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2021-08-02 02:34:31 +02:00
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/// Pipe used to communicate with the child process
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pub child: child::ChildProcess,
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}
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pub fn container_init(args: ContainerInitArgs) -> Result<()> {
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let command = &args.syscall;
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let spec = &args.spec;
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2021-08-09 07:54:24 +02:00
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let linux = spec.linux.as_ref().context("no linux in spec")?;
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2021-08-02 02:34:31 +02:00
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// need to create the notify socket before we pivot root, since the unix
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// domain socket used here is outside of the rootfs of container
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let mut notify_socket: NotifyListener = NotifyListener::new(&args.notify_path)?;
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2021-08-09 07:54:24 +02:00
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let proc = spec.process.as_ref().context("no process in spec")?;
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2021-08-09 12:34:14 +02:00
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let mut envs: Vec<String> = proc.env.as_ref().unwrap_or(&vec![]).clone();
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2021-08-02 02:34:31 +02:00
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let rootfs = &args.rootfs;
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2021-08-05 09:52:41 +02:00
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let mut envs: Vec<String> = proc.env.clone();
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2021-08-04 02:55:23 +02:00
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let hooks = spec.hooks.clone();
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2021-08-05 09:52:41 +02:00
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let mut child = args.child;
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2021-08-02 02:34:31 +02:00
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// if Out-of-memory score adjustment is set in specification. set the score
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// value for the current process check
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// https://dev.to/rrampage/surviving-the-linux-oom-killer-2ki9 for some more
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// information
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if let Some(ref resource) = linux.resources {
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if let Some(oom_score_adj) = resource.oom_score_adj {
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let mut f = fs::File::create("/proc/self/oom_score_adj")?;
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f.write_all(oom_score_adj.to_string().as_bytes())?;
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}
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}
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// if new user is specified in specification, this will be true and new
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// namespace will be created, check
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// https://man7.org/linux/man-pages/man7/user_namespaces.7.html for more
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// information
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2021-08-08 09:17:57 +02:00
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if args.is_rootless {
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2021-08-02 02:34:31 +02:00
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// child needs to be dumpable, otherwise the non root parent is not
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// allowed to write the uid/gid maps
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prctl::set_dumpable(true).unwrap();
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child.request_identifier_mapping()?;
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child.wait_for_mapping_ack()?;
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prctl::set_dumpable(false).unwrap();
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}
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// set limits and namespaces to the process
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2021-08-09 12:34:14 +02:00
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if let Some(rlimits) = proc.rlimits.as_ref() {
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for rlimit in rlimits.iter() {
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command.set_rlimit(rlimit).context("failed to set rlimit")?;
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}
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2021-08-02 02:34:31 +02:00
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}
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command
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.set_id(Uid::from_raw(0), Gid::from_raw(0))
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.context("failed to become root")?;
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// set up tty if specified
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if let Some(csocketfd) = args.console_socket {
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tty::setup_console(&csocketfd)?;
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}
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// join existing namespaces
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2021-08-11 15:34:33 +02:00
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let bind_service = if let Some(ns) = linux.namespaces.as_ref() {
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let namespaces = Namespaces::from(ns);
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namespaces.apply_setns()?;
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namespaces
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.clone_flags
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.contains(sched::CloneFlags::CLONE_NEWUSER)
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} else {
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false
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};
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2021-08-02 02:34:31 +02:00
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2021-08-09 12:34:14 +02:00
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if let Some(hostname) = spec.hostname.as_ref() {
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command.set_hostname(hostname)?;
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}
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2021-08-02 02:34:31 +02:00
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2021-08-04 13:41:00 +02:00
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if let Some(true) = proc.no_new_privileges {
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2021-08-02 02:34:31 +02:00
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let _ = prctl::set_no_new_privileges(true);
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}
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if args.init {
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2021-08-05 09:42:23 +02:00
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// create_container hook needs to be called after the namespace setup, but
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// before pivot_root is called. This runs in the container namespaces.
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2021-08-04 02:55:23 +02:00
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if let Some(hooks) = hooks {
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2021-08-05 09:42:23 +02:00
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hook::run_hooks(hooks.create_container, args.container)?
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2021-08-04 02:55:23 +02:00
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}
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2021-08-11 15:34:33 +02:00
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rootfs::prepare_rootfs(spec, rootfs, bind_service)
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.with_context(|| "Failed to prepare rootfs")?;
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2021-08-02 02:34:31 +02:00
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// change the root of filesystem of the process to the rootfs
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command
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.pivot_rootfs(rootfs)
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.with_context(|| format!("Failed to pivot root to {:?}", rootfs))?;
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2021-08-12 23:59:27 +02:00
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if let Some(kernel_params) = &linux.sysctl {
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sysctl(kernel_params)?;
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}
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2021-08-02 02:34:31 +02:00
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}
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|
2021-08-11 05:43:36 +02:00
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if let Some(paths) = &linux.readonly_paths {
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// mount readonly path
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for path in paths {
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readonly_path(path)?;
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}
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}
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2021-08-02 02:34:31 +02:00
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command.set_id(Uid::from_raw(proc.user.uid), Gid::from_raw(proc.user.gid))?;
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capabilities::reset_effective(command)?;
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|
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if let Some(caps) = &proc.capabilities {
|
2021-08-04 09:05:34 +02:00
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capabilities::drop_privileges(caps, command)?;
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2021-08-02 02:34:31 +02:00
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}
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|
2021-08-02 20:37:54 +02:00
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// Take care of LISTEN_FDS used for systemd-active-socket. If the value is
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// not 0, then we have to preserve those fds as well, and set up the correct
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// environment variables.
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let preserve_fds: i32 = match env::var("LISTEN_FDS") {
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Ok(listen_fds_str) => {
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2021-08-02 20:42:23 +02:00
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let listen_fds = match listen_fds_str.parse::<i32>() {
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2021-08-02 20:37:54 +02:00
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Ok(v) => v,
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Err(error) => {
|
2021-08-02 20:42:23 +02:00
|
|
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log::warn!(
|
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|
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"LISTEN_FDS entered is not a fd. Ignore the value. {:?}",
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|
|
|
error
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);
|
2021-08-02 20:37:54 +02:00
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0
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}
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};
|
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|
2021-08-02 20:48:58 +02:00
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|
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// The LISTEN_FDS will have to be passed to container init process.
|
|
|
|
// The LISTEN_PID will be set to PID 1. Based on the spec, if
|
|
|
|
// LISTEN_FDS is 0, the variable should be unset, so we just ignore
|
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|
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// it here, if it is 0.
|
|
|
|
if listen_fds > 0 {
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|
envs.append(&mut vec![
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|
|
format!("LISTEN_FDS={}", listen_fds),
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|
|
"LISTEN_PID=1".to_string(),
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|
]);
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|
|
|
}
|
|
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|
|
2021-08-02 20:37:54 +02:00
|
|
|
args.preserve_fds + listen_fds
|
2021-08-02 20:42:23 +02:00
|
|
|
}
|
|
|
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Err(env::VarError::NotPresent) => args.preserve_fds,
|
2021-08-02 20:37:54 +02:00
|
|
|
Err(env::VarError::NotUnicode(value)) => {
|
2021-08-02 20:42:23 +02:00
|
|
|
log::warn!(
|
|
|
|
"LISTEN_FDS entered is malformed: {:?}. Ignore the value.",
|
|
|
|
&value
|
|
|
|
);
|
2021-08-02 20:37:54 +02:00
|
|
|
args.preserve_fds
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|
|
|
}
|
|
|
|
};
|
|
|
|
|
2021-08-02 02:34:31 +02:00
|
|
|
// clean up and handle perserved fds.
|
2021-08-02 20:37:54 +02:00
|
|
|
cleanup_file_descriptors(preserve_fds).with_context(|| "Failed to clean up extra fds")?;
|
2021-08-02 02:34:31 +02:00
|
|
|
|
2021-08-05 09:52:41 +02:00
|
|
|
// Reset the process env based on oci spec.
|
|
|
|
env::vars().for_each(|(key, _value)| std::env::remove_var(key));
|
|
|
|
utils::parse_env(envs).iter().for_each(|(key, value)| {
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|
|
env::set_var(key, value)
|
|
|
|
});
|
|
|
|
|
2021-08-02 02:34:31 +02:00
|
|
|
// notify parents that the init process is ready to execute the payload.
|
|
|
|
child.notify_parent()?;
|
|
|
|
|
|
|
|
// listing on the notify socket for container start command
|
|
|
|
notify_socket.wait_for_container_start()?;
|
|
|
|
|
2021-08-05 09:42:23 +02:00
|
|
|
// create_container hook needs to be called after the namespace setup, but
|
|
|
|
// before pivot_root is called. This runs in the container namespaces.
|
|
|
|
// if let Some(hooks) = hooks {
|
|
|
|
// hook::run_hooks(hooks.start_container, args.container)?
|
|
|
|
// }
|
2021-08-09 12:34:14 +02:00
|
|
|
if let Some(args) = proc.args.as_ref() {
|
|
|
|
utils::do_exec(&args[0], args, &envs)?;
|
|
|
|
} else {
|
|
|
|
log::warn!("The command to be executed isn't set")
|
|
|
|
}
|
2021-08-02 02:34:31 +02:00
|
|
|
|
|
|
|
// After do_exec is called, the process is replaced with the container
|
|
|
|
// payload through execvp, so it should never reach here.
|
|
|
|
unreachable!();
|
|
|
|
}
|
2021-08-02 04:41:17 +02:00
|
|
|
|
2021-08-12 23:59:27 +02:00
|
|
|
fn sysctl(kernel_params: &HashMap<String, String>) -> Result<()> {
|
|
|
|
let sys = PathBuf::from("/proc/sys");
|
|
|
|
for (kernel_param, value) in kernel_params {
|
|
|
|
let path = sys.join(kernel_param.replace(".", "/"));
|
|
|
|
log::debug!(
|
|
|
|
"apply value {} to kernel parameter {}.",
|
|
|
|
value,
|
|
|
|
kernel_param
|
|
|
|
);
|
|
|
|
fs::write(path, value.as_bytes())
|
|
|
|
.with_context(|| format!("failed to set sysctl {}={}", kernel_param, value))?;
|
|
|
|
}
|
|
|
|
|
|
|
|
Ok(())
|
|
|
|
}
|
|
|
|
|
2021-08-11 05:43:36 +02:00
|
|
|
fn readonly_path(path: &str) -> Result<()> {
|
|
|
|
match nix_mount::<str, str, str, str>(
|
|
|
|
Some(path),
|
|
|
|
path,
|
|
|
|
None::<&str>,
|
|
|
|
MsFlags::MS_BIND
|
|
|
|
| MsFlags::MS_REC
|
|
|
|
| MsFlags::MS_NOSUID
|
|
|
|
| MsFlags::MS_NODEV
|
|
|
|
| MsFlags::MS_NOEXEC
|
|
|
|
| MsFlags::MS_BIND
|
|
|
|
| MsFlags::MS_RDONLY,
|
|
|
|
None::<&str>,
|
|
|
|
) {
|
|
|
|
// ignore error if path is not exist.
|
|
|
|
Err(nix::errno::Errno::ENOENT) => {
|
|
|
|
log::warn!("readonly path {:?} not exist", path);
|
|
|
|
return Ok(());
|
|
|
|
}
|
|
|
|
Err(err) => bail!(err),
|
|
|
|
Ok(_) => {}
|
|
|
|
}
|
|
|
|
log::debug!("readonly path {:?} mounted", path);
|
|
|
|
Ok(())
|
|
|
|
}
|
|
|
|
|
2021-08-02 04:41:17 +02:00
|
|
|
#[cfg(test)]
|
|
|
|
mod tests {
|
|
|
|
use super::*;
|
|
|
|
use anyhow::{bail, Result};
|
|
|
|
use nix::{fcntl, sys, unistd};
|
|
|
|
use std::fs;
|
|
|
|
|
|
|
|
#[test]
|
|
|
|
fn test_get_open_fds() -> Result<()> {
|
|
|
|
let file = fs::File::open("/dev/null")?;
|
|
|
|
let fd = file.as_raw_fd();
|
|
|
|
let open_fds = super::get_open_fds()?;
|
|
|
|
|
|
|
|
if !open_fds.iter().any(|&v| v == fd) {
|
|
|
|
bail!("Failed to find the opened dev null fds: {:?}", open_fds);
|
|
|
|
}
|
|
|
|
|
|
|
|
// explicitly close the file before the test case returns.
|
|
|
|
drop(file);
|
|
|
|
|
|
|
|
// The stdio fds should also be contained in the list of opened fds.
|
|
|
|
if !vec![0, 1, 2]
|
|
|
|
.iter()
|
|
|
|
.all(|&stdio_fd| open_fds.iter().any(|&open_fd| open_fd == stdio_fd))
|
|
|
|
{
|
|
|
|
bail!("Failed to find the stdio fds: {:?}", open_fds);
|
|
|
|
}
|
|
|
|
|
|
|
|
Ok(())
|
|
|
|
}
|
|
|
|
|
|
|
|
#[test]
|
|
|
|
fn test_cleanup_file_descriptors() -> Result<()> {
|
|
|
|
// Open a fd without the CLOEXEC flag. Rust automatically adds the flag,
|
|
|
|
// so we use fcntl::open here for more control.
|
|
|
|
let fd = fcntl::open("/dev/null", fcntl::OFlag::O_RDWR, sys::stat::Mode::empty())?;
|
|
|
|
cleanup_file_descriptors(fd - 1).with_context(|| "Failed to clean up the fds")?;
|
|
|
|
let fd_flag = fcntl::fcntl(fd, fcntl::F_GETFD)?;
|
|
|
|
if (fd_flag & fcntl::FdFlag::FD_CLOEXEC.bits()) != 0 {
|
|
|
|
bail!("CLOEXEC flag is not set correctly");
|
|
|
|
}
|
|
|
|
|
|
|
|
unistd::close(fd)?;
|
|
|
|
Ok(())
|
|
|
|
}
|
|
|
|
}
|