libcontainer: support set stdio for container

currently the container can only inherit stdios from it's parent
process, the one who create container with libcontainer can not set
stdios to a different file.

Signed-off-by: Abel Feng <[email protected]>

crates/libcontainer/src/container/builder.rs

@@ -1,3 +1,4 @@
+use std::os::fd::OwnedFd;
 use std::path::PathBuf;
 
 use super::init_builder::InitContainerBuilder;
@@ -24,6 +25,12 @@ pub struct ContainerBuilder {
     /// The function that actually runs on the container init process. Default
     /// is to execute the specified command in the oci spec.
     pub(super) executor: Box<dyn Executor>,
+    // RawFd set to stdin of the container init process.
+    pub stdin: Option<OwnedFd>,
+    // RawFd set to stdout of the container init process.
+    pub stdout: Option<OwnedFd>,
+    // RawFd set to stderr of the container init process.
+    pub stderr: Option<OwnedFd>,
 }
 
 /// Builder that can be used to configure the common properties of
@@ -70,6 +77,9 @@ impl ContainerBuilder {
             console_socket: None,
             preserve_fds: 0,
             executor: workload::default::get_executor(),
+            stdin: None,
+            stdout: None,
+            stderr: None,
         }
     }
 
@@ -257,13 +267,84 @@ impl ContainerBuilder {
         self.executor = Box::new(executor);
         self
     }
+
+    /// Sets the stdin of the container, for those who use libcontainer as an library,
+    /// the container stdin may not have to be set to an opened file descriptor
+    /// rather than the stdin of the current process.
+    /// # Example
+    ///
+    /// ```no_run
+    /// # use libcontainer::container::builder::ContainerBuilder;
+    /// # use libcontainer::syscall::syscall::SyscallType;
+    /// # use libcontainer::workload::default::DefaultExecutor;
+    /// # use nix::unistd::pipe;
+    ///
+    /// let (r, _w) = pipe().unwrap();
+    /// ContainerBuilder::new(
+    ///     "74f1a4cb3801".to_owned(),
+    ///     SyscallType::default(),
+    /// )
+    /// .with_stdin(r);
+    /// ```
+    pub fn with_stdin(mut self, stdin: OwnedFd) -> Self {
+        self.stdin = Some(stdin);
+        self
+    }
+
+    /// Sets the stdout of the container, for those who use libcontainer as an library,
+    /// the container stdout may not have to be set to an opened file descriptor
+    /// rather than the stdout of the current process.
+    /// # Example
+    ///
+    /// ```no_run
+    /// # use libcontainer::container::builder::ContainerBuilder;
+    /// # use libcontainer::syscall::syscall::SyscallType;
+    /// # use libcontainer::workload::default::DefaultExecutor;
+    /// # use nix::unistd::pipe;
+    ///
+    /// let (_r, w) = pipe().unwrap();
+    /// ContainerBuilder::new(
+    ///     "74f1a4cb3801".to_owned(),
+    ///     SyscallType::default(),
+    /// )
+    /// .with_stdout(w);
+    /// ```
+    pub fn with_stdout(mut self, stdout: OwnedFd) -> Self {
+        self.stdout = Some(stdout);
+        self
+    }
+
+    /// Sets the stderr of the container, for those who use libcontainer as an library,
+    /// the container stderr may not have to be set to an opened file descriptor
+    /// rather than the stderr of the current process.
+    /// # Example
+    ///
+    /// ```no_run
+    /// # use libcontainer::container::builder::ContainerBuilder;
+    /// # use libcontainer::syscall::syscall::SyscallType;
+    /// # use libcontainer::workload::default::DefaultExecutor;
+    /// # use nix::unistd::pipe;
+    ///
+    /// let (_r, w) = pipe().unwrap();
+    /// ContainerBuilder::new(
+    ///     "74f1a4cb3801".to_owned(),
+    ///     SyscallType::default(),
+    /// )
+    /// .with_stderr(w);
+    /// ```
+    pub fn with_stderr(mut self, stderr: OwnedFd) -> Self {
+        self.stderr = Some(stderr);
+        self
+    }
 }
 
 #[cfg(test)]
 mod tests {
+    use std::os::fd::AsRawFd;
     use std::path::PathBuf;
 
     use anyhow::{Context, Result};
+    use nix::unistd::pipe;
 
     use crate::container::builder::ContainerBuilder;
     use crate::syscall::syscall::SyscallType;
@@ -334,4 +415,35 @@ mod tests {
         assert!(result.is_ok());
         Ok(())
     }
+
+    #[test]
+    fn test_stdios() -> Result<()> {
+        let (r, _w) = pipe()?;
+        let stdin_raw = r.as_raw_fd();
+        let builder =
+            ContainerBuilder::new("74f1a4cb3801".to_owned(), SyscallType::default()).with_stdin(r);
+        assert_eq!(
+            builder.stdin.as_ref().map(|o| o.as_raw_fd()),
+            Some(stdin_raw)
+        );
+
+        let (_r, w) = pipe()?;
+        let stdout_raw = w.as_raw_fd();
+        let builder =
+            ContainerBuilder::new("74f1a4cb3801".to_owned(), SyscallType::default()).with_stdout(w);
+        assert_eq!(
+            builder.stdout.as_ref().map(|o| o.as_raw_fd()),
+            Some(stdout_raw)
+        );
+
+        let (_r, w) = pipe()?;
+        let stderr_raw = w.as_raw_fd();
+        let builder =
+            ContainerBuilder::new("74f1a4cb3801".to_owned(), SyscallType::default()).with_stderr(w);
+        assert_eq!(
+            builder.stderr.as_ref().map(|o| o.as_raw_fd()),
+            Some(stderr_raw)
+        );
+        Ok(())
+    }
 }

crates/libcontainer/src/container/builder_impl.rs

@@ -1,5 +1,6 @@
 use std::fs;
 use std::io::Write;
+use std::os::fd::{AsRawFd, OwnedFd};
 use std::os::unix::prelude::RawFd;
 use std::path::PathBuf;
 use std::rc::Rc;
@@ -51,6 +52,12 @@ pub(super) struct ContainerBuilderImpl {
     pub executor: Box<dyn Executor>,
     /// If do not use pivot root to jail process inside rootfs
     pub no_pivot: bool,
+    // RawFd set to stdin of the container init process.
+    pub stdin: Option<OwnedFd>,
+    // RawFd set to stdout of the container init process.
+    pub stdout: Option<OwnedFd>,
+    // RawFd set to stderr of the container init process.
+    pub stderr: Option<OwnedFd>,
 }
 
 impl ContainerBuilderImpl {
@@ -157,6 +164,9 @@ impl ContainerBuilderImpl {
             detached: self.detached,
             executor: self.executor.clone(),
             no_pivot: self.no_pivot,
+            stdin: self.stdin.as_ref().map(|x| x.as_raw_fd()),
+            stdout: self.stdout.as_ref().map(|x| x.as_raw_fd()),
+            stderr: self.stderr.as_ref().map(|x| x.as_raw_fd()),
         };
 
         let (init_pid, need_to_clean_up_intel_rdt_dir) =

crates/libcontainer/src/container/init_builder.rs

@@ -103,6 +103,9 @@ impl InitContainerBuilder {
             detached: self.detached,
             executor: self.base.executor,
             no_pivot: self.no_pivot,
+            stdin: self.base.stdin,
+            stdout: self.base.stdout,
+            stderr: self.base.stderr,
         };
 
         builder_impl.create()?;

crates/libcontainer/src/container/tenant_builder.rs

@@ -143,6 +143,9 @@ impl TenantContainerBuilder {
             detached: self.detached,
             executor: self.base.executor,
             no_pivot: false,
+            stdin: self.base.stdin,
+            stdout: self.base.stdout,
+            stderr: self.base.stderr,
         };
 
         let pid = builder_impl.create()?;

crates/libcontainer/src/process/args.rs

@@ -44,4 +44,10 @@ pub struct ContainerArgs {
     pub executor: Box<dyn Executor>,
     /// If do not use pivot root to jail process inside rootfs
     pub no_pivot: bool,
+    // RawFd set to stdin of the container init process.
+    pub stdin: Option<RawFd>,
+    // RawFd set to stdout of the container init process.
+    pub stdout: Option<RawFd>,
+    // RawFd set to stderr of the container init process.
+    pub stderr: Option<RawFd>,
 }

crates/libcontainer/src/process/container_init_process.rs

@@ -7,7 +7,7 @@ use nc;
 use nix::mount::{MntFlags, MsFlags};
 use nix::sched::CloneFlags;
 use nix::sys::stat::Mode;
-use nix::unistd::{self, setsid, Gid, Uid};
+use nix::unistd::{self, close, dup2, setsid, Gid, Uid};
 use oci_spec::runtime::{
     IOPriorityClass, LinuxIOPriority, LinuxNamespaceType, LinuxSchedulerFlag, LinuxSchedulerPolicy,
     Scheduler, Spec, User,
@@ -374,6 +374,19 @@ pub fn container_init_process(
             tracing::error!(?err, "failed to set up tty");
             InitProcessError::Tty(err)
         })?;
+    } else {
+        if let Some(stdin) = args.stdin {
+            dup2(stdin, 0).map_err(InitProcessError::NixOther)?;
+            close(stdin).map_err(InitProcessError::NixOther)?;
+        }
+        if let Some(stdout) = args.stdout {
+            dup2(stdout, 1).map_err(InitProcessError::NixOther)?;
+            close(stdout).map_err(InitProcessError::NixOther)?;
+        }
+        if let Some(stderr) = args.stderr {
+            dup2(stderr, 2).map_err(InitProcessError::NixOther)?;
+            close(stderr).map_err(InitProcessError::NixOther)?;
+        }
     }
 
     apply_rest_namespaces(&namespaces, spec, syscall.as_ref())?;