From 787c2e03d7e9a4f8fa4e91f7e3eb19a8ca98371e Mon Sep 17 00:00:00 2001 From: Dominik Csapak Date: Fri, 29 Nov 2024 15:28:01 +0100 Subject: [PATCH] sys: open directories with O_CLOEXEC MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Factor out the open-flags to use for directories and add the CLOEXEC flag to ensure that open FDs do not get passed to any child process. A prominent cases where this can happen is the proxmox-daemon reload code, which re-execs itself in a forked child-process and thus gets all FDs passed. Signed-off-by: Dominik Csapak Reviewed-by: Fabian Grünbichler [ TL: expand doc-comment and reword commit message to point at actual thing this fixes (exec not daemon reload) ] Signed-off-by: Thomas Lamprecht --- proxmox-sys/src/fd.rs | 2 +- proxmox-sys/src/fs/dir.rs | 17 +++++++++++------ 2 files changed, 12 insertions(+), 7 deletions(-) diff --git a/proxmox-sys/src/fd.rs b/proxmox-sys/src/fd.rs index 8d85bd2e..386e4222 100644 --- a/proxmox-sys/src/fd.rs +++ b/proxmox-sys/src/fd.rs @@ -24,7 +24,7 @@ pub fn change_cloexec(fd: RawFd, on: bool) -> Result<(), anyhow::Error> { } pub(crate) fn cwd() -> Result { - open(".", OFlag::O_DIRECTORY, stat::Mode::empty()) + open(".", crate::fs::DIR_FLAGS, stat::Mode::empty()) } pub fn open

(path: &P, oflag: OFlag, mode: Mode) -> Result diff --git a/proxmox-sys/src/fs/dir.rs b/proxmox-sys/src/fs/dir.rs index c903ab87..e4f45bbd 100644 --- a/proxmox-sys/src/fs/dir.rs +++ b/proxmox-sys/src/fs/dir.rs @@ -14,6 +14,11 @@ use proxmox_lang::try_block; use crate::fs::{fchown, CreateOptions}; +/// The default list of [`OFlag`]'s we want to use when opening directories. Besides ensuring that +/// the FD indeed points to a directory we also must ensure that it gets closed on exec to avoid +/// leaking a open FD to a child process. +pub(crate) const DIR_FLAGS: OFlag = OFlag::O_DIRECTORY.union(OFlag::O_CLOEXEC); + /// Creates directory at the provided path with specified ownership. /// /// Errors if the directory already exists. @@ -66,7 +71,7 @@ pub fn ensure_dir_exists>( Err(err) => bail!("unable to create directory {path:?} - {err}",), } - let fd = nix::fcntl::open(path, OFlag::O_DIRECTORY, stat::Mode::empty()) + let fd = nix::fcntl::open(path, DIR_FLAGS, stat::Mode::empty()) .map(|fd| unsafe { OwnedFd::from_raw_fd(fd) }) .map_err(|err| format_err!("unable to open created directory {path:?} - {err}"))?; // umask defaults to 022 so make sure the mode is fully honowed: @@ -120,7 +125,7 @@ fn create_path_do( Some(Component::Prefix(_)) => bail!("illegal prefix path component encountered"), Some(Component::RootDir) => { let _ = iter.next(); - crate::fd::open(c"/", OFlag::O_DIRECTORY, stat::Mode::empty())? + crate::fd::open(c"/", DIR_FLAGS, stat::Mode::empty())? } Some(Component::CurDir) => { let _ = iter.next(); @@ -128,7 +133,7 @@ fn create_path_do( } Some(Component::ParentDir) => { let _ = iter.next(); - crate::fd::open(c"..", OFlag::O_DIRECTORY, stat::Mode::empty())? + crate::fd::open(c"..", DIR_FLAGS, stat::Mode::empty())? } Some(Component::Normal(_)) => { // simply do not advance the iterator, heavy lifting happens in create_path_at_do() @@ -154,7 +159,7 @@ fn create_path_at_do( None => return Ok(created), Some(Component::ParentDir) => { - at = crate::fd::openat(&at, c"..", OFlag::O_DIRECTORY, stat::Mode::empty())?; + at = crate::fd::openat(&at, c"..", DIR_FLAGS, stat::Mode::empty())?; } Some(Component::Normal(path)) => { @@ -175,7 +180,7 @@ fn create_path_at_do( Err(e) => return Err(e.into()), Ok(_) => true, }; - at = crate::fd::openat(&at, path, OFlag::O_DIRECTORY, stat::Mode::empty())?; + at = crate::fd::openat(&at, path, DIR_FLAGS, stat::Mode::empty())?; if let (true, Some(opts)) = (created, opts) { if opts.owner.is_some() || opts.group.is_some() { @@ -222,7 +227,7 @@ pub fn make_tmp_dir>( if let Some(options) = options { if let Err(err) = try_block!({ - let mut fd = crate::fd::open(&path, OFlag::O_DIRECTORY, stat::Mode::empty())?; + let mut fd = crate::fd::open(&path, DIR_FLAGS, stat::Mode::empty())?; options.apply_to(&mut fd, &path)?; Ok::<(), Error>(()) }) {