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rootmap.rs
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rootmap.rs
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// Copyright 2020 CoreOS, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
use anyhow::{bail, Context, Result};
use nix::mount;
use std::collections::HashMap;
use std::path::{Path, PathBuf};
use std::process::Command;
use libcoreinst::blockdev::*;
use libcoreinst::install::*;
use libcoreinst::util::*;
use libcoreinst::runcmd_output;
use crate::cmdline::*;
pub fn rootmap(config: &RootMapConfig) -> Result<()> {
// get the backing device for the root mount
let mount = Mount::from_existing(&config.root_mount)?;
let device = PathBuf::from(mount.device());
// and from that we can collect all the parent backing devices too
let mut backing_devices = get_blkdev_deps_recursing(&device)?;
backing_devices.push(device);
// for each of those, convert them to kargs
let mut kargs = Vec::new();
for backing_device in backing_devices {
if let Some(dev_kargs) = device_to_kargs(&mount, backing_device)? {
kargs.extend(dev_kargs);
}
}
// we push the root kargs last, this has the nice property that the final order of kargs goes
// from lowest level to highest; see also
// https://github.com/coreos/fedora-coreos-tracker/issues/465
kargs.push(format!("root=UUID={}", mount.get_filesystem_uuid()?));
// we need this because with root= it's systemd that takes care of mounting via
// systemd-fstab-generator, and it defaults to read-only otherwise
kargs.push("rw".into());
let rootflags = runcmd_output!("coreos-rootflags", &config.root_mount)?;
let rootflags = rootflags.trim();
if !rootflags.is_empty() {
kargs.push(format!("rootflags={}", rootflags));
}
let boot_mount = get_boot_mount_from_cmdline_args(&config.boot_mount, &config.boot_device)?;
if let Some(mount) = boot_mount {
visit_bls_entry_options(mount.mountpoint(), |orig_options: &str| {
bls_entry_options_delete_and_append_kargs(orig_options, &[], &kargs, &[])
})
.context("appending rootmap kargs")?;
eprintln!("Injected kernel arguments into BLS: {}", kargs.join(" "));
} else {
// without /boot options, we just print the kargs; note we output to stdout here
println!("{}", kargs.join(" "));
}
Ok(())
}
// This is shared with the kargs code -- might move this to a helper file eventually
pub fn get_boot_mount_from_cmdline_args(
boot_mount: &Option<String>,
boot_device: &Option<String>,
) -> Result<Option<Mount>> {
if let Some(path) = boot_mount {
Ok(Some(Mount::from_existing(path)?))
} else if let Some(devpath) = boot_device {
let devinfo = lsblk_single(Path::new(devpath))?;
let fs = devinfo
.get("FSTYPE")
.with_context(|| format!("failed to query filesystem for {}", devpath))?;
Ok(Some(Mount::try_mount(
devpath,
fs,
mount::MsFlags::empty(),
)?))
} else {
Ok(None)
}
}
fn device_to_kargs(root: &Mount, device: PathBuf) -> Result<Option<Vec<String>>> {
let blkinfo = lsblk_single(&device)?;
let blktype = blkinfo
.get("TYPE")
.with_context(|| format!("missing TYPE for {}", device.display()))?;
// a `match {}` construct would be nice here, but for RAID it's a prefix match
if blktype.starts_with("raid") {
Ok(Some(get_raid_kargs(&device)?))
} else if blktype == "crypt" {
Ok(Some(get_luks_kargs(root, &device)?))
} else if blktype == "part" || blktype == "disk" || blktype == "mpath" {
Ok(None)
} else {
bail!("unknown block device type {}", blktype)
}
}
fn get_raid_kargs(device: &Path) -> Result<Vec<String>> {
let details = mdadm_detail(device)?;
let uuid = details
.get("MD_UUID")
.with_context(|| format!("missing MD_UUID for {}", device.display()))?;
Ok(vec![format!("rd.md.uuid={}", uuid)])
}
fn mdadm_detail(device: &Path) -> Result<HashMap<String, String>> {
let output = runcmd_output!("mdadm", "--detail", "--export", device)?;
let mut result: HashMap<String, String> = HashMap::new();
for line in output.lines() {
let (key, val) = split_mdadm_line(line)?;
result.insert(key, val);
}
Ok(result)
}
fn split_mdadm_line(line: &str) -> Result<(String, String)> {
let v: Vec<&str> = line.splitn(2, '=').collect();
if v.len() != 2 {
bail!("invalid mdadm line: {}", line);
}
Ok((v[0].into(), v[1].into()))
}
fn get_luks_kargs(root: &Mount, device: &Path) -> Result<Vec<String>> {
// The LUKS UUID is a property of the backing block device of *this* block device, so we have
// to get its parent. This is a bit awkward because we're already iterating through parents, so
// theoretically we could re-use the same state here. But meh... this is easier to understand.
let deps = get_blkdev_deps(device)?;
match deps.len() {
0 => bail!("missing parent device for {}", device.display()),
1 => {
let uuid = get_luks_uuid(&deps[0])?;
let name = get_luks_name(device)?;
let mut kargs = vec![format!("rd.luks.name={}={}", uuid, name)];
if crypttab_device_has_netdev(root, &name)? {
kargs.push("rd.neednet=1".into());
kargs.push("rd.luks.options=_netdev".into());
}
Ok(kargs)
}
_ => bail!(
"found multiple parent devices for crypt device {}",
device.display()
),
}
}
// crypttab is the source of truth for whether an encrypted block device requires networking.
fn crypttab_device_has_netdev(root: &Mount, dmname: &str) -> Result<bool> {
let crypttab_path = root.mountpoint().join("etc/crypttab");
let crypttab = std::fs::read_to_string(&crypttab_path)
.with_context(|| format!("opening {}", crypttab_path.display()))?;
for line in crypttab.lines() {
let line = line.trim();
if line.is_empty() || line.starts_with('#') {
continue;
}
let fields: Vec<&str> = line.split_whitespace().collect();
// from crypttab(5), format is:
// name encrypted-device password options
// first two fields are mandatory, remaining are optional
if fields.len() < 2 {
bail!("crypttab line missing name or device: {}", line);
}
if fields[0] != dmname {
continue;
}
if fields.len() < 4 {
return Ok(false);
}
return Ok(fields[3].split(',').any(|opt| opt == "_netdev"));
}
bail!("couldn't find {} in {}", dmname, crypttab_path.display());
}
fn get_luks_name(device: &Path) -> Result<String> {
Ok(runcmd_output!(
"dmsetup",
"info",
"--columns",
"--noheadings",
"-o",
"name",
device
)?
.trim()
.into())
}
fn get_luks_uuid(device: &Path) -> Result<String> {
Ok(runcmd_output!("cryptsetup", "luksUUID", device)?
.trim()
.into())
}