;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2015 David Thompson <davet@gnu.org>
;;; Copyright © 2017-2019, 2022, 2023 Ludovic Courtès <ludo@gnu.org>
;;;
;;; This file is part of GNU Guix.
;;;
;;; GNU Guix is free software; you can redistribute it and/or modify it
;;; under the terms of the GNU General Public License as published by
;;; the Free Software Foundation; either version 3 of the License, or (at
;;; your option) any later version.
;;;
;;; GNU Guix is distributed in the hope that it will be useful, but
;;; WITHOUT ANY WARRANTY; without even the implied warranty of
;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
;;; GNU General Public License for more details.
;;;
;;; You should have received a copy of the GNU General Public License
;;; along with GNU Guix. If not, see <http://www.gnu.org/licenses/>.
(define-module (gnu build linux-container)
#:use-module (ice-9 format)
#:use-module (ice-9 match)
#:use-module (ice-9 rdelim)
#:use-module (srfi srfi-98)
#:use-module (guix build utils)
#:use-module (guix build syscalls)
#:use-module (gnu system file-systems) ;<file-system>
#:use-module ((gnu build file-systems) #:select (mount-file-system))
#:export (user-namespace-supported?
unprivileged-user-namespace-supported?
setgroups-supported?
%namespaces
run-container
call-with-container
container-excursion
container-excursion*))
(define (user-namespace-supported?)
"Return #t if user namespaces are supported on this system."
(file-exists? "/proc/self/ns/user"))
(define (unprivileged-user-namespace-supported?)
"Return #t if user namespaces can be created by unprivileged users."
(let ((userns-file "/proc/sys/kernel/unprivileged_userns_clone"))
(if (file-exists? userns-file)
(eqv? #\1 (call-with-input-file userns-file read-char))
#t)))
(define (setgroups-supported?)
"Return #t if the setgroups proc file, introduced in Linux-libre 3.19,
exists."
(file-exists? "/proc/self/setgroups"))
(define %namespaces
'(cgroup mnt pid ipc uts user net))
(define (call-with-clean-exit thunk)
"Apply THUNK, but exit with a status code of 1 if it fails."
(dynamic-wind
(const #t)
(lambda ()
(thunk)
;; XXX: Somehow we sometimes get EBADF from write(2) or close(2) upon
;; exit (coming from fd finalizers) when used by the Shepherd. To work
;; around that, exit forcefully so fd finalizers don't have a chance to
;; run and fail.
(primitive-_exit 0))
(lambda ()
(primitive-_exit 1))))
(define (purify-environment)
"Unset all environment variables."
(for-each unsetenv
(match (get-environment-variables)
(((names . _) ...) names))))
;; The container setup procedure closely resembles that of the Docker
;; specification:
;; https://raw.githubusercontent.com/docker/libcontainer/master/SPEC.md
(define* (mount-file-systems root mounts #:key mount-/sys? mount-/proc?)
"Mount the essential file systems and the those in MOUNTS, a list of
<file-system> objects, relative to ROOT; then make ROOT the new root directory
for the process."
(define (scope dir)
(string-append root dir))
(define (touch file-name)
(call-with-| 2022-02-02 | installer: Make dump archive creation optional and selective....* gnu/installer.scm (installer-program): Let the installer customize
the dump archive.
* gnu/installer/dump.scm (prepare-dump, make-dump): Split make-dump in
prepare-dump, which copies the files necessary for the dump, and
make-dump which creates the archive.
* gnu/installer/record.scm (installer): Add report-page field. Change
documented return value of exit-error.
* gnu/installer/newt.scm (exit-error): Change arguments to be a string
containing the error. Let the user choose between exiting and
initiating a dump.
(report-page): Add new variable.
* gnu/installer/newt/page.scm (run-dump-page): New variable.
* gnu/installer/newt/dump.scm: Delete it.
Signed-off-by: Mathieu Othacehe <othacehe@gnu.org>
| Josselin Poiret |
| 2022-02-02 | installer: Add error page when running external commands....* gnu/installer/newt.scm (newt-run-command): Add it.
* gnu/installer/newt/page.scm (%ok-button, %exit-button,
%default-buttons, make-newt-buttons, run-textbox-page): Add them.
Signed-off-by: Mathieu Othacehe <othacehe@gnu.org>
| Josselin Poiret |
| 2022-02-02 | installer: Add installer-specific run command process....* gnu/installer/record.scm (installer)[run-command]: Add field.
* gnu/installer/utils.scm (run-command-in-installer): Add parameter.
* gnu/installer.scm (installer-program): Parameterize
run-command-in-installer with current installer's run-command.
* gnu/installer/newt.scm (newt-run-command): New variable.
(newt-installer): Use it.
Signed-off-by: Mathieu Othacehe <othacehe@gnu.org>
| Josselin Poiret |
| 2022-02-02 | installer: Use new installer-log-line everywhere....* gnu/installer.scm (installer-program)
* gnu/installer/final.scm (install-locale)
* gnu/installer/newt.scm (init)
* gnu/installer/newt/final.scm (run-final-page)
* gnu/installer/newt/page.scm (run-form-with-clients)
* gnu/installer/newt/partition.scm (run-partitioning-page)
* gnu/installer/parted.scm (eligible-devices, mkpart,
luks-format-and-open, luks-close, mount-user-partitions,
umount-user-partitions, free-parted):
* gnu/installer/steps.scm (run-installer-steps):
* gnu/installer/utils.scm (run-command, send-to-clients): Use it.
Signed-off-by: Mathieu Othacehe <othacehe@gnu.org>
| Josselin Poiret |
| 2022-02-02 | installer: Add crash dump upload support....Suggested-by: Josselin Poiret <dev@jpoiret.xyz>
* gnu/installer/dump.scm: New file.
* gnu/installer/newt/dump.scm: New file.
* gnu/local.mk (INSTALLER_MODULES): Add them.
* gnu/installer/record.scm (<installer>)[dump-page]: New field.
* gnu/installer/steps.scm (%current-result): New variable.
(run-installer-steps): Update it.
* gnu/installer.scm (installer-program): Add tar and gip to the installer
path. Add guile-webutils and gnutls to the Guile extensions. Generate and send
the crash dump report.
* gnu/installer/newt.scm (exit-error): Add a report argument. Display the
report id.
(dump-page): New procedure.
(newt-installer): Update it.
| Mathieu Othacehe |
ro? gid))
(call-with-output-file (scope "/setgroups")
(lambda (port)
(display "deny" port))))
;; Map the user/group that created the container to the root user
;; within the container.
(call-with-output-file (scope "/uid_map")
(lambda (port)
(format port "~d ~d ~d" guest-uid uid host-uids)))
(call-with-output-file (scope "/gid_map")
(lambda (port)
(format port "~d ~d ~d" guest-gid gid host-uids)))))
(define (namespaces->bit-mask namespaces)
"Return the number suitable for the 'flags' argument of 'clone' that
corresponds to the symbols in NAMESPACES."
;; Use the same flags as fork(3) in addition to the namespace flags.
(apply logior SIGCHLD
(map (match-lambda
('cgroup CLONE_NEWCGROUP)
('mnt CLONE_NEWNS)
('uts CLONE_NEWUTS)
('ipc CLONE_NEWIPC)
('user CLONE_NEWUSER)
('pid CLONE_NEWPID)
('net CLONE_NEWNET))
namespaces)))
(define* (run-container root mounts namespaces host-uids thunk
#:key (guest-uid 0) (guest-gid 0))
"Run THUNK in a new container process and return its PID. ROOT specifies
the root directory for the container. MOUNTS is a list of <file-system>
objects that specify file systems to mount inside the container. NAMESPACES
is a list of symbols that correspond to the possible Linux namespaces: mnt,
ipc, uts, user, and net.
HOST-UIDS specifies the number of host user identifiers to map into the user
namespace. GUEST-UID and GUEST-GID specify the first UID (respectively GID)
that host UIDs (respectively GIDs) map to in the namespace."
;; The parent process must initialize the user namespace for the child
;; before it can boot. To negotiate this, a pipe is used such that the
;; child process blocks until the parent writes to it.
(match (socketpair PF_UNIX (logior SOCK_CLOEXEC SOCK_STREAM) 0)
((child . parent)
(let ((flags (namespaces->bit-mask namespaces)))
(match (clone flags)
(0
(call-with-clean-exit
(lambda ()
(close-port parent)
;; Wait for parent to set things up.
(match (read child)
('ready
(purify-environment)
(when (and (memq 'mnt namespaces)
(not (string=? root "/")))
(catch #t
(lambda ()
(mount-file-systems root mounts
#:mount-/proc? (memq 'pid namespaces)
#:mount-/sys? (memq 'net
namespaces)))
(lambda args
;; Forward the exception to the parent process.
;; FIXME: SRFI-35 conditions and non-trivial objects
;; cannot be 'read' so they shouldn't be written as is.
(write args child)
(primitive-exit 3))))
;; TODO: Manage capabilities.
(write 'ready child)
(close-port child)
(thunk))
(_ ;parent died or something
(primitive-exit 2))))))
(pid
(close-port child)
(when (memq 'user namespaces)
(initialize-user-namespace pid host-uids
#:guest-uid guest-uid
#:guest-gid guest-gid))
;; TODO: Initialize cgroups.
(write 'ready parent)
(newline parent)
;; Check whether the child process' setup phase succeeded.
(let ((message (read parent)))
(close-port parent)
(match message
('ready ;success
pid)
(((? symbol? key) args ...) ;exception
(apply throw key args))
(_ ;unexpected termination
#f)))))))))
;; FIXME: This is copied from (guix utils), which we cannot use because it
;; would pull (guix config) and all.
(define (call-with-temporary-directory proc)
"Call PROC with a name of a temporary directory; close the directory and
delete it when leaving the dynamic extent of this call."
(let* ((directory (or (getenv "TMPDIR") "/tmp"))
(template (string-append directory "/guix-directory.XXXXXX"))
(tmp-dir (mkdtemp! template)))
(dynamic-wind
(const #t)
(lambda ()
(proc tmp-dir))
(lambda ()
(false-if-exception (delete-file-recursively tmp-dir))))))
(define (wait-child-process)
"Wait for one child process and return a pair, like 'waitpid', or return #f
if there are no child processes left."
(catch 'system-error
(lambda ()
(waitpid WAIT_ANY))
(lambda args
(if (= ECHILD (system-error-errno args))
#f
(apply throw args)))))
(define (status->exit-status status)
"Reify STATUS as an exit status."
(or (status:exit-val status)
;; See <http://www.tldp.org/LDP/abs/html/exitcodes.html#EXITCODESREF>.
(+ 128 (or (status:term-sig status)
(status:stop-sig status)))))
(define* (call-with-container mounts thunk #:key (namespaces %namespaces)
(host-uids 1) (guest-uid 0) (guest-gid 0)
(relayed-signals (list SIGINT SIGTERM))
(child-is-pid1? #t)
(process-spawned-hook (const #t)))
"Run THUNK in a new container process and return its exit status; call
PROCESS-SPAWNED-HOOK with the PID of the new process that has been spawned.
MOUNTS is a list of <file-system> objects that specify file systems to mount
inside the container. NAMESPACES is a list of symbols corresponding to
the identifiers for Linux namespaces: mnt, ipc, uts, pid, user, and net. By
default, all namespaces are used.
HOST-UIDS is the number of host user identifiers to map into the container's
user namespace, if there is one. By default, only a single uid/gid, that of
the current user, is mapped into the container. The host user that creates
the container is the root user (uid/gid 0) within the container. Only root
can map more than a single uid/gid.
GUEST-UID and GUEST-GID specify the first UID (respectively GID) that host
UIDs (respectively GIDs) map to in the namespace.
RELAYED-SIGNALS is the list of signals that are \"relayed\" to the container
process when caught by its parent.
When CHILD-IS-PID1? is true, and if NAMESPACES contains 'pid', then the child
process runs directly as PID 1. As such, it is responsible for (1) installing
signal handlers and (2) reaping terminated processes by calling 'waitpid'.
When CHILD-IS-PID1? is false, a new intermediate process is created instead
that takes this responsibility.
Note that if THUNK needs to load any additional Guile modules, the relevant
module files must be present in one of the mappings in MOUNTS and the Guile
load path must be adjusted as needed."
(define thunk*
(if (and (memq 'pid namespaces)
(not child-is-pid1?))
(lambda ()
;; Behave like an init process: create a sub-process that calls
;; THUNK, and wait for child processes. Furthermore, forward
;; RELAYED-SIGNALS to the child process.
(match (primitive-fork)
(0
(call-with-clean-exit thunk))
(pid
(install-signal-handlers pid)
(let loop ()
(match (wait-child-process)
((child . status)
(if (= child pid)
(primitive-exit (status->exit-status status))
(loop)))
(#f
(primitive-exit 128))))))) ;cannot happen
thunk))
(define (periodically-schedule-asyncs)
;; XXX: In Guile there's a time window where a signal-handling async could
;; be queued without being processed by the time we enter a blocking
;; syscall like waitpid(2) (info "(guile) Signals"). This terrible hack
;; ensures pending asyncs get a chance to run periodically.
(sigaction SIGALRM (lambda _ (alarm 1)))
(alarm 1))
(define (install-signal-handlers pid)
;; Install handlers that forward signals to PID.
(define (relay-signal signal)
(false-if-exception (kill pid signal)))
(periodically-schedule-asyncs)
(for-each (lambda (signal)
(sigaction signal relay-signal))
relayed-signals))
(call-with-temporary-directory
(lambda (root)
(let ((pid (run-container root mounts namespaces host-uids thunk*
#:guest-uid guest-uid
#:guest-gid guest-gid)))
(install-signal-handlers pid)
(process-spawned-hook pid)
(match (waitpid pid)
((_ . status) status))))))
(define (container-excursion pid thunk)
"Run THUNK as a child process within the namespaces of process PID and
return the exit status, an integer as returned by 'waitpid'."
(define (namespace-file pid namespace)
(string-append "/proc/" (number->string pid) "/ns/" namespace))
(match (primitive-fork)
(0
(call-with-clean-exit
(lambda ()
(for-each (lambda (ns)
(let ((source (namespace-file (getpid) ns))
(target (namespace-file pid ns)))
;; Joining the namespace that the process already
;; belongs to would throw an error so avoid that.
;; XXX: This /proc interface leads to TOCTTOU.
(unless (string=? (readlink source) (readlink target))
(call-with-input-file source
(lambda (current-ns-port)
(call-with-input-file target
(lambda (new-ns-port)
(setns (fileno new-ns-port) 0))))))))
;; It's important that the user namespace is joined first,
;; so that the user will have the privileges to join the
;; other namespaces. Furthermore, it's important that the
;; mount namespace is joined last, otherwise the /proc mount
;; point would no longer be accessible.
'("user" "ipc" "uts" "net" "pid" "mnt"))
(purify-environment)
(chdir "/")
;; Per setns(2), changing the PID namespace only applies to child
;; processes, not to the process itself. Thus fork so that THUNK runs
;; in the right PID namespace, which also gives it access to /proc.
(match (primitive-fork)
(0 (call-with-clean-exit thunk))
(pid (primitive-exit
(match (waitpid pid)
((_ . status)
(or (status:exit-val status) 127)))))))))
(pid
(match (waitpid pid)
((_ . status)
status)))))
(define (container-excursion* pid thunk)
"Like 'container-excursion', but return the return value of THUNK."
(match (pipe)
((in . out)
;; Make sure IN and OUT are not inherited if THUNK forks + execs.
(fcntl in F_SETFD FD_CLOEXEC)
(fcntl out F_SETFD FD_CLOEXEC)
(match (container-excursion pid
(lambda ()
(close-port in)
(write (thunk) out)
(close-port out)))
(0
(close-port out)
(let ((result (read in)))
(close-port in)
result))
(_ ;maybe PID died already
(close-port out)
(close-port in)
#f)))))
