From patchwork Wed Oct 7 21:57:24 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Ludovic_Court=C3=A8s?= X-Patchwork-Id: 24503 Return-Path: X-Original-To: patchwork@mira.cbaines.net Delivered-To: patchwork@mira.cbaines.net Received: by mira.cbaines.net (Postfix, from userid 113) id 87EE427BBE8; Wed, 7 Oct 2020 22:58:13 +0100 (BST) X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on mira.cbaines.net X-Spam-Level: X-Spam-Status: No, score=-2.9 required=5.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_MSPIKE_H4,RCVD_IN_MSPIKE_WL,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.2 Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mira.cbaines.net (Postfix) with ESMTPS id 8A0B627BBE9 for ; Wed, 7 Oct 2020 22:58:09 +0100 (BST) Received: from localhost ([::1]:50694 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kQHRo-0004RN-Ld for patchwork@mira.cbaines.net; Wed, 07 Oct 2020 17:58:08 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:58688) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kQHRi-0004R8-Pf for guix-patches@gnu.org; Wed, 07 Oct 2020 17:58:02 -0400 Received: from debbugs.gnu.org ([209.51.188.43]:46734) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1kQHRi-0004J8-G3; Wed, 07 Oct 2020 17:58:02 -0400 Received: from Debian-debbugs by debbugs.gnu.org with local (Exim 4.84_2) (envelope-from ) id 1kQHRi-0005M9-FT; Wed, 07 Oct 2020 17:58:02 -0400 X-Loop: help-debbugs@gnu.org Subject: [bug#43857] Supporting chroot builds on GNU/Hurd Resent-From: Ludovic =?utf-8?q?Court=C3=A8s?= Original-Sender: "Debbugs-submit" Resent-CC: janneke@gnu.org, guix-patches@gnu.org Resent-Date: Wed, 07 Oct 2020 21:58:02 +0000 Resent-Message-ID: Resent-Sender: help-debbugs@gnu.org X-GNU-PR-Message: report 43857 X-GNU-PR-Package: guix-patches X-GNU-PR-Keywords: To: 43857@debbugs.gnu.org Cc: Jan Nieuwenhuizen X-Debbugs-Original-To: guix-patches@gnu.org X-Debbugs-Original-Xcc: Jan Nieuwenhuizen Received: via spool by submit@debbugs.gnu.org id=B.160210785720556 (code B ref -1); Wed, 07 Oct 2020 21:58:02 +0000 Received: (at submit) by debbugs.gnu.org; 7 Oct 2020 21:57:37 +0000 Received: from localhost ([127.0.0.1]:58280 helo=debbugs.gnu.org) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1kQHRE-0005LP-PL for submit@debbugs.gnu.org; Wed, 07 Oct 2020 17:57:37 -0400 Received: from lists.gnu.org ([209.51.188.17]:38176) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1kQHR9-0005LE-UZ for submit@debbugs.gnu.org; Wed, 07 Oct 2020 17:57:31 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:58610) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kQHR9-0003t0-La for guix-patches@gnu.org; Wed, 07 Oct 2020 17:57:27 -0400 Received: from fencepost.gnu.org ([2001:470:142:3::e]:52899) by eggs.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kQHR9-00048U-CI for guix-patches@gnu.org; Wed, 07 Oct 2020 17:57:27 -0400 Received: from [2a01:e0a:1d:7270:af76:b9b:ca24:c465] (port=49304 helo=ribbon) by fencepost.gnu.org with esmtpsa (TLS1.2:RSA_AES_256_CBC_SHA1:256) (Exim 4.82) (envelope-from ) id 1kQHR7-0003fe-OE for guix-patches@gnu.org; Wed, 07 Oct 2020 17:57:26 -0400 From: Ludovic =?utf-8?q?Court=C3=A8s?= X-URL: http://www.fdn.fr/~lcourtes/ X-Revolutionary-Date: 16 =?utf-8?q?Vend=C3=A9miaire?= an 229 de la =?utf-8?q?R=C3=A9volution?= X-PGP-Key-ID: 0x090B11993D9AEBB5 X-PGP-Key: http://www.fdn.fr/~lcourtes/ludovic.asc X-PGP-Fingerprint: 3CE4 6455 8A84 FDC6 9DB4 0CFB 090B 1199 3D9A EBB5 X-OS: x86_64-pc-linux-gnu Date: Wed, 07 Oct 2020 23:57:24 +0200 Message-ID: <87sgapsnqz.fsf@gnu.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.1 (gnu/linux) MIME-Version: 1.0 X-BeenThere: debbugs-submit@debbugs.gnu.org X-Mailman-Version: 2.1.18 Precedence: list X-BeenThere: guix-patches@gnu.org List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: guix-patches-bounces+patchwork=mira.cbaines.net@gnu.org Sender: "Guix-patches" X-getmail-retrieved-from-mailbox: Patches Hello! The patch below is an attempt at supporting “chroot builds” on GNU/Hurd; it’s “almost working”. The main feature we need is firmlinks (or “bind mounts”) and commenting out Linux-specific things (private bind mounts, ‘pivot_root’, etc.). The patch introduces a ‘firmlink’ function that creates a bind mount on GNU/Linux and otherwise spawns the /hurd/firmlink translator. It also adjusts ‘deletePath’ to remove any active translators from files it’s about to delete, the goal being to terminate those firmlink translators. (Apparently that code isn’t reached yet though.) The set of /dev nodes firmlinked into the chroot is reduced compared to GNU/Linux; I added /servers, meaning that /servers is firmlinked as is, which is not ideal (see below). With this patch, I can run “guix build hello --check” in a chroot… but it eventually hangs somewhere in ‘DerivationGoal::buildDone’ (I presume) once the build has completed. It leaves behind it all its firmlink processes: --8<---------------cut here---------------start------------->8--- root@childhurd ~# ps --width=200 aux|grep firmlink root 16426 120.0 0.0 147M 616K p1 RNm 11:38PM 0:00.00 grep --color=auto firmlink root 11191 0.0 0.0 147M 888K - S8--- This has yet to be debugged. :-) Apart from that, this raises the question of what to put in the build environment. As written in the blog post about childhurds that should go out tomorrow, on GNU/Linux, we do not include any piece of userland software in the environment. But here, we’d be doing just that: running Hurd translators that are not specified as derivation inputs. It’s OK for /dev/null, but maybe questionable for /servers/socket/*. Regarding /servers, we’ll probably want to spawn separate servers (a separate /servers/proc would give up a new “PID namespace”.) Should that be done magically by the daemon, or should we leave it up to build processes, so that build processes really specify all the user-land software they depend on? We could imagine a new phase in ‘gnu-build-system’, on GNU/Hurd, that would start by setting up a bunch of translators. Food for thought… As a first step, we can firmlink it from the host, with an eye towards “doing it right”. I felt a need to hack on this as I was investigating an util-linux test failure in a ‘--disable-chroot’ setup: the test would find /proc and would later fail for some reason. Had /proc been missing from the build environment (as is the case with this patch), the test would have been skipped (it explicitly handles that case). I think we’d rather not fiddle too much with test suites until we have defined what’s available in the default build environment. Thoughts? For the record, I’ve been testing this by: 1. Adding ‘hurd’ as an input to the ‘guix’ package. 2. Cross-building the daemon using code from my branch: ~/src/guix/pre-inst-env guix build --with-git-url=guix-daemon=$PWD --with-branch=guix-daemon=wip-hurd-chroot --target=i586-pc-gnu -e '(@ (gnu packages package-management) guix-daemon)' 3. Sending it over to the childhurd: guix copy --to=localhost:10022 /gnu/store/… 4. Running it in the childhurd with: GUIX=/run/current-system/profile/bin/guix /gnu/store/…-guix-daemon-git.wip-hurd-chroot/bin/guix-daemon --build-users-group=guixbuild --disable-deduplication I guess I should probably go ahead and do everything natively in the childhurd, but I thought I’d share my weird workflow in case that gives me a chance to participate in some weirdness contest. Ludo’. From 1887d0dee0031df0de117b3a6339495504b4b489 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Ludovic=20Court=C3=A8s?= Date: Tue, 6 Oct 2020 23:53:24 +0200 Subject: [PATCH] DRAFT daemon: Support chroot builds on GNU/Hurd. * nix/libutil/util.cc (firmlink): New functions. (_deletePath) [__GNU__]: Check whether a translator is set on PATH. Call 'fsys_goaway' if this is the case. * nix/libutil/util.hh (firmlink): New declaration. * nix/libstore/build.cc (CHROOT_ENABLED): Define to 1. Error out when both __GNU__ and __linux__ are undefined. (DerivationGoal::runChild): Remove special treatment of /proc. Use 'firmlink' instead of 'mount' with MS_BIND. Wrap /proc, /dev/shm, /dev/pts, and /proc/self handling in #ifdef __linux__. Same for 'pivot_root' call. * config-daemon.ac: Set and substitute 'HURD_LIBS'. * nix/local.mk (guix_daemon_LDADD): Add $(HURD_LIBS). --- config-daemon.ac | 13 ++++ nix/libstore/build.cc | 43 +++++++++---- nix/libutil/util.cc | 139 ++++++++++++++++++++++++++++++++++++++++++ nix/libutil/util.hh | 3 + nix/local.mk | 3 +- 5 files changed, 189 insertions(+), 12 deletions(-) diff --git a/config-daemon.ac b/config-daemon.ac index 50ead355a8..bdaee82fb8 100644 --- a/config-daemon.ac +++ b/config-daemon.ac @@ -38,6 +38,19 @@ if test "x$guix_build_daemon" = "xyes"; then AC_DEFINE_UNQUOTED([SYSTEM], ["$guix_system"], [Guix host system type--i.e., platform and OS kernel tuple.]) + dnl On GNU/Hurd guix-daemon depends on libfshelp. + case "$guix_system" in + *-gnu) + AC_CHECK_LIB([fshelp], [fshelp_start_translator]) + if test "x$ac_cv_lib_fshelp_fshelp_start_translator" != "xyes"; then + AC_MSG_ERROR([libfshelp (GNU Hurd) could not be found]) + fi + HURD_LIBS="-lfshelp";; + *) + HURD_LIBS="";; + esac + AC_SUBST([HURD_LIBS]) + case "$LIBGCRYPT_PREFIX" in no) LIBGCRYPT_CFLAGS="" diff --git a/nix/libstore/build.cc b/nix/libstore/build.cc index ccec513d8d..7151932403 100644 --- a/nix/libstore/build.cc +++ b/nix/libstore/build.cc @@ -52,7 +52,13 @@ #endif -#define CHROOT_ENABLED HAVE_CHROOT && HAVE_SYS_MOUNT_H && defined(MS_BIND) && defined(MS_PRIVATE) +/* Chroot builds are supported both on GNU/Linux and on GNU/Hurd. */ +#if defined __linux__ || defined __GNU__ +# define CHROOT_ENABLED 1 +#else +# error unsupported operating system +#endif + #define CLONE_ENABLED defined(CLONE_NEWNS) #if defined(SYS_pivot_root) @@ -1991,6 +1997,7 @@ void DerivationGoal::runChild() if (setdomainname(domainname, sizeof(domainname)) == -1) throw SysError("cannot set domain name"); +#ifdef __linux__ /* Make all filesystems private. This is necessary because subtrees may have been mounted as "shared" (MS_SHARED). (Systemd does this, for instance.) Even @@ -2007,27 +2014,30 @@ void DerivationGoal::runChild() different filesystem from /, as needed for pivot_root. */ if (mount(chrootRootDir.c_str(), chrootRootDir.c_str(), 0, MS_BIND, 0) == -1) throw SysError(format("unable to bind mount ‘%1%’") % chrootRootDir); +#endif /* Set up a nearly empty /dev, unless the user asked to bind-mount the host /dev. */ Strings ss; if (dirsInChroot.find("/dev") == dirsInChroot.end()) { +#ifdef __linux__ createDirs(chrootRootDir + "/dev/shm"); createDirs(chrootRootDir + "/dev/pts"); - ss.push_back("/dev/full"); -#ifdef __linux__ + createSymlink("/proc/self/fd", chrootRootDir + "/dev/fd"); + createSymlink("/proc/self/fd/0", chrootRootDir + "/dev/stdin"); + createSymlink("/proc/self/fd/1", chrootRootDir + "/dev/stdout"); + createSymlink("/proc/self/fd/2", chrootRootDir + "/dev/stderr"); + ss.push_back("/dev/tty"); if (pathExists("/dev/kvm")) ss.push_back("/dev/kvm"); +#elif __GNU__ + ss.push_back("/servers"); #endif + ss.push_back("/dev/full"); ss.push_back("/dev/null"); ss.push_back("/dev/random"); - ss.push_back("/dev/tty"); ss.push_back("/dev/urandom"); ss.push_back("/dev/zero"); - createSymlink("/proc/self/fd", chrootRootDir + "/dev/fd"); - createSymlink("/proc/self/fd/0", chrootRootDir + "/dev/stdin"); - createSymlink("/proc/self/fd/1", chrootRootDir + "/dev/stdout"); - createSymlink("/proc/self/fd/2", chrootRootDir + "/dev/stderr"); } /* Fixed-output derivations typically need to access the @@ -2049,7 +2059,7 @@ void DerivationGoal::runChild() struct stat st; Path source = i->second; Path target = chrootRootDir + i->first; - if (source == "/proc") continue; // backwards compatibility + debug(format("bind mounting `%1%' to `%2%'") % source % target); if (stat(source.c_str(), &st) == -1) throw SysError(format("getting attributes of path `%1%'") % source); @@ -2059,10 +2069,11 @@ void DerivationGoal::runChild() createDirs(dirOf(target)); writeFile(target, ""); } - if (mount(source.c_str(), target.c_str(), "", MS_BIND, 0) == -1) + if (firmlink(source, target) == -1) throw SysError(format("bind mount from `%1%' to `%2%' failed") % source % target); } +#ifdef __linux__ /* Bind a new instance of procfs on /proc to reflect our private PID namespace. */ createDirs(chrootRootDir + "/proc"); @@ -2090,11 +2101,16 @@ void DerivationGoal::runChild() Linux versions, it is created with permissions 0. */ chmod_(chrootRootDir + "/dev/pts/ptmx", 0666); } +#elif __GNU__ + /* Do not mount things that are implemented in user land: /proc, + /dev/shm, /dev/pts, etc. */ +#endif /* Do the chroot(). */ if (chdir(chrootRootDir.c_str()) == -1) throw SysError(format("cannot change directory to '%1%'") % chrootRootDir); +#ifdef __linux__ if (mkdir("real-root", 0) == -1) throw SysError("cannot create real-root directory"); @@ -2109,8 +2125,13 @@ void DerivationGoal::runChild() if (rmdir("real-root") == -1) throw SysError("cannot remove real-root directory"); - } +#elif __GNU__ + if (chroot(".") == -1) + throw SysError(format("cannot change root directory to '%1%'") % chrootRootDir); + #endif + } +#endif // CHROOT_ENABLED if (chdir(tmpDirInSandbox.c_str()) == -1) throw SysError(format("changing into `%1%'") % tmpDir); diff --git a/nix/libutil/util.cc b/nix/libutil/util.cc index 59a2981359..b49a17a6eb 100644 --- a/nix/libutil/util.cc +++ b/nix/libutil/util.cc @@ -23,6 +23,41 @@ #include #endif +#if HAVE_SYS_MOUNT_H +#include +#endif + +#ifdef __GNU__ + +extern "C" { + +/* XXX: uses 'new' as a parameter name. Work around it. */ +# define new new_param + +# include +# include +# include +# include + +# undef new + +/* XXX: is not C++-compatible. Copy these declarations to work + around it. */ + +typedef error_t (*fshelp_open_fn_t) (int flags, + file_t *node, + mach_msg_type_name_t *node_type, + task_t, void *cookie); + +extern error_t +fshelp_start_translator (fshelp_open_fn_t underlying_open_fn, void *cookie, + char *name, char *argz, int argz_len, + int timeout, fsys_t *control); + +} + +# define _HURD_FIRMLINK _HURD "firmlink" +#endif extern char * * environ; @@ -214,6 +249,89 @@ bool isLink(const Path & path) return S_ISLNK(st.st_mode); } +#if __linux__ + +int firmlink(const Path &source, const Path &target) +{ + return mount(source.c_str(), target.c_str(), "", MS_BIND, 0); +} + +#elif __GNU__ + +static error_t return_node (int flags, + mach_port_t *underlying, + mach_msg_type_name_t *underlying_type, + task_t task, void *node) +{ + *underlying = * (mach_port_t *) node; + *underlying_type = MACH_MSG_TYPE_COPY_SEND; + + return ESUCCESS; +} + +int firmlink(const Path &source, const Path &target) +{ + static char firmlink[] = _HURD_FIRMLINK; + char *arg_vec[] = { firmlink, (char *) source.c_str (), NULL }; + char *args = NULL; + size_t args_len; + + error_t err; + file_t target_file = MACH_PORT_NULL; + + printMsg (lvlChatty, format("creating firmlink from '%1%' to '%2%'") + % source % target); + + target_file = file_name_lookup (target.c_str (), O_NOTRANS, 0); + if (! MACH_PORT_VALID (target_file)) { + printMsg (lvlChatty, format("firmlink target '%s' unavailable: %s") + % target % strerror (errno)); + goto fail; + } + + err = argz_create (arg_vec, &args, &args_len); + if (err != 0) goto fail; + + mach_port_t control; + err = fshelp_start_translator (return_node, &target_file, + firmlink, args, args_len, + 3000, &control); + if (err) { + printMsg (lvlChatty, format("failed to start '%s' translator: %s") % + firmlink % strerror(errno)); + goto fail; + } + + free ((void *) args); + args = NULL; + + err = (error_t) file_set_translator (target_file, 0, FS_TRANS_SET, 0, + NULL, 0, + control, MACH_MSG_TYPE_COPY_SEND); + mach_port_deallocate (mach_task_self (), control); + mach_port_deallocate (mach_task_self (), target_file); + + if (err) { + printMsg (lvlChatty, format("failed to set '%s' translator on node '%s': %s") % + firmlink % target % strerror(errno)); + goto fail; + } + + return err; + +fail: + int saved_errno = errno; + if (MACH_PORT_VALID (target_file)) + mach_port_deallocate (mach_task_self (), target_file); + if (args != NULL) + free ((void *) args); + errno = saved_errno; + return -1; +} + +#elif +# error unsupported operating system +#endif DirEntries readDirectory(const Path & path) { @@ -311,6 +429,27 @@ static void _deletePath(const Path & path, unsigned long long & bytesFreed, size printMsg(lvlVomit, format("%1%") % path); +#ifdef __GNU__ + /* Check whether there's an active translator on PATH--typically + /hurd/firmlink. If there is one, let it go away. */ + { + file_t file = file_name_lookup (path.c_str (), O_NOTRANS, 0); + if (MACH_PORT_VALID (file)) { + fsys_t fsys; + int err = file_get_translator_cntl (file, &fsys); + mach_port_deallocate (mach_task_self (), file); + if (err == 0) { + /* There's a translator, tell it to leave. */ + err = fsys_goaway (fsys, FSYS_GOAWAY_FORCE | FSYS_GOAWAY_RECURSE); + mach_port_deallocate (mach_task_self (), fsys); + if (err != 0) { + throw SysError(format("removing translator from '%1%'") % path); + } + } + } + } +#endif + #ifdef HAVE_STATX # define st_mode stx_mode # define st_size stx_size diff --git a/nix/libutil/util.hh b/nix/libutil/util.hh index 13cff44316..353c758895 100644 --- a/nix/libutil/util.hh +++ b/nix/libutil/util.hh @@ -62,6 +62,9 @@ Path readLink(const Path & path); bool isLink(const Path & path); +/* Make TARGET a firmlink (aka. "bind mount") to SOURCE. */ +int firmlink(const Path & source, const Path & target); + /* Read the contents of a directory. The entries `.' and `..' are removed. */ struct DirEntry diff --git a/nix/local.mk b/nix/local.mk index 2bb01041b9..782e2c85cc 100644 --- a/nix/local.mk +++ b/nix/local.mk @@ -124,7 +124,8 @@ guix_daemon_CPPFLAGS = \ guix_daemon_LDADD = \ libstore.a libutil.a libformat.a -lz \ - $(SQLITE3_LIBS) $(LIBGCRYPT_LIBS) + $(SQLITE3_LIBS) $(LIBGCRYPT_LIBS) \ + $(HURD_LIBS) guix_daemon_headers = \ %D%/nix-daemon/shared.hh -- 2.28.0