wroclaw-git-backups/nix
1
0
Fork 0
mirror of https://github.com/NixOS/nix synced 2025-07-02 21:51:50 +02:00
Code Activity

Use chroots for all derivations

Browse source 
If ‘build-use-chroot’ is set to ‘true’, fixed-output derivations are
now also chrooted. However, unlike normal derivations, they don't get
a private network namespace, so they can still access the
network. Also, the use of the ‘__noChroot’ derivation attribute is
no longer allowed.

Setting ‘build-use-chroot’ to ‘relaxed’ gives the old behaviour.
This commit is contained in:
Eelco Dolstra 2015-02-23 15:41:41 +01:00
parent 15d2d3c34e
commit 99897f6979
4 changed files with 56 additions and 30 deletions
Download patch file Download diff file Expand all files Collapse all files

47
src/libstore/build.cc
View file

@ -1768,12 +1768,20 @@ void DerivationGoal::startBuilder()
functions like fetchurl (which needs a proper /etc/resolv.conf)
work properly. Purity checking for fixed-output derivations
is somewhat pointless anyway. */
useChroot = settings.useChroot;
if (fixedOutput) useChroot = false;
/* Hack to allow derivations to disable chroot builds. */
if (get(drv.env, "__noChroot") == "1") useChroot = false;
{
string x = settings.get("build-use-chroot", string("false"));
if (x != "true" && x != "false" && x != "relaxed")
throw Error("option ‘build-use-chroot’ must be set to one of ‘true’, ‘false’ or ‘relaxed’");
if (x == "true") {
if (get(drv.env, "__noChroot") == "1")
throw Error(format("derivation ‘%1%’ has ‘__noChroot’ set, but that's not allowed when ‘build-use-chroot’ is ‘true’") % drvPath);
useChroot = true;
}
else if (x == "false")
useChroot = false;
else if (x == "relaxed")
useChroot = !fixedOutput && get(drv.env, "__noChroot") != "1";
}
if (useChroot) {
/* Allow a user-configurable set of directories from the
@ -1856,7 +1864,8 @@ void DerivationGoal::startBuilder()
% (buildUser.enabled() ? buildUser.getGID() : getgid())).str());
/* Create /etc/hosts with localhost entry. */
writeFile(chrootRootDir + "/etc/hosts", "127.0.0.1 localhost\n");
if (!fixedOutput)
writeFile(chrootRootDir + "/etc/hosts", "127.0.0.1 localhost\n");
/* Make the closure of the inputs available in the chroot,
rather than the whole Nix store. This prevents any access
@ -1964,7 +1973,9 @@ void DerivationGoal::startBuilder()
- The private network namespace ensures that the builder
cannot talk to the outside world (or vice versa). It
only has a private loopback interface.
only has a private loopback interface. (Fixed-output
derivations are not run in a private network namespace
to allow functions like fetchurl to work.)
- The IPC namespace prevents the builder from communicating
with outside processes using SysV IPC mechanisms (shared
@ -1983,8 +1994,9 @@ void DerivationGoal::startBuilder()
*/
Pid helper = startProcess([&]() {
char stack[32 * 1024];
pid_t child = clone(childEntry, stack + sizeof(stack) - 8,
CLONE_NEWPID | CLONE_NEWNS | CLONE_NEWNET | CLONE_NEWIPC | CLONE_NEWUTS | CLONE_PARENT | SIGCHLD, this);
int flags = CLONE_NEWPID | CLONE_NEWNS | CLONE_NEWIPC | CLONE_NEWUTS | CLONE_PARENT | SIGCHLD;
if (!fixedOutput) flags |= CLONE_NEWNET;
pid_t child = clone(childEntry, stack + sizeof(stack) - 8, flags, this);
if (child == -1) {
if (errno == EINVAL)
throw SysError("cloning builder process (Linux chroot builds require 3.13 or later)");
@ -2081,10 +2093,10 @@ void DerivationGoal::runChild()
/* Set up a nearly empty /dev, unless the user asked to
bind-mount the host /dev. */
Strings ss;
if (dirsInChroot.find("/dev") == dirsInChroot.end()) {
createDirs(chrootRootDir + "/dev/shm");
createDirs(chrootRootDir + "/dev/pts");
Strings ss;
ss.push_back("/dev/full");
#ifdef __linux__
if (pathExists("/dev/kvm"))
@ -2095,13 +2107,24 @@ void DerivationGoal::runChild()
ss.push_back("/dev/tty");
ss.push_back("/dev/urandom");
ss.push_back("/dev/zero");
foreach (Strings::iterator, i, ss) dirsInChroot[*i] = *i;
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
network, so give them access to /etc/resolv.conf and so
on. */
if (fixedOutput) {
ss.push_back("/etc/resolv.conf");
ss.push_back("/etc/nsswitch.conf");
ss.push_back("/etc/services");
ss.push_back("/etc/hosts");
}
for (auto & i : ss) dirsInChroot[i] = i;
/* Bind-mount all the directories from the "host"
filesystem that we want in the chroot
environment. */