The recent fix for CVE-2024-38531 broke the sandbox on macOS
completely. As it’s not practical to use `chroot(2)` on
macOS, the build takes place in the main filesystem tree, and the
world‐unreadable wrapper directory prevents the build from accessing
its `$TMPDIR` at all.
The macOS sandbox probably shouldn’t be treated as any kind of a
security boundary in its current state, but this specific vulnerability
wasn’t possible to exploit on macOS anyway, as creating `set{u,g}id`
binaries is blocked by sandbox policy.
Locking down the build sandbox further may be a good idea in future,
but it already has significant compatibility issues. For now, restore
the previous status quo on macOS.
Thanks to @alois31 for helping me come to a better understanding of
the vulnerability.
Fixes: 1d3696f0fbCloses: #11002
- use the iterator in `CanonPath` to count `level`
- use the `CanonPath::basename` method
- use `CanonPath::root` instead of `CanonPath{""}`
- remove `Path` and `PathView`, use `std::filesystem::path` directly
Inspired by
010ff57ebb
From the original PR:
> We do not have any of these warnings appearing at the moment, but
> it seems like a good idea to enable [[nodiscard]] checking anyway.
> Once we start introducing more functions with must-use conditions we will
> need such checking, and the rust stdlib has proven them very useful.
It was added above this conditional
Worker::Worker(LocalStore & store)
: store(store)
{
/* Debugging: prevent recursive workers. */
if (working) abort();
working = true;
However, `working` has since been removed.
Source: 7f8e805c8e/src/libstore/build.cc (L2617)
The old `std::variant` is bad because we aren't adding a new case to
`FileIngestionMethod` so much as we are defining a separate concept ---
store object content addressing rather than file system object content
addressing. As such, it is more correct to just create a fresh
enumeration.
Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
Previously, the .chroot directory had permission 750 or 755 (depending
on the uid-range system feature) and was owned by root/nixbld. This
makes it possible for any nixbld user (if uid-range is disabled) or
any user (if uid-range is enabled) to inspect the contents of the
chroot of an active build and maybe interfere with it (e.g. via /tmp
in the chroot, which has 1777 permission).
To prevent this, the root is now a subdirectory of .chroot, which has
permission 700 and is owned by root/root.
Instead of running the builds under
`$TMPDIR/{unique-build-directory-owned-by-the-build-user}`, run them
under `$TMPDIR/{unique-build-directory-owned-by-the-daemon}/{subdir-owned-by-the-build-user}`
where the build directory is only readable and traversable by the daemon user.
This achieves two things:
1. It prevents builders from making their build directory world-readable
(or even writeable), which would allow the outside world to interact
with them.
2. It prevents external processes running as the build user (either
because that somehow leaked, maybe as a consequence of 1., or because
`build-users` isn't in use) from gaining access to the build
directory.
the `std::filesystem::create_directories` can fail due to insufficient
permissions. We convert this error into a `SysError` and catch it
wherever required.
#2230 broadened the scope of macOS hardlink exclusion but did not change the comments. This was a little confusing for me, so I figured the comments should be updated.
Special thanks to everyone that has worked on a Meson port so far,
@p01arst0rm and @Qyriad in particular.
Co-Authored-By: p01arst0rm <polar@ever3st.com>
Co-Authored-By: Artemis Tosini <lix@artem.ist>
Co-Authored-By: Artemis Tosini <me@artem.ist>
Co-Authored-By: Felix Uhl <felix.uhl@outlook.com>
Co-Authored-By: Jade Lovelace <lix@jade.fyi>
Co-Authored-By: Lunaphied <lunaphied@lunaphied.me>
Co-Authored-By: Maximilian Bosch <maximilian@mbosch.me>
Co-Authored-By: Pierre Bourdon <delroth@gmail.com>
Co-Authored-By: Qyriad <qyriad@qyriad.me>
Co-Authored-By: Rebecca Turner <rbt@sent.as>
Co-Authored-By: Winter <winter@winter.cafe>
Co-Authored-By: eldritch horrors <pennae@lix.systems>
Co-Authored-By: jade <lix@jade.fyi>
Co-Authored-By: julia <midnight@trainwit.ch>
Co-Authored-By: rebecca “wiggles” turner <rbt@sent.as>
Co-Authored-By: wiggles dog <rbt@sent.as>
Co-Authored-By: fricklerhandwerk <valentin@fricklerhandwerk.de>
Co-authored-by: Eli Schwartz <eschwartz93@gmail.com>
Before, `-lnixutil` was just stuck in `nix-store.pc`, but that doesn't
seem so nice.
This prepares us to distribute `libnixutil` in a separate package if we
want, but it should be a good change either way. I suspect it wasn't
done before because libutil was an extra unstable interface, but I don't
think we need worry about that. *All* the C++ is less stable than the C
(or that's the goal at least).
For what it's worth, Lix also created this pkg-config file *en passant*
during their rename:
c97e17144e (diff-3c4f60cc44a0e35444c7f45331cfa50f76637118)
1. Fix build by making the legacy SSH Storey's secret `logFD` setting
not a setting on Windows. (It doesn't make sense to specify `void *`
handles by integer cross-proccess, I don't think.)
2. Move some files that don't need to be Unix-only anymore back to their
original locations.
- Get a rump derivation goal: hook instance will come later, local
derivation goal will come after that.
- Start cleaning up the channel / waiting code with an abstraction.
By moving `host` to the config, we can do a lot further cleanups and
dedups. This anticipates a world where we always go `StoreReference` ->
`*StoreConfig` -> `Store*` rather than skipping the middle step too.
Progress on #10766
Progress on https://github.com/NixOS/hydra/issues/1164
This increases test coverage, and gets the worker protocol ready to be
used by Hydra.
Why don't we just try to use the store interface in Hydra? Well, the
problem is that the store interface works on connection pools, with each
opreation getting potentially a different connection, but the way temp
roots work requires that we keep one logical "transaction" (temp root
session) using the same connection.
The longer-term solution probably is making connections themselves
implement the store interface, but that is something that builds on
this, so I feel OK that this is not churn in the wrong direction.
Fixes#9584
We don't want to rely on how C assigns numbers for enums in the wire
format. Sure, this is totally determined by the ABI, but it obscures the
code and makes it harder to safely change the enum definition (should we
need to) without accidentally breaking the wire format.
Do this instead of an unchecked cast
I redid this to use the serialisation framework (including a unit test),
but I am keeping the reference to credit Jade for spotting the issue.
Change-Id: Icf6af7935e8f139bef36b40ad475e973aa48855c
(adapted from commit 2a7a824d83dc5fb33326b8b89625685f283a743b)
Co-Authored-By: Jade Lovelace <lix@jade.fyi>
This was accidentally removed in
e989c83b44. I restored it and also did a
few other cleanups:
- Make a static method for namespacing purposes
- Put the test files in the data dir with the other test data
- Avoid mutating globals in the machine config tests
This will be used by Hydra.
Need to decouple parsing from actually opening a store for Machine
configs.
Co-authored-by: Théophane Hufschmitt <7226587+thufschmitt@users.noreply.github.com>
Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
In particular `local://<path>` and `unix://` (without any path) now
work, and mean the same things as `local` and `daemon`, respectively. We
thus now have the opportunity to desguar `local` and `daemon` early.
This will allow me to make a change to
https://github.com/NixOS/nix/pull/9839 requested during review to
desugar those earlier.
Co-authored-by: Théophane Hufschmitt <7226587+thufschmitt@users.noreply.github.com>
1. Hydra currently queries for multiple path infos at once, so let us
make a connection item for that.
2. The minimum of the two versions should always be used, see #9584.
(The issue remains open because the daemon protocol needs to be
likewise updated.)
The JSON format no longer uses the legacy ATerm `r:` prefixing nonsese,
but separate fields.
Progress on #9866
Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
On several occasions I've found myself confused when trying to delete
a store path, because I am told it's still alive, but
nix-store --query --roots doesn't show anything. Let's save future
users this confusion by mentioning that a path might be alive due to
having referrers, not just roots.
In addition:
- Take the opportunity to add a bunch more missing hyperlinks, too.
- Remove some glossary entries that are now subsumed by dedicated pages.
We used to not be able to do this without breaking link fragments, but
now we can, so pick up where we left off.
Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
This is useful for diagnosing whether an evaluation is copying large
paths to the store. Example:
$ nix build .#packages.x86_64-linux.default --large-path-warning-threshold 1000000
warning: copied large path '/home/eelco/Dev/nix-master/' to the store (6271792 bytes)
warning: copied large path '«github:NixOS/nixpkgs/b550fe4b4776908ac2a861124307045f8e717c8e?narHash=sha256-7kkJQd4rZ%2BvFrzWu8sTRtta5D1kBG0LSRYAfhtmMlSo%3D»/' to the store (155263768 bytes)
warning: copied large path '«github:libgit2/libgit2/45fd9ed7ae1a9b74b957ef4f337bc3c8b3df01b5?narHash=sha256-oX4Z3S9WtJlwvj0uH9HlYcWv%2Bx1hqp8mhXl7HsLu2f0%3D»/' to the store (22175416 bytes)
warning: copied large path '/nix/store/z985088mcd6w23qwdlirsinnyzayagki-source' to the store (5885872 bytes)
the old `copyFile` was just a wrapper that was calling the `copy`
function. This wrapper function is removed and the `copy` function is
renamed to `copyFile`.
Building derivations is a lot harder, but the downloading goals is
portable enough.
The "common channel" code is due to Volth. I wonder if there is a way we
can factor it out into separate functions / files to avoid some
within-function CPP.
Co-authored-by: volth <volth@volth.com>
Sometimes we read a directory with children we cannot stat. It's a pitty
we even try to stat at all (wasteful) in the `DT_UNKNOWN` case, but at
least this should get rid of the failure.
This makes for shorter and more portable code.
The only tricky part is catching exceptions: I just searched for near by
`catch (Error &)` or `catch (SysError &)` and adjusted them to `catch
(std::filesystem::filesystem_error &)` according to my human judgement.
Good for windows portability; will help @siddhantk232 with his GSOC
project.
Now that SourcePath uses a SourceAccessor instead of an InputAccessor,
we can use it in function signatures instead of passing a
SourceAccessor and CanonPath separately.
Make sure that `extraSandboxProfile` is set before we check whether it's
empty or not (in the `sandbox=true` case).
Also adds a test case for this.
Co-Authored-By: Artemis Tosini <lix@artem.ist>
Co-Authored-By: Eelco Dolstra <edolstra@gmail.com>
Fix formatting violations, update blacklist to reflect moved files.
PR #10556 passed CI before the new formating rules were added, and our
CI has the race condition of allowing old results, resulting in master
getting broken.
Windows now has some basic Unix Domain Socket support, see
https://devblogs.microsoft.com/commandline/af_unix-comes-to-windows/
Building `nix daemon` on Windows I've left for later, because the daemon
currently forks per connection but this is not an option on Windows. But
we can get the client part working right away.
With Linux kernel >=6.6 & glibc 2.39 a `fchmodat2(2)` is available that
isn't filtered away by the libseccomp sandbox.
Being able to use this to bypass that restriction has surprising results
for some builds such as lxc[1]:
> With kernel ≥6.6 and glibc 2.39, lxc's install phase uses fchmodat2,
> which slips through 9b88e52846/src/libstore/build/local-derivation-goal.cc (L1650-L1663).
> The fixupPhase then uses fchmodat, which fails.
> With older kernel or glibc, setting the suid bit fails in the
> install phase, which is not treated as fatal, and then the
> fixup phase does not try to set it again.
Please note that there are still ways to bypass this sandbox[2] and this is
mostly a fix for the breaking builds.
This change works by creating a syscall filter for the `fchmodat2`
syscall (number 452 on most systems). The problem is that glibc 2.39
and seccomp 2.5.5 are needed to have the correct syscall number available
via `__NR_fchmodat2` / `__SNR_fchmodat2`, but this flake is still on
nixpkgs 23.11. To have this change everywhere and not dependent on the
glibc this package is built against, I added a header
"fchmodat2-compat.hh" that sets the syscall number based on the
architecture. On most platforms its 452 according to glibc with a few
exceptions:
$ rg --pcre2 'define __NR_fchmodat2 (?!452)'
sysdeps/unix/sysv/linux/x86_64/x32/arch-syscall.h
58:#define __NR_fchmodat2 1073742276
sysdeps/unix/sysv/linux/mips/mips64/n32/arch-syscall.h
67:#define __NR_fchmodat2 6452
sysdeps/unix/sysv/linux/mips/mips64/n64/arch-syscall.h
62:#define __NR_fchmodat2 5452
sysdeps/unix/sysv/linux/mips/mips32/arch-syscall.h
70:#define __NR_fchmodat2 4452
sysdeps/unix/sysv/linux/alpha/arch-syscall.h
59:#define __NR_fchmodat2 562
I tested the change by adding the diff below as patch to
`pkgs/tools/package-management/nix/common.nix` & then built a VM from
the following config using my dirty nixpkgs master:
{
vm = { pkgs, ... }: {
virtualisation.writableStore = true;
virtualisation.memorySize = 8192;
virtualisation.diskSize = 12 * 1024;
nix.package = pkgs.nixVersions.nix_2_21;
};
}
The original issue can be triggered via
nix build -L github:nixos/nixpkgs/d6dc19adbda4fd92fe9a332327a8113eaa843894#lxc \
--extra-experimental-features 'nix-command flakes'
however the problem disappears with this patch applied.
Closes#10424
[1] https://github.com/NixOS/nixpkgs/issues/300635#issuecomment-2031073804
[2] https://github.com/NixOS/nixpkgs/issues/300635#issuecomment-2030844251
With Nix 2.3, it was possible to pass a subpath of a store path to
exportReferencesGraph:
with import <nixpkgs> {};
let
hello = writeShellScriptBin "hello" ''
echo ${toString builtins.currentTime}
'';
in
writeClosure [ "${hello}/bin/hello" ]
This regressed with Nix 2.4, with a very confusing error message, that
presumably indicates it was unintentional:
error: path '/nix/store/3gl7kgjr4pwf03f0x70dgx9ln3bhl7zc-hello/bin/hello' is not in the Nix store
At this point many features are stripped out, but this works:
- Can run libnix{util,store,expr} unit tests
- Can run some Nix commands
Co-Authored-By volth <volth@volth.com>
Co-Authored-By Brian McKenna <brian@brianmckenna.org>
* add intermediate variables and clarifying comments
Co-authored-by: Alexander Groleau <alex@proof.construction>
Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
https://github.com/NixOS/nix/pull/10456 fixed the addition of symlink
store paths to the sandbox, but also made it so that the hardcoded
sandbox paths (like `/etc/hosts`) were now bind-mounted without
following the possible symlinks. This made these files unreadable if
there were symlinks (because the sandbox would now contain a symlink to
an unreachable file rather than the underlying file).
In particular, this broke FOD derivations on NixOS as `/etc/hosts` is a
symlink there.
Fix that by canonicalizing all these hardcoded sandbox paths before
adding them to the sandbox.
Like always declining; local builds only, as can be inferred from the
docs. (Not worth spending too many words on this pretty obvious
behavior, I think. Also, plans to remove it? https://github.com/NixOS/nix/issues/1221)
This requires moving resolveSymlinks() into SourceAccessor. Also, it
requires LocalStoreAccessor::maybeLstat() to work on parents of the
store (to avoid an error like "/nix is not in the store").
Fixes#10375.
Bind-mounting symlinks is apparently not possible, which is why the
thing was failing.
Fortunately, symlinks are small, so we can fallback to copy them at no cost.
Fix https://github.com/NixOS/nix/issues/9579
Co-authored-by: Artturin <Artturin@artturin.com>
Forcing a conditional include, vs making the headers content
conditional, I think is more maintainable.
It is also how the other platform-specific headers (like
`namespaces.hh`) have been adapted.
This introduces new utility functions to get elements from JSON — in an ergonomic way and with nice error messages if the expected type does not match.
Co-authored-by: John Ericson <John.Ericson@Obsidian.Systems>
This splits files and adds new identifiers in preperation for supporting
windows, but no Windows-specific code is actually added yet.
Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
This function is nice for more than `PosixSourceAccessor`. We can make a
few things simpler with it.
Note that the error logic slightly changes in some of the call sites, in
that we also count `ENOTDIR` and not just `ENOENT` as not having the
file, but that should be fine.
Fixes an instance of
nix: src/libutil/util.cc:139: nix::Path nix::canonPath(PathView, bool): Assertion `path != ""' failed.
... which I've been getting in one of my shells for some reason.
I have yet to find out why TMPDIR was empty, but it's no reason for
Nix to break.
In a daemon-based Nix setup, some options cannot be overridden by a
client unless the client's user is considered trusted.
Currently, if an untrusted user tries to override one of those
options, we are silently ignoring it.
This can be pretty confusing in certain situations.
e.g. a user thinks he disabled the sandbox when in reality he did not.
We are now sending a warning message letting know the user some options
have been ignored.
Related to #1761.
This is a cherry-pick of 9e0f5f803f.
The above commit has been reverted by
a59e77d9e5 to prevent spamming warnings
with experimental features, but these are now totally ignored on the
daemon side, so there's no reason for the revert any more.
It is possible to exfiltrate a file descriptor out of the build sandbox
of FODs, and use it to modify the store path after it has been
registered.
To avoid that issue, don't register the output of the build, but a copy
of it (that will be free of any leaked file descriptor).
Instead, serialize as NAR and send that over, then rehash sever side.
This is alorithmically simpler, but comes at the cost of a newer
parameter to `Store::addToStoreFromDump`.
Co-authored-by: Eelco Dolstra <edolstra@gmail.com>
Part of RFC 133
Extracted from our old IPFS branches.
Co-Authored-By: Matthew Bauer <mjbauer95@gmail.com>
Co-Authored-By: Carlo Nucera <carlo.nucera@protonmail.com>
Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
Co-authored-by: Florian Klink <flokli@flokli.de>
"hash type" -> "hash algorithm" in all comments, documentation, and
messages.
ht -> ha, [Hh]ashType -> [HhashAlgo] for all local variables and
function arguments. No API change is made.
Continuation of 5334c9c792 and 837b889c41.
The sandbox rule `(allow network* (local ip))` doesn't do what it
implies. Adding this rule permits all network traffic. We should be
matching on (remote ip "localhost:*")` instead.
No outward facing behavior is changed.
Older methods with same names that operate on on method + algo pair (for
old-style `<method>:algo`) are renamed to `*WithAlgo`.)
The functions are unit-tested in the same way the names for the hash
algorithms are tested.
* reword description of the `cores` setting
- be precise about the `builder` executable
- clearly distinguish between `builder` and job parallelism
- clarify the role of `mkDerivation` in the example
- remove prose for the default, it's shown programmatically
- mention relation to `max-jobs`
