Previously, system call filtering (to prevent builders from storing files with
setuid/setgid permission bits or extended attributes) was performed using a
blocklist. While this looks simple at first, it actually carries significant
security and maintainability risks: after all, the kernel may add new syscalls
to achieve the same functionality one is trying to block, and it can even be
hard to actually add the syscall to the blocklist when building against a C
library that doesn't know about it yet. For a recent demonstration of this
happening in practice to Nix, see the introduction of fchmodat2 [0] [1].
The allowlist approach does not share the same drawback. While it does require
a rather large list of harmless syscalls to be maintained in the codebase,
failing to update this list (and roll out the update to all users) in time has
rather benign effects; at worst, very recent programs that already rely on new
syscalls will fail with an error the same way they would on a slightly older
kernel that doesn't support them yet. Most importantly, no unintended new ways
of performing dangerous operations will be silently allowed.
Another possible drawback is reduced system call performance due to the larger
filter created by the allowlist requiring more computation [2]. However, this
issue has not convincingly been demonstrated yet in practice, for example in
systemd or various browsers.
This commit tries to keep the behavior as close to unchanged as possible. Only
newer syscalls that are not supported by glibc 2.38 (as found in NixOS 23.11)
are blocked. Since this includes fchmodat2, the compatibility code added for
handling this syscall can be removed too.
[0] https://github.com/NixOS/nixpkgs/issues/300635
[1] https://github.com/NixOS/nix/issues/10424
[2] https://github.com/flatpak/flatpak/pull/4462#issuecomment-1061690607
Change-Id: I541be3ea9b249bcceddfed6a5a13ac10b11e16ad
If a nested nix-shell is run inside a nix-shell, then the outer shell's
shellHook will be passed through and run again, unless the nested shell
defines its own.
With lix's hook, this can be annoying: forgetting to exit its nix-shell,
cd'ing to another repository & entering a nested nix-shell will happily
install lix's pre-commit hook in it.
This change makes lix's hook return early in such cases.
Change-Id: I91cb6eb6668f3a8eace36ecbdb01eb367861d77b
Embarrassingly, I submitted a CL overriding submit requirements since
I thought it was spurious failures. However, the CI failure was in fact
real, and I have hopefully learned my lesson. The CI failure is that:
```
vm-test-run-nix-upgrade-nix> machine # installing 'nix-2.18.1'
vm-test-run-nix-upgrade-nix> machine # building '/nix/store/2b6fdf7wvahd00bg2ff0393bhd597a0h-user-environment.drv'...
vm-test-run-nix-upgrade-nix> machine # error: Unable to build profile. There is a conflict for the following files:
vm-test-run-nix-upgrade-nix> machine #
vm-test-run-nix-upgrade-nix> machine # /nix/store/dn6mhhr92bh3ad0n4pd1538ww88khjii-nix-2.18.1/lib/libboost_context.so
vm-test-run-nix-upgrade-nix> machine # /nix/store/w4vffn9iq0znk8bcg5i2giij90xy6db6-lix-2.90.0pre20240523_c97e171/lib/libboost_context.so
vm-test-run-nix-upgrade-nix> machine # error: builder for '/nix/store/2b6fdf7wvahd00bg2ff0393bhd597a0h-user-environment.drv' failed with exit code 1
vm-test-run-nix-upgrade-nix> machine # error: program '/nix/store/w4vffn9iq0znk8bcg5i2giij90xy6db6-lix-2.90.0pre20240523_c97e171/bin/nix-env' failed with exit code 100
```
This is definitely caused by the pname not being the same, so we had
better revert that part of the change until we know we won't regress
anything by doing this.
Fixes: https://gerrit.lix.systems/c/lix/+/1152/5
Change-Id: I0e9d573987f2819c106fb7cea87410fa75152274
This breaks downstreams linking to us on purpose to make sure that if
someone is linking to Lix they're doing it on purpose and crucially not
mixing up Nix and Lix versions in compatibility code.
We still need to fix the internal includes to follow the same schema so
we can drop the single-level include system entirely. However, this
requires a little more effort.
This adds pkg-config for libfetchers and config.h.
Migration path:
expr.hh -> lix/libexpr/expr.hh
nix/config.h -> lix/config.h
To apply this migration automatically, remove all `<nix/>` from
includes, so: `#include <nix/expr.hh>` -> `#include <expr.hh>`. Then,
the correct paths will be resolved from the tangled mess, and the
clang-tidy automated fix will work.
Then run the following for out of tree projects:
```
lix_root=$HOME/lix
(cd $lix_root/clang-tidy && nix develop -c 'meson setup build && ninja -C build')
run-clang-tidy -checks='-*,lix-fixincludes' -load=$lix_root/clang-tidy/build/liblix-clang-tidy.so -p build/ -fix src
```
Related: lix-project/nix-eval-jobs#5
Fixes: lix-project/lix#279
Change-Id: I7498e903afa6850a731ef8ce77a70da6b2b46966
Fixes#183, #110, #116.
The default flake-registry option becomes 'vendored', and refers
to a vendored flake-registry.json file in the install path.
Vendored copy of the flake-registry is from github:NixOS/flake-registry
at commit 9c69f7bd2363e71fe5cd7f608113290c7614dcdd.
Change-Id: I752b81c85ebeaab4e582ac01c239d69d65580f37
This should have been in there originally, which is our mistake,
considering that debugging CI failures is basically impossible without
it.
Change-Id: I4ab8799e6e0abca1984ed9801fe10c58200861a3
We don't need bear anymore, since we don't have any more bad build
systems that lack compile commands generation inside Lix.
Change-Id: I7809ddfd993180468f846e8cd862bdd54d5b31ec
Surely if you have unreleased changes you want them on a page right?
`officialRelease` means "this is a *release version*", which is a
reasonable case to not want it, but we are not that here.
I understand wanting to be able to turn it off for deps reasons or
something, but other than that, uhh, seems better to just turn it on
always; it is basically free compute-wise to the point we run it on
pre-commit.
Part two of fixing lix#297.
Fixes: lix-project/lix#297
Change-Id: I0f8dd1ae42458df371aef529c456e47a7ac04ae0
Now instead of a derivation overridden from Lix, we use a mkShell
derivation parameterized on an already called package.nix. This also
lets callPackage take care of the buildPackages distinction for the
devShell.
Change-Id: I5ddfec40d83fa6136032da7606fe6d3d5014ef42
Because of an objc quirk[1], calling curl_global_init for the first time
after fork() will always result in a crash.
Up until now the solution has been to set
OBJC_DISABLE_INITIALIZE_FORK_SAFETY for every nix process to ignore
that error.
This is less than ideal because we were setting it in package.nix,
which meant that running nix tests locally would fail because
that variable was not set.
Instead of working around that error we address it at the core -
by calling curl_global_init inside initLibStore, which should mean
curl will already have been initialized by the time we try to do so in
a forked process.
[1] 01edf1705f/runtime/objc-initialize.mm (L614-L636)
Change-Id: Icf26010a8be655127cc130efb9c77b603a6660d0
This has the following downsides:
* you cannot build Lix against nixos-unstable.
* this will immediately break as soon as libseccomp will hit
nixos-23.11 (given that people will probably use the package.nix via
our overlay or override nixpkgs via `follows`).
Hence, removing the assert again and add a better FIXME comment.
Change-Id: I284e10cf08e1873fef70ed869a1638aa89792422
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
is 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 added a small regression-test to the setuid integration-test that
attempts to set the suid bit on a file using the fchmodat2 syscall.
I confirmed that the test fails without the change in
local-derivation-goal.
Additionally, we require libseccomp 2.5.5 or greater now: as it turns
out, libseccomp maintains an internal syscall table and
validates each rule against it. This means that when using libseccomp
2.5.4 or older, one may pass `452` as syscall number against it, but
since it doesn't exist in the internal structure, `libseccomp` will refuse
to create a filter for that. This happens with nixpkgs-23.11, i.e. on
stable NixOS and when building Lix against the project's flake.
To work around that
* a backport of libseccomp 2.5.5 on upstream nixpkgs has been
scheduled[3].
* the package now uses libseccomp 2.5.5 on its own already. This is to
provide a quick fix since the correct fix for 23.11 is still a staging cycle
away.
We still need the compat header though since `SCMP_SYS(fchmodat2)`
internally transforms this into `__SNR_fchmodat2` which points to
`__NR_fchmodat2` from glibc 2.39, so it wouldn't build on glibc 2.38.
The updated syscall table from libseccomp 2.5.5 is NOT used for that
step, but used later, so we need both, our compat header and their
syscall table 🤷
Relevant PRs in CppNix:
* https://github.com/NixOS/nix/pull/10591
* https://github.com/NixOS/nix/pull/10501
[1] https://github.com/NixOS/nixpkgs/issues/300635#issuecomment-2031073804
[2] https://github.com/NixOS/nixpkgs/issues/300635#issuecomment-2030844251
[3] https://github.com/NixOS/nixpkgs/pull/306070
(cherry picked from commit ba6804518772e6afb403dd55478365d4b863c854)
Change-Id: I6921ab5a363188c6bff617750d00bb517276b7fe
Meson cross files layer, the last value of each key takes effect.
https: //mesonbuild.com/Machine-files.html#loading-multiple-machine-files
Change-Id: I22d886f71cd51f0ce520d3fc22aed4bcf074bb91
This commit makes Meson the default buildsystem for Lix.
The Make buildsystem is now deprecated and will be removed soon, but has
not yet, which will be done in a later commit when all seems good. The
mesonBuild jobs have been removed, and have not been replaced with
equivalent jobs to ensure the Make buildsystem still works.
The full, new commands in a development shell are:
$ meson setup ./build "--prefix=$out" $mesonFlags
(A simple `meson setup ./build` will also build, but will do a different
thing, not having the settings from package.nix applied.)
$ meson compile -C build
$ meson test -C build --suite=check
$ meson install -C build
$ meson test -C build --suite=installcheck
(Check and installcheck may both be done after install, allowing you to
omit the --suite argument entirely, but this is the order package.nix
runs them in.)
If tests fail and Meson helpfully has no output for why, use the
`--print-error-logs` option to `meson test`. Why this is not the default
I cannot explain.
If you change a setting in the buildsystem, most cases will
automatically regenerate the Meson configuration, but some cases, like
trying to build a specific target whose name is new to the buildsystem
(e.g. `meson compile -C build src/libmelt/libmelt.dylib`, when
`libmelt.dylib` did not exist as a target the last time the buildsystem
was generated), then you can reconfigure using new settings but
existing options, and only recompiling stuff affected by the changes:
$ meson setup --reconfigure build
Note that changes to the default values in `meson.options` or in the
`default_options :` argument to project() are NOT propagated with
`--reconfigure`.
If you want a totally clean build, you can use:
$ meson setup --wipe build
That will work regardless of if `./build` exists or not.
Specific, named targets may be addressed in
`meson build -C build <target>` with the "target ID" if there is one,
which is the first string argument passed to target functions that
have one, and unrelated to the variable name, e.g.:
libexpr_dylib = library('nixexpr', …)
can be addressed with:
$ meson compile -C build nixexpr
All targets may be addressed as their output, relative to the build
directory, e.g.:
$ meson compile -C build src/libexpr/libnixexpr.so
But Meson does not consider intermediate files like object files
targets. To build a specific object file, use Ninja directly and
specify the output file relative to the build directory:
$ ninja -C build src/libexpr/libnixexpr.so.p/nixexpr.cc.o
To inspect the canonical source of truth on what the state of the
buildsystem configuration is, use:
$ meson introspect
Have fun!
Change-Id: Ia3e7b1e6fae26daf3162e655b4ded611a5cd57ad
This should fix cross compilation in the base case, but this is
difficult to test as cross compilation is broken in many different
places right now. This should bring Meson back up to cross parity with
the Make buildsystem though.
Change-Id: If09be8142d1fc975a82b994143ff35be1297dad8
This commit adds the capability for building the Doxygen internal API
docs in the Meson buildsystem, and also makes doing so the default for
the internal-api-docs hydra job. Aside from the /nix-support directory,
which differed only by the hash part of a store path, the outputs of
hydraJobs.internal-api-docs before and after this commit were
bit-for-bit identical on my machine.
Change-Id: I98f0017891c25b06866c15f7652fe74f706ec8e1
package.nix previously needed this callPackage'd externally, which
didn't make a lot of sense to us since this is an internal dependency.
Thus we changed it to make it more self contained.
Change-Id: I4935bc0bc80e1a132bc9b1519e917791da95037c
The following command is now sufficient to build Lix from outside of the
flake:
nix-build -E 'let pkgs = import <nixpkgs> { }; in pkgs.callPackage
./package.nix { build-release-notes = false; nix-doc = pkgs.callPackage
./nix-doc/package.nix { }; }'
Change-Id: Ie6b14b446480ac07c7266d4fba20042b04cc35b9
In our view it really doesn't make sense to not have this in in
package.nix in some way. These patches aren't just for performance or
something -- Lix flat out doesn't build without these patches.
(Arguably that makes them a buildsystem responsibility as well, but that
can wait for when we're ready to start adding subproject fallback
dependency resolution to Meson.)
This is a step towards making `package.nix` more self-sufficient and
`callPackage`able without excessive external logic.
With this change the following command is enough to build Lix from out
of the flake:
nix-build -E 'let pkgs = import <nixpkgs> { }; in pkgs.callPackage
./package.nix { build-release-notes = false; inherit (pkgs.lib) fileset;
nix-doc = pkgs.callPackage ./nix-doc/package.nix { }; }'
Change-Id: Ia37fe8171f87d3293033de8be07d9bab12716f1d
Commit c21d11ac0 "docs: replace sed invocation with an mdbook
preprocessor for @docroot@" added a direct build dependency on Python.
This has been accidentally working so far because Python is already a
*transitive* dependency of Lix's derivation.
Change-Id: I32d6b4f2665dbbfad7014613457dd58aa4ec73da
For a long time `nix repl` has supported displaying documentation set on
builtins, however, it has long been convention to use Markdown comments
on Nix functions themselves for documentation. This exposes that
information to `nix repl` users in a nice and formatted way.
NixOS/rfcs#145 doc-comments are primarily what this feature is intended
to consume, however, support for lambda documentation in the repl is
experimental. We do our best effort to support the RFC here.
These changes are based on [the nix-doc library](https://github.com/lf-/nix-doc) and
are licensed under the terms described in the relevant source files.
Change-Id: Ic6fe947d39a22540705d890737e336c4720b0a22
Functional tests can be run with
`meson test -C build --suite installcheck`.
Notably, functional tests must be run *after* running `meson install`
(Lix's derivation runs the installcheck suite in installCheckPhase so it
does this correctly), due to some quirks between Meson and the testing
system.
As far as I can tell the functional tests are meant to be run after
installing anyway, but unfortunately I can't transparently make
`meson test --suite installcheck` depend on the install targets.
The script that runs the functional tests, meson/run-test.py, checks
that `meson install` has happened and fails fast with a (hopefully)
helpful error message if any of the functional tests are run before
installing.
TODO: this change needs reflection in developer documentation
Change-Id: I8dcb5fdfc0b6cb17580973d24ad930abd57018f6
hacking changelog-d to support not just github but also forgejo and
gerrit is a lot more complicated than it's worth, even moreso since
the entire thing can just as well be done with ~60 lines of python.
this new script is also much cheaper to instantiate (being python),
so having it enabled in all shells is far less of a hassle.
we've also adjusted existing release notes that referenced a gerrit
cl to auto-link to the cl in question, making the diff a bit bigger
closes lix-project/lix#176
Change-Id: I8ba7dd0070aad9ba4474401731215fcf5d9d2130
Unit tests can be run with `meson test -C build --suite check`.
`--suite check` is optional, as right now that's the only test suite,
but when functional tests are added those will be in a separate suite.
Change-Id: I7f22f1cde4b489b3cdb5f9a36a544f0c409fcc1f
This commit adds several meson.build, which successfully build and
install Lix executables, libraries, and headers. Meson does not yet
build docs, Perl bindings, or run tests, which will be added in
following commits. As such, this commit does not remove the existing
build system, or make it the default, and also as such, this commit has
several FIXMEs and TODOs as notes for what should be done before the
existing autoconf + make buildsystem can be removed and Meson made the
default. This commit does not modify any source files.
A Meson-enabled build is also added as a Hydra job, and to
`nix flake check`.
Change-Id: I667c8685b13b7bab91e281053f807a11616ae3d4
this lets us set per-test-program environment variables rather than only
a single, global default. this was supported in nix originally but
might've gone partially missing in the upstream backports process?
Change-Id: Iad0919841b1b6d11e0b7ebd3920449a62f544e77
The src fileset, preConfigure, and separateDebugInfo also respond to doBuild if its overridden
This commit is logically just a continuation of the previous commit's
refactor, but exists separately to delineate when the core Nix
derivation hash changed (this commit).
Change-Id: I67a61bc9608d91b6a833ebc5c3894b2d2e694050
This series takes a somewhat different approach from the flake rework
done in NixOS/nix. The package.nix here does not provide callPackage
options for all the various settings in the build, and instead the other
places Nix derivations are used (like internal-api-docs) will .overrideAttrs
the normal Nix package derivation. This more closely matches how these
things were structured originally, and results in less churn and more
atomicity in these changes.
In the future, package.nix likely will migrate to have more build
options in the callPackage arguments, but we are also planning to
rewrite the build system anyway.
Change-Id: I170c4e5a4184bab62e1fd75e56db876d4ff116cf