Commit graph

78 commits

Author SHA1 Message Date
Lunaphied 41963df4a5 lix-doc: update dependencies and refactor
This updates the version of rnix used and refactors the code generally
to be more precise and capable in it's identification of both lambdas
and determining which documentation comments are attached.

Change-Id: Ib0dddabd71f772c95077f9d7654023b37a7a1fd2
2024-07-10 02:25:48 +00:00
jade f7d54cb6b1 packaging: make pegtl use the __forDefaults mechanism
This avoids needing to pass it in when callPackage'ing Lix from external
code.

Change-Id: Ie07e84a151e38614064609a2f6dbff165e193be7
2024-06-26 00:44:46 -07:00
jade 4ac2c496d4 Merge "change shebangs of all .sh scripts to bash" into main 2024-06-25 22:18:26 +00:00
jade aceef13682 Merge changes If0ddec6b,Iaa63ed18 into main
* changes:
  Add some release notes for things we did
  packaging: don't build internal api docs by default in dev shells
2024-06-25 22:16:04 +00:00
eldritch horrors e6cd67591b libexpr: rewrite the parser with pegtl instead of flex/bison
this gives about 20% performance improvements on pure parsing. obviously
it will be less on full eval, but depending on how much parsing is to be
done (e.g. including hackage-packages.nix or not) it's more like 4%-10%.

this has been tested (with thousands of core hours of fuzzing) to ensure
that the ASTs produced by the new parser are exactly the same as the old
one would have produced. error messages will change (sometimes by a lot)
and are not yet perfect, but we would rather leave this as is for later.

test results for running only the parser (excluding the variable binding
code) in a tight loop with inputs and parameters as given are promising:

  - 40% faster on lix's package.nix at 10000 iterations
  - 1.3% faster on nixpkgs all-packages.nix at 1000 iterations
  - equivalent on all of nixpkgs concatenated at 100 iterations
    (excluding invalid files, each file surrounded with parens)

more realistic benchmarks are somewhere in between the extremes, parsing
once again getting the largest uplift. other realistic workloads improve
by a few percentage points as well, notably system builds are 4% faster.

Benchmarks summary (from ./bench/summarize.jq bench/bench-*.json)
old/bin/nix --extra-experimental-features 'nix-command flakes' eval -f bench/nixpkgs/pkgs/development/haskell-modules/hackage-packages.nix
  mean:     0.408s ± 0.025s
            user: 0.355s | system: 0.033s
  median:   0.389s
  range:    0.388s ... 0.442s
  relative: 1

new/bin/nix --extra-experimental-features 'nix-command flakes' eval -f bench/nixpkgs/pkgs/development/haskell-modules/hackage-packages.nix
  mean:     0.332s ± 0.024s
            user: 0.279s | system: 0.033s
  median:   0.314s
  range:    0.313s ... 0.361s
  relative: 0.814

---

old/bin/nix --extra-experimental-features 'nix-command flakes' eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'
  mean:     6.133s ± 0.022s
            user: 5.395s | system: 0.437s
  median:   6.128s
  range:    6.099s ... 6.183s
  relative: 1

new/bin/nix --extra-experimental-features 'nix-command flakes' eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'
  mean:     5.925s ± 0.025s
            user: 5.176s | system: 0.456s
  median:   5.934s
  range:    5.861s ... 5.943s
  relative: 0.966

---

GC_INITIAL_HEAP_SIZE=10g old/bin/nix eval --extra-experimental-features 'nix-command flakes' --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'
  mean:     4.503s ± 0.027s
            user: 3.731s | system: 0.547s
  median:   4.499s
  range:    4.478s ... 4.541s
  relative: 1

GC_INITIAL_HEAP_SIZE=10g new/bin/nix eval --extra-experimental-features 'nix-command flakes' --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'
  mean:     4.285s ± 0.031s
            user: 3.504s | system: 0.571s
  median:   4.281s
  range:    4.221s ... 4.328s
  relative: 0.951

---

old/bin/nix --extra-experimental-features 'nix-command flakes' search --no-eval-cache github:nixos/nixpkgs/e1fa12d4f6c6fe19ccb59cac54b5b3f25e160870 hello
  mean:     16.475s ± 0.07s
            user: 14.088s | system: 1.572s
  median:   16.495s
  range:    16.351s ... 16.536s
  relative: 1

new/bin/nix --extra-experimental-features 'nix-command flakes' search --no-eval-cache github:nixos/nixpkgs/e1fa12d4f6c6fe19ccb59cac54b5b3f25e160870 hello
  mean:     15.973s ± 0.013s
            user: 13.558s | system: 1.615s
  median:   15.973s
  range:    15.946s ... 15.99s
  relative: 0.97

---

Change-Id: Ie66ec2d045dec964632c6541e25f8f0797319ee2
2024-06-25 12:24:58 +00:00
jade 1245340e44 packaging: don't build internal api docs by default in dev shells
These are totally available and you can just turn them on, but they have
very bad dependency tracking and thus bloat incremental change times,
which is not really ok.

Change-Id: Iaa63ed18a789e74fcb757248cd24c3b194afcc80
2024-06-24 15:57:38 -07:00
vigress8 c7af89c797 change shebangs of all .sh scripts to bash
On operating systems where /bin/sh is not Bash, some scripts are invalid
because of bashisms, and building Lix fails with errors like this:
`render-manpage.sh: 3: set: Illegal option -o pipefail`
This modifies all scripts that use a `/bin/sh` shebang to `/usr/bin/env
bash`, including currently POSIX-compliant ones, to prevent any future
confusion.

Change-Id: Ia074cc6db42d40fc59a63726f6194ea0149ea5e0
2024-06-24 14:00:43 -07:00
jade d5637ee790 devShell: guard against running from another directory
I was working on nix-eval-jobs with a dev shell with some shenanigans to
run against a locally built Lix and it was getting really annoying when
`nix develop ../lix#` was messing up my other git repo's hooks.

This is a fix via blunt force, but it is at least obvious how it works.

Change-Id: Ia29eeb5be57ab6a2c88451c00ea18a51e4dfe65e
2024-06-24 13:41:38 -07:00
jade 068576042b packaging: Move binaryTarball to a passthru attr in package.nix
This is motivated by flakes being bad and all the stuff that calls
things by "system" being utterly unable to cope with cross compilation.
So if we go shove it in package.nix it is suddenly usable from cross
contexts.

Usage:

```
nix build -L .#nix-riscv64-linux.binaryTarball
```

Change-Id: I702ebf2ac5bd9d1c57662f968b000073134df336
2024-06-13 15:14:22 -07:00
Pierre Bourdon 248ecb11af dev shell: Add bashInteractive
This was bothersome to me as a zsh+direnv user.

Change-Id: Ia5b54cc63647a5c6ced2b5412e972dac1abf8184
2024-06-12 15:34:23 -07:00
jade 479055aee8 Misc workaround removals since 24.05 upgrade
Change-Id: I9491b103333cb0e25c245199e88365ded7800d2e
2024-06-12 15:34:23 -07:00
Pierre Bourdon f7b6552699 [resubmit] flake: update nixpkgs pin 23.11->24.05 (+ boehmgc compat changes)
-- message from cl/1418 --

The boehmgc changes are bundled into this commit because doing otherwise
would require an annoying dance of "adding compatibility for < 8.2.6 and
>= 8.2.6" then updating the pin then removing the (now unneeded)
compatibility. It doesn't seem worth the trouble to me given the low
complexity of said changes.

Rebased coroutine-sp-fallback.diff patch taken from https://github.com/NixOS/nixpkgs/pull/317227

-- jade resubmit changes --

This is a resubmission of https://gerrit.lix.systems/c/lix/+/1418, which
was reverted in https://gerrit.lix.systems/c/lix/+/1432 for breaking CI
evaluation without being detected.

I have run `nix flake check -Lv` on this one before submission and it
passes on my machine and crucially without eval errors, so the CI result
should be accurate.

It seems like someone renamed forbiddenDependenciesRegex to
forbiddenDependenciesRegexes in nixpkgs and also changed the type
incompatibly. That's pretty silly, but at least it's just an eval error.

Also, `xonsh` regressed the availability of `xonsh-unwrapped`, but it
was fixed by us in https://github.com/NixOS/nixpkgs/pull/317636, which
is now in our channel, so we update nixpkgs compared to the original
iteration of this to simply get that.

We originally had a regression related to some reorganization of the
nixpkgs lib test suite in which there was broken parameter passing.
This, too, we got quickfixed in nixpkgs, so we don't need any changes
for it: https://github.com/NixOS/nixpkgs/pull/317772

Related: https://gerrit.lix.systems/c/lix/+/1428
Fixes: lix-project/lix#385

Change-Id: I26d41ea826fec900ebcad0f82a727feb6bcd28f3
2024-06-12 15:34:22 -07:00
jade 8a3d063a49 Merge changes from topic "releng" into main
* changes:
  releng: add prod environment, ready for release
  releng: automatically figure out if we should tag latest for docker
  releng: support multiarch docker images
  manual: rewrite the docker guide now that we have images
  Rewrite docker to be sensible and smaller
  Implement docker upload in the releng tools
2024-06-11 04:45:12 +00:00
jade a986a8dfa1 Merge "Revert "flake: update nixpkgs pin 23.11->24.05 (+ boehmgc compat changes)"" into main 2024-06-10 04:48:12 +00:00
jade 8a09465c3a Revert "flake: update nixpkgs pin 23.11->24.05 (+ boehmgc compat changes)"
This reverts commit 28a079f841.

Reason for revert: This caused a pile of regressions in CI, and does not pass nix flake check. Some number of them are fixed in CL: https://gerrit.lix.systems/c/lix/+/1429 but there's more to be fixed.

We should defer this after 2.90.

Change-Id: Ib839d0fcb08eb52094af2b521145e3c1b4e0556f
2024-06-10 04:29:13 +00:00
jade 9aeb314e6a releng: support multiarch docker images
If we don't want to have separate registry tags by architecture (EWWWW),
we need to be able to build multiarch docker images. This is pretty
simple, and just requires making a manifest pointing to each of the
component images.

I was *going* to just do this API prodding with manifest-tool, but it
doesn't support putting metadata on the outer manifest, which is
actually kind of a problem because it then doesn't render the metadata
on github. So I guess we get a simple little containers API
implementation that is 90% auth code.

Change-Id: I8bdd118d4cbc13b23224f2fb174b232432686bea
2024-06-09 20:33:24 -07:00
jade 7dfa2a761e Merge changes from topic "releng" into main
* changes:
  releng: support pushing the manual to docs also
  Expose officialRelease from the flake
  Put into place initial release engineering
2024-06-09 08:28:52 +00:00
jade ff95b980d4 Implement docker upload in the releng tools
This uses skopeo to not think about docker daemons. I, however, noticed
that the docker image we had would have totally terrible cache hits, so
I rewrote it.

Fixes: lix-project/lix#252

Change-Id: I3c5b6c1f3ba0b9dfcac212b2148f390e0cd542b7
2024-06-09 00:30:12 -07:00
Pierre Bourdon 28a079f841
flake: update nixpkgs pin 23.11->24.05 (+ boehmgc compat changes)
The boehmgc changes are bundled into this commit because doing otherwise
would require an annoying dance of "adding compatibility for < 8.2.6 and
>= 8.2.6" then updating the pin then removing the (now unneeded)
compatibility. It doesn't seem worth the trouble to me given the low
complexity of said changes.

Rebased coroutine-sp-fallback.diff patch taken from https://github.com/NixOS/nixpkgs/pull/317227

Change-Id: I8c590e9fe25c0f566d0cfeacb96d8cf50abf12e8
2024-06-09 01:25:53 +02:00
jade 4f94531209 Merge changes from topic "releng" into main
* changes:
  Add meson release note
  Move version to a JSON file so we can have release names
  Remove rl-next-dev
2024-06-07 03:53:31 +00:00
jade bdf1b264ad Expose officialRelease from the flake
Change-Id: If87beb3f31dfb5d59862294ac2e1c821ea864277
2024-06-06 20:53:08 -07:00
Qyriad ec768df004 Merge changes Ic4be41eb,I48db2385 into main
* changes:
  devshells: only enable pch for clang
  build: expose option to enable or disable precompiled std headers
2024-06-06 22:21:52 +00:00
jade 9c77c62e73 Move version to a JSON file so we can have release names
Change-Id: I5ff3396a302565ee5ee6c2db97e048e403779076
2024-06-06 15:08:12 -07:00
jade 1659404626 Add xonsh to the shell
Change-Id: If8f3825d2bdcc3f1d00583a11d890c1c8ab37b9f
2024-06-06 14:50:27 -07:00
jade e0748377dc pname: nix -> lix
This had a regression last time: https://gerrit.lix.systems/c/lix/+/1196

But f3f68fcfa fixed upgrade-nix to not be broken, so this should be ok tbh.

Change-Id: I48ea1359790878bb8ead5d8a4b3f61caa4aabfb5
2024-06-06 20:42:29 +00:00
Qyriad 766e718f67 devshells: only enable pch for clang
clangd seems to break if GCC is using precompiled headers for C++'s
standard library, so this sets -Denable-pch-std=${stdenv.cc.isClang}

Fixes #374.

Change-Id: Ic4be41ebe7576ebcb9c208275596f953c2003109
2024-06-06 12:48:13 -06:00
jade 0f99ed43f1 build-time: remove 20% more by PCH'ing C++ stdlib
It seems like someone implemented precompiled headers a long time ago
and then it never got ported to meson or maybe didn't work at all.

This is, however, blessedly easy to simply implement. I went looking for
`#define` that could affect the result of precompiling the headers, and
as far as I can tell we aren't doing any of that, so this should truly
just be free build time savings.

Previous state:
Compilation (551 times):
  Parsing (frontend):         1302.1 s
  Codegen & opts (backend):    956.3 s

New state:
**** Time summary:
Compilation (567 times):
  Parsing (frontend):         1123.0 s
  Codegen & opts (backend):   1078.1 s

I wonder if the "regression" in codegen time is just doing the PCH
operation a few times, because meson does it per-target.

Change-Id: I664366b8069bab4851308b3a7571bea97ac64022
2024-05-30 21:54:21 +00:00
jade e6e5cacabe shellHook: make it actually run
When we changed this in I91cb6eb6668f3a8eace36ecbdb01eb367861d77b to
not run in nested shells, we didn't predict that `nix develop` would do
something ridiculous and append -env to things silently. `nix-shell` of
course does not do this, so we need to tolerate both.

Change-Id: Ibe7cf546823d7358ebc0414ecbe154e3e3194f45
2024-05-30 21:54:21 +00:00
Qyriad 6475793678 build: fix static aws-cpp-sdk
Change-Id: I310830951106f194f6960a6b2d52b5081a7f6156
2024-05-30 00:40:25 -06:00
Qyriad 2760818f06 package: fix derivation correctness when static
Change-Id: I394bb72d9f378cd78acc6cf67a9bb15e342d57c4
2024-05-30 04:21:57 +00:00
Qyriad eac3546d50 package: return from shellHook correctly
If our shellHook is being run from a nested nix-shell (see 7a12bc200¹),
then (I think) it is run from a bash function due to the nesting, then
`return` is correct. If its `eval`'d though, then there isn't really a
correct way to early exit. So we can just unconditionally be executed in
a function.

Basically, we have IIFE at home.

[1]: 7a12bc2007

Change-Id: Iacad25cbbf66cde2911604e6061e56ad6212af7e
2024-05-30 04:21:57 +00:00
Qyriad 68937f2b64 package: dequalify {host,build}Platform for convenience
Change-Id: I5ffeac894a5bff101683cf3d566c63b478779962
2024-05-30 04:21:47 +00:00
terru - 7a12bc2007 package: don't run shellHook in nested nix-shells
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
2024-05-27 22:09:57 +02:00
Qyriad 65da3e7199 make CTRL+Z work in the REPL
Editline just wasn't being built with --enable-sigstop lol

Change-Id: I35a78f74ea100d97f26b2b41990deb373fd9cd9a
2024-05-24 03:10:12 +00:00
Pierre Bourdon 6922d67eb3 package.nix: add meta.mainProgram
nix-repl> lib.getExe (builtins.getFlake ".").packages.x86_64-linux.nix
"/nix/store/ajps2zn5hlap0l2abvnfdaphg8k0789r-lix-2.90.0pre20240524_dirty/bin/nix"

Fixes #316.

Change-Id: Iec3125dc2dc99d100beb6357f7d1555456924ddc
2024-05-24 02:15:45 +00:00
jade d1fa446454 [emergency revert]: make pname nix once more
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
2024-05-24 01:33:42 +00:00
jade c97e17144e packaging: rename nixexpr -> lixexpr and so on
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
2024-05-23 16:45:23 -06:00
julia 7a3745b076
Deprecate the online flake registries and vendor the default registry
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
2024-05-18 12:27:23 +10:00
Qyriad 236466faf3 package: add --print-errorlogs to meson's tests
This should have been in there originally, which is our mistake,
considering that debugging CI failures is basically impossible without
it.

Change-Id: I4ab8799e6e0abca1984ed9801fe10c58200861a3
2024-05-17 21:42:33 +00:00
jade e1119f4378 make lix dev shells un-bear-able since we un-make them now
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
2024-05-16 23:43:44 -07:00
jade 7cfaf057e3 release-notes: build unreleased release notes by default
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
2024-05-15 15:01:38 -07:00
Maximilian Bosch a4c943403f
flake: update nixpkgs input to latest nixos-23.11
This includes the update to libseccomp 2.5.5[1], so we don't need to
override it on our own.

[1] https://nixpk.gs/pr-tracker.html?pr=306070

Change-Id: I1fa9c7fcc23e501d75f774745107c6bb086ced70
2024-05-08 23:03:28 +02:00
Qyriad f782c8a60a flake: refactor devShell creation
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
2024-05-07 18:09:51 -06:00
Qyriad 8822fd7dd5 package: default the build-release-notes arg like we do with lix-doc
Change-Id: I0e2df55efc1cd6ea0a3252b9f26676e84612fdb6
2024-05-07 17:07:53 -06:00
Qyriad b9be46fb31 remove the autoconf+Make buildsystem
We're not using it anymore. Any leftover bugs in the Meson buildsystem
are now just bugs.

Closes #249.

Change-Id: I0465a0c37ae819f94d40e7829f5bff046aa63d73
2024-05-07 17:04:30 -06:00
Nikodem Rabuliński e8a603fb2f Merge changes Icf26010a,Ib6161567 into main
* changes:
  Always initialize curl in parent process on darwin
  Fix failing darwin tests
2024-05-07 21:26:24 +00:00
Nikodem Rabuliński f894cce79b
Always initialize curl in parent process on darwin
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
2024-05-07 20:43:17 +02:00
jade bf1a22aa8e Remove README.md from build dependencies
Now we will simply hit cache every time anyone changes readme, yay!

Change-Id: I5906f589d319ff6d43cbd2b467887e08f7474283
2024-05-06 18:23:57 -07:00
Maximilian Bosch 3580a4b7bf package: remove assert for libseccomp version
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
2024-05-04 11:25:29 +02:00
Maximilian Bosch 045ee37438 libstore/local-derivation-goal: prohibit creating setuid/setgid binaries
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
2024-05-03 16:29:06 +02:00