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
In f047e4357b, I missed the behavior that if
building without a dedicated build user (i.e. in single-user setups), seccomp
setup failures are silently ignored. This was introduced without explanation 7
years ago (ff6becafa8). Hopefully the only
use-case nowadays is causing spurious test suite successes when messing up the
seccomp filter during development. Let's try removing it.
Change-Id: Ibe51416d9c7a6dd635c2282990224861adf1ceab
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
According to doc/manual/src/contributing/hacking.md, all development
shells should also be available in classic nix using the -A argument
to nix-shell, e.g.
nix-shell -A native-clangStdenvPackages
This was not actually the case; flake-compat generates attrsets like
nix-shell -A devShells.x86_64-linux.native-clangStdenvPackages
instead. These are unwieldy to use, so rather than changing the docs,
this changes the shell.nix file to result in the documented behavior.
Change-Id: I0920ccbdfddacf371f0aeaae7e290db65cf76ee7
check goals for timeouts first, and their activity fds only if no
timeout has occurred. checking for timeouts *after* activity sets
us up for assertion failures by running multiple build completion
notifiers, the first of which will kill/reap the the goal process
and consuming the Pid instance. when the second notifier attempts
to do the same it will core dump with an assertion failure in Pid
and take down not only the single goal, but the entire daemon and
all goals it was building. luckily this is rare in practice since
it requires a build to both finish and time out at the same time.
writing a test for this is not feasible due to how much it relies
on scheduling to actually trigger the underlying bug, but on idle
machines it can usually be triggered by running multiple sleeping
builds with timeout set to the sleep duration and `--keep-going`:
nix-build --timeout 10 --builders '' --keep-going -E '
with import <nixpkgs> {};
builtins.genList
(i: runCommand "foo-${toString i}" {} "sleep 10")
100
'
Change-Id: I394d36b2e5ffb909cf8a19977d569bbdb71cb67b
8c06b7b43¹ made libfetchers log the URL being fetched just before the
actual fetch, particularly in case something freezes. This used the base
URL, to not include query parameters, as the Nixpkgs lib tests assume
that stderr logs will be equal across shallow and non-shallow git
fetches (and shallow fetches have the ?shallow=1 query parameter).
8c06b7b43 assumed that the `base` field of ParsedURL would be populated,
as the comment simply says "URL without query/fragment"... but
apparently it is not populated when the URL being fetched is *already*
fetched, which caused libfetchers to log things like
fetching gitlab input ''
which is. silly. but you know, busted lix be busted.
Anyway, with this commit we just remove the query params before printing
instead, which seems to do the right thing
[1]: 8c06b7b431
Change-Id: I9b9988992029aa6abef786f20b66e68c2ebb97d4
The `builder` local variable and duplicate `args.push_back` are no
longer required since the Darwin sandbox stopped using `sandbox-exec`.
The `drv->isBuiltin` check is not required either, as args are not
accessed when the builder is builtin.
Change-Id: I80b939bbd6f727b01793809921810ff09b579d54
Seccomp filtering and the no-new-privileges functionality improve the security
of the sandbox, and have been enabled by default for a long time. In
lix-project/lix#265 it was decided that they
should be enabled unconditionally. Accordingly, remove the allow-new-privileges
(which had weird behavior anyway) and filter-syscall settings, and force the
security features on. Syscall filtering can still be enabled at build time to
support building on architectures libseccomp doesn't support.
Change-Id: Iedbfa18d720ae557dee07a24f69b2520f30119cb
`meson test` refuses to let `--verbose` (which shows the entire
invocation and stdio) override `--quiet`, but if neither are specified
in the justfile then you can use either `just test -q` or `just test -v`
Change-Id: I449e13084ce64666b7ee2ab4280818782fb8185a
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
* changes:
docs: linkify nix3-build mention in nix-build.md
build: make internal-api-docs PHONY
cleanup lookupFileArg
add docstring to lookupFileArg
add libcmd test for lookupFileArg
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
Since we're skipping Meson's dependency tracking, for the
internal-api-docs custom target, we should just consider it a phony
target and build it on every request.
Change-Id: I3b0bcea30ee9a4830023ccc5bededf995e96cccc
this should make it easier to spot future instances of entries being
duplicated by accident. also add a pre-commit check to remain sorted
Change-Id: I500caf862e93480b38c9d51144273bb2dcab1af0
File not found while importing causes a SysError, not an EvalError,
which is not currently caught by the tab-completion handler. Ignoring
all SysErrors might seem "dangerous" but this is the tab-completion
handler, any exception being bubbled up from there causes unexpected
behavior (causes the whole repl to exit).
Fixes#340.
Change-Id: I643048a47935e77f582decc539d9e51bdb96c890
nixpkgs has 23000 attributes, and our previous limit would be hit if you
have more than one nixpkgs in the environment, for example, because
`repl-overlays` will load the new stuff from the environment on top of
the existing environment.
This is not really testable since if we did write such a test, it would
just be testing this constant tbh...
Fixes: lix-project/lix#337
Change-Id: I49197bfb4db55b082f914f0d70e84f5f5f110954