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
just accumulate error data into result.data as we would for successful
transfers without a dataCallback. errorSink and data would contain the
same data in error cases anyway, so splitting them is not very useful.
Change-Id: I00e449866454389ac6a564ab411c903fd357dabf
This creates new subclasses of LocalStore for each OS to include
platform-specific functionality. Currently this just includes garbage
collector roots but it could be extended to sandboxing as well.
In order to make sure that the generic LocalStore is not accidentally
constructed, its constructor is protected. A Fallback is provided which
implements no functionality except constructors.
Change-Id: I836a28e90b68309873f75afb83e0f1b2e2c89fb3
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
don't reimplement header parsing. this was only really needed due to the
ancient github bug we no longer care about, everything else we have done
in custom code can also be done using curl itself. doing this also fixes
possible sources of header smuggling (because the header function didn't
unfold headers and we'd trim them before parsing, which would've made us
read contents of one header as a fully formed header in itself). this is
a slight behavior change because we now honor only the first instance of
a given header where previous behavior was to honor either the last or a
combination of all of them (accept-ranges was logical-or'd by accident).
Change-Id: I93cb93ddb91ab98c8991f846014926f6ef039fdb
this was a workaround for a *github* bug that happend *in 2015*.
not only is github no longer buggy, it shouldn't have been nix's
responsibility to work around these bugs like this to begin with
while we're at it we'll also remove another workaround—again for
github specifically and again for etag handling—from 2021 that's
also not needed any more. future workarounds for serverside bugs
should probably come with an expiration date that mutates into a
build warning after a while, otherwise this *will* happen again.
Change-Id: I74f739ae3e36d40350f78bebcb5869aa8cc9adcd
the previous solution to the wakeup problem (adding a pipe and passing
it as an additional fd to curl_multi_wait) worked, but there have been
builtin alternatives for this since 2020. not only do these save code,
they're also a lot more likely to work natively on windows when needed
Change-Id: Iab751b900997110a8d15de45ea3ab0c42f7e5973
the oldest version checked for here is 7.47, which was released in
2016. it's probably safe to say that we do not need these any more
Change-Id: I003411f6b2ce6d56f7ca337390df3ea86bd59a99
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
(cherry picked from commit 0774e8ba33c060f56bad3ff696796028249e915a)
Change-Id: I00920fb33077b831a1bb4a1b68d515ba8c3c2a69
The statically embedded busybox is not required for Lix to work, but
package.nix explicitly sets this, which was accidentally being ignored.
Change-Id: Ieeff830ac7d1f5fabe84d1a6cfd82f13d79035bf
Either the contents of `line` could cause format errors, or this usage
is Technically safe. However, I trust nothing, especially with
boost::format.
Change-Id: I07933b20bde3b305a6e5d61c2a7bab6ecb042ad9
Previously if isStorePath() was called on anything other than a
top-level /nix/store/some-path, it would throw a BadStorePath exception.
This commit duplicates the absolutely trivial check, into
maybeParseStorePath(), and leaves exception throwing to
parseStorePath(), the function that assumes you're already giving a
valid path instead of the one whose purpose is to check if its valid or
not...
Change-Id: I8dda548f0f88d14ca8c3ee927d64e0ec0681fc7b
Saves us a bunch of thinking about how to handle symlinks, and prevents
the DNS config from changing on the fly under the build, which may or may
not be a good thing?
Change-Id: I071e6ae7e220884690b788d94f480866f428db71
this should be a link, not an anchor. it should also point to the
`gloss-store` element, not the `#gloss-store` element.
Change-Id: I1f2803093179549637e10f917ad73399a419131b
Instead of $sysconfdir.
Fixes#231, but there's more to do in following commits to make
Meson-built Lix actually look in /etc/nix.
Change-Id: Ia8d627070f405843add46e05cff5134b76b8eb48
This reverts commit 491caad6f62c21ffbcdebe662e63ec0f72e6f3a2.
this is not actually legal for nix! throwing exceptions in destructors
is fine, but the way nix is set up we'll end up throwing the exception
we received from the remote *twice* in some cases, and such cases will
cause an immediate terminate without active exception.
Change-Id: I74c46b9f26fd791086e4193ec60eb1deb9a5bb2a
setting this only on exceptions caused by actual fd access is not
sufficient to diagnose all errors (such as SerialisationError) in
some cases. this usually does not have any negative effects since
those errors will end up killing the process in another way. this
is not a reliable assumption though and we should be using proper
error handling (and closing connections more often, preferring to
close over keeping something open that might be in a weird state)
Change-Id: I1b792cd7ad8ba9ff0f6bd174945ab2575ff2208e
the duplication of exception handling was added without justification,
so we can only assume that it was done like this because Finally could
not throw exceptions safely. since this has now been rectified we will
deduplicate this handler code again.
Change-Id: I40721f3378c0fd9f34e2914a16d383f6e2713b40
usage of this flag previously kept connections open much longer than
necessary, and at the same time obscured that a connection was being
dropped when it *was* set. new variable names clarify this somewhat.
Change-Id: I11f6f08f37a5e4dc04ea6c6036ea589154b121c6
it was used incorrectly (not swapped on handle move), only used in one
place (that is now handled with exception handling detection in Handle
itself), and if ever reintroduced should be replaced with a different,
more understandable mechanism (like an explicit dropAsInvalid method).
Change-Id: Ie3e5d5cfa81d335429cb2ee5c3ad85c74a9df17b
this was never actually used, and bad design in the first place—why
should a bad resource be put back into the idle pool? just drop it.
Change-Id: Idab8774bee19dadae0209d404c4fb86dd4aeba1e
The big ones here are `trim-trailing-whitespace` and `end-of-file-fixer`
(which makes sure that every file ends with exactly one newline
character).
Change-Id: Idca73b640883188f068f9903e013cf0d82aa1123
This does involve making a large number of destructors able to throw,
because we had to change it high in the class hierarchy. Oh well.
Change-Id: Ib62d3d6895b755f20322bb8acc9bf43daf0174b2
* some things that can throw are marked noexcept
yet the linter seems to think not. Maybe they can't throw in practice.
I would rather not have the UB possibility in pretty obvious cold
paths.
* various default-case-missing complaints
* a fair pile of casts from integer to character, which are in fact
deliberate.
* an instance of <https://clang.llvm.org/extra/clang-tidy/checks/bugprone/move-forwarding-reference.html>
* bugprone-not-null-terminated-result on handing a string to curl in
chunks of bytes. our usage is fine.
* reassigning a unique_ptr by CRIMES instead of using release(), then
using release() and ignoring the result. wild. let's use release() for
its intended purpose.
Change-Id: Ic3e7affef12383576213a8a7c8145c27e662513d
the autoconf build system defaults to /nix/var, not /nix/var/nix. the
latter is only used in libstore, so we'll move the extra segment there.
Change-Id: Idfbc988ee302355982abdcd51d6d7b5d5d661c0d
Without this, the Meson setup won't bail out if nlohmann_json is
missing, leading to subpar DX (and maybe worse, but I'm not entirely
sure).
Change-Id: I5913111060226b540dcf003257c99a08e84da0de
one headers (args/root.hh) was simply missing, and the generated headers
were not installed. not all of them *should* be installed either, only a
select few (and sadly this needs a custom target for each one, it seems)
Change-Id: I37b25517895d0e5e521abc1202fa65624de57ed1
This was achieved by running maintainers/buildtime_report.sh on the
build directory of a meson build, then asking "why the heck is json
eating our build times", and strategically moving the json using bits
out of widely included headers.
It turns out that putting literally any metrics whatsoever into the
build had immediate and predictable results.
Results are 1382.5s frontend time -> 1175.4s frontend time, back end
time approximately invariant.
Related: #159
Change-Id: I7edea95c8536203325c8bb4dae5f32d727a21b2d
Once this commit lands, we are even more visible in analytics FWIW.
Change-Id: Id7e0c162315d0f191edbea9cb5fb82ce363704b9
Signed-off-by: Raito Bezarius <raito@lix.systems>
protocol versions are sent as u64. on the peer we read them as uint64,
check that the upper half is 0, and throw an exception if not. we then
read an arbitrary amount of data from the peer and dump it to the user
terminal. this is a little bit ridiculous, can never happen in correct
implementation, and is severly untested. let us just drop it entirely.
Change-Id: Ibd2f53a765341ed6439d40d9d1eac11e79c6b5e3
If the state SQLite database is configured to use a write-ahead-log, it
creates WAL files in the state directory.
When the state SQLite database is closed by the `nix-daemon` after
builds, those files are removed.
When an unprivileged user would like to open _in read only_ that
database, they cannot do so because they would need to create those WAL
files and they do not have the permission to do so.
For this, SQLite offers a "persistent WAL" feature [1] to leave the WAL
files around, even after closing the database.
This CL enable the persistent WAL mode.
Fixes: https://github.com/NixOS/nix/issues/10300
[1]: https://www.sqlite.org/wal.html
Change-Id: Id8ae534d7d2290457af28782e5215222ae051fe5
Signed-off-by: Raito Bezarius <raito@lix.systems>
Maximilian Bosch
eldritch horrors
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Qyriad
Alyssa Ross
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jade
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