Unfortunately, io_uring is totally opaque to seccomp, and while currently there
are no dangerous operations implemented, there is no guarantee that it remains
this way. This means that io_uring should be blocked entirely to ensure that
the sandbox is future-proof. This has not been observed to cause issues in
practice.
Change-Id: I45d3895f95abe1bc103a63969f444c334dbbf50d
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. To the contrary, it has been measured that the the
actual filter constructed here has approximately the same overhead as a very
simple filter blocking only one system call.
This commit tries to keep the behavior as close to unchanged as possible. The
system call list is in line with libseccomp 2.5.5 and glibc 2.39, which are the
latest versions at the point of writing. Since libseccomp 2.5.5 is already a
requirement and the distributions shipping this together with older versions of
glibc are mostly not a thing any more, this should not lead to more build
failures any more.
[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
getSelfExe is used in a few places re-execute nix.
Current code in this file uses ifdefs to support several
platforms, just keep doing that
Change-Id: Iecc2ada0101aea0c30524e3a1218594f919d74bf
This was done originally because std::smatch does not accept `const char
*` as iterators. However, this was because we should have been using
std::cmatch instead.
Change-Id: Ibe73851fd39755e883df2d33d22fed72ac0a04ae
Nobody has stepped up to add further support for Hurd since this code
appeared in 2010 or 2014. We don't need it.
Change-Id: I400b2031a225551ea3c71a3ef3ea9fdb599dfba3
Use libprocstat to find garbage collector roots on FreeBSD.
Tested working on a FreeBSD machine, although there is no CI yet
Change-Id: Id36bac8c3de6cc4de94e2d76e9663dd4b76068a9
Error is pretty large, and most goals do not fail. this alone more than
halves the size of Goal on x86_64-linux, from 720 bytes down to 344. in
derived classes the difference is not as dramatic, but even the largest
derived class (`LocalDerivationGoal`) loses almost 20% of its footprint
Change-Id: Ifda8f94c81b6566eeb3e52d55d9796ec40c7bce8
the goals are either already using std::async and merely forgot to
remove std::thread vestiges or they emulate async with threads and
promises. we can simply use async directly everywhere for clarity.
Change-Id: I3f05098310a25984f10fff1e68c573329002b500
under owner_less it's equivalent to insert(), only sometimes a little
bit faster because it does not construct a weak_ptr if the goal is in
the set already. this small difference in performance does not matter
here and c++23 will make insert transparent anyway, so we can drop it
Change-Id: I7cbd7d6e0daa95d67145ec58183162f6c4743b15
*accidentally* overriding a function is almost guaranteed to be an
error. overriding a function without labeling it as such is merely
bad style, but bad style that makes the code harder to understand.
Change-Id: Ic0594f3d1604ab6b3c1a75cb5facc246effe45f0
Commit 0109368c3f missed to include a required
header, which is not noticed when the precompiled header is enabled because
it's included in that. Also include it in the file so that the build without
precompiled header works too.
Change-Id: Id7a7979684b64f937f7f8191612952d73c113015
Due to a leftover from a previous version where the buffer was allocated on the
stack, the change introduced in commit 4ec87742a1
accidentally passes the size of a pointer as the size of the buffer to the
decompressor. Since the former is much smaller (usually 8 bytes instead of 64
kilobytes), this is safe, but leads to considerable overhead; most notably, due
to excessive progress reports, which happen for each chunk. Pass the proper
buffer size instead.
Change-Id: If4bf472d33e21587acb5235a2d99e3cb10914633
This commit adds a new helper template function to gc-alloc.hh (which is
probably where you want to look at first, O great reviewer [custom file
ordering in review diffs when]), which uses a type argument to determine
the size to allocate, rather than making the caller use sizeof().
Change-Id: Ib5d138d91a28bdda304a80db24ea9fb08669ad22
The purpose of this function has little to do with immutability. Value's
strings are never mutated, and the point of this function is to
singleton empty strings.
Change-Id: Ifd41dd952409d54e4d3de9ab59064e6928b0e480
SimpleLogger is not fully thread-safe, and all loggers that wrap it are
also not safe accordingly. this does not affect much, but in rare cases
it can cause interleaving of messages on stderr when used with the json
or raw log formats. the fix applied here is a bit of a hack, but fixing
this properly requires rearchitecting the logger infrastructure. nested
loggers are not the most natural abstraction here, and it is biting us.
Change-Id: Ifbf34fe1e85c60e73b59faee50e7411c7b5e7c12
it's only used once, and even that one use is highly questionable. more
instances of warnOnce should be much more principled than this has been
Change-Id: I5856570c99cb44462e700d753d0c706a5db03c4b
If useChroot = false, and user namespaces aren't available for some
reason (e.g. within a Docker container), this fixes a pointless warning
being emitted, as we would never attempt to use them even if they were
available.
Change-Id: Ibcee91c088edd2cd19e70218d5a5802bff8f537b
This removes a *whole load* of variables from scope and enforces thread
boundaries with the type system.
There is not much change of significance in here, so the things to watch
out for while reviewing it are primarily that the destructor ordering
may have changed inadvertently, I think.
Change-Id: I3cd87e6d5a08dfcf368637407251db22a8906316
* changes:
Fixup a bunch of references to nixos.org manuals
Add release notes for removing overflow from Nix language
expr: fix a compiler warning about different signs in comparison
* changes:
doc/release-notes: add for pretty printing improvements
libexpr/print: do not show elided nested items when there are none
libexpr/print: never show empty attrsets or derivations as «repeated»
libexpr/print: pretty-print idempotently
* changes:
docs: document the actual comparison rules instead of lies
daemon: remove workaround for macOS kernel bug that seems fixed
daemon: fix a crash bug "FATAL: exception not rethrown"
When the configured maximum depth has been reached, attribute sets and lists
are printed with ellipsis to indicate the elision of nested items. Previously,
this happened even in case the structure being printed is empty, so that such
items do not in fact exist. This is confusing, so stop doing it.
Change-Id: I0016970dad3e42625e085dc896e6f476b21226c9
The repeated value detection logic exists so that the occurrence of large
common substructures does not fill up the screen or the computer's memory.
However, empty attribute sets and derivations (when their detection is enabled)
are always cheap to print, and in practice I have observed them to make up a
significant majority of the cases where I was annoyed by the repeated value
detection kicking in. Furthermore, `nix-instantiate --eval` already disables
this logic for empty attribute sets, and empty lists are already exempted
everywhere. For these reasons, always print empty attribute sets and
derivations as what they are.
Change-Id: I5dac8e7739f9d726b76fd0521ec46f38af94463f
When pretty-printing is enabled, previously an unforced thunk would trigger
indentation, even when it subsequently does not evaluate to a nested structure.
The resulting output looked inconsistent, and furthermore pretty-printing was
not idempotent (since pretty-printing the same value again, which is now fully
evaluated, will not trigger indentation).
When strict evaluation is enabled, force the item before inspecting its type,
so that it is properly known whether it contains a nested structure.
Furthermore, there is no need to cause indentation for unforced thunks, since
the very next operation will be printing them as `«thunk»`.
This is mostly a port of https://github.com/NixOS/nix/pull/11100 , but we only
force the item when it's going to be forced anyway due to strict
pretty-printing, and a new test was written since the REPL testing framework in
Lix is different.
Co-Authored-By: Robert Hensing <robert@roberthensing.nl>
Change-Id: Ib7560fe531d09e05ca6b2037a523fe21a26d9d58
The insertion marker comment broke the list into two parts, the first
containing only the link to the upcoming release notes and the second the
past releases. This confused the generator, leading to the first part being
discarded. Indent the marker comment so that it's syntactically part of the
preceding item, and in particular doesn't split the list any more.
Change-Id: I357c51bb03e4e0d79a76d30158615fd9eda95ea8
