For the hardened profile disable symmetric multi threading. There seems to be
no *proven* method of exploiting cache sharing between threads on the same CPU
core, so this may be considered quite paranoid, considering the perf cost.
SMT can be controlled at runtime, however. This is in keeping with OpenBSD
defaults.
TODO: since SMT is left to be controlled at runtime, changing the option
definition should take effect on system activation. Write to
/sys/devices/system/cpu/smt/control
For the hardened profile enable flushing whenever the hypervisor enters the
guest, but otherwise leave at kernel default (conditional flushing as of
writing).
Introduces the option security.protectKernelImage that is intended to control
various mitigations to protect the integrity of the running kernel
image (i.e., prevent replacing it without rebooting).
This makes sense as a dedicated module as it is otherwise somewhat difficult
to override for hardened profile users who want e.g., hibernation to work.
The OS Login package enables the following components:
AuthorizedKeysCommand to query valid SSH keys from the user's OS Login
profile during ssh authentication phase.
NSS Module to provide user and group information
PAM Module for the sshd service, providing authorization and
authentication support, allowing the system to use data stored in
Google Cloud IAM permissions to control both, the ability to log into
an instance, and to perform operations as root (sudo).
Having pam_unix set to "sufficient" means early-succeeding account
management group, as soon as pam_unix.so is succeeding.
This is not sufficient. For example, nixos modules might install nss
modules for user lookup, so pam_unix.so succeeds, and we end the stack
successfully, even though other pam account modules might want to do
more extensive checks.
Other distros seem to set pam_unix.so to 'required', so if there are
other pam modules in that management group, they get a chance to do some
validation too.
For SSSD, @PsyanticY already added a workaround knob in
https://github.com/NixOS/nixpkgs/pull/31969, while stating this should
be the default anyway.
I did some thinking in what could break - after this commit, we require
pam_unix to succeed, means we require `getent passwd $username` to
return something.
This is the case for all local users due to the passwd nss module, and
also the case for all modules installing their nss module to
nsswitch.conf - true for ldap (if not explicitly disabled) and sssd.
I'm not so sure about krb5, cc @eqyiel for opinions. Is there some nss
module loaded? Should the pam account module be placed before pam_unix?
We don't drop the `security.pam.services.<name?>.sssdStrictAccess`
option, as it's also used some lines below to tweak error behaviour
inside the pam sssd module itself (by changing it's 'control' field).
This is also required to get admin login for Google OS Login working
(#51566), as their pam_oslogin_admin accounts module takes care of sudo
configuration.
A module for security options that are too small to warrant their own module.
The impetus for adding this module is to make it more convenient to override
the behavior of the hardened profile wrt user namespaces.
Without a dedicated option for user namespaces, the user needs to
1) know which sysctl knob controls userns
2) know how large a value the sysctl knob needs to allow e.g.,
Nix sandbox builds to work
In the future, other mitigations currently enabled by the hardened profile may
be promoted to options in this module.
I think pam_lastlog is the only thing that writes to these files in
practice on a modern Linux system, so in a configuration that doesn't
use that module, we don't need to create these files.
I used tmpfiles.d instead of activation snippets to create the logs.
It's good enough for upstream and other distros; it's probably good
enough for us.
The order of sudoers entries is significant. The man page for sudoers(5)
notes:
Where there are multiple matches, the last match is used (which is not
necessarily the most specific match).
This module adds a rule for group "wheel" matching all commands. If you
wanted to add a more specific rule allowing members of the "wheel" group
to run command `foo` without a password, you'd need to use mkAfter to
ensure your rule comes after the more general rule.
extraRules = lib.mkAfter [
{
groups = [ "wheel" ];
commands = [
{
command = "${pkgs.foo}/bin/foo";
options = [ "NOPASSWD" "SETENV" ];
}
]
}
];
Otherwise, when configuration options are merged, if the general rule
ends up after the specific rule, it will dictate the behavior even when
running the `foo` command.
This introduces an option that allows us to turn off stateful generation
of Diffie-Hellman parameters, which in some way is still "stateful" as
the generated DH params file is non-deterministic.
However what we can avoid with this is to have an increased surface for
failures during system startup, because generation of the parameters is
done during build-time.
Aside from adding a NixOS VM test it also restructures the type of the
security.dhparams.params option, so that it's a submodule.
A new defaultBitSize option is also there to allow users to set a
system-wide default.
I added a release notes entry that described what has changed and also
included a few notes for module developers using this module, as the
first usage already popped up in NixOS/nixpkgs#39507.
Thanks to @Ekleog and @abbradar for reviewing.
This allows to set the default bit size for all the Diffie-Hellman
parameters defined in security.dhparams.params and it's particularly
useful so that we can set it to a very low value in tests (so it doesn't
take ages to generate).
Regardless for the use in testing, this also has an impact in production
systems if the owner wants to set all of them to a different size than
2048, they don't need to set it individually for every params that are
set.
I've added a subtest to the "dhparams" NixOS test to ensure this is
working properly.
Signed-off-by: aszlig <aszlig@nix.build>
@Ekleog writes in https://github.com/NixOS/nixpkgs/pull/39526:
> I think a default of 4096 is maybe too much? See certbot/certbot#4973;
> Let's Encrypt supposedly know what they are doing and use a
> pre-generated 2048-bit DH params (and using the same DH params as
> others is quite bad, even compared to lower bit size, if I correctly
> remember the attacks available -- because it increases by as much the
> value of breaking the group).
> Basically I don't have anything personal against 4096, but fear it may
> re-start the arms race: people like having "more security" than their
> distributions, and having NixOS already having more security than is
> actually useful (I personally don't know whether a real-size quantum
> computer will come before or after our being able to break 2048-bit
> keys, let alone 3072-bit ones -- see wikipedia for some numbers).
> So basically, I'd have set it to 3072 in order to both decrease build
> time and avoid having people setting it to 8192 and complaining about
> how slow things are, but that's just my opinion. :)
While he suggests is 3072 I'm using 2048 now, because it's the default
of "openssl dhparam". If users want to have a higher value, they can
still change it.
Signed-off-by: aszlig <aszlig@nix.build>
Previously the script would contain an empty `if` block (which is invalid
syntax) if both `data.activationDelay == null` and `data.postRun == ""`. Fix
this by adding a no-op `true`.
First of all let's start with a clean up the multiline string
indentation for descriptions, because having two indentation levels
after description is a waste of screen estate.
A quick survey in the form of the following also reveals that the
majority of multiline strings in nixpkgs is starting the two beginning
quotes in the same line:
$ find -name '*.nix' -exec sed -n -e '/=$/ { n; /'\'\''/p }' {} + | wc -l
817
$ find -name '*.nix' -exec grep "= *'' *\$" {} + | wc -l
14818
The next point is to get the type, default and example attributes on top
of the description because that's the way it's rendered in the manual.
Most services have their enable option close to the beginning of the
file, so let's move it to the top.
Also, I found the script attribute for dhparams-init.service a bit hard
to read as it was using string concatenation to split a "for" loop.
Now for the more substantial clean ups rather than just code style:
* Remove the "with lib;" at the beginning of the module, because it
makes it easier to do a quick check with "nix-instantiate --parse".
* Use ConditionPathExists instead of test -e for checking whether we
need to generate the dhparams file. This avoids spawning a shell if
the file exists already and it's probably more common that it will
exist, except for the initial creation of course.
* When cleaning up old dhparams file, use RemainAfterExit so that the
unit won't be triggered again whenever we stop and start a service
depending on it.
* Capitalize systemd unit descriptions to be more in par with most
other unit descriptions (also see 0c5e837b66).
* Use "=" instead of "==" for conditionals using []. It's just a very
small nitpick though and it will only fail for POSIX shells. Bash on
the other side accepts it anyway.
Signed-off-by: aszlig <aszlig@nix.build>
Cc: @Ekleog
This option allows us to turn off stateful generation of Diffie-Hellman
parameters, which in some way is still stateful as the generated DH
params file is non-deterministic.
However what we can avoid with this is to have an increased surface for
failures during system startup, because generation of the parameters is
done during build-time.
Another advantage of this is that we no longer need to take care of
cleaning up the files that are no longer used and in my humble opinion I
would have preferred that #11505 (which puts the dhparams in the Nix
store) would have been merged instead of #22634 (which we have now).
Luckily we can still change that and this change gives the user the
option to put the dhparams into the Nix store.
Beside of the more obvious advantages pointed out here, this also
effects test runtime if more services are starting to use this (for
example see #39507 and #39288), because generating DH params could take
a long time depending on the bit size which adds up to test runtime.
If we generate the DH params in a separate derivation, subsequent test
runs won't need to wait for DH params generation during bootup.
Of course, tests could still mock this by force-disabling the service
and adding a service or activation script that places pre-generated DH
params in /var/lib/dhparams but this would make tests less readable and
the workaround would have to be made for each test affected.
Note that the 'stateful' option is still true by default so that we are
backwards-compatible with existing systems.
Signed-off-by: aszlig <aszlig@nix.build>
Cc: @Ekleog, @abbradar, @fpletz
We're going to implement an option which allows us to turn off stateful
handling of Diffie-Hellman parameter files by putting them into the Nix
store.
However, modules now might need a way to reference these files, so we
add a now path option to every param specified, which carries a
read-only value of the path where to find the corresponding DH params
file.
I've also improved the description of security.dhparams.params a bit so
that it uses <warning/> and <note/>.
The NixOS VM test also reflects this change and checks whether the old
way to specify the bit size still works.
Signed-off-by: aszlig <aszlig@nix.build>
Cc: @Ekleog
This is needed because simp_le expects two certificates in fullchain.pem, leading to error:
> Not enough PEM encoded messages were found in fullchain.pem; at least 2 were expected, found 1.
We now create a CA and sign the key with it instead, providing correct fullchain.pem.
Also cleanup service a bit -- use PATH and a private temporary directory (which
is more suitable).
Kernel symlinks don't have st_size. Really thought I tested this, guess I ran the
wrong NixOS test :(
This reverts commit 6dab907ebe, reversing
changes made to eab479a5f0.
* bemenu: init at 2017-02-14
* velox: 2015-11-03 -> 2017-07-04
* orbment, velox: don't expose subprojects
the development of orbment and velox got stuck
their subprojects (bemenu, dmenu-wayland, st-wayland) don't work correctly outside of parent projects
so hide them to not confuse people
swc and wld libraries are unpopular and unlike wlc are not used by anything except velox
* pythonPackages.pydbus: init at 0.6.0
* way-cooler: 0.5.2 -> 0.6.2
* nixos/way-cooler: add module
* dconf module: use for wayland
non-invasive approach for #31293
see discussion at #32210
* sway: embed LD_LIBRARY_PATH for #32755
* way-cooler: switch from buildRustPackage to buildRustCrate #31150
Looking at upstream git repo (git://github.com/Yubico/pam-u2f.git) the
docs initially said the path was ~/.yubico/u2f_keys, but it was later
changed to ~/.config/Yubico/u2f_keys (in 2015).
I have run pam_u2f.so with "debug" option and observed that the correct
path indeed is ~/.config/Yubico/u2f_keys.
Currently, ecryptfs support is coupled to `security.pam.enableEcryptfs`, but one
might want to use ecryptfs without enabling the PAM functionality. This commit
splits it out into a `boot.supportedFilesystems` switch.
Ensure that modules required by all declared fileSystems are explicitly
loaded. A little ugly but fixes the deferred mount test.
See also https://github.com/NixOS/nixpkgs/issues/29019
This includes fuse-common (fusePackages.fuse_3.common) as recommended by
upstream. But while fuse(2) and fuse3 would normally depend on
fuse-common we can't do that in nixpkgs while fuse-common is just
another output from the fuse3 multiple-output derivation (i.e. this
would result in a circular dependency). To avoid building fuse3 twice I
decided it would be best to copy the shared files (i.e. the ones
provided by fuse(2) and fuse3) from fuse-common to fuse (version 2) and
avoid collision warnings by defining priorities. Now it should be
possible to install an arbitrary combination of "fuse", "fuse3", and
"fuse-common" without getting any collision warnings. The end result
should be the same and all changes should be backwards compatible
(assuming that mount.fuse from fuse3 is backwards compatible as stated
by upstream [0] - if not this might break some /etc/fstab definitions
but that should be very unlikely).
My tests with sshfs (version 2 and 3) didn't show any problems.
See #28409 for some additional information.
[0]: https://github.com/libfuse/libfuse/releases/tag/fuse-3.0.0
auditd creates an ordering cycle by adding wantedBy = [ "basic.target" ],
because of this the job job systemd-update-utmp.service/start is deleted.
Adding unitConfig.DefaultDependencies = false; to the auditd service unbreaks the cycle.
See also #11864
#11864 Support Linux audit subsystem
Add the auditd.service as NixOS module to be able to
generate profiles from /var/log/audit/audit.log
with apparmor-utils.
auditd needs the folder /var/log/audit to be present on start
so this is generated in ExecPreStart.
auditd starts with -s nochange so that effective audit processing
is managed by the audit.service.
* Create "full.pem" from selfsigned certificate
* Tell simp_le to create "full.pem"
* Inject service dependency between lighttpd and the generation of certificates
Side note: According to the internet these servers also use the
"full.pem" format: pound, ejabberd, pure-ftpd.
Adds an option `security.lockKernelModules` that, when enabled, disables
kernel module loading once the system reaches its normal operating state.
The rationale for this over simply setting the sysctl knob is to allow
some legitmate kernel module loading to occur; the naive solution breaks
too much to be useful.
The benefit to the user is to help ensure the integrity of the kernel
runtime: only code loaded as part of normal system initialization will be
available in the kernel for the duration of the boot session. This helps
prevent injection of malicious code or unexpected loading of legitimate
but normally unused modules that have exploitable bugs (e.g., DCCP use
after free CVE-2017-6074, n_hldc CVE-2017-2636, XFRM framework
CVE-2017-7184, L2TPv3 CVE-2016-10200).
From an aestethic point of view, enabling this option helps make the
configuration more "declarative".
Closes https://github.com/NixOS/nixpkgs/pull/24681
Upstream has decided to make -testing patches private, effectively ceasing
free support for grsecurity/PaX [1]. Consequently, we can no longer
responsibly support grsecurity on NixOS.
This patch turns the kernel and patch expressions into build errors and
adds a warning to the manual, but retains most of the infrastructure, in
an effort to make the transition smoother. For 17.09 all of it should
probably be pruned.
[1]: https://grsecurity.net/passing_the_baton.php
This reduces the time window during which IP addresses are gone during
switch-to-configuration. A complication is that with stopIfChanged =
true, preStop would try to delete the *new* IP addresses rather than
the old one (since the preStop script now runs after the switch to the
new configuration). So we now record the actually configured addresses
in /run/nixos/network/addresses/<interface>. This is more robust in
any case.
Issue https://github.com/NixOS/nixops/issues/640.
Commit 75f131da02 added
`chown 'nginx:nginx' '/var/lib/acme'` to the pre-start script,
but since it doesn't use `chown -R`, it is possible that there
are older existing subdirs (like `acme-challenge`)
that are owned to `root` from before that commit went it.
* The source attribute is mandatory, not optional
* The program attribute is optional
* Move the info about the mandatory attribute first (most important,
IMHO)
perlPackages.TextWrapI18N: init at 0.06
perlPackages.Po4a: init at 0.47
jade: init at 1.2.1
ding-libs: init at 0.6.0
Switch nscd to no-caching mode if SSSD is enabled.
abbradar: disable jade parallel building.
Closes#21150
`systemd.hideProcessInformation = true`, would break interactions
requiring polkit arbitration such as initating poweroff/reboot as a
normal user; the polkit daemon cannot be expected to make decisions
about processes that don't exist as far as it is concerned.
systemd-logind lacks the `sys_ptrace` capability and so needs to be part
of the designated proc gid, even though it runs as root.
Fixes https://github.com/NixOS/nixpkgs/issues/20948
Fairly severe, but can be disabled at bootup via
grsec_sysfs_restrict=0. For the NixOS module we ensure that it is
disabled, for systemd compatibility.
Previously, we would only set a default value, on the theory that
`boot.kernelPackages` could be used to sanely configure a custom grsec
kernel. Regrettably, this is not the case and users who expect e.g.,
`boot.kernelPackages = pkgs.linuxPackages_latest` to work will end up
with a non-grsec kernel (this problem has come up twice on the bug
tracker recently).
With this patch, `security.grsecurity.enable = true` implies
`boot.kernelPackages = linuxPackages_grsec_nixos` and any customization
must be done via package override or by eschewing the module.
Using a custom package set with the NixOS module is no longer
something I wish to support. It's still *possible* but not
advertised. Secondly, the requiredKernelConfig didn't really
do anything (setting kernelPackages to a non-grsec kernel would
just silently let the user boot into a non-grsec setup ...).
Previously, the list of CA certificates was generated with a perl script
which is included in curl. As this script is not very flexible, this commit
refactors the expression to use the python script that Debian uses to
generate their CA certificates from Mozilla's trust store in NSS.
Additionally, an option was added to the cacerts derivation and the
`security.pki` module to blacklist specific CAs.
It looks like the cpu type part of modalias might have changed, my
systems (4.4.20 and 4.7.2) show something like the following:
```
cpu:type:x86,ven0000fam0006mod003F:feature:,0000,0001,0002,0003,0004,0005,0006,0007,0008,0009,000B,000C,000D,000E,000F,0010,0011,0013,0017,0018,0019,001A,001C,002B,0034,003B,003D,0068,006F,0070,0072,0074,0075,0076,007D,0080,0081,0089,008C,008D,0091,0093,0094,0095,0096,0097,0098,0099,009A,009B,009C,009D,009E,009F,00C0,00C5,0120,0123,0125,0127,0128,0129,012A,0140
```
Update the rngd modalias rule to match this so udev properly has
systemd start rngd.
This reverts commit 1010271c63.
This reverts commit e85e51d41f.
The first commit causes multiple regressions. The second commit tries to
fix the regressions, but does not catch all of them. There are multiple
failing tests, one of which is blocking a package update. That is not
acceptable for a cosmetic patch.
Regression introduced by 1010271c63.
This caused the line after using the loginuid module to be concatenated
with the next line without a newline.
In turn this has caused a lot of the NixOS VM tests to either run very
slowly (because of constantly hitting PAM errors) or simply fail.
I have tested this only with one of the failing NixOS tests.
Signed-off-by: aszlig <aszlig@redmoonstudios.org>
The generated files in /etc/pam.d/ typically have a lot of empty lines
in them, due to how the generated Nix strings are joined together;
optional elements that are excluded still produce a newline. This patch
changes how the files are generated to create more compact,
human-friendly output files.
The change is basically this, repeated:
- ''
- ${optionalString use_ldap
- "account sufficient ${pam_ldap}/lib/security/pam_ldap.so"}
- ''
+ optionalString use_ldap ''
+ account sufficient ${pam_ldap}/lib/security/pam_ldap.so
+ ''
Before this commit updating /var/setuid-wrappers/ folder introduced
a small window where NixOS activation scripts could be terminated
and resulted into empty /var/setuid-wrappers/ folder.
That's very unfortunate because one might lose sudo binary.
Instead we use two atomic operations mv and ln (as described in
https://axialcorps.com/2013/07/03/atomically-replacing-files-and-directories/)
to achieve atomicity.
Since /var/setuid-wrappers is not a directory anymore, tmpfs mountpoints
were removed in installation scripts and in boot process.
Tested:
- upgrade /var/setuid-wrappers/ from folder to a symlink
- make sure /run/setuid-wrappers-dirs/ legacy symlink is really deleted
A new internal config option `fileSystems.<name>.early` is added to indicate
that the filesystem needs to be loaded very early (i.e. in initrd). They are
transformed to a shell script in `system.build.earlyMountScript` with calls to
an undefined `specialMount` function, which is expected to be caller-specific.
This option is used by stage-1, stage-2 and activation script to set up and
remount those filesystems. Options for them are updated according to systemd
defaults.
While useless, some builds may dabble with setuid bits (e.g.,
util-linux), which breaks under grsec. In the interest of user
friendliness, we once again compromise by disabling an otherwise useful
feature ...
Closes https://github.com/NixOS/nixpkgs/issues/17501
Closes#17460
Changed the wrapper derivation to produce a second output containing the sandbox.
Add a launch wrapper to try and locate the sandbox (either in /var/setuid-wrappers or in /nix/store).
This launch wrapper also sheds libredirect.so from LD_PRELOAD as Chromium does not tolerate it.
Does not trigger a Chromium rebuild.
cc @cleverca22 @joachifm @jasom
Enabling EFI runtime services provides a venue for injecting code into
the kernel.
When grsecurity is enabled, we close this by default by disabling access
to EFI runtime services. The upshot of this is that
/sys/firmware/efi/efivars will be unavailable by default (and attempts
to mount it will fail).
This is not strictly a grsecurity related option, it could be made into
a general option, but it seems to be of particular interest to
grsecurity users (for non-grsecurity users, there are other, more
immediate kernel injection attack dangers to contend with anyway).
