The chroot caps restriction disallows chroot'ed processes from running
any command that requires `CAP_SYS_ADMIN`, breaking `nixos-rebuild`. See
e.g., https://github.com/NixOS/nixpkgs/issues/15293
This significantly weakens chroot protections, but to break
nixos-rebuild out of the box is too severe.
The list of public proxies is updated now and again and it's probably a
good idea to always work from the most recent list, rather than the one
that is shipped with the release. This can be crucial in case of
resolvers that are revealed to have gone rogue or otherwise have been
compromised.
Unfortunately, pkill doesn't distinguish between kernel and user space
processes, so we need to make sure we don't accidentally kill kernel
threads.
Normally, a kernel thread ignores all signals, but there are a few that
do. A quick grep on the kernel source tree (as of kernel 4.6.0) shows
the following source files which use allow_signal():
drivers/isdn/mISDN/l1oip_core.c
drivers/md/md.c
drivers/misc/mic/cosm/cosm_scif_server.c
drivers/misc/mic/cosm_client/cosm_scif_client.c
drivers/net/wireless/broadcom/brcm80211/brcmfmac/sdio.c
drivers/staging/rtl8188eu/core/rtw_cmd.c
drivers/staging/rtl8712/rtl8712_cmd.c
drivers/target/iscsi/iscsi_target.c
drivers/target/iscsi/iscsi_target_login.c
drivers/target/iscsi/iscsi_target_nego.c
drivers/usb/atm/usbatm.c
drivers/usb/gadget/function/f_mass_storage.c
fs/jffs2/background.c
fs/lockd/clntlock.c
fs/lockd/svc.c
fs/nfs/nfs4state.c
fs/nfsd/nfssvc.c
While not all of these are necessarily kthreads and some functionality
may still be unimpeded, it's still quite harmful and can cause
unexpected side-effects, especially because some of these kthreads are
storage-related (which we obviously don't want to kill during bootup).
During discussion at #15226, @dezgeg suggested the following
implementation:
for pid in $(pgrep -v -f '@'); do
if [ "$(cat /proc/$pid/cmdline)" != "" ]; then
kill -9 "$pid"
fi
done
This has a few downsides:
* User space processes which use an empty string in their command line
won't be killed.
* It results in errors during bootup because some shell-related
processes are already terminated (maybe it's pgrep itself, haven't
checked).
* The @ is searched within the full command line, not just at the
beginning of the string. Of course, we already had this until now, so
it's not a problem of his implementation.
I posted an alternative implementation which doesn't suffer from the
first point, but even that one wasn't sufficient:
for pid in $(pgrep -v -f '^@'); do
readlink "/proc/$pid/exe" &> /dev/null || continue
echo "$pid"
done | xargs kill -9
This one spawns a subshell, which would be included in the processes to
kill and actually kills itself during the process.
So what we have now is even checking whether the shell process itself is
in the list to kill and avoids killing it just to be sure.
Also, we don't spawn a subshell anymore and use /proc/$pid/exe to
distinguish between user space and kernel processes like in the comments
of the following StackOverflow answer:
http://stackoverflow.com/a/12231039
We don't need to take care of terminating processes, because what we
actually want IS to terminate the processes.
The only point where this (and any previous) approach falls short if we
have processes that act like fork bombs, because they might spawn
additional processes between the pgrep and the killing. We can only
address this with process/control groups and this still won't save us
because the root user can escape from that as well.
Signed-off-by: aszlig <aszlig@redmoonstudios.org>
Fixes: #15226
Instead of using this option, please modify the dovecot package by means of an
override. For example:
nixpkgs.config.packageOverrides = super: {
dovecot = super.dovecot.override { withPgSQL = true; };
};
Closes https://github.com/NixOS/nixpkgs/issues/14097.
* Perform HTTP HEAD request instead of full GET (lighter weight)
* Don't log output of curl to the journal (it's noise/debug)
* Use explicit http:// URL scheme
* Reduce poll interval from 10s to 2s (respond to state changes
quicker). Probably not relevant on boot (lots of services compete for
the CPU), but online service restarts/reloads should be quicker.
* Pass --fail to curl (should be more robust against false positives)
* Use 4 space indent for shell code.
The current postStart code holds Jenkins off the "started" state until
Jenkins becomes idle. But it should be enough to wait until Jenkins
start handling HTTP requests to consider it "started".
More reasons why the current approach is bad and we should remove it,
from @coreyoconnor in
https://github.com/NixOS/nixpkgs/issues/14991#issuecomment-216572571:
1. Repeatedly curling for a specific human-readable string to
determine "Active" is fragile. For instance, what happens when jenkins
is localized?
2. The time jenkins takes to initializes is variable. This (at least
used to) depend on the number of jobs and any plugin upgrades requested.
3. Jenkins can be requested to restart from the UI. Which will not
affect the status of the service. This means that the service being
"active" does not imply jenkins is initialized. Downstream services
cannot assume jenkins is initialized if the service is active. Might
as well accept that and remove the initialized test from service
startup.
Fixes#14991.
A sane backend for recent brother scanners.
Depends on the presence of etc files generated by the
nixos module of the same name.
Supports network scanner specification through the
nixos module.
The Nix store squashfs is stored inside the initrd instead of separately
(cherry picked from commit 976fd407796877b538c470d3a5253ad3e1f7bc68)
Signed-off-by: Domen Kožar <domen@dev.si>
A user noticed the example for `hosts`, took the `mode` permissions literally, and ended up with surprising behavior on their system. Updating the documentation to not reference a real config file which might have real permissions requirements.
