Message ID | 877dlzb17k.fsf@muradm.net |
---|---|
State | Accepted |
Headers | show |
Series | [bug#47323] services: export sysctl-configuration record field accessors | expand |
Context | Check | Description |
---|---|---|
cbaines/submitting builds | success | |
cbaines/comparison | success | View comparision |
cbaines/git branch | success | View Git branch |
cbaines/applying patch | fail | View Laminar job |
cbaines/issue | success | View issue |
As per discussion with Leo on IRC #guix in relation to #47013 and #47323. There is a need to have important sysctl settings fs.protected_hardlinks and fs.protected_symlinks for all installations of Guix in the world unless explicitly stated otherwise. Currently in Linux kernel they are unset by default. It is also stated that other distributions do the same. In perfect world I would go for Solution 1 below, as it is most effectful, and clean. Solution 1: From this statement, it seems that the first resort whould be Linux kernel it self. If it would be possible to configure them with Kconfig, that would be best place. As of my brief look at linux/fs, they are not configurable, but may be I miss somthing. Any way preferred solution would be just compile kernel with protected hardlinks and symlinks set to 1. Since other distributions do the same, it could be reasonable to expose these two settings via Kconfig, and solve it there. - pros: great for the world - cons: have to do enhancement in mainline Linux Solution 2: If it is not possible to have these two settings in kernel as per Solution 1, Guix may maintain a patch to kernel that would do this. - pros: no need to enhance mainline Linux - cons: will impact users who do use Guix and compile Linux kernel them selves Solution 3: Handle in Guix configuration. Everything below related to solution 3 and current issue #47323. Currently it is set as folowing: ;; gnu/services/sysctl.scm (define-module .... #:export (.... %default-sysctl-settings) (define %default-sysctl-settings ;; Default kernel parameters enabled with sysctl. '(("fs.protected_hardlinks" . "1") ("fs.protected_symlinks" . "1"))) (define-record-type* <sysctl-configuration> sysctl-configuration make-sysctl-configuration sysctl-configuration? (sysctl sysctl-configuration-sysctl ; path of the 'sysctl' command (default (file-append procps "/sbin/sysctl"))) (settings sysctl-configuration-settings ; alist of string pairs (default %default-sysctl-settings))) ;; ends- gnu/services/sysctl.scm And sysctl-service-type it self is added to the %base-services. Since sysctl-configuration-settings function to access settings field of sysctl-configuration instance is not exported, I have to do the following in my configuration: (define nomad-gx1-os (operating-system (inherit my-base-nomad-os) ;; important line-#1 ... (services (modify-services my-base-nomad-services (sysctl-service-type config => (inherit config) (settings (append %default-sysctl-settings ;; from gnu/services/sysctl.scm '(("fs.inotify.max_user_watches" . "524288") ("fs.inotify.max_user_instances" . "16384") ("fs.inotify.max_queued_events" . "65536"))))))))) This is fine, until I extend sysctl-service-type in my-base-nomad-os. Then I have to export my-base-nomad-sysctl-settings and join them with %default-sysctl-settings and extra settings for nomad-gx1-os. While it is bearable for one or two levels of inheritance, it becomes hard to keep track for more levels and/or many hosts. If sysctl-configuration-settings would be exported, then my configuration would become simplier: (services (modify-services my-base-nomad-services (sysctl-service-type config => (inherit config) (settings (append (sysctl-configuration-settings config) ;; now I can't do this '(("fs.inotify.max_user_watches" . "524288") ("fs.inotify.max_user_instances" . "16384") ("fs.inotify.max_queued_events" . "65536"))))))))) In this case, if Guix documentation will include sysctl-configuration-settings, then most likely people won't forget use %default-sysctl-settings, and it is still possible to override them if one desires not to use protected symlinks and hardlinks.
Hi, muradm <mail@muradm.net> skribis: >>From 0928d70c1cd5a98efd7671c05b38757400941790 Mon Sep 17 00:00:00 2001 > From: muradm <mail@muradm.net> > Date: Mon, 22 Mar 2021 19:09:48 +0300 > Subject: [PATCH] services: export sysctl-configuration record field accessors > > * gnu/services/sysctl.scm (sysctl-configuration-sysctl): new public function > * gnu/services/sysctl.scm (sysctl-configuration-settings): new public function > > Signed-off-by: muradm <mail@muradm.net> I tweaked the commit log and applied. > As per discussion with Leo on IRC #guix in relation to #47013 and > #47323. > > There is a need to have important sysctl settings > fs.protected_hardlinks and fs.protected_symlinks for all > installations of Guix in the world unless explicitly stated > otherwise. Currently in Linux kernel they are unset by default. It > is also stated that other distributions do the same. > > In perfect world I would go for Solution 1 below, as it is most > effectful, and clean. > > Solution 1: From this statement, it seems that the first resort > whould be Linux kernel it self. If it would be possible to > configure them with Kconfig, that would be best place. As of my > brief look at linux/fs, they are not configurable, but may be I > miss somthing. Any way preferred solution would be just compile > kernel with protected hardlinks and symlinks set to 1. Since other > distributions do the same, it could be reasonable to expose these > two settings via Kconfig, and solve it there. > - pros: great for the world > - cons: have to do enhancement in mainline Linux > > Solution 2: If it is not possible to have these two settings in > kernel as per Solution 1, Guix may maintain a patch to kernel that > would do this. > - pros: no need to enhance mainline Linux > - cons: will impact users who do use Guix and compile Linux kernel > them selves > > Solution 3: Handle in Guix configuration. Everything below related > to solution 3 and current issue #47323. > > Currently it is set as folowing: > > ;; gnu/services/sysctl.scm > (define-module .... > #:export (.... > %default-sysctl-settings) > > (define %default-sysctl-settings > ;; Default kernel parameters enabled with sysctl. > '(("fs.protected_hardlinks" . "1") > ("fs.protected_symlinks" . "1"))) > > (define-record-type* <sysctl-configuration> > sysctl-configuration make-sysctl-configuration > sysctl-configuration? > (sysctl sysctl-configuration-sysctl ; path of the 'sysctl' > command > (default (file-append procps "/sbin/sysctl"))) > (settings sysctl-configuration-settings ; alist of string pairs > (default %default-sysctl-settings))) > > ;; ends- gnu/services/sysctl.scm > > And sysctl-service-type it self is added to the > %base-services. Since sysctl-configuration-settings function to > access settings field of sysctl-configuration instance is not > exported, I have to do the following in my configuration: > > (define nomad-gx1-os > (operating-system > (inherit my-base-nomad-os) ;; important line-#1 > ... > (services > (modify-services my-base-nomad-services > (sysctl-service-type config => > (inherit config) > (settings > (append > %default-sysctl-settings ;; from > gnu/services/sysctl.scm > '(("fs.inotify.max_user_watches" . "524288") > ("fs.inotify.max_user_instances" . "16384") > ("fs.inotify.max_queued_events" . "65536"))))))))) > > This is fine, until I extend sysctl-service-type in > my-base-nomad-os. Then I have to export > my-base-nomad-sysctl-settings and join them with > %default-sysctl-settings and extra settings for > nomad-gx1-os. While it is bearable for one or two levels of > inheritance, it becomes hard to keep track for more levels and/or > many hosts. > > If sysctl-configuration-settings would be exported, > then my configuration would become simplier: > > (services > (modify-services my-base-nomad-services > (sysctl-service-type config => > (inherit config) > (settings > (append > (sysctl-configuration-settings config) ;; now I can't > do this > '(("fs.inotify.max_user_watches" . "524288") > ("fs.inotify.max_user_instances" . "16384") > ("fs.inotify.max_queued_events" . "65536"))))))))) > > In this case, if Guix documentation will include > sysctl-configuration-settings, then most likely people won't > forget use %default-sysctl-settings, and it is still possible to > override them if one desires not to use protected symlinks and > hardlinks. Indeed, this is a discussion Leo Famulari and I had while preparing the patch for this security issue. Like you write, there are different tradeoffs, and this solution is one possibility that looked reasonable. Thanks! Ludo’.
From 0928d70c1cd5a98efd7671c05b38757400941790 Mon Sep 17 00:00:00 2001 From: muradm <mail@muradm.net> Date: Mon, 22 Mar 2021 19:09:48 +0300 Subject: [PATCH] services: export sysctl-configuration record field accessors * gnu/services/sysctl.scm (sysctl-configuration-sysctl): new public function * gnu/services/sysctl.scm (sysctl-configuration-settings): new public function Signed-off-by: muradm <mail@muradm.net> --- gnu/services/sysctl.scm | 2 ++ 1 file changed, 2 insertions(+) diff --git a/gnu/services/sysctl.scm b/gnu/services/sysctl.scm index aaea7cc30d..80ed2ff46f 100644 --- a/gnu/services/sysctl.scm +++ b/gnu/services/sysctl.scm @@ -25,6 +25,8 @@ #:use-module (srfi srfi-1) #:use-module (ice-9 match) #:export (sysctl-configuration + sysctl-configuration-sysctl + sysctl-configuration-settings sysctl-service-type %default-sysctl-settings)) -- 2.31.0