[bug#49540] [PATCH 0/2] services: nftables: Make it extandable

[bug#49540] [PATCH 0/2] services: nftables: Make it extandable

[Brice Waegeneire]

This patchset make "nftables-service-type" extendable, so other services could
open port.  I wrote this to be able to use libvirt with nftables (another
patch is comming about that) like this:

--8<---------------cut here---------------start------------->8---
(simple-service 'nftables-libvirt nftables-service-type
                   (list "# Libvirt?
add rule inet guix forward ct state established,related accept
add rule inet guix forward iifname \"virbr*\" accept

add chain inet guix libvirt
insert rule inet guix input iifname \"virbr*\" jump libvirt
insert rule inet guix libvirt udp dport 53 accept
insert rule inet guix libvirt tcp dport 53 accept
insert rule inet guix libvirt udp dport 67 accept
"))
--8<---------------cut here---------------end--------------->8---

So this should make it possible to implement Solene's
"simple-firewall-service"¹ by simply extending "nftables-service-type".

Also, now, stopping nftables only remove the "guix" table so other software
can use their own namespaces without being purged when that service is
stopped.

WDYT?

¹ <https://issues.guix.gnu.org/48975>

Brice Waegeneire (2): services: nftables: Only manage delete our
own table.  services: nftables: Make it extendable.

 gnu/services/networking.scm | 51 +++++++++++++++++++++++++++++--------
 1 file changed, 41 insertions(+), 10 deletions(-)

-- 
2.31.1

[bug#49540] [PATCH 1/2] services: nftables: Only manage delete our own table.

[Brice Waegeneire]

* gnu/services/networking.scm (%default-nftables-ruleset): Rename table
  from "forward" to "guix".  Clear table before applying before setting
  it up.
(nftables-shepherd-service): Don't flush all the table, just delete our
  own.
---
 gnu/services/networking.scm | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/gnu/services/networking.scm b/gnu/services/networking.scm
index 1ae58041d3..3058c14caf 100644
--- a/gnu/services/networking.scm
+++ b/gnu/services/networking.scm
@@ -13,7 +13,7 @@
 ;;; Copyright © 2019, 2021 Maxim Cournoyer <maxim.cournoyer@gmail.com>
 ;;; Copyright © 2019 Sou Bunnbu <iyzsong@member.fsf.org>
 ;;; Copyright © 2019 Alex Griffin <a@ajgrf.com>
-;;; Copyright © 2020 Brice Waegeneire <brice@waegenei.re>
+;;; Copyright © 2020, 2021 Brice Waegeneire <brice@waegenei.re>
 ;;; Copyright © 2021 Oleg Pykhalov <go.wigust@gmail.com>
 ;;; Copyright © 2021 Christopher Lemmer Webber <cwebber@dustycloud.org>
 ;;; Copyright © 2021 Maxime Devos <maximedevos@telenet.be>
@@ -1717,7 +1717,12 @@ COMMIT
 (define %default-nftables-ruleset
   (plain-file "nftables.conf"
               "# A simple and safe firewall
-table inet filter {
+
+# Start with our table clean of previous state
+add table inet guix
+delete table inet guix
+
+table inet guix {
   chain input {
     type filter hook input priority 0; policy drop;
 
@@ -1768,7 +1773,7 @@ table inet filter {
         (start #~(lambda _
                    (invoke #$nft "--file" #$ruleset)))
         (stop #~(lambda _
-                  (invoke #$nft "flush" "ruleset"))))))))
+                  (invoke #$nft "delete" "table" "inet" "guix"))))))))
 
 (define nftables-service-type
   (service-type
-- 
2.31.1

[bug#49540] [PATCH 2/2] services: nftables: Make it extendable.

[Brice Waegeneire]

* gnu/services/networking.scm (%default-nftables-rules): New variable…
(define-record-type): …replace %default-nftables-ruleset with it.
(%default-nftables-ruleset): Deprecate it.
(nftables-ruleset): New procedure…
(nftables-shepherd-service): …use it.
(nftables-service-type): Make it extendable.
---
 gnu/services/networking.scm | 40 ++++++++++++++++++++++++++++++-------
 1 file changed, 33 insertions(+), 7 deletions(-)

diff --git a/gnu/services/networking.scm b/gnu/services/networking.scm
index 3058c14caf..53c06dcfed 100644
--- a/gnu/services/networking.scm
+++ b/gnu/services/networking.scm
@@ -1714,9 +1714,8 @@ COMMIT
 ;;; nftables
 ;;;
 
-(define %default-nftables-ruleset
-  (plain-file "nftables.conf"
-              "# A simple and safe firewall
+(define %default-nftables-rules
+  "# A simple and safe firewall
 
 # Start with our table clean of previous state
 add table inet guix
@@ -1752,7 +1751,11 @@ table inet guix {
     type filter hook output priority 0; policy accept;
   }
 }
-"))
+")
+
+(define-deprecated %default-nftables-ruleset
+  %default-nftables-rules
+  (plain-file "nftables.conf" %default-nftables-rules))
 
 (define-record-type* <nftables-configuration>
   nftables-configuration
@@ -1760,13 +1763,28 @@ table inet guix {
   nftables-configuration?
   (package nftables-configuration-package
            (default nftables))
-  (ruleset nftables-configuration-ruleset ; file-like object
-           (default %default-nftables-ruleset)))
+  ; file-like object | list of strings and file-like objects
+  (ruleset nftables-configuration-ruleset
+           (default (list %default-nftables-rules))))
+
+(define (nftables-ruleset ruleset)
+  (if (file-like? ruleset)
+      ruleset
+      (apply mixed-text-file
+             `("nftables.conf"
+               ,@(fold-right
+                 (lambda (rule result)
+                   (if (file-like? rule)
+                       (append (list "include \"" rule "\"\n") result)
+                       (append (list rule "\n") result)))
+                 '()
+                 ruleset)))))
 
 (define nftables-shepherd-service
   (match-lambda
     (($ <nftables-configuration> package ruleset)
-     (let ((nft (file-append package "/sbin/nft")))
+     (let ((nft (file-append package "/sbin/nft"))
+           (ruleset (nftables-ruleset ruleset)))
        (shepherd-service
         (documentation "Packet filtering and classification")
         (provision '(nftables))
@@ -1785,6 +1803,14 @@ table inet guix {
                              (compose list nftables-shepherd-service))
           (service-extension profile-service-type
                              (compose list nftables-configuration-package))))
+   (compose concatenate)
+   (extend (lambda (config additional-rules)
+             (let ((ruleset (nftables-configuration-ruleset config)))
+               (nftables-configuration
+                (inherit config)
+                (ruleset (if (list? ruleset)
+                             (append ruleset additional-rules)
+                             (cons* ruleset additional-rules)))))))
    (default-value (nftables-configuration))))
 
 \f
-- 
2.31.1