This reverts commit 43c6d5abacaebf813845934ec8d5e5ee3c431854.
It turns out we don't actually need to set the global ip_forward setting
for it to work on a per interface basis.
What this toggle actually does is switch forwarding on/off for all
currently present interfaces and change the default for new ones.
That means that by setting this we
- Introduce a race condition, because if the interface with IPForward=yes
is brought up after one without it, both will have forwarding enabled.
The other way around networkd forces it off for the one with IPForward=no
- Change the forwarding setting for interfaces that networkd is not
configured to touch, even if the user disabled forwarding globally via
/proc/sys/net/ipv4/ip_forward = 0
As forwarding works fine without this, as long as all relevant
interfaces individually set IPForward=yes: just drop it
This means that non-networkd interfaces use the global default while
networkd interfaces default to off if IPForward isn't given.
---
man/systemd.network.xml | 4 +---
src/network/networkd-link.c | 28 +---------------------------
2 files changed, 2 insertions(+), 30 deletions(-)
diff --git a/man/systemd.network.xml b/man/systemd.network.xml
index 4be9d13..31484d8 100644
--- a/man/systemd.network.xml
+++ b/man/systemd.network.xml
@@ -373,9 +373,7 @@
globally turned on in the kernel, with the
<filename>net.ipv4.ip_forward</filename> and
<filename>net.ipv4.ip_forward</filename> sysctl
- options. Also, if this option is enabled for at least one
- interface, the global options in the kernel are also enabled
- as necessary, to ensure IP forwarding can take place.</para>
+ options.</para>
</listitem>
</varlistentry>
<varlistentry>
diff --git a/src/network/networkd-link.c b/src/network/networkd-link.c
index ab115a0..c7f7c9b 100644
--- a/src/network/networkd-link.c
+++ b/src/network/networkd-link.c
@@ -1485,39 +1485,13 @@ static int link_enter_join_netdev(Link *link) {
static int link_set_ipv4_forward(Link *link) {
const char *p = NULL;
- bool b;
int r;
- b = link_ipv4_forward_enabled(link);
-
p = strjoina("/proc/sys/net/ipv4/conf/", link->ifname, "/forwarding");
- r = write_string_file_no_create(p, one_zero(b));
+ r = write_string_file_no_create(p,
one_zero(link_ipv4_forward_enabled(link)));
if (r < 0)
log_link_warning_errno(link, r, "Cannot configure IPv4
forwarding for interface %s: %m", link->ifname);
- if (b) {
- _cleanup_free_ char *buf = NULL;
-
- /* If IP forwarding is turned on for this interface,
- * then propagate this to the global setting. Given
- * that turning this on has side-effects on other
- * fields, we'll try to avoid doing this unless
- * necessary, hence check the previous value
- * first. Note that we never turn this option off
- * again, since all interfaces we manage do not do
- * forwarding anyway by default, and ownership rules
- * of this control are so unclear. */
-
- r = read_one_line_file("/proc/sys/net/ipv4/ip_forward", &buf);
- if (r < 0)
- log_link_warning_errno(link, r, "Cannot read
/proc/sys/net/ipv4/ip_forward: %m");
- else if (!streq(buf, "1")) {
- r =
write_string_file_no_create("/proc/sys/net/ipv4/ip_forward", "1");
- if (r < 0)
- log_link_warning_errno(link, r, "Cannot write
/proc/sys/net/ipv4/ip_forward: %m");
- }
- }
-
return 0;
}
--
2.3.3
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