| Message ID | b39b1b4304524c43dfd83280aea4cfb4e8ac97f5.1523959377.git.mschiffer@universe-factory.net |
|---|---|
| State | Changes Requested, archived |
| Delegated to: | David Miller |
| Headers | show |
| Series | [RESEND,net-next] ipv6: provide Kconfig switch to disable accept_ra by default | expand |
From: Matthias Schiffer <mschiffer@universe-factory.net> Date: Tue, 17 Apr 2018 12:04:50 +0200 > Many distributions and users prefer to handle router advertisements in > userspace; one example is OpenWrt, which includes a combined RA and DHCPv6 > client. For such configurations, accept_ra should not be enabled by > default. > > As setting net.ipv6.conf.default.accept_ra via sysctl.conf or similar > facilities may be too late to catch all interfaces and common sysctl.conf > tools do not allow setting an option for all existing interfaces, this > patch provides a Kconfig option to control the default value of > default.accept_ra. > > Using default.accept_ra is preferable to all.accept_ra for our usecase, > as disabling all.accept_ra would preclude users from explicitly enabling > accept_ra on individual interfaces. > > Signed-off-by: Matthias Schiffer <mschiffer@universe-factory.net> This kind of Kconfig option makes an irreversible behavior choice at compile time, which satisfies one set of users whilst completely precluding another set. So no matter what setting a distribution chooses, one set of users are basically out of luck. For that reason I consider this a poor approach. I hate module options, but at least with that the user can choose regardless of what the distribution maker decided to do with their kernel. This is essentially how we handle "disable_ipv6" I'm not applying this, because it is as much of a step backwards as it is a step forward, sorry.
diff --git a/net/ipv6/Kconfig b/net/ipv6/Kconfig index 6794ddf0547c..0f453110f288 100644 --- a/net/ipv6/Kconfig +++ b/net/ipv6/Kconfig @@ -20,6 +20,18 @@ menuconfig IPV6 if IPV6 +config IPV6_ACCEPT_RA_DEFAULT + bool "IPv6: Accept router advertisements by default" + default y + help + The kernel can internally handle IPv6 router advertisements for + stateless address autoconfiguration (SLAAC) and route configuration, + which can be configured in detail and per-interface using a number of + sysctl options. This option controls the default value of + net.ipv6.conf.default.accept_ra. + + If unsure, say Y. + config IPV6_ROUTER_PREF bool "IPv6: Router Preference (RFC 4191) support" ---help--- diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c index 62b97722722c..5fd6d2120a35 100644 --- a/net/ipv6/addrconf.c +++ b/net/ipv6/addrconf.c @@ -245,7 +245,7 @@ static struct ipv6_devconf ipv6_devconf_dflt __read_mostly = { .forwarding = 0, .hop_limit = IPV6_DEFAULT_HOPLIMIT, .mtu6 = IPV6_MIN_MTU, - .accept_ra = 1, + .accept_ra = IS_ENABLED(CONFIG_IPV6_ACCEPT_RA_DEFAULT), .accept_redirects = 1, .autoconf = 1, .force_mld_version = 0,
Many distributions and users prefer to handle router advertisements in userspace; one example is OpenWrt, which includes a combined RA and DHCPv6 client. For such configurations, accept_ra should not be enabled by default. As setting net.ipv6.conf.default.accept_ra via sysctl.conf or similar facilities may be too late to catch all interfaces and common sysctl.conf tools do not allow setting an option for all existing interfaces, this patch provides a Kconfig option to control the default value of default.accept_ra. Using default.accept_ra is preferable to all.accept_ra for our usecase, as disabling all.accept_ra would preclude users from explicitly enabling accept_ra on individual interfaces. Signed-off-by: Matthias Schiffer <mschiffer@universe-factory.net> --- net/ipv6/Kconfig | 12 ++++++++++++ net/ipv6/addrconf.c | 2 +- 2 files changed, 13 insertions(+), 1 deletion(-)