diff options
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.txt | 5 | ||||
| -rw-r--r-- | Documentation/admin-guide/sysctl/net.rst | 20 | ||||
| -rw-r--r-- | include/linux/netdevice.h | 8 | ||||
| -rw-r--r-- | net/core/sysctl_net_core.c | 17 |
4 files changed, 40 insertions, 10 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index a1068742a6df..8af893ef0d46 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -1338,6 +1338,11 @@ Format: <interval>,<probability>,<space>,<times> See also Documentation/fault-injection/. + fb_tunnels= [NET] + Format: { initns | none } + See Documentation/admin-guide/sysctl/net.rst for + fb_tunnels_only_for_init_ns + floppy= [HW] See Documentation/admin-guide/blockdev/floppy.rst. diff --git a/Documentation/admin-guide/sysctl/net.rst b/Documentation/admin-guide/sysctl/net.rst index 42cd04bca548..57fd6ce68fe0 100644 --- a/Documentation/admin-guide/sysctl/net.rst +++ b/Documentation/admin-guide/sysctl/net.rst @@ -300,7 +300,6 @@ Note: 0: 0 1 2 3 4 5 6 7 RSS hash key: 84:50:f4:00:a8:15:d1:a7:e9:7f:1d:60:35:c7:47:25:42:97:74:ca:56:bb:b6:a1:d8:43:e3:c9:0c:fd:17:55:c2:3a:4d:69:ed:f1:42:89 - netdev_tstamp_prequeue ---------------------- @@ -321,11 +320,20 @@ fb_tunnels_only_for_init_net ---------------------------- Controls if fallback tunnels (like tunl0, gre0, gretap0, erspan0, -sit0, ip6tnl0, ip6gre0) are automatically created when a new -network namespace is created, if corresponding tunnel is present -in initial network namespace. -If set to 1, these devices are not automatically created, and -user space is responsible for creating them if needed. +sit0, ip6tnl0, ip6gre0) are automatically created. There are 3 possibilities +(a) value = 0; respective fallback tunnels are created when module is +loaded in every net namespaces (backward compatible behavior). +(b) value = 1; [kcmd value: initns] respective fallback tunnels are +created only in init net namespace and every other net namespace will +not have them. +(c) value = 2; [kcmd value: none] fallback tunnels are not created +when a module is loaded in any of the net namespace. Setting value to +"2" is pointless after boot if these modules are built-in, so there is +a kernel command-line option that can change this default. Please refer to +Documentation/admin-guide/kernel-parameters.txt for additional details. + +Not creating fallback tunnels gives control to userspace to create +whatever is needed only and avoid creating devices which are redundant. Default : 0 (for compatibility reasons) diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index b8abe1d7aa0b..c0b512e6a02b 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -640,10 +640,14 @@ struct netdev_queue { extern int sysctl_fb_tunnels_only_for_init_net; extern int sysctl_devconf_inherit_init_net; +/* + * sysctl_fb_tunnels_only_for_init_net == 0 : For all netns + * == 1 : For initns only + * == 2 : For none. + */ static inline bool net_has_fallback_tunnels(const struct net *net) { - return net == &init_net || - !IS_ENABLED(CONFIG_SYSCTL) || + return (net == &init_net && sysctl_fb_tunnels_only_for_init_net == 1) || !sysctl_fb_tunnels_only_for_init_net; } diff --git a/net/core/sysctl_net_core.c b/net/core/sysctl_net_core.c index 6ada114bbcca..d86d8d11cfe4 100644 --- a/net/core/sysctl_net_core.c +++ b/net/core/sysctl_net_core.c @@ -22,7 +22,7 @@ #include <net/busy_poll.h> #include <net/pkt_sched.h> -static int two __maybe_unused = 2; +static int two = 2; static int three = 3; static int min_sndbuf = SOCK_MIN_SNDBUF; static int min_rcvbuf = SOCK_MIN_RCVBUF; @@ -546,7 +546,7 @@ static struct ctl_table net_core_table[] = { .mode = 0644, .proc_handler = proc_dointvec_minmax, .extra1 = SYSCTL_ZERO, - .extra2 = SYSCTL_ONE, + .extra2 = &two, }, { .procname = "devconf_inherit_init_net", @@ -587,6 +587,19 @@ static struct ctl_table netns_core_table[] = { { } }; +static int __init fb_tunnels_only_for_init_net_sysctl_setup(char *str) +{ + /* fallback tunnels for initns only */ + if (!strncmp(str, "initns", 6)) + sysctl_fb_tunnels_only_for_init_net = 1; + /* no fallback tunnels anywhere */ + else if (!strncmp(str, "none", 4)) + sysctl_fb_tunnels_only_for_init_net = 2; + + return 1; +} +__setup("fb_tunnels=", fb_tunnels_only_for_init_net_sysctl_setup); + static __net_init int sysctl_core_net_init(struct net *net) { struct ctl_table *tbl; |