linux/net/ipv6
Alex Henrie 629df6701c net: ipv6/addrconf: clamp preferred_lft to the minimum required
If the preferred lifetime was less than the minimum required lifetime,
ipv6_create_tempaddr would error out without creating any new address.
On my machine and network, this error happened immediately with the
preferred lifetime set to 1 second, after a few minutes with the
preferred lifetime set to 4 seconds, and not at all with the preferred
lifetime set to 5 seconds. During my investigation, I found a Stack
Exchange post from another person who seems to have had the same
problem: They stopped getting new addresses if they lowered the
preferred lifetime below 3 seconds, and they didn't really know why.

The preferred lifetime is a preference, not a hard requirement. The
kernel does not strictly forbid new connections on a deprecated address,
nor does it guarantee that the address will be disposed of the instant
its total valid lifetime expires. So rather than disable IPv6 privacy
extensions altogether if the minimum required lifetime swells above the
preferred lifetime, it is more in keeping with the user's intent to
increase the temporary address's lifetime to the minimum necessary for
the current network conditions.

With these fixes, setting the preferred lifetime to 3 or 4 seconds "just
works" because the extra fraction of a second is practically
unnoticeable. It's even possible to reduce the time before deprecation
to 1 or 2 seconds by also disabling duplicate address detection (setting
/proc/sys/net/ipv6/conf/*/dad_transmits to 0). I realize that that is a
pretty niche use case, but I know at least one person who would gladly
sacrifice performance and convenience to be sure that they are getting
the maximum possible level of privacy.

Link: https://serverfault.com/a/1031168/310447
Signed-off-by: Alex Henrie <alexhenrie24@gmail.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://lore.kernel.org/r/20231024212312.299370-3-alexhenrie24@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2023-10-25 18:23:06 -07:00
..
ila ila: Remove unnecessary file net/ila.h 2023-08-02 12:28:16 -07:00
netfilter netfilter: xt_mangle: only check verdict part of return value 2023-10-18 10:26:43 +02:00
addrconf_core.c net: rename reference+tracking helpers 2022-06-09 21:52:55 -07:00
addrconf.c net: ipv6/addrconf: clamp preferred_lft to the minimum required 2023-10-25 18:23:06 -07:00
addrlabel.c ipv6: addrlabel: fix infoleak when sending struct ifaddrlblmsg to network 2022-11-07 12:26:15 +00:00
af_inet6.c bpf: Propagate modified uaddrlen from cgroup sockaddr programs 2023-10-11 15:03:40 -07:00
ah6.c net: ipv6: Remove completion function scaffolding 2023-02-13 18:35:15 +08:00
anycast.c IPv6: add extack info for IPv6 address add/delete 2023-07-28 11:01:56 +01:00
calipso.c cipso,calipso: resolve a number of problems with the DOI refcounts 2021-03-04 15:26:57 -08:00
datagram.c ipv6: lockless IPV6_FLOWINFO_SEND implementation 2023-09-15 10:33:48 +01:00
esp6_offload.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2023-06-22 18:40:38 -07:00
esp6.c net: ipv6: fix return value check in esp_remove_trailer 2023-10-10 09:55:35 +02:00
exthdrs_core.c ipv6: Fix out-of-bounds access in ipv6_find_tlv() 2023-05-24 08:43:39 +01:00
exthdrs_offload.c
exthdrs.c ipv6: exthdrs: Replace opencoded swap() implementation 2023-08-08 15:36:47 -07:00
fib6_notifier.c
fib6_rules.c ipv6: change fib6_rules_net_exit() to batch mode 2022-02-08 20:41:34 -08:00
fou6.c
icmp.c ipv6: lockless IPV6_DONTFRAG implementation 2023-09-15 10:33:47 +01:00
inet6_connection_sock.c net: implement lockless SO_PRIORITY 2023-10-01 19:09:54 +01:00
inet6_hashtables.c net: remove duplicate INDIRECT_CALLABLE_DECLARE of udp[6]_ehashfn 2023-07-31 13:53:10 -07:00
ioam6_iptunnel.c ipv6: ioam: Insertion frequency in lwtunnel output 2022-02-04 20:24:45 -08:00
ioam6.c genetlink: start to validate reserved header bytes 2022-08-29 12:47:15 +01:00
ip6_checksum.c
ip6_fib.c net/ipv6: Remove expired routes with a separated list of routes. 2023-08-16 12:26:43 +01:00
ip6_flowlabel.c ipv6: move np->repflow to atomic flags 2023-09-15 10:33:48 +01:00
ip6_gre.c net:ipv6: check return value of pskb_trim() 2023-07-19 12:25:58 +01:00
ip6_icmp.c net: icmp: pass zeroed opts from icmp{,v6}_ndo_send before sending 2021-02-23 11:29:52 -08:00
ip6_input.c ipv6: ignore dst hint for multipath routes 2023-09-01 08:11:51 +01:00
ip6_offload.c net: move gso declarations and functions to their own files 2023-06-10 00:11:41 -07:00
ip6_offload.h
ip6_output.c ipv6: avoid atomic fragment on GSO packets 2023-10-25 18:04:29 -07:00
ip6_tunnel.c net: tunnels: annotate lockless accesses to dev->needed_headroom 2023-03-15 00:04:04 -07:00
ip6_udp_tunnel.c ipv6: add new arguments to udp_tunnel6_dst_lookup() 2023-10-23 08:48:57 +01:00
ip6_vti.c ip6_vti: fix slab-use-after-free in decode_session6 2023-07-11 11:06:08 +02:00
ip6mr.c net: ipv4, ipv6: fix IPSTATS_MIB_OUTOCTETS increment duplicated 2023-08-30 09:44:09 +01:00
ipcomp6.c xfrm: ipcomp: add extack to ipcomp{4,6}_init_state 2022-09-29 07:18:00 +02:00
ipv6_sockglue.c ipv6: lockless IPV6_ADDR_PREFERENCES implementation 2023-09-19 18:21:44 +02:00
Kconfig ipv6: fix indentation of a config attribute 2023-08-16 10:03:08 +01:00
Makefile net: ipv6: use ipv6-y directly instead of ipv6-objs 2021-09-28 13:13:40 +01:00
mcast_snoop.c net: bridge: mcast: fix broken length + header check for MRDv6 Adv. 2021-04-27 14:02:06 -07:00
mcast.c net: fix IPSTATS_MIB_OUTPKGS increment in OutForwDatagrams. 2023-10-20 12:01:00 +01:00
mip6.c xfrm: mip6: add extack to mip6_destopt_init_state, mip6_rthdr_init_state 2022-09-29 07:18:01 +02:00
ndisc.c net: fix IPSTATS_MIB_OUTPKGS increment in OutForwDatagrams. 2023-10-20 12:01:00 +01:00
netfilter.c netfilter: Use l3mdev flow key when re-routing mangled packets 2022-05-16 13:03:29 +02:00
output_core.c treewide: use get_random_u32_{above,below}() instead of manual loop 2022-11-18 02:15:22 +01:00
ping.c bpf: Propagate modified uaddrlen from cgroup sockaddr programs 2023-10-11 15:03:40 -07:00
proc.c net: fix IPSTATS_MIB_OUTPKGS increment in OutForwDatagrams. 2023-10-20 12:01:00 +01:00
protocol.c
raw.c net: fix IPSTATS_MIB_OUTPKGS increment in OutForwDatagrams. 2023-10-20 12:01:00 +01:00
reassembly.c networking: Update to register_net_sysctl_sz 2023-08-15 15:26:18 -07:00
route.c ipv6: lockless IPV6_ADDR_PREFERENCES implementation 2023-09-19 18:21:44 +02:00
rpl_iptunnel.c ipv6: rpl: Remove redundant skb_dst_drop(). 2023-07-12 17:12:29 -07:00
rpl.c ipv6: rpl: Remove pskb(_may)?_pull() in ipv6_rpl_srh_rcv(). 2023-06-19 11:32:58 -07:00
seg6_hmac.c net: ipv6: unexport __init-annotated seg6_hmac_net_init() 2022-06-28 21:23:30 -07:00
seg6_iptunnel.c seg6: Cleanup duplicates of skb_dst_drop calls 2023-05-17 09:05:47 +01:00
seg6_local.c seg6: add NEXT-C-SID support for SRv6 End.X behavior 2023-08-15 18:51:47 -07:00
seg6.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2022-09-08 18:38:30 +02:00
sit.c sit: update dev->needed_headroom in ipip6_tunnel_bind_dev() 2023-04-28 09:48:14 +01:00
syncookies.c tcp: Fix data-races around sysctl_tcp_syncookies. 2022-07-18 12:21:54 +01:00
sysctl_net_ipv6.c networking: Update to register_net_sysctl_sz 2023-08-15 15:26:18 -07:00
tcp_ipv6.c ipv6: drop feature RTAX_FEATURE_ALLFRAG 2023-10-25 18:04:29 -07:00
tcpv6_offload.c net: Make gro complete function to return void 2023-05-31 09:50:17 +01:00
tunnel6.c
udp_impl.h tcp/udp: Call inet6_destroy_sock() in IPv6 sk->sk_destruct(). 2022-10-12 17:50:37 -07:00
udp_offload.c net: gro: fix misuse of CB in udp socket lookup 2023-07-29 17:10:27 +01:00
udp.c bpf: Propagate modified uaddrlen from cgroup sockaddr programs 2023-10-11 15:03:40 -07:00
udplite.c udplite: remove UDPLITE_BIT 2023-09-14 16:16:36 +02:00
xfrm6_input.c udp: annotate data-races around udp->encap_type 2023-09-14 16:16:36 +02:00
xfrm6_output.c ipv6: drop feature RTAX_FEATURE_ALLFRAG 2023-10-25 18:04:29 -07:00
xfrm6_policy.c ipsec-2023-10-17 2023-10-17 18:21:13 -07:00
xfrm6_protocol.c
xfrm6_state.c
xfrm6_tunnel.c xfrm: tunnel: add extack to ipip_init_state, xfrm6_tunnel_init_state 2022-09-29 07:18:00 +02:00