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Alex Henrie f4bcbf360a 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 5 seconds or less, after a few minutes with
the preferred lifetime set to 6 seconds, and not at all with the
preferred lifetime set to 7 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 5 or 6 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 setting /proc/sys/net/ipv6/conf/*/regen_min_advance
and /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>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2024-02-15 15:34:40 +01:00
arch Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2024-02-08 15:30:33 -08:00
block block: Fix where bio IO priority gets set 2024-02-01 11:00:06 -07:00
certs This update includes the following changes: 2023-11-02 16:15:30 -10:00
crypto crypto: algif_hash - Remove bogus SGL free on zero-length error path 2024-02-02 18:08:12 +08:00
Documentation net: ipv6/addrconf: clamp preferred_lft to the minimum required 2024-02-15 15:34:40 +01:00
drivers igc: Add support for LEDs on i225/i226 2024-02-15 13:38:59 +01:00
fs eventpoll: Add epoll ioctl for epoll_params 2024-02-14 11:01:01 +00:00
include net: ipv6/addrconf: introduce a regen_min_advance sysctl 2024-02-15 15:34:40 +01:00
init Kconfig: Disable -Wstringop-overflow for GCC globally 2024-02-01 14:57:17 -08:00
io_uring io_uring/net: fix sr->len for IORING_OP_RECV with MSG_WAITALL and buffers 2024-02-01 06:42:36 -07:00
ipc shm: Slim down dependencies 2023-12-20 19:26:31 -05:00
kernel Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2024-02-08 15:30:33 -08:00
lib net: blackhole_dev: fix build warning for ethh set but not used 2024-02-05 12:30:54 +00:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm 22 hotfixes. 11 are cc:stable and the remainder address post-6.7 issues 2024-01-29 17:12:16 -08:00
net net: ipv6/addrconf: clamp preferred_lft to the minimum required 2024-02-15 15:34:40 +01:00
rust rust: phy: use VTABLE_DEFAULT_ERROR 2024-01-27 14:28:00 +00:00
samples samples/cgroup: add .gitignore file for generated samples 2024-01-24 11:52:40 -08:00
scripts Kbuild fixes for v6.8 2024-02-01 11:57:42 -08:00
security Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2024-02-01 15:12:37 -08:00
sound ASoC: Fixes for v6.8 2024-02-01 19:40:42 +01:00
tools selftests/net: Adding test cases of replacing routes and route advertisements. 2024-02-12 10:24:13 +00:00
usr Kbuild updates for v6.8 2024-01-18 17:57:07 -08:00
virt Generic: 2024-01-17 13:03:37 -08:00
.clang-format clang-format: Update with v6.7-rc4's for_each macro list 2023-12-08 23:54:38 +01:00
.cocciconfig
.editorconfig Add .editorconfig file for basic formatting 2023-12-28 16:22:47 +09:00
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore Add .editorconfig file for basic formatting 2023-12-28 16:22:47 +09:00
.mailmap mailmap: add entry for Stefan Wahren 2024-01-31 13:38:51 +00:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING
CREDITS MAINTAINERS: supplement of zswap maintainers update 2024-01-25 23:52:21 -08:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig
MAINTAINERS linux-can-next-for-6.9-20240213 2024-02-14 10:00:35 +00:00
Makefile Linux 6.8-rc3 2024-02-04 12:20:36 +00:00
README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.