Add the mibs required to cover the few possible fallback causes still
lacking suck info.
Move the relevant mib increment into the fallback helper, so that no
eventual future fallback operation will miss a paired mib increment.
Additionally track failed fallback via its own mib, such mib is
incremented only when a fallback mandated by the protocol fails - due to
racing subflow creation.
While at the above, rename an existing helper to reduce long lines
problems all along.
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20250723-net-next-mptcp-track-fallbacks-v1-1-a83cce08f2d5@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
The Fixes commit mentioned this:
> An MPTCP firewall blackhole can be detected if the following SYN
> retransmission after a fallback to "plain" TCP is accepted.
But in fact, this blackhole was detected if any following SYN
retransmissions after a fallback to TCP was accepted.
That's because 'mptcp_subflow_early_fallback()' will set 'request_mptcp'
to 0, and 'mpc_drop' will never be reset to 0 after.
This is an issue, because some not so unusual situations might cause the
kernel to detect a false-positive blackhole, e.g. a client trying to
connect to a server while the network is not ready yet, causing a few
SYN retransmissions, before reaching the end server.
Fixes: 27069e7cb3 ("mptcp: disable active MPTCP in case of blackhole")
Cc: stable@vger.kernel.org
Reviewed-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
The number of SYN + MPC retransmissions before falling back to TCP was
fixed to 2. This is certainly a good default value, but having a fixed
number can be a problem in some environments.
The current behaviour means that if all packets are dropped, there will
be:
- The initial SYN + MPC
- 2 retransmissions with MPC
- The next ones will be without MPTCP.
So typically ~3 seconds before falling back to TCP. In some networks
where some temporally blackholes are unfortunately frequent, or when a
client tries to initiate connections while the network is not ready yet,
this can cause new connections not to have MPTCP connections.
In such environments, it is now possible to increase the number of SYN
retransmissions with MPTCP options to make sure MPTCP is used.
Interesting values are:
- 0: the first retransmission will be done without MPTCP options: quite
aggressive, but also a higher risk of detecting false-positive
MPTCP blackholes.
- >= 128: all SYN retransmissions will keep the MPTCP options: back to
the < 6.12 behaviour.
The default behaviour is not changed here.
Reviewed-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20250117-net-next-mptcp-syn_retrans_before_tcp_fallback-v1-1-ab4b187099b0@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
An MPTCP firewall blackhole can be detected if the following SYN
retransmission after a fallback to "plain" TCP is accepted.
In case of blackhole, a similar technique to the one in place with TFO
is now used: MPTCP can be disabled for a certain period of time, 1h by
default. This time period will grow exponentially when more blackhole
issues get detected right after MPTCP is re-enabled and will reset to
the initial value when the blackhole issue goes away.
The blackhole period can be modified thanks to a new sysctl knob:
blackhole_timeout. Two new MIB counters help understanding what's
happening:
- 'Blackhole', incremented when a blackhole is detected.
- 'MPCapableSYNTXDisabled', incremented when an MPTCP connection
directly falls back to TCP during the blackhole period.
Because the technique is inspired by the one used by TFO, an important
part of the new code is similar to what can find in tcp_fastopen.c, with
some adaptations to the MPTCP case.
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/57
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20240909-net-next-mptcp-fallback-x-mpc-v1-3-da7ebb4cd2a3@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
const qualify the struct ctl_table argument in the proc_handler function
signatures. This is a prerequisite to moving the static ctl_table
structs into .rodata data which will ensure that proc_handler function
pointers cannot be modified.
This patch has been generated by the following coccinelle script:
```
virtual patch
@r1@
identifier ctl, write, buffer, lenp, ppos;
identifier func !~ "appldata_(timer|interval)_handler|sched_(rt|rr)_handler|rds_tcp_skbuf_handler|proc_sctp_do_(hmac_alg|rto_min|rto_max|udp_port|alpha_beta|auth|probe_interval)";
@@
int func(
- struct ctl_table *ctl
+ const struct ctl_table *ctl
,int write, void *buffer, size_t *lenp, loff_t *ppos);
@r2@
identifier func, ctl, write, buffer, lenp, ppos;
@@
int func(
- struct ctl_table *ctl
+ const struct ctl_table *ctl
,int write, void *buffer, size_t *lenp, loff_t *ppos)
{ ... }
@r3@
identifier func;
@@
int func(
- struct ctl_table *
+ const struct ctl_table *
,int , void *, size_t *, loff_t *);
@r4@
identifier func, ctl;
@@
int func(
- struct ctl_table *ctl
+ const struct ctl_table *ctl
,int , void *, size_t *, loff_t *);
@r5@
identifier func, write, buffer, lenp, ppos;
@@
int func(
- struct ctl_table *
+ const struct ctl_table *
,int write, void *buffer, size_t *lenp, loff_t *ppos);
```
* Code formatting was adjusted in xfs_sysctl.c to comply with code
conventions. The xfs_stats_clear_proc_handler,
xfs_panic_mask_proc_handler and xfs_deprecated_dointvec_minmax where
adjusted.
* The ctl_table argument in proc_watchdog_common was const qualified.
This is called from a proc_handler itself and is calling back into
another proc_handler, making it necessary to change it as part of the
proc_handler migration.
Co-developed-by: Thomas Weißschuh <linux@weissschuh.net>
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Co-developed-by: Joel Granados <j.granados@samsung.com>
Signed-off-by: Joel Granados <j.granados@samsung.com>
Cross-merge networking fixes after downstream PR.
No conflicts.
Adjacent changes:
drivers/net/ethernet/hisilicon/hns3/hns3pf/hclge_main.c
35d92abfba ("net: hns3: fix kernel crash when devlink reload during initialization")
2a1a1a7b5f ("net: hns3: add command queue trace for hns3")
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit comes at the tail end of a greater effort to remove the
empty elements at the end of the ctl_table arrays (sentinels) which
will reduce the overall build time size of the kernel and run time
memory bloat by ~64 bytes per sentinel (further information Link :
https://lore.kernel.org/all/ZO5Yx5JFogGi%2FcBo@bombadil.infradead.org/)
To avoid lots of small commits, this commit brings together network
changes from (as they appear in MAINTAINERS) LLC, MPTCP, NETROM NETWORK
LAYER, PHONET PROTOCOL, ROSE NETWORK LAYER, RXRPC SOCKETS, SCTP
PROTOCOL, SHARED MEMORY COMMUNICATIONS (SMC), TIPC NETWORK LAYER and
NETWORKING [IPSEC]
* Remove sentinel element from ctl_table structs.
* Replace empty array registration with the register_net_sysctl_sz call
in llc_sysctl_init
* Replace the for loop stop condition that tests for procname == NULL
with one that depends on array size in sctp_sysctl_net_register
* Remove instances where an array element is zeroed out to make it look
like a sentinel in xfrm_sysctl_init. This is not longer needed and is
safe after commit c899710fe7 ("networking: Update to
register_net_sysctl_sz") added the array size to the ctl_table
registration
* Use a table_size variable to keep the value of ARRAY_SIZE
Signed-off-by: Joel Granados <j.granados@samsung.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
To be able to constify instances of struct ctl_tables it is necessary to
remove ways through which non-const versions are exposed from the
sysctl core.
One of these is the ctl_table_arg member of struct ctl_table_header.
Constify this reference as a prerequisite for the full constification of
struct ctl_table instances.
No functional change.
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
The MPTCP protocol allows sockets with no alive subflows to stay
in ESTABLISHED status for and user-defined timeout, to allow for
later subflows creation.
Currently such timeout is constant - TCP_TIMEWAIT_LEN. Let the
user-space configure them via a newly added sysctl, to better cope
with busy servers and simplify (make them faster) the relevant
pktdrill tests.
Note that the new know does not apply to orphaned MPTCP socket
waiting for the data_fin handshake completion: they always wait
TCP_TIMEWAIT_LEN.
Reviewed-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Mat Martineau <martineau@kernel.org>
Link: https://lore.kernel.org/r/20231023-send-net-next-20231023-2-v1-1-9dc60939d371@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Pull sysctl updates from Luis Chamberlain:
"Long ago we set out to remove the kitchen sink on kernel/sysctl.c
arrays and placings sysctls to their own sybsystem or file to help
avoid merge conflicts. Matthew Wilcox pointed out though that if we're
going to do that we might as well also *save* space while at it and
try to remove the extra last sysctl entry added at the end of each
array, a sentintel, instead of bloating the kernel by adding a new
sentinel with each array moved.
Doing that was not so trivial, and has required slowing down the moves
of kernel/sysctl.c arrays and measuring the impact on size by each new
move.
The complex part of the effort to help reduce the size of each sysctl
is being done by the patient work of el señor Don Joel Granados. A lot
of this is truly painful code refactoring and testing and then trying
to measure the savings of each move and removing the sentinels.
Although Joel already has code which does most of this work,
experience with sysctl moves in the past shows is we need to be
careful due to the slew of odd build failures that are possible due to
the amount of random Kconfig options sysctls use.
To that end Joel's work is split by first addressing the major
housekeeping needed to remove the sentinels, which is part of this
merge request. The rest of the work to actually remove the sentinels
will be done later in future kernel releases.
The preliminary math is showing this will all help reduce the overall
build time size of the kernel and run time memory consumed by the
kernel by about ~64 bytes per array where we are able to remove each
sentinel in the future. That also means there is no more bloating the
kernel with the extra ~64 bytes per array moved as no new sentinels
are created"
* tag 'sysctl-6.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux:
sysctl: Use ctl_table_size as stopping criteria for list macro
sysctl: SIZE_MAX->ARRAY_SIZE in register_net_sysctl
vrf: Update to register_net_sysctl_sz
networking: Update to register_net_sysctl_sz
netfilter: Update to register_net_sysctl_sz
ax.25: Update to register_net_sysctl_sz
sysctl: Add size to register_net_sysctl function
sysctl: Add size arg to __register_sysctl_init
sysctl: Add size to register_sysctl
sysctl: Add a size arg to __register_sysctl_table
sysctl: Add size argument to init_header
sysctl: Add ctl_table_size to ctl_table_header
sysctl: Use ctl_table_header in list_for_each_table_entry
sysctl: Prefer ctl_table_header in proc_sysctl
