xdp_update_skb_shared_info() needs to update skb state which
was maintained in xdp_buff / frame. Pass full flags into it,
instead of breaking it out bit by bit. We will need to add
a bit for unreadable frags (even tho XDP doesn't support
those the driver paths may be common), at which point almost
all call sites would become:
xdp_update_skb_shared_info(skb, num_frags,
sinfo->xdp_frags_size,
MY_PAGE_SIZE * num_frags,
xdp_buff_is_frag_pfmemalloc(xdp),
xdp_buff_is_frag_unreadable(xdp));
Keep a helper for accessing the flags, in case we need to
transform them somehow in the future (e.g. to cover up xdp_buff
vs xdp_frame differences).
While we are touching call callers - rename the helper to
xdp_update_skb_frags_info(), previous name may have implied that
it's shinfo that's updated. We are updating flags in struct sk_buff
based on frags that got attched.
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Acked-by: Jesper Dangaard Brouer <hawk@kernel.org>
Link: https://patch.msgid.link/20250905221539.2930285-2-kuba@kernel.org
Acked-by: Stanislav Fomichev <sdf@fomichev.me>
Reviewed-by: Alexander Lobakin <aleksander.lobakin@intel.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Cross-merge networking fixes after downstream PR (net-6.17-rc4).
No conflicts.
Adjacent changes:
drivers/net/ethernet/intel/idpf/idpf_txrx.c
02614eee26 ("idpf: do not linearize big TSO packets")
6c4e684802 ("idpf: remove obsolete stashing code")
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Multi-PF netdevs have queues belonging to different PFs which also means
different DMA devices. This means that the binding on the DMA buffer can
be done to the incorrect device.
This change allows devmem binding to multiple queues only when the
queues have the same DMA device. Otherwise an error is returned.
Signed-off-by: Dragos Tatulea <dtatulea@nvidia.com>
Link: https://patch.msgid.link/20250827144017.1529208-9-dtatulea@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Instead of reading the requested rx queues after binding the buffer,
read the rx queues in advance in a bitmap and iterate over them when
needed.
This is a preparation for fetching the DMA device for each queue.
This patch has no functional changes besides adding an extra
rq index bounds check.
Signed-off-by: Dragos Tatulea <dtatulea@nvidia.com>
Reviewed-by: Mina Almasry <almasrymina@google.com>
Link: https://patch.msgid.link/20250827144017.1529208-8-dtatulea@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Switch to the new API for fetching DMA devices for a netdev. The API is
called with queue index 0 for now which is equivalent with the previous
behavior.
This patch will allow devmem to work with devices where the DMA device
is not stored in the parent device. mlx5 SFs are an example of such a
device.
Multi-PF netdevs are still problematic (as they were before this
change). Upcoming patches will address this for the rx binding.
Signed-off-by: Dragos Tatulea <dtatulea@nvidia.com>
Reviewed-by: Mina Almasry <almasrymina@google.com>
Link: https://patch.msgid.link/20250827144017.1529208-5-dtatulea@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
For zerocopy (io_uring, devmem), there is an assumption that the
parent device can do DMA. However that is not always the case:
- Scalable Function netdevs [1] have the DMA device in the grandparent.
- For Multi-PF netdevs [2] queues can be associated to different DMA
devices.
This patch introduces the a queue based interface for allowing drivers
to expose a different DMA device for zerocopy.
[1] Documentation/networking/device_drivers/ethernet/mellanox/mlx5/switchdev.rst
[2] Documentation/networking/multi-pf-netdev.rst
Signed-off-by: Dragos Tatulea <dtatulea@nvidia.com>
Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>
Reviewed-by: Mina Almasry <almasrymina@google.com>
Link: https://patch.msgid.link/20250827144017.1529208-3-dtatulea@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This patch fixes an issue where two different flows on the same RXq
produce the same hash resulting in continuous flow overwrites.
Flow #1: A packet for Flow #1 comes in, kernel calls the steering
function. The driver gives back a filter id. The kernel saves
this filter id in the selected slot. Later, the driver's
service task checks if any filters have expired and then
installs the rule for Flow #1.
Flow #2: A packet for Flow #2 comes in. It goes through the same steps.
But this time, the chosen slot is being used by Flow #1. The
driver gives a new filter id and the kernel saves it in the
same slot. When the driver's service task runs, it runs through
all the flows, checks if Flow #1 should be expired, the kernel
returns True as the slot has a different filter id, and then
the driver installs the rule for Flow #2.
Flow #1: Another packet for Flow #1 comes in. The same thing repeats.
The slot is overwritten with a new filter id for Flow #1.
This causes a repeated cycle of flow programming for missed packets,
wasting CPU cycles while not improving performance. This problem happens
at higher rates when the RPS table is small, but tests show it still
happens even with 12,000 connections and an RPS size of 16K per queue
(global table size = 144x16K = 64K).
This patch prevents overwriting an rps_dev_flow entry if it is active.
The intention is that it is better to do aRFS for the first flow instead
of hurting all flows on the same hash. Without this, two (or more) flows
on one RX queue with the same hash can keep overwriting each other. This
causes the driver to reprogram the flow repeatedly.
Changes:
1. Add a new 'hash' field to struct rps_dev_flow.
2. Add rps_flow_is_active(): a helper function to check if a flow is
active or not, extracted from rps_may_expire_flow(). It is further
simplified as per reviewer feedback.
3. In set_rps_cpu():
- Avoid overwriting by programming a new filter if:
- The slot is not in use, or
- The slot is in use but the flow is not active, or
- The slot has an active flow with the same hash, but target CPU
differs.
- Save the hash in the rps_dev_flow entry.
4. rps_may_expire_flow(): Use earlier extracted rps_flow_is_active().
Testing & results:
- Driver: ice (E810 NIC), Kernel: net-next
- #CPUs = #RXq = 144 (1:1)
- Number of flows: 12K
- Eight RPS settings from 256 to 32768. Though RPS=256 is not ideal,
it is still sufficient to cover 12K flows (256*144 rx-queues = 64K
global table slots)
- Global Table Size = 144 * RPS (effectively equal to 256 * RPS)
- Each RPS test duration = 8 mins (org code) + 8 mins (new code).
- Metrics captured on client
Legend for following tables:
Steer-C: #times ndo_rx_flow_steer() was Called by set_rps_cpu()
Steer-L: #times ice_arfs_flow_steer() Looped over aRFS entries
Add: #times driver actually programmed aRFS (ice_arfs_build_entry())
Del: #times driver deleted the flow (ice_arfs_del_flow_rules())
Units: K = 1,000 times, M = 1 million times
|-------|---------|------| Org Code |---------|---------|
| RPS | Latency | CPU | Add | Del | Steer-C | Steer-L |
|-------|---------|------|--------|--------|---------|---------|
| 256 | 227.0 | 93.2 | 1.6M | 1.6M | 121.7M | 267.6M |
| 512 | 225.9 | 94.1 | 11.5M | 11.2M | 65.7M | 199.6M |
| 1024 | 223.5 | 95.6 | 16.5M | 16.5M | 27.1M | 187.3M |
| 2048 | 222.2 | 96.3 | 10.5M | 10.5M | 12.5M | 115.2M |
| 4096 | 223.9 | 94.1 | 5.5M | 5.5M | 7.2M | 65.9M |
| 8192 | 224.7 | 92.5 | 2.7M | 2.7M | 3.0M | 29.9M |
| 16384 | 223.5 | 92.5 | 1.3M | 1.3M | 1.4M | 13.9M |
| 32768 | 219.6 | 93.2 | 838.1K | 838.1K | 965.1K | 8.9M |
|-------|---------|------| New Code |---------|---------|
| 256 | 201.5 | 99.1 | 13.4K | 5.0K | 13.7K | 75.2K |
| 512 | 202.5 | 98.2 | 11.2K | 5.9K | 11.2K | 55.5K |
| 1024 | 207.3 | 93.9 | 11.5K | 9.7K | 11.5K | 59.6K |
| 2048 | 207.5 | 96.7 | 11.8K | 11.1K | 15.5K | 79.3K |
| 4096 | 206.9 | 96.6 | 11.8K | 11.7K | 11.8K | 63.2K |
| 8192 | 205.8 | 96.7 | 11.9K | 11.8K | 11.9K | 63.9K |
| 16384 | 200.9 | 98.2 | 11.9K | 11.9K | 11.9K | 64.2K |
| 32768 | 202.5 | 98.0 | 11.9K | 11.9K | 11.9K | 64.2K |
|-------|---------|------|--------|--------|---------|---------|
Some observations:
1. Overall Latency improved: (1790.19-1634.94)/1790.19*100 = 8.67%
2. Overall CPU increased: (777.32-751.49)/751.45*100 = 3.44%
3. Flow Management (add/delete) remained almost constant at ~11K
compared to values in millions.
Signed-off-by: Krishna Kumar <krikku@gmail.com>
Link: https://patch.msgid.link/20250825031005.3674864-2-krikku@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Convert the ->flowic_tos field of struct flowi_common from __u8 to
dscp_t, rename it ->flowic_dscp and propagate these changes to struct
flowi and struct flowi4.
We've had several bugs in the past where ECN bits could interfere with
IPv4 routing, because these bits were not properly cleared when setting
->flowi4_tos. These bugs should be fixed now and the dscp_t type has
been introduced to ensure that variables carrying DSCP values don't
accidentally have any ECN bits set. Several variables and structure
fields have been converted to dscp_t already, but the main IPv4 routing
structure, struct flowi4, is still using a __u8. To avoid any future
regression, this patch converts it to dscp_t.
There are many users to convert at once. Fortunately, around half of
->flowi4_tos users already have a dscp_t value at hand, which they
currently convert to __u8 using inet_dscp_to_dsfield(). For all of
these users, we just need to drop that conversion.
But, although we try to do the __u8 <-> dscp_t conversions at the
boundaries of the network or of user space, some places still store
TOS/DSCP variables as __u8 in core networking code. Those can hardly be
converted either because the data structure is part of UAPI or because
the same variable or field is also used for handling ECN in other parts
of the code. In all of these cases where we don't have a dscp_t
variable at hand, we need to use inet_dsfield_to_dscp() when
interacting with ->flowi4_dscp.
Changes since v1:
* Fix space alignment in __bpf_redirect_neigh_v4() (Ido).
Signed-off-by: Guillaume Nault <gnault@redhat.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Link: https://patch.msgid.link/29acecb45e911d17446b9a3dbdb1ab7b821ea371.1756128932.git.gnault@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
These socket lookup functions required struct inet_hashinfo because
they are shared by TCP and DCCP.
* __inet_lookup_established()
* __inet_lookup_listener()
* __inet6_lookup_established()
* inet6_lookup_listener()
DCCP has gone, and we don't need to pass hashinfo down to them.
Let's fetch net->ipv4.tcp_death_row.hashinfo directly in the above
4 functions.
Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20250822190803.540788-5-kuniyu@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Martin KaFai Lau says:
====================
pull-request: bpf-next 2025-08-21
We've added 9 non-merge commits during the last 3 day(s) which contain
a total of 13 files changed, 1027 insertions(+), 27 deletions(-).
The main changes are:
1) Added bpf dynptr support for accessing the metadata of a skb,
from Jakub Sitnicki.
The patches are merged from a stable branch bpf-next/skb-meta-dynptr.
The same patches have also been merged into bpf-next/master.
* tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next:
selftests/bpf: Cover metadata access from a modified skb clone
selftests/bpf: Cover read/write to skb metadata at an offset
selftests/bpf: Cover write access to skb metadata via dynptr
selftests/bpf: Cover read access to skb metadata via dynptr
selftests/bpf: Parametrize test_xdp_context_tuntap
selftests/bpf: Pass just bpf_map to xdp_context_test helper
selftests/bpf: Cover verifier checks for skb_meta dynptr type
bpf: Enable read/write access to skb metadata through a dynptr
bpf: Add dynptr type for skb metadata
====================
Link: https://patch.msgid.link/20250821191827.2099022-1-martin.lau@linux.dev
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
If *len is equal to 0 at the beginning of __splice_segment
it returns true directly. But when decreasing *len from
a positive number to 0 in __splice_segment, it returns false.
The __skb_splice_bits needs to call __splice_segment again.
Recheck *len if it changes, return true in time.
Reduce unnecessary calls to __splice_segment.
Signed-off-by: Pengtao He <hept.hept.hept@gmail.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://patch.msgid.link/20250819021551.8361-1-hept.hept.hept@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
In __sk_mem_raise_allocated(), charged is initialised as true due
to the weird condition removed in the previous patch.
It makes the variable unreliable by itself, so we have to check
another variable, memcg, in advance.
Also, we will factorise the common check below for memcg later.
if (mem_cgroup_sockets_enabled && sk->sk_memcg)
As a prep, let's initialise charged as false and memcg as NULL.
Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Shakeel Butt <shakeel.butt@linux.dev>
Link: https://patch.msgid.link/20250815201712.1745332-6-kuniyu@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Initially, trace_sock_exceed_buf_limit() was invoked when
__sk_mem_raise_allocated() failed due to the memcg limit or the
global limit.
However, commit d6f19938eb ("net: expose sk wmem in
sock_exceed_buf_limit tracepoint") somehow suppressed the event
only when memcg failed to charge for SK_MEM_RECV, although the
memcg failure for SK_MEM_SEND still triggers the event.
Let's restore the event for SK_MEM_RECV.
Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Shakeel Butt <shakeel.butt@linux.dev>
Link: https://patch.msgid.link/20250815201712.1745332-5-kuniyu@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
When performing Generic Segmentation Offload (GSO) on an IPv6 packet that
contains extension headers, the kernel incorrectly requests checksum offload
if the egress device only advertises NETIF_F_IPV6_CSUM feature, which has
a strict contract: it supports checksum offload only for plain TCP or UDP
over IPv6 and explicitly does not support packets with extension headers.
The current GSO logic violates this contract by failing to disable the feature
for packets with extension headers, such as those used in GREoIPv6 tunnels.
This violation results in the device being asked to perform an operation
it cannot support, leading to a `skb_warn_bad_offload` warning and a collapse
of network throughput. While device TSO/USO is correctly bypassed in favor
of software GSO for these packets, the GSO stack must be explicitly told not
to request checksum offload.
Mask NETIF_F_IPV6_CSUM, NETIF_F_TSO6 and NETIF_F_GSO_UDP_L4
in gso_features_check if the IPv6 header contains extension headers to compute
checksum in software.
The exception is a BIG TCP extension, which, as stated in commit
68e068cabd ("net: reenable NETIF_F_IPV6_CSUM offload for BIG TCP packets"):
"The feature is only enabled on devices that support BIG TCP TSO.
The header is only present for PF_PACKET taps like tcpdump,
and not transmitted by physical devices."
kernel log output (truncated):
WARNING: CPU: 1 PID: 5273 at net/core/dev.c:3535 skb_warn_bad_offload+0x81/0x140
...
Call Trace:
<TASK>
skb_checksum_help+0x12a/0x1f0
validate_xmit_skb+0x1a3/0x2d0
validate_xmit_skb_list+0x4f/0x80
sch_direct_xmit+0x1a2/0x380
__dev_xmit_skb+0x242/0x670
__dev_queue_xmit+0x3fc/0x7f0
ip6_finish_output2+0x25e/0x5d0
ip6_finish_output+0x1fc/0x3f0
ip6_tnl_xmit+0x608/0xc00 [ip6_tunnel]
ip6gre_tunnel_xmit+0x1c0/0x390 [ip6_gre]
dev_hard_start_xmit+0x63/0x1c0
__dev_queue_xmit+0x6d0/0x7f0
ip6_finish_output2+0x214/0x5d0
ip6_finish_output+0x1fc/0x3f0
ip6_xmit+0x2ca/0x6f0
ip6_finish_output+0x1fc/0x3f0
ip6_xmit+0x2ca/0x6f0
inet6_csk_xmit+0xeb/0x150
__tcp_transmit_skb+0x555/0xa80
tcp_write_xmit+0x32a/0xe90
tcp_sendmsg_locked+0x437/0x1110
tcp_sendmsg+0x2f/0x50
...
skb linear: 00000000: e4 3d 1a 7d ec 30 e4 3d 1a 7e 5d 90 86 dd 60 0e
skb linear: 00000010: 00 0a 1b 34 3c 40 20 11 00 00 00 00 00 00 00 00
skb linear: 00000020: 00 00 00 00 00 12 20 11 00 00 00 00 00 00 00 00
skb linear: 00000030: 00 00 00 00 00 11 2f 00 04 01 04 01 01 00 00 00
skb linear: 00000040: 86 dd 60 0e 00 0a 1b 00 06 40 20 23 00 00 00 00
skb linear: 00000050: 00 00 00 00 00 00 00 00 00 12 20 23 00 00 00 00
skb linear: 00000060: 00 00 00 00 00 00 00 00 00 11 bf 96 14 51 13 f9
skb linear: 00000070: ae 27 a0 a8 2b e3 80 18 00 40 5b 6f 00 00 01 01
skb linear: 00000080: 08 0a 42 d4 50 d5 4b 70 f8 1a
Fixes: 04c20a9356 ("net: skip offload for NETIF_F_IPV6_CSUM if ipv6 header contains extension")
Reported-by: Tianhao Zhao <tizhao@redhat.com>
Suggested-by: Michal Schmidt <mschmidt@redhat.com>
Suggested-by: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
Signed-off-by: Jakub Ramaseuski <jramaseu@redhat.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://patch.msgid.link/20250814105119.1525687-1-jramaseu@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Now that we can create a dynptr to skb metadata, make reads to the metadata
area possible with bpf_dynptr_read() or through a bpf_dynptr_slice(), and
make writes to the metadata area possible with bpf_dynptr_write() or
through a bpf_dynptr_slice_rdwr().
Note that for cloned skbs which share data with the original, we limit the
skb metadata dynptr to be read-only since we don't unclone on a
bpf_dynptr_write to metadata.
Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://patch.msgid.link/20250814-skb-metadata-thru-dynptr-v7-2-8a39e636e0fb@cloudflare.com
Add a dynptr type, similar to skb dynptr, but for the skb metadata access.
The dynptr provides an alternative to __sk_buff->data_meta for accessing
the custom metadata area allocated using the bpf_xdp_adjust_meta() helper.
More importantly, it abstracts away the fact where the storage for the
custom metadata lives, which opens up the way to persist the metadata by
relocating it as the skb travels through the network stack layers.
Writes to skb metadata invalidate any existing skb payload and metadata
slices. While this is more restrictive that needed at the moment, it leaves
the door open to reallocating the metadata on writes, and should be only a
minor inconvenience to the users.
Only the program types which can access __sk_buff->data_meta today are
allowed to create a dynptr for skb metadata at the moment. We need to
modify the network stack to persist the metadata across layers before
opening up access to other BPF hooks.
Once more BPF hooks gain access to skb_meta dynptr, we will also need to
add a read-only variant of the helper similar to
bpf_dynptr_from_skb_rdonly.
skb_meta dynptr ops are stubbed out and implemented by subsequent changes.
Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Reviewed-by: Jesse Brandeburg <jbrandeburg@cloudflare.com>
Link: https://patch.msgid.link/20250814-skb-metadata-thru-dynptr-v7-1-8a39e636e0fb@cloudflare.com
The following order of calls currently deadlocks if:
- device has threaded=1; and
- NAPI has persistent config with threaded=0.
netif_napi_add_weight_config()
dev->threaded == 1
napi_kthread_create()
napi_enable()
napi_restore_config()
napi_set_threaded(0)
napi_stop_kthread()
while (NAPIF_STATE_SCHED)
msleep(20)
We deadlock because disabled NAPI has STATE_SCHED set.
Creating a thread in netif_napi_add() just to destroy it in
napi_disable() is fairly ugly in the first place. Let's read
both the device config and the NAPI config in netif_napi_add().
Fixes: e6d7626881 ("net: Update threaded state in napi config in netif_set_threaded")
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Joe Damato <joe@dama.to>
Link: https://patch.msgid.link/20250809001205.1147153-4-kuba@kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
We have to make sure that all future NAPIs will have the right threaded
state when the state is configured on the device level.
We chose not to have an "unset" state for threaded, and not to wipe
the NAPI config clean when channels are explicitly disabled.
This means the persistent config structs "exist" even when their NAPIs
are not instantiated.
Differently put - the NAPI persistent state lives in the net_device
(ncfg == struct napi_config):
,--- [napi 0] - [napi 1]
[dev] | |
`--- [ncfg 0] - [ncfg 1]
so say we a device with 2 queues but only 1 enabled:
,--- [napi 0]
[dev] |
`--- [ncfg 0] - [ncfg 1]
now we set the device to threaded=1:
,---------- [napi 0 (thr:1)]
[dev(thr:1)] |
`---------- [ncfg 0 (thr:1)] - [ncfg 1 (thr:?)]
Since [ncfg 1] was not attached to a NAPI during configuration we
skipped it. If we create a NAPI for it later it will have the old
setting (presumably disabled). One could argue if this is right
or not "in principle", but it's definitely not how things worked
before per-NAPI config..
Fixes: 2677010e77 ("Add support to set NAPI threaded for individual NAPI")
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Joe Damato <joe@dama.to>
Link: https://patch.msgid.link/20250809001205.1147153-3-kuba@kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Page pool can have pages "directly" (locklessly) recycled to it,
if the NAPI that owns the page pool is scheduled to run on the same CPU.
To make this safe we check that the NAPI is disabled while we destroy
the page pool. In most cases NAPI and page pool lifetimes are tied
together so this happens naturally.
The queue API expects the following order of calls:
-> mem_alloc
alloc new pp
-> stop
napi_disable
-> start
napi_enable
-> mem_free
free old pp
Here we allocate the page pool in ->mem_alloc and free in ->mem_free.
But the NAPIs are only stopped between ->stop and ->start. We created
page_pool_disable_direct_recycling() to safely shut down the recycling
in ->stop. This way the page_pool_destroy() call in ->mem_free doesn't
have to worry about recycling any more.
Unfortunately, the page_pool_disable_direct_recycling() is not enough
to deal with failures which necessitate freeing the _new_ page pool.
If we hit a failure in ->mem_alloc or ->stop the new page pool has
to be freed while the NAPI is active (assuming driver attaches the
page pool to an existing NAPI instance and doesn't reallocate NAPIs).
Freeing the new page pool is technically safe because it hasn't been
used for any packets, yet, so there can be no recycling. But the check
in napi_assert_will_not_race() has no way of knowing that. We could
check if page pool is empty but that'd make the check much less likely
to trigger during development.
Add page_pool_enable_direct_recycling(), pairing with
page_pool_disable_direct_recycling(). It will allow us to create the new
page pools in "disabled" state and only enable recycling when we know
the reconfig operation will not fail.
Coincidentally it will also let us re-enable the recycling for the old
pool, if the reconfig failed:
-> mem_alloc (new)
-> stop (old)
# disables direct recycling for old
-> start (new)
# fail!!
-> start (old)
# go back to old pp but direct recycling is lost :(
-> mem_free (new)
The new helper is idempotent to make the life easier for drivers,
which can operate in HDS mode and support zero-copy Rx.
The driver can call the helper twice whether there are two pools
or it has multiple references to a single pool.
Fixes: 40eca00ae6 ("bnxt_en: unlink page pool when stopping Rx queue")
Tested-by: David Wei <dw@davidwei.uk>
Link: https://patch.msgid.link/20250805003654.2944974-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Pull networking fixes from Jakub Kicinski:
Previous releases - regressions:
- netlink: avoid infinite retry looping in netlink_unicast()
Previous releases - always broken:
- packet: fix a race in packet_set_ring() and packet_notifier()
- ipv6: reject malicious packets in ipv6_gso_segment()
- sched: mqprio: fix stack out-of-bounds write in tc entry parsing
- net: drop UFO packets (injected via virtio) in udp_rcv_segment()
- eth: mlx5: correctly set gso_segs when LRO is used, avoid false
positive checksum validation errors
- netpoll: prevent hanging NAPI when netcons gets enabled
- phy: mscc: fix parsing of unicast frames for PTP timestamping
- a number of device tree / OF reference leak fixes"
* tag 'net-6.17-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (44 commits)
pptp: fix pptp_xmit() error path
net: ti: icssg-prueth: Fix skb handling for XDP_PASS
net: Update threaded state in napi config in netif_set_threaded
selftests: netdevsim: Xfail nexthop test on slow machines
eth: fbnic: Lock the tx_dropped update
eth: fbnic: Fix tx_dropped reporting
eth: fbnic: remove the debugging trick of super high page bias
net: ftgmac100: fix potential NULL pointer access in ftgmac100_phy_disconnect
dt-bindings: net: Replace bouncing Alexandru Tachici emails
dpll: zl3073x: ZL3073X_I2C and ZL3073X_SPI should depend on NET
net/sched: mqprio: fix stack out-of-bounds write in tc entry parsing
Revert "net: mdio_bus: Use devm for getting reset GPIO"
selftests: net: packetdrill: xfail all problems on slow machines
net/packet: fix a race in packet_set_ring() and packet_notifier()
benet: fix BUG when creating VFs
net: airoha: npu: Add missing MODULE_FIRMWARE macros
net: devmem: fix DMA direction on unmapping
ipa: fix compile-testing with qcom-mdt=m
eth: fbnic: unlink NAPIs from queues on error to open
net: Add locking to protect skb->dev access in ip_output
...
Commit 2677010e77 ("Add support to set NAPI threaded for individual
NAPI") added support to enable/disable threaded napi using netlink. This
also extended the napi config save/restore functionality to set the napi
threaded state. This breaks netdev reset for drivers that use napi
threaded at device level and also use napi config save/restore on
napi_disable/napi_enable. Basically on netdev with napi threaded enabled
at device level, a napi_enable call will get stuck trying to stop the
napi kthread. This is because the napi->config->threaded is set to
disabled when threaded is enabled at device level.
The issue can be reproduced on virtio-net device using qemu. To
reproduce the issue run following,
echo 1 > /sys/class/net/threaded
ethtool -L eth0 combined 1
Update the threaded state in napi config in netif_set_threaded and add a
new test that verifies this scenario.
Tested on qemu with virtio-net:
NETIF=eth0 ./tools/testing/selftests/drivers/net/napi_threaded.py
TAP version 13
1..2
ok 1 napi_threaded.change_num_queues
ok 2 napi_threaded.enable_dev_threaded_disable_napi_threaded
# Totals: pass:2 fail:0 xfail:0 xpass:0 skip:0 error:0
Fixes: 2677010e77 ("Add support to set NAPI threaded for individual NAPI")
Signed-off-by: Samiullah Khawaja <skhawaja@google.com>
Link: https://patch.msgid.link/20250804164457.2494390-1-skhawaja@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Paolo spotted hangs in NIPA running driver tests against virtio.
The tests hang in virtnet_close() -> virtnet_napi_tx_disable().
The problem is only reproducible if running multiple of our tests
in sequence (I used TEST_PROGS="xdp.py ping.py netcons_basic.sh \
netpoll_basic.py stats.py"). Initial suspicion was that this is
a simple case of double-disable of NAPI, but instrumenting the
code reveals:
Deadlocked on NAPI ffff888007cd82c0 (virtnet_poll_tx):
state: 0x37, disabled: false, owner: 0, listed: false, weight: 64
The NAPI was not in fact disabled, owner is 0 (rather than -1),
so the NAPI "thinks" it's scheduled for CPU 0 but it's not listed
(!list_empty(&n->poll_list) => false). It seems odd that normal NAPI
processing would wedge itself like this.
Better suspicion is that netpoll gets enabled while NAPI is polling,
and also grabs the NAPI instance. This confuses napi_complete_done():
[netpoll] [normal NAPI]
napi_poll()
have = netpoll_poll_lock()
rcu_access_pointer(dev->npinfo)
return NULL # no netpoll
__napi_poll()
->poll(->weight)
poll_napi()
cmpxchg(->poll_owner, -1, cpu)
poll_one_napi()
set_bit(NAPI_STATE_NPSVC, ->state)
napi_complete_done()
if (NAPIF_STATE_NPSVC)
return false
# exit without clearing SCHED
This feels very unlikely, but perhaps virtio has some interactions
with the hypervisor in the NAPI ->poll that makes the race window
larger?
Best I could to to prove the theory was to add and trigger this
warning in napi_poll (just before netpoll_poll_unlock()):
WARN_ONCE(!have && rcu_access_pointer(n->dev->npinfo) &&
napi_is_scheduled(n) && list_empty(&n->poll_list),
"NAPI race with netpoll %px", n);
If this warning hits the next virtio_close() will hang.
This patch survived 30 test iterations without a hang (without it
the longest clean run was around 10). Credit for triggering this
goes to Breno's recent netconsole tests.
Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Reported-by: Paolo Abeni <pabeni@redhat.com>
Link: https://lore.kernel.org/c5a93ed1-9abe-4880-a3bb-8d1678018b1d@redhat.com
Acked-by: Jason Wang <jasowang@redhat.com>
Reviewed-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Link: https://patch.msgid.link/20250726010846.1105875-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Pull bpf updates from Alexei Starovoitov:
- Remove usermode driver (UMD) framework (Thomas Weißschuh)
- Introduce Strongly Connected Component (SCC) in the verifier to
detect loops and refine register liveness (Eduard Zingerman)
- Allow 'void *' cast using bpf_rdonly_cast() and corresponding
'__arg_untrusted' for global function parameters (Eduard Zingerman)
- Improve precision for BPF_ADD and BPF_SUB operations in the verifier
(Harishankar Vishwanathan)
- Teach the verifier that constant pointer to a map cannot be NULL
(Ihor Solodrai)
- Introduce BPF streams for error reporting of various conditions
detected by BPF runtime (Kumar Kartikeya Dwivedi)
- Teach the verifier to insert runtime speculation barrier (lfence on
x86) to mitigate speculative execution instead of rejecting the
programs (Luis Gerhorst)
- Various improvements for 'veristat' (Mykyta Yatsenko)
- For CONFIG_DEBUG_KERNEL config warn on internal verifier errors to
improve bug detection by syzbot (Paul Chaignon)
- Support BPF private stack on arm64 (Puranjay Mohan)
- Introduce bpf_cgroup_read_xattr() kfunc to read xattr of cgroup's
node (Song Liu)
- Introduce kfuncs for read-only string opreations (Viktor Malik)
- Implement show_fdinfo() for bpf_links (Tao Chen)
- Reduce verifier's stack consumption (Yonghong Song)
- Implement mprog API for cgroup-bpf programs (Yonghong Song)
* tag 'bpf-next-6.17' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (192 commits)
selftests/bpf: Migrate fexit_noreturns case into tracing_failure test suite
selftests/bpf: Add selftest for attaching tracing programs to functions in deny list
bpf: Add log for attaching tracing programs to functions in deny list
bpf: Show precise rejected function when attaching fexit/fmod_ret to __noreturn functions
bpf: Fix various typos in verifier.c comments
bpf: Add third round of bounds deduction
selftests/bpf: Test invariants on JSLT crossing sign
selftests/bpf: Test cross-sign 64bits range refinement
selftests/bpf: Update reg_bound range refinement logic
bpf: Improve bounds when s64 crosses sign boundary
bpf: Simplify bounds refinement from s32
selftests/bpf: Enable private stack tests for arm64
bpf, arm64: JIT support for private stack
bpf: Move bpf_jit_get_prog_name() to core.c
bpf, arm64: Fix fp initialization for exception boundary
umd: Remove usermode driver framework
bpf/preload: Don't select USERMODE_DRIVER
selftests/bpf: Fix test dynptr/test_dynptr_memset_xdp_chunks failure
selftests/bpf: Fix test dynptr/test_dynptr_copy_xdp failure
selftests/bpf: Increase xdp data size for arm64 64K page size
...
Pull networking updates from Jakub Kicinski:
"Core & protocols:
- Wrap datapath globals into net_aligned_data, to avoid false sharing
- Preserve MSG_ZEROCOPY in forwarding (e.g. out of a container)
- Add SO_INQ and SCM_INQ support to AF_UNIX
- Add SIOCINQ support to AF_VSOCK
- Add TCP_MAXSEG sockopt to MPTCP
- Add IPv6 force_forwarding sysctl to enable forwarding per interface
- Make TCP validation of whether packet fully fits in the receive
window and the rcv_buf more strict. With increased use of HW
aggregation a single "packet" can be multiple 100s of kB
- Add MSG_MORE flag to optimize large TCP transmissions via sockmap,
improves latency up to 33% for sockmap users
- Convert TCP send queue handling from tasklet to BH workque
- Improve BPF iteration over TCP sockets to see each socket exactly
once
- Remove obsolete and unused TCP RFC3517/RFC6675 loss recovery code
- Support enabling kernel threads for NAPI processing on per-NAPI
instance basis rather than a whole device. Fully stop the kernel
NAPI thread when threaded NAPI gets disabled. Previously thread
would stick around until ifdown due to tricky synchronization
- Allow multicast routing to take effect on locally-generated packets
- Add output interface argument for End.X in segment routing
- MCTP: add support for gateway routing, improve bind() handling
- Don't require rtnl_lock when fetching an IPv6 neighbor over Netlink
- Add a new neighbor flag ("extern_valid"), which cedes refresh
responsibilities to userspace. This is needed for EVPN multi-homing
where a neighbor entry for a multi-homed host needs to be synced
across all the VTEPs among which the host is multi-homed
- Support NUD_PERMANENT for proxy neighbor entries
- Add a new queuing discipline for IETF RFC9332 DualQ Coupled AQM
- Add sequence numbers to netconsole messages. Unregister
netconsole's console when all net targets are removed. Code
refactoring. Add a number of selftests
- Align IPSec inbound SA lookup to RFC 4301. Only SPI and protocol
should be used for an inbound SA lookup
- Support inspecting ref_tracker state via DebugFS
- Don't force bonding advertisement frames tx to ~333 ms boundaries.
Add broadcast_neighbor option to send ARP/ND on all bonded links
- Allow providing upcall pid for the 'execute' command in openvswitch
- Remove DCCP support from Netfilter's conntrack
- Disallow multiple packet duplications in the queuing layer
- Prevent use of deprecated iptables code on PREEMPT_RT
Driver API:
- Support RSS and hashing configuration over ethtool Netlink
- Add dedicated ethtool callbacks for getting and setting hashing
fields
- Add support for power budget evaluation strategy in PSE /
Power-over-Ethernet. Generate Netlink events for overcurrent etc
- Support DPLL phase offset monitoring across all device inputs.
Support providing clock reference and SYNC over separate DPLL
inputs
- Support traffic classes in devlink rate API for bandwidth
management
- Remove rtnl_lock dependency from UDP tunnel port configuration
Device drivers:
- Add a new Broadcom driver for 800G Ethernet (bnge)
- Add a standalone driver for Microchip ZL3073x DPLL
- Remove IBM's NETIUCV device driver
- Ethernet high-speed NICs:
- Broadcom (bnxt):
- support zero-copy Tx of DMABUF memory
- take page size into account for page pool recycling rings
- Intel (100G, ice, idpf):
- idpf: XDP and AF_XDP support preparations
- idpf: add flow steering
- add link_down_events statistic
- clean up the TSPLL code
- preparations for live VM migration
- nVidia/Mellanox:
- support zero-copy Rx/Tx interfaces (DMABUF and io_uring)
- optimize context memory usage for matchers
- expose serial numbers in devlink info
- support PCIe congestion metrics
- Meta (fbnic):
- add 25G, 50G, and 100G link modes to phylink
- support dumping FW logs
- Marvell/Cavium:
- support for CN20K generation of the Octeon chips
- Amazon:
- add HW clock (without timestamping, just hypervisor time access)
- Ethernet virtual:
- VirtIO net:
- support segmentation of UDP-tunnel-encapsulated packets
- Google (gve):
- support packet timestamping and clock synchronization
- Microsoft vNIC:
- add handler for device-originated servicing events
- allow dynamic MSI-X vector allocation
- support Tx bandwidth clamping
- Ethernet NICs consumer, and embedded:
- AMD:
- amd-xgbe: hardware timestamping and PTP clock support
- Broadcom integrated MACs (bcmgenet, bcmasp):
- use napi_complete_done() return value to support NAPI polling
- add support for re-starting auto-negotiation
- Broadcom switches (b53):
- support BCM5325 switches
- add bcm63xx EPHY power control
- Synopsys (stmmac):
- lots of code refactoring and cleanups
- TI:
- icssg-prueth: read firmware-names from device tree
- icssg: PRP offload support
- Microchip:
- lan78xx: convert to PHYLINK for improved PHY and MAC management
- ksz: add KSZ8463 switch support
- Intel:
- support similar queue priority scheme in multi-queue and
time-sensitive networking (taprio)
- support packet pre-emption in both
- RealTek (r8169):
- enable EEE at 5Gbps on RTL8126
- Airoha:
- add PPPoE offload support
- MDIO bus controller for Airoha AN7583
- Ethernet PHYs:
- support for the IPQ5018 internal GE PHY
- micrel KSZ9477 switch-integrated PHYs:
- add MDI/MDI-X control support
- add RX error counters
- add cable test support
- add Signal Quality Indicator (SQI) reporting
- dp83tg720: improve reset handling and reduce link recovery time
- support bcm54811 (and its MII-Lite interface type)
- air_en8811h: support resume/suspend
- support PHY counters for QCA807x and QCA808x
- support WoL for QCA807x
- CAN drivers:
- rcar_canfd: support for Transceiver Delay Compensation
- kvaser: report FW versions via devlink dev info
- WiFi:
- extended regulatory info support (6 GHz)
- add statistics and beacon monitor for Multi-Link Operation (MLO)
- support S1G aggregation, improve S1G support
- add Radio Measurement action fields
- support per-radio RTS threshold
- some work around how FIPS affects wifi, which was wrong (RC4 is
used by TKIP, not only WEP)
- improvements for unsolicited probe response handling
- WiFi drivers:
- RealTek (rtw88):
- IBSS mode for SDIO devices
- RealTek (rtw89):
- BT coexistence for MLO/WiFi7
- concurrent station + P2P support
- support for USB devices RTL8851BU/RTL8852BU
- Intel (iwlwifi):
- use embedded PNVM in (to be released) FW images to fix
compatibility issues
- many cleanups (unused FW APIs, PCIe code, WoWLAN)
- some FIPS interoperability
- MediaTek (mt76):
- firmware recovery improvements
- more MLO work
- Qualcomm/Atheros (ath12k):
- fix scan on multi-radio devices
- more EHT/Wi-Fi 7 features
- encapsulation/decapsulation offload
- Broadcom (brcm80211):
- support SDIO 43751 device
- Bluetooth:
- hci_event: add support for handling LE BIG Sync Lost event
- ISO: add socket option to report packet seqnum via CMSG
- ISO: support SCM_TIMESTAMPING for ISO TS
- Bluetooth drivers:
- intel_pcie: support Function Level Reset
- nxpuart: add support for 4M baudrate
- nxpuart: implement powerup sequence, reset, FW dump, and FW loading"
* tag 'net-next-6.17' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (1742 commits)
dpll: zl3073x: Fix build failure
selftests: bpf: fix legacy netfilter options
ipv6: annotate data-races around rt->fib6_nsiblings
ipv6: fix possible infinite loop in fib6_info_uses_dev()
ipv6: prevent infinite loop in rt6_nlmsg_size()
ipv6: add a retry logic in net6_rt_notify()
vrf: Drop existing dst reference in vrf_ip6_input_dst
net/sched: taprio: align entry index attr validation with mqprio
net: fsl_pq_mdio: use dev_err_probe
selftests: rtnetlink.sh: remove esp4_offload after test
vsock: remove unnecessary null check in vsock_getname()
igb: xsk: solve negative overflow of nb_pkts in zerocopy mode
stmmac: xsk: fix negative overflow of budget in zerocopy mode
dt-bindings: ieee802154: Convert at86rf230.txt yaml format
net: dsa: microchip: Disable PTP function of KSZ8463
net: dsa: microchip: Setup fiber ports for KSZ8463
net: dsa: microchip: Write switch MAC address differently for KSZ8463
net: dsa: microchip: Use different registers for KSZ8463
net: dsa: microchip: Add KSZ8463 switch support to KSZ DSA driver
dt-bindings: net: dsa: microchip: Add KSZ8463 switch support
...
Pull pidfs updates from Christian Brauner:
- persistent info
Persist exit and coredump information independent of whether anyone
currently holds a pidfd for the struct pid.
The current scheme allocated pidfs dentries on-demand repeatedly.
This scheme is reaching it's limits as it makes it impossible to pin
information that needs to be available after the task has exited or
coredumped and that should not be lost simply because the pidfd got
closed temporarily. The next opener should still see the stashed
information.
This is also a prerequisite for supporting extended attributes on
pidfds to allow attaching meta information to them.
If someone opens a pidfd for a struct pid a pidfs dentry is allocated
and stashed in pid->stashed. Once the last pidfd for the struct pid
is closed the pidfs dentry is released and removed from pid->stashed.
So if 10 callers create a pidfs dentry for the same struct pid
sequentially, i.e., each closing the pidfd before the other creates a
new one then a new pidfs dentry is allocated every time.
Because multiple tasks acquiring and releasing a pidfd for the same
struct pid can race with each another a task may still find a valid
pidfs entry from the previous task in pid->stashed and reuse it. Or
it might find a dead dentry in there and fail to reuse it and so
stashes a new pidfs dentry. Multiple tasks may race to stash a new
pidfs dentry but only one will succeed, the other ones will put their
dentry.
The current scheme aims to ensure that a pidfs dentry for a struct
pid can only be created if the task is still alive or if a pidfs
dentry already existed before the task was reaped and so exit
information has been was stashed in the pidfs inode.
That's great except that it's buggy. If a pidfs dentry is stashed in
pid->stashed after pidfs_exit() but before __unhash_process() is
called we will return a pidfd for a reaped task without exit
information being available.
The pidfds_pid_valid() check does not guard against this race as it
doens't sync at all with pidfs_exit(). The pid_has_task() check might
be successful simply because we're before __unhash_process() but
after pidfs_exit().
Introduce a new scheme where the lifetime of information associated
with a pidfs entry (coredump and exit information) isn't bound to the
lifetime of the pidfs inode but the struct pid itself.
The first time a pidfs dentry is allocated for a struct pid a struct
pidfs_attr will be allocated which will be used to store exit and
coredump information.
If all pidfs for the pidfs dentry are closed the dentry and inode can
be cleaned up but the struct pidfs_attr will stick until the struct
pid itself is freed. This will ensure minimal memory usage while
persisting relevant information.
The new scheme has various advantages. First, it allows to close the
race where we end up handing out a pidfd for a reaped task for which
no exit information is available. Second, it minimizes memory usage.
Third, it allows to remove complex lifetime tracking via dentries
when registering a struct pid with pidfs. There's no need to get or
put a reference. Instead, the lifetime of exit and coredump
information associated with a struct pid is bound to the lifetime of
struct pid itself.
- extended attributes
Now that we have a way to persist information for pidfs dentries we
can start supporting extended attributes on pidfds. This will allow
userspace to attach meta information to tasks.
One natural extension would be to introduce a custom pidfs.* extended
attribute space and allow for the inheritance of extended attributes
across fork() and exec().
The first simple scheme will allow privileged userspace to set
trusted extended attributes on pidfs inodes.
- Allow autonomous pidfs file handles
Various filesystems such as pidfs and drm support opening file
handles without having to require a file descriptor to identify the
filesystem. The filesystem are global single instances and can be
trivially identified solely on the information encoded in the file
handle.
This makes it possible to not have to keep or acquire a sentinal file
descriptor just to pass it to open_by_handle_at() to identify the
filesystem. That's especially useful when such sentinel file
descriptor cannot or should not be acquired.
For pidfs this means a file handle can function as full replacement
for storing a pid in a file. Instead a file handle can be stored and
reopened purely based on the file handle.
Such autonomous file handles can be opened with or without specifying
a a file descriptor. If no proper file descriptor is used the
FD_PIDFS_ROOT sentinel must be passed. This allows us to define
further special negative fd sentinels in the future.
Userspace can trivially test for support by trying to open the file
handle with an invalid file descriptor.
- Allow pidfds for reaped tasks with SCM_PIDFD messages
This is a logical continuation of the earlier work to create pidfds
for reaped tasks through the SO_PEERPIDFD socket option merged in
923ea4d448 ("Merge patch series "net, pidfs: enable handing out
pidfds for reaped sk->sk_peer_pid"").
- Two minor fixes:
* Fold fs_struct->{lock,seq} into a seqlock
* Don't bother with path_{get,put}() in unix_open_file()
* tag 'vfs-6.17-rc1.pidfs' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (37 commits)
don't bother with path_get()/path_put() in unix_open_file()
fold fs_struct->{lock,seq} into a seqlock
selftests: net: extend SCM_PIDFD test to cover stale pidfds
af_unix: enable handing out pidfds for reaped tasks in SCM_PIDFD
af_unix: stash pidfs dentry when needed
af_unix/scm: fix whitespace errors
af_unix: introduce and use scm_replace_pid() helper
af_unix: introduce unix_skb_to_scm helper
af_unix: rework unix_maybe_add_creds() to allow sleep
selftests/pidfd: decode pidfd file handles withou having to specify an fd
fhandle, pidfs: support open_by_handle_at() purely based on file handle
uapi/fcntl: add FD_PIDFS_ROOT
uapi/fcntl: add FD_INVALID
fcntl/pidfd: redefine PIDFD_SELF_THREAD_GROUP
uapi/fcntl: mark range as reserved
fhandle: reflow get_path_anchor()
pidfs: add pidfs_root_path() helper
fhandle: rename to get_path_anchor()
fhandle: hoist copy_from_user() above get_path_from_fd()
fhandle: raise FILEID_IS_DIR in handle_type
...
Pull namespace updates from Christian Brauner:
"This contains namespace updates. This time specifically for nsfs:
- Userspace heavily relies on the root inode numbers for namespaces
to identify the initial namespaces. That's already a hard
dependency. So we cannot change that anymore. Move the initial
inode numbers to a public header and align the only two namespaces
that currently don't do that with all the other namespaces.
- The root inode of /proc having a fixed inode number has been part
of the core kernel ABI since its inception, and recently some
userspace programs (mainly container runtimes) have started to
explicitly depend on this behaviour.
The main reason this is useful to userspace is that by checking
that a suspect /proc handle has fstype PROC_SUPER_MAGIC and is
PROCFS_ROOT_INO, they can then use openat2() together with
RESOLVE_{NO_{XDEV,MAGICLINK},BENEATH} to ensure that there isn't a
bind-mount that replaces some procfs file with a different one.
This kind of attack has lead to security issues in container
runtimes in the past (such as CVE-2019-19921) and libraries like
libpathrs[1] use this feature of procfs to provide safe procfs
handling functions"
* tag 'vfs-6.17-rc1.nsfs' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
uapi: export PROCFS_ROOT_INO
mntns: use stable inode number for initial mount ns
netns: use stable inode number for initial mount ns
nsfs: move root inode number to uapi
Merge in late fixes to prepare for the 6.17 net-next PR.
Conflicts:
net/core/neighbour.c
1bbb76a899 ("neighbour: Fix null-ptr-deref in neigh_flush_dev().")
13a936bb99 ("neighbour: Protect tbl->phash_buckets[] with a dedicated mutex.")
03dc03fa04 ("neighbor: Add NTF_EXT_VALIDATED flag for externally validated entries")
Adjacent changes:
drivers/net/usb/usbnet.c
0d9cfc9b8c ("net: usbnet: Avoid potential RCU stall on LINK_CHANGE event")
2c04d279e8 ("net: usb: Convert tasklet API to new bottom half workqueue mechanism")
net/ipv6/route.c
31d7d67ba1 ("ipv6: annotate data-races around rt->fib6_nsiblings")
1caf272972 ("ipv6: adopt dst_dev() helper")
3b3ccf9ed0 ("net: Remove unnecessary NULL check for lwtunnel_fill_encap()")
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
