linux.git/net/l2tp, branch v6.16

net: move misc netdev_lock flavors to a separate header

2025-03-08T17:06:50+00:00

Move the more esoteric helpers for netdev instance lock to
a dedicated header. This avoids growing netdevice.h to infinity
and makes rebuilding the kernel much faster (after touching
the header with the helpers).

The main netdev_lock() / netdev_unlock() functions are used
in static inlines in netdevice.h and will probably be used
most commonly, so keep them in netdevice.h.

Acked-by: Stanislav Fomichev 
Link: https://patch.msgid.link/20250307183006.2312761-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski

ppp: use IFF_NO_QUEUE in virtual interfaces

2025-03-05T01:11:17+00:00

For PPPoE, PPTP, and PPPoL2TP, the start_xmit() function directly
forwards packets to the underlying network stack and never returns
anything other than 1. So these interfaces do not require a qdisc,
and the IFF_NO_QUEUE flag should be set.

Introduces a direct_xmit flag in struct ppp_channel to indicate when
IFF_NO_QUEUE should be applied. The flag is set in ppp_connect_channel()
for relevant protocols.

While at it, remove the usused latency member from struct ppp_channel.

Signed-off-by: Qingfang Deng 
Reviewed-by: Toke Høiland-Jørgensen 
Link: https://patch.msgid.link/20250301135517.695809-1-dqfext@gmail.com
Signed-off-by: Jakub Kicinski

ipv6: replace ipcm6_init calls with ipcm6_init_sk

2025-02-19T02:27:20+00:00

This initializes tclass and dontfrag before cmsg parsing, removing the
need for explicit checks against -1 in each caller.

Leave hlimit set to -1, because its full initialization
(in ip6_sk_dst_hoplimit) requires more state (dst, flowi6, ..).

This also prepares for calling sockcm_init in a follow-on patch.

Signed-off-by: Willem de Bruijn 
Reviewed-by: David Ahern 
Link: https://patch.msgid.link/20250214222720.3205500-7-willemdebruijn.kernel@gmail.com
Signed-off-by: Jakub Kicinski

l2tp: Use inet_sk_init_flowi4() in l2tp_ip_sendmsg().

2024-12-20T21:50:09+00:00

Use inet_sk_init_flowi4() to automatically initialise the flowi4
structure in l2tp_ip_sendmsg() instead of passing parameters manually
to ip_route_output_ports().

Override ->daddr with the value passed in the msghdr structure if
provided.

Signed-off-by: Guillaume Nault 
Reviewed-by: James Chapman 
Link: https://patch.msgid.link/2ff22a3560c5050228928456662b80b9c84a8fe4.1734357769.git.gnault@redhat.com
Signed-off-by: Jakub Kicinski

l2tp: Handle eth stats using NETDEV_PCPU_STAT_DSTATS.

2024-12-11T13:57:26+00:00

l2tp_eth uses the TSTATS infrastructure (dev_sw_netstats_*()) for RX
and TX packet counters and DEV_STATS_INC for dropped counters.

Consolidate that using the DSTATS infrastructure, which can
handle both packet counters and packet drops. Statistics that don't
fit DSTATS are still updated atomically with DEV_STATS_INC().

This change is inspired by the introduction of DSTATS helpers and
their use in other udp tunnel drivers:
Link: https://lore.kernel.org/all/cover.1733313925.git.gnault@redhat.com/

Signed-off-by: James Chapman 
Reviewed-by: Guillaume Nault 
Signed-off-by: David S. Miller

net/l2tp: fix warning in l2tp_exit_net found by syzbot

2024-11-26T08:27:07+00:00

In l2tp's net exit handler, we check that an IDR is empty before
destroying it:

	WARN_ON_ONCE(!idr_is_empty(&pn->l2tp_tunnel_idr));
	idr_destroy(&pn->l2tp_tunnel_idr);

By forcing memory allocation failures in idr_alloc_32, syzbot is able
to provoke a condition where idr_is_empty returns false despite there
being no items in the IDR. This turns out to be because the radix tree
of the IDR contains only internal radix-tree nodes and it is this that
causes idr_is_empty to return false. The internal nodes are cleaned by
idr_destroy.

Use idr_for_each to check that the IDR is empty instead of
idr_is_empty to avoid the problem.

Reported-by: syzbot+332fe1e67018625f63c9@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=332fe1e67018625f63c9
Fixes: 73d33bd063c4 ("l2tp: avoid using drain_workqueue in l2tp_pre_exit_net")
Signed-off-by: James Chapman 
Link: https://patch.msgid.link/20241118140411.1582555-1-jchapman@katalix.com
Signed-off-by: Paolo Abeni

genetlink: hold RCU in genlmsg_mcast()

2024-10-16T00:52:58+00:00

While running net selftests with CONFIG_PROVE_RCU_LIST=y I saw
one lockdep splat [1].

genlmsg_mcast() uses for_each_net_rcu(), and must therefore hold RCU.

Instead of letting all callers guard genlmsg_multicast_allns()
with a rcu_read_lock()/rcu_read_unlock() pair, do it in genlmsg_mcast().

This also means the @flags parameter is useless, we need to always use
GFP_ATOMIC.

[1]
[10882.424136] =============================
[10882.424166] WARNING: suspicious RCU usage
[10882.424309] 6.12.0-rc2-virtme #1156 Not tainted
[10882.424400] -----------------------------
[10882.424423] net/netlink/genetlink.c:1940 RCU-list traversed in non-reader section!!
[10882.424469]
other info that might help us debug this:

[10882.424500]
rcu_scheduler_active = 2, debug_locks = 1
[10882.424744] 2 locks held by ip/15677:
[10882.424791] #0: ffffffffb6b491b0 (cb_lock){++++}-{3:3}, at: genl_rcv (net/netlink/genetlink.c:1219)
[10882.426334] #1: ffffffffb6b49248 (genl_mutex){+.+.}-{3:3}, at: genl_rcv_msg (net/netlink/genetlink.c:61 net/netlink/genetlink.c:57 net/netlink/genetlink.c:1209)
[10882.426465]
stack backtrace:
[10882.426805] CPU: 14 UID: 0 PID: 15677 Comm: ip Not tainted 6.12.0-rc2-virtme #1156
[10882.426919] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
[10882.427046] Call Trace:
[10882.427131]  
[10882.427244] dump_stack_lvl (lib/dump_stack.c:123)
[10882.427335] lockdep_rcu_suspicious (kernel/locking/lockdep.c:6822)
[10882.427387] genlmsg_multicast_allns (net/netlink/genetlink.c:1940 (discriminator 7) net/netlink/genetlink.c:1977 (discriminator 7))
[10882.427436] l2tp_tunnel_notify.constprop.0 (net/l2tp/l2tp_netlink.c:119) l2tp_netlink
[10882.427683] l2tp_nl_cmd_tunnel_create (net/l2tp/l2tp_netlink.c:253) l2tp_netlink
[10882.427748] genl_family_rcv_msg_doit (net/netlink/genetlink.c:1115)
[10882.427834] genl_rcv_msg (net/netlink/genetlink.c:1195 net/netlink/genetlink.c:1210)
[10882.427877] ? __pfx_l2tp_nl_cmd_tunnel_create (net/l2tp/l2tp_netlink.c:186) l2tp_netlink
[10882.427927] ? __pfx_genl_rcv_msg (net/netlink/genetlink.c:1201)
[10882.427959] netlink_rcv_skb (net/netlink/af_netlink.c:2551)
[10882.428069] genl_rcv (net/netlink/genetlink.c:1220)
[10882.428095] netlink_unicast (net/netlink/af_netlink.c:1332 net/netlink/af_netlink.c:1357)
[10882.428140] netlink_sendmsg (net/netlink/af_netlink.c:1901)
[10882.428210] ____sys_sendmsg (net/socket.c:729 (discriminator 1) net/socket.c:744 (discriminator 1) net/socket.c:2607 (discriminator 1))

Fixes: 33f72e6f0c67 ("l2tp : multicast notification to the registered listeners")
Signed-off-by: Eric Dumazet 
Cc: James Chapman 
Cc: Tom Parkin 
Cc: Johannes Berg 
Link: https://patch.msgid.link/20241011171217.3166614-1-edumazet@google.com
Signed-off-by: Jakub Kicinski

l2tp: remove unneeded null check in l2tp_v2_session_get_next

2024-09-04T23:39:32+00:00

Commit aa92c1cec92b ("l2tp: add tunnel/session get_next helpers") uses
idr_get_next APIs to iterate over l2tp session IDR lists.  Sessions in
l2tp_v2_session_idr always have a non-null session->tunnel pointer
since l2tp_session_register sets it before inserting the session into
the IDR. Therefore the null check on session->tunnel in
l2tp_v2_session_get_next is redundant and can be removed. Removing the
check avoids a warning from lkp.

Reported-by: kernel test robot 
Closes: https://lore.kernel.org/r/202408111407.HtON8jqa-lkp@intel.com/
CC: Dan Carpenter 
Signed-off-by: James Chapman 
Acked-by: Tom Parkin 
Reviewed-by: Simon Horman 
Link: https://patch.msgid.link/20240903113547.1261048-1-jchapman@katalix.com
Signed-off-by: Jakub Kicinski

netdev_features: convert NETIF_F_LLTX to dev->lltx

2024-09-03T09:36:43+00:00

NETIF_F_LLTX can't be changed via Ethtool and is not a feature,
rather an attribute, very similar to IFF_NO_QUEUE (and hot).
Free one netdev_features_t bit and make it a "hot" private flag.

Signed-off-by: Alexander Lobakin 
Signed-off-by: Paolo Abeni

l2tp: avoid using drain_workqueue in l2tp_pre_exit_net

2024-08-27T20:37:22+00:00

Recent commit fc7ec7f554d7 ("l2tp: delete sessions using work queue")
incorrectly uses drain_workqueue. The use of drain_workqueue in
l2tp_pre_exit_net is flawed because the workqueue is shared by all
nets and it is therefore possible for new work items to be queued
for other nets while drain_workqueue runs.

Instead of using drain_workqueue, use __flush_workqueue twice. The
first one will run all tunnel delete work items and any work already
queued. When tunnel delete work items are run, they may queue
new session delete work items, which the second __flush_workqueue will
run.

In l2tp_exit_net, warn if any of the net's idr lists are not empty.

Fixes: fc7ec7f554d7 ("l2tp: delete sessions using work queue")
Signed-off-by: James Chapman 
Link: https://patch.msgid.link/20240823142257.692667-1-jchapman@katalix.com
Signed-off-by: Jakub Kicinski