Commit Graph

17461 Commits

Author SHA1 Message Date
Jakub Kicinski
9f06f87fef net: skbuff: generalize the skb->decrypted bit
The ->decrypted bit can be reused for other crypto protocols.
Remove the direct dependency on TLS, add helpers to clean up
the ifdefs leaking out everywhere.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2024-04-06 17:34:31 +01:00
Jakub Kicinski
cf1ca1f66d Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
Cross-merge networking fixes after downstream PR.

Conflicts:

net/ipv4/ip_gre.c
  17af420545 ("erspan: make sure erspan_base_hdr is present in skb->head")
  5832c4a77d ("ip_tunnel: convert __be16 tunnel flags to bitmaps")
https://lore.kernel.org/all/20240402103253.3b54a1cf@canb.auug.org.au/

Adjacent changes:

net/ipv6/ip6_fib.c
  d21d40605b ("ipv6: Fix infinite recursion in fib6_dump_done().")
  5fc68320c1 ("ipv6: remove RTNL protection from inet6_dump_fib()")

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2024-04-04 18:01:07 -07:00
Jakub Kicinski
8c73e8b595 Merge tag 'wireless-next-2024-04-03' of git://git.kernel.org/pub/scm/linux/kernel/git/wireless/wireless-next
Kalle Valo says:

====================
wireless-next patches for v6.10

The first "new features" pull request for v6.10 with changes both in
stack and in drivers. The big thing in this pull request is that
wireless subsystem is now almost free of sparse warnings. There's only
one warning left in ath11k which was introduced in v6.9-rc1 and will
be fixed via the wireless tree.

Realtek drivers continue to improve, now we have support for RTL8922AE
and RTL8723CS devices. ath11k also has long waited support for P2P.

This time we have a small conflict in iwlwifi, Stephen has an example
merge resolution which should help with fixing the conflict:

https://lore.kernel.org/all/20240326100945.765b8caf@canb.auug.org.au/

Major changes:

rtw89
 * RTL8922AE Wi-Fi 7 PCI device support

rtw88
 * RTL8723CS SDIO device support

iwlwifi
 * don't support puncturing in 5 GHz
 * support monitor mode on passive channels
 * BZ-W device support
 * P2P with HE/EHT support

ath11k
 * P2P support for QCA6390, WCN6855 and QCA2066

* tag 'wireless-next-2024-04-03' of git://git.kernel.org/pub/scm/linux/kernel/git/wireless/wireless-next: (122 commits)
  wifi: mt76: mt7915: workaround dubious x | !y warning
  wifi: mwl8k: Avoid -Wflex-array-member-not-at-end warnings
  wifi: ti: Avoid a hundred -Wflex-array-member-not-at-end warnings
  wifi: iwlwifi: mvm: fix check in iwl_mvm_sta_fw_id_mask
  net: rfkill: gpio: Convert to platform remove callback returning void
  wifi: mac80211: use kvcalloc() for codel vars
  wifi: iwlwifi: reconfigure TLC during HW restart
  wifi: iwlwifi: mvm: don't change BA sessions during restart
  wifi: iwlwifi: mvm: select STA mask only for active links
  wifi: iwlwifi: mvm: set wider BW OFDMA ignore correctly
  wifi: iwlwifi: Add support for LARI_CONFIG_CHANGE_CMD cmd v9
  wifi: iwlwifi: mvm: Declare HE/EHT capabilities support for P2P interfaces
  wifi: iwlwifi: mvm: Remove outdated comment
  wifi: iwlwifi: add support for BZ_W
  wifi: iwlwifi: Print a specific device name.
  wifi: iwlwifi: remove wrong CRF_IDs
  wifi: iwlwifi: remove devices that never came out
  wifi: iwlwifi: mvm: mark EMLSR disabled in cleanup iterator
  wifi: iwlwifi: mvm: fix active link counting during recovery
  wifi: iwlwifi: mvm: assign link STA ID lookups during restart
  ...
====================

Link: https://lore.kernel.org/r/20240403093625.CF515C433C7@smtp.kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2024-04-03 19:36:57 -07:00
Haiyang Zhang
c0de6ab920 net: mana: Fix Rx DMA datasize and skb_over_panic
mana_get_rxbuf_cfg() aligns the RX buffer's DMA datasize to be
multiple of 64. So a packet slightly bigger than mtu+14, say 1536,
can be received and cause skb_over_panic.

Sample dmesg:
[ 5325.237162] skbuff: skb_over_panic: text:ffffffffc043277a len:1536 put:1536 head:ff1100018b517000 data:ff1100018b517100 tail:0x700 end:0x6ea dev:<NULL>
[ 5325.243689] ------------[ cut here ]------------
[ 5325.245748] kernel BUG at net/core/skbuff.c:192!
[ 5325.247838] invalid opcode: 0000 [#1] PREEMPT SMP NOPTI
[ 5325.258374] RIP: 0010:skb_panic+0x4f/0x60
[ 5325.302941] Call Trace:
[ 5325.304389]  <IRQ>
[ 5325.315794]  ? skb_panic+0x4f/0x60
[ 5325.317457]  ? asm_exc_invalid_op+0x1f/0x30
[ 5325.319490]  ? skb_panic+0x4f/0x60
[ 5325.321161]  skb_put+0x4e/0x50
[ 5325.322670]  mana_poll+0x6fa/0xb50 [mana]
[ 5325.324578]  __napi_poll+0x33/0x1e0
[ 5325.326328]  net_rx_action+0x12e/0x280

As discussed internally, this alignment is not necessary. To fix
this bug, remove it from the code. So oversized packets will be
marked as CQE_RX_TRUNCATED by NIC, and dropped.

Cc: stable@vger.kernel.org
Fixes: 2fbbd712ba ("net: mana: Enable RX path to handle various MTU sizes")
Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
Reviewed-by: Dexuan Cui <decui@microsoft.com>
Link: https://lore.kernel.org/r/1712087316-20886-1-git-send-email-haiyangz@microsoft.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2024-04-03 19:32:03 -07:00
Kuniyuki Iwashima
118f457da9 af_unix: Remove lock dance in unix_peek_fds().
In the previous GC implementation, the shape of the inflight socket
graph was not expected to change while GC was in progress.

MSG_PEEK was tricky because it could install inflight fd silently
and transform the graph.

Let's say we peeked a fd, which was a listening socket, and accept()ed
some embryo sockets from it.  The garbage collection algorithm would
have been confused because the set of sockets visited in scan_inflight()
would change within the same GC invocation.

That's why we placed spin_lock(&unix_gc_lock) and spin_unlock() in
unix_peek_fds() with a fat comment.

In the new GC implementation, we no longer garbage-collect the socket
if it exists in another queue, that is, if it has a bridge to another
SCC.  Also, accept() will require the lock if it has edges.

Thus, we need not do the complicated lock dance.

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://lore.kernel.org/r/20240401173125.92184-3-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2024-04-03 19:27:13 -07:00
Jason Xing
9a79c65f00 tcp/dccp: complete lockless accesses to sk->sk_max_ack_backlog
Since commit 099ecf59f0 ("net: annotate lockless accesses to
sk->sk_max_ack_backlog") decided to handle the sk_max_ack_backlog
locklessly, there is one more function mostly called in TCP/DCCP
cases. So this patch completes it:)

Signed-off-by: Jason Xing <kernelxing@tencent.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20240331090521.71965-1-kerneljasonxing@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2024-04-02 18:21:13 -07:00
Jakub Kicinski
cd7209628c genetlink: remove linux/genetlink.h
genetlink.h is a shell of what used to be a combined uAPI
and kernel header over a decade ago. It has fewer than
10 lines of code. Merge it into net/genetlink.h.
In some ways it'd be better to keep the combined header
under linux/ but it would make looking through git history
harder.

Acked-by: Sven Eckelmann <sven@narfation.org>
Link: https://lore.kernel.org/r/20240329175710.291749-4-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2024-04-01 21:44:34 -07:00
Eric Dumazet
1eeb504357 tcp/dccp: do not care about families in inet_twsk_purge()
We lost ability to unload ipv6 module a long time ago.

Instead of calling expensive inet_twsk_purge() twice,
we can handle all families in one round.

Also remove an extra line added in my prior patch,
per Kuniyuki Iwashima feedback.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/netdev/20240327192934.6843-1-kuniyu@amazon.com/
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://lore.kernel.org/r/20240329153203.345203-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2024-04-01 21:27:58 -07:00
Eric Dumazet
58169ec9c4 inet: preserve const qualifier in inet_csk()
We can change inet_csk() to propagate its argument const qualifier,
thanks to container_of_const().

We have to fix few places that had mistakes, like tcp_bound_rto().

Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20240329144931.295800-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2024-04-01 21:27:08 -07:00
Eric Dumazet
c62fdf5b11 net: rps: add rps_input_queue_head_add() helper
process_backlog() can batch increments of sd->input_queue_head,
saving some memory bandwidth.

Also add READ_ONCE()/WRITE_ONCE() annotations around
sd->input_queue_head accesses.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2024-04-01 11:28:32 +01:00
Eric Dumazet
36b83ffcf2 net: rps: change input_queue_tail_incr_save()
input_queue_tail_incr_save() is incrementing the sd queue_tail
and save it in the flow last_qtail.

Two issues here :

- no lock protects the write on last_qtail, we should use appropriate
  annotations.

- We can perform this write after releasing the per-cpu backlog lock,
  to decrease this lock hold duration (move away the cache line miss)

Also move input_queue_head_incr() and rps helpers to include/net/rps.h,
while adding rps_ prefix to better reflect their role.

v2: Fixed a build issue (Jakub and kernel build bots)

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2024-04-01 11:28:32 +01:00
Michal Swiatkowski
6dd514f481 pfcp: always set pfcp metadata
In PFCP receive path set metadata needed by flower code to do correct
classification based on this metadata.

Signed-off-by: Michal Swiatkowski <michal.swiatkowski@linux.intel.com>
Signed-off-by: Marcin Szycik <marcin.szycik@linux.intel.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: Alexander Lobakin <aleksander.lobakin@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2024-04-01 10:49:28 +01:00
Wojciech Drewek
76c8764ef3 pfcp: add PFCP module
Packet Forwarding Control Protocol (PFCP) is a 3GPP Protocol
used between the control plane and the user plane function.
It is specified in TS 29.244[1].

Note that this module is not designed to support this Protocol
in the kernel space. There is no support for parsing any PFCP messages.
There is no API that could be used by any userspace daemon.
Basically it does not support PFCP. This protocol is sophisticated
and there is no need for implementing it in the kernel. The purpose
of this module is to allow users to setup software and hardware offload
of PFCP packets using tc tool.

When user requests to create a PFCP device, a new socket is created.
The socket is set up with port number 8805 which is specific for
PFCP [29.244 4.2.2]. This allow to receive PFCP request messages,
response messages use other ports.

Note that only one PFCP netdev can be created.

Only IPv4 is supported at this time.

[1] https://portal.3gpp.org/desktopmodules/Specifications/SpecificationDetails.aspx?specificationId=3111

Signed-off-by: Wojciech Drewek <wojciech.drewek@intel.com>
Signed-off-by: Marcin Szycik <marcin.szycik@linux.intel.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: Alexander Lobakin <aleksander.lobakin@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2024-04-01 10:49:28 +01:00
Alexander Lobakin
5832c4a77d ip_tunnel: convert __be16 tunnel flags to bitmaps
Historically, tunnel flags like TUNNEL_CSUM or TUNNEL_ERSPAN_OPT
have been defined as __be16. Now all of those 16 bits are occupied
and there's no more free space for new flags.
It can't be simply switched to a bigger container with no
adjustments to the values, since it's an explicit Endian storage,
and on LE systems (__be16)0x0001 equals to
(__be64)0x0001000000000000.
We could probably define new 64-bit flags depending on the
Endianness, i.e. (__be64)0x0001 on BE and (__be64)0x00010000... on
LE, but that would introduce an Endianness dependency and spawn a
ton of Sparse warnings. To mitigate them, all of those places which
were adjusted with this change would be touched anyway, so why not
define stuff properly if there's no choice.

Define IP_TUNNEL_*_BIT counterparts as a bit number instead of the
value already coded and a fistful of <16 <-> bitmap> converters and
helpers. The two flags which have a different bit position are
SIT_ISATAP_BIT and VTI_ISVTI_BIT, as they were defined not as
__cpu_to_be16(), but as (__force __be16), i.e. had different
positions on LE and BE. Now they both have strongly defined places.
Change all __be16 fields which were used to store those flags, to
IP_TUNNEL_DECLARE_FLAGS() -> DECLARE_BITMAP(__IP_TUNNEL_FLAG_NUM) ->
unsigned long[1] for now, and replace all TUNNEL_* occurrences to
their bitmap counterparts. Use the converters in the places which talk
to the userspace, hardware (NFP) or other hosts (GRE header). The rest
must explicitly use the new flags only. This must be done at once,
otherwise there will be too many conversions throughout the code in
the intermediate commits.
Finally, disable the old __be16 flags for use in the kernel code
(except for the two 'irregular' flags mentioned above), to prevent
any accidental (mis)use of them. For the userspace, nothing is
changed, only additions were made.

Most noticeable bloat-o-meter difference (.text):

vmlinux:	307/-1 (306)
gre.ko:		62/0 (62)
ip_gre.ko:	941/-217 (724)	[*]
ip_tunnel.ko:	390/-900 (-510)	[**]
ip_vti.ko:	138/0 (138)
ip6_gre.ko:	534/-18 (516)	[*]
ip6_tunnel.ko:	118/-10 (108)

[*] gre_flags_to_tnl_flags() grew, but still is inlined
[**] ip_tunnel_find() got uninlined, hence such decrease

The average code size increase in non-extreme case is 100-200 bytes
per module, mostly due to sizeof(long) > sizeof(__be16), as
%__IP_TUNNEL_FLAG_NUM is less than %BITS_PER_LONG and the compilers
are able to expand the majority of bitmap_*() calls here into direct
operations on scalars.

Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: Alexander Lobakin <aleksander.lobakin@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2024-04-01 10:49:28 +01:00
Alexander Lobakin
117aef12a7 ip_tunnel: use a separate struct to store tunnel params in the kernel
Unlike IPv6 tunnels which use purely-kernel __ip6_tnl_parm structure
to store params inside the kernel, IPv4 tunnel code uses the same
ip_tunnel_parm which is being used to talk with the userspace.
This makes it difficult to alter or add any fields or use a
different format for whatever data.
Define struct ip_tunnel_parm_kern, a 1:1 copy of ip_tunnel_parm for
now, and use it throughout the code. Define the pieces, where the copy
user <-> kernel happens, as standalone functions, and copy the data
there field-by-field, so that the kernel-side structure could be easily
modified later on and the users wouldn't have to care about this.

Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: Alexander Lobakin <aleksander.lobakin@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2024-04-01 10:49:28 +01:00
Johannes Berg
e8058a49e6 netlink: introduce type-checking attribute iteration
There are, especially with multi-attr arrays, many cases
of needing to iterate all attributes of a specific type
in a netlink message or a nested attribute. Add specific
macros to support that case.

Also convert many instances using this spatch:

    @@
    iterator nla_for_each_attr;
    iterator name nla_for_each_attr_type;
    identifier nla;
    expression head, len, rem;
    expression ATTR;
    type T;
    identifier x;
    @@
    -nla_for_each_attr(nla, head, len, rem)
    +nla_for_each_attr_type(nla, ATTR, head, len, rem)
     {
    <... T x; ...>
    -if (nla_type(nla) == ATTR) {
     ...
    -}
     }

    @@
    identifier nla;
    iterator nla_for_each_nested;
    iterator name nla_for_each_nested_type;
    expression attr, rem;
    expression ATTR;
    type T;
    identifier x;
    @@
    -nla_for_each_nested(nla, attr, rem)
    +nla_for_each_nested_type(nla, ATTR, attr, rem)
     {
    <... T x; ...>
    -if (nla_type(nla) == ATTR) {
     ...
    -}
     }

    @@
    iterator nla_for_each_attr;
    iterator name nla_for_each_attr_type;
    identifier nla;
    expression head, len, rem;
    expression ATTR;
    type T;
    identifier x;
    @@
    -nla_for_each_attr(nla, head, len, rem)
    +nla_for_each_attr_type(nla, ATTR, head, len, rem)
     {
    <... T x; ...>
    -if (nla_type(nla) != ATTR) continue;
     ...
     }

    @@
    identifier nla;
    iterator nla_for_each_nested;
    iterator name nla_for_each_nested_type;
    expression attr, rem;
    expression ATTR;
    type T;
    identifier x;
    @@
    -nla_for_each_nested(nla, attr, rem)
    +nla_for_each_nested_type(nla, ATTR, attr, rem)
     {
    <... T x; ...>
    -if (nla_type(nla) != ATTR) continue;
     ...
     }

Although I had to undo one bad change this made, and
I also adjusted some other code for whitespace and to
use direct variable initialization now.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Link: https://lore.kernel.org/r/20240328203144.b5a6c895fb80.I1869b44767379f204998ff44dd239803f39c23e0@changeid
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2024-03-29 15:06:02 -07:00
Eric Dumazet
1abe267f17 net: add sk_wake_async_rcu() helper
While looking at UDP receive performance, I saw sk_wake_async()
was no longer inlined.

This matters at least on AMD Zen1-4 platforms (see SRSO)

This might be because rcu_read_lock() and rcu_read_unlock()
are no longer nops in recent kernels ?

Add sk_wake_async_rcu() variant, which must be called from
contexts already holding rcu lock.

As SOCK_FASYNC is deprecated in modern days, use unlikely()
to give a hint to the compiler.

sk_wake_async_rcu() is properly inlined from
__udp_enqueue_schedule_skb() and sock_def_readable().

Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20240328144032.1864988-5-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2024-03-29 15:03:11 -07:00
Kuniyuki Iwashima
4090fa373f af_unix: Replace garbage collection algorithm.
If we find a dead SCC during iteration, we call unix_collect_skb()
to splice all skb in the SCC to the global sk_buff_head, hitlist.

After iterating all SCC, we unlock unix_gc_lock and purge the queue.

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Acked-by: Paolo Abeni <pabeni@redhat.com>
Link: https://lore.kernel.org/r/20240325202425.60930-15-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2024-03-29 08:28:42 -07:00
Kuniyuki Iwashima
bfdb01283e af_unix: Assign a unique index to SCC.
The definition of the lowlink in Tarjan's algorithm is the
smallest index of a vertex that is reachable with at most one
back-edge in SCC.  This is not useful for a cross-edge.

If we start traversing from A in the following graph, the final
lowlink of D is 3.  The cross-edge here is one between D and C.

  A -> B -> D   D = (4, 3)  (index, lowlink)
  ^    |    |   C = (3, 1)
  |    V    |   B = (2, 1)
  `--- C <--'   A = (1, 1)

This is because the lowlink of D is updated with the index of C.

In the following patch, we detect a dead SCC by checking two
conditions for each vertex.

  1) vertex has no edge directed to another SCC (no bridge)
  2) vertex's out_degree is the same as the refcount of its file

If 1) is false, there is a receiver of all fds of the SCC and
its ancestor SCC.

To evaluate 1), we need to assign a unique index to each SCC and
assign it to all vertices in the SCC.

This patch changes the lowlink update logic for cross-edge so
that in the example above, the lowlink of D is updated with the
lowlink of C.

  A -> B -> D   D = (4, 1)  (index, lowlink)
  ^    |    |   C = (3, 1)
  |    V    |   B = (2, 1)
  `--- C <--'   A = (1, 1)

Then, all vertices in the same SCC have the same lowlink, and we
can quickly find the bridge connecting to different SCC if exists.

However, it is no longer called lowlink, so we rename it to
scc_index.  (It's sometimes called lowpoint.)

Also, we add a global variable to hold the last index used in DFS
so that we do not reset the initial index in each DFS.

This patch can be squashed to the SCC detection patch but is
split deliberately for anyone wondering why lowlink is not used
as used in the original Tarjan's algorithm and many reference
implementations.

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Acked-by: Paolo Abeni <pabeni@redhat.com>
Link: https://lore.kernel.org/r/20240325202425.60930-13-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2024-03-29 08:28:33 -07:00
Kuniyuki Iwashima
ba31b4a4e1 af_unix: Save O(n) setup of Tarjan's algo.
Before starting Tarjan's algorithm, we need to mark all vertices
as unvisited.  We can save this O(n) setup by reserving two special
indices (0, 1) and using two variables.

The first time we link a vertex to unix_unvisited_vertices, we set
unix_vertex_unvisited_index to index.

During DFS, we can see that the index of unvisited vertices is the
same as unix_vertex_unvisited_index.

When we finalise SCC later, we set unix_vertex_grouped_index to each
vertex's index.

Then, we can know (i) that the vertex is on the stack if the index
of a visited vertex is >= 2 and (ii) that it is not on the stack and
belongs to a different SCC if the index is unix_vertex_grouped_index.

After the whole algorithm, all indices of vertices are set as
unix_vertex_grouped_index.

Next time we start DFS, we know that all unvisited vertices have
unix_vertex_grouped_index, and we can use unix_vertex_unvisited_index
as the not-on-stack marker.

To use the same variable in __unix_walk_scc(), we can swap
unix_vertex_(grouped|unvisited)_index at the end of Tarjan's
algorithm.

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Acked-by: Paolo Abeni <pabeni@redhat.com>
Link: https://lore.kernel.org/r/20240325202425.60930-10-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2024-03-29 08:28:20 -07:00
Kuniyuki Iwashima
dcf70df204 af_unix: Fix up unix_edge.successor for embryo socket.
To garbage collect inflight AF_UNIX sockets, we must define the
cyclic reference appropriately.  This is a bit tricky if the loop
consists of embryo sockets.

Suppose that the fd of AF_UNIX socket A is passed to D and the fd B
to C and that C and D are embryo sockets of A and B, respectively.
It may appear that there are two separate graphs, A (-> D) and
B (-> C), but this is not correct.

     A --. .-- B
          X
     C <-' `-> D

Now, D holds A's refcount, and C has B's refcount, so unix_release()
will never be called for A and B when we close() them.  However, no
one can call close() for D and C to free skbs holding refcounts of A
and B because C/D is in A/B's receive queue, which should have been
purged by unix_release() for A and B.

So, here's another type of cyclic reference.  When a fd of an AF_UNIX
socket is passed to an embryo socket, the reference is indirectly held
by its parent listening socket.

  .-> A                            .-> B
  |   `- sk_receive_queue          |   `- sk_receive_queue
  |      `- skb                    |      `- skb
  |         `- sk == C             |         `- sk == D
  |            `- sk_receive_queue |           `- sk_receive_queue
  |               `- skb +---------'               `- skb +-.
  |                                                         |
  `---------------------------------------------------------'

Technically, the graph must be denoted as A <-> B instead of A (-> D)
and B (-> C) to find such a cyclic reference without touching each
socket's receive queue.

  .-> A --. .-- B <-.
  |        X        |  ==  A <-> B
  `-- C <-' `-> D --'

We apply this fixup during GC by fetching the real successor by
unix_edge_successor().

When we call accept(), we clear unix_sock.listener under unix_gc_lock
not to confuse GC.

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Acked-by: Paolo Abeni <pabeni@redhat.com>
Link: https://lore.kernel.org/r/20240325202425.60930-9-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2024-03-29 08:28:14 -07:00
Kuniyuki Iwashima
aed6ecef55 af_unix: Save listener for embryo socket.
This is a prep patch for the following change, where we need to
fetch the listening socket from the successor embryo socket
during GC.

We add a new field to struct unix_sock to save a pointer to a
listening socket.

We set it when connect() creates a new socket, and clear it when
accept() is called.

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Acked-by: Paolo Abeni <pabeni@redhat.com>
Link: https://lore.kernel.org/r/20240325202425.60930-8-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2024-03-29 08:28:10 -07:00
Kuniyuki Iwashima
3484f06317 af_unix: Detect Strongly Connected Components.
In the new GC, we use a simple graph algorithm, Tarjan's Strongly
Connected Components (SCC) algorithm, to find cyclic references.

The algorithm visits every vertex exactly once using depth-first
search (DFS).

DFS starts by pushing an input vertex to a stack and assigning it
a unique number.  Two fields, index and lowlink, are initialised
with the number, but lowlink could be updated later during DFS.

If a vertex has an edge to an unvisited inflight vertex, we visit
it and do the same processing.  So, we will have vertices in the
stack in the order they appear and number them consecutively in
the same order.

If a vertex has a back-edge to a visited vertex in the stack,
we update the predecessor's lowlink with the successor's index.

After iterating edges from the vertex, we check if its index
equals its lowlink.

If the lowlink is different from the index, it shows there was a
back-edge.  Then, we go backtracking and propagate the lowlink to
its predecessor and resume the previous edge iteration from the
next edge.

If the lowlink is the same as the index, we pop vertices before
and including the vertex from the stack.  Then, the set of vertices
is SCC, possibly forming a cycle.  At the same time, we move the
vertices to unix_visited_vertices.

When we finish the algorithm, all vertices in each SCC will be
linked via unix_vertex.scc_entry.

Let's take an example.  We have a graph including five inflight
vertices (F is not inflight):

  A -> B -> C -> D -> E (-> F)
       ^         |
       `---------'

Suppose that we start DFS from C.  We will visit C, D, and B first
and initialise their index and lowlink.  Then, the stack looks like
this:

  > B = (3, 3)  (index, lowlink)
    D = (2, 2)
    C = (1, 1)

When checking B's edge to C, we update B's lowlink with C's index
and propagate it to D.

    B = (3, 1)  (index, lowlink)
  > D = (2, 1)
    C = (1, 1)

Next, we visit E, which has no edge to an inflight vertex.

  > E = (4, 4)  (index, lowlink)
    B = (3, 1)
    D = (2, 1)
    C = (1, 1)

When we leave from E, its index and lowlink are the same, so we
pop E from the stack as single-vertex SCC.  Next, we leave from
B and D but do nothing because their lowlink are different from
their index.

    B = (3, 1)  (index, lowlink)
    D = (2, 1)
  > C = (1, 1)

Then, we leave from C, whose index and lowlink are the same, so
we pop B, D and C as SCC.

Last, we do DFS for the rest of vertices, A, which is also a
single-vertex SCC.

Finally, each unix_vertex.scc_entry is linked as follows:

  A -.  B -> C -> D  E -.
  ^  |  ^         |  ^  |
  `--'  `---------'  `--'

We use SCC later to decide whether we can garbage-collect the
sockets.

Note that we still cannot detect SCC properly if an edge points
to an embryo socket.  The following two patches will sort it out.

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Acked-by: Paolo Abeni <pabeni@redhat.com>
Link: https://lore.kernel.org/r/20240325202425.60930-7-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2024-03-29 08:28:04 -07:00
Kuniyuki Iwashima
6ba76fd284 af_unix: Iterate all vertices by DFS.
The new GC will use a depth first search graph algorithm to find
cyclic references.  The algorithm visits every vertex exactly once.

Here, we implement the DFS part without recursion so that no one
can abuse it.

unix_walk_scc() marks every vertex unvisited by initialising index
as UNIX_VERTEX_INDEX_UNVISITED and iterates inflight vertices in
unix_unvisited_vertices and call __unix_walk_scc() to start DFS from
an arbitrary vertex.

__unix_walk_scc() iterates all edges starting from the vertex and
explores the neighbour vertices with DFS using edge_stack.

After visiting all neighbours, __unix_walk_scc() moves the visited
vertex to unix_visited_vertices so that unix_walk_scc() will not
restart DFS from the visited vertex.

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Acked-by: Paolo Abeni <pabeni@redhat.com>
Link: https://lore.kernel.org/r/20240325202425.60930-6-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2024-03-29 08:27:59 -07:00
Kuniyuki Iwashima
42f298c06b af_unix: Link struct unix_edge when queuing skb.
Just before queuing skb with inflight fds, we call scm_stat_add(),
which is a good place to set up the preallocated struct unix_vertex
and struct unix_edge in UNIXCB(skb).fp.

Then, we call unix_add_edges() and construct the directed graph
as follows:

  1. Set the inflight socket's unix_sock to unix_edge.predecessor.
  2. Set the receiver's unix_sock to unix_edge.successor.
  3. Set the preallocated vertex to inflight socket's unix_sock.vertex.
  4. Link inflight socket's unix_vertex.entry to unix_unvisited_vertices.
  5. Link unix_edge.vertex_entry to the inflight socket's unix_vertex.edges.

Let's say we pass the fd of AF_UNIX socket A to B and the fd of B
to C.  The graph looks like this:

  +-------------------------+
  | unix_unvisited_vertices | <-------------------------.
  +-------------------------+                           |
  +                                                     |
  |     +--------------+             +--------------+   |         +--------------+
  |     |  unix_sock A | <---. .---> |  unix_sock B | <-|-. .---> |  unix_sock C |
  |     +--------------+     | |     +--------------+   | | |     +--------------+
  | .-+ |    vertex    |     | | .-+ |    vertex    |   | | |     |    vertex    |
  | |   +--------------+     | | |   +--------------+   | | |     +--------------+
  | |                        | | |                      | | |
  | |   +--------------+     | | |   +--------------+   | | |
  | '-> |  unix_vertex |     | | '-> |  unix_vertex |   | | |
  |     +--------------+     | |     +--------------+   | | |
  `---> |    entry     | +---------> |    entry     | +-' | |
        |--------------|     | |     |--------------|     | |
        |    edges     | <-. | |     |    edges     | <-. | |
        +--------------+   | | |     +--------------+   | | |
                           | | |                        | | |
    .----------------------' | | .----------------------' | |
    |                        | | |                        | |
    |   +--------------+     | | |   +--------------+     | |
    |   |   unix_edge  |     | | |   |   unix_edge  |     | |
    |   +--------------+     | | |   +--------------+     | |
    `-> | vertex_entry |     | | `-> | vertex_entry |     | |
        |--------------|     | |     |--------------|     | |
        |  predecessor | +---' |     |  predecessor | +---' |
        |--------------|       |     |--------------|       |
        |   successor  | +-----'     |   successor  | +-----'
        +--------------+             +--------------+

Henceforth, we denote such a graph as A -> B (-> C).

Now, we can express all inflight fd graphs that do not contain
embryo sockets.  We will support the particular case later.

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Acked-by: Paolo Abeni <pabeni@redhat.com>
Link: https://lore.kernel.org/r/20240325202425.60930-4-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2024-03-29 08:27:50 -07:00