Before the cited commit, the kernel unconditionally embedded SCM
credentials to skb for embryo sockets even when both the sender
and listener disabled SO_PASSCRED and SO_PASSPIDFD.
Now, the credentials are added to skb only when configured by the
sender or the listener.
However, as reported in the link below, it caused a regression for
some programs that assume credentials are included in every skb,
but sometimes not now.
The only problematic scenario would be that a socket starts listening
before setting the option. Then, there will be 2 types of non-small
race window, where a client can send skb without credentials, which
the peer receives as an "invalid" message (and aborts the connection
it seems ?):
Client Server
------ ------
s1.listen() <-- No SO_PASS{CRED,PIDFD}
s2.connect()
s2.send() <-- w/o cred
s1.setsockopt(SO_PASS{CRED,PIDFD})
s2.send() <-- w/ cred
or
Client Server
------ ------
s1.listen() <-- No SO_PASS{CRED,PIDFD}
s2.connect()
s2.send() <-- w/o cred
s3, _ = s1.accept() <-- Inherit cred options
s2.send() <-- w/o cred but not set yet
s3.setsockopt(SO_PASS{CRED,PIDFD})
s2.send() <-- w/ cred
It's unfortunate that buggy programs depend on the behaviour,
but let's restore the previous behaviour.
Fixes: 3f84d577b7 ("af_unix: Inherit sk_flags at connect().")
Reported-by: Jacek Łuczak <difrost.kernel@gmail.com>
Closes: https://lore.kernel.org/all/68d38b0b-1666-4974-85d4-15575789c8d4@gmail.com/
Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
Tested-by: Christian Heusel <christian@heusel.eu>
Tested-by: André Almeida <andrealmeid@igalia.com>
Tested-by: Jacek Łuczak <difrost.kernel@gmail.com>
Link: https://patch.msgid.link/20250611202758.3075858-1-kuni1840@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Core
----
- Implement the Device Memory TCP transmit path, allowing zero-copy
data transmission on top of TCP from e.g. GPU memory to the wire.
- Move all the IPv6 routing tables management outside the RTNL scope,
under its own lock and RCU. The route control path is now 3x times
faster.
- Convert queue related netlink ops to instance lock, reducing
again the scope of the RTNL lock. This improves the control plane
scalability.
- Refactor the software crc32c implementation, removing unneeded
abstraction layers and improving significantly the related
micro-benchmarks.
- Optimize the GRO engine for UDP-tunneled traffic, for a 10%
performance improvement in related stream tests.
- Cover more per-CPU storage with local nested BH locking; this is a
prep work to remove the current per-CPU lock in local_bh_disable()
on PREMPT_RT.
- Introduce and use nlmsg_payload helper, combining buffer bounds
verification with accessing payload carried by netlink messages.
Netfilter
---------
- Rewrite the procfs conntrack table implementation, improving
considerably the dump performance. A lot of user-space tools
still use this interface.
- Implement support for wildcard netdevice in netdev basechain
and flowtables.
- Integrate conntrack information into nft trace infrastructure.
- Export set count and backend name to userspace, for better
introspection.
BPF
---
- BPF qdisc support: BPF-qdisc can be implemented with BPF struct_ops
programs and can be controlled in similar way to traditional qdiscs
using the "tc qdisc" command.
- Refactor the UDP socket iterator, addressing long standing issues
WRT duplicate hits or missed sockets.
Protocols
---------
- Improve TCP receive buffer auto-tuning and increase the default
upper bound for the receive buffer; overall this improves the single
flow maximum thoughput on 200Gbs link by over 60%.
- Add AFS GSSAPI security class to AF_RXRPC; it provides transport
security for connections to the AFS fileserver and VL server.
- Improve TCP multipath routing, so that the sources address always
matches the nexthop device.
- Introduce SO_PASSRIGHTS for AF_UNIX, to allow disabling SCM_RIGHTS,
and thus preventing DoS caused by passing around problematic FDs.
- Retire DCCP socket. DCCP only receives updates for bugs, and major
distros disable it by default. Its removal allows for better
organisation of TCP fields to reduce the number of cache lines hit
in the fast path.
- Extend TCP drop-reason support to cover PAWS checks.
Driver API
----------
- Reorganize PTP ioctl flag support to require an explicit opt-in for
the drivers, avoiding the problem of drivers not rejecting new
unsupported flags.
- Converted several device drivers to timestamping APIs.
- Introduce per-PHY ethtool dump helpers, improving the support for
dump operations targeting PHYs.
Tests and tooling
-----------------
- Add support for classic netlink in user space C codegen, so that
ynl-c can now read, create and modify links, routes addresses and
qdisc layer configuration.
- Add ynl sub-types for binary attributes, allowing ynl-c to output
known struct instead of raw binary data, clarifying the classic
netlink output.
- Extend MPTCP selftests to improve the code-coverage.
- Add tests for XDP tail adjustment in AF_XDP.
New hardware / drivers
----------------------
- OpenVPN virtual driver: offload OpenVPN data channels processing
to the kernel-space, increasing the data transfer throughput WRT
the user-space implementation.
- Renesas glue driver for the gigabit ethernet RZ/V2H(P) SoC.
- Broadcom asp-v3.0 ethernet driver.
- AMD Renoir ethernet device.
- ReakTek MT9888 2.5G ethernet PHY driver.
- Aeonsemi 10G C45 PHYs driver.
Drivers
-------
- Ethernet high-speed NICs:
- nVidia/Mellanox (mlx5):
- refactor the stearing table handling to reduce significantly
the amount of memory used
- add support for complex matches in H/W flow steering
- improve flow streeing error handling
- convert to netdev instance locking
- Intel (100G, ice, igb, ixgbe, idpf):
- ice: add switchdev support for LLDP traffic over VF
- ixgbe: add firmware manipulation and regions devlink support
- igb: introduce support for frame transmission premption
- igb: adds persistent NAPI configuration
- idpf: introduce RDMA support
- idpf: add initial PTP support
- Meta (fbnic):
- extend hardware stats coverage
- add devlink dev flash support
- Broadcom (bnxt):
- add support for RX-side device memory TCP
- Wangxun (txgbe):
- implement support for udp tunnel offload
- complete PTP and SRIOV support for AML 25G/10G devices
- Ethernet NICs embedded and virtual:
- Google (gve):
- add device memory TCP TX support
- Amazon (ena):
- support persistent per-NAPI config
- Airoha:
- add H/W support for L2 traffic offload
- add per flow stats for flow offloading
- RealTek (rtl8211): add support for WoL magic packet
- Synopsys (stmmac):
- dwmac-socfpga 1000BaseX support
- add Loongson-2K3000 support
- introduce support for hardware-accelerated VLAN stripping
- Broadcom (bcmgenet):
- expose more H/W stats
- Freescale (enetc, dpaa2-eth):
- enetc: add MAC filter, VLAN filter RSS and loopback support
- dpaa2-eth: convert to H/W timestamping APIs
- vxlan: convert FDB table to rhashtable, for better scalabilty
- veth: apply qdisc backpressure on full ring to reduce TX drops
- Ethernet switches:
- Microchip (kzZ88x3): add ETS scheduler support
- Ethernet PHYs:
- RealTek (rtl8211):
- add support for WoL magic packet
- add support for PHY LEDs
- CAN:
- Adds RZ/G3E CANFD support to the rcar_canfd driver.
- Preparatory work for CAN-XL support.
- Add self-tests framework with support for CAN physical interfaces.
- WiFi:
- mac80211:
- scan improvements with multi-link operation (MLO)
- Qualcomm (ath12k):
- enable AHB support for IPQ5332
- add monitor interface support to QCN9274
- add multi-link operation support to WCN7850
- add 802.11d scan offload support to WCN7850
- monitor mode for WCN7850, better 6 GHz regulatory
- Qualcomm (ath11k):
- restore hibernation support
- MediaTek (mt76):
- WiFi-7 improvements
- implement support for mt7990
- Intel (iwlwifi):
- enhanced multi-link single-radio (EMLSR) support on 5 GHz links
- rework device configuration
- RealTek (rtw88):
- improve throughput for RTL8814AU
- RealTek (rtw89):
- add multi-link operation support
- STA/P2P concurrency improvements
- support different SAR configs by antenna
- Bluetooth:
- introduce HCI Driver protocol
- btintel_pcie: do not generate coredump for diagnostic events
- btusb: add HCI Drv commands for configuring altsetting
- btusb: add RTL8851BE device 0x0bda:0xb850
- btusb: add new VID/PID 13d3/3584 for MT7922
- btusb: add new VID/PID 13d3/3630 and 13d3/3613 for MT7925
- btnxpuart: implement host-wakeup feature
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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Merge tag 'net-next-6.16' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next
Pull networking updates from Paolo Abeni:
"Core:
- Implement the Device Memory TCP transmit path, allowing zero-copy
data transmission on top of TCP from e.g. GPU memory to the wire.
- Move all the IPv6 routing tables management outside the RTNL scope,
under its own lock and RCU. The route control path is now 3x times
faster.
- Convert queue related netlink ops to instance lock, reducing again
the scope of the RTNL lock. This improves the control plane
scalability.
- Refactor the software crc32c implementation, removing unneeded
abstraction layers and improving significantly the related
micro-benchmarks.
- Optimize the GRO engine for UDP-tunneled traffic, for a 10%
performance improvement in related stream tests.
- Cover more per-CPU storage with local nested BH locking; this is a
prep work to remove the current per-CPU lock in local_bh_disable()
on PREMPT_RT.
- Introduce and use nlmsg_payload helper, combining buffer bounds
verification with accessing payload carried by netlink messages.
Netfilter:
- Rewrite the procfs conntrack table implementation, improving
considerably the dump performance. A lot of user-space tools still
use this interface.
- Implement support for wildcard netdevice in netdev basechain and
flowtables.
- Integrate conntrack information into nft trace infrastructure.
- Export set count and backend name to userspace, for better
introspection.
BPF:
- BPF qdisc support: BPF-qdisc can be implemented with BPF struct_ops
programs and can be controlled in similar way to traditional qdiscs
using the "tc qdisc" command.
- Refactor the UDP socket iterator, addressing long standing issues
WRT duplicate hits or missed sockets.
Protocols:
- Improve TCP receive buffer auto-tuning and increase the default
upper bound for the receive buffer; overall this improves the
single flow maximum thoughput on 200Gbs link by over 60%.
- Add AFS GSSAPI security class to AF_RXRPC; it provides transport
security for connections to the AFS fileserver and VL server.
- Improve TCP multipath routing, so that the sources address always
matches the nexthop device.
- Introduce SO_PASSRIGHTS for AF_UNIX, to allow disabling SCM_RIGHTS,
and thus preventing DoS caused by passing around problematic FDs.
- Retire DCCP socket. DCCP only receives updates for bugs, and major
distros disable it by default. Its removal allows for better
organisation of TCP fields to reduce the number of cache lines hit
in the fast path.
- Extend TCP drop-reason support to cover PAWS checks.
Driver API:
- Reorganize PTP ioctl flag support to require an explicit opt-in for
the drivers, avoiding the problem of drivers not rejecting new
unsupported flags.
- Converted several device drivers to timestamping APIs.
- Introduce per-PHY ethtool dump helpers, improving the support for
dump operations targeting PHYs.
Tests and tooling:
- Add support for classic netlink in user space C codegen, so that
ynl-c can now read, create and modify links, routes addresses and
qdisc layer configuration.
- Add ynl sub-types for binary attributes, allowing ynl-c to output
known struct instead of raw binary data, clarifying the classic
netlink output.
- Extend MPTCP selftests to improve the code-coverage.
- Add tests for XDP tail adjustment in AF_XDP.
New hardware / drivers:
- OpenVPN virtual driver: offload OpenVPN data channels processing to
the kernel-space, increasing the data transfer throughput WRT the
user-space implementation.
- Renesas glue driver for the gigabit ethernet RZ/V2H(P) SoC.
- Broadcom asp-v3.0 ethernet driver.
- AMD Renoir ethernet device.
- ReakTek MT9888 2.5G ethernet PHY driver.
- Aeonsemi 10G C45 PHYs driver.
Drivers:
- Ethernet high-speed NICs:
- nVidia/Mellanox (mlx5):
- refactor the steering table handling to significantly
reduce the amount of memory used
- add support for complex matches in H/W flow steering
- improve flow streeing error handling
- convert to netdev instance locking
- Intel (100G, ice, igb, ixgbe, idpf):
- ice: add switchdev support for LLDP traffic over VF
- ixgbe: add firmware manipulation and regions devlink support
- igb: introduce support for frame transmission premption
- igb: adds persistent NAPI configuration
- idpf: introduce RDMA support
- idpf: add initial PTP support
- Meta (fbnic):
- extend hardware stats coverage
- add devlink dev flash support
- Broadcom (bnxt):
- add support for RX-side device memory TCP
- Wangxun (txgbe):
- implement support for udp tunnel offload
- complete PTP and SRIOV support for AML 25G/10G devices
- Ethernet NICs embedded and virtual:
- Google (gve):
- add device memory TCP TX support
- Amazon (ena):
- support persistent per-NAPI config
- Airoha:
- add H/W support for L2 traffic offload
- add per flow stats for flow offloading
- RealTek (rtl8211): add support for WoL magic packet
- Synopsys (stmmac):
- dwmac-socfpga 1000BaseX support
- add Loongson-2K3000 support
- introduce support for hardware-accelerated VLAN stripping
- Broadcom (bcmgenet):
- expose more H/W stats
- Freescale (enetc, dpaa2-eth):
- enetc: add MAC filter, VLAN filter RSS and loopback support
- dpaa2-eth: convert to H/W timestamping APIs
- vxlan: convert FDB table to rhashtable, for better scalabilty
- veth: apply qdisc backpressure on full ring to reduce TX drops
- Ethernet switches:
- Microchip (kzZ88x3): add ETS scheduler support
- Ethernet PHYs:
- RealTek (rtl8211):
- add support for WoL magic packet
- add support for PHY LEDs
- CAN:
- Adds RZ/G3E CANFD support to the rcar_canfd driver.
- Preparatory work for CAN-XL support.
- Add self-tests framework with support for CAN physical interfaces.
- WiFi:
- mac80211:
- scan improvements with multi-link operation (MLO)
- Qualcomm (ath12k):
- enable AHB support for IPQ5332
- add monitor interface support to QCN9274
- add multi-link operation support to WCN7850
- add 802.11d scan offload support to WCN7850
- monitor mode for WCN7850, better 6 GHz regulatory
- Qualcomm (ath11k):
- restore hibernation support
- MediaTek (mt76):
- WiFi-7 improvements
- implement support for mt7990
- Intel (iwlwifi):
- enhanced multi-link single-radio (EMLSR) support on 5 GHz links
- rework device configuration
- RealTek (rtw88):
- improve throughput for RTL8814AU
- RealTek (rtw89):
- add multi-link operation support
- STA/P2P concurrency improvements
- support different SAR configs by antenna
- Bluetooth:
- introduce HCI Driver protocol
- btintel_pcie: do not generate coredump for diagnostic events
- btusb: add HCI Drv commands for configuring altsetting
- btusb: add RTL8851BE device 0x0bda:0xb850
- btusb: add new VID/PID 13d3/3584 for MT7922
- btusb: add new VID/PID 13d3/3630 and 13d3/3613 for MT7925
- btnxpuart: implement host-wakeup feature"
* tag 'net-next-6.16' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (1611 commits)
selftests/bpf: Fix bpf selftest build warning
selftests: netfilter: Fix skip of wildcard interface test
net: phy: mscc: Stop clearing the the UDPv4 checksum for L2 frames
net: openvswitch: Fix the dead loop of MPLS parse
calipso: Don't call calipso functions for AF_INET sk.
selftests/tc-testing: Add a test for HFSC eltree double add with reentrant enqueue behaviour on netem
net_sched: hfsc: Address reentrant enqueue adding class to eltree twice
octeontx2-pf: QOS: Refactor TC_HTB_LEAF_DEL_LAST callback
octeontx2-pf: QOS: Perform cache sync on send queue teardown
net: mana: Add support for Multi Vports on Bare metal
net: devmem: ncdevmem: remove unused variable
net: devmem: ksft: upgrade rx test to send 1K data
net: devmem: ksft: add 5 tuple FS support
net: devmem: ksft: add exit_wait to make rx test pass
net: devmem: ksft: add ipv4 support
net: devmem: preserve sockc_err
page_pool: fix ugly page_pool formatting
net: devmem: move list_add to net_devmem_bind_dmabuf.
selftests: netfilter: nft_queue.sh: include file transfer duration in log message
net: phy: mscc: Fix memory leak when using one step timestamping
...
As long as recvmsg() or recvmmsg() is used with cmsg, it is not
possible to avoid receiving file descriptors via SCM_RIGHTS.
This behaviour has occasionally been flagged as problematic, as
it can be (ab)used to trigger DoS during close(), for example, by
passing a FUSE-controlled fd or a hung NFS fd.
For instance, as noted on the uAPI Group page [0], an untrusted peer
could send a file descriptor pointing to a hung NFS mount and then
close it. Once the receiver calls recvmsg() with msg_control, the
descriptor is automatically installed, and then the responsibility
for the final close() now falls on the receiver, which may result
in blocking the process for a long time.
Regarding this, systemd calls cmsg_close_all() [1] after each
recvmsg() to close() unwanted file descriptors sent via SCM_RIGHTS.
However, this cannot work around the issue at all, because the final
fput() may still occur on the receiver's side once sendmsg() with
SCM_RIGHTS succeeds. Also, even filtering by LSM at recvmsg() does
not work for the same reason.
Thus, we need a better way to refuse SCM_RIGHTS at sendmsg().
Let's introduce SO_PASSRIGHTS to disable SCM_RIGHTS.
Note that this option is enabled by default for backward
compatibility.
Link: https://uapi-group.org/kernel-features/#disabling-reception-of-scm_rights-for-af_unix-sockets #[0]
Link: https://github.com/systemd/systemd/blob/v257.5/src/basic/fd-util.c#L612-L628 #[1]
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
For SOCK_STREAM embryo sockets, the SO_PASS{CRED,PIDFD,SEC} options
are inherited from the parent listen()ing socket.
Currently, this inheritance happens at accept(), because these
attributes were stored in sk->sk_socket->flags and the struct socket
is not allocated until accept().
This leads to unintentional behaviour.
When a peer sends data to an embryo socket in the accept() queue,
unix_maybe_add_creds() embeds credentials into the skb, even if
neither the peer nor the listener has enabled these options.
If the option is enabled, the embryo socket receives the ancillary
data after accept(). If not, the data is silently discarded.
This conservative approach works for SO_PASS{CRED,PIDFD,SEC}, but
would not for SO_PASSRIGHTS; once an SCM_RIGHTS with a hung file
descriptor was sent, it'd be game over.
To avoid this, we will need to preserve SOCK_PASSRIGHTS even on embryo
sockets.
Commit aed6ecef55 ("af_unix: Save listener for embryo socket.")
made it possible to access the parent's flags in sendmsg() via
unix_sk(other)->listener->sk->sk_socket->flags, but this introduces
an unnecessary condition that is irrelevant for most sockets,
accept()ed sockets and clients.
Therefore, we moved SOCK_PASSXXX into struct sock.
Let’s inherit sk->sk_scm_recv_flags at connect() to avoid receiving
SCM_RIGHTS on embryo sockets created from a parent with SO_PASSRIGHTS=0.
Note that the parent socket is locked in connect() so we don't need
READ_ONCE() for sk_scm_recv_flags.
Now, we can remove !other->sk_socket check in unix_maybe_add_creds()
to avoid slow SOCK_PASS{CRED,PIDFD} handling for embryo sockets
created from a parent with SO_PASS{CRED,PIDFD}=0.
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
As explained in the next patch, SO_PASSRIGHTS would have a problem
if we assigned a corresponding bit to socket->flags, so it must be
managed in struct sock.
Mixing socket->flags and sk->sk_flags for similar options will look
confusing, and sk->sk_flags does not have enough space on 32bit system.
Also, as mentioned in commit 16e5726269 ("af_unix: dont send
SCM_CREDENTIALS by default"), SOCK_PASSCRED and SOCK_PASSPID handling
is known to be slow, and managing the flags in struct socket cannot
avoid that for embryo sockets.
Let's move SOCK_PASS{CRED,PIDFD,SEC} to struct sock.
While at it, other SOCK_XXX flags in net.h are grouped as enum.
Note that assign_bit() was atomic, so the writer side is moved down
after lock_sock() in setsockopt(), but the bit is only read once
in sendmsg() and recvmsg(), so lock_sock() is not needed there.
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
We will move SOCK_PASS{CRED,PIDFD,SEC} from struct socket.flags
to struct sock for better handling with SOCK_PASSRIGHTS.
Then, we don't need to access struct socket in maybe_add_creds().
Let's pass struct sock to maybe_add_creds() and its caller
queue_oob().
While at it, we append the unix_ prefix and fix double spaces
around the pid assignment.
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Currently, the same checks for SOCK_PASSCRED and SOCK_PASSPIDFD
are scattered across many places.
Let's centralise the bit tests to make the following changes cleaner.
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Coredumping currently supports two modes:
(1) Dumping directly into a file somewhere on the filesystem.
(2) Dumping into a pipe connected to a usermode helper process
spawned as a child of the system_unbound_wq or kthreadd.
For simplicity I'm mostly ignoring (1). There's probably still some
users of (1) out there but processing coredumps in this way can be
considered adventurous especially in the face of set*id binaries.
The most common option should be (2) by now. It works by allowing
userspace to put a string into /proc/sys/kernel/core_pattern like:
|/usr/lib/systemd/systemd-coredump %P %u %g %s %t %c %h
The "|" at the beginning indicates to the kernel that a pipe must be
used. The path following the pipe indicator is a path to a binary that
will be spawned as a usermode helper process. Any additional parameters
pass information about the task that is generating the coredump to the
binary that processes the coredump.
In the example core_pattern shown above systemd-coredump is spawned as a
usermode helper. There's various conceptual consequences of this
(non-exhaustive list):
- systemd-coredump is spawned with file descriptor number 0 (stdin)
connected to the read-end of the pipe. All other file descriptors are
closed. That specifically includes 1 (stdout) and 2 (stderr). This has
already caused bugs because userspace assumed that this cannot happen
(Whether or not this is a sane assumption is irrelevant.).
- systemd-coredump will be spawned as a child of system_unbound_wq. So
it is not a child of any userspace process and specifically not a
child of PID 1. It cannot be waited upon and is in a weird hybrid
upcall which are difficult for userspace to control correctly.
- systemd-coredump is spawned with full kernel privileges. This
necessitates all kinds of weird privilege dropping excercises in
userspace to make this safe.
- A new usermode helper has to be spawned for each crashing process.
This series adds a new mode:
(3) Dumping into an AF_UNIX socket.
Userspace can set /proc/sys/kernel/core_pattern to:
@/path/to/coredump.socket
The "@" at the beginning indicates to the kernel that an AF_UNIX
coredump socket will be used to process coredumps.
The coredump socket must be located in the initial mount namespace.
When a task coredumps it opens a client socket in the initial network
namespace and connects to the coredump socket.
- The coredump server uses SO_PEERPIDFD to get a stable handle on the
connected crashing task. The retrieved pidfd will provide a stable
reference even if the crashing task gets SIGKILLed while generating
the coredump.
- By setting core_pipe_limit non-zero userspace can guarantee that the
crashing task cannot be reaped behind it's back and thus process all
necessary information in /proc/<pid>. The SO_PEERPIDFD can be used to
detect whether /proc/<pid> still refers to the same process.
The core_pipe_limit isn't used to rate-limit connections to the
socket. This can simply be done via AF_UNIX sockets directly.
- The pidfd for the crashing task will grow new information how the task
coredumps.
- The coredump server should mark itself as non-dumpable.
- A container coredump server in a separate network namespace can simply
bind to another well-know address and systemd-coredump fowards
coredumps to the container.
- Coredumps could in the future also be handled via per-user/session
coredump servers that run only with that users privileges.
The coredump server listens on the coredump socket and accepts a
new coredump connection. It then retrieves SO_PEERPIDFD for the
client, inspects uid/gid and hands the accepted client to the users
own coredump handler which runs with the users privileges only
(It must of coure pay close attention to not forward crashing suid
binaries.).
The new coredump socket will allow userspace to not have to rely on
usermode helpers for processing coredumps and provides a safer way to
handle them instead of relying on super privileged coredumping helpers
that have and continue to cause significant CVEs.
This will also be significantly more lightweight since no fork()+exec()
for the usermodehelper is required for each crashing process. The
coredump server in userspace can e.g., just keep a worker pool.
Link: https://lore.kernel.org/20250516-work-coredump-socket-v8-4-664f3caf2516@kernel.org
Acked-by: Luca Boccassi <luca.boccassi@gmail.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com>
Reviewed-by: Jann Horn <jannh@google.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
SO_PEERPIDFD currently doesn't support handing out pidfds if the
sk->sk_peer_pid thread-group leader has already been reaped. In this
case it currently returns EINVAL. Userspace still wants to get a pidfd
for a reaped process to have a stable handle it can pass on.
This is especially useful now that it is possible to retrieve exit
information through a pidfd via the PIDFD_GET_INFO ioctl()'s
PIDFD_INFO_EXIT flag.
Another summary has been provided by David in [1]:
> A pidfd can outlive the task it refers to, and thus user-space must
> already be prepared that the task underlying a pidfd is gone at the time
> they get their hands on the pidfd. For instance, resolving the pidfd to
> a PID via the fdinfo must be prepared to read `-1`.
>
> Despite user-space knowing that a pidfd might be stale, several kernel
> APIs currently add another layer that checks for this. In particular,
> SO_PEERPIDFD returns `EINVAL` if the peer-task was already reaped,
> but returns a stale pidfd if the task is reaped immediately after the
> respective alive-check.
>
> This has the unfortunate effect that user-space now has two ways to
> check for the exact same scenario: A syscall might return
> EINVAL/ESRCH/... *or* the pidfd might be stale, even though there is no
> particular reason to distinguish both cases. This also propagates
> through user-space APIs, which pass on pidfds. They must be prepared to
> pass on `-1` *or* the pidfd, because there is no guaranteed way to get a
> stale pidfd from the kernel.
> Userspace must already deal with a pidfd referring to a reaped task as
> the task may exit and get reaped at any time will there are still many
> pidfds referring to it.
In order to allow handing out reaped pidfd SO_PEERPIDFD needs to ensure
that PIDFD_INFO_EXIT information is available whenever a pidfd for a
reaped task is created by PIDFD_INFO_EXIT. The uapi promises that reaped
pidfds are only handed out if it is guaranteed that the caller sees the
exit information:
TEST_F(pidfd_info, success_reaped)
{
struct pidfd_info info = {
.mask = PIDFD_INFO_CGROUPID | PIDFD_INFO_EXIT,
};
/*
* Process has already been reaped and PIDFD_INFO_EXIT been set.
* Verify that we can retrieve the exit status of the process.
*/
ASSERT_EQ(ioctl(self->child_pidfd4, PIDFD_GET_INFO, &info), 0);
ASSERT_FALSE(!!(info.mask & PIDFD_INFO_CREDS));
ASSERT_TRUE(!!(info.mask & PIDFD_INFO_EXIT));
ASSERT_TRUE(WIFEXITED(info.exit_code));
ASSERT_EQ(WEXITSTATUS(info.exit_code), 0);
}
To hand out pidfds for reaped processes we thus allocate a pidfs entry
for the relevant sk->sk_peer_pid at the time the sk->sk_peer_pid is
stashed and drop it when the socket is destroyed. This guarantees that
exit information will always be recorded for the sk->sk_peer_pid task
and we can hand out pidfds for reaped processes.
Link: https://lore.kernel.org/lkml/20230807085203.819772-1-david@readahead.eu [1]
Link: https://lore.kernel.org/20250425-work-pidfs-net-v2-2-450a19461e75@kernel.org
Reviewed-by: David Rheinsberg <david@readahead.eu>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Dummy unix_unhash() was introduced for sockmap in commit 94531cfcbe
("af_unix: Add unix_stream_proto for sockmap"), but there's no need to
implement it anymore.
->unhash() is only called conditionally: in unix_shutdown() since commit
d359902d5c ("af_unix: Fix NULL pointer bug in unix_shutdown"), and in BPF
proto's sock_map_unhash() since commit 5b4a79ba65 ("bpf, sockmap: Don't
let sock_map_{close,destroy,unhash} call itself").
Remove it.
Signed-off-by: Michal Luczaj <mhal@rbox.co>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20250409-cleanup-drop-unix-unhash-v1-1-1659e5b8ee84@rbox.co
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
net/unix/*.c include many unnecessary header files (rtnetlink.h,
netdevice.h, etc).
Let's clean them up.
af_unix.c:
+uapi/linux/sockios.h : Only exist under include/uapi
+uapi/linux/termios.h : Only exist under include/uapi
-linux/freezer.h : No longer use freezable_schedule_timeout()
-linux/in.h : No ipv4_is_XXX() etc
-linux/module.h : No longer support CONFIG_UNIX=m
-linux/netdevice.h : No dev used
-linux/rtnetlink.h : Not part of rtnetlink API
-linux/signal.h : signal_pending() is defined in sched/signal.h
-linux/stat.h : No struct stat used
-net/checksum.h : CHECKSUM_UNNECESSARY is defined in skbuff.h
diag.c:
+linux/dcache.h : struct dentry in sk_diag_dump_vfs()
+linux/user_namespace.h : struct user_namespace in sk_diag_dump_uid()
+uapi/linux/unix_diag.h : Only exist under include/uapi/
garbage.c:
+linux/list.h : struct unix_{vertex,edge}, etc
+linux/workqueue.h : DECLARE_WORK(unix_gc_work, ...)
-linux/file.h : No fget() etc
-linux/kernel.h : No cond_resched() etc
-linux/netdevice.h : No dev used
-linux/proc_fs.h : No procfs provided
-linux/string.h : No memcpy(), kmemdup(), etc
sysctl_net_unix.c:
+linux/string.h : kmemdup()
+net/net_namespace.h : struct net, net_eq()
-linux/mm.h : slab.h is enough
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20250318034934.86708-5-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
include/net/af_unix.h indirectly includes some definitions for structs.
Let's include such headers explicitly.
linux/atomic.h : scm_stat.nr_fds
linux/net.h : unix_sock.peer_wq
linux/path.h : unix_sock.path
linux/spinlock.h : unix_sock.lock
linux/wait.h : unix_sock.peer_wake
uapi/linux/un.h : unix_address.name[]
linux/socket.h is removed as the structs there are not used directly,
and linux/un.h is clarified with uapi as un.h only exists under
include/uapi.
While at it, duplicate headers are removed from .c files.
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20250318034934.86708-4-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
net/af_unix.h is included by core and some LSMs, but most definitions
need not be.
Let's move struct unix_{vertex,edge} to net/unix/garbage.c and other
definitions to net/unix/af_unix.h.
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Joe Damato <jdamato@fastly.com>
Link: https://patch.msgid.link/20250318034934.86708-3-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This is a prep patch to make the following changes cleaner.
No functional change intended.
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Joe Damato <jdamato@fastly.com>
Link: https://patch.msgid.link/20250318034934.86708-2-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
After running the 'sendmsg02' program of Linux Test Project (LTP),
kmemleak reports the following memory leak:
# cat /sys/kernel/debug/kmemleak
unreferenced object 0xffff888243866800 (size 2048):
comm "sendmsg02", pid 67, jiffies 4294903166
hex dump (first 32 bytes):
00 00 00 00 00 00 00 00 5e 00 00 00 00 00 00 00 ........^.......
01 00 07 40 00 00 00 00 00 00 00 00 00 00 00 00 ...@............
backtrace (crc 7e96a3f2):
kmemleak_alloc+0x56/0x90
kmem_cache_alloc_noprof+0x209/0x450
sk_prot_alloc.constprop.0+0x60/0x160
sk_alloc+0x32/0xc0
unix_create1+0x67/0x2b0
unix_create+0x47/0xa0
__sock_create+0x12e/0x200
__sys_socket+0x6d/0x100
__x64_sys_socket+0x1b/0x30
x64_sys_call+0x7e1/0x2140
do_syscall_64+0x54/0x110
entry_SYSCALL_64_after_hwframe+0x76/0x7e
Commit 689c398885 ("af_unix: Defer sock_put() to clean up path in
unix_dgram_sendmsg().") defers sock_put() in the error handling path.
However, it fails to account for the condition 'msg->msg_namelen != 0',
resulting in a memory leak when the code jumps to the 'lookup' label.
Fix issue by calling sock_put() if 'msg->msg_namelen != 0' is met.
Fixes: 689c398885 ("af_unix: Defer sock_put() to clean up path in unix_dgram_sendmsg().")
Signed-off-by: Adrian Huang <ahuang12@lenovo.com>
Acked-by: Joe Damato <jdamato@fastly.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20250225021457.1824-1-ahuang12@lenovo.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Fix an issue with the sparse static analysis tool where an
"undefined 'other'" error occurs due to `__releases(&unix_sk(other)->lock)`
being placed before 'other' is in scope.
Remove the `__releases()` annotation from the `unix_wait_for_peer()`
function to eliminate the sparse error. The annotation references `other`
before it is declared, leading to a false positive error during static
analysis.
Since AF_UNIX does not use sparse annotations, this annotation is
unnecessary and does not impact functionality.
Reviewed-by: Joe Damato <jdamato@fastly.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: Purva Yeshi <purvayeshi550@gmail.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20250218141045.38947-1-purvayeshi550@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This is based on Donald Hunter's patch.
These functions could fail for various reasons, sometimes
triggering kfree_skb().
* unix_stream_connect() : connect()
* unix_stream_sendmsg() : sendmsg()
* queue_oob() : sendmsg(MSG_OOB)
* unix_dgram_sendmsg() : sendmsg()
Such kfree_skb() is tied to the errno of connect() and
sendmsg(), and we need not define skb drop reasons.
Let's use consume_skb() not to churn kfree_skb() events.
Link: https://lore.kernel.org/netdev/eb30b164-7f86-46bf-a5d3-0f8bda5e9398@redhat.com/
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20250116053441.5758-10-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This is a follow-up of commit d460b04bc4 ("af_unix: Clean up
error paths in unix_stream_sendmsg().").
If we initialise skb with NULL in unix_stream_sendmsg(), we can
reuse the existing out_pipe label for the SEND_SHUTDOWN check.
Let's rename it and adjust the existing label as out_pipe_lock.
While at it, size and data_len are moved to the while loop scope.
Suggested-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20250116053441.5758-9-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
unix_dgram_disconnected() is called from two places:
1. when a connect()ed socket dis-connect()s or re-connect()s to
another socket
2. when sendmsg() fails because the peer socket that the client
has connect()ed to has been close()d
Then, the client's recv queue is purged to remove all messages from
the old peer socket.
Let's define a new drop reason for that case.
# echo 1 > /sys/kernel/tracing/events/skb/kfree_skb/enable
# python3
>>> from socket import *
>>>
>>> # s1 has a message from s2
>>> s1, s2 = socketpair(AF_UNIX, SOCK_DGRAM)
>>> s2.send(b'hello world')
>>>
>>> # re-connect() drops the message from s2
>>> s3 = socket(AF_UNIX, SOCK_DGRAM)
>>> s3.bind('')
>>> s1.connect(s3.getsockname())
# cat /sys/kernel/tracing/trace_pipe
python3-250 ... kfree_skb: ... location=skb_queue_purge_reason+0xdc/0x110 reason: UNIX_DISCONNECT
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20250116053441.5758-8-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
unix_stream_read_skb() is called when BPF SOCKMAP reads some data
from a socket in the map.
SOCKMAP does not support MSG_OOB, and reading OOB results in a drop.
Let's set drop reasons respectively.
* SOCKET_CLOSE : the socket in SOCKMAP was close()d
* UNIX_SKIP_OOB : OOB was read from the socket in SOCKMAP
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20250116053441.5758-7-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
AF_UNIX SOCK_STREAM socket supports MSG_OOB.
When OOB data is sent to a socket, recv() will break at that point.
If the next recv() does not have MSG_OOB, the normal data following
the OOB data is returned.
Then, the OOB skb is dropped.
Let's define a new drop reason for that case in manage_oob().
# echo 1 > /sys/kernel/tracing/events/skb/kfree_skb/enable
# python3
>>> from socket import *
>>> s1, s2 = socketpair(AF_UNIX)
>>> s1.send(b'a', MSG_OOB)
>>> s1.send(b'b')
>>> s2.recv(2)
b'b'
# cat /sys/kernel/tracing/trace_pipe
...
python3-223 ... kfree_skb: ... location=unix_stream_read_generic+0x59e/0xc20 reason: UNIX_SKIP_OOB
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20250116053441.5758-6-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
unix_sock_destructor() is called as sk->sk_destruct() just before
the socket is actually freed.
Let's use SKB_DROP_REASON_SOCKET_CLOSE for skb_queue_purge().
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20250116053441.5758-4-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
unix_release_sock() is called when the last refcnt of struct file
is released.
Let's define a new drop reason SKB_DROP_REASON_SOCKET_CLOSE and
set it for kfree_skb() in unix_release_sock().
# echo 1 > /sys/kernel/tracing/events/skb/kfree_skb/enable
# python3
>>> from socket import *
>>> s1, s2 = socketpair(AF_UNIX)
>>> s1.send(b'hello world')
>>> s2.close()
# cat /sys/kernel/tracing/trace_pipe
...
python3-280 ... kfree_skb: ... protocol=0 location=unix_release_sock+0x260/0x420 reason: SOCKET_CLOSE
To be precise, unix_release_sock() is also called for a new child
socket in unix_stream_connect() when something fails, but the new
sk does not have skb in the recv queue then and no event is logged.
Note that only tcp_inbound_ao_hash() uses a similar drop reason,
SKB_DROP_REASON_TCP_CLOSE, and this can be generalised later.
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20250116053441.5758-3-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
unix_our_peer() is used only in unix_may_send().
Let's inline it in unix_may_send().
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
The error path is complicated in unix_dgram_sendmsg() because there
are two timings when other could be non-NULL: when it's fetched from
unix_peer_get() and when it's looked up by unix_find_other().
Let's move unix_peer_get() to the else branch for unix_find_other()
and clean up the error paths.
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
When other has SOCK_DEAD in unix_dgram_sendmsg(), we hold
unix_state_lock() for the sender socket first.
However, we do not need it for sk->sk_type.
Let's move the lock down a bit.
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
When other has SOCK_DEAD in unix_dgram_sendmsg(), we call sock_put() for
it first and then set NULL to other before jumping to the error path.
This is to skip sock_put() in the error path.
Let's not set NULL to other and defer the sock_put() to the error path
to clean up the labels later.
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
There are two paths jumping to the restart label in unix_dgram_sendmsg().
One requires another lookup and sk_filter(), but the other doesn't.
Let's split the label to make each flow more straightforward.
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
In unix_dgram_sendmsg(), we use a local variable sunaddr pointing
NULL or msg->msg_name based on msg->msg_namelen.
Let's remove sunaddr and simplify the usage.
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
When other is NULL in unix_dgram_sendmsg(), we check if sunaddr
is NULL before looking up a receiver socket.
There are three paths going through the check, but it's always
false for 2 out of the 3 paths: the first socket lookup and the
second 'goto restart'.
The condition can be true for the first 'goto restart' only when
SOCK_DEAD is flagged for the socket found with msg->msg_name.
Let's move the check to the single appropriate path.
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
We will introduce skb drop reason for AF_UNIX, then we need to
set an errno and a drop reason for each path.
Let's set an error only when it's needed in unix_dgram_sendmsg().
Then, we need not (re)set 0 to err.
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
If we move send_sig() to the SEND_SHUTDOWN check before
the while loop, then we can reuse the same kfree_skb()
after the pipe_err_free label.
Let's gather the scattered kfree_skb()s in error paths.
While at it, some style issues are fixed, and the pipe_err_free
label is renamed to out_pipe to match other label names.
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
We will introduce skb drop reason for AF_UNIX, then we need to
set an errno and a drop reason for each path.
Let's set an error only when it's needed in unix_stream_sendmsg().
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
The label order is weird in unix_stream_connect(), and all NULL checks
are unnecessary if reordered.
Let's clean up the error paths to make it easy to set a drop reason
for each path.
While at it, a comment with the old style is updated.
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
We will introduce skb drop reason for AF_UNIX, then we need to
set an errno and a drop reason for each path.
Let's set an error only when it's needed in unix_stream_connect().
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
When `skb_splice_from_iter` was introduced, it inadvertently added
checksumming for AF_UNIX sockets. This resulted in significant
slowdowns, for example when using sendfile over unix sockets.
Using the test code in [1] in my test setup (2G single core qemu),
the client receives a 1000M file in:
- without the patch: 1482ms (+/- 36ms)
- with the patch: 652.5ms (+/- 22.9ms)
This commit addresses the issue by marking checksumming as unnecessary in
`unix_stream_sendmsg`
Cc: stable@vger.kernel.org
Signed-off-by: Frederik Deweerdt <deweerdt.lkml@gmail.com>
Fixes: 2e910b9532 ("net: Add a function to splice pages into an skbuff for MSG_SPLICE_PAGES")
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Joe Damato <jdamato@fastly.com>
Link: https://patch.msgid.link/Z1fMaHkRf8cfubuE@xiberoa
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
When OOB skb has been already consumed, manage_oob() returns the next
skb if exists. In such a case, we need to fall back to the else branch
below.
Then, we want to keep holding spin_lock(&sk->sk_receive_queue.lock).
Let's move it out of if-else branch and add lightweight check before
spin_lock() for major use cases without OOB skb.
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20240905193240.17565-4-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
When OOB skb has been already consumed, manage_oob() returns the next
skb if exists. In such a case, we need to fall back to the else branch
below.
Then, we need to keep two skbs and free them later with consume_skb()
and kfree_skb().
Let's rename unlinked_skb accordingly.
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20240905193240.17565-3-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Since introduced, OOB skb holds an additional reference count with no
special reason and caused many issues.
Also, kfree_skb() and consume_skb() are used to decrement the count,
which is confusing.
Let's drop the unnecessary skb_get() in queue_oob() and corresponding
kfree_skb(), consume_skb(), and skb_unref().
Now unix_sk(sk)->oob_skb is just a pointer to skb in the receive queue,
so special handing is no longer needed in GC.
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20240816233921.57800-1-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
AF_UNIX socket tracks the most recent OOB packet (in its receive queue)
with an `oob_skb` pointer. BPF redirecting does not account for that: when
an OOB packet is moved between sockets, `oob_skb` is left outdated. This
results in a single skb that may be accessed from two different sockets.
Take the easy way out: silently drop MSG_OOB data targeting any socket that
is in a sockmap or a sockhash. Note that such silent drop is akin to the
fate of redirected skb's scm_fp_list (SCM_RIGHTS, SCM_CREDENTIALS).
For symmetry, forbid MSG_OOB in unix_bpf_recvmsg().
Fixes: 314001f0bf ("af_unix: Add OOB support")
Suggested-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: Michal Luczaj <mhal@rbox.co>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: Jakub Sitnicki <jakub@cloudflare.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Jakub Sitnicki <jakub@cloudflare.com>
Link: https://lore.kernel.org/bpf/20240713200218.2140950-2-mhal@rbox.co
Cross-merge networking fixes after downstream PR.
No conflicts.
Adjacent changes:
e3f02f32a0 ("ionic: fix kernel panic due to multi-buffer handling")
d9c0420999 ("ionic: Mark error paths in the data path as unlikely")
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Even if OOB data is recv()ed, ioctl(SIOCATMARK) must return 1 when the
OOB skb is at the head of the receive queue and no new OOB data is queued.
Without fix:
# RUN msg_oob.no_peek.oob ...
# msg_oob.c:305:oob:Expected answ[0] (0) == oob_head (1)
# oob: Test terminated by assertion
# FAIL msg_oob.no_peek.oob
not ok 2 msg_oob.no_peek.oob
With fix:
# RUN msg_oob.no_peek.oob ...
# OK msg_oob.no_peek.oob
ok 2 msg_oob.no_peek.oob
Fixes: 314001f0bf ("af_unix: Add OOB support")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Currently, recv() is stopped at a consumed OOB skb even if a new
OOB skb is queued and we can ignore the old OOB skb.
>>> from socket import *
>>> c1, c2 = socket(AF_UNIX, SOCK_STREAM)
>>> c1.send(b'hellowor', MSG_OOB)
8
>>> c2.recv(1, MSG_OOB) # consume OOB data stays at middle of recvq.
b'r'
>>> c1.send(b'ld', MSG_OOB)
2
>>> c2.recv(10) # recv() stops at the old consumed OOB
b'hellowo' # should be 'hellowol'
manage_oob() should not stop recv() at the old consumed OOB skb if
there is a new OOB data queued.
Note that TCP behaviour is apparently wrong in this test case because
we can recv() the same OOB data twice.
Without fix:
# RUN msg_oob.no_peek.ex_oob_ahead_break ...
# msg_oob.c:138:ex_oob_ahead_break:AF_UNIX :hellowo
# msg_oob.c:139:ex_oob_ahead_break:Expected:hellowol
# msg_oob.c:141:ex_oob_ahead_break:Expected ret[0] (7) == expected_len (8)
# ex_oob_ahead_break: Test terminated by assertion
# FAIL msg_oob.no_peek.ex_oob_ahead_break
not ok 11 msg_oob.no_peek.ex_oob_ahead_break
With fix:
# RUN msg_oob.no_peek.ex_oob_ahead_break ...
# msg_oob.c:146:ex_oob_ahead_break:AF_UNIX :hellowol
# msg_oob.c:147:ex_oob_ahead_break:TCP :helloworl
# OK msg_oob.no_peek.ex_oob_ahead_break
ok 11 msg_oob.no_peek.ex_oob_ahead_break
Fixes: 314001f0bf ("af_unix: Add OOB support")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Let's say a socket send()s "hello" with MSG_OOB and "world" without flags,
>>> from socket import *
>>> c1, c2 = socketpair(AF_UNIX)
>>> c1.send(b'hello', MSG_OOB)
5
>>> c1.send(b'world')
5
and its peer recv()s "hell" and "o".
>>> c2.recv(10)
b'hell'
>>> c2.recv(1, MSG_OOB)
b'o'
Now the consumed OOB skb stays at the head of recvq to return a correct
value for ioctl(SIOCATMARK), which is broken now and fixed by a later
patch.
Then, if peer issues recv() with MSG_DONTWAIT, manage_oob() returns NULL,
so recv() ends up with -EAGAIN.
>>> c2.setblocking(False) # This causes -EAGAIN even with available data
>>> c2.recv(5)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
BlockingIOError: [Errno 11] Resource temporarily unavailable
However, next recv() will return the following available data, "world".
>>> c2.recv(5)
b'world'
When the consumed OOB skb is at the head of the queue, we need to fetch
the next skb to fix the weird behaviour.
Note that the issue does not happen without MSG_DONTWAIT because we can
retry after manage_oob().
This patch also adds a test case that covers the issue.
Without fix:
# RUN msg_oob.no_peek.ex_oob_break ...
# msg_oob.c:134:ex_oob_break:AF_UNIX :Resource temporarily unavailable
# msg_oob.c:135:ex_oob_break:Expected:ld
# msg_oob.c:137:ex_oob_break:Expected ret[0] (-1) == expected_len (2)
# ex_oob_break: Test terminated by assertion
# FAIL msg_oob.no_peek.ex_oob_break
not ok 8 msg_oob.no_peek.ex_oob_break
With fix:
# RUN msg_oob.no_peek.ex_oob_break ...
# OK msg_oob.no_peek.ex_oob_break
ok 8 msg_oob.no_peek.ex_oob_break
Fixes: 314001f0bf ("af_unix: Add OOB support")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
After consuming OOB data, recv() reading the preceding data must break at
the OOB skb regardless of MSG_PEEK.
Currently, MSG_PEEK does not stop recv() for AF_UNIX, and the behaviour is
not compliant with TCP.
>>> from socket import *
>>> c1, c2 = socketpair(AF_UNIX)
>>> c1.send(b'hello', MSG_OOB)
5
>>> c1.send(b'world')
5
>>> c2.recv(1, MSG_OOB)
b'o'
>>> c2.recv(9, MSG_PEEK) # This should return b'hell'
b'hellworld' # even with enough buffer.
Let's fix it by returning NULL for consumed skb and unlinking it only if
MSG_PEEK is not specified.
This patch also adds test cases that add recv(MSG_PEEK) before each recv().
Without fix:
# RUN msg_oob.peek.oob_ahead_break ...
# msg_oob.c:134:oob_ahead_break:AF_UNIX :hellworld
# msg_oob.c:135:oob_ahead_break:Expected:hell
# msg_oob.c:137:oob_ahead_break:Expected ret[0] (9) == expected_len (4)
# oob_ahead_break: Test terminated by assertion
# FAIL msg_oob.peek.oob_ahead_break
not ok 13 msg_oob.peek.oob_ahead_break
With fix:
# RUN msg_oob.peek.oob_ahead_break ...
# OK msg_oob.peek.oob_ahead_break
ok 13 msg_oob.peek.oob_ahead_break
Fixes: 314001f0bf ("af_unix: Add OOB support")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
When (AF_UNIX, SOCK_STREAM) socket connect()s to a listening socket,
the listener's sk_peer_pid/sk_peer_cred are copied to the client in
copy_peercred().
Then, two sk_peer_locks are held there; one is client's and another
is listener's.
However, the latter is not needed because we hold the listner's
unix_state_lock() there and unix_listen() cannot update the cred
concurrently.
Let's drop the unnecessary spin_lock() and use the bare spin_lock()
for the client to protect concurrent read by getsockopt(SO_PEERCRED).
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
When (AF_UNIX, SOCK_STREAM) socket connect()s to a listening socket,
the listener's sk_peer_pid/sk_peer_cred are copied to the client in
copy_peercred().
Then, the client's sk_peer_pid and sk_peer_cred are always NULL, so
we need not call put_pid() and put_cred() there.
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
