linux-stable.git/tools/include/uapi, branch linux-6.14.y Linux kernel stable tree bpf: Allow pre-ordering for bpf cgroup progs 2025-05-29T09:12:41+00:00 Yonghong Song yonghong.song@linux.dev 2025-02-24T23:01:16+00:00 4707ad649cf662add3058bff47430817811b048d [ Upstream commit 4b82b181a26cff8bf7adc3a85a88d121d92edeaf ] Currently for bpf progs in a cgroup hierarchy, the effective prog array is computed from bottom cgroup to upper cgroups (post-ordering). For example, the following cgroup hierarchy root cgroup: p1, p2 subcgroup: p3, p4 have BPF_F_ALLOW_MULTI for both cgroup levels. The effective cgroup array ordering looks like p3 p4 p1 p2 and at run time, progs will execute based on that order. But in some cases, it is desirable to have root prog executes earlier than children progs (pre-ordering). For example, - prog p1 intends to collect original pkt dest addresses. - prog p3 will modify original pkt dest addresses to a proxy address for security reason. The end result is that prog p1 gets proxy address which is not what it wants. Putting p1 to every child cgroup is not desirable either as it will duplicate itself in many child cgroups. And this is exactly a use case we are encountering in Meta. To fix this issue, let us introduce a flag BPF_F_PREORDER. If the flag is specified at attachment time, the prog has higher priority and the ordering with that flag will be from top to bottom (pre-ordering). For example, in the above example, root cgroup: p1, p2 subcgroup: p3, p4 Let us say p2 and p4 are marked with BPF_F_PREORDER. The final effective array ordering will be p2 p4 p3 p1 Suggested-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Yonghong Song <yonghong.song@linux.dev> Link: https://lore.kernel.org/r/20250224230116.283071-1-yonghong.song@linux.dev Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 4b82b181a26cff8bf7adc3a85a88d121d92edeaf ]

Currently for bpf progs in a cgroup hierarchy, the effective prog array
is computed from bottom cgroup to upper cgroups (post-ordering). For
example, the following cgroup hierarchy
    root cgroup: p1, p2
        subcgroup: p3, p4
have BPF_F_ALLOW_MULTI for both cgroup levels.
The effective cgroup array ordering looks like
    p3 p4 p1 p2
and at run time, progs will execute based on that order.

But in some cases, it is desirable to have root prog executes earlier than
children progs (pre-ordering). For example,
  - prog p1 intends to collect original pkt dest addresses.
  - prog p3 will modify original pkt dest addresses to a proxy address for
    security reason.
The end result is that prog p1 gets proxy address which is not what it
wants. Putting p1 to every child cgroup is not desirable either as it
will duplicate itself in many child cgroups. And this is exactly a use case
we are encountering in Meta.

To fix this issue, let us introduce a flag BPF_F_PREORDER. If the flag
is specified at attachment time, the prog has higher priority and the
ordering with that flag will be from top to bottom (pre-ordering).
For example, in the above example,
    root cgroup: p1, p2
        subcgroup: p3, p4
Let us say p2 and p4 are marked with BPF_F_PREORDER. The final
effective array ordering will be
    p2 p4 p3 p1

Suggested-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20250224230116.283071-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
xsk: Add launch time hardware offload support to XDP Tx metadata 2025-04-10T12:44:39+00:00 Song Yoong Siang yoong.siang.song@intel.com 2025-02-16T09:34:26+00:00 d9d736c416c9a85f84e15435ba82a177262e745b [ Upstream commit ca4419f15abd19ba8be1e109661b60f9f5b6c9f0 ] Extend the XDP Tx metadata framework so that user can requests launch time hardware offload, where the Ethernet device will schedule the packet for transmission at a pre-determined time called launch time. The value of launch time is communicated from user space to Ethernet driver via launch_time field of struct xsk_tx_metadata. Suggested-by: Stanislav Fomichev <sdf@fomichev.me> Signed-off-by: Song Yoong Siang <yoong.siang.song@intel.com> Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org> Acked-by: Stanislav Fomichev <sdf@fomichev.me> Acked-by: Jakub Kicinski <kuba@kernel.org> Link: https://patch.msgid.link/20250216093430.957880-2-yoong.siang.song@intel.com Stable-dep-of: d931cf9b38da ("igc: Fix TX drops in XDP ZC") Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit ca4419f15abd19ba8be1e109661b60f9f5b6c9f0 ]

Extend the XDP Tx metadata framework so that user can requests launch time
hardware offload, where the Ethernet device will schedule the packet for
transmission at a pre-determined time called launch time. The value of
launch time is communicated from user space to Ethernet driver via
launch_time field of struct xsk_tx_metadata.

Suggested-by: Stanislav Fomichev <sdf@fomichev.me>
Signed-off-by: Song Yoong Siang <yoong.siang.song@intel.com>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Acked-by: Stanislav Fomichev <sdf@fomichev.me>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Link: https://patch.msgid.link/20250216093430.957880-2-yoong.siang.song@intel.com
Stable-dep-of: d931cf9b38da ("igc: Fix TX drops in XDP ZC")
Signed-off-by: Sasha Levin <sashal@kernel.org>
tools headers: Sync uapi/asm-generic/socket.h with the kernel sources 2025-03-20T14:14:46+00:00 Alexander Mikhalitsyn aleksandr.mikhalitsyn@canonical.com 2025-03-14T21:41:54+00:00 23b763302ce068d7c97441e75434dc9f903adc7d This also fixes a wrong definitions for SCM_TS_OPT_ID & SO_RCVPRIORITY. Accidentally found while working on another patchset. Cc: linux-kernel@vger.kernel.org Cc: netdev@vger.kernel.org Cc: Eric Dumazet <edumazet@google.com> Cc: Jakub Kicinski <kuba@kernel.org> Cc: Vadim Fedorenko <vadim.fedorenko@linux.dev> Cc: Willem de Bruijn <willemb@google.com> Cc: Jason Xing <kerneljasonxing@gmail.com> Cc: Anna Emese Nyiri <annaemesenyiri@gmail.com> Cc: Kuniyuki Iwashima <kuniyu@amazon.com> Cc: Paolo Abeni <pabeni@redhat.com> Fixes: a89568e9be75 ("selftests: txtimestamp: add SCM_TS_OPT_ID test") Fixes: e45469e594b2 ("sock: Introduce SO_RCVPRIORITY socket option") Link: https://lore.kernel.org/netdev/20250314195257.34854-1-kuniyu@amazon.com/ Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com> Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com> Reviewed-by: Willem de Bruijn <willemb@google.com> Reviewed-by: Jason Xing <kerneljasonxing@gmail.com> Link: https://patch.msgid.link/20250314214155.16046-1-aleksandr.mikhalitsyn@canonical.com Signed-off-by: Paolo Abeni <pabeni@redhat.com> 
This also fixes a wrong definitions for SCM_TS_OPT_ID & SO_RCVPRIORITY.

Accidentally found while working on another patchset.

Cc: linux-kernel@vger.kernel.org
Cc: netdev@vger.kernel.org
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Vadim Fedorenko <vadim.fedorenko@linux.dev>
Cc: Willem de Bruijn <willemb@google.com>
Cc: Jason Xing <kerneljasonxing@gmail.com>
Cc: Anna Emese Nyiri <annaemesenyiri@gmail.com>
Cc: Kuniyuki Iwashima <kuniyu@amazon.com>
Cc: Paolo Abeni <pabeni@redhat.com>
Fixes: a89568e9be75 ("selftests: txtimestamp: add SCM_TS_OPT_ID test")
Fixes: e45469e594b2 ("sock: Introduce SO_RCVPRIORITY socket option")
Link: https://lore.kernel.org/netdev/20250314195257.34854-1-kuniyu@amazon.com/
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Reviewed-by: Jason Xing <kerneljasonxing@gmail.com>
Link: https://patch.msgid.link/20250314214155.16046-1-aleksandr.mikhalitsyn@canonical.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Merge tag 'bpf-next-6.14' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2025-01-23T16:04:07+00:00 Linus Torvalds torvalds@linux-foundation.org 2025-01-23T16:04:07+00:00 d0d106a2bd21499901299160744e5fe9f4c83ddb Pull bpf updates from Alexei Starovoitov: "A smaller than usual release cycle. The main changes are: - Prepare selftest to run with GCC-BPF backend (Ihor Solodrai) In addition to LLVM-BPF runs the BPF CI now runs GCC-BPF in compile only mode. Half of the tests are failing, since support for btf_decl_tag is still WIP, but this is a great milestone. - Convert various samples/bpf to selftests/bpf/test_progs format (Alexis Lothoré and Bastien Curutchet) - Teach verifier to recognize that array lookup with constant in-range index will always succeed (Daniel Xu) - Cleanup migrate disable scope in BPF maps (Hou Tao) - Fix bpf_timer destroy path in PREEMPT_RT (Hou Tao) - Always use bpf_mem_alloc in bpf_local_storage in PREEMPT_RT (Martin KaFai Lau) - Refactor verifier lock support (Kumar Kartikeya Dwivedi) This is a prerequisite for upcoming resilient spin lock. - Remove excessive 'may_goto +0' instructions in the verifier that LLVM leaves when unrolls the loops (Yonghong Song) - Remove unhelpful bpf_probe_write_user() warning message (Marco Elver) - Add fd_array_cnt attribute for prog_load command (Anton Protopopov) This is a prerequisite for upcoming support for static_branch" * tag 'bpf-next-6.14' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (125 commits) selftests/bpf: Add some tests related to 'may_goto 0' insns bpf: Remove 'may_goto 0' instruction in opt_remove_nops() bpf: Allow 'may_goto 0' instruction in verifier selftests/bpf: Add test case for the freeing of bpf_timer bpf: Cancel the running bpf_timer through kworker for PREEMPT_RT bpf: Free element after unlock in __htab_map_lookup_and_delete_elem() bpf: Bail out early in __htab_map_lookup_and_delete_elem() bpf: Free special fields after unlock in htab_lru_map_delete_node() tools: Sync if_xdp.h uapi tooling header libbpf: Work around kernel inconsistently stripping '.llvm.' suffix bpf: selftests: verifier: Add nullness elision tests bpf: verifier: Support eliding map lookup nullness bpf: verifier: Refactor helper access type tracking bpf: tcp: Mark bpf_load_hdr_opt() arg2 as read-write bpf: verifier: Add missing newline on verbose() call selftests/bpf: Add distilled BTF test about marking BTF_IS_EMBEDDED libbpf: Fix incorrect traversal end type ID when marking BTF_IS_EMBEDDED libbpf: Fix return zero when elf_begin failed selftests/bpf: Fix btf leak on new btf alloc failure in btf_distill test veristat: Load struct_ops programs only once ... 
Pull bpf updates from Alexei Starovoitov:
 "A smaller than usual release cycle.

  The main changes are:

   - Prepare selftest to run with GCC-BPF backend (Ihor Solodrai)

     In addition to LLVM-BPF runs the BPF CI now runs GCC-BPF in compile
     only mode. Half of the tests are failing, since support for
     btf_decl_tag is still WIP, but this is a great milestone.

   - Convert various samples/bpf to selftests/bpf/test_progs format
     (Alexis Lothoré and Bastien Curutchet)

   - Teach verifier to recognize that array lookup with constant
     in-range index will always succeed (Daniel Xu)

   - Cleanup migrate disable scope in BPF maps (Hou Tao)

   - Fix bpf_timer destroy path in PREEMPT_RT (Hou Tao)

   - Always use bpf_mem_alloc in bpf_local_storage in PREEMPT_RT (Martin
     KaFai Lau)

   - Refactor verifier lock support (Kumar Kartikeya Dwivedi)

     This is a prerequisite for upcoming resilient spin lock.

   - Remove excessive 'may_goto +0' instructions in the verifier that
     LLVM leaves when unrolls the loops (Yonghong Song)

   - Remove unhelpful bpf_probe_write_user() warning message (Marco
     Elver)

   - Add fd_array_cnt attribute for prog_load command (Anton Protopopov)

     This is a prerequisite for upcoming support for static_branch"

* tag 'bpf-next-6.14' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (125 commits)
  selftests/bpf: Add some tests related to 'may_goto 0' insns
  bpf: Remove 'may_goto 0' instruction in opt_remove_nops()
  bpf: Allow 'may_goto 0' instruction in verifier
  selftests/bpf: Add test case for the freeing of bpf_timer
  bpf: Cancel the running bpf_timer through kworker for PREEMPT_RT
  bpf: Free element after unlock in __htab_map_lookup_and_delete_elem()
  bpf: Bail out early in __htab_map_lookup_and_delete_elem()
  bpf: Free special fields after unlock in htab_lru_map_delete_node()
  tools: Sync if_xdp.h uapi tooling header
  libbpf: Work around kernel inconsistently stripping '.llvm.' suffix
  bpf: selftests: verifier: Add nullness elision tests
  bpf: verifier: Support eliding map lookup nullness
  bpf: verifier: Refactor helper access type tracking
  bpf: tcp: Mark bpf_load_hdr_opt() arg2 as read-write
  bpf: verifier: Add missing newline on verbose() call
  selftests/bpf: Add distilled BTF test about marking BTF_IS_EMBEDDED
  libbpf: Fix incorrect traversal end type ID when marking BTF_IS_EMBEDDED
  libbpf: Fix return zero when elf_begin failed
  selftests/bpf: Fix btf leak on new btf alloc failure in btf_distill test
  veristat: Load struct_ops programs only once
  ...
tools: Sync if_xdp.h uapi tooling header 2025-01-17T14:49:16+00:00 Vishal Chourasia vishalc@linux.ibm.com 2025-01-17T14:42:59+00:00 01f3ce5328c405179b2c69ea047c423dad2bfa6d Sync if_xdp.h uapi header to remove following warning: Warning: Kernel ABI header at 'tools/include/uapi/linux/if_xdp.h' differs from latest version at 'include/uapi/linux/if_xdp.h' Fixes: 48eb03dd2630 ("xsk: Add TX timestamp and TX checksum offload support") Signed-off-by: Vishal Chourasia <vishalc@linux.ibm.com> Signed-off-by: Song Yoong Siang <yoong.siang.song@intel.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20250115032248.125742-1-yoong.siang.song@intel.com 
Sync if_xdp.h uapi header to remove following warning:

  Warning: Kernel ABI header at 'tools/include/uapi/linux/if_xdp.h'
  differs from latest version at 'include/uapi/linux/if_xdp.h'

Fixes: 48eb03dd2630 ("xsk: Add TX timestamp and TX checksum offload support")
Signed-off-by: Vishal Chourasia <vishalc@linux.ibm.com>
Signed-off-by: Song Yoong Siang <yoong.siang.song@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20250115032248.125742-1-yoong.siang.song@intel.com
Merge tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2025-01-07T23:39:09+00:00 Jakub Kicinski kuba@kernel.org 2025-01-07T23:39:09+00:00 a8a6531164e54cea6df4d82f1770451f68945972 Daniel Borkmann says: ==================== pull-request: bpf-next 2025-01-07 We've added 7 non-merge commits during the last 32 day(s) which contain a total of 11 files changed, 190 insertions(+), 103 deletions(-). The main changes are: 1) Migrate the test_xdp_meta.sh BPF selftest into test_progs framework, from Bastien Curutchet. 2) Add ability to configure head/tailroom for netkit devices, from Daniel Borkmann. 3) Fixes and improvements to the xdp_hw_metadata selftest, from Song Yoong Siang. * tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: selftests/bpf: Extend netkit tests to validate set {head,tail}room netkit: Add add netkit {head,tail}room to rt_link.yaml netkit: Allow for configuring needed_{head,tail}room selftests/bpf: Migrate test_xdp_meta.sh into xdp_context_test_run.c selftests/bpf: test_xdp_meta: Rename BPF sections selftests/bpf: Enable Tx hwtstamp in xdp_hw_metadata selftests/bpf: Actuate tx_metadata_len in xdp_hw_metadata ==================== Link: https://patch.msgid.link/20250107130908.143644-1-daniel@iogearbox.net Signed-off-by: Jakub Kicinski <kuba@kernel.org> 
Daniel Borkmann says:

====================
pull-request: bpf-next 2025-01-07

We've added 7 non-merge commits during the last 32 day(s) which contain
a total of 11 files changed, 190 insertions(+), 103 deletions(-).

The main changes are:

1) Migrate the test_xdp_meta.sh BPF selftest into test_progs
   framework, from Bastien Curutchet.

2) Add ability to configure head/tailroom for netkit devices,
   from Daniel Borkmann.

3) Fixes and improvements to the xdp_hw_metadata selftest,
   from Song Yoong Siang.

* tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next:
  selftests/bpf: Extend netkit tests to validate set {head,tail}room
  netkit: Add add netkit {head,tail}room to rt_link.yaml
  netkit: Allow for configuring needed_{head,tail}room
  selftests/bpf: Migrate test_xdp_meta.sh into xdp_context_test_run.c
  selftests/bpf: test_xdp_meta: Rename BPF sections
  selftests/bpf: Enable Tx hwtstamp in xdp_hw_metadata
  selftests/bpf: Actuate tx_metadata_len in xdp_hw_metadata
====================

Link: https://patch.msgid.link/20250107130908.143644-1-daniel@iogearbox.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
netkit: Allow for configuring needed_{head,tail}room 2025-01-06T08:48:49+00:00 Daniel Borkmann daniel@iogearbox.net 2024-12-20T23:46:56+00:00 b9ed315d3c4c0c294a4348edb6874d489bac47fa Allow the user to configure needed_{head,tail}room for both netkit devices. The idea is similar to 163e529200af ("veth: implement ndo_set_rx_headroom") with the difference that the two parameters can be specified upon device creation. By default the current behavior stays as is which is needed_{head,tail}room is 0. In case of Cilium, for example, the netkit devices are not enslaved into a bridge or openvswitch device (rather, BPF-based redirection is used out of tcx), and as such these parameters are not propagated into the Pod's netns via peer device. Given Cilium can run in vxlan/geneve tunneling mode (needed_headroom) and/or be used in combination with WireGuard (needed_{head,tail}room), allow the Cilium CNI plugin to specify these two upon netkit device creation. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: Jakub Kicinski <kuba@kernel.org> Acked-by: Nikolay Aleksandrov <razor@blackwall.org> Link: https://lore.kernel.org/bpf/20241220234658.490686-1-daniel@iogearbox.net 
Allow the user to configure needed_{head,tail}room for both netkit
devices. The idea is similar to 163e529200af ("veth: implement
ndo_set_rx_headroom") with the difference that the two parameters
can be specified upon device creation. By default the current behavior
stays as is which is needed_{head,tail}room is 0.

In case of Cilium, for example, the netkit devices are not enslaved
into a bridge or openvswitch device (rather, BPF-based redirection
is used out of tcx), and as such these parameters are not propagated
into the Pod's netns via peer device.

Given Cilium can run in vxlan/geneve tunneling mode (needed_headroom)
and/or be used in combination with WireGuard (needed_{head,tail}room),
allow the Cilium CNI plugin to specify these two upon netkit device
creation.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Jakub Kicinski <kuba@kernel.org>
Acked-by: Nikolay Aleksandrov <razor@blackwall.org>
Link: https://lore.kernel.org/bpf/20241220234658.490686-1-daniel@iogearbox.net
Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2025-01-04T00:29:29+00:00 Jakub Kicinski kuba@kernel.org 2024-12-05T19:48:58+00:00 385f186aba3d2f7122b71d6d4c7e236b9d4e8003 Cross-merge networking fixes after downstream PR (net-6.13-rc6). No conflicts. Adjacent changes: include/linux/if_vlan.h f91a5b808938 ("af_packet: fix vlan_get_protocol_dgram() vs MSG_PEEK") 3f330db30638 ("net: reformat kdoc return statements") Signed-off-by: Jakub Kicinski <kuba@kernel.org> 
Cross-merge networking fixes after downstream PR (net-6.13-rc6).

No conflicts.

Adjacent changes:

include/linux/if_vlan.h
  f91a5b808938 ("af_packet: fix vlan_get_protocol_dgram() vs MSG_PEEK")
  3f330db30638 ("net: reformat kdoc return statements")

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Merge tag 'hardening-v6.13-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux 2024-12-27T18:39:05+00:00 Linus Torvalds torvalds@linux-foundation.org 2024-12-27T18:39:05+00:00 f0bc704f4688ab6625dc1226cf33338c638ae6b8 Pull hardening fix from Kees Cook: - stddef: make __struct_group() UAPI C++-friendly (Alexander Lobakin) * tag 'hardening-v6.13-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: stddef: make __struct_group() UAPI C++-friendly 
Pull hardening fix from Kees Cook:

 - stddef: make __struct_group() UAPI C++-friendly (Alexander Lobakin)

* tag 'hardening-v6.13-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  stddef: make __struct_group() UAPI C++-friendly
stddef: make __struct_group() UAPI C++-friendly 2024-12-20T17:05:53+00:00 Alexander Lobakin aleksander.lobakin@intel.com 2024-12-19T13:57:34+00:00 724c6ce38bbaeb4b3f109b0e066d6c0ecd15446c For the most part of the C++ history, it couldn't have type declarations inside anonymous unions for different reasons. At the same time, __struct_group() relies on the latters, so when the @TAG argument is not empty, C++ code doesn't want to build (even under `extern "C"`): ../linux/include/uapi/linux/pkt_cls.h:25:24: error: 'struct tc_u32_sel::<unnamed union>::tc_u32_sel_hdr,' invalid; an anonymous union may only have public non-static data members [-fpermissive] The safest way to fix this without trying to switch standards (which is impossible in UAPI anyway) etc., is to disable tag declaration for that language. This won't break anything since for now it's not buildable at all. Use a separate definition for __struct_group() when __cplusplus is defined to mitigate the error, including the version from tools/. Fixes: 50d7bd38c3aa ("stddef: Introduce struct_group() helper macro") Reported-by: Christopher Ferris <cferris@google.com> Closes: https://lore.kernel.org/linux-hardening/Z1HZpe3WE5As8UAz@google.com Suggested-by: Kees Cook <kees@kernel.org> # __struct_group_tag() Signed-off-by: Alexander Lobakin <aleksander.lobakin@intel.com> Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org> Link: https://lore.kernel.org/r/20241219135734.2130002-1-aleksander.lobakin@intel.com Signed-off-by: Kees Cook <kees@kernel.org> 
For the most part of the C++ history, it couldn't have type
declarations inside anonymous unions for different reasons. At the
same time, __struct_group() relies on the latters, so when the @TAG
argument is not empty, C++ code doesn't want to build (even under
`extern "C"`):

../linux/include/uapi/linux/pkt_cls.h:25:24: error:
'struct tc_u32_sel::<unnamed union>::tc_u32_sel_hdr,' invalid;
an anonymous union may only have public non-static data members
[-fpermissive]

The safest way to fix this without trying to switch standards (which
is impossible in UAPI anyway) etc., is to disable tag declaration
for that language. This won't break anything since for now it's not
buildable at all.
Use a separate definition for __struct_group() when __cplusplus is
defined to mitigate the error, including the version from tools/.

Fixes: 50d7bd38c3aa ("stddef: Introduce struct_group() helper macro")
Reported-by: Christopher Ferris <cferris@google.com>
Closes: https://lore.kernel.org/linux-hardening/Z1HZpe3WE5As8UAz@google.com
Suggested-by: Kees Cook <kees@kernel.org> # __struct_group_tag()
Signed-off-by: Alexander Lobakin <aleksander.lobakin@intel.com>
Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Link: https://lore.kernel.org/r/20241219135734.2130002-1-aleksander.lobakin@intel.com
Signed-off-by: Kees Cook <kees@kernel.org>