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Connor O'Brien f1c11f7790 bpf, cgroups: Fix cgroup v2 fallback on v1/v2 mixed mode 
From: Daniel Borkmann <daniel@iogearbox.net>

commit 8520e224f547cd070c7c8f97b1fc6d58cff7ccaa upstream.

Fix cgroup v1 interference when non-root cgroup v2 BPF programs are used.
Back in the days, commit bd1060a1d671 ("sock, cgroup: add sock->sk_cgroup")
embedded per-socket cgroup information into sock->sk_cgrp_data and in order
to save 8 bytes in struct sock made both mutually exclusive, that is, when
cgroup v1 socket tagging (e.g. net_cls/net_prio) is used, then cgroup v2
falls back to the root cgroup in sock_cgroup_ptr() (&cgrp_dfl_root.cgrp).

The assumption made was "there is no reason to mix the two and this is in line
with how legacy and v2 compatibility is handled" as stated in bd1060a1d671.
However, with Kubernetes more widely supporting cgroups v2 as well nowadays,
this assumption no longer holds, and the possibility of the v1/v2 mixed mode
with the v2 root fallback being hit becomes a real security issue.

Many of the cgroup v2 BPF programs are also used for policy enforcement, just
to pick _one_ example, that is, to programmatically deny socket related system
calls like connect(2) or bind(2). A v2 root fallback would implicitly cause
a policy bypass for the affected Pods.

In production environments, we have recently seen this case due to various
circumstances: i) a different 3rd party agent and/or ii) a container runtime
such as [0] in the user's environment configuring legacy cgroup v1 net_cls
tags, which triggered implicitly mentioned root fallback. Another case is
Kubernetes projects like kind [1] which create Kubernetes nodes in a container
and also add cgroup namespaces to the mix, meaning programs which are attached
to the cgroup v2 root of the cgroup namespace get attached to a non-root
cgroup v2 path from init namespace point of view. And the latter's root is
out of reach for agents on a kind Kubernetes node to configure. Meaning, any
entity on the node setting cgroup v1 net_cls tag will trigger the bypass
despite cgroup v2 BPF programs attached to the namespace root.

Generally, this mutual exclusiveness does not hold anymore in today's user
environments and makes cgroup v2 usage from BPF side fragile and unreliable.
This fix adds proper struct cgroup pointer for the cgroup v2 case to struct
sock_cgroup_data in order to address these issues; this implicitly also fixes
the tradeoffs being made back then with regards to races and refcount leaks
as stated in bd1060a1d671, and removes the fallback, so that cgroup v2 BPF
programs always operate as expected.

  [0] https://github.com/nestybox/sysbox/
  [1] https://kind.sigs.k8s.io/

Fixes: bd1060a1d671 ("sock, cgroup: add sock->sk_cgroup")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Stanislav Fomichev <sdf@google.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/bpf/20210913230759.2313-1-daniel@iogearbox.net
[resolve trivial conflicts]
Signed-off-by: Connor O'Brien <connor.obrien@crowdstrike.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-11-23 23:20:59 +01:00
.github/workflows
android
arch KVM: arm64: Make ICC_*SGI*_EL1 undef in the absence of a vGICv3 2024-11-23 23:20:50 +01:00
block block: initialize integrity buffer to zero before writing it to media 2024-11-23 23:20:59 +01:00
certs Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
crypto crypto: aead,cipher - zeroize key buffer after use 2024-11-19 14:19:40 +01:00
Documentation hwspinlock: Introduce hwspin_lock_bust() 2024-11-23 23:20:58 +01:00
drivers drm/amd/pm: Fix the null pointer dereference for vega10_hwmgr 2024-11-23 23:20:59 +01:00
firmware/tsp_goodix Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
fs fsnotify: clear PARENT_WATCHED flags lazily 2024-11-23 23:20:58 +01:00
gki
include bpf, cgroups: Fix cgroup v2 fallback on v1/v2 mixed mode 2024-11-23 23:20:59 +01:00
init
io_uring
ipc ipc: replace costly bailout check in sysvipc_find_ipc() 2024-11-23 23:20:53 +01:00
kernel bpf, cgroups: Fix cgroup v2 fallback on v1/v2 mixed mode 2024-11-23 23:20:59 +01:00
kernel_build
KernelSU@b766b98513
kunitconfigs
lib bitmap: introduce generic optimized bitmap_size() 2024-11-23 23:20:42 +01:00
LICENSES
mm memcg_write_event_control(): fix a user-triggerable oops 2024-11-23 23:20:43 +01:00
net bpf, cgroups: Fix cgroup v2 fallback on v1/v2 mixed mode 2024-11-23 23:20:59 +01:00
samples Add gitignore file for samples/fanotify/ subdirectory 2024-11-23 23:20:30 +01:00
scripts kbuild: Fix '-S -c' in x86 stack protector scripts 2024-11-23 23:20:14 +01:00
security smack: tcp: ipv4, fix incorrect labeling 2024-11-23 23:20:58 +01:00
sound ALSA: hda/conexant: Mute speakers at suspend / shutdown 2024-11-23 23:20:56 +01:00
test
tools tools: move alignment-related macros to new <linux/align.h> 2024-11-23 23:20:50 +01:00
usr
virt
build.config.aarch64
build.config.allmodconfig Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
build.config.allmodconfig.aarch64 Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
build.config.allmodconfig.arm
build.config.allmodconfig.x86_64
build.config.amlogic
build.config.arm Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
build.config.common Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
build.config.db845c
build.config.erd8825_a25_s
build.config.erd8825_s
build.config.erd9925_evt0_s
build.config.erd9925_evt0_s5300_s
build.config.erd9925_s
build.config.gki
build.config.gki-debug.aarch64
build.config.gki-debug.x86_64
build.config.gki.aarch64
build.config.gki.aarch64.fips140
build.config.gki.aarch64.fips140_eval_testing
build.config.gki.x86_64
build.config.gki_kasan Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
build.config.gki_kasan.aarch64
build.config.gki_kasan.x86_64 Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
build.config.gki_kprobes
build.config.gki_kprobes.aarch64
build.config.gki_kprobes.x86_64
build.config.hikey960 Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
build.config.khwasan
build.config.mcd
build.config.rockchip
build.config.universal2100_s
build.config.universal8825_s
build.config.universal9925_evt0_s
build.config.universal9925_s
build.config.x86_64 Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
build.sh
COPYING
CREDITS
Kbuild Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
Kconfig
linux-stable.sh
MAINTAINERS
Makefile Linux 5.10.225 2024-11-23 23:20:56 +01:00
OWNERS
README
README.md
vendor_boot_module_order_exynos2100.cfg
vendor_boot_module_order_s5e8825.cfg
vendor_boot_module_order_s5e9925.cfg
vendor_module_list_s5e8825.cfg
vendor_module_list_s5e9925.cfg
vendor_module_list_s5e9925_b0s.cfg
vendor_module_list_s5e9925_g0s.cfg Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
vendor_module_list_s5e9925_r0s.cfg

README.md

How do I submit patches to Android Common Kernels

  1. BEST: Make all of your changes to upstream Linux. If appropriate, backport to the stable releases. These patches will be merged automatically in the corresponding common kernels. If the patch is already in upstream Linux, post a backport of the patch that conforms to the patch requirements below.

    • Do not send patches upstream that contain only symbol exports. To be considered for upstream Linux, additions of EXPORT_SYMBOL_GPL() require an in-tree modular driver that uses the symbol -- so include the new driver or changes to an existing driver in the same patchset as the export.
    • When sending patches upstream, the commit message must contain a clear case for why the patch is needed and beneficial to the community. Enabling out-of-tree drivers or functionality is not not a persuasive case.

  2. LESS GOOD: Develop your patches out-of-tree (from an upstream Linux point-of-view). Unless these are fixing an Android-specific bug, these are very unlikely to be accepted unless they have been coordinated with kernel-team@android.com. If you want to proceed, post a patch that conforms to the patch requirements below.

Common Kernel patch requirements

  • All patches must conform to the Linux kernel coding standards and pass script/checkpatch.pl
  • Patches shall not break gki_defconfig or allmodconfig builds for arm, arm64, x86, x86_64 architectures (see https://source.android.com/setup/build/building-kernels)
  • If the patch is not merged from an upstream branch, the subject must be tagged with the type of patch: UPSTREAM:, BACKPORT:, FROMGIT:, FROMLIST:, or ANDROID:.
  • All patches must have a Change-Id: tag (see https://gerrit-review.googlesource.com/Documentation/user-changeid.html)
  • If an Android bug has been assigned, there must be a Bug: tag.
  • All patches must have a Signed-off-by: tag by the author and the submitter

Additional requirements are listed below based on patch type

Requirements for backports from mainline Linux: UPSTREAM:, BACKPORT:

  • If the patch is a cherry-pick from Linux mainline with no changes at all
    • tag the patch subject with UPSTREAM:.
    • add upstream commit information with a (cherry picked from commit ...) line
    • Example:
      • if the upstream commit message is
        important patch from upstream

        This is the detailed description of the important patch

        Signed-off-by: Fred Jones <fred.jones@foo.org>
  • then Joe Smith would upload the patch for the common kernel as
        UPSTREAM: important patch from upstream

        This is the detailed description of the important patch

        Signed-off-by: Fred Jones <fred.jones@foo.org>

        Bug: 135791357
        Change-Id: I4caaaa566ea080fa148c5e768bb1a0b6f7201c01
        (cherry picked from commit c31e73121f4c1ec41143423ac6ce3ce6dafdcec1)
        Signed-off-by: Joe Smith <joe.smith@foo.org>
  • If the patch requires any changes from the upstream version, tag the patch with BACKPORT: instead of UPSTREAM:.
    • use the same tags as UPSTREAM:
    • add comments about the changes under the (cherry picked from commit ...) line
    • Example:
        BACKPORT: important patch from upstream

        This is the detailed description of the important patch

        Signed-off-by: Fred Jones <fred.jones@foo.org>

        Bug: 135791357
        Change-Id: I4caaaa566ea080fa148c5e768bb1a0b6f7201c01
        (cherry picked from commit c31e73121f4c1ec41143423ac6ce3ce6dafdcec1)
        [joe: Resolved minor conflict in drivers/foo/bar.c ]
        Signed-off-by: Joe Smith <joe.smith@foo.org>

Requirements for other backports: FROMGIT:, FROMLIST:,

  • If the patch has been merged into an upstream maintainer tree, but has not yet been merged into Linux mainline
    • tag the patch subject with FROMGIT:
    • add info on where the patch came from as (cherry picked from commit <sha1> <repo> <branch>). This must be a stable maintainer branch (not rebased, so don't use linux-next for example).
    • if changes were required, use BACKPORT: FROMGIT:
    • Example:
      • if the commit message in the maintainer tree is
        important patch from upstream

        This is the detailed description of the important patch

        Signed-off-by: Fred Jones <fred.jones@foo.org>
  • then Joe Smith would upload the patch for the common kernel as
        FROMGIT: important patch from upstream

        This is the detailed description of the important patch

        Signed-off-by: Fred Jones <fred.jones@foo.org>

        Bug: 135791357
        (cherry picked from commit 878a2fd9de10b03d11d2f622250285c7e63deace
         https://git.kernel.org/pub/scm/linux/kernel/git/foo/bar.git test-branch)
        Change-Id: I4caaaa566ea080fa148c5e768bb1a0b6f7201c01
        Signed-off-by: Joe Smith <joe.smith@foo.org>
  • If the patch has been submitted to LKML, but not accepted into any maintainer tree
    • tag the patch subject with FROMLIST:
    • add a Link: tag with a link to the submittal on lore.kernel.org
    • add a Bug: tag with the Android bug (required for patches not accepted into a maintainer tree)
    • if changes were required, use BACKPORT: FROMLIST:
    • Example:
        FROMLIST: important patch from upstream

        This is the detailed description of the important patch

        Signed-off-by: Fred Jones <fred.jones@foo.org>

        Bug: 135791357
        Link: https://lore.kernel.org/lkml/20190619171517.GA17557@someone.com/
        Change-Id: I4caaaa566ea080fa148c5e768bb1a0b6f7201c01
        Signed-off-by: Joe Smith <joe.smith@foo.org>

Requirements for Android-specific patches: ANDROID:

  • If the patch is fixing a bug to Android-specific code
    • tag the patch subject with ANDROID:
    • add a Fixes: tag that cites the patch with the bug
    • Example:
        ANDROID: fix android-specific bug in foobar.c

        This is the detailed description of the important fix

        Fixes: 1234abcd2468 ("foobar: add cool feature")
        Change-Id: I4caaaa566ea080fa148c5e768bb1a0b6f7201c01
        Signed-off-by: Joe Smith <joe.smith@foo.org>
  • If the patch is a new feature
    • tag the patch subject with ANDROID:
    • add a Bug: tag with the Android bug (required for android-specific features)