From: Tejun Heo <tj@kernel.org>
To: torvalds@linuxfoundation.org, ebiederm@xmission.com,
mkoutny@suse.com, axboe@kernel.dk, keescook@chromium.org,
oleg@redhat.com, peterz@infradead.org, tglx@linutronix.de,
jnewsome@torproject.org, legion@kernel.org, luto@amacapital.net,
jannh@google.com
Cc: linux-kernel@vger.kernel.org, security@kernel.org, kernel-team@fb.com
Subject: [PATCHSET cgroup/for-5.16-fixes] cgroup: Use open-time creds and namespace for migration perm checks
Date: Thu, 9 Dec 2021 11:47:01 -1000 [thread overview]
Message-ID: <20211209214707.805617-1-tj@kernel.org> (raw)
Hello,
cgroup process migration permission checks are performed at write time as
whether a given operation is allowed or not is dependent on the content of
the write - the PID. This currently uses current's credentials and cgroup
namespace which is a potential security weakness as it may allow scenarios
where a less privileged process tricks a more privileged one into writing
into a fd that it created.
This patchset make the perm checks use credentials and cgroup namespace
stored at the time of open and contains the following patches.
0001-cgroup-Use-open-time-credentials-for-process-migrato.patch
0002-cgroup-Allocate-cgroup_file_ctx-for-kernfs_open_file.patch
0003-cgroup-Use-open-time-cgroup-namespace-for-process-mi.patch
0004-selftests-cgroup-Make-cg_create-use-0755-for-permiss.patch
0005-selftests-cgroup-Test-open-time-credential-usage-for.patch
0006-selftests-cgroup-Test-open-time-cgroup-namespace-usa.patch
The patchset is also available in the following git branch.
git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup.git review-migration-perms
Michal, does this also fix the original bug you were trying to fix? For now,
I didn't add Fixes / stable tags. If ppl are okay with the patchset, I'll
route it through cgroup/for-5.16-fixes.
diffstat follows. Thanks.
kernel/cgroup/cgroup-internal.h | 14 ++++
kernel/cgroup/cgroup-v1.c | 7 +-
kernel/cgroup/cgroup.c | 82 ++++++++++++++++++-------
tools/testing/selftests/cgroup/cgroup_util.c | 2
tools/testing/selftests/cgroup/test_core.c | 165 ++++++++++++++++++++++++++++++++++++++++++++++++++++
5 files changed, 244 insertions(+), 26 deletions(-)
--
tejun
next reply other threads:[~2021-12-09 21:47 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-09 21:47 Tejun Heo [this message]
2021-12-09 21:47 ` [PATCH 1/6] cgroup: Use open-time credentials for process migraton perm checks Tejun Heo
2021-12-10 17:41 ` Linus Torvalds
2021-12-09 21:47 ` [PATCH 2/6] cgroup: Allocate cgroup_file_ctx for kernfs_open_file->priv Tejun Heo
2021-12-10 17:53 ` Linus Torvalds
2021-12-10 18:38 ` Tejun Heo
2021-12-10 18:45 ` Linus Torvalds
2021-12-10 19:06 ` Tejun Heo
2021-12-10 19:14 ` Linus Torvalds
2021-12-09 21:47 ` [PATCH 3/6] cgroup: Use open-time cgroup namespace for process migration perm checks Tejun Heo
2021-12-09 21:47 ` [PATCH 4/6] selftests: cgroup: Make cg_create() use 0755 for permission instead of 0644 Tejun Heo
2021-12-09 21:47 ` [PATCH 5/6] selftests: cgroup: Test open-time credential usage for migration checks Tejun Heo
2021-12-09 21:47 ` [PATCH 6/6] selftests: cgroup: Test open-time cgroup namespace " Tejun Heo
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