From: Frederick Lawler <fred@cloudflare.com>
To: kpsingh@kernel.org, revest@chromium.org, jackmanb@chromium.org,
ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org,
kafai@fb.com, songliubraving@fb.com, yhs@fb.com,
john.fastabend@gmail.com, jmorris@namei.org, serge@hallyn.com,
paul@paul-moore.com, stephen.smalley.work@gmail.com,
eparis@parisplace.org, shuah@kernel.org, brauner@kernel.org,
casey@schaufler-ca.com, ebiederm@xmission.com,
bpf@vger.kernel.org, linux-security-module@vger.kernel.org,
selinux@vger.kernel.org, linux-kselftest@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
kernel-team@cloudflare.com, cgzones@googlemail.com,
karl@bigbadwolfsecurity.com,
Frederick Lawler <fred@cloudflare.com>
Subject: [PATCH v4 0/4] Introduce security_create_user_ns()
Date: Mon, 1 Aug 2022 13:01:42 -0500 [thread overview]
Message-ID: <20220801180146.1157914-1-fred@cloudflare.com> (raw)
While creating a LSM BPF MAC policy to block user namespace creation, we
used the LSM cred_prepare hook because that is the closest hook to prevent
a call to create_user_ns().
The calls look something like this:
cred = prepare_creds()
security_prepare_creds()
call_int_hook(cred_prepare, ...
if (cred)
create_user_ns(cred)
We noticed that error codes were not propagated from this hook and
introduced a patch [1] to propagate those errors.
The discussion notes that security_prepare_creds()
is not appropriate for MAC policies, and instead the hook is
meant for LSM authors to prepare credentials for mutation. [2]
Ultimately, we concluded that a better course of action is to introduce
a new security hook for LSM authors. [3]
This patch set first introduces a new security_create_user_ns() function
and userns_create LSM hook, then marks the hook as sleepable in BPF.
Links:
1. https://lore.kernel.org/all/20220608150942.776446-1-fred@cloudflare.com/
2. https://lore.kernel.org/all/87y1xzyhub.fsf@email.froward.int.ebiederm.org/
3. https://lore.kernel.org/all/9fe9cd9f-1ded-a179-8ded-5fde8960a586@cloudflare.com/
Past discussions:
V3: https://lore.kernel.org/all/20220721172808.585539-1-fred@cloudflare.com/
V2: https://lore.kernel.org/all/20220707223228.1940249-1-fred@cloudflare.com/
V1: https://lore.kernel.org/all/20220621233939.993579-1-fred@cloudflare.com/
Changes since v3:
- Explicitly set CAP_SYS_ADMIN to test namespace is created given
permission
- Simplify BPF test to use sleepable hook only
- Prefer unshare() over clone() for tests
Changes since v2:
- Rename create_user_ns hook to userns_create
- Use user_namespace as an object opposed to a generic namespace object
- s/domB_t/domA_t in commit message
Changes since v1:
- Add selftests/bpf: Add tests verifying bpf lsm create_user_ns hook patch
- Add selinux: Implement create_user_ns hook patch
- Change function signature of security_create_user_ns() to only take
struct cred
- Move security_create_user_ns() call after id mapping check in
create_user_ns()
- Update documentation to reflect changes
Frederick Lawler (4):
security, lsm: Introduce security_create_user_ns()
bpf-lsm: Make bpf_lsm_userns_create() sleepable
selftests/bpf: Add tests verifying bpf lsm userns_create hook
selinux: Implement userns_create hook
include/linux/lsm_hook_defs.h | 1 +
include/linux/lsm_hooks.h | 4 +
include/linux/security.h | 6 ++
kernel/bpf/bpf_lsm.c | 1 +
kernel/user_namespace.c | 5 +
security/security.c | 5 +
security/selinux/hooks.c | 9 ++
security/selinux/include/classmap.h | 2 +
.../selftests/bpf/prog_tests/deny_namespace.c | 102 ++++++++++++++++++
.../selftests/bpf/progs/test_deny_namespace.c | 33 ++++++
10 files changed, 168 insertions(+)
create mode 100644 tools/testing/selftests/bpf/prog_tests/deny_namespace.c
create mode 100644 tools/testing/selftests/bpf/progs/test_deny_namespace.c
--
2.30.2
next reply other threads:[~2022-08-01 18:02 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-01 18:01 Frederick Lawler [this message]
2022-08-01 18:01 ` [PATCH v4 1/4] security, lsm: Introduce security_create_user_ns() Frederick Lawler
2022-08-02 21:47 ` KP Singh
2022-08-03 13:13 ` Frederick Lawler
2022-08-01 18:01 ` [PATCH v4 2/4] bpf-lsm: Make bpf_lsm_userns_create() sleepable Frederick Lawler
2022-08-01 23:00 ` Alexei Starovoitov
2022-08-01 23:06 ` Paul Moore
2022-08-02 21:29 ` KP Singh
2022-08-01 18:01 ` [PATCH v4 3/4] selftests/bpf: Add tests verifying bpf lsm userns_create hook Frederick Lawler
2022-08-02 22:08 ` KP Singh
2022-08-01 18:01 ` [PATCH v4 4/4] selinux: Implement " Frederick Lawler
2022-08-02 2:56 ` [PATCH v4 0/4] Introduce security_create_user_ns() Eric W. Biederman
2022-08-03 2:10 ` Paul Moore
2022-08-08 18:56 ` Eric W. Biederman
2022-08-08 19:16 ` Paul Moore
2022-08-08 19:26 ` Eric W. Biederman
2022-08-08 19:43 ` Eric W. Biederman
2022-08-08 22:47 ` Paul Moore
2022-08-09 16:07 ` Eric W. Biederman
2022-08-09 16:47 ` Paul Moore
2022-08-09 21:40 ` Eric W. Biederman
2022-08-09 22:40 ` Paul Moore
2022-08-10 0:51 ` Alexei Starovoitov
2022-08-09 17:43 ` Casey Schaufler
2022-08-09 21:52 ` Eric W. Biederman
2022-08-08 19:49 ` Paul Moore
2022-08-09 16:40 ` Eric W. Biederman
2022-08-14 15:55 ` Serge E. Hallyn
2022-08-15 2:32 ` Paul Moore
2022-08-15 15:41 ` Serge E. Hallyn
2022-08-15 16:24 ` Paul Moore
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