From: Christian Brauner <brauner@kernel.org>
To: Stefan Berger <stefanb@linux.vnet.ibm.com>
Cc: linux-integrity@vger.kernel.org, zohar@linux.ibm.com,
serge@hallyn.com, christian.brauner@ubuntu.com,
containers@lists.linux.dev, dmitry.kasatkin@gmail.com,
ebiederm@xmission.com, krzysztof.struczynski@huawei.com,
roberto.sassu@huawei.com, mpeters@redhat.com, lhinds@redhat.com,
lsturman@redhat.com, puiterwi@redhat.com, jejb@linux.ibm.com,
jamjoom@us.ibm.com, linux-kernel@vger.kernel.org,
paul@paul-moore.com, rgb@redhat.com,
linux-security-module@vger.kernel.org, jmorris@namei.org,
Stefan Berger <stefanb@linux.ibm.com>
Subject: Re: [PATCH v9 23/23] ima: Enable IMA namespaces
Date: Wed, 26 Jan 2022 15:57:32 +0100 [thread overview]
Message-ID: <20220126145732.o3rhlay7fbsnrani@wittgenstein> (raw)
In-Reply-To: <20220125224645.79319-24-stefanb@linux.vnet.ibm.com>
On Tue, Jan 25, 2022 at 05:46:45PM -0500, Stefan Berger wrote:
> From: Stefan Berger <stefanb@linux.ibm.com>
>
> Introduce the IMA_NS in Kconfig for IMA namespace enablement.
>
> Enable the lazy initialization of an IMA namespace when a user mounts
> SecurityFS and writes '1' into IMA's 'active' securityfs file. A
> user_namespace will now get a pointer to an ima_namespace and therefore
> implement get_current_ns() for the namespacing case that returns this
> pointer. Use get_current_ns() in those places that require access to the
> current IMA namespace. In some places, primarily those related to
> IMA-appraisal and changes to file attributes, keep the pointer to
> init_ima_ns, since there flags related to file measurements may be
> affected, which are not supported in IMA namespaces, yet.
>
> Before using the ima_namespace pointer test it with ns_is_active()
> to check whether it is NULL and whether the ima_namespace is active.
> If it's not active, it cannot be used, yet. Therefore, return early
> from those functions that may now get either get a NULL pointer from
> this call or where ns->active is still 0. The init_ima_ns is always
> set to be active, thus passing the check.
>
> Implement ima_ns_from_file() for SecurityFS-related files where we can
> now get the IMA namespace via the user namespace pointer associated
> with the superblock of the SecurityFS filesystem instance.
>
> Return -EACCES to IMA's securityfs files, except for the 'active' file,
> until the IMA namespace has been set to active.
>
> Switch access to userns->ima_ns to use acquire/release semantics to ensure
> that a newly created ima_namespace structure is fully visible upon access.
>
> Only emit the kernel log message 'policy update completed' for the
> init_ima_ns.
>
> Gate access to ima_appraise variable to init_ima_ns in ima_load_data().
>
> Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
>
> ---
> v9:
> - ima_post_key_create_or_update: Only handle key if in init_ima_ns
> - Removed ns == NULL checks where user_namespace is now passed
> - Defer setting of user_ns->ima_ns until end of ima_fs_ns_init();
> required new ima_free_imans() and new user_ns_set_ima_ns()
> - Only emit log message 'policy update completed' for init_ima_ns
> - Introduce get_current_ns() only in this patch
> - Check for ns == &init_ima_ns in ima_load_data()
> ---
> include/linux/ima.h | 13 ++++
> init/Kconfig | 13 ++++
> kernel/user_namespace.c | 2 +
> security/integrity/ima/ima.h | 51 ++++++++++++--
> security/integrity/ima/ima_appraise.c | 3 +
> security/integrity/ima/ima_asymmetric_keys.c | 6 +-
> security/integrity/ima/ima_fs.c | 74 ++++++++++++++++----
> security/integrity/ima/ima_init_ima_ns.c | 2 +
> security/integrity/ima/ima_main.c | 35 +++++----
> security/integrity/ima/ima_ns.c | 15 ++--
> security/integrity/ima/ima_policy.c | 16 +++--
> 11 files changed, 188 insertions(+), 42 deletions(-)
>
> diff --git a/include/linux/ima.h b/include/linux/ima.h
> index c584527c0f47..4e595bd9733e 100644
> --- a/include/linux/ima.h
> +++ b/include/linux/ima.h
> @@ -11,6 +11,7 @@
> #include <linux/fs.h>
> #include <linux/security.h>
> #include <linux/kexec.h>
> +#include <linux/user_namespace.h>
> #include <crypto/hash_info.h>
> struct linux_binprm;
>
> @@ -68,6 +69,18 @@ static inline const char * const *arch_get_ima_policy(void)
> }
> #endif
>
> +static inline struct user_namespace
> +*ima_ns_to_user_ns(struct ima_namespace *ns)
> +{
> + struct user_namespace *user_ns;
> +
> + user_ns = current_user_ns();
> +#ifdef CONFIG_IMA_NS
> + WARN_ON(user_ns->ima_ns != ns);
> +#endif
> + return user_ns;
> +}
As I showed in [1] there are legitimate instances where ima_parse_rule()
is reached and ima->user_ns != current_user_ns(). I illustrated two
examples. So you should skip the current_user_ns() check in there.
You should be able to trigger a WARN() expanding and fixing-up the
pseudo-code of the second example in [1]. You should probably add a
test-case for this if you have test-suite already.
[1]: https://lore.kernel.org/lkml/20220114144515.vbler7ae3jqebhec@wittgenstein
next prev parent reply other threads:[~2022-01-26 14:57 UTC|newest]
Thread overview: 65+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-25 22:46 [PATCH v9 00/23] ima: Namespace IMA with audit support in IMA-ns Stefan Berger
2022-01-25 22:46 ` [PATCH v9 01/23] ima: Remove ima_policy file before directory Stefan Berger
2022-01-26 8:30 ` Christian Brauner
2022-01-25 22:46 ` [PATCH v9 02/23] ima: Do not print policy rule with inactive LSM labels Stefan Berger
2022-01-26 8:38 ` Christian Brauner
2022-01-27 14:12 ` Mimi Zohar
2022-01-25 22:46 ` [PATCH v9 03/23] securityfs: rework dentry creation Stefan Berger
2022-01-25 22:46 ` [PATCH v9 04/23] securityfs: Extend securityfs with namespacing support Stefan Berger
2022-01-27 16:53 ` Mimi Zohar
2022-01-31 22:28 ` Stefan Berger
2022-01-31 23:43 ` Mimi Zohar
2022-01-25 22:46 ` [PATCH v9 05/23] ima: Define ima_namespace struct and start moving variables into it Stefan Berger
2022-01-26 8:47 ` Christian Brauner
2022-01-25 22:46 ` [PATCH v9 06/23] ima: Move arch_policy_entry into ima_namespace Stefan Berger
2022-01-26 9:11 ` Christian Brauner
2022-01-27 19:42 ` Mimi Zohar
2022-01-25 22:46 ` [PATCH v9 07/23] ima: Move ima_htable " Stefan Berger
2022-01-26 9:16 ` Christian Brauner
2022-01-25 22:46 ` [PATCH v9 08/23] ima: Move measurement list related variables " Stefan Berger
2022-01-26 9:21 ` Christian Brauner
2022-01-26 22:23 ` Stefan Berger
2022-01-27 21:48 ` Mimi Zohar
2022-01-28 14:06 ` Stefan Berger
2022-01-25 22:46 ` [PATCH v9 09/23] ima: Move some IMA policy and filesystem " Stefan Berger
2022-01-26 9:23 ` Christian Brauner
2022-01-27 22:30 ` Mimi Zohar
2022-01-28 15:44 ` Stefan Berger
2022-01-28 16:03 ` Mimi Zohar
2022-01-25 22:46 ` [PATCH v9 10/23] ima: Move IMA securityfs files into ima_namespace or onto stack Stefan Berger
2022-01-26 9:40 ` Christian Brauner
2022-01-27 17:02 ` Stefan Berger
2022-01-28 3:13 ` Mimi Zohar
2022-01-25 22:46 ` [PATCH v9 11/23] ima: Move ima_lsm_policy_notifier into ima_namespace Stefan Berger
2022-01-26 13:05 ` Christian Brauner
2022-01-26 21:54 ` Stefan Berger
2022-01-25 22:46 ` [PATCH v9 12/23] ima: Define mac_admin_ns_capable() as a wrapper for ns_capable() Stefan Berger
2022-01-26 13:43 ` Christian Brauner
2022-01-25 22:46 ` [PATCH v9 13/23] ima: Only accept AUDIT rules for non-init_ima_ns namespaces for now Stefan Berger
2022-01-26 13:44 ` Christian Brauner
2022-01-25 22:46 ` [PATCH v9 14/23] userns: Add pointer to ima_namespace to user_namespace Stefan Berger
2022-01-26 14:46 ` Christian Brauner
2022-01-25 22:46 ` [PATCH v9 15/23] ima: Implement hierarchical processing of file accesses Stefan Berger
2022-01-26 12:39 ` Christian Brauner
2022-01-26 22:05 ` Stefan Berger
2022-01-25 22:46 ` [PATCH v9 16/23] ima: Implement ima_free_policy_rules() for freeing of an ima_namespace Stefan Berger
2022-01-28 14:02 ` Mimi Zohar
2022-01-31 18:56 ` Stefan Berger
2022-01-25 22:46 ` [PATCH v9 17/23] ima: Add functions for creating and " Stefan Berger
2022-01-26 13:56 ` Christian Brauner
2022-01-25 22:46 ` [PATCH v9 18/23] integrity/ima: Define ns_status for storing namespaced iint data Stefan Berger
2022-01-25 22:46 ` [PATCH v9 19/23] ima: Namespace audit status flags Stefan Berger
2022-01-25 22:46 ` [PATCH v9 20/23] ima: Setup securityfs for IMA namespace Stefan Berger
2022-01-26 14:03 ` Christian Brauner
2022-01-25 22:46 ` [PATCH v9 21/23] ima: Introduce securityfs file to activate an " Stefan Berger
2022-01-26 14:31 ` Christian Brauner
2022-01-27 15:24 ` Stefan Berger
2022-01-25 22:46 ` [PATCH v9 22/23] ima: Show owning user namespace's uid and gid when displaying policy Stefan Berger
2022-01-26 14:43 ` Christian Brauner
2022-01-26 14:43 ` Christian Brauner
2022-01-26 23:13 ` Stefan Berger
2022-01-25 22:46 ` [PATCH v9 23/23] ima: Enable IMA namespaces Stefan Berger
2022-01-26 14:57 ` Christian Brauner [this message]
2022-01-26 13:19 ` [PATCH v9 00/23] ima: Namespace IMA with audit support in IMA-ns Christian Brauner
2022-01-28 18:34 ` Stefan Berger
2022-01-26 16:52 ` Stefan Berger
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