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From: Casey Schaufler <casey@schaufler-ca.com>
To: "Mickaël Salaün" <mic@digikod.net>,
	casey.schaufler@intel.com, jmorris@namei.org,
	linux-security-module@vger.kernel.org, selinux@vger.kernel.org
Cc: linux-audit@redhat.com, keescook@chromium.org,
	john.johansen@canonical.com, penguin-kernel@i-love.sakura.ne.jp,
	paul@paul-moore.com, sds@tycho.nsa.gov,
	linux-kernel@vger.kernel.org, bpf@vger.kernel.org,
	Casey Schaufler <casey@schaufler-ca.com>
Subject: Re: [PATCH v26 02/25] LSM: Add the lsmblob data structure.
Date: Tue, 25 May 2021 16:52:10 -0700	[thread overview]
Message-ID: <1c3874c1-870a-ac60-03e6-2c16d49e185b@schaufler-ca.com> (raw)
In-Reply-To: <206971d6-70c7-e217-299f-1884310afa15@digikod.net>

On 5/22/2021 1:39 AM, Mickaël Salaün wrote:
> I like this design but there is an issue with Landlock though, see below.
>
> On 13/05/2021 22:07, Casey Schaufler wrote:
>> When more than one security module is exporting data to
>> audit and networking sub-systems a single 32 bit integer
>> is no longer sufficient to represent the data. Add a
>> structure to be used instead.
>>
>> The lsmblob structure is currently an array of
>> u32 "secids". There is an entry for each of the
>> security modules built into the system that would
>> use secids if active. The system assigns the module
>> a "slot" when it registers hooks. If modules are
>> compiled in but not registered there will be unused
>> slots.
>>
>> A new lsm_id structure, which contains the name
>> of the LSM and its slot number, is created. There
>> is an instance for each LSM, which assigns the name
>> and passes it to the infrastructure to set the slot.
>>
>> The audit rules data is expanded to use an array of
>> security module data rather than a single instance.
>> Because IMA uses the audit rule functions it is
>> affected as well.
>>
>> Acked-by: Stephen Smalley <sds@tycho.nsa.gov>
>> Acked-by: Paul Moore <paul@paul-moore.com>
>> Acked-by: John Johansen <john.johansen@canonical.com>
>> Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
>> Cc: <bpf@vger.kernel.org>
>> Cc: linux-audit@redhat.com
>> Cc: linux-security-module@vger.kernel.org
>> Cc: selinux@vger.kernel.org
>> To: Mimi Zohar <zohar@linux.ibm.com>
>> To: Mickaël Salaün <mic@linux.microsoft.com>
>> ---
>>  include/linux/audit.h               |  4 +-
>>  include/linux/lsm_hooks.h           | 12 ++++-
>>  include/linux/security.h            | 67 +++++++++++++++++++++++++--
>>  kernel/auditfilter.c                | 24 +++++-----
>>  kernel/auditsc.c                    | 13 +++---
>>  security/apparmor/lsm.c             |  7 ++-
>>  security/bpf/hooks.c                | 12 ++++-
>>  security/commoncap.c                |  7 ++-
>>  security/integrity/ima/ima_policy.c | 40 +++++++++++-----
>>  security/landlock/cred.c            |  2 +-
>>  security/landlock/fs.c              |  2 +-
>>  security/landlock/ptrace.c          |  2 +-
>>  security/landlock/setup.c           |  4 ++
>>  security/landlock/setup.h           |  1 +
>>  security/loadpin/loadpin.c          |  8 +++-
>>  security/lockdown/lockdown.c        |  7 ++-
>>  security/safesetid/lsm.c            |  8 +++-
>>  security/security.c                 | 72 ++++++++++++++++++++++++-----
>>  security/selinux/hooks.c            |  8 +++-
>>  security/smack/smack_lsm.c          |  7 ++-
>>  security/tomoyo/tomoyo.c            |  8 +++-
>>  security/yama/yama_lsm.c            |  7 ++-
>>  22 files changed, 262 insertions(+), 60 deletions(-)
>>
> [...]
>
>> diff --git a/security/landlock/setup.c b/security/landlock/setup.c
>> index f8e8e980454c..4a12666a4090 100644
>> --- a/security/landlock/setup.c
>> +++ b/security/landlock/setup.c
>> @@ -23,6 +23,10 @@ struct lsm_blob_sizes landlock_blob_sizes __lsm_ro_after_init = {
>>  	.lbs_superblock = sizeof(struct landlock_superblock_security),
>>  };
>>  
>> +struct lsm_id landlock_lsmid __lsm_ro_after_init = {
>> +	.lsm = LANDLOCK_NAME,
> It is missing: .slot = LSMBLOB_NEEDED,

Sorry for the delay.

Landlock does not provide any of the hooks that use a struct lsmblob.
That would be secid_to_secctx, secctx_to_secid, inode_getsecid,
cred_getsecid, kernel_act_as task_getsecid_subj task_getsecid_obj and
ipc_getsecid. Setting .slot = LSMBLOB_NEEDED indicates that the LSM
uses a slot in struct lsmblob. Landlock does not need a slot.

>
> You can run the Landlock tests please?
> make -C tools/testing/selftests TARGETS=landlock gen_tar
> tar -xf kselftest.tar.gz && ./run_kselftest.sh

Sure. I'll add them to my routine.

>
>
>> +};
>> +
>>  static int __init landlock_init(void)
>>  {
>>  	landlock_add_cred_hooks();
> [...]
>
>> diff --git a/security/security.c b/security/security.c
>> index e12a7c463468..a3276deb1b8a 100644
>> --- a/security/security.c
>> +++ b/security/security.c
>> @@ -344,6 +344,7 @@ static void __init ordered_lsm_init(void)
>>  	init_debug("sock blob size       = %d\n", blob_sizes.lbs_sock);
>>  	init_debug("superblock blob size = %d\n", blob_sizes.lbs_superblock);
>>  	init_debug("task blob size       = %d\n", blob_sizes.lbs_task);
>> +	init_debug("lsmblob size         = %zu\n", sizeof(struct lsmblob));
>>  
>>  	/*
>>  	 * Create any kmem_caches needed for blobs
>> @@ -471,21 +472,36 @@ static int lsm_append(const char *new, char **result)
>>  	return 0;
>>  }
>>  
>> +/*
>> + * Current index to use while initializing the lsmblob secid list.
>> + */
>> +static int lsm_slot __lsm_ro_after_init;
>> +
>>  /**
>>   * security_add_hooks - Add a modules hooks to the hook lists.
>>   * @hooks: the hooks to add
>>   * @count: the number of hooks to add
>> - * @lsm: the name of the security module
>> + * @lsmid: the identification information for the security module
>>   *
>>   * Each LSM has to register its hooks with the infrastructure.
>> + * If the LSM is using hooks that export secids allocate a slot
>> + * for it in the lsmblob.
>>   */
>>  void __init security_add_hooks(struct security_hook_list *hooks, int count,
>> -				char *lsm)
>> +			       struct lsm_id *lsmid)
>>  {
>>  	int i;
>>  
> Could you add a WARN_ON(!lsmid->slot || !lsmid->name) here?

Yes. That's reasonable.

>
>
>> +	if (lsmid->slot == LSMBLOB_NEEDED) {
>> +		if (lsm_slot >= LSMBLOB_ENTRIES)
>> +			panic("%s Too many LSMs registered.\n", __func__);
>> +		lsmid->slot = lsm_slot++;
>> +		init_debug("%s assigned lsmblob slot %d\n", lsmid->lsm,
>> +			   lsmid->slot);
>> +	}
>> +
>>  	for (i = 0; i < count; i++) {
>> -		hooks[i].lsm = lsm;
>> +		hooks[i].lsmid = lsmid;
>>  		hlist_add_tail_rcu(&hooks[i].list, hooks[i].head);
>>  	}
>>  


  reply	other threads:[~2021-05-25 23:52 UTC|newest]

Thread overview: 49+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20210513200807.15910-1-casey.ref@schaufler-ca.com>
2021-05-13 20:07 ` [PATCH v26 00/25] LSM: Module stacking for AppArmor Casey Schaufler
2021-05-13 20:07   ` [PATCH v26 01/25] LSM: Infrastructure management of the sock security Casey Schaufler
2021-05-13 20:07   ` [PATCH v26 02/25] LSM: Add the lsmblob data structure Casey Schaufler
2021-05-22  8:39     ` Mickaël Salaün
2021-05-25 23:52       ` Casey Schaufler [this message]
2021-05-26  9:53         ` Mickaël Salaün
2021-05-13 20:07   ` [PATCH v26 03/25] LSM: provide lsm name and id slot mappings Casey Schaufler
2021-05-14 19:00     ` Kees Cook
2021-05-21 20:18     ` Paul Moore
2021-05-13 20:07   ` [PATCH v26 04/25] IMA: avoid label collisions with stacked LSMs Casey Schaufler
2021-05-14 19:00     ` Kees Cook
2021-05-13 20:07   ` [PATCH v26 05/25] LSM: Use lsmblob in security_audit_rule_match Casey Schaufler
2021-05-13 20:07   ` [PATCH v26 06/25] LSM: Use lsmblob in security_kernel_act_as Casey Schaufler
2021-05-13 20:07   ` [PATCH v26 07/25] LSM: Use lsmblob in security_secctx_to_secid Casey Schaufler
2021-05-14 19:03     ` Kees Cook
2021-05-21 20:18     ` Paul Moore
2021-05-13 20:07   ` [PATCH v26 08/25] LSM: Use lsmblob in security_secid_to_secctx Casey Schaufler
2021-05-14 19:05     ` Kees Cook
2021-05-21 20:18     ` Paul Moore
2021-05-13 20:07   ` [PATCH v26 09/25] LSM: Use lsmblob in security_ipc_getsecid Casey Schaufler
2021-05-13 20:07   ` [PATCH v26 10/25] LSM: Use lsmblob in security_task_getsecid Casey Schaufler
2021-05-13 20:07   ` [PATCH v26 11/25] LSM: Use lsmblob in security_inode_getsecid Casey Schaufler
2021-05-13 20:07   ` [PATCH v26 12/25] LSM: Use lsmblob in security_cred_getsecid Casey Schaufler
2021-05-13 20:07   ` [PATCH v26 13/25] IMA: Change internal interfaces to use lsmblobs Casey Schaufler
2021-05-13 20:07   ` [PATCH v26 14/25] LSM: Specify which LSM to display Casey Schaufler
2021-05-14 19:23     ` Kees Cook
2021-05-17 19:52       ` Casey Schaufler
2021-05-21 20:19         ` Paul Moore
2021-05-13 20:07   ` [PATCH v26 15/25] LSM: Ensure the correct LSM context releaser Casey Schaufler
2021-05-21 20:19     ` Paul Moore
2021-05-13 20:07   ` [PATCH v26 16/25] LSM: Use lsmcontext in security_secid_to_secctx Casey Schaufler
2021-05-13 20:07   ` [PATCH v26 17/25] LSM: Use lsmcontext in security_inode_getsecctx Casey Schaufler
2021-05-14 19:24     ` Kees Cook
2021-05-13 20:08   ` [PATCH v26 18/25] LSM: security_secid_to_secctx in netlink netfilter Casey Schaufler
2021-05-21 20:19     ` Paul Moore
2021-05-13 20:08   ` [PATCH v26 19/25] NET: Store LSM netlabel data in a lsmblob Casey Schaufler
2021-05-13 20:08   ` [PATCH v26 20/25] LSM: Verify LSM display sanity in binder Casey Schaufler
2021-05-13 20:08   ` [PATCH v26 21/25] audit: add support for non-syscall auxiliary records Casey Schaufler
2021-05-21 20:19     ` Paul Moore
2021-05-13 20:08   ` [PATCH v26 22/25] Audit: Add new record for multiple process LSM attributes Casey Schaufler
2021-05-21 20:19     ` Paul Moore
2021-05-21 21:26       ` Richard Guy Briggs
2021-05-21 22:05       ` Casey Schaufler
2021-05-22  2:20         ` Paul Moore
2021-05-22 12:58           ` Richard Guy Briggs
2021-05-25 16:26       ` Casey Schaufler
2021-05-13 20:08   ` [PATCH v26 23/25] Audit: Add a new record for multiple object " Casey Schaufler
2021-05-13 20:08   ` [PATCH v26 24/25] LSM: Add /proc attr entry for full LSM context Casey Schaufler
2021-05-13 20:08   ` [PATCH v26 25/25] AppArmor: Remove the exclusive flag Casey Schaufler

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