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From: Casey Schaufler <casey@schaufler-ca.com>
To: Stephen Smalley <sds@tycho.nsa.gov>,
	casey.schaufler@intel.com, jmorris@namei.org,
	linux-security-module@vger.kernel.org, selinux@vger.kernel.org,
	Paul Moore <paul@paul-moore.com>
Subject: Re: [PATCH 00/90] LSM: Module stacking for all
Date: Mon, 22 Apr 2019 09:10:55 -0700	[thread overview]
Message-ID: <179fbe62-795a-564f-f8ec-26acae77685c@schaufler-ca.com> (raw)
In-Reply-To: <fc27e666-5446-08b3-48c3-a4871d06bb68@tycho.nsa.gov>

On 4/22/2019 5:46 AM, Stephen Smalley wrote:
> On 4/21/19 1:31 PM, Casey Schaufler wrote:
>> On 4/19/2019 8:27 AM, Stephen Smalley wrote:
>>> On 4/18/19 8:44 PM, Casey Schaufler wrote:
>>>> This patchset provides the changes required for
>>>> the any security module to stack safely with any other.
>>>>
>>>> A new process attribute identifies which security module
>>>> information should be reported by SO_PEERSEC and the
>>>> /proc/.../attr/current interface. This is provided by
>>>> /proc/.../attr/display. Writing the name of the security
>>>> module desired to this interface will set which LSM hooks
>>>> will be called for this information. The first security
>>>> module providing the hooks will be used by default.
>>>>
>>>> The use of integer based security tokens (secids) is
>>>> generally (but not completely) replaced by a structure
>>>> lsm_export. The lsm_export structure can contain information
>>>> for each of the security modules that export information
>>>> outside the LSM layer.
>>>>
>>>> The LSM interfaces that provide "secctx" text strings
>>>> have been changed to use a structure "lsm_context"
>>>> instead of a pointer/length pair. In some cases the
>>>> interfaces used a "char *" pointer and in others a
>>>> "void *". This was necessary to ensure that the correct
>>>> release mechanism for the text is used. It also makes
>>>> many of the interfaces cleaner.
>>>>
>>>> Security modules that use Netlabel must agree on the
>>>> labels to be used on outgoing packets. If the modules
>>>> do not agree on the label option to be used the operation
>>>> will fail.
>>>>
>>>> Netfilter secmarks are restricted to a single security
>>>> module. The first module using the facility will "own"
>>>> the secmarks.
>>>
>>> Is it expected that enabling all security modules with this change 
>>> will yield permission denials on packet send/receive (e.g. sendmsg() 
>>> fails with permission denied), even without any configuration of 
>>> NetLabel or SECMARK?  That's what I see.
>>
>> Yes.
>>
>> Smack is much more aggressive about using labeled networking
>> than SELinux. Smack tells Netlabel to label networks, whereas
>> SELinux expects them to be unlabeled. Smack has the concept of
>> an "ambient" label, which is applied to unlabeled packets, and
>> for which packets are sent unlabeled. SELinux only uses netlabel
>> for the MLS component, whereas Smack uses it for the entire
>> label. In short, it's amazing if there's a case where they do
>> agree.
>>
>> You can make the default configuration work better by specifying
>> that the Smack "floor" label be treated more like the unconfined_t.
>>
>>      # echo _ 0 0 0 > /sys/fs/smackfs/cipso2
>>      # echo NotFloor > /sys/fs/smackfs/ambient
>>
>> Will result in a situation where the two MAC systems will agree
>> much more often.
>
> Not sure that should be required given that SELinux doesn't enable 
> labeled networking at all by default,

SELinux doesn't. Smack does. Smack always enables labeled networking.


> so there is no real conflict until/unless someone configures labeled 
> networking for SELinux.

Labeled networking is independent of the security modules.
Netlabel provides mechanism and leaves policy up to whoever
might look at the lsm_secattr. Once Smack sets the default
labeling everyone get the labels.

> I'll defer to Paul on that question.
>
> Given this restriction, to what extent have you tested Smack+SELinux 
> together and what worked and didn't work? Everything except for 
> networking-related tests?

Exporting security information, either by netlabel, netfilter
secmarks or security contexts has always been the challenge.
User space has never had to deal with the possibility that
there might be more than one security module to deal with.
A system that assumes a particular security module, as do
Fedora and Ubuntu, will have some opportunities for improvement
in the full stacking world.

I have been using Fedora 29 as a primary testbed. The
Fedora user space expects SELinux and so long as SELinux
appears before Smack in the LSM list, it's happy except
for the networking. If you put Smack ahead of SELinux the
user space fails when it tries to get or set SELinux
attributes. This is because the kernel uses the first
module providing the interfaces like SO_PEERSEC, and the
code only wants to see SELinux attributes.

I'm not 100% sure I can explain the behavior of overlayfs
in the combined environment, but then I'm not sure I really
understand how it's expected to work in any case.



      reply	other threads:[~2019-04-22 16:11 UTC|newest]

Thread overview: 89+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-04-19  0:44 [PATCH 00/90] LSM: Module stacking for all Casey Schaufler
2019-04-19  0:44 ` [PATCH 01/90] LSM: Infrastructure management of the superblock Casey Schaufler
2019-04-19  0:44 ` [PATCH 02/90] LSM: Infrastructure management of the sock security Casey Schaufler
2019-04-19  0:44 ` [PATCH 03/90] LSM: Infrastructure management of the key security blob Casey Schaufler
2019-04-19  0:44 ` [PATCH 04/90] LSM: Create an lsm_export data structure Casey Schaufler
2019-04-19  0:44 ` [PATCH 05/90] LSM: Use lsm_export in the inode_getsecid hooks Casey Schaufler
2019-04-19  0:44 ` [PATCH 06/90] LSM: Use lsm_export in the cred_getsecid hooks Casey Schaufler
2019-04-19  0:44 ` [PATCH 07/90] LSM: Use lsm_export in the ipc_getsecid and task_getsecid hooks Casey Schaufler
2019-04-19  0:44 ` [PATCH 08/90] LSM: Use lsm_export in the kernel_ask_as hooks Casey Schaufler
2019-04-19  0:44 ` [PATCH 09/90] LSM: Use lsm_export in the getpeersec_dgram hooks Casey Schaufler
2019-04-19  0:44 ` [PATCH 10/90] LSM: Use lsm_export in the audit_rule_match hooks Casey Schaufler
2019-04-19  0:44 ` [PATCH 11/90] LSM: Fix logical operation in lsm_export checks Casey Schaufler
2019-04-19  0:44 ` [PATCH 12/90] LSM: Use lsm_export in the secid_to_secctx hooks Casey Schaufler
2019-04-19  0:45 ` [PATCH 13/90] LSM: Use lsm_export in the secctx_to_secid hooks Casey Schaufler
2019-04-19  0:45 ` [PATCH 14/90] LSM: Use lsm_export in security_audit_rule_match Casey Schaufler
2019-04-19  0:45 ` [PATCH 15/90] LSM: Use lsm_export in security_kernel_act_as Casey Schaufler
2019-04-19  0:45 ` [PATCH 16/90] LSM: Use lsm_export in security_socket_getpeersec_dgram Casey Schaufler
2019-04-19  0:45 ` [PATCH 17/90] LSM: Use lsm_export in security_secctx_to_secid Casey Schaufler
2019-04-19  0:45 ` [PATCH 18/90] LSM: Use lsm_export in security_secid_to_secctx Casey Schaufler
2019-04-19  0:45 ` [PATCH 19/90] LSM: Use lsm_export in security_ipc_getsecid Casey Schaufler
2019-04-19  0:45 ` [PATCH 20/90] LSM: Use lsm_export in security_task_getsecid Casey Schaufler
2019-04-19  0:45 ` [PATCH 21/90] LSM: Use lsm_export in security_inode_getsecid Casey Schaufler
2019-04-19  0:45 ` [PATCH 22/90] LSM: Use lsm_export in security_cred_getsecid Casey Schaufler
2019-04-19  0:45 ` [PATCH 23/90] Audit: Change audit_sig_sid to audit_sig_lsm Casey Schaufler
2019-04-19  0:45 ` [PATCH 24/90] Audit: Convert target_sid to an lsm_export structure Casey Schaufler
2019-04-19  0:45 ` [PATCH 25/90] Audit: Convert osid " Casey Schaufler
2019-04-19  0:45 ` [PATCH 26/90] IMA: Clean out lsm_export scaffolding Casey Schaufler
2019-04-19  0:45 ` [PATCH 27/90] NET: Change the UNIXCB from a secid to an lsm_export Casey Schaufler
2019-04-19  0:45 ` [PATCH 28/90] NET: Remove scaffolding on secmarks Casey Schaufler
2019-04-19  0:45 ` [PATCH 29/90] NET: Remove scaffolding on new secmarks Casey Schaufler
2019-04-19  0:45 ` [PATCH 30/90] NET: Remove netfilter scaffolding for lsm_export Casey Schaufler
2019-04-19  0:45 ` [PATCH 31/90] Netlabel: Replace secids with lsm_export Casey Schaufler
2019-04-19  0:45 ` [PATCH 32/90] LSM: Remove lsm_export scaffolding functions Casey Schaufler
2019-04-19  0:45 ` [PATCH 33/90] IMA: FIXUP prototype using lsm_export Casey Schaufler
2019-04-19  0:45 ` [PATCH 34/90] Smack: Restore the release_secctx hook Casey Schaufler
2019-04-19  0:45 ` [PATCH 35/90] AppArmor: Remove unnecessary hook stub Casey Schaufler
2019-04-19  0:45 ` [PATCH 36/90] LSM: Limit calls to certain module hooks Casey Schaufler
2019-04-19  0:45 ` [PATCH 37/90] LSM: Create a data structure for a security context Casey Schaufler
2019-04-19  0:45 ` [PATCH 38/90] LSM: Use lsm_context in secid_to_secctx hooks Casey Schaufler
2019-04-19  0:45 ` [PATCH 39/90] LSM: Use lsm_context in secctx_to_secid hooks Casey Schaufler
2019-04-19  0:45 ` [PATCH 40/90] LSM: Use lsm_context in inode_getsecctx hooks Casey Schaufler
2019-04-19  0:45 ` [PATCH 41/90] LSM: Use lsm_context in inode_notifysecctx hooks Casey Schaufler
2019-04-19  0:45 ` [PATCH 42/90] LSM: Use lsm_context in dentry_init_security hooks Casey Schaufler
2019-04-19  0:45 ` [PATCH 43/90] LSM: Use lsm_context in security_dentry_init_security Casey Schaufler
2019-04-19  0:45 ` [PATCH 44/90] LSM: Use lsm_context in security_inode_notifysecctx Casey Schaufler
2019-04-19  0:45 ` [PATCH 45/90] LSM: Use lsm_context in security_inode_getsecctx Casey Schaufler
2019-04-19  0:45 ` [PATCH 46/90] LSM: Use lsm_context in security_secctx_to_secid Casey Schaufler
2019-04-19  0:45 ` [PATCH 47/90] LSM: Use lsm_context in release_secctx hooks Casey Schaufler
2019-04-19  0:45 ` [PATCH 48/90] LSM: Use lsm_context in security_release_secctx Casey Schaufler
2019-04-19  0:45 ` [PATCH 49/90] LSM: Use lsm_context in security_secid_to_secctx Casey Schaufler
2019-04-19  0:45 ` [PATCH 50/90] fs: remove lsm_context scaffolding Casey Schaufler
2019-04-19  0:45 ` [PATCH 51/90] LSM: Add the release function to the lsm_context Casey Schaufler
2019-04-19  0:45 ` [PATCH 52/90] LSM: Use lsm_context in inode_setsecctx hooks Casey Schaufler
2019-04-19  0:45 ` [PATCH 53/90] LSM: Use lsm_context in security_inode_setsecctx Casey Schaufler
2019-04-19  0:45 ` [PATCH 54/90] kernfs: remove lsm_context scaffolding Casey Schaufler
2019-04-19  0:45 ` [PATCH 55/90] LSM: Remove unused macro Casey Schaufler
2019-04-19  0:45 ` [PATCH 56/90] LSM: Special handling for secctx lsm hooks Casey Schaufler
2019-04-19  0:45 ` [PATCH 57/90] SELinux: Use blob offset in current_sid Casey Schaufler
2019-04-19  0:45 ` [PATCH 58/90] LSM: Specify which LSM to display Casey Schaufler
2019-04-19  0:45 ` [PATCH 59/90] AppArmor: Remove the exclusive flag Casey Schaufler
2019-04-19  0:45 ` [PATCH 60/90] LSM: Add secmark_relabel_packet to the set of one call hooks Casey Schaufler
2019-04-19  0:45 ` [PATCH 61/90] LSM: Make getting the secmark right cleaner Casey Schaufler
2019-04-19  0:45 ` [PATCH 62/90] netfilter: Fix memory leak introduced with lsm_context Casey Schaufler
2019-04-19  0:45 ` [PATCH 63/90] Smack: Consolidate secmark conversions Casey Schaufler
2019-04-19  0:45 ` [PATCH 64/90] netfilter: Remove unnecessary NULL check in lsm_context Casey Schaufler
2019-04-19  0:45 ` [PATCH 65/90] LSM: Add secmark refcounting to call_one list Casey Schaufler
2019-04-19  0:45 ` [PATCH 66/90] LSM: refactor security_setprocattr Casey Schaufler
2019-04-19  0:45 ` [PATCH 67/90] Smack: Detect if secmarks can be safely used Casey Schaufler
2019-04-19  0:45 ` [PATCH 68/90] LSM: Support multiple LSMs using inode_init_security Casey Schaufler
2019-04-19  0:45 ` [PATCH 69/90] LSM: Use full security context in security_inode_setsecctx Casey Schaufler
2019-04-22 13:13   ` Tetsuo Handa
2019-04-22 20:45     ` Casey Schaufler
2019-04-22 21:01       ` Tetsuo Handa
2019-04-19  0:45 ` [PATCH 70/90] LSM: Correct handling of ENOSYS in inode_setxattr Casey Schaufler
2019-04-19  0:45 ` [PATCH 71/90] LSM: Infrastructure security blobs for mount options Casey Schaufler
2019-04-19  0:45 ` [PATCH 72/90] LSM: Fix for security_init_inode_security Casey Schaufler
2019-04-19  0:46 ` [PATCH 73/90] Smack: Advertise the secid to netlabel Casey Schaufler
2019-04-19  0:46 ` [PATCH 74/90] LSM: Change error detection for UDP peer security Casey Schaufler
2019-04-19  0:46 ` [PATCH 75/90] Smack: Fix setting of the CIPSO MLS_CAT flags Casey Schaufler
2019-04-19  0:46 ` [PATCH 76/90] Smack: Set netlabel flags properly on new label import Casey Schaufler
2019-04-19  0:46 ` [PATCH 77/90] Netlabel: Add a secattr comparison API function Casey Schaufler
2019-04-19  0:46 ` [PATCH 78/90] Smack: Let netlabel do the work on the ambient domain Casey Schaufler
2019-04-19  0:46 ` [PATCH 79/90] Smack: Don't set the socket label on each send Casey Schaufler
2019-04-19  0:46 ` [PATCH 80/90] Smack: Let netlabel do the work on connections Casey Schaufler
2019-04-19  0:46 ` [PATCH 81/90] Netlabel: Return the labeling type on socket Casey Schaufler
2019-04-19 15:27 ` [PATCH 00/90] LSM: Module stacking for all Stephen Smalley
2019-04-21 17:31   ` Casey Schaufler
2019-04-22 12:46     ` Stephen Smalley
2019-04-22 16:10       ` Casey Schaufler [this message]

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