From: "Xing, Cedric" <cedric.xing@intel.com>
To: Casey Schaufler <casey@schaufler-ca.com>,
linux-sgx@vger.kernel.org, linux-security-module@vger.kernel.org,
selinux@vger.kernel.org
Subject: Re: [RFC PATCH v3 3/4] X86/sgx: Introduce EMA as a new LSM module
Date: Mon, 8 Jul 2019 10:16:56 -0700 [thread overview]
Message-ID: <ce4dcce2-88fb-ccec-f173-fc567d9ca006@intel.com> (raw)
In-Reply-To: <fb4352a4-7ef4-6824-a2ab-21e5fcb208ae@schaufler-ca.com>
On 7/8/2019 9:26 AM, Casey Schaufler wrote:
> In this scheme you use an ema LSM to manage your ema data.
> A quick sketch looks like:
>
> sgx_something_in() calls
> security_enclave_load() calls
> ema_enclave_load()
> selinux_enclave_load()
> otherlsm_enclave_load()
>
> Why is this better than:
>
> sgx_something_in() calls
> ema_enclave_load()
> security_enclave_load() calls
> selinux_enclave_load()
> otherlsm_enclave_load()
Are you talking about moving EMA somewhere outside LSM? If so, where?
>
>
> If you did really want ema to behave like an LSM
> you would put the file data that SELinux is managing
> into the ema portion of the blob and provide interfaces
> for the SELinux (or whoever) to use that. Also, it's
> an abomination (as I've stated before) for ema to
> rely on SELinux to provide a file_free() hook for
> ema's data. If you continue down the LSM route, you
> need to provide an ema_file_free() hook. You can't
> count on SELinux to do it for you. If there are multiple
> LSMs (coming soon!) that use the ema data, they'll all
> try to free it, and then Bad Things can happen.
I'm afraid you have misunderstood the code. What is kept open and gets
closed in selinux_file_free() is the sigstruct file. SELinux uses it to
determine the page permissions for enclave pages from anonymous sources.
It is a policy choice made inside SELinux and has nothing to do with EMA.
There's indeed an ema_file_free_security() to free the EMA map for
enclaves being closed. EMA does *NOT* rely on any other LSMs to free
data for it. The only exception is when an LSM fails enclave_load(), it
has to call ema_remove_range() to remove the range being added, which
was *not* required originally in v2.
>> +/**
>> + * ema - Enclave Memory Area structure for LSM modules
>
> LSM modules is redundant. "LSM" or "LSMs" would be better.
Noted
>> diff --git a/security/Makefile b/security/Makefile
>> index c598b904938f..b66d03a94853 100644
>> --- a/security/Makefile
>> +++ b/security/Makefile
>> @@ -28,6 +28,7 @@ obj-$(CONFIG_SECURITY_YAMA) += yama/
>> obj-$(CONFIG_SECURITY_LOADPIN) += loadpin/
>> obj-$(CONFIG_SECURITY_SAFESETID) += safesetid/
>> obj-$(CONFIG_CGROUP_DEVICE) += device_cgroup.o
>> +obj-$(CONFIG_INTEL_SGX) += commonema.o
>
> The config option and the file name ought to match,
> or at least be closer.
Just trying to match file names as "capability" uses commoncap.c.
Like I said, this feature could potentially be used by TEEs other than
SGX. For now, SGX is the only user so it is tied to CONFIG_INTEL_SGX. I
can rename it to ema.c or enclave.c. Do you have a preference?
>> diff --git a/security/commonema.c b/security/commonema.c
>
> Put this in a subdirectory. Please.
Then why is commoncap.c located in this directory? I'm just trying to
match the existing convention.
>> +static struct lsm_blob_sizes ema_blob_sizes __lsm_ro_after_init = {
>> + .lbs_file = sizeof(atomic_long_t),
>> +};
>
> If this is ema's data ema must manage it. You *must* have
> a file_free().
There is one indeed - ema_file_free_security().
>
>> +
>> +static atomic_long_t *_map_file(struct file *encl)
>> +{
>> + return (void *)((char *)(encl->f_security) + ema_blob_sizes.lbs_file);
>
> I don't trust all the casting going on here, especially since
> you don't end up with the type you should be returning.
Will change.
>> +}
>> +
>> +static struct ema_map *_alloc_map(void)
>
> Function header comments, please.
Will add.
next prev parent reply other threads:[~2019-07-08 17:16 UTC|newest]
Thread overview: 156+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-19 22:23 [RFC PATCH v4 00/12] security: x86/sgx: SGX vs. LSM Sean Christopherson
2019-06-19 22:23 ` [RFC PATCH v4 01/12] x86/sgx: Use mmu_notifier.release() instead of per-vma refcounting Sean Christopherson
2019-06-20 21:03 ` Jarkko Sakkinen
2019-07-08 14:57 ` Sean Christopherson
2019-07-09 16:18 ` Jarkko Sakkinen
2019-06-19 22:23 ` [RFC PATCH v4 02/12] x86/sgx: Do not naturally align MAP_FIXED address Sean Christopherson
2019-06-20 21:09 ` Jarkko Sakkinen
2019-06-20 22:09 ` Jarkko Sakkinen
2019-06-19 22:23 ` [RFC PATCH v4 03/12] selftests: x86/sgx: Mark the enclave loader as not needing an exec stack Sean Christopherson
2019-06-20 21:17 ` Jarkko Sakkinen
2019-06-19 22:23 ` [RFC PATCH v4 04/12] x86/sgx: Require userspace to define enclave pages' protection bits Sean Christopherson
2019-06-21 1:07 ` Jarkko Sakkinen
2019-06-21 1:16 ` Jarkko Sakkinen
2019-06-21 16:42 ` Xing, Cedric
2019-07-08 16:34 ` Sean Christopherson
2019-07-08 17:29 ` Xing, Cedric
2019-07-01 18:00 ` Andy Lutomirski
2019-07-01 19:22 ` Xing, Cedric
2019-06-19 22:23 ` [RFC PATCH v4 05/12] x86/sgx: Enforce noexec filesystem restriction for enclaves Sean Christopherson
2019-06-21 1:26 ` Jarkko Sakkinen
2019-07-07 19:03 ` Sean Christopherson
2019-06-19 22:23 ` [RFC PATCH v4 06/12] mm: Introduce vm_ops->may_mprotect() Sean Christopherson
2019-06-21 1:35 ` Jarkko Sakkinen
2019-06-19 22:23 ` [RFC PATCH v4 07/12] LSM: x86/sgx: Introduce ->enclave_map() hook for Intel SGX Sean Christopherson
2019-06-21 2:28 ` Jarkko Sakkinen
2019-06-21 16:54 ` Xing, Cedric
2019-06-25 20:48 ` Stephen Smalley
2019-06-27 20:29 ` Xing, Cedric
2019-07-07 18:01 ` Sean Christopherson
2019-06-19 22:23 ` [RFC PATCH v4 08/12] security/selinux: Require SGX_MAPWX to map enclave page WX Sean Christopherson
2019-06-21 17:09 ` Xing, Cedric
2019-06-25 21:05 ` Stephen Smalley
2019-06-27 20:26 ` Xing, Cedric
2019-06-25 20:19 ` Stephen Smalley
2019-06-26 12:49 ` Dr. Greg
2019-06-19 22:23 ` [RFC PATCH v4 09/12] LSM: x86/sgx: Introduce ->enclave_load() hook for Intel SGX Sean Christopherson
2019-06-21 17:05 ` Xing, Cedric
2019-06-25 21:01 ` Stephen Smalley
2019-06-25 21:49 ` Stephen Smalley
2019-06-27 19:38 ` Xing, Cedric
2019-06-19 22:23 ` [RFC PATCH v4 10/12] security/selinux: Add enclave_load() implementation Sean Christopherson
2019-06-21 21:22 ` Xing, Cedric
2019-06-25 21:09 ` Stephen Smalley
2019-06-27 20:19 ` Xing, Cedric
2019-06-28 16:16 ` Stephen Smalley
2019-06-28 21:20 ` Xing, Cedric
2019-06-29 1:15 ` Stephen Smalley
2019-07-01 18:14 ` Xing, Cedric
2019-06-29 23:41 ` Andy Lutomirski
2019-07-01 17:46 ` Xing, Cedric
2019-07-01 17:53 ` Andy Lutomirski
2019-07-01 18:54 ` Xing, Cedric
2019-07-01 19:03 ` Xing, Cedric
2019-07-01 19:32 ` Andy Lutomirski
2019-07-01 20:03 ` Xing, Cedric
2019-07-07 18:46 ` Sean Christopherson
2019-06-25 20:34 ` Stephen Smalley
2019-06-19 22:24 ` [RFC PATCH v4 11/12] security/apparmor: " Sean Christopherson
2019-06-19 22:24 ` [RFC PATCH v4 12/12] LSM: x86/sgx: Show line of sight to LSM support SGX2's EAUG Sean Christopherson
2019-06-21 17:18 ` Xing, Cedric
2019-07-08 14:34 ` Sean Christopherson
2019-06-21 1:32 ` [RFC PATCH v4 00/12] security: x86/sgx: SGX vs. LSM Jarkko Sakkinen
2019-06-27 18:56 ` [RFC PATCH v2 0/3] security/x86/sgx: SGX specific LSM hooks Cedric Xing
2019-07-03 23:16 ` Jarkko Sakkinen
2019-07-03 23:22 ` Jarkko Sakkinen
2019-07-03 23:23 ` Jarkko Sakkinen
2019-07-06 5:04 ` Xing, Cedric
2019-07-08 14:46 ` Jarkko Sakkinen
2019-07-07 23:41 ` [RFC PATCH v3 0/4] " Cedric Xing
2019-07-08 15:55 ` Sean Christopherson
2019-07-08 17:49 ` Xing, Cedric
2019-07-08 18:49 ` Sean Christopherson
2019-07-08 22:26 ` Xing, Cedric
2019-07-07 23:41 ` [RFC PATCH v3 1/4] x86/sgx: Add " Cedric Xing
2019-07-07 23:41 ` [RFC PATCH v3 2/4] x86/64: Call LSM hooks from SGX subsystem/module Cedric Xing
2019-07-09 1:03 ` Sean Christopherson
2019-07-07 23:41 ` [RFC PATCH v3 3/4] X86/sgx: Introduce EMA as a new LSM module Cedric Xing
2019-07-08 16:26 ` Casey Schaufler
2019-07-08 17:16 ` Xing, Cedric [this message]
2019-07-08 23:53 ` Casey Schaufler
2019-07-09 22:13 ` Xing, Cedric
2019-07-10 0:10 ` Casey Schaufler
2019-07-10 0:55 ` Xing, Cedric
2019-07-10 21:14 ` Casey Schaufler
2019-07-11 13:51 ` Stephen Smalley
2019-07-11 15:12 ` Sean Christopherson
2019-07-11 16:11 ` Stephen Smalley
2019-07-11 16:25 ` Sean Christopherson
2019-07-11 16:32 ` Stephen Smalley
2019-07-11 23:41 ` Xing, Cedric
2019-07-07 23:41 ` [RFC PATCH v3 4/4] x86/sgx: Implement SGX specific hooks in SELinux Cedric Xing
2019-07-09 1:33 ` Sean Christopherson
2019-07-09 21:26 ` Xing, Cedric
2019-07-10 15:49 ` Sean Christopherson
2019-07-10 16:08 ` Jethro Beekman
2019-07-10 18:16 ` Xing, Cedric
2019-07-10 17:54 ` Xing, Cedric
2019-06-27 18:56 ` [RFC PATCH v2 1/3] x86/sgx: Add SGX specific LSM hooks Cedric Xing
2019-06-27 22:06 ` Casey Schaufler
2019-06-27 22:52 ` Xing, Cedric
2019-06-27 23:37 ` Casey Schaufler
2019-06-28 0:47 ` Xing, Cedric
2019-06-28 17:22 ` Casey Schaufler
2019-06-28 22:29 ` Xing, Cedric
2019-06-29 1:37 ` Stephen Smalley
2019-06-29 21:35 ` Casey Schaufler
2019-07-01 17:57 ` Xing, Cedric
2019-07-01 19:53 ` Casey Schaufler
2019-07-01 21:45 ` Xing, Cedric
2019-07-01 23:11 ` Casey Schaufler
2019-07-02 7:42 ` Xing, Cedric
2019-07-02 15:44 ` Casey Schaufler
2019-07-03 9:46 ` Dr. Greg
2019-07-03 15:32 ` Casey Schaufler
2019-07-07 13:30 ` Dr. Greg
2019-07-09 0:02 ` Casey Schaufler
2019-07-09 1:52 ` Sean Christopherson
2019-07-09 21:16 ` Xing, Cedric
2019-07-11 10:22 ` Dr. Greg
2019-07-15 22:23 ` Andy Lutomirski
2019-06-28 16:37 ` Stephen Smalley
2019-06-28 21:53 ` Xing, Cedric
2019-06-29 1:22 ` Stephen Smalley
2019-07-01 18:02 ` Xing, Cedric
2019-06-29 23:46 ` Andy Lutomirski
2019-07-01 17:11 ` Xing, Cedric
2019-07-01 17:58 ` Andy Lutomirski
2019-07-01 18:31 ` Xing, Cedric
2019-07-01 19:36 ` Andy Lutomirski
2019-07-01 19:56 ` Xing, Cedric
2019-07-02 2:29 ` Andy Lutomirski
2019-07-02 6:35 ` Xing, Cedric
2019-06-27 18:56 ` [RFC PATCH v2 2/3] x86/sgx: Call LSM hooks from SGX subsystem/module Cedric Xing
2019-06-27 18:56 ` [RFC PATCH v2 3/3] x86/sgx: Implement SGX specific hooks in SELinux Cedric Xing
2019-07-05 16:05 ` [RFC PATCH v4 00/12] security: x86/sgx: SGX vs. LSM Jarkko Sakkinen
2019-07-08 17:29 ` Sean Christopherson
2019-07-08 17:33 ` Xing, Cedric
2019-07-09 16:22 ` Jarkko Sakkinen
2019-07-09 17:09 ` Sean Christopherson
2019-07-09 20:41 ` Xing, Cedric
2019-07-09 22:25 ` Sean Christopherson
2019-07-09 23:11 ` Xing, Cedric
2019-07-10 16:57 ` Sean Christopherson
2019-07-10 20:19 ` Jarkko Sakkinen
2019-07-10 20:31 ` Sean Christopherson
2019-07-11 9:06 ` Jarkko Sakkinen
2019-07-10 22:00 ` Jarkko Sakkinen
2019-07-10 22:16 ` Jarkko Sakkinen
2019-07-10 23:16 ` Xing, Cedric
2019-07-11 9:26 ` Jarkko Sakkinen
2019-07-11 14:32 ` Stephen Smalley
2019-07-11 17:51 ` Jarkko Sakkinen
2019-07-12 0:08 ` Xing, Cedric
2019-07-10 1:28 ` Dr. Greg
2019-07-10 2:04 ` Xing, Cedric
2019-07-10 3:21 ` Jethro Beekman
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