Problem mounting pseudo filesystems with SMACK and IMA enabled.

Problem mounting pseudo filesystems with SMACK and IMA enabled.

[Martin Townsend]

[Resending to new integrity mailing list]

Hi,

I have a system with a pre-signed UBI root filesystem image with both
IMA/EVM signatures on all files.  The Root CA Cert is compiled into
the kernel and the public keys is in the rootfs.  All SMACK labels
have also been applied although at this early stage there aren't many
(just a few application specific ones) so it's mainly the defaults.
This image is then flashed to the on board NAND.

The kernel bootargs for IMA are

"ima_audit=1 ima_template=ima-ng ima_hash=sha1 ima_tcb
ima_appraise_tcb rootflags=i_version"

and I'm enabling SMACK by using the kernel bootarg

"security=smack"

now if I boot without the "security=smack" it boots fine and I can
check the IMA/EVM signatures and can see that measurements are being
taken, but if I enable SMACK using the above kernel bootarg it fails
to boot and it looks like some problem early in systemd where it
mounts the required filesystems in mount-setup.c (log provided below).
Now if I flash an image that hasn't been signed and enable SMACK it
boots fine and I can use SMACK to enforce access control.  So there
seems to some interaction between the two when mounting the early
filesystems.

Before I delve into this I would appreciate any pointers to where to
start looking, any printk's to put in SMACK/IMA/mount code to help
diagnose this would be really appreciated.

The Kernel is 4.9 LTSI, systemd is v229

Apologies if I have the wrong mailing list for SMACK, I couldn't find
one on vger.kernel.org.


Boot log.
...
Security Framework initialized
Smack:  Initializing.
Smack:  IPv6 port labeling enabled.
Mount-cache hash table entries: 1024 (order: 0, 4096 bytes)
Mountpoint-cache hash table entries: 1024 (order: 0, 4096 bytes)
CPU: Testing write buffer coherency: ok
Setting up static identity map for 0x80100000 - 0x80100058
devtmpfs: initialized
evm: security.SMACK64
evm: security.SMACK64EXEC
evm: security.SMACK64TRANSMUTE
evm: security.SMACK64MMAP
evm: security.ima
evm: security.capability
...
Loading compiled-in X.509 certificates
Loaded X.509 cert 'IMA-EVM Root CA: cc972d25acf7c1efaa5329a48104efa303f0833a'
...
UBIFS (ubi0:0): FS size: 201764864 bytes (192 MiB, 1589 LEBs), journal
size 9023488 bytes (8 MiB, 72 LEBs)
UBIFS (ubi0:0): reserved for root: 0 bytes (0 KiB)
UBIFS (ubi0:0): media format: w4/r0 (latest is w4/r0), UUID
F6EA70A5-1931-4049-89CB-93B82F37F6A4, small LPT model
VFS: Mounted root (ubifs filesystem) readonly on device 0:16.
devtmpfs: mounted
integrity: Loaded X.509 cert 'IMA Certificate Authority:
e2c191a6e31fd02d6beba0c7c7847720a35fd9c6': /etc/keys/ima-x509.der
Freeing unused kernel memory: 1024K
systemd[1]: Successfully loaded Smack policies.
systemd[1]: Successfully loaded Smack/CIPSO policies.
systemd[1]: System time before build time, advancing clock.
systemd[1]: Failed to mount tmpfs at /dev/shm: No such file or directory
systemd[1]: Failed to mount tmpfs at /dev/shm: No such file or directory
systemd[1]: Failed to mount cgroup at /sys/fs/cgroup/systemd: No such
file or directory
[!!!!!!] Failed to mount API filesystems, freezing.
systemd[1]: Freezing execution.

Many Thanks,
Martin.

Re: Problem mounting pseudo filesystems with SMACK and IMA enabled.

[Mimi Zohar]

On Fri, 2018-03-16 at 09:32 +0000, Martin Townsend wrote:
> [Resending to new integrity mailing list]
> 
> Hi,
> 
> I have a system with a pre-signed UBI root filesystem image with both
> IMA/EVM signatures on all files.  The Root CA Cert is compiled into
> the kernel and the public keys is in the rootfs.  All SMACK labels
> have also been applied although at this early stage there aren't many
> (just a few application specific ones) so it's mainly the defaults.
> This image is then flashed to the on board NAND.
> 
> The kernel bootargs for IMA are
> 
> "ima_audit=1 ima_template=ima-ng ima_hash=sha1 ima_tcb
> ima_appraise_tcb rootflags=i_version"
> 
> and I'm enabling SMACK by using the kernel bootarg
> 
> "security=smack"
> 
> now if I boot without the "security=smack" it boots fine and I can
> check the IMA/EVM signatures and can see that measurements are being
> taken, but if I enable SMACK using the above kernel bootarg it fails
> to boot and it looks like some problem early in systemd where it
> mounts the required filesystems in mount-setup.c (log provided below).
> Now if I flash an image that hasn't been signed and enable SMACK it
> boots fine and I can use SMACK to enforce access control.  So there
> seems to some interaction between the two when mounting the early
> filesystems.
> 
> Before I delve into this I would appreciate any pointers to where to
> start looking, any printk's to put in SMACK/IMA/mount code to help
> diagnose this would be really appreciated.
> 
> The Kernel is 4.9 LTSI, systemd is v229
> 
> Apologies if I have the wrong mailing list for SMACK, I couldn't find
> one on vger.kernel.org.
> 
> 
> Boot log.
> ...
> Security Framework initialized
> Smack:  Initializing.
> Smack:  IPv6 port labeling enabled.
> Mount-cache hash table entries: 1024 (order: 0, 4096 bytes)
> Mountpoint-cache hash table entries: 1024 (order: 0, 4096 bytes)
> CPU: Testing write buffer coherency: ok
> Setting up static identity map for 0x80100000 - 0x80100058
> devtmpfs: initialized
> evm: security.SMACK64
> evm: security.SMACK64EXEC
> evm: security.SMACK64TRANSMUTE
> evm: security.SMACK64MMAP
> evm: security.ima
> evm: security.capability
> ...
> Loading compiled-in X.509 certificates
> Loaded X.509 cert 'IMA-EVM Root CA: cc972d25acf7c1efaa5329a48104efa303f0833a'
> ...
> UBIFS (ubi0:0): FS size: 201764864 bytes (192 MiB, 1589 LEBs), journal
> size 9023488 bytes (8 MiB, 72 LEBs)
> UBIFS (ubi0:0): reserved for root: 0 bytes (0 KiB)
> UBIFS (ubi0:0): media format: w4/r0 (latest is w4/r0), UUID
> F6EA70A5-1931-4049-89CB-93B82F37F6A4, small LPT model
> VFS: Mounted root (ubifs filesystem) readonly on device 0:16.
> devtmpfs: mounted
> integrity: Loaded X.509 cert 'IMA Certificate Authority:
> e2c191a6e31fd02d6beba0c7c7847720a35fd9c6': /etc/keys/ima-x509.der
> Freeing unused kernel memory: 1024K
> systemd[1]: Successfully loaded Smack policies.
> systemd[1]: Successfully loaded Smack/CIPSO policies.
> systemd[1]: System time before build time, advancing clock.
> systemd[1]: Failed to mount tmpfs at /dev/shm: No such file or directory
> systemd[1]: Failed to mount tmpfs at /dev/shm: No such file or directory
> systemd[1]: Failed to mount cgroup at /sys/fs/cgroup/systemd: No such
> file or directory
> [!!!!!!] Failed to mount API filesystems, freezing.
> systemd[1]: Freezing execution.

[Cc'ing Sascha]

Are there any additional messages in /var/log/audit/audit.log?

Mimi

Re: Problem mounting pseudo filesystems with SMACK and IMA enabled.

[Martin Townsend]

Hi Mimi,

On Fri, Mar 16, 2018 at 1:25 PM, Mimi Zohar <zohar@linux.vnet.ibm.com> wrote:
> On Fri, 2018-03-16 at 09:32 +0000, Martin Townsend wrote:
>> [Resending to new integrity mailing list]
>>
>> Hi,
>>
>> I have a system with a pre-signed UBI root filesystem image with both
>> IMA/EVM signatures on all files.  The Root CA Cert is compiled into
>> the kernel and the public keys is in the rootfs.  All SMACK labels
>> have also been applied although at this early stage there aren't many
>> (just a few application specific ones) so it's mainly the defaults.
>> This image is then flashed to the on board NAND.
>>
>> The kernel bootargs for IMA are
>>
>> "ima_audit=1 ima_template=ima-ng ima_hash=sha1 ima_tcb
>> ima_appraise_tcb rootflags=i_version"
>>
>> and I'm enabling SMACK by using the kernel bootarg
>>
>> "security=smack"
>>
>> now if I boot without the "security=smack" it boots fine and I can
>> check the IMA/EVM signatures and can see that measurements are being
>> taken, but if I enable SMACK using the above kernel bootarg it fails
>> to boot and it looks like some problem early in systemd where it
>> mounts the required filesystems in mount-setup.c (log provided below).
>> Now if I flash an image that hasn't been signed and enable SMACK it
>> boots fine and I can use SMACK to enforce access control.  So there
>> seems to some interaction between the two when mounting the early
>> filesystems.
>>
>> Before I delve into this I would appreciate any pointers to where to
>> start looking, any printk's to put in SMACK/IMA/mount code to help
>> diagnose this would be really appreciated.
>>
>> The Kernel is 4.9 LTSI, systemd is v229
>>
>> Apologies if I have the wrong mailing list for SMACK, I couldn't find
>> one on vger.kernel.org.
>>
>>
>> Boot log.
>> ...
>> Security Framework initialized
>> Smack:  Initializing.
>> Smack:  IPv6 port labeling enabled.
>> Mount-cache hash table entries: 1024 (order: 0, 4096 bytes)
>> Mountpoint-cache hash table entries: 1024 (order: 0, 4096 bytes)
>> CPU: Testing write buffer coherency: ok
>> Setting up static identity map for 0x80100000 - 0x80100058
>> devtmpfs: initialized
>> evm: security.SMACK64
>> evm: security.SMACK64EXEC
>> evm: security.SMACK64TRANSMUTE
>> evm: security.SMACK64MMAP
>> evm: security.ima
>> evm: security.capability
>> ...
>> Loading compiled-in X.509 certificates
>> Loaded X.509 cert 'IMA-EVM Root CA: cc972d25acf7c1efaa5329a48104efa303f0833a'
>> ...
>> UBIFS (ubi0:0): FS size: 201764864 bytes (192 MiB, 1589 LEBs), journal
>> size 9023488 bytes (8 MiB, 72 LEBs)
>> UBIFS (ubi0:0): reserved for root: 0 bytes (0 KiB)
>> UBIFS (ubi0:0): media format: w4/r0 (latest is w4/r0), UUID
>> F6EA70A5-1931-4049-89CB-93B82F37F6A4, small LPT model
>> VFS: Mounted root (ubifs filesystem) readonly on device 0:16.
>> devtmpfs: mounted
>> integrity: Loaded X.509 cert 'IMA Certificate Authority:
>> e2c191a6e31fd02d6beba0c7c7847720a35fd9c6': /etc/keys/ima-x509.der
>> Freeing unused kernel memory: 1024K
>> systemd[1]: Successfully loaded Smack policies.
>> systemd[1]: Successfully loaded Smack/CIPSO policies.
>> systemd[1]: System time before build time, advancing clock.
>> systemd[1]: Failed to mount tmpfs at /dev/shm: No such file or directory
>> systemd[1]: Failed to mount tmpfs at /dev/shm: No such file or directory
>> systemd[1]: Failed to mount cgroup at /sys/fs/cgroup/systemd: No such
>> file or directory
>> [!!!!!!] Failed to mount API filesystems, freezing.
>> systemd[1]: Freezing execution.
>
> [Cc'ing Sascha]
>
> Are there any additional messages in /var/log/audit/audit.log?
>
> Mimi
>

Sadly I can't see this file, I don't even think the relevant
filesystems have been mounted as this point. I tried the emergency
shell but no joy. Is there a way of patching the kernel to show audit
messages to the console?  If you point me at the relevant code I'll
hack something in.  I'm currently putting printk's everywhere I can
think of to see what's going on.   If you can think of anywhere in the
IMA that would be good to see a debug print let me know, currently I
have something in process_measurements and a few other places in
ima_main.c.

Cheers,
Martin.

Re: Problem mounting pseudo filesystems with SMACK and IMA enabled.

[Mimi Zohar]

On Fri, 2018-03-16 at 14:34 +0000, Martin Townsend wrote:
> Hi Mimi,
> 
> On Fri, Mar 16, 2018 at 1:25 PM, Mimi Zohar <zohar@linux.vnet.ibm.com> wrote:
> > On Fri, 2018-03-16 at 09:32 +0000, Martin Townsend wrote:
> >> [Resending to new integrity mailing list]
> >>
> >> Hi,
> >>
> >> I have a system with a pre-signed UBI root filesystem image with both
> >> IMA/EVM signatures on all files.  The Root CA Cert is compiled into
> >> the kernel and the public keys is in the rootfs.  All SMACK labels
> >> have also been applied although at this early stage there aren't many
> >> (just a few application specific ones) so it's mainly the defaults.
> >> This image is then flashed to the on board NAND.
> >>
> >> The kernel bootargs for IMA are
> >>
> >> "ima_audit=1 ima_template=ima-ng ima_hash=sha1 ima_tcb
> >> ima_appraise_tcb rootflags=i_version"
> >>
> >> and I'm enabling SMACK by using the kernel bootarg
> >>
> >> "security=smack"
> >>
> >> now if I boot without the "security=smack" it boots fine and I can
> >> check the IMA/EVM signatures and can see that measurements are being
> >> taken, but if I enable SMACK using the above kernel bootarg it fails
> >> to boot and it looks like some problem early in systemd where it
> >> mounts the required filesystems in mount-setup.c (log provided below).
> >> Now if I flash an image that hasn't been signed and enable SMACK it
> >> boots fine and I can use SMACK to enforce access control.  So there
> >> seems to some interaction between the two when mounting the early
> >> filesystems.
> >>
> >> Before I delve into this I would appreciate any pointers to where to
> >> start looking, any printk's to put in SMACK/IMA/mount code to help
> >> diagnose this would be really appreciated.
> >>
> >> The Kernel is 4.9 LTSI, systemd is v229
> >>
> >> Apologies if I have the wrong mailing list for SMACK, I couldn't find
> >> one on vger.kernel.org.
> >>
> >>
> >> Boot log.
> >> ...
> >> Security Framework initialized
> >> Smack:  Initializing.
> >> Smack:  IPv6 port labeling enabled.
> >> Mount-cache hash table entries: 1024 (order: 0, 4096 bytes)
> >> Mountpoint-cache hash table entries: 1024 (order: 0, 4096 bytes)
> >> CPU: Testing write buffer coherency: ok
> >> Setting up static identity map for 0x80100000 - 0x80100058
> >> devtmpfs: initialized
> >> evm: security.SMACK64
> >> evm: security.SMACK64EXEC
> >> evm: security.SMACK64TRANSMUTE
> >> evm: security.SMACK64MMAP
> >> evm: security.ima
> >> evm: security.capability
> >> ...
> >> Loading compiled-in X.509 certificates
> >> Loaded X.509 cert 'IMA-EVM Root CA: cc972d25acf7c1efaa5329a48104efa303f0833a'
> >> ...
> >> UBIFS (ubi0:0): FS size: 201764864 bytes (192 MiB, 1589 LEBs), journal
> >> size 9023488 bytes (8 MiB, 72 LEBs)
> >> UBIFS (ubi0:0): reserved for root: 0 bytes (0 KiB)
> >> UBIFS (ubi0:0): media format: w4/r0 (latest is w4/r0), UUID
> >> F6EA70A5-1931-4049-89CB-93B82F37F6A4, small LPT model
> >> VFS: Mounted root (ubifs filesystem) readonly on device 0:16.
> >> devtmpfs: mounted
> >> integrity: Loaded X.509 cert 'IMA Certificate Authority:
> >> e2c191a6e31fd02d6beba0c7c7847720a35fd9c6': /etc/keys/ima-x509.der
> >> Freeing unused kernel memory: 1024K
> >> systemd[1]: Successfully loaded Smack policies.
> >> systemd[1]: Successfully loaded Smack/CIPSO policies.
> >> systemd[1]: System time before build time, advancing clock.
> >> systemd[1]: Failed to mount tmpfs at /dev/shm: No such file or directory
> >> systemd[1]: Failed to mount tmpfs at /dev/shm: No such file or directory
> >> systemd[1]: Failed to mount cgroup at /sys/fs/cgroup/systemd: No such
> >> file or directory
> >> [!!!!!!] Failed to mount API filesystems, freezing.
> >> systemd[1]: Freezing execution.
> >
> > [Cc'ing Sascha]
> >
> > Are there any additional messages in /var/log/audit/audit.log?
> >
> > Mimi
> >
> 
> Sadly I can't see this file, I don't even think the relevant
> filesystems have been mounted as this point. I tried the emergency
> shell but no joy. Is there a way of patching the kernel to show audit
> messages to the console?  If you point me at the relevant code I'll
> hack something in.  I'm currently putting printk's everywhere I can
> think of to see what's going on.   If you can think of anywhere in the
> IMA that would be good to see a debug print let me know, currently I
> have something in process_measurements and a few other places in
> ima_main.c.

I would think the audit messages would go to the console.  With
dracut, I use a couple of boot command line options for debugging (eg.
rd.debug rd.break=pre-mount, rd.shell).

Mimi

Re: Problem mounting pseudo filesystems with SMACK and IMA enabled.

[Casey Schaufler]

On 3/16/2018 7:49 AM, Mimi Zohar wrote:
> On Fri, 2018-03-16 at 14:34 +0000, Martin Townsend wrote:
>> Hi Mimi,
>>
>> On Fri, Mar 16, 2018 at 1:25 PM, Mimi Zohar <zohar@linux.vnet.ibm.com> wrote:
>>> On Fri, 2018-03-16 at 09:32 +0000, Martin Townsend wrote:
>>>> [Resending to new integrity mailing list]
>>>>
>>>> Hi,
>>>>
>>>> I have a system with a pre-signed UBI root filesystem image with both
>>>> IMA/EVM signatures on all files.  The Root CA Cert is compiled into
>>>> the kernel and the public keys is in the rootfs.  All SMACK labels
>>>> have also been applied although at this early stage there aren't many
>>>> (just a few application specific ones) so it's mainly the defaults.

If you can apply a label to all of the files on the filesystem
( find $FSROOT -exec chsmack -a "_" {} \; ) and then set the
specific file labels you want you will ensure that you won't
go through the label defaulting mechanism. I don't think that
is your problem, but it's worth a try.

>>>> This image is then flashed to the on board NAND.
>>>>
>>>> The kernel bootargs for IMA are
>>>>
>>>> "ima_audit=1 ima_template=ima-ng ima_hash=sha1 ima_tcb
>>>> ima_appraise_tcb rootflags=i_version"
>>>>
>>>> and I'm enabling SMACK by using the kernel bootarg
>>>>
>>>> "security=smack"
>>>>
>>>> now if I boot without the "security=smack" it boots fine and I can
>>>> check the IMA/EVM signatures and can see that measurements are being
>>>> taken, but if I enable SMACK using the above kernel bootarg it fails
>>>> to boot and it looks like some problem early in systemd where it
>>>> mounts the required filesystems in mount-setup.c (log provided below).
>>>> Now if I flash an image that hasn't been signed and enable SMACK it
>>>> boots fine and I can use SMACK to enforce access control.  So there
>>>> seems to some interaction between the two when mounting the early
>>>> filesystems.
>>>>
>>>> Before I delve into this I would appreciate any pointers to where to
>>>> start looking, any printk's to put in SMACK/IMA/mount code to help
>>>> diagnose this would be really appreciated.
>>>>
>>>> The Kernel is 4.9 LTSI, systemd is v229

Are you using a base distribution? Fedora, Ubuntu, Debian, Alpine?
That information may make the issue easier to reproduce.

>>>>
>>>> Apologies if I have the wrong mailing list for SMACK, I couldn't find
>>>> one on vger.kernel.org.

SMACK-discuss@lists.01.org is the most Smack directed list.
linux-security-module@vger.kernel.org is the "official" place.
casey@schaufler-ca.com is me directly.

>>>>
>>>>
>>>> Boot log.
>>>> ...
>>>> Security Framework initialized
>>>> Smack:  Initializing.
>>>> Smack:  IPv6 port labeling enabled.
>>>> Mount-cache hash table entries: 1024 (order: 0, 4096 bytes)
>>>> Mountpoint-cache hash table entries: 1024 (order: 0, 4096 bytes)
>>>> CPU: Testing write buffer coherency: ok
>>>> Setting up static identity map for 0x80100000 - 0x80100058
>>>> devtmpfs: initialized
>>>> evm: security.SMACK64
>>>> evm: security.SMACK64EXEC
>>>> evm: security.SMACK64TRANSMUTE
>>>> evm: security.SMACK64MMAP
>>>> evm: security.ima
>>>> evm: security.capability
>>>> ...
>>>> Loading compiled-in X.509 certificates
>>>> Loaded X.509 cert 'IMA-EVM Root CA: cc972d25acf7c1efaa5329a48104efa303f0833a'
>>>> ...
>>>> UBIFS (ubi0:0): FS size: 201764864 bytes (192 MiB, 1589 LEBs), journal
>>>> size 9023488 bytes (8 MiB, 72 LEBs)
>>>> UBIFS (ubi0:0): reserved for root: 0 bytes (0 KiB)
>>>> UBIFS (ubi0:0): media format: w4/r0 (latest is w4/r0), UUID
>>>> F6EA70A5-1931-4049-89CB-93B82F37F6A4, small LPT model
>>>> VFS: Mounted root (ubifs filesystem) readonly on device 0:16.
>>>> devtmpfs: mounted
>>>> integrity: Loaded X.509 cert 'IMA Certificate Authority:
>>>> e2c191a6e31fd02d6beba0c7c7847720a35fd9c6': /etc/keys/ima-x509.der
>>>> Freeing unused kernel memory: 1024K
>>>> systemd[1]: Successfully loaded Smack policies.

Is your list of Smack rules large? What is it based on?

>>>> systemd[1]: Successfully loaded Smack/CIPSO policies.
>>>> systemd[1]: System time before build time, advancing clock.
>>>> systemd[1]: Failed to mount tmpfs at /dev/shm: No such file or directory
>>>> systemd[1]: Failed to mount tmpfs at /dev/shm: No such file or directory
>>>> systemd[1]: Failed to mount cgroup at /sys/fs/cgroup/systemd: No such
>>>> file or directory

This is where the audit trail could be very helpful. It can tell us
what action failed.

>>>> [!!!!!!] Failed to mount API filesystems, freezing.
>>>> systemd[1]: Freezing execution.
>>> [Cc'ing Sascha]
>>>
>>> Are there any additional messages in /var/log/audit/audit.log?
>>>
>>> Mimi
>>>
>> Sadly I can't see this file, I don't even think the relevant
>> filesystems have been mounted as this point. I tried the emergency
>> shell but no joy. Is there a way of patching the kernel to show audit
>> messages to the console?  If you point me at the relevant code I'll
>> hack something in.  I'm currently putting printk's everywhere I can
>> think of to see what's going on.   If you can think of anywhere in the
>> IMA that would be good to see a debug print let me know, currently I
>> have something in process_measurements and a few other places in
>> ima_main.c.
> I would think the audit messages would go to the console.  With
> dracut, I use a couple of boot command line options for debugging (eg.
> rd.debug rd.break=pre-mount, rd.shell).
>
> Mimi
>
>

Re: Problem mounting pseudo filesystems with SMACK and IMA enabled.

[Martin Townsend]

Hi Casey,

On Fri, Mar 16, 2018 at 3:52 PM, Casey Schaufler <casey@schaufler-ca.com> wrote:
> On 3/16/2018 7:49 AM, Mimi Zohar wrote:
>> On Fri, 2018-03-16 at 14:34 +0000, Martin Townsend wrote:
>>> Hi Mimi,
>>>
>>> On Fri, Mar 16, 2018 at 1:25 PM, Mimi Zohar <zohar@linux.vnet.ibm.com> wrote:
>>>> On Fri, 2018-03-16 at 09:32 +0000, Martin Townsend wrote:
>>>>> [Resending to new integrity mailing list]
>>>>>
>>>>> Hi,
>>>>>
>>>>> I have a system with a pre-signed UBI root filesystem image with both
>>>>> IMA/EVM signatures on all files.  The Root CA Cert is compiled into
>>>>> the kernel and the public keys is in the rootfs.  All SMACK labels
>>>>> have also been applied although at this early stage there aren't many
>>>>> (just a few application specific ones) so it's mainly the defaults.
>
> If you can apply a label to all of the files on the filesystem
> ( find $FSROOT -exec chsmack -a "_" {} \; ) and then set the
> specific file labels you want you will ensure that you won't
> go through the label defaulting mechanism. I don't think that
> is your problem, but it's worth a try.
>
I tried this but no joy.

>>>>> This image is then flashed to the on board NAND.
>>>>>
>>>>> The kernel bootargs for IMA are
>>>>>
>>>>> "ima_audit=1 ima_template=ima-ng ima_hash=sha1 ima_tcb
>>>>> ima_appraise_tcb rootflags=i_version"
>>>>>
>>>>> and I'm enabling SMACK by using the kernel bootarg
>>>>>
>>>>> "security=smack"
>>>>>
>>>>> now if I boot without the "security=smack" it boots fine and I can
>>>>> check the IMA/EVM signatures and can see that measurements are being
>>>>> taken, but if I enable SMACK using the above kernel bootarg it fails
>>>>> to boot and it looks like some problem early in systemd where it
>>>>> mounts the required filesystems in mount-setup.c (log provided below).
>>>>> Now if I flash an image that hasn't been signed and enable SMACK it
>>>>> boots fine and I can use SMACK to enforce access control.  So there
>>>>> seems to some interaction between the two when mounting the early
>>>>> filesystems.
>>>>>
>>>>> Before I delve into this I would appreciate any pointers to where to
>>>>> start looking, any printk's to put in SMACK/IMA/mount code to help
>>>>> diagnose this would be really appreciated.
>>>>>
>>>>> The Kernel is 4.9 LTSI, systemd is v229
>
> Are you using a base distribution? Fedora, Ubuntu, Debian, Alpine?
> That information may make the issue easier to reproduce.

It's a linux-yocto distribution for an i.MX6UL board. I'm trying to
get QEMU working to make it easier to debug and reproduce but alas
this may prove harder to achieve than debugging this issue with
printk's

>
>>>>>
>>>>> Apologies if I have the wrong mailing list for SMACK, I couldn't find
>>>>> one on vger.kernel.org.
>
> SMACK-discuss@lists.01.org is the most Smack directed list.
> linux-security-module@vger.kernel.org is the "official" place.
> casey@schaufler-ca.com is me directly.

Thank you I will use these in future.
>
>>>>>
>>>>>
>>>>> Boot log.
>>>>> ...
>>>>> Security Framework initialized
>>>>> Smack:  Initializing.
>>>>> Smack:  IPv6 port labeling enabled.
>>>>> Mount-cache hash table entries: 1024 (order: 0, 4096 bytes)
>>>>> Mountpoint-cache hash table entries: 1024 (order: 0, 4096 bytes)
>>>>> CPU: Testing write buffer coherency: ok
>>>>> Setting up static identity map for 0x80100000 - 0x80100058
>>>>> devtmpfs: initialized
>>>>> evm: security.SMACK64
>>>>> evm: security.SMACK64EXEC
>>>>> evm: security.SMACK64TRANSMUTE
>>>>> evm: security.SMACK64MMAP
>>>>> evm: security.ima
>>>>> evm: security.capability
>>>>> ...
>>>>> Loading compiled-in X.509 certificates
>>>>> Loaded X.509 cert 'IMA-EVM Root CA: cc972d25acf7c1efaa5329a48104efa303f0833a'
>>>>> ...
>>>>> UBIFS (ubi0:0): FS size: 201764864 bytes (192 MiB, 1589 LEBs), journal
>>>>> size 9023488 bytes (8 MiB, 72 LEBs)
>>>>> UBIFS (ubi0:0): reserved for root: 0 bytes (0 KiB)
>>>>> UBIFS (ubi0:0): media format: w4/r0 (latest is w4/r0), UUID
>>>>> F6EA70A5-1931-4049-89CB-93B82F37F6A4, small LPT model
>>>>> VFS: Mounted root (ubifs filesystem) readonly on device 0:16.
>>>>> devtmpfs: mounted
>>>>> integrity: Loaded X.509 cert 'IMA Certificate Authority:
>>>>> e2c191a6e31fd02d6beba0c7c7847720a35fd9c6': /etc/keys/ima-x509.der
>>>>> Freeing unused kernel memory: 1024K
>>>>> systemd[1]: Successfully loaded Smack policies.
>
> Is your list of Smack rules large? What is it based on?

At the moment there are 2 rules :)  It's not based on anything, the
next step is to start creating rules for the system but I don't
envisage that there will be many.

>
>>>>> systemd[1]: Successfully loaded Smack/CIPSO policies.
>>>>> systemd[1]: System time before build time, advancing clock.
>>>>> systemd[1]: Failed to mount tmpfs at /dev/shm: No such file or directory
>>>>> systemd[1]: Failed to mount tmpfs at /dev/shm: No such file or directory
>>>>> systemd[1]: Failed to mount cgroup at /sys/fs/cgroup/systemd: No such
>>>>> file or directory
>
> This is where the audit trail could be very helpful. It can tell us
> what action failed.

I thought I found the problem.  systemd was changing the SMACK label
on /dev to '*' and I had put IMA/EVM signature on /dev in the rootfs
so I was thinking the new SMACK label would break IMA/EVM for the dev
folder and as the first message were about /dev/shm not being found I
thought this was it.  But after removing the IMA/EVM signing of
directories, labelling /dev with '*' during the image signing and even
replacing all calls to lsetxattr in systemd with a log message the
problem still exists.

I put a printk at the end of common_lsm_audit and it never appeared so
I'm assuming there are no audit messages.  I put a prink on
process_measurements in IMA and it always returned 0 except for one
place where systemd was trying to load rules into load2

process_measurement: process_measurement: [smackfs magic:43415d53] /load2
process_measurements: ret -EACCESS rc:4

Not sure this is the problem though as there are 2 rules which are
application specific.  I load them later anyway with a systemd
service.  Put a printk on various SMACK functions including
smack_sb_kern_mount and they all return 0.

It looks like this is something particular to my system so I don't
want to take anymore of your time unless I find something that tells
me otherwise.  I'm going to start by investigating what's special
about mounting /dev/shm and /sys/fs/cgroup/systemd as these are the
two that are failing, it seems to mounting other things by looking at
the systemd mount table.

If anyone can suggest a good place to start looking that would be
appreciated otherwise I'll start with mounting code and shm code.

>
>>>>> [!!!!!!] Failed to mount API filesystems, freezing.
>>>>> systemd[1]: Freezing execution.
>>>> [Cc'ing Sascha]
>>>>
>>>> Are there any additional messages in /var/log/audit/audit.log?
>>>>
>>>> Mimi
>>>>
>>> Sadly I can't see this file, I don't even think the relevant
>>> filesystems have been mounted as this point. I tried the emergency
>>> shell but no joy. Is there a way of patching the kernel to show audit
>>> messages to the console?  If you point me at the relevant code I'll
>>> hack something in.  I'm currently putting printk's everywhere I can
>>> think of to see what's going on.   If you can think of anywhere in the
>>> IMA that would be good to see a debug print let me know, currently I
>>> have something in process_measurements and a few other places in
>>> ima_main.c.
>> I would think the audit messages would go to the console.  With
>> dracut, I use a couple of boot command line options for debugging (eg.
>> rd.debug rd.break=pre-mount, rd.shell).
>>
>> Mimi
>>
>>
>

Re: Problem mounting pseudo filesystems with SMACK and IMA enabled.

[Martin Townsend]

On Sat, Mar 17, 2018 at 9:20 AM, Martin Townsend
<mtownsend1973@gmail.com> wrote:
> Hi Casey,
>
> On Fri, Mar 16, 2018 at 3:52 PM, Casey Schaufler <casey@schaufler-ca.com> wrote:
>> On 3/16/2018 7:49 AM, Mimi Zohar wrote:
>>> On Fri, 2018-03-16 at 14:34 +0000, Martin Townsend wrote:
>>>> Hi Mimi,
>>>>
>>>> On Fri, Mar 16, 2018 at 1:25 PM, Mimi Zohar <zohar@linux.vnet.ibm.com> wrote:
>>>>> On Fri, 2018-03-16 at 09:32 +0000, Martin Townsend wrote:
>>>>>> [Resending to new integrity mailing list]
>>>>>>
>>>>>> Hi,
>>>>>>
>>>>>> I have a system with a pre-signed UBI root filesystem image with both
>>>>>> IMA/EVM signatures on all files.  The Root CA Cert is compiled into
>>>>>> the kernel and the public keys is in the rootfs.  All SMACK labels
>>>>>> have also been applied although at this early stage there aren't many
>>>>>> (just a few application specific ones) so it's mainly the defaults.
>>
>> If you can apply a label to all of the files on the filesystem
>> ( find $FSROOT -exec chsmack -a "_" {} \; ) and then set the
>> specific file labels you want you will ensure that you won't
>> go through the label defaulting mechanism. I don't think that
>> is your problem, but it's worth a try.
>>
> I tried this but no joy.
>
>>>>>> This image is then flashed to the on board NAND.
>>>>>>
>>>>>> The kernel bootargs for IMA are
>>>>>>
>>>>>> "ima_audit=1 ima_template=ima-ng ima_hash=sha1 ima_tcb
>>>>>> ima_appraise_tcb rootflags=i_version"
>>>>>>
>>>>>> and I'm enabling SMACK by using the kernel bootarg
>>>>>>
>>>>>> "security=smack"
>>>>>>
>>>>>> now if I boot without the "security=smack" it boots fine and I can
>>>>>> check the IMA/EVM signatures and can see that measurements are being
>>>>>> taken, but if I enable SMACK using the above kernel bootarg it fails
>>>>>> to boot and it looks like some problem early in systemd where it
>>>>>> mounts the required filesystems in mount-setup.c (log provided below).
>>>>>> Now if I flash an image that hasn't been signed and enable SMACK it
>>>>>> boots fine and I can use SMACK to enforce access control.  So there
>>>>>> seems to some interaction between the two when mounting the early
>>>>>> filesystems.
>>>>>>
>>>>>> Before I delve into this I would appreciate any pointers to where to
>>>>>> start looking, any printk's to put in SMACK/IMA/mount code to help
>>>>>> diagnose this would be really appreciated.
>>>>>>
>>>>>> The Kernel is 4.9 LTSI, systemd is v229
>>
>> Are you using a base distribution? Fedora, Ubuntu, Debian, Alpine?
>> That information may make the issue easier to reproduce.
>
> It's a linux-yocto distribution for an i.MX6UL board. I'm trying to
> get QEMU working to make it easier to debug and reproduce but alas
> this may prove harder to achieve than debugging this issue with
> printk's
>
>>
>>>>>>
>>>>>> Apologies if I have the wrong mailing list for SMACK, I couldn't find
>>>>>> one on vger.kernel.org.
>>
>> SMACK-discuss@lists.01.org is the most Smack directed list.
>> linux-security-module@vger.kernel.org is the "official" place.
>> casey@schaufler-ca.com is me directly.
>
> Thank you I will use these in future.
>>
>>>>>>
>>>>>>
>>>>>> Boot log.
>>>>>> ...
>>>>>> Security Framework initialized
>>>>>> Smack:  Initializing.
>>>>>> Smack:  IPv6 port labeling enabled.
>>>>>> Mount-cache hash table entries: 1024 (order: 0, 4096 bytes)
>>>>>> Mountpoint-cache hash table entries: 1024 (order: 0, 4096 bytes)
>>>>>> CPU: Testing write buffer coherency: ok
>>>>>> Setting up static identity map for 0x80100000 - 0x80100058
>>>>>> devtmpfs: initialized
>>>>>> evm: security.SMACK64
>>>>>> evm: security.SMACK64EXEC
>>>>>> evm: security.SMACK64TRANSMUTE
>>>>>> evm: security.SMACK64MMAP
>>>>>> evm: security.ima
>>>>>> evm: security.capability
>>>>>> ...
>>>>>> Loading compiled-in X.509 certificates
>>>>>> Loaded X.509 cert 'IMA-EVM Root CA: cc972d25acf7c1efaa5329a48104efa303f0833a'
>>>>>> ...
>>>>>> UBIFS (ubi0:0): FS size: 201764864 bytes (192 MiB, 1589 LEBs), journal
>>>>>> size 9023488 bytes (8 MiB, 72 LEBs)
>>>>>> UBIFS (ubi0:0): reserved for root: 0 bytes (0 KiB)
>>>>>> UBIFS (ubi0:0): media format: w4/r0 (latest is w4/r0), UUID
>>>>>> F6EA70A5-1931-4049-89CB-93B82F37F6A4, small LPT model
>>>>>> VFS: Mounted root (ubifs filesystem) readonly on device 0:16.
>>>>>> devtmpfs: mounted
>>>>>> integrity: Loaded X.509 cert 'IMA Certificate Authority:
>>>>>> e2c191a6e31fd02d6beba0c7c7847720a35fd9c6': /etc/keys/ima-x509.der
>>>>>> Freeing unused kernel memory: 1024K
>>>>>> systemd[1]: Successfully loaded Smack policies.
>>
>> Is your list of Smack rules large? What is it based on?
>
> At the moment there are 2 rules :)  It's not based on anything, the
> next step is to start creating rules for the system but I don't
> envisage that there will be many.
>
>>
>>>>>> systemd[1]: Successfully loaded Smack/CIPSO policies.
>>>>>> systemd[1]: System time before build time, advancing clock.
>>>>>> systemd[1]: Failed to mount tmpfs at /dev/shm: No such file or directory
>>>>>> systemd[1]: Failed to mount tmpfs at /dev/shm: No such file or directory
>>>>>> systemd[1]: Failed to mount cgroup at /sys/fs/cgroup/systemd: No such
>>>>>> file or directory
>>
>> This is where the audit trail could be very helpful. It can tell us
>> what action failed.
>
> I thought I found the problem.  systemd was changing the SMACK label
> on /dev to '*' and I had put IMA/EVM signature on /dev in the rootfs
> so I was thinking the new SMACK label would break IMA/EVM for the dev
> folder and as the first message were about /dev/shm not being found I
> thought this was it.  But after removing the IMA/EVM signing of
> directories, labelling /dev with '*' during the image signing and even
> replacing all calls to lsetxattr in systemd with a log message the
> problem still exists.
>
> I put a printk at the end of common_lsm_audit and it never appeared so
> I'm assuming there are no audit messages.  I put a prink on
> process_measurements in IMA and it always returned 0 except for one
> place where systemd was trying to load rules into load2
>
> process_measurement: process_measurement: [smackfs magic:43415d53] /load2
> process_measurements: ret -EACCESS rc:4
>
> Not sure this is the problem though as there are 2 rules which are
> application specific.  I load them later anyway with a systemd
> service.  Put a printk on various SMACK functions including
> smack_sb_kern_mount and they all return 0.
>
> It looks like this is something particular to my system so I don't
> want to take anymore of your time unless I find something that tells
> me otherwise.  I'm going to start by investigating what's special
> about mounting /dev/shm and /sys/fs/cgroup/systemd as these are the
> two that are failing, it seems to mounting other things by looking at
> the systemd mount table.
>
> If anyone can suggest a good place to start looking that would be
> appreciated otherwise I'll start with mounting code and shm code.
>
>>
>>>>>> [!!!!!!] Failed to mount API filesystems, freezing.
>>>>>> systemd[1]: Freezing execution.
>>>>> [Cc'ing Sascha]
>>>>>
>>>>> Are there any additional messages in /var/log/audit/audit.log?
>>>>>
>>>>> Mimi
>>>>>
>>>> Sadly I can't see this file, I don't even think the relevant
>>>> filesystems have been mounted as this point. I tried the emergency
>>>> shell but no joy. Is there a way of patching the kernel to show audit
>>>> messages to the console?  If you point me at the relevant code I'll
>>>> hack something in.  I'm currently putting printk's everywhere I can
>>>> think of to see what's going on.   If you can think of anywhere in the
>>>> IMA that would be good to see a debug print let me know, currently I
>>>> have something in process_measurements and a few other places in
>>>> ima_main.c.
>>> I would think the audit messages would go to the console.  With
>>> dracut, I use a couple of boot command line options for debugging (eg.
>>> rd.debug rd.break=pre-mount, rd.shell).
>>>
>>> Mimi
>>>
>>>
>>

The problem was because systemd couldn't create directories for the
mounts /dev/shm and /sys/fs/cgroup/systemd, it was returning -ENOKEY.
After investigating it looks like I need to set a key for HMAC to stop
the mkdir failing which I didn't appreciate I needed with a pre-signed
image.

I have a question on this, looking at the IMA code it will try and
replace my signatures with the HMAC unless the immutable attribute is
set, is this correct?  In the evmctl utility there's mention of an evm
immutable flag but I see nothing in the kernel code that supports
this. Is this a feature that never made it into the kernel? or is it
there but I've missed it?

Second question, I have no TPM module so do I need to add a key for
HMAC or is there another way? It's not a problem if I have to add a
key I just want to make 100% sure I have to before patching systemd or
creating my own init process that adds the key before handing over to
systemd.

Many Thanks, Martin.

Re: Problem mounting pseudo filesystems with SMACK and IMA enabled.

[Mimi Zohar]

On Mon, 2018-03-19 at 14:37 +0000, Martin Townsend wrote:
[...]
> The problem was because systemd couldn't create directories for the
> mounts /dev/shm and /sys/fs/cgroup/systemd, it was returning -ENOKEY.

There's a disconnect between what ima-evm-utils supports and the
kernel.  This sounds like the kernel you're using has directory
support, which has not been upstreamed.
  
> After investigating it looks like I need to set a key for HMAC to stop
> the mkdir failing which I didn't appreciate I needed with a pre-signed
> image.

> I have a question on this, looking at the IMA code it will try and
> replace my signatures with the HMAC unless the immutable attribute is
> set, is this correct?

EVM will replace the file signature with an HMAC, unless the
filesystem is mounted r/o, is immutable, or is signed with the new EVM
portable and immutable signature.

>  In the evmctl utility there's mention of an evm
> immutable flag but I see nothing in the kernel code that supports
> this. Is this a feature that never made it into the kernel? or is it
> there but I've missed it?

The portable and immutable EVM signature is being added only in this
release (linux-4.16).

> Second question, I have no TPM module so do I need to add a key for
> HMAC or is there another way? It's not a problem if I have to add a
> key I just want to make 100% sure I have to before patching systemd or
> creating my own init process that adds the key before handing over to
> systemd.

systemd already has support for loading an EVM key.

The EVM encrypted key could be based on either a TPM trusted key or a
user key, without the HW guarantees of the private key not being
exposed in the clear.  If you don't need an EVM key, then without a
TPM, you're probably better off backporting the new portable and
immutable EVM key.

Mimi

Re: Problem mounting pseudo filesystems with SMACK and IMA enabled.

[Martin Townsend]

On Mon, Mar 19, 2018 at 3:47 PM, Mimi Zohar <zohar@linux.vnet.ibm.com> wrote:
> On Mon, 2018-03-19 at 14:37 +0000, Martin Townsend wrote:
> [...]
>> The problem was because systemd couldn't create directories for the
>> mounts /dev/shm and /sys/fs/cgroup/systemd, it was returning -ENOKEY.
>
> There's a disconnect between what ima-evm-utils supports and the
> kernel.  This sounds like the kernel you're using has directory
> support, which has not been upstreamed.
>
>> After investigating it looks like I need to set a key for HMAC to stop
>> the mkdir failing which I didn't appreciate I needed with a pre-signed
>> image.
>
>> I have a question on this, looking at the IMA code it will try and
>> replace my signatures with the HMAC unless the immutable attribute is
>> set, is this correct?
>
> EVM will replace the file signature with an HMAC, unless the
> filesystem is mounted r/o, is immutable, or is signed with the new EVM
> portable and immutable signature.
>
>>  In the evmctl utility there's mention of an evm
>> immutable flag but I see nothing in the kernel code that supports
>> this. Is this a feature that never made it into the kernel? or is it
>> there but I've missed it?
>
> The portable and immutable EVM signature is being added only in this
> release (linux-4.16).
>
>> Second question, I have no TPM module so do I need to add a key for
>> HMAC or is there another way? It's not a problem if I have to add a
>> key I just want to make 100% sure I have to before patching systemd or
>> creating my own init process that adds the key before handing over to
>> systemd.
>
> systemd already has support for loading an EVM key.
>
> The EVM encrypted key could be based on either a TPM trusted key or a
> user key, without the HW guarantees of the private key not being
> exposed in the clear.  If you don't need an EVM key, then without a
> TPM, you're probably better off backporting the new portable and
> immutable EVM key.

I've taken a look at the kernel patch "EVM: Add support for portable
signature format" and this looks like the exact feature I've been
looking for :) and it applied fairly cleanly to 4.9 with just a couple
of easy manual edits.

I upgraded to the latest 1.1 ima-evm-utils on my host system but I
can't sign any files with the --portable flag.  (I've added the
function failing to the log_err function)

$ LD_LIBRARY_PATH=build/src/.libs sudo ./build/src/.libs/evmctl sign
--imasig -v -o --generation 0 --uuid  --key
/ws/rufilla/curtisswright/cwr-signing-authority/ca/ima/inter/private/ima-privkey.pem
/mnt/ubi/usr/bin/nsenter
hash: ccb3b93abd61cd1403ce00adbdbc1a75f2d5e9fb
evm/ima signature: 264 bytes
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
generation: 0
no xattr: security.selinux
no xattr: security.SMACK64
name: security.ima, size: 265
no xattr: security.capability
sign_evm: calc_evm_hash returned 20
hash: ad2747d58d06fe7ecf3fea272b68c058c4298941
evm/ima signature: 264 bytes
sign_evm: sign_hash returned 264
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
sign_evm: setxattr security.evm failed: /mnt/ubi/usr/bin/nsenter
: errno: Operation not permitted (1)
errno: Operation not permitted (1)


Yet without --portable it signs the file fine.

$ LD_LIBRARY_PATH=build/src/.libs sudo ./build/src/.libs/evmctl sign
--imasig -v --generation 0 --uuid  --key
/ws/rufilla/curtisswright/cwr-signing-authority/ca/ima/inter/private/ima-privkey.pem
/mnt/ubi/usr/bin/nsenter
hash: ccb3b93abd61cd1403ce00adbdbc1a75f2d5e9fb
evm/ima signature: 264 bytes
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
generation: 0
no xattr: security.selinux
no xattr: security.SMACK64
name: security.ima, size: 265
no xattr: security.capability
sign_evm: calc_evm_hash returned 20
hash: d1f22a34a86efc9f15345a39dae2e0c169373d75
evm/ima signature: 264 bytes
sign_evm: sign_hash returned 264
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


I've tried removing various parameters from evmctl but it still fails.
The only difference I can see in the code path is
if (evm_portable)
    sig[0] = EVM_XATTR_PORTABLE_DIGSIG;
else
    sig[0] = EVM_IMA_XATTR_DIGSIG;

before calling lsetxattr, so I followed lsetxattr in the kernel and I
think it's going to end up at security_inode_setxattr in security.c
which will then call evm_inode_setxattr which is going to fail on my
Host PC (Ubuntu 16.04 with a 4.13 kernel ) as it doesn't support this
new xattr data type:

if (xattr_data->type != EVM_IMA_XATTR_DIGSIG)
    return -EPERM;

Does this sound about right?

Many Thanks, Martin.
>
> Mimi
>

Re: Problem mounting pseudo filesystems with SMACK and IMA enabled.

[Mimi Zohar]

On Tue, 2018-03-20 at 10:23 +0000, Martin Townsend wrote:
> On Mon, Mar 19, 2018 at 3:47 PM, Mimi Zohar <zohar@linux.vnet.ibm.com> wrote:
> > On Mon, 2018-03-19 at 14:37 +0000, Martin Townsend wrote:
> > [...]
> >> The problem was because systemd couldn't create directories for the
> >> mounts /dev/shm and /sys/fs/cgroup/systemd, it was returning -ENOKEY.
> >
> > There's a disconnect between what ima-evm-utils supports and the
> > kernel.  This sounds like the kernel you're using has directory
> > support, which has not been upstreamed.
> >
> >> After investigating it looks like I need to set a key for HMAC to stop
> >> the mkdir failing which I didn't appreciate I needed with a pre-signed
> >> image.
> >
> >> I have a question on this, looking at the IMA code it will try and
> >> replace my signatures with the HMAC unless the immutable attribute is
> >> set, is this correct?
> >
> > EVM will replace the file signature with an HMAC, unless the
> > filesystem is mounted r/o, is immutable, or is signed with the new EVM
> > portable and immutable signature.
> >
> >>  In the evmctl utility there's mention of an evm
> >> immutable flag but I see nothing in the kernel code that supports
> >> this. Is this a feature that never made it into the kernel? or is it
> >> there but I've missed it?
> >
> > The portable and immutable EVM signature is being added only in this
> > release (linux-4.16).
> >
> >> Second question, I have no TPM module so do I need to add a key for
> >> HMAC or is there another way? It's not a problem if I have to add a
> >> key I just want to make 100% sure I have to before patching systemd or
> >> creating my own init process that adds the key before handing over to
> >> systemd.
> >
> > systemd already has support for loading an EVM key.
> >
> > The EVM encrypted key could be based on either a TPM trusted key or a
> > user key, without the HW guarantees of the private key not being
> > exposed in the clear.  If you don't need an EVM key, then without a
> > TPM, you're probably better off backporting the new portable and
> > immutable EVM key.
> 
> I've taken a look at the kernel patch "EVM: Add support for portable
> signature format" and this looks like the exact feature I've been
> looking for :) and it applied fairly cleanly to 4.9 with just a couple
> of easy manual edits.
> 
> I upgraded to the latest 1.1 ima-evm-utils on my host system but I
> can't sign any files with the --portable flag.  (I've added the
> function failing to the log_err function)
> 
> $ LD_LIBRARY_PATH=build/src/.libs sudo ./build/src/.libs/evmctl sign
> --imasig -v -o --generation 0 --uuid  --key

Can you try signing the file without "--generation 0 --uuid"?  Please
provide the output of "getfattr -m ^security -e hex --dump
<filename>".  The security.evm portable and immutable signature should
begin with 0x05.

Mimi


> /ws/rufilla/curtisswright/cwr-signing-authority/ca/ima/inter/private/ima-privkey.pem
> /mnt/ubi/usr/bin/nsenter
> hash: ccb3b93abd61cd1403ce00adbdbc1a75f2d5e9fb
> evm/ima signature: 264 bytes
> 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
> generation: 0
> no xattr: security.selinux
> no xattr: security.SMACK64
> name: security.ima, size: 265
> no xattr: security.capability
> sign_evm: calc_evm_hash returned 20
> hash: ad2747d58d06fe7ecf3fea272b68c058c4298941
> evm/ima signature: 264 bytes
> sign_evm: sign_hash returned 264
> 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
> sign_evm: setxattr security.evm failed: /mnt/ubi/usr/bin/nsenter
> : errno: Operation not permitted (1)
> errno: Operation not permitted (1)
> 
> 
> Yet without --portable it signs the file fine.
> 
> $ LD_LIBRARY_PATH=build/src/.libs sudo ./build/src/.libs/evmctl sign
> --imasig -v --generation 0 --uuid  --key
> /ws/rufilla/curtisswright/cwr-signing-authority/ca/ima/inter/private/ima-privkey.pem
> /mnt/ubi/usr/bin/nsenter
> hash: ccb3b93abd61cd1403ce00adbdbc1a75f2d5e9fb
> evm/ima signature: 264 bytes
> 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
> generation: 0
> no xattr: security.selinux
> no xattr: security.SMACK64
> name: security.ima, size: 265
> no xattr: security.capability
> sign_evm: calc_evm_hash returned 20
> hash: d1f22a34a86efc9f15345a39dae2e0c169373d75
> evm/ima signature: 264 bytes
> sign_evm: sign_hash returned 264
> 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
> 
> 
> I've tried removing various parameters from evmctl but it still fails.
> The only difference I can see in the code path is
> if (evm_portable)
>     sig[0] = EVM_XATTR_PORTABLE_DIGSIG;
> else
>     sig[0] = EVM_IMA_XATTR_DIGSIG;
> 
> before calling lsetxattr, so I followed lsetxattr in the kernel and I
> think it's going to end up at security_inode_setxattr in security.c
> which will then call evm_inode_setxattr which is going to fail on my
> Host PC (Ubuntu 16.04 with a 4.13 kernel ) as it doesn't support this
> new xattr data type:
> 
> if (xattr_data->type != EVM_IMA_XATTR_DIGSIG)
>     return -EPERM;
> 
> Does this sound about right?
> 
> Many Thanks, Martin.
> >
> > Mimi
> >
> 

Re: Problem mounting pseudo filesystems with SMACK and IMA enabled.

[Martin Townsend]

On Tue, Mar 20, 2018 at 1:32 PM, Mimi Zohar <zohar@linux.vnet.ibm.com> wrote:
> On Tue, 2018-03-20 at 10:23 +0000, Martin Townsend wrote:
>> On Mon, Mar 19, 2018 at 3:47 PM, Mimi Zohar <zohar@linux.vnet.ibm.com> wrote:
>> > On Mon, 2018-03-19 at 14:37 +0000, Martin Townsend wrote:
>> > [...]
>> >> The problem was because systemd couldn't create directories for the
>> >> mounts /dev/shm and /sys/fs/cgroup/systemd, it was returning -ENOKEY.
>> >
>> > There's a disconnect between what ima-evm-utils supports and the
>> > kernel.  This sounds like the kernel you're using has directory
>> > support, which has not been upstreamed.
>> >
>> >> After investigating it looks like I need to set a key for HMAC to stop
>> >> the mkdir failing which I didn't appreciate I needed with a pre-signed
>> >> image.
>> >
>> >> I have a question on this, looking at the IMA code it will try and
>> >> replace my signatures with the HMAC unless the immutable attribute is
>> >> set, is this correct?
>> >
>> > EVM will replace the file signature with an HMAC, unless the
>> > filesystem is mounted r/o, is immutable, or is signed with the new EVM
>> > portable and immutable signature.
>> >
>> >>  In the evmctl utility there's mention of an evm
>> >> immutable flag but I see nothing in the kernel code that supports
>> >> this. Is this a feature that never made it into the kernel? or is it
>> >> there but I've missed it?
>> >
>> > The portable and immutable EVM signature is being added only in this
>> > release (linux-4.16).
>> >
>> >> Second question, I have no TPM module so do I need to add a key for
>> >> HMAC or is there another way? It's not a problem if I have to add a
>> >> key I just want to make 100% sure I have to before patching systemd or
>> >> creating my own init process that adds the key before handing over to
>> >> systemd.
>> >
>> > systemd already has support for loading an EVM key.
>> >
>> > The EVM encrypted key could be based on either a TPM trusted key or a
>> > user key, without the HW guarantees of the private key not being
>> > exposed in the clear.  If you don't need an EVM key, then without a
>> > TPM, you're probably better off backporting the new portable and
>> > immutable EVM key.
>>
>> I've taken a look at the kernel patch "EVM: Add support for portable
>> signature format" and this looks like the exact feature I've been
>> looking for :) and it applied fairly cleanly to 4.9 with just a couple
>> of easy manual edits.
>>
>> I upgraded to the latest 1.1 ima-evm-utils on my host system but I
>> can't sign any files with the --portable flag.  (I've added the
>> function failing to the log_err function)
>>
>> $ LD_LIBRARY_PATH=build/src/.libs sudo ./build/src/.libs/evmctl sign
>> --imasig -v -o --generation 0 --uuid  --key
>
> Can you try signing the file without "--generation 0 --uuid"?  Please
> provide the output of "getfattr -m ^security -e hex --dump
> <filename>".  The security.evm portable and immutable signature should
> begin with 0x05.
>
I get the following
LD_LIBRARY_PATH=build/src/.libs sudo ./build/src/.libs/evmctl sign
--imasig -o --key
/ws/rufilla/curtisswright/cwr-signing-authority/ca/ima/inter/private/ima-privkey.pem
/mnt/ubi/usr/bin/nsenter
ioctl() failed
errno: Inappropriate ioctl for device (25)

You can see in the hexdump from my previous post below it tries to
send a signature with 05 at the start.

Reverting back to 1.0 ima-evm-utils and hacking the kernel to add the
EVM key it booted but I couldn't add SMACK rules in fact I couldn't do
anything with smackfs and after further debugging it was because
IMA/EVM was measuring and appraising everything in /sys/fs/smack
With the following patch I have finally got SMACK and IMA working together:

Re: Problem mounting pseudo filesystems with SMACK and IMA enabled.

[Mimi Zohar]

On Tue, 2018-03-20 at 15:01 +0000, Martin Townsend wrote:
> 
> Not sure why SMACK is not already there, do you want me to submit this
> patch formally or is there a good reason for the omission?

At some point, we should introduce a flag indicating a pseudo
fileesystem, but for now including SMACK in the list of pseudo
filesystems not measured sounds right. 

thanks,

Mimi

Re: Problem mounting pseudo filesystems with SMACK and IMA enabled.

[Casey Schaufler]

On 3/20/2018 9:11 AM, Mimi Zohar wrote:
> On Tue, 2018-03-20 at 15:01 +0000, Martin Townsend wrote:
>> Not sure why SMACK is not already there, do you want me to submit this
>> patch formally or is there a good reason for the omission?
> At some point, we should introduce a flag indicating a pseudo
> fileesystem, but for now including SMACK in the list of pseudo
> filesystems not measured sounds right.

I am also good with that.

>
> thanks,
>
> Mimi
>
>