[7/7] dm: add documentation for IMA measurement support

Commit Message

Tushar Sugandhi July 13, 2021, 12:49 a.m. UTC

To interpret various DM target measurement data in IMA logs,
a separate documentation page is needed under
Documentation/admin-guide/device-mapper.

Add documentation to help system administrators and attestation
client/server component owners to interpret the measurement
data generated by various DM targets, on various device/table state
changes.

Signed-off-by: Tushar Sugandhi <[e-mail]>
---
 .../admin-guide/device-mapper/dm-ima.rst      | 306 ++++++++++++++++++
 .../admin-guide/device-mapper/index.rst       |   1 +
 2 files changed, 307 insertions(+)
 create mode 100644 Documentation/admin-guide/device-mapper/dm-ima.rst

Comments

Mimi Zohar July 21, 2021, 2:33 a.m. UTC | #1

Hi Tushar, Mike,

On Mon, 2021-07-12 at 17:49 -0700, Tushar Sugandhi wrote:
> +Then IMA ASCII measurement log has the following format:
> +PCR TEMPLATE_DIGEST TEMPLATE ALG:EVENT_DIGEST EVENT_NAME EVENT_DATA
> +
> +PCR := Platform Configuration Register, in which the values are registered.
> +       This is applicable if TPM chip is in use.
> +TEMPLATE_DIGEST := Template digest of the IMA record.

^TEMPLATE_DATA_DIGEST

> +TEMPLATE := Template that registered the integrity value (e.g. ima-buf).

^TEMPLATE_NAME

The template data format consists of:
> +ALG:EVENT_DIGEST = Algorithm to compute event digest, followed by digest of event data
> +EVENT_NAME := Description of the event (e.g. 'table_load').
> +EVENT_DATA := The event data to be measured.

Missing from the document is a way of validating the template data. 
For example, in the original case of file measurements, the template
data contains the file hash, which can be recalculated or verified
against an allow list.

Other than re-calculating the template data digest based on the
template data, and verifying it against the template data digest in the
measurement list, would an attestation server be able to verify the
template data itself?

thanks,

Mimi

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Tushar Sugandhi July 24, 2021, 7:25 a.m. UTC | #2

Hi Mimi,

On 7/20/21 7:33 PM, Mimi Zohar wrote:
> Hi Tushar, Mike,
> 
> On Mon, 2021-07-12 at 17:49 -0700, Tushar Sugandhi wrote:
>> +Then IMA ASCII measurement log has the following format:
>> +PCR TEMPLATE_DIGEST TEMPLATE ALG:EVENT_DIGEST EVENT_NAME EVENT_DATA
>> +
>> +PCR := Platform Configuration Register, in which the values are registered.
>> +       This is applicable if TPM chip is in use.
>> +TEMPLATE_DIGEST := Template digest of the IMA record.
> 
> ^TEMPLATE_DATA_DIGEST
> 
Will do.

>> +TEMPLATE := Template that registered the integrity value (e.g. ima-buf).
> 
> ^TEMPLATE_NAME
>
Will do.

> The template data format consists of:
>> +ALG:EVENT_DIGEST = Algorithm to compute event digest, followed by digest of event data
>> +EVENT_NAME := Description of the event (e.g. 'table_load').
>> +EVENT_DATA := The event data to be measured.
> 
Thanks. I will add this to the dm-ima documentation.

> Missing from the document is a way of validating the template data.
> For example, in the original case of file measurements, the template
> data contains the file hash, which can be recalculated or verified
> against an allow list.
> 
> Other than re-calculating the template data digest based on the
> template data, and verifying it against the template data digest in the
> measurement list, would an attestation server be able to verify the
> template data itself?
>
Yes.
In the context of device-mapper, EVENT_DATA for 'table_load' would
contain the key-value pairs for various targets in the table
(crypt, verity, integrity etc.) which the attestation servers
should be able to verify against the allowed/expected
key-value pairs specified in the attestation policy.

To avoid bloating the IMA log with same data from table_load again,
we only measure hash of the loaded table in the EVENT_DATA -
when there is a state change for DM device.
e.g. when EVENT_NAME is 'device_resume', 'table_clear',
'device_remove' etc.

Since the table clear-text is already present in the EVENT_DATA
buffer for 'table_load', and is available to attestation servers,
verifying the corresponding hash values in the
EVENT_DATA in the subsequent DM events should be possible for
the attestation servers.

Please let us know if you need further info.

Thanks,
Tushar

> thanks,
> 
> Mimi
> 

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Mimi Zohar July 26, 2021, 4:33 p.m. UTC | #3

Hi Tushar,

On Sat, 2021-07-24 at 00:25 -0700, Tushar Sugandhi wrote:
> Hi Mimi,
> 
> 
> > Missing from the document is a way of validating the template data.
> > For example, in the original case of file measurements, the template
> > data contains the file hash, which can be recalculated or verified
> > against an allow list.
> > 
> > Other than re-calculating the template data digest based on the
> > template data, and verifying it against the template data digest in the
> > measurement list, would an attestation server be able to verify the
> > template data itself?
> >
> Yes.
> In the context of device-mapper, EVENT_DATA for 'table_load' would
> contain the key-value pairs for various targets in the table
> (crypt, verity, integrity etc.) which the attestation servers
> should be able to verify against the allowed/expected
> key-value pairs specified in the attestation policy.
> 
> To avoid bloating the IMA log with same data from table_load again,
> we only measure hash of the loaded table in the EVENT_DATA -
> when there is a state change for DM device.
> e.g. when EVENT_NAME is 'device_resume', 'table_clear',
> 'device_remove' etc.
> 
> Since the table clear-text is already present in the EVENT_DATA
> buffer for 'table_load', and is available to attestation servers,
> verifying the corresponding hash values in the
> EVENT_DATA in the subsequent DM events should be possible for
> the attestation servers.
> 
> Please let us know if you need further info.

For regular files with signatures, the file signature is verified
against the file hash, both contained within the template data.  For
the SELinux "critical-data", 
commit 2554a48f4437 ("selinux: measure state and policy capabilities")
contains that information.  Missing from this patch set is information
on how the attestation server could verify the DM critical data.

Does the DM record contain everything needed for the attestion server
to verify the template record?  Are things like the hash algorithm hard
coded?

thanks,

Mimi



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Tushar Sugandhi July 26, 2021, 6:28 p.m. UTC | #4

Hi Mimi,

On 7/26/21 9:33 AM, Mimi Zohar wrote:
> Hi Tushar,
> 
> On Sat, 2021-07-24 at 00:25 -0700, Tushar Sugandhi wrote:
>> Hi Mimi,
>>
>>
>>> Missing from the document is a way of validating the template data.
>>> For example, in the original case of file measurements, the template
>>> data contains the file hash, which can be recalculated or verified
>>> against an allow list.
>>>
>>> Other than re-calculating the template data digest based on the
>>> template data, and verifying it against the template data digest in the
>>> measurement list, would an attestation server be able to verify the
>>> template data itself?
>>>
>> Yes.
>> In the context of device-mapper, EVENT_DATA for 'table_load' would
>> contain the key-value pairs for various targets in the table
>> (crypt, verity, integrity etc.) which the attestation servers
>> should be able to verify against the allowed/expected
>> key-value pairs specified in the attestation policy.
>>
>> To avoid bloating the IMA log with same data from table_load again,
>> we only measure hash of the loaded table in the EVENT_DATA -
>> when there is a state change for DM device.
>> e.g. when EVENT_NAME is 'device_resume', 'table_clear',
>> 'device_remove' etc.
>>
>> Since the table clear-text is already present in the EVENT_DATA
>> buffer for 'table_load', and is available to attestation servers,
>> verifying the corresponding hash values in the
>> EVENT_DATA in the subsequent DM events should be possible for
>> the attestation servers.
>>
>> Please let us know if you need further info.
> 
> For regular files with signatures, the file signature is verified
> against the file hash, both contained within the template data.  For
> the SELinux "critical-data",
> commit 2554a48f4437 ("selinux: measure state and policy capabilities")
> contains that information.  Missing from this patch set is information
> on how the attestation server could verify the DM critical data.
> 
> Does the DM record contain everything needed for the attestion server
> to verify the template record?  Are things like the hash algorithm hard
> coded?
> 
Thanks for the feedback.
I think you have a point (on documenting hash algo and version in the
IMA record).

For the individual targets (crypt/linear etc.) the target version
is already recorded during table_load [1].
So for new attribute add/update/delete to those targets in future,
they should be accompanied by bumping the relevant target version.
So that the attestation servers would know what attributes to expect,
based on the target's version number.
So individual targets are already taken care of.

But for overall DM records I think some versioning would be useful
to the attestation servers, to determine what to expect for the
attributes that are at device level (i.e. not part of any individual
targets e.g. "minor_count", "num_targets" etc.).

Further, for the DM records that are not "table_load" - what hashing
algo is used to hash active/inactive table is the implementation detail
specific to DM, as Mike called out; and it is orthogonal to IMA's hash
algo.

But I think it would be useful to record the active/inactive table's
hash algo as part of the overall DM record template, so that attestation 
servers would know to how to interpret the relevant data.
(i.e. "active_table_hash", "inactive_table_hash" in [2]).

Both the changes are simple enough.

I will prototype and propose them as incremental patches along with
other changes (pointed to dm-5.15 branch as per Mike's suggestion.)

Thanks for your suggestions again.

Regards,
Tushar

[1]
+10 a8c5ff755561c7a28146389d1514c318592af49a ima-buf 
sha256:4d73481ecce5eadba8ab084640d85bb9ca899af4d0a122989252a76efadc5b72
+table_load
+name=linear1,uuid=,major=253,minor=0,minor_count=1,num_targets=1;
+target_index=0,target_begin=0,target_len=2,target_name=linear,target_version=1.4.0,device_name=7:0,start=512;


+table_load
+name=test-crypt,uuid=,major=253,minor=0,minor_count=1,num_targets=1;
+target_index=0,target_begin=0,target_len=1953125,target_name=crypt,target_version=1.23.0,


[2]
+device_remove
+device_active_metadata=name=linear1,uuid=,major=253,minor=0,minor_count=1,num_targets=4;
+device_inactive_metadata=name=linear1,uuid=,major=253,minor=0,minor_count=1,num_targets=2;
+active_table_hash=4d73481ecce5eadba8ab084640d85bb9ca899af4d0a122989252a76efadc5b72,
+inactive_table_hash=5596cc857b0e887fd0c5d58dc6382513284596b07f09fd37efae2da224bd521d,remove_all=n;
+current_device_capacity=8;
> thanks,
> 
> Mimi
> 
> 

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Patch

diff --git a/Documentation/admin-guide/device-mapper/dm-ima.rst b/Documentation/admin-guide/device-mapper/dm-ima.rst
new file mode 100644
index 000000000000..1be2da7c6b6b
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/dm-ima.rst
@@ -0,0 +1,306 @@ 
+======
+dm-ima
+======
+
+For a given system, various external services/infrastructure tools
+(including the attestation service) interact with it - both during the
+setup and during rest of the system run-time.  They share sensitive data
+and/or execute critical workload on that system.  The external services
+may want to verify the current run-time state of the relevant kernel
+subsystems before fully trusting the system with business-critical
+data/workload.
+
+Device mapper plays a critical role on a given system by providing
+various important functionalities to the block devices using various
+target types like crypt, verity, integrity etc.  Each of these target
+types’ functionalities can be configured with various attributes.
+The attributes chosen to configure these target types can significantly
+impact the security profile of the block device, and in-turn, of the
+system itself.  For instance, the type of encryption algorithm and the
+key size determines the strength of encryption for a given block device.
+
+Therefore, verifying the current state of various block devices as well
+as their various target attributes is crucial for external services before
+fully trusting the system with business-critical data/workload.
+
+IMA kernel subsystem provides the necessary functionality for
+device mapper to measure the state and configuration of
+various block devices -
+  - BY device mapper itself, from within the kernel,
+  - in a tamper resistant way,
+  - and re-measured - triggered on state/configuration change.
+
+Setting the IMA Policy:
+=======================
+For IMA to measure the data on a given system, the IMA policy on the
+system needs to be updated to have following line, and the system needs
+to be restarted for the measurements to take effect.
+
+/etc/ima/ima-policy
+ measure func=CRITICAL_DATA label=device-mapper template=ima-buf
+
+The measurements will be reflected in the IMA logs, which are located at:
+
+/sys/kernel/security/integrity/ima/ascii_runtime_measurements
+/sys/kernel/security/integrity/ima/binary_runtime_measurements
+
+Then IMA ASCII measurement log has the following format:
+PCR TEMPLATE_DIGEST TEMPLATE ALG:EVENT_DIGEST EVENT_NAME EVENT_DATA
+
+PCR := Platform Configuration Register, in which the values are registered.
+       This is applicable if TPM chip is in use.
+TEMPLATE_DIGEST := Template digest of the IMA record.
+TEMPLATE := Template that registered the integrity value (e.g. ima-buf).
+ALG:EVENT_DIGEST = Algorithm to compute event digest, followed by digest of event data
+EVENT_NAME := Description of the event (e.g. 'table_load').
+EVENT_DATA := The event data to be measured.
+
+The DM target data measured by IMA subsystem can alternatively
+be queried from userspace by setting DM_IMA_MEASUREMENT_FLAG with
+DM_TABLE_STATUS_CMD.
+
+Supported Device States:
+========================
+Following device state changes will trigger IMA measurements.
+01. Table load
+02. Device resume
+03. Device remove
+04. Table clear
+05. Device rename
+
+01. Table load:
+---------------
+When a new table is loaded in a device's inactive table slot,
+the device information and target specific details from the
+targets in the table are measured.
+
+For instance, if a linear device is created with the following table entries,
+# dmsetup create linear1
+0 2 linear /dev/loop0 512
+2 2 linear /dev/loop0 512
+4 2 linear /dev/loop0 512
+6 2 linear /dev/loop0 512
+
+Then IMA ASCII measurement log will have an entry with:
+EVENT_NAME := table_load
+EVENT_DATA := [device_data];[target_data_row_1];[target_data_row_2];...[target_data_row_n];
+
+E.g.
+(converted from ASCII to text for readability)
+10 a8c5ff755561c7a28146389d1514c318592af49a ima-buf sha256:4d73481ecce5eadba8ab084640d85bb9ca899af4d0a122989252a76efadc5b72
+table_load
+name=linear1,uuid=,major=253,minor=0,minor_count=1,num_targets=4;
+target_index=0,target_begin=0,target_len=2,target_type_name=linear,target_type_version=1.4.0,device_name=7:0,start=512;
+target_index=1,target_begin=2,target_len=2,target_type_name=linear,target_type_version=1.4.0,device_name=7:0,start=512;
+target_index=2,target_begin=4,target_len=2,target_type_name=linear,target_type_version=1.4.0,device_name=7:0,start=512;
+target_index=3,target_begin=6,target_len=2,target_type_name=linear,target_type_version=1.4.0,device_name=7:0,start=512;
+
+02. Device resume:
+------------------
+When a suspended device is resumed, the device information and a sha256 hash of the
+data from previous load of an active table are measured.
+
+For instance, if a linear device is resumed with the following command,
+#dmsetup resume linear1
+
+Then IMA ASCII measurement log will have an entry with:
+EVENT_NAME := device_resume
+EVENT_DATA := [device_data];active_table_hash=(sha256hash([device_data];[target_data_row_1];...[target_data_row_n]);
+              current_device_capacity=<N>;
+
+E.g.
+(converted from ASCII to text for readability)
+10 56c00cc062ffc24ccd9ac2d67d194af3282b934e ima-buf sha256:e7d12c03b958b4e0e53e7363a06376be88d98a1ac191fdbd3baf5e4b77f329b6
+device_resume
+name=linear1,uuid=,major=253,minor=0,minor_count=1,num_targets=4;
+active_table_hash=4d73481ecce5eadba8ab084640d85bb9ca899af4d0a122989252a76efadc5b72;current_device_capacity=8;
+
+03. Device remove:
+------------------
+When a device is removed, the device information and a sha256 hash of the
+data from an active and inactive table are measured.
+
+For instance, if a linear device is removed with the following command,
+# dmsetup remove linear1
+
+Then IMA ASCII measurement log will have an entry with:
+EVENT_NAME := device_remove
+EVENT_DATA := [device_active_metadata];[device_inactive_metadata];
+              [active_table_hash=(sha256hash([device_active_metadata];[active_table_row_1];...[active_table_row_n]),
+              [inactive_table_hash=(sha256hash([device_inactive_metadata];[inactive_table_row_1];...[inactive_table_row_n]),
+              remove_all=[y|n];current_device_capacity=<N>;
+
+E.g
+(converted from ASCII to text for readability)
[phone]b621b705061c4514d643894483e16d2619 ima-buf sha256:c3f26b02f09bf5b464925589454bdd4d354077ce430fd1e75c9e96ce29cd1cad
+device_remove
+device_active_metadata=name=linear1,uuid=,major=253,minor=0,minor_count=1,num_targets=4;
+device_inactive_metadata=name=linear1,uuid=,major=253,minor=0,minor_count=1,num_targets=2;
+active_table_hash=4d73481ecce5eadba8ab084640d85bb9ca899af4d0a122989252a76efadc5b72,
+inactive_table_hash=5596cc857b0e887fd0c5d58dc6382513284596b07f09fd37efae2da224bd521d,remove_all=n;
+current_device_capacity=8;
+
+
+04. Table clear:
+----------------
+When an inactive table is cleared from the device, the device information and a sha256 hash of the
+data from an inactive table are measured.
+
+For instance, if a linear device's inactive table is cleared with the following command,
+
+# dmsetup clear linear1
+
+Then IMA ASCII measurement log will have an entry with:
+EVENT_NAME := table_clear
+EVENT_DATA := [device_data];inactive_table_hash=(sha256hash([device_data];[inactive_table_row_1];...[inactive_table_row_n]);
+current_device_capacity=<N>;
+
+E.g.
+(converted from ASCII to text for readability)
+10 9c11e284d792875352d51c09f6643c96649484be ima-buf sha256:84b22b364ea4d8264fa33c38635c18ef448fa9077731fa7e5f969b1da2003ea4
+table_clear
+name=linear1,uuid=,major=253,minor=0,minor_count=1,num_targets=2;
+inactive_table_hash=5596cc857b0e887fd0c5d58dc6382513284596b07f09fd37efae2da224bd521d;current_device_capacity=0;
+
+
+05. Device rename:
+------------------
+When an device's NAME or UUID is changed, the device information and the new NAME and UUID
+are measured.
+
+For instance, if a linear device's name is changed with the following command,
+
+#dmsetup rename linear1 linear=2
+Then IMA ASCII measurement log will have an entry with:
+EVENT_NAME := device_rename
+EVENT_DATA := [current_device_data];new_name=<new_name_value>;new_uuid=<new_uuid_value>;current_device_capacity=<N>;
+
+E.g 1:
+#dmsetup rename linear1 --setuuid 1234-5678
+
+IMA Log entry:
+(converted from ASCII to text for readability)
+10 7380ef4d1349fe1ebd74affa54e9fcc960e3cbf5 ima-buf sha256:9759e36a17a967ea43c1bf3455279395a40bd0401105ec5ad8edb9a52054efc7
+device_rename
+name=linear1,uuid=,major=253,minor=0,minor_count=1,num_targets=1;new_name=linear1,new_uuid=1234-5678;current_device_capacity=2;
+
+E.g 2:
+# dmsetup rename linear1 linear=2
+10 092c8266fc36e44f74c59f123ecfe15310f249f4 ima-buf sha256:4cf8b85c81fa6fedaeb602b05019124dbbb0605dce58fcdeea56887a8a3874cd
+device_rename
+name=linear1,uuid=1234-5678,major=253,minor=0,minor_count=1,num_targets=1;new_name=linear\=2,new_uuid=1234-5678;current_device_capacity=2;
+
+
+Supported targets:
+==================
+Following targets are supported to measure their data using IMA.
+
+01. cache
+02. crypt
+03. integrity
+04. linear
+05. mirror
+06. multipath
+07. raid
+08. snapshot
+09. striped
+10. verity
+
+01. cache
+---------
+<<documenatation in progress>>
+
+02. crypt
+-----
+When a crypt target is loaded, then IMA ASCII measurement log will have an entry
+similar to the following, depicting what crypt attributes are measured in EVENT_DATA.
+
+(converted from ASCII to text for readability)
+10 fe3b80a35b155bd282df778e2625066c05fc068c ima-buf sha256:2d86ce9d6f16a4a97607318aa123ae816e0ceadefeea7903abf7f782f2cb78ad
+table_load
+name=test-crypt,uuid=,major=253,minor=0,minor_count=1,num_targets=1;
+target_index=0,target_begin=0,target_len=1953125,target_type_name=crypt,target_type_version=1.23.0,
+allow_discards=y,same_cpu=n,submit_from_crypt_cpus=n,no_read_workqueue=n,no_write_workqueue=n,
+iv_large_sectors=n,cipher_string=aes-xts-plain64,key_size=32,key_parts=1,key_extra_size=0,key_mac_size=0;
+
+03. integrity
+-------------
+<<documenatation in progress>>
+
+
+04. linear
+----------
+When a linear target is loaded, then IMA ASCII measurement log will have an entry
+similar to the following, depicting what linear attributes are measured in EVENT_DATA.
+
+(converted from ASCII to text for readability)
+10 a8c5ff755561c7a28146389d1514c318592af49a ima-buf sha256:4d73481ecce5eadba8ab084640d85bb9ca899af4d0a122989252a76efadc5b72
+table_load
+name=linear1,uuid=,major=253,minor=0,minor_count=1,num_targets=4;
+target_index=0,target_begin=0,target_len=2,target_type_name=linear,target_type_version=1.4.0,device_name=7:0,start=512;
+target_index=1,target_begin=2,target_len=2,target_type_name=linear,target_type_version=1.4.0,device_name=7:0,start=512;
+target_index=2,target_begin=4,target_len=2,target_type_name=linear,target_type_version=1.4.0,device_name=7:0,start=512;
+target_index=3,target_begin=6,target_len=2,target_type_name=linear,target_type_version=1.4.0,device_name=7:0,start=512;
+
+05. mirror
+----------
+When a mirror target is loaded, then IMA ASCII measurement log will have an entry
+similar to the following, depicting what mirror attributes are measured in EVENT_DATA.
+
+(converted from ASCII to text for readability)
+10 90ff9113a00c367df823595dc347425ce3bfc50a ima-buf sha256:8da0678ed3bf616533573d9e61e5342f2bd16cb0b3145a08262641a743806c2e
+table_load
+name=test-mirror,uuid=,major=253,minor=4,minor_count=1,num_targets=1;
+target_index=0,target_begin=0,target_len=1953125,target_type_name=mirror,target_type_version=1.14.0,
+mirrors=2,mirror_device_0=253:2,mirror_device_0_status=A,mirror_device_1=253:3,mirror_device_1_status=A,
+handle_errors=y,keep_log=n,log_type_status=;
+
+06. multipath
+-------------
+<<documenatation in progress>>
+
+07. raid
+--------
+When a raid target is loaded, then IMA ASCII measurement log will have an entry
+similar to the following, depicting what raid attributes are measured in EVENT_DATA.
+
+(converted from ASCII to text for readability)
+10 76cb30d0cd0fe099966f20f5c82e3a2ac29b21a0 ima-buf sha256:52250f20b27376fcfb348bdfa1e1cf5acfd6646e0f3ad1a72952cffd9f818753
+table_load
+name=test-raid1,uuid=,major=253,minor=2,minor_count=1,num_targets=1;
+target_index=0,target_begin=0,target_len=1953125,target_type_name=raid,target_type_version=1.15.1,
+raid_type=raid1,raid_disks=2,raid_state=idle,raid_device_0_status=A,raid_device_1_status=A;
+
+08. snapshot
+------------
+<<documenatation in progress>>
+
+09. striped
+----------
+When a linear target is loaded, then IMA ASCII measurement log will have an entry
+similar to the following, depicting what linear attributes are measured in EVENT_DATA.
+
+(converted from ASCII to text for readability)
+10 7bd94fa8f799169b9f12d97b9dbdce4dc5509233 ima-buf sha256:0d148eda69887f7833f1a6042767b54359cd23b64fa941b9e1856879eee1f778
+table_load
+name=test-raid0,uuid=,major=253,minor=8,minor_count=1,num_targets=1;
+target_index=0,target_begin=0,target_len=7812096,target_type_name=striped,target_type_version=1.6.0,stripes=4,chunk_size=128,
+stripe_0_device_name=253:1,stripe_0_physical_start=0,stripe_0_status=A,
+stripe_1_device_name=253:3,stripe_1_physical_start=0,stripe_1_status=A,
+stripe_2_device_name=253:5,stripe_2_physical_start=0,stripe_2_status=A,
+stripe_3_device_name=253:7,stripe_3_physical_start=0,stripe_3_status=A;
+
+10. verity
+----------
+When a verity target is loaded, then IMA ASCII measurement log will have an entry
+similar to the following, depicting what verity attributes are measured in EVENT_DATA.
+
+(converted from ASCII to text for readability)
+10 fced5f575b140fc0efac302c88a635174cd663da ima-buf sha256:021370c1cc93929460b06922c606334fb1d7ea5ecf04f2384f3157a446894283
+table_load
+name=test-verity,uuid=,major=253,minor=2,minor_count=1,num_targets=1;
+target_index=0,target_begin=0,target_len=1953120,target_type_name=verity,target_type_version=1.8.0,hash_failed=V,
+verity_version=1,data_device_name=253:1,hash_device_name=253:0,verity_algorithm=sha256,
+root_digest=29cb87e60ce7b12b443ba6008266f3e41e93e403d7f298f8e3f316b29ff89c5e,
+salt=e48da609055204e89ae53b655ca2216dd983cf3cb829f34f63a297d106d53e2d,
+ignore_zero_blocks=n,check_at_most_once=n;
diff --git a/Documentation/admin-guide/device-mapper/index.rst b/Documentation/admin-guide/device-mapper/index.rst
index 6cf8adc86fa8..cde52cc09645 100644
--- a/Documentation/admin-guide/device-mapper/index.rst
+++ b/Documentation/admin-guide/device-mapper/index.rst
@@ -13,6 +13,7 @@  Device Mapper
     dm-dust
     dm-ebs
     dm-flakey
+    dm-ima
     dm-init
     dm-integrity
     dm-io