[18.04 FEAT] zcrypt DD: introduce APQN tags to support deterministic driver binding
| Affects | Status | Importance | Assigned to | Milestone | |
|---|---|---|---|---|---|
| Ubuntu on IBM z Systems |
Fix Released
|
High
|
Canonical Kernel Team | ||
| linux (Ubuntu) |
Fix Released
|
High
|
Joseph Salisbury | ||
| Bionic |
Fix Released
|
High
|
Joseph Salisbury | ||
Bug Description
== SRU Justification ==
APQN tags in the zcrypt device driver are required to support deterministic driver binding
With the introduction of KVM hw crypto virtualization (on s390x) the driver bound to an AP queue device is no longer unique determined.
Therefore a deterministic hot plugging semantics of AP queues that may be bound to multiple drivers is needed.
With the three listed commits here it will be possible to configure an AP queue (APQN) as being bound to a particular driver even if the associate hw gets intermittently lost and reconnected.
== Fixes ==
ac2b96f351d7d222 ("s390/zcrypt: code beautify")
7e0bdbe5c21cb831 ("s390/zcrypt: AP bus support for alternate driver(s)")
3d8f60d38e249f98 ("s390/zcrypt: hex string mask improvements for apmask and aqmask")
== Patches ==
Git-commit: ac2b96f351d7d222
https:/
Author: Harald Freudenberger <email address hidden>
Date: Fri Aug 17 12:36:01 2018 +0200
s390/zcrypt: code beautify
Code beautify by following most of the checkpatch suggestions:
- SPDX license identifier line complains by checkpatch
- missing space or newline complains by checkpatch
- octal numbers for permssions complains by checkpatch
- renaming of static sysfs functions complains by checkpatch
- fix of block comment complains by checkpatch
- fix printf like calls where function name instead of %s __func__
was used
- __packed instead of __attribute_
- init to zero for static variables removed
- use of DEVICE_ATTR_RO and DEVICE_ATTR_RW macros
No functional code changes or API changes!
Signed-off-by: Harald Freudenberger <email address hidden>
Signed-off-by: Martin Schwidefsky <email address hidden>
===
Git-commit 7e0bdbe5c21cb831
https:/
Author: Harald Freudenberger <email address hidden>
Date: Fri Jul 20 08:36:53 2018 +0200
s390/zcrypt: AP bus support for alternate driver(s)
The current AP bus, AP devices and AP device drivers implementation
uses a clearly defined mapping for binding AP devices to AP device
drivers. So for example a CEX6C queue will always be bound to the
cex4queue device driver.
The Linux Device Driver model has no sensitivity for more than one
device driver eligible for one device type. If there exist more than
one drivers matching to the device type, simple all drivers are tried
consecutively. There is no way to determine and influence the probing
order of the drivers.
With KVM there is a need to provide additional device drivers matching
to the very same type of AP devices. With a simple implementation the
KVM drivers run in competition to the regular drivers. Whichever
'wins' a device depends on build order and implementation details
within the common Linux Device Driver Model and is not
deterministic. However, a userspace process could figure out which
device should be bound to which driver and sort out the correct
binding by manipulating attributes in the sysfs.
If for security reasons a AP device must not get bound to the 'wrong'
device driver the sorting out has to be done within the Linux kernel
by the AP bus code. This patch modifies the behavior of the AP bus
for probing drivers for devices in a way that two sets of drivers are
usable. Two new bitmasks 'apmask' and 'aqmask' are used to mark a
subset of the APQN range for 'usable by the ap bus and the default
drivers' or 'not usable by the default drivers and thus available for
alternate drivers like vfio-xxx'. So an APQN which is addressed by
this masking only the default drivers will be probed. In contrary an
APQN which is not addressed by the masks will never be probed and
bound to default drivers but onny to alternate drivers.
Eventually the two masks give a way to divide the range of APQNs into
two pools: one pool of APQNs used by the AP bus and the default
drivers and thus via zcrypt drivers available to the userspace of the
system. And another pool where no zcrypt drivers are bound to and
which can be used by alternate drivers (like vfio-xxx) for their
needs. This division is hot-plug save and makes sure a APQN assigned
to an alternate driver is at no time somehow exploitable by the wrong
party.
The two masks are located in sysfs at /sys/bus/ap/apmask and
/sys/bus/ap/aqmask. The mask syntax is exactly the same as the
already existing mask attributes in the /sys/bus/ap directory (for
example ap_usage_
By default all APQNs belong to the ap bus and the default drivers:
cat /sys/bus/ap/apmask
0xfffffffffff
cat /sys/bus/ap/aqmask
0xfffffffffff
The masks can be changed at boot time with the kernel command line
like this:
... ap.apmask=0xffff ap.aqmask=0x40
This would give these two pools:
default drivers pool: adapter 0 - 15, domain 1
alternate drivers pool: adapter 0 - 15, all but domain 1
adapter 16-255, all domains
The sysfs attributes for this two masks are writeable and an
administrator is able to reconfigure the assignements on the fly by
writing new mask values into. With changing the mask(s) a revision of
the existing queue to driver bindings is done. So all APQNs which are
bound to the 'wrong' driver are reprobed via kernel function
device_reprobe() and thus the new correct driver will be assigned with
respect of the changed apmask and aqmask bits.
The mask values are bitmaps in big endian order starting with bit 0.
So adapter number 0 is the leftmost bit, mask is 0x8000... The sysfs
attributes accept 2 different formats:
- Absolute hex string starting with 0x like "0x12345678" does set
the mask starting from left to right. If the given string is shorter
than the mask it is padded with 0s on the right. If the string is
longer than the mask an error comes back (EINVAL).
- '+' or '-' followed by a numerical value. Valid examples are "+1",
"-13", "+0x41", "-0xff" and even "+0" and "-0". Only the addressed
bit in the mask is switched on ('+') or off ('-').
This patch will also be the base for an upcoming extension to the
zcrypt drivers to be able to provide additional zcrypt device nodes
with filtering based on ap and aq masks.
Signed-off-by: Harald Freudenberger <email address hidden>
Signed-off-by: Martin Schwidefsky <email address hidden>
===
Git-commit 3d8f60d38e249f98
https:/
Author: Harald Freudenberger <email address hidden>
Date: Mon Aug 20 15:27:45 2018 +0200
s390/zcrypt: hex string mask improvements for apmask and aqmask
The sysfs attributes /sys/bus/ap/apmask and /sys/bus/ap/aqmask
and the kernel command line arguments ap.apm and ap.aqm get
an improvement of the value parsing with this patch:
The mask values are bitmaps in big endian order starting with bit 0.
So adapter number 0 is the leftmost bit, mask is 0x8000... The sysfs
attributes and the kernel command line accept 2 different formats:
- Absolute hex string starting with 0x like "0x12345678" does set
the mask starting from left to right. If the given string is shorter
than the mask it is padded with 0s on the right. If the string is
longer than the mask an error comes back (EINVAL).
- Relative format - a concatenation (done with ',') of the terms
+<bitnr>
valid number (hex, decimal or octal) in the range 0...255.
Here are some examples:
"+
"-
Signed-off-by: Harald Freudenberger <email address hidden>
Signed-off-by: Martin Schwidefsky <email address hidden>
== Regression Potential ==
Mid to low, because:
- There are quite some changes, but everything is limited to s390/zcrypt, means:
arch/
and
drivers/
- So everything is s390x specific.
- And larger parts of the changes are beautifications.
- It's all upstream accepted in 4.19
- The code is already successfully test, integrated and running in cosmic.
== Test Case ==
On an LPAR that has access to an CryptoExpress card,
execute the 'lszcrypt --verbose'
and check availability of:
/sys/bus/ap/apmask
General test and verification was already done by IBM.
Please notice that the code already landed in cosmic.
__________
With the introduction of KVM crypto virtualization the driver bound to an AP queue device is no longer unique determined.
This feature provides a deterministic hot plugging semantics of AP queues that may be bound to multiple drivers.
In particular it enables to configure an AP queue (APQN) as being bound to a particular driver even if the associate HW gets intermittently lost and reconnected.
This function has to be applied to kernel 4.15 for Ubuntu 18.04,
Git Commit information available here:
https:/
CVE References
| tags: | added: architecture-s39064 bugnameltc-172503 severity-high targetmilestone-inin1804 |
| Changed in ubuntu: | |
| assignee: | nobody → Skipper Bug Screeners (skipper-screen-team) |
| affects: | ubuntu → linux (Ubuntu) |
| Frank Heimes (fheimes) wrote | #1 |
| Changed in ubuntu-z-systems: | |
| status: | New → Triaged |
| importance: | Undecided → High |
| assignee: | nobody → Canonical Kernel Team (canonical-kernel-team) |
| information type: | Private → Public |
| Changed in linux (Ubuntu): | |
| status: | New → Triaged |
| importance: | Undecided → High |
| assignee: | Skipper Bug Screeners (skipper-screen-team) → Joseph Salisbury (jsalisbury) |
| Changed in linux (Ubuntu Bionic): | |
| status: | New → In Progress |
| Changed in linux (Ubuntu): | |
| status: | Triaged → In Progress |
| Changed in linux (Ubuntu Bionic): | |
| importance: | Undecided → High |
| assignee: | nobody → Joseph Salisbury (jsalisbury) |
| Changed in ubuntu-z-systems: | |
| status: | Triaged → In Progress |
| bugproxy (bugproxy) wrote Comment bridged from LTC Bugzilla | #2 |
| Joseph Salisbury (jsalisbury) wrote | #3 |
| description: | updated |
| description: | updated |
| Frank Heimes (fheimes) wrote | #5 |
| Changed in linux (Ubuntu Bionic): | |
| status: | In Progress → Fix Committed |
| Changed in linux (Ubuntu): | |
| status: | In Progress → Fix Committed |
| Changed in ubuntu-z-systems: | |
| status: | In Progress → Fix Committed |
| Brad Figg (brad-figg) wrote | #6 |
| tags: | added: verification-needed-bionic |
| Frank Heimes (fheimes) wrote | #7 |
| tags: |
added: verification-done-bionic removed: verification-needed-bionic |
| Launchpad Janitor (janitor) wrote | #8 |
| Changed in linux (Ubuntu Bionic): | |
| status: | Fix Committed → Fix Released |
| Frank Heimes (fheimes) wrote | #10 |
| Changed in linux (Ubuntu): | |
| status: | Fix Committed → Fix Released |
| Changed in ubuntu-z-systems: | |
| status: | Fix Committed → Fix Released |
| bugproxy (bugproxy) wrote | #11 |
| tags: | added: cscc |
| tags: | added: ssc |
According to
https:/
the three needed commits are:
1) Git-commit: ac2b96f351d7d222
s390/zcrypt: code beautify"
2) Git-commit 7e0bdbe5c21cb831
s390/zcrypt: AP bus support for alternate driver(s)"
3) Git-commit 3d8f60d38e249f98 s390/zcrypt:
hex string mask improvements for apmask and aqmask
Hope they cleanly apply to 4.15, too.