| 9ebfa8dc | 02-May-2025 |
Coiby Xu <coxu@redhat.com> |
crash_dump: reuse saved dm crypt keys for CPU/memory hot-plugging
When there are CPU and memory hot un/plugs, the dm crypt keys may need to
be reloaded again depending on the solution for crash hotp
crash_dump: reuse saved dm crypt keys for CPU/memory hot-plugging
When there are CPU and memory hot un/plugs, the dm crypt keys may need to
be reloaded again depending on the solution for crash hotplug support.
Currently, there are two solutions. One is to utilizes udev to instruct
user space to reload the kdump kernel image and initrd, elfcorehdr and etc
again. The other is to only update the elfcorehdr segment introduced in
commit 247262756121 ("crash: add generic infrastructure for crash hotplug
support").
For the 1st solution, the dm crypt keys need to be reloaded again. The
user space can write true to /sys/kernel/config/crash_dm_crypt_key/reuse
so the stored keys can be re-used.
For the 2nd solution, the dm crypt keys don't need to be reloaded.
Currently, only x86 supports the 2nd solution. If the 2nd solution gets
extended to all arches, this patch can be dropped.
Link: https://lkml.kernel.org/r/20250502011246.99238-5-coxu@redhat.com
Signed-off-by: Coiby Xu <coxu@redhat.com>
Acked-by: Baoquan He <bhe@redhat.com>
Cc: "Daniel P. Berrange" <berrange@redhat.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Jan Pazdziora <jpazdziora@redhat.com>
Cc: Liu Pingfan <kernelfans@gmail.com>
Cc: Milan Broz <gmazyland@gmail.com>
Cc: Ondrej Kozina <okozina@redhat.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
show more ...
|
| 180cf31a | 02-May-2025 |
Coiby Xu <coxu@redhat.com> |
crash_dump: make dm crypt keys persist for the kdump kernel
A configfs /sys/kernel/config/crash_dm_crypt_keys is provided for user
space to make the dm crypt keys persist for the kdump kernel. Take
crash_dump: make dm crypt keys persist for the kdump kernel
A configfs /sys/kernel/config/crash_dm_crypt_keys is provided for user
space to make the dm crypt keys persist for the kdump kernel. Take the
case of dumping to a LUKS-encrypted target as an example, here is the life
cycle of the kdump copies of LUKS volume keys,
1. After the 1st kernel loads the initramfs during boot, systemd uses
an user-input passphrase to de-crypt the LUKS volume keys or simply
TPM-sealed volume keys and then save the volume keys to specified
keyring (using the --link-vk-to-keyring API) and the keys will expire
within specified time.
2. A user space tool (kdump initramfs loader like kdump-utils) create
key items inside /sys/kernel/config/crash_dm_crypt_keys to inform
the 1st kernel which keys are needed.
3. When the kdump initramfs is loaded by the kexec_file_load
syscall, the 1st kernel will iterate created key items, save the
keys to kdump reserved memory.
4. When the 1st kernel crashes and the kdump initramfs is booted, the
kdump initramfs asks the kdump kernel to create a user key using the
key stored in kdump reserved memory by writing yes to
/sys/kernel/crash_dm_crypt_keys/restore. Then the LUKS encrypted
device is unlocked with libcryptsetup's --volume-key-keyring API.
5. The system gets rebooted to the 1st kernel after dumping vmcore to
the LUKS encrypted device is finished
Eventually the keys have to stay in the kdump reserved memory for the
kdump kernel to unlock encrypted volumes. During this process, some
measures like letting the keys expire within specified time are desirable
to reduce security risk.
This patch assumes,
1) there are 128 LUKS devices at maximum to be unlocked thus
MAX_KEY_NUM=128.
2) a key description won't exceed 128 bytes thus KEY_DESC_MAX_LEN=128.
And here is a demo on how to interact with
/sys/kernel/config/crash_dm_crypt_keys,
# Add key #1
mkdir /sys/kernel/config/crash_dm_crypt_keys/7d26b7b4-e342-4d2d-b660-7426b0996720
# Add key #1's description
echo cryptsetup:7d26b7b4-e342-4d2d-b660-7426b0996720 > /sys/kernel/config/crash_dm_crypt_keys/description
# how many keys do we have now?
cat /sys/kernel/config/crash_dm_crypt_keys/count
1
# Add key# 2 in the same way
# how many keys do we have now?
cat /sys/kernel/config/crash_dm_crypt_keys/count
2
# the tree structure of /crash_dm_crypt_keys configfs
tree /sys/kernel/config/crash_dm_crypt_keys/
/sys/kernel/config/crash_dm_crypt_keys/
├── 7d26b7b4-e342-4d2d-b660-7426b0996720
│ └── description
├── count
├── fce2cd38-4d59-4317-8ce2-1fd24d52c46a
│ └── description
Link: https://lkml.kernel.org/r/20250502011246.99238-3-coxu@redhat.com
Signed-off-by: Coiby Xu <coxu@redhat.com>
Acked-by: Baoquan He <bhe@redhat.com>
Cc: "Daniel P. Berrange" <berrange@redhat.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Jan Pazdziora <jpazdziora@redhat.com>
Cc: Liu Pingfan <kernelfans@gmail.com>
Cc: Milan Broz <gmazyland@gmail.com>
Cc: Ondrej Kozina <okozina@redhat.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
show more ...
|
| de53c05f | 16-Aug-2023 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
mm: add large_rmappable page flag
Stored in the first tail page's flags, this flag replaces the destructor.
That removes the last of the destructors, so remove all references to
folio_dtor and comp
mm: add large_rmappable page flag
Stored in the first tail page's flags, this flag replaces the destructor.
That removes the last of the destructors, so remove all references to
folio_dtor and compound_dtor.
Link: https://lkml.kernel.org/r/20230816151201.3655946-9-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: Yanteng Si <siyanteng@loongson.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
show more ...
|