** Description changed:
[Impact]
* The Focal FIPS kernel in fips-updates hits kernel BUG/Oops
errors during boot with the FIPS OpenSSL library installed
(but those don't cause issues), when it runs modprobe with
request_module() when looking up crypto algorithms/modules.
* The modprobe command happens to call the OpenSSL library,
and the FIPS version of OpenSSL calls getrandom(),
and the FIPS kernel calls the DRBG for that,
BUT it's _not yet_ initialized that early during boot
when the kernel can run modprobe via request_module().
(e.g., IPv6 initialization time.)
* The issue impacts the kernels in fips-updates only, per:
"UBUNTU: SAUCE: random: Use Crypto API DRBG for urandom in FIPS mode"
which exists in Focal, but not in Xenial/Bionic/Jammy.
+ * The issue only happens with the crypto algorithms, even
+ if they're built-in (i.e., modprobe is not needed).
+
+
[Fix]
- * The issue only happens with the crypto algorithms, even
- if they're built-in (i.e., modprobe is not needed), so
- the fix approach is to set CRYPTO_NOLOAD while the DRBG
- isn't yet initialized; this skips request_module() calls.
+ * Fall back to CRNG while the DRBG is not yet initialized.
+ (Marcelo Cerri confirmed it's OK per other discussions.)
* The fix doesn't change the list and details of algorithms
as in /proc/crypto (e.g., name, driver, module, priority)
by the time the DRBG is initialized / initramfs started,
so even though behavior changes, the net effect doesn't.
* (Note: it's not possible to just use an initcall level
earlier than rootfs_initcall() so modprobe isn't there,
because fips_drbg_init() must run _after_ module_init()
level so that crypto_rng_reset() works, even though its
- required module is built-in too.
+ required module is built-in too.
[Test Steps]
* Install the kernel and openssl from fips-updates,
boot with fips=1, check dmesg for BUG/Oops errors:
$ sudo apt install linux-image-fips libssl1.1 # fips-updates
$ sudo vim /etc/default/grub # append fips=1 boot option
$ sudo update-grub && sudo reboot
$ sudo dmesg | grep BUG:
* Check/store the /proc/crypto file for comparisons.
You can boot with break=top as well, to check that
as early as possible, and copy into /run/initramfs/
then exit, to get it later in the rootfs.
[Regression Potential]
- * The fix skips calls to request_module()/modprobe on
- early boot until the FIPS DRBG is initialized (only
- in the crypto subsystem) thus potential regressions
- would show up as early boot kernel errors messages
- or crypto algorithms not up after system booted.
- (These should have no impact, theoretically, as it
- currently doesn't run anyway, because of BUG/Oops.)
-
- * The fix also adds a panic() call in request_module()
- if other/non-crypto kernel code attempts to load a
- module while the DRBG isn't ready yet (so we catch
- that earlier). It's possible to use a boot option
- to disable that behavior, but it disables FIPS mode
- for strictness.
+ * The fix falls back to the regular CRNG for a while
+ in early boot. The CRNG is used permanently in the
+ non-FIPS kernels (and in FIPS kernels w/out fips=1),
+ so the code path is exercised/tested frequently.
+
+ * Regressions would most likely occur in calls to
+ getrandom() before the DRBG is initialized, but
+ that currently hits a BUG/Oops anyway.
[Original Bug Description]
$ sudo apt install --yes linux-image-fips # fips-updates
$ sudo vim /etc/default/grub # fips=1
$ sudo update-grub && sudo reboot
$ uname -r
5.4.0-1056-fips
$ cat /proc/cmdline
... fips=1
No errors with the original/non-FIPS openssl, because it does NOT call
getrandom():
$ dmesg | grep -c BUG:
0
$ dpkg -s libssl1.1 | grep ^Version:
Version: 1.1.1f-1ubuntu2.15
$ strace -e getrandom modprobe --version
kmod version 27
+ZSTD +XZ -ZLIB +LIBCRYPTO -EXPERIMENTAL
+++ exited with 0 +++
But if you install the FIPS openssl, it calls getrandom(), then BUG/Oops
happen:
$ sudo apt install libssl1.1 # updates initramfs
$ dpkg -s libssl1.1 | grep ^Version:
Version: 1.1.1f-1ubuntu2.fips.13.1
$ strace -e getrandom modprobe --version
getrandom("\xc4\x84\x26\x25\x6f\xd4\xed\x38\xdf\xa9\x67\xee\x15\x1c\xe3\x98",
16, GRND_NONBLOCK) = 16
getrandom("\xa1\xd6\x67\x3e\xe4\x90\xb3\x8b\xdf\xe6\x34\x2a\xa7\x50\xbc\x2f",
16, GRND_NONBLOCK) = 16
getrandom("\xf1\x3e\xe4\x27\x9d\x47\x8c\x4b\x8a\x39\x8c\xe1\x2e\xee\xfa\x45",
16, GRND_NONBLOCK) = 16
getrandom("\xfb\x34\x18\x44\xd8\x23\x4c\x87\x13\x2e\x6b\x03\x79\xa7\x99\xf8",
16, 0) = 16
getrandom("\xdd\x83\xa7\x02\x10\x51\x2b\x4f\x21\x6b\xc1\xf1\x0d\xe7\x44\xb7",
16, 0) = 16
kmod version 27
+ZSTD +XZ -ZLIB +LIBCRYPTO -EXPERIMENTAL
+++ exited with 0 +++
$ sudo reboot
$ dmesg | grep -c BUG:
22
$ dmesg
...
[ 1.595759] NET: Registered protocol family 10
[ 1.600256] BUG: kernel NULL pointer dereference, address: 0000000000000038
...
[ 1.603829] CPU: 2 PID: 137 Comm: modprobe Not tainted 5.4.0-1056-fips
#64-Ubuntu
[ 1.603829] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
1.13.0-1ubuntu1.1 04/01/2014
[ 1.603829] RIP: 0010:urandom_read+0x268/0x480
...
[ 1.603829] Call Trace:
[ 1.603829] __x64_sys_getrandom+0x7f/0x130
[ 1.603829] do_syscall_64+0x57/0x190
[ 1.603829] entry_SYSCALL_64_after_hwframe+0x44/0xa9
...
All BUG/Oops errors are the same:
$ dmesg | grep BUG: | sed 's/^.*BUG:/BUG:/' | uniq -c
22 BUG: kernel NULL pointer dereference, address: 0000000000000038
And they stop after the DRBG is initialized:
[ 3.651566] random: DRBG (drbg_nopr_ctr_aes256) initialized!
[Fix Impact Analysis]
- The patches add 3 module options to configure the behavior
- of the components involved in the issue/fix. They can be
- seen with dynamic debug in the kernel cmdline:
+ The patch adds a dynamic debug message that can be enabled
+ in the kernel cmdline, for comparisons (dmesg); we can also
+ compare /proc/crypto for no changes.
- dyndbg="func crypto_alg_mod_lookup +p; func crypto_lookup_template +p;
- func __request_module +p"
+ dyndbg="func urandom_read +p"
Also add break=top, so we can copy /proc/crypto and dmesg
right after DRBG is initialized (when initramfs is started).
- Let's compare the 4 possible combination (first is 'no functional
- change'):
-
- random.fips_urandom_drbg_enable=0
- random.fips_urandom_drbg_crypto_noload=0
- random.fips_urandom_drbg_modprobe_panic=0
-
- random.fips_urandom_drbg_enable=1
- random.fips_urandom_drbg_crypto_noload=0
- random.fips_urandom_drbg_modprobe_panic=0
-
- random.fips_urandom_drbg_enable=1
- random.fips_urandom_drbg_crypto_noload=1
- random.fips_urandom_drbg_modprobe_panic=0
-
- random.fips_urandom_drbg_enable=1
- random.fips_urandom_drbg_crypto_noload=1
- random.fips_urandom_drbg_modprobe_panic=1
-
@ break=top time
- enable=$(cat /sys/module/random/parameters/fips_urandom_drbg_enable)
- noload=$(cat /sys/module/random/parameters/fips_urandom_drbg_crypto_noload)
- panic=$(cat /sys/module/random/parameters/fips_urandom_drbg_modprobe_panic)
- suffix="enable${enable}_noload${noload}_panic${panic}"
-
+ suffix=original # or modified
cat /proc/crypto > /run/initramfs/proc-crypto.$suffix
dmesg > /run/initramfs/dmesg.$suffix
-
exit
@ login time
sudo -s
cp /run/initramfs/{proc-crypto.*,dmesg.*} .
- reboot # next possible combination
+ reboot # next test
There's no difference in the list/details of loaded crypto algorithms at
all, with any combination:
- # md5sum proc-crypto.enable*_noload*_panic*
- 0b91bd619078fa342c6b4da039cb1582 proc-crypto.enableN_noloadN_panicN
- 0b91bd619078fa342c6b4da039cb1582 proc-crypto.enableY_noloadN_panicN
- 0b91bd619078fa342c6b4da039cb1582 proc-crypto.enableY_noloadY_panicN
- 0b91bd619078fa342c6b4da039cb1582 proc-crypto.enableY_noloadY_panicY
+ # md5sum proc-crypto.*
+ 0b91bd619078fa342c6b4da039cb1582 proc-crypto.modified
+ 0b91bd619078fa342c6b4da039cb1582 proc-crypto.original
- The only option that hits BUG/Oops errors is when you disable the fix
- (ie, don't set CRYPTO_NOLOAD):
+ The kernel with the fix does not hit BUG/Oops errors:
- # grep -c BUG: dmesg.enable*_noload*_panic*
- dmesg.enableN_noloadN_panicN:0
- dmesg.enableY_noloadN_panicN:22
- dmesg.enableY_noloadY_panicN:0
- dmesg.enableY_noloadY_panicY:0
+ # grep ^ -m1 dmesg.*
+ dmesg.modified:[ 0.000000] Linux version 5.4.0-1060-fips ...
#68+fipsdrbgnullcheck ... (Ubuntu 5.4.0-1060.68+fipsdrbgnullcheck-fips 5.4.195)
+ dmesg.original:[ 0.000000] Linux version 5.4.0-1060-fips ... #68-Ubuntu
... (Ubuntu 5.4.0-1060.68-fips 5.4.195)
+
+ # grep -c BUG: dmesg.*
+ dmesg.modified:0
+ dmesg.original:22
+
+ # grep -c 'random: DRBG uninitialized! crng fallback' dmesg.*
+ dmesg.modified:110
+ dmesg.original:0
+
+ The 110 number is 5 * 22 calls as modprobe calls getrandom() 5 times (see
strace above).
+ The original kernel has 1 BUG/Oops only because that kills the modprobe task.
** Description changed:
[Impact]
* The Focal FIPS kernel in fips-updates hits kernel BUG/Oops
errors during boot with the FIPS OpenSSL library installed
(but those don't cause issues), when it runs modprobe with
request_module() when looking up crypto algorithms/modules.
* The modprobe command happens to call the OpenSSL library,
and the FIPS version of OpenSSL calls getrandom(),
and the FIPS kernel calls the DRBG for that,
BUT it's _not yet_ initialized that early during boot
when the kernel can run modprobe via request_module().
(e.g., IPv6 initialization time.)
* The issue impacts the kernels in fips-updates only, per:
"UBUNTU: SAUCE: random: Use Crypto API DRBG for urandom in FIPS mode"
which exists in Focal, but not in Xenial/Bionic/Jammy.
* The issue only happens with the crypto algorithms, even
if they're built-in (i.e., modprobe is not needed).
-
[Fix]
* Fall back to CRNG while the DRBG is not yet initialized.
- (Marcelo Cerri confirmed it's OK per other discussions.)
+ (Marcelo Cerri confirmed it's OK per other discussions.)
* The fix doesn't change the list and details of algorithms
as in /proc/crypto (e.g., name, driver, module, priority)
by the time the DRBG is initialized / initramfs started,
so even though behavior changes, the net effect doesn't.
* (Note: it's not possible to just use an initcall level
earlier than rootfs_initcall() so modprobe isn't there,
because fips_drbg_init() must run _after_ module_init()
level so that crypto_rng_reset() works, even though its
required module is built-in too.
[Test Steps]
* Install the kernel and openssl from fips-updates,
boot with fips=1, check dmesg for BUG/Oops errors:
$ sudo apt install linux-image-fips libssl1.1 # fips-updates
$ sudo vim /etc/default/grub # append fips=1 boot option
$ sudo update-grub && sudo reboot
$ sudo dmesg | grep BUG:
* Check/store the /proc/crypto file for comparisons.
You can boot with break=top as well, to check that
as early as possible, and copy into /run/initramfs/
then exit, to get it later in the rootfs.
[Regression Potential]
* The fix falls back to the regular CRNG for a while
- in early boot. The CRNG is used permanently in the
- non-FIPS kernels (and in FIPS kernels w/out fips=1),
- so the code path is exercised/tested frequently.
-
+ in early boot. The CRNG is used permanently in the
+ non-FIPS kernels (and in FIPS kernels w/out fips=1),
+ so the code path is exercised/tested frequently.
+
* Regressions would most likely occur in calls to
- getrandom() before the DRBG is initialized, but
- that currently hits a BUG/Oops anyway.
+ getrandom() before the DRBG is initialized, but
+ that currently hits a BUG/Oops anyway.
[Original Bug Description]
$ sudo apt install --yes linux-image-fips # fips-updates
$ sudo vim /etc/default/grub # fips=1
$ sudo update-grub && sudo reboot
$ uname -r
5.4.0-1056-fips
$ cat /proc/cmdline
... fips=1
No errors with the original/non-FIPS openssl, because it does NOT call
getrandom():
$ dmesg | grep -c BUG:
0
$ dpkg -s libssl1.1 | grep ^Version:
Version: 1.1.1f-1ubuntu2.15
$ strace -e getrandom modprobe --version
kmod version 27
+ZSTD +XZ -ZLIB +LIBCRYPTO -EXPERIMENTAL
+++ exited with 0 +++
But if you install the FIPS openssl, it calls getrandom(), then BUG/Oops
happen:
$ sudo apt install libssl1.1 # updates initramfs
$ dpkg -s libssl1.1 | grep ^Version:
Version: 1.1.1f-1ubuntu2.fips.13.1
$ strace -e getrandom modprobe --version
getrandom("\xc4\x84\x26\x25\x6f\xd4\xed\x38\xdf\xa9\x67\xee\x15\x1c\xe3\x98",
16, GRND_NONBLOCK) = 16
getrandom("\xa1\xd6\x67\x3e\xe4\x90\xb3\x8b\xdf\xe6\x34\x2a\xa7\x50\xbc\x2f",
16, GRND_NONBLOCK) = 16
getrandom("\xf1\x3e\xe4\x27\x9d\x47\x8c\x4b\x8a\x39\x8c\xe1\x2e\xee\xfa\x45",
16, GRND_NONBLOCK) = 16
getrandom("\xfb\x34\x18\x44\xd8\x23\x4c\x87\x13\x2e\x6b\x03\x79\xa7\x99\xf8",
16, 0) = 16
getrandom("\xdd\x83\xa7\x02\x10\x51\x2b\x4f\x21\x6b\xc1\xf1\x0d\xe7\x44\xb7",
16, 0) = 16
kmod version 27
+ZSTD +XZ -ZLIB +LIBCRYPTO -EXPERIMENTAL
+++ exited with 0 +++
$ sudo reboot
$ dmesg | grep -c BUG:
22
$ dmesg
...
[ 1.595759] NET: Registered protocol family 10
[ 1.600256] BUG: kernel NULL pointer dereference, address: 0000000000000038
...
[ 1.603829] CPU: 2 PID: 137 Comm: modprobe Not tainted 5.4.0-1056-fips
#64-Ubuntu
[ 1.603829] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
1.13.0-1ubuntu1.1 04/01/2014
[ 1.603829] RIP: 0010:urandom_read+0x268/0x480
...
[ 1.603829] Call Trace:
[ 1.603829] __x64_sys_getrandom+0x7f/0x130
[ 1.603829] do_syscall_64+0x57/0x190
[ 1.603829] entry_SYSCALL_64_after_hwframe+0x44/0xa9
...
All BUG/Oops errors are the same:
$ dmesg | grep BUG: | sed 's/^.*BUG:/BUG:/' | uniq -c
22 BUG: kernel NULL pointer dereference, address: 0000000000000038
And they stop after the DRBG is initialized:
[ 3.651566] random: DRBG (drbg_nopr_ctr_aes256) initialized!
[Fix Impact Analysis]
The patch adds a dynamic debug message that can be enabled
in the kernel cmdline, for comparisons (dmesg); we can also
compare /proc/crypto for no changes.
dyndbg="func urandom_read +p"
Also add break=top, so we can copy /proc/crypto and dmesg
right after DRBG is initialized (when initramfs is started).
@ break=top time
- suffix=original # or modified
+ suffix=original # or modified
cat /proc/crypto > /run/initramfs/proc-crypto.$suffix
dmesg > /run/initramfs/dmesg.$suffix
exit
@ login time
sudo -s
cp /run/initramfs/{proc-crypto.*,dmesg.*} .
reboot # next test
There's no difference in the list/details of loaded crypto algorithms at
all, with any combination:
# md5sum proc-crypto.*
0b91bd619078fa342c6b4da039cb1582 proc-crypto.modified
0b91bd619078fa342c6b4da039cb1582 proc-crypto.original
The kernel with the fix does not hit BUG/Oops errors:
# grep ^ -m1 dmesg.*
- dmesg.modified:[ 0.000000] Linux version 5.4.0-1060-fips ...
#68+fipsdrbgnullcheck ... (Ubuntu 5.4.0-1060.68+fipsdrbgnullcheck-fips 5.4.195)
- dmesg.original:[ 0.000000] Linux version 5.4.0-1060-fips ... #68-Ubuntu
... (Ubuntu 5.4.0-1060.68-fips 5.4.195)
+ dmesg.modified:[ 0.000000] Linux version 5.4.0-1060-fips ...
#68+fipsdrbgnullcheck ...
+ dmesg.original:[ 0.000000] Linux version 5.4.0-1060-fips ... #68-Ubuntu ...
# grep -c BUG: dmesg.*
dmesg.modified:0
dmesg.original:22
# grep -c 'random: DRBG uninitialized! crng fallback' dmesg.*
dmesg.modified:110
dmesg.original:0
The 110 number is 5 * 22 calls as modprobe calls getrandom() 5 times (see
strace above).
The original kernel has 1 BUG/Oops only because that kills the modprobe task.
--
You received this bug notification because you are a member of Kernel
Packages, which is subscribed to linux in Ubuntu.
https://bugs.launchpad.net/bugs/1981487
Title:
kernel BUG/Oops errors from modprobe while the DRBG has not yet
initialized (focal/fips-updates)
Status in linux package in Ubuntu:
Invalid
Status in linux source package in Bionic:
Invalid
Status in linux source package in Focal:
In Progress
Status in linux source package in Jammy:
Invalid
Bug description:
[Impact]
* The Focal FIPS kernel in fips-updates hits kernel BUG/Oops
errors during boot with the FIPS OpenSSL library installed
(but those don't cause issues), when it runs modprobe with
request_module() when looking up crypto algorithms/modules.
* The modprobe command happens to call the OpenSSL library,
and the FIPS version of OpenSSL calls getrandom(),
and the FIPS kernel calls the DRBG for that,
BUT it's _not yet_ initialized that early during boot
when the kernel can run modprobe via request_module().
(e.g., IPv6 initialization time.)
* The issue impacts the kernels in fips-updates only, per:
"UBUNTU: SAUCE: random: Use Crypto API DRBG for urandom in FIPS mode"
which exists in Focal, but not in Xenial/Bionic/Jammy.
* The issue only happens with the crypto algorithms, even
if they're built-in (i.e., modprobe is not needed).
[Fix]
* Fall back to CRNG while the DRBG is not yet initialized.
(Marcelo Cerri confirmed it's OK per other discussions.)
* The fix doesn't change the list and details of algorithms
as in /proc/crypto (e.g., name, driver, module, priority)
by the time the DRBG is initialized / initramfs started,
so even though behavior changes, the net effect doesn't.
* (Note: it's not possible to just use an initcall level
earlier than rootfs_initcall() so modprobe isn't there,
because fips_drbg_init() must run _after_ module_init()
level so that crypto_rng_reset() works, even though its
required module is built-in too.
[Test Steps]
* Install the kernel and openssl from fips-updates,
boot with fips=1, check dmesg for BUG/Oops errors:
$ sudo apt install linux-image-fips libssl1.1 # fips-updates
$ sudo vim /etc/default/grub # append fips=1 boot option
$ sudo update-grub && sudo reboot
$ sudo dmesg | grep BUG:
* Check/store the /proc/crypto file for comparisons.
You can boot with break=top as well, to check that
as early as possible, and copy into /run/initramfs/
then exit, to get it later in the rootfs.
[Regression Potential]
* The fix falls back to the regular CRNG for a while
in early boot. The CRNG is used permanently in the
non-FIPS kernels (and in FIPS kernels w/out fips=1),
so the code path is exercised/tested frequently.
* Regressions would most likely occur in calls to
getrandom() before the DRBG is initialized, but
that currently hits a BUG/Oops anyway.
[Original Bug Description]
$ sudo apt install --yes linux-image-fips # fips-updates
$ sudo vim /etc/default/grub # fips=1
$ sudo update-grub && sudo reboot
$ uname -r
5.4.0-1056-fips
$ cat /proc/cmdline
... fips=1
No errors with the original/non-FIPS openssl, because it does NOT call
getrandom():
$ dmesg | grep -c BUG:
0
$ dpkg -s libssl1.1 | grep ^Version:
Version: 1.1.1f-1ubuntu2.15
$ strace -e getrandom modprobe --version
kmod version 27
+ZSTD +XZ -ZLIB +LIBCRYPTO -EXPERIMENTAL
+++ exited with 0 +++
But if you install the FIPS openssl, it calls getrandom(), then
BUG/Oops happen:
$ sudo apt install libssl1.1 # updates initramfs
$ dpkg -s libssl1.1 | grep ^Version:
Version: 1.1.1f-1ubuntu2.fips.13.1
$ strace -e getrandom modprobe --version
getrandom("\xc4\x84\x26\x25\x6f\xd4\xed\x38\xdf\xa9\x67\xee\x15\x1c\xe3\x98",
16, GRND_NONBLOCK) = 16
getrandom("\xa1\xd6\x67\x3e\xe4\x90\xb3\x8b\xdf\xe6\x34\x2a\xa7\x50\xbc\x2f",
16, GRND_NONBLOCK) = 16
getrandom("\xf1\x3e\xe4\x27\x9d\x47\x8c\x4b\x8a\x39\x8c\xe1\x2e\xee\xfa\x45",
16, GRND_NONBLOCK) = 16
getrandom("\xfb\x34\x18\x44\xd8\x23\x4c\x87\x13\x2e\x6b\x03\x79\xa7\x99\xf8",
16, 0) = 16
getrandom("\xdd\x83\xa7\x02\x10\x51\x2b\x4f\x21\x6b\xc1\xf1\x0d\xe7\x44\xb7",
16, 0) = 16
kmod version 27
+ZSTD +XZ -ZLIB +LIBCRYPTO -EXPERIMENTAL
+++ exited with 0 +++
$ sudo reboot
$ dmesg | grep -c BUG:
22
$ dmesg
...
[ 1.595759] NET: Registered protocol family 10
[ 1.600256] BUG: kernel NULL pointer dereference, address: 0000000000000038
...
[ 1.603829] CPU: 2 PID: 137 Comm: modprobe Not tainted 5.4.0-1056-fips
#64-Ubuntu
[ 1.603829] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
1.13.0-1ubuntu1.1 04/01/2014
[ 1.603829] RIP: 0010:urandom_read+0x268/0x480
...
[ 1.603829] Call Trace:
[ 1.603829] __x64_sys_getrandom+0x7f/0x130
[ 1.603829] do_syscall_64+0x57/0x190
[ 1.603829] entry_SYSCALL_64_after_hwframe+0x44/0xa9
...
All BUG/Oops errors are the same:
$ dmesg | grep BUG: | sed 's/^.*BUG:/BUG:/' | uniq -c
22 BUG: kernel NULL pointer dereference, address: 0000000000000038
And they stop after the DRBG is initialized:
[ 3.651566] random: DRBG (drbg_nopr_ctr_aes256) initialized!
[Fix Impact Analysis]
The patch adds a dynamic debug message that can be enabled
in the kernel cmdline, for comparisons (dmesg); we can also
compare /proc/crypto for no changes.
dyndbg="func urandom_read +p"
Also add break=top, so we can copy /proc/crypto and dmesg
right after DRBG is initialized (when initramfs is started).
@ break=top time
suffix=original # or modified
cat /proc/crypto > /run/initramfs/proc-crypto.$suffix
dmesg > /run/initramfs/dmesg.$suffix
exit
@ login time
sudo -s
cp /run/initramfs/{proc-crypto.*,dmesg.*} .
reboot # next test
There's no difference in the list/details of loaded crypto algorithms
at all, with any combination:
# md5sum proc-crypto.*
0b91bd619078fa342c6b4da039cb1582 proc-crypto.modified
0b91bd619078fa342c6b4da039cb1582 proc-crypto.original
The kernel with the fix does not hit BUG/Oops errors:
# grep ^ -m1 dmesg.*
dmesg.modified:[ 0.000000] Linux version 5.4.0-1060-fips ...
#68+fipsdrbgnullcheck ...
dmesg.original:[ 0.000000] Linux version 5.4.0-1060-fips ... #68-Ubuntu ...
# grep -c BUG: dmesg.*
dmesg.modified:0
dmesg.original:22
# grep -c 'random: DRBG uninitialized! crng fallback' dmesg.*
dmesg.modified:110
dmesg.original:0
The 110 number is 5 * 22 calls as modprobe calls getrandom() 5 times (see
strace above).
The original kernel has 1 BUG/Oops only because that kills the modprobe task.
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