crypto_alloc_blkcipher() can't find the ctr(aes) cipher in Ubuntu 20.04LTS

ddsdds

During a port of our DKMS kernel module from Linux kernel 4.19 to 5.4, ran into the following issue.

Exact Linux versions used for the port:

4.19: Debian 10 (buster) 4.19.0-25-amd64 #1 SMP Debian 4.19.289-2 (2023-08-08) x86_64 GNU/Linux

5.4: Ubuntu 20.04 LTS 5.4.0-216-generic #236-Ubuntu SMP

Both are standard installs.
The following function produces an error in 5.4:

**tfm = crypto_alloc_blkcipher("ctr(aes)", 0, 128);**

This same exact code runs fine and without errors in 4.19, whereas in 5.4 it returns an error. In 5.4 IS_ERR(tfm) evaluates to TRUE, and PTR_ERR(tfm) evaluates to -2, which usually corresponds to ENOENT, "No such file or directory".

As far as I can tell, this part of the Crypto API did not change from 4.19 to 5.4.

I can see that in addition to some wrappers, crypto_alloc_blkcipher() uses the following three Crypto API functions: crypto_alg_mod_lookup(alg_name, type, mask), __crypto_alloc_tfm(alg, type, mask), and crypto_mod_put(alg), but all these are "internal" API functions, and I don't see a straightforward way to call them from my kernel module directly, to see which one of these produces the error. The standard install does not include the necessary crypto/internal.h.

From the Crypto API documentation: "The synchronous block cipher API is used with the ciphers of type CRYPTO_ALG_TYPE_BLKCIPHER (listed as type “blkcipher” in /proc/crypto)"

My best guess is that the block version of ctr(aes) is missing from 5.4.

Looking at /proc/crypto, the ctr(aes) sections are as follows:
4.19:
name : ctr(aes)
driver : ctr(aes-aesni)
module : ctr
priority : 300
refcnt : 9
selftest : passed
internal : no
type : blkcipher
blocksize : 1
min keysize : 16
max keysize : 32
ivsize : 16
geniv : chainiv

    5.4:

name : ctr(aes)
driver : ctr-aes-aesni
module : aesni_intel
priority : 400
refcnt : 1
selftest : passed
internal : no
type : skcipher
async : yes
blocksize : 1
min keysize : 16
max keysize : 32
ivsize : 16
chunksize : 16
walksize : 16

It looks like in 5.4 the ctr(aes) cipher is listed as skcipher rather than blkcipher

So how do I install a ctr(aes) cipher of 'blkcipher' type in Ubuntu 20.04LTS?

Thank you.