Hi all,
the libkcapi [1] tests are failing on kernels 5.5-rc1 and above [2].
All encryption/decryption tests that use 'ctr(aes)' and a message size
that is not a multiple of 16 fail due to kcapi-enc returning different
output than expected.
It seems that it started with:
commit 5b0fe9552336338acb52756daf65dd7a4eeca73f
Author: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Date: Tue Sep 10 11:42:05 2019 +1000
crypto: algif_skcipher - Use chunksize instead of blocksize
Reverting the above commit makes the tests pass again.
Here is a one-line reproducer:
head -c 257 /dev/zero | kcapi-enc -vvv --pbkdfiter 1 -p "passwd" -s
"123" -e -c "ctr(aes)" --iv "0123456789abcdef0123456789abcdef"
>/dev/null
Output without revert:
[...]
libkcapi - Debug: AF_ALG: recvmsg syscall returned 256
kcapi-enc - Verbose: Removal of padding disabled
kcapi-enc - Verbose: 256 bytes of ciphertext created
Output with the revert and on older kernels:
[...]
libkcapi - Debug: AF_ALG: recvmsg syscall returned 257
kcapi-enc - Verbose: Removal of padding disabled
kcapi-enc - Verbose: 257 bytes of ciphertext created
I'm not familiar with the code in question, so I'm not sure if this is
a kernel bug or whether the change just exposed a bug in libkcapi.
Stephan, Herbert, can you please have a look?
Thanks,
Ondrej
[1] https://github.com/smuellerDD/libkcapi
[2] https://bugzilla.redhat.com/show_bug.cgi?id=1826022
