Messages in this thread | | | From | Nicolai Stange <> | Subject | Re: [PATCH v3 3/6] crypto: xts - drop redundant xts key check | Date | Thu, 05 Jan 2023 12:16:30 +0100 |
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Hi Vladis,
the patch subject prefix is a bit misleading IMO, it kind of suggests that this patch would apply to the generic crypto/xts.c. How about using a format similar to e.g. the one from commit 7988fb2c03c8 ("crypto: s390/aes - convert to skcipher API"), i.e.
"crypto: s390/aes - drop redundant xts key check"
?
Vladis Dronov <vdronov@redhat.com> writes:
> xts_fallback_setkey() in xts_aes_set_key() will now enforce key size > rule in FIPS mode when setting up the fallback algorithm keys,
I think it would be nice to make it more explicit why/how xts_fallback_setkey() happens to enforce the key size rules now.
Perhaps amend the above sentence by something like
"xts_fallback_setkey() in xts_aes_set_key() will now implictly enforce the key size rule in FIPS mode by means of invoking the generic xts implementation with its key checks for setting up the fallback algorithm,"
?
> which makes the check in xts_aes_set_key() redundant or > unreachable. So just drop this check. > > xts_fallback_setkey() now makes a key size check in xts_verify_key(): > > xts_fallback_setkey() > crypto_skcipher_setkey() [ skcipher_setkey_unaligned() ] > cipher->setkey() { .setkey = xts_setkey } > xts_setkey() > xts_verify_key() > > Signed-off-by: Vladis Dronov <vdronov@redhat.com> > --- > arch/s390/crypto/aes_s390.c | 4 ---- > 1 file changed, 4 deletions(-) > > diff --git a/arch/s390/crypto/aes_s390.c b/arch/s390/crypto/aes_s390.c > index 526c3f40f6a2..c773820e4af9 100644 > --- a/arch/s390/crypto/aes_s390.c > +++ b/arch/s390/crypto/aes_s390.c > @@ -398,10 +398,6 @@ static int xts_aes_set_key(struct crypto_skcipher *tfm, const u8 *in_key, > if (err) > return err; > > - /* In fips mode only 128 bit or 256 bit keys are valid */ > - if (fips_enabled && key_len != 32 && key_len != 64) > - return -EINVAL; > -
The change itself looks good, but it might be worth adding a comment right at the invocation of xts_fallback_setkey() that this includes an implicit xts_verify_key() check? So that if anybody ever was about to remove the xts_fallback_setkey() for some reason in the future, it would give a clear indication that xts_verify_key() needs to get called directly instead?
Thanks!
Nicolai
> /* Pick the correct function code based on the key length */ > fc = (key_len == 32) ? CPACF_KM_XTS_128 : > (key_len == 64) ? CPACF_KM_XTS_256 : 0;
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