On Tue, 2 Jul 2019 at 23:55, Eric Biggers <ebiggers@xxxxxxxxxx> wrote:
>
> Hi Ard,
>
> On Tue, Jul 02, 2019 at 06:48:10PM +0200, Ard Biesheuvel wrote:
> > Instead of open coding the calculations for ESSIV handling, use a
> > ESSIV skcipher which does all of this under the hood.
> >
> > Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
> > ---
> > fs/crypto/Kconfig | 1 +
> > fs/crypto/crypto.c | 5 --
> > fs/crypto/fscrypt_private.h | 9 --
> > fs/crypto/keyinfo.c | 95 +-------------------
> > 4 files changed, 5 insertions(+), 105 deletions(-)
> >
> > diff --git a/fs/crypto/Kconfig b/fs/crypto/Kconfig
> > index 24ed99e2eca0..b0292da8613c 100644
> > --- a/fs/crypto/Kconfig
> > +++ b/fs/crypto/Kconfig
> > @@ -5,6 +5,7 @@ config FS_ENCRYPTION
> > select CRYPTO_AES
> > select CRYPTO_CBC
> > select CRYPTO_ECB
> > + select CRYPTO_ESSIV
> > select CRYPTO_XTS
> > select CRYPTO_CTS
> > select CRYPTO_SHA256
> > diff --git a/fs/crypto/crypto.c b/fs/crypto/crypto.c
> > index 335a362ee446..c53ce262a06c 100644
> > --- a/fs/crypto/crypto.c
> > +++ b/fs/crypto/crypto.c
> > @@ -136,9 +136,6 @@ void fscrypt_generate_iv(union fscrypt_iv *iv, u64 lblk_num,
> >
> > if (ci->ci_flags & FS_POLICY_FLAG_DIRECT_KEY)
> > memcpy(iv->nonce, ci->ci_nonce, FS_KEY_DERIVATION_NONCE_SIZE);
> > -
> > - if (ci->ci_essiv_tfm != NULL)
> > - crypto_cipher_encrypt_one(ci->ci_essiv_tfm, iv->raw, iv->raw);
> > }
> >
> > int fscrypt_do_page_crypto(const struct inode *inode, fscrypt_direction_t rw,
> > @@ -492,8 +489,6 @@ static void __exit fscrypt_exit(void)
> > destroy_workqueue(fscrypt_read_workqueue);
> > kmem_cache_destroy(fscrypt_ctx_cachep);
> > kmem_cache_destroy(fscrypt_info_cachep);
> > -
> > - fscrypt_essiv_cleanup();
> > }
> > module_exit(fscrypt_exit);
> >
> > diff --git a/fs/crypto/fscrypt_private.h b/fs/crypto/fscrypt_private.h
> > index 7da276159593..59d0cba9cfb9 100644
> > --- a/fs/crypto/fscrypt_private.h
> > +++ b/fs/crypto/fscrypt_private.h
> > @@ -61,12 +61,6 @@ struct fscrypt_info {
> > /* The actual crypto transform used for encryption and decryption */
> > struct crypto_skcipher *ci_ctfm;
> >
> > - /*
> > - * Cipher for ESSIV IV generation. Only set for CBC contents
> > - * encryption, otherwise is NULL.
> > - */
> > - struct crypto_cipher *ci_essiv_tfm;
> > -
> > /*
> > * Encryption mode used for this inode. It corresponds to either
> > * ci_data_mode or ci_filename_mode, depending on the inode type.
> > @@ -166,9 +160,6 @@ struct fscrypt_mode {
> > int keysize;
> > int ivsize;
> > bool logged_impl_name;
> > - bool needs_essiv;
> > };
> >
> > -extern void __exit fscrypt_essiv_cleanup(void);
> > -
> > #endif /* _FSCRYPT_PRIVATE_H */
> > diff --git a/fs/crypto/keyinfo.c b/fs/crypto/keyinfo.c
> > index dcd91a3fbe49..f39667d4316a 100644
> > --- a/fs/crypto/keyinfo.c
> > +++ b/fs/crypto/keyinfo.c
> > @@ -13,14 +13,10 @@
> > #include <linux/hashtable.h>
> > #include <linux/scatterlist.h>
> > #include <linux/ratelimit.h>
> > -#include <crypto/aes.h>
> > #include <crypto/algapi.h>
> > -#include <crypto/sha.h>
> > #include <crypto/skcipher.h>
> > #include "fscrypt_private.h"
> >
> > -static struct crypto_shash *essiv_hash_tfm;
> > -
> > /* Table of keys referenced by FS_POLICY_FLAG_DIRECT_KEY policies */
> > static DEFINE_HASHTABLE(fscrypt_master_keys, 6); /* 6 bits = 64 buckets */
> > static DEFINE_SPINLOCK(fscrypt_master_keys_lock);
> > @@ -144,10 +140,9 @@ static struct fscrypt_mode available_modes[] = {
> > },
> > [FS_ENCRYPTION_MODE_AES_128_CBC] = {
> > .friendly_name = "AES-128-CBC",
> > - .cipher_str = "cbc(aes)",
> > + .cipher_str = "essiv(cbc(aes),aes,sha256)",
> > .keysize = 16,
> > - .ivsize = 16,
> > - .needs_essiv = true,
> > + .ivsize = 8,
>
> As I said before, this needs to be kept as .ivsize = 16.
>
> This bug actually causes the generic/549 test to fail.
>
Ugh, yes, I intended to fix that. Apologies for the sloppiness, I have
been trying to wrap this up in time for my holidays, but the end
result is quite the opposite :-)
> Otherwise this patch looks good. FYI: to avoid conflicts with planned fscrypt
> work I'd prefer to take this patch through the fscrypt.git tree after the ESSIV
> template is merged, rather than have Herbert take it through cryptodev. (Unless
> he's going to apply this whole series for v5.3, in which case I'm fine with him
> taking the fscrypt patch too, though it seems too late for that.)
>
I agree that the fscrypt and dm-crypt changes should not be merged for v5.3
I know that Herbert typically prefers not to take any new code without
any of its users, but perhaps we can make an exception in this case,
and merge patches #1, #5, #6 and #7 now (which is mostly risk free
since no code uses essiv yet, and patch #5 is a straight-forward
refactor) and take the fscrypt and dm-crypt patches through their
respective trees for the next cycle.
