Re: Patch "libceph: introduce ceph_crypt() for in-place en/decryption" has been added to the 4.9-stable tree

[Greg KH <gregkh@linuxfoundation.org>]

On Fri, Jan 20, 2017 at 04:05:04PM +0100, Ilya Dryomov wrote:
> On Fri, Jan 20, 2017 at 3:53 PM,  <gregkh@linuxfoundation.org> wrote:
> >
> > This is a note to let you know that I've just added the patch titled
> >
> >     libceph: introduce ceph_crypt() for in-place en/decryption
> >
> > to the 4.9-stable tree which can be found at:
> >     http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
> >
> > The filename of the patch is:
> >      libceph-introduce-ceph_crypt-for-in-place-en-decryption.patch
> > and it can be found in the queue-4.9 subdirectory.
> >
> > If you, or anyone else, feels it should not be added to the stable tree,
> > please let <stable@vger.kernel.org> know about it.
> >
> >
> > From a45f795c65b479b4ba107b6ccde29b896d51ee98 Mon Sep 17 00:00:00 2001
> > From: Ilya Dryomov <idryomov@gmail.com>
> > Date: Fri, 2 Dec 2016 16:35:07 +0100
> > Subject: libceph: introduce ceph_crypt() for in-place en/decryption
> >
> > From: Ilya Dryomov <idryomov@gmail.com>
> >
> > commit a45f795c65b479b4ba107b6ccde29b896d51ee98 upstream.
> >
> > Starting with 4.9, kernel stacks may be vmalloced and therefore not
> > guaranteed to be physically contiguous; the new CONFIG_VMAP_STACK
> > option is enabled by default on x86.  This makes it invalid to use
> > on-stack buffers with the crypto scatterlist API, as sg_set_buf()
> > expects a logical address and won't work with vmalloced addresses.
> >
> > There isn't a different (e.g. kvec-based) crypto API we could switch
> > net/ceph/crypto.c to and the current scatterlist.h API isn't getting
> > updated to accommodate this use case.  Allocating a new header and
> > padding for each operation is a non-starter, so do the en/decryption
> > in-place on a single pre-assembled (header + data + padding) heap
> > buffer.  This is explicitly supported by the crypto API:
> >
> >     "... the caller may provide the same scatter/gather list for the
> >      plaintext and cipher text. After the completion of the cipher
> >      operation, the plaintext data is replaced with the ciphertext data
> >      in case of an encryption and vice versa for a decryption."
> >
> > Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
> > Reviewed-by: Sage Weil <sage@redhat.com>
> > Cc: Brad Spengler <spender@grsecurity.net>
> > Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> >
> > ---
> >  net/ceph/crypto.c |   87 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
> >  net/ceph/crypto.h |    2 +
> >  2 files changed, 89 insertions(+)
> >
> > --- a/net/ceph/crypto.c
> > +++ b/net/ceph/crypto.c
> > @@ -526,6 +526,93 @@ int ceph_encrypt2(struct ceph_crypto_key
> >         }
> >  }
> >
> > +static int ceph_aes_crypt(const struct ceph_crypto_key *key, bool encrypt,
> > +                         void *buf, int buf_len, int in_len, int *pout_len)
> > +{
> > +       struct crypto_skcipher *tfm = ceph_crypto_alloc_cipher();
> > +       SKCIPHER_REQUEST_ON_STACK(req, tfm);
> > +       struct sg_table sgt;
> > +       struct scatterlist prealloc_sg;
> > +       char iv[AES_BLOCK_SIZE];
> > +       int pad_byte = AES_BLOCK_SIZE - (in_len & (AES_BLOCK_SIZE - 1));
> > +       int crypt_len = encrypt ? in_len + pad_byte : in_len;
> > +       int ret;
> > +
> > +       if (IS_ERR(tfm))
> > +               return PTR_ERR(tfm);
> > +
> > +       WARN_ON(crypt_len > buf_len);
> > +       if (encrypt)
> > +               memset(buf + in_len, pad_byte, pad_byte);
> > +       ret = setup_sgtable(&sgt, &prealloc_sg, buf, crypt_len);
> > +       if (ret)
> > +               goto out_tfm;
> > +
> > +       crypto_skcipher_setkey((void *)tfm, key->key, key->len);
> > +       memcpy(iv, aes_iv, AES_BLOCK_SIZE);
> > +
> > +       skcipher_request_set_tfm(req, tfm);
> > +       skcipher_request_set_callback(req, 0, NULL, NULL);
> > +       skcipher_request_set_crypt(req, sgt.sgl, sgt.sgl, crypt_len, iv);
> > +
> > +       /*
> > +       print_hex_dump(KERN_ERR, "key: ", DUMP_PREFIX_NONE, 16, 1,
> > +                      key->key, key->len, 1);
> > +       print_hex_dump(KERN_ERR, " in: ", DUMP_PREFIX_NONE, 16, 1,
> > +                      buf, crypt_len, 1);
> > +       */
> > +       if (encrypt)
> > +               ret = crypto_skcipher_encrypt(req);
> > +       else
> > +               ret = crypto_skcipher_decrypt(req);
> > +       skcipher_request_zero(req);
> > +       if (ret) {
> > +               pr_err("%s %scrypt failed: %d\n", __func__,
> > +                      encrypt ? "en" : "de", ret);
> > +               goto out_sgt;
> > +       }
> > +       /*
> > +       print_hex_dump(KERN_ERR, "out: ", DUMP_PREFIX_NONE, 16, 1,
> > +                      buf, crypt_len, 1);
> > +       */
> > +
> > +       if (encrypt) {
> > +               *pout_len = crypt_len;
> > +       } else {
> > +               pad_byte = *(char *)(buf + in_len - 1);
> > +               if (pad_byte > 0 && pad_byte <= AES_BLOCK_SIZE &&
> > +                   in_len >= pad_byte) {
> > +                       *pout_len = in_len - pad_byte;
> > +               } else {
> > +                       pr_err("%s got bad padding %d on in_len %d\n",
> > +                              __func__, pad_byte, in_len);
> > +                       ret = -EPERM;
> > +                       goto out_sgt;
> > +               }
> > +       }
> > +
> > +out_sgt:
> > +       teardown_sgtable(&sgt);
> > +out_tfm:
> > +       crypto_free_skcipher(tfm);
> > +       return ret;
> > +}
> > +
> > +int ceph_crypt(const struct ceph_crypto_key *key, bool encrypt,
> > +              void *buf, int buf_len, int in_len, int *pout_len)
> > +{
> > +       switch (key->type) {
> > +       case CEPH_CRYPTO_NONE:
> > +               *pout_len = in_len;
> > +               return 0;
> > +       case CEPH_CRYPTO_AES:
> > +               return ceph_aes_crypt(key, encrypt, buf, buf_len, in_len,
> > +                                     pout_len);
> > +       default:
> > +               return -ENOTSUPP;
> > +       }
> > +}
> > +
> >  static int ceph_key_preparse(struct key_preparsed_payload *prep)
> >  {
> >         struct ceph_crypto_key *ckey;
> > --- a/net/ceph/crypto.h
> > +++ b/net/ceph/crypto.h
> > @@ -43,6 +43,8 @@ int ceph_encrypt2(struct ceph_crypto_key
> >                   void *dst, size_t *dst_len,
> >                   const void *src1, size_t src1_len,
> >                   const void *src2, size_t src2_len);
> > +int ceph_crypt(const struct ceph_crypto_key *key, bool encrypt,
> > +              void *buf, int buf_len, int in_len, int *pout_len);
> >  int ceph_crypto_init(void);
> >  void ceph_crypto_shutdown(void);
> >
> >
> >
> > Patches currently in stable-queue which might be from idryomov@gmail.com are
> >
> > queue-4.9/libceph-introduce-ceph_crypt-for-in-place-en-decryption.patch
> 
> Hi Greg,
> 
> Taking this commit by itself without the surrounding commits
> (altogether about a dozen) doesn't make any sense.  It wasn't marked
> for stable in any way and shouldn't be included.

Ok, what were the surrounding commits?  Don't we need this to handle the
vmalloced stack issue in 4.9?  If not, that's fine, I'll drop this,
otherwise it would be good to fix that up, right?

thanks,

greg k-h