On Mon, Dec 12, 2016 at 10:11 PM, Sage Weil <sage@xxxxxxxxxxxx> wrote:
> On Mon, 12 Dec 2016, Ilya Dryomov wrote:
>> 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@xxxxxxxxx>
>> ---
>> net/ceph/crypto.c | 87 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
>> net/ceph/crypto.h | 2 ++
>> 2 files changed, 89 insertions(+)
>>
>> diff --git a/net/ceph/crypto.c b/net/ceph/crypto.c
>> index db2847ac5f12..32099c5c4c75 100644
>> --- a/net/ceph/crypto.c
>> +++ b/net/ceph/crypto.c
>> @@ -526,6 +526,93 @@ int ceph_encrypt2(struct ceph_crypto_key *secret, void *dst, size_t *dst_len,
>> }
>> }
>>
>> +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));
>
> nit: pad_bytes?
It's also used as a PKCS7 pad *byte*
>
>> + 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);
here, so I went with byte.
Thanks,
Ilya
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