From a9f1235c8c6a89a391ab83a27969fc933041ebf1 Mon Sep 17 00:00:00 2001 From: Ilya Dryomov Date: Fri, 2 Dec 2016 16:35:07 +0100 Subject: [PATCH] libceph: introduce ceph_crypt() for in-place en/decryption 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." Change-Id: I554cae76340899bb6f00e2e06230f3a27da186a1 Signed-off-by: Ilya Dryomov Reviewed-by: Sage Weil --- 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 06f19b9e159a..7eb1b89d50a6 100644 --- a/net/ceph/crypto.c +++ b/net/ceph/crypto.c @@ -496,6 +496,93 @@ int ceph_encrypt(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)); + 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; + } +} + int ceph_encrypt2(struct ceph_crypto_key *secret, void *dst, size_t *dst_len, const void *src1, size_t src1_len, const void *src2, size_t src2_len) diff --git a/net/ceph/crypto.h b/net/ceph/crypto.h index 3572dc518bc9..8ef8ae945d7c 100644 --- a/net/ceph/crypto.h +++ b/net/ceph/crypto.h @@ -43,6 +43,8 @@ extern int ceph_encrypt2(struct ceph_crypto_key *secret, 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); extern int ceph_crypto_init(void); extern void ceph_crypto_shutdown(void);