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authorIlya Dryomov <idryomov@gmail.com>2016-12-02 16:35:07 +0100
committerIlya Dryomov <idryomov@gmail.com>2016-12-12 23:09:19 +0100
commita45f795c65b479b4ba107b6ccde29b896d51ee98 (patch)
tree3dd725de40cc715dd4257db0aa73817a7fd4917b /net/ceph
parent55d9cc834f933698fc864f0d36f3cca533d30a8d (diff)
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." Signed-off-by: Ilya Dryomov <idryomov@gmail.com> Reviewed-by: Sage Weil <sage@redhat.com>
Diffstat (limited to 'net/ceph')
-rw-r--r--net/ceph/crypto.c87
-rw-r--r--net/ceph/crypto.h2
2 files changed, 89 insertions, 0 deletions
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));
+ 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;
diff --git a/net/ceph/crypto.h b/net/ceph/crypto.h
index 2e9cab09f37b..73da34e8c62e 100644
--- a/net/ceph/crypto.h
+++ b/net/ceph/crypto.h
@@ -43,6 +43,8 @@ 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);
int ceph_crypto_init(void);
void ceph_crypto_shutdown(void);