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libceph: add support for CEPH_CRYPTO_AES256KRB5

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This is based on AES256-CTS-HMAC384-192 crypto algorithm per RFC 8009
(i.e. Kerberos 5, hence the name) with custom-defined key usage numbers.
The implementation allows a given key to have/be linked to between one
and three usage numbers.

The existing CEPH_CRYPTO_AES remains in place and unchanged.  The
usage_slot parameter that needed to be added to ceph_crypt() and its
wrappers is simply ignored there.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
This commit is contained in:
Ilya Dryomov 2025-12-22 20:41:27 +01:00
parent 6cec0b61aa
commit b7cc142dba
6 changed files with 257 additions and 48 deletions
Download patch file Download diff file Expand all files Collapse all files

5
include/linux/ceph/ceph_fs.h
View file

@ -89,8 +89,9 @@ struct ceph_dir_layout {
} __attribute__ ((packed));
/* crypto algorithms */
#define CEPH_CRYPTO_NONE 0x0
#define CEPH_CRYPTO_AES 0x1
#define CEPH_CRYPTO_NONE 0x0
#define CEPH_CRYPTO_AES 0x1
#define CEPH_CRYPTO_AES256KRB5 0x2 /* AES256-CTS-HMAC384-192 */
#define CEPH_AES_IV "cephsageyudagreg"

1
net/ceph/Kconfig
View file

@ -6,6 +6,7 @@ config CEPH_LIB
select CRYPTO_AES
select CRYPTO_CBC
select CRYPTO_GCM
select CRYPTO_KRB5
select CRYPTO_LIB_SHA256
select CRYPTO
select KEYS

88
net/ceph/auth_x.c
View file

@ -17,6 +17,22 @@
#include "auth_x.h"
#include "auth_x_protocol.h"
static const u32 ticket_key_usages[] = {
CEPHX_KEY_USAGE_TICKET_SESSION_KEY,
CEPHX_KEY_USAGE_TICKET_BLOB,
CEPHX_KEY_USAGE_AUTH_CONNECTION_SECRET
};
static const u32 authorizer_key_usages[] = {
CEPHX_KEY_USAGE_AUTHORIZE,
CEPHX_KEY_USAGE_AUTHORIZE_CHALLENGE,
CEPHX_KEY_USAGE_AUTHORIZE_REPLY
};
static const u32 client_key_usages[] = {
CEPHX_KEY_USAGE_TICKET_SESSION_KEY
};
static void ceph_x_validate_tickets(struct ceph_auth_client *ac, int *pneed);
static int ceph_x_is_authenticated(struct ceph_auth_client *ac)
@ -57,6 +73,7 @@ static int ceph_x_encrypt_offset(const struct ceph_crypto_key *key)
/*
* AES: ciphertext_len | hdr | data... | padding
* AES256KRB5: ciphertext_len | confounder | hdr | data... | hmac
*/
static int ceph_x_encrypt_buflen(const struct ceph_crypto_key *key,
int data_len)
@ -65,19 +82,19 @@ static int ceph_x_encrypt_buflen(const struct ceph_crypto_key *key,
return sizeof(u32) + ceph_crypt_buflen(key, encrypt_len);
}
static int ceph_x_encrypt(struct ceph_crypto_key *secret, void *buf,
int buf_len, int plaintext_len)
static int ceph_x_encrypt(const struct ceph_crypto_key *key, int usage_slot,
void *buf, int buf_len, int plaintext_len)
{
struct ceph_x_encrypt_header *hdr;
int ciphertext_len;
int ret;
hdr = buf + sizeof(u32) + ceph_crypt_data_offset(secret);
hdr = buf + sizeof(u32) + ceph_crypt_data_offset(key);
hdr->struct_v = 1;
hdr->magic = cpu_to_le64(CEPHX_ENC_MAGIC);
ret = ceph_crypt(secret, true, buf + sizeof(u32), buf_len - sizeof(u32),
plaintext_len + sizeof(struct ceph_x_encrypt_header),
ret = ceph_crypt(key, usage_slot, true, buf + sizeof(u32),
buf_len - sizeof(u32), plaintext_len + sizeof(*hdr),
&ciphertext_len);
if (ret)
return ret;
@ -86,19 +103,19 @@ static int ceph_x_encrypt(struct ceph_crypto_key *secret, void *buf,
return sizeof(u32) + ciphertext_len;
}
static int __ceph_x_decrypt(struct ceph_crypto_key *secret, void *p,
int ciphertext_len)
static int __ceph_x_decrypt(const struct ceph_crypto_key *key, int usage_slot,
void *p, int ciphertext_len)
{
struct ceph_x_encrypt_header *hdr;
int plaintext_len;
int ret;
ret = ceph_crypt(secret, false, p, ciphertext_len, ciphertext_len,
&plaintext_len);
ret = ceph_crypt(key, usage_slot, false, p, ciphertext_len,
ciphertext_len, &plaintext_len);
if (ret)
return ret;
hdr = p + ceph_crypt_data_offset(secret);
hdr = p + ceph_crypt_data_offset(key);
if (le64_to_cpu(hdr->magic) != CEPHX_ENC_MAGIC) {
pr_err("%s bad magic\n", __func__);
return -EINVAL;
@ -107,7 +124,8 @@ static int __ceph_x_decrypt(struct ceph_crypto_key *secret, void *p,
return plaintext_len - sizeof(*hdr);
}
static int ceph_x_decrypt(struct ceph_crypto_key *secret, void **p, void *end)
static int ceph_x_decrypt(const struct ceph_crypto_key *key, int usage_slot,
void **p, void *end)
{
int ciphertext_len;
int ret;
@ -115,7 +133,7 @@ static int ceph_x_decrypt(struct ceph_crypto_key *secret, void **p, void *end)
ceph_decode_32_safe(p, end, ciphertext_len, e_inval);
ceph_decode_need(p, end, ciphertext_len, e_inval);
ret = __ceph_x_decrypt(secret, *p, ciphertext_len);
ret = __ceph_x_decrypt(key, usage_slot, *p, ciphertext_len);
if (ret < 0)
return ret;
@ -207,7 +225,9 @@ static int process_one_ticket(struct ceph_auth_client *ac,
/* blob for me */
dp = *p + ceph_x_encrypt_offset(secret);
ret = ceph_x_decrypt(secret, p, end);
ret = ceph_x_decrypt(secret,
0 /* CEPHX_KEY_USAGE_TICKET_SESSION_KEY */,
p, end);
if (ret < 0)
goto out;
dout(" decrypted %d bytes\n", ret);
@ -221,7 +241,8 @@ static int process_one_ticket(struct ceph_auth_client *ac,
if (ret)
goto out;
ret = ceph_crypto_key_prepare(&new_session_key);
ret = ceph_crypto_key_prepare(&new_session_key, ticket_key_usages,
ARRAY_SIZE(ticket_key_usages));
if (ret)
goto out;
@ -238,7 +259,9 @@ static int process_one_ticket(struct ceph_auth_client *ac,
if (is_enc) {
/* encrypted */
tp = *p + ceph_x_encrypt_offset(&th->session_key);
ret = ceph_x_decrypt(&th->session_key, p, end);
ret = ceph_x_decrypt(&th->session_key,
1 /* CEPHX_KEY_USAGE_TICKET_BLOB */,
p, end);
if (ret < 0)
goto out;
dout(" encrypted ticket, decrypted %d bytes\n", ret);
@ -341,7 +364,9 @@ static int encrypt_authorizer(struct ceph_x_authorizer *au,
msg_b->server_challenge_plus_one = 0;
}
ret = ceph_x_encrypt(&au->session_key, p, end - p, sizeof(*msg_b));
ret = ceph_x_encrypt(&au->session_key,
0 /* CEPHX_KEY_USAGE_AUTHORIZE */,
p, end - p, sizeof(*msg_b));
if (ret < 0)
return ret;
@ -384,7 +409,8 @@ static int ceph_x_build_authorizer(struct ceph_auth_client *ac,
if (ret)
goto out_au;
ret = ceph_crypto_key_prepare(&au->session_key);
ret = ceph_crypto_key_prepare(&au->session_key, authorizer_key_usages,
ARRAY_SIZE(authorizer_key_usages));
if (ret)
goto out_au;
@ -542,7 +568,8 @@ static int ceph_x_build_request(struct ceph_auth_client *ac,
get_random_bytes(&auth->client_challenge, sizeof(u64));
blob->client_challenge = auth->client_challenge;
blob->server_challenge = cpu_to_le64(xi->server_challenge);
ret = ceph_x_encrypt(&xi->secret, enc_buf, CEPHX_AU_ENC_BUF_LEN,
ret = ceph_x_encrypt(&xi->secret, 0 /* dummy */,
enc_buf, CEPHX_AU_ENC_BUF_LEN,
sizeof(*blob));
if (ret < 0)
return ret;
@ -656,7 +683,9 @@ static int handle_auth_session_key(struct ceph_auth_client *ac, u64 global_id,
dout("%s connection secret blob len %d\n", __func__, len);
if (len > 0) {
dp = *p + ceph_x_encrypt_offset(&th->session_key);
ret = ceph_x_decrypt(&th->session_key, p, *p + len);
ret = ceph_x_decrypt(&th->session_key,
2 /* CEPHX_KEY_USAGE_AUTH_CONNECTION_SECRET */,
p, *p + len);
if (ret < 0)
return ret;
@ -820,7 +849,9 @@ static int decrypt_authorizer_challenge(struct ceph_crypto_key *secret,
int ret;
/* no leading len */
ret = __ceph_x_decrypt(secret, challenge, challenge_len);
ret = __ceph_x_decrypt(secret,
1 /* CEPHX_KEY_USAGE_AUTHORIZE_CHALLENGE */,
challenge, challenge_len);
if (ret < 0)
return ret;
@ -873,7 +904,8 @@ static int decrypt_authorizer_reply(struct ceph_crypto_key *secret,
int ret;
dp = *p + ceph_x_encrypt_offset(secret);
ret = ceph_x_decrypt(secret, p, end);
ret = ceph_x_decrypt(secret, 2 /* CEPHX_KEY_USAGE_AUTHORIZE_REPLY */,
p, end);
if (ret < 0)
return ret;
@ -1004,8 +1036,9 @@ static int calc_signature(struct ceph_x_authorizer *au, struct ceph_msg *msg,
sigblock->middle_crc = msg->footer.middle_crc;
sigblock->data_crc = msg->footer.data_crc;
ret = ceph_x_encrypt(&au->session_key, enc_buf,
CEPHX_AU_ENC_BUF_LEN, sizeof(*sigblock));
ret = ceph_x_encrypt(&au->session_key, 0 /* dummy */,
enc_buf, CEPHX_AU_ENC_BUF_LEN,
sizeof(*sigblock));
if (ret < 0)
return ret;
@ -1036,9 +1069,9 @@ static int calc_signature(struct ceph_x_authorizer *au, struct ceph_msg *msg,
sigblock->seq_lower_word = *(__le32 *)&msg->hdr.seq;
/* no leading len, no ceph_x_encrypt_header */
ret = ceph_crypt(&au->session_key, true, enc_buf,
CEPHX_AU_ENC_BUF_LEN, sizeof(*sigblock),
&ciphertext_len);
ret = ceph_crypt(&au->session_key, 0 /* dummy */,
true, enc_buf, CEPHX_AU_ENC_BUF_LEN,
sizeof(*sigblock), &ciphertext_len);
if (ret)
return ret;
@ -1130,7 +1163,8 @@ int ceph_x_init(struct ceph_auth_client *ac)
goto err_xi;
}
ret = ceph_crypto_key_prepare(&xi->secret);
ret = ceph_crypto_key_prepare(&xi->secret, client_key_usages,
ARRAY_SIZE(client_key_usages));
if (ret) {
pr_err("cannot prepare key: %d\n", ret);
goto err_secret;

38
net/ceph/auth_x_protocol.h
View file

@ -6,6 +6,44 @@
#define CEPHX_GET_PRINCIPAL_SESSION_KEY 0x0200
#define CEPHX_GET_ROTATING_KEY 0x0400
/* Client <-> AuthMonitor */
/*
* The AUTH session's connection secret: encrypted with the AUTH
* ticket session key
*/
#define CEPHX_KEY_USAGE_AUTH_CONNECTION_SECRET 0x03
/*
* The ticket's blob for the client ("blob for me", contains the
* session key): encrypted with the client's secret key in case of
* the AUTH ticket and the AUTH ticket session key in case of other
* service tickets
*/
#define CEPHX_KEY_USAGE_TICKET_SESSION_KEY 0x04
/*
* The ticket's blob for the service (ceph_x_ticket_blob): possibly
* encrypted with the old AUTH ticket session key in case of the AUTH
* ticket and not encrypted in case of other service tickets
*/
#define CEPHX_KEY_USAGE_TICKET_BLOB 0x05
/* Client <-> Service */
/*
* The client's authorization request (ceph_x_authorize_b):
* encrypted with the service ticket session key
*/
#define CEPHX_KEY_USAGE_AUTHORIZE 0x10
/*
* The service's challenge (ceph_x_authorize_challenge):
* encrypted with the service ticket session key
*/
#define CEPHX_KEY_USAGE_AUTHORIZE_CHALLENGE 0x11
/*
* The service's final reply (ceph_x_authorize_reply + the service
* session's connection secret): encrypted with the service ticket
* session key
*/
#define CEPHX_KEY_USAGE_AUTHORIZE_REPLY 0x12
/* common bits */
struct ceph_x_ticket_blob {
__u8 struct_v;

157
net/ceph/crypto.c
View file

@ -7,6 +7,7 @@
#include <linux/sched.h>
#include <linux/slab.h>
#include <crypto/aes.h>
#include <crypto/krb5.h>
#include <crypto/skcipher.h>
#include <linux/key-type.h>
#include <linux/sched/mm.h>
@ -22,28 +23,68 @@ static int set_aes_tfm(struct ceph_crypto_key *key)
int ret;
noio_flag = memalloc_noio_save();
key->tfm = crypto_alloc_sync_skcipher("cbc(aes)", 0, 0);
key->aes_tfm = crypto_alloc_sync_skcipher("cbc(aes)", 0, 0);
memalloc_noio_restore(noio_flag);
if (IS_ERR(key->tfm)) {
ret = PTR_ERR(key->tfm);
key->tfm = NULL;
if (IS_ERR(key->aes_tfm)) {
ret = PTR_ERR(key->aes_tfm);
key->aes_tfm = NULL;
return ret;
}
ret = crypto_sync_skcipher_setkey(key->tfm, key->key, key->len);
ret = crypto_sync_skcipher_setkey(key->aes_tfm, key->key, key->len);
if (ret)
return ret;
return 0;
}
int ceph_crypto_key_prepare(struct ceph_crypto_key *key)
static int set_krb5_tfms(struct ceph_crypto_key *key, const u32 *key_usages,
int key_usage_cnt)
{
struct krb5_buffer TK = { .len = key->len, .data = key->key };
unsigned int noio_flag;
int ret = 0;
int i;
if (WARN_ON_ONCE(key_usage_cnt > ARRAY_SIZE(key->krb5_tfms)))
return -EINVAL;
key->krb5_type = crypto_krb5_find_enctype(
KRB5_ENCTYPE_AES256_CTS_HMAC_SHA384_192);
if (!key->krb5_type)
return -ENOPKG;
/*
* Despite crypto_krb5_prepare_encryption() taking a gfp mask,
* crypto_alloc_aead() inside of it allocates with GFP_KERNEL.
*/
noio_flag = memalloc_noio_save();
for (i = 0; i < key_usage_cnt; i++) {
key->krb5_tfms[i] = crypto_krb5_prepare_encryption(
key->krb5_type, &TK, key_usages[i],
GFP_NOIO);
if (IS_ERR(key->krb5_tfms[i])) {
ret = PTR_ERR(key->krb5_tfms[i]);
key->krb5_tfms[i] = NULL;
goto out_flag;
}
}
out_flag:
memalloc_noio_restore(noio_flag);
return ret;
}
int ceph_crypto_key_prepare(struct ceph_crypto_key *key,
const u32 *key_usages, int key_usage_cnt)
{
switch (key->type) {
case CEPH_CRYPTO_NONE:
return 0; /* nothing to do */
case CEPH_CRYPTO_AES:
return set_aes_tfm(key);
case CEPH_CRYPTO_AES256KRB5:
return set_krb5_tfms(key, key_usages, key_usage_cnt);
default:
return -ENOTSUPP;
}
@ -123,12 +164,25 @@ int ceph_crypto_key_unarmor(struct ceph_crypto_key *key, const char *inkey)
void ceph_crypto_key_destroy(struct ceph_crypto_key *key)
{
if (key) {
kfree_sensitive(key->key);
key->key = NULL;
if (key->tfm) {
crypto_free_sync_skcipher(key->tfm);
key->tfm = NULL;
int i;
if (!key)
return;
kfree_sensitive(key->key);
key->key = NULL;
if (key->type == CEPH_CRYPTO_AES) {
if (key->aes_tfm) {
crypto_free_sync_skcipher(key->aes_tfm);
key->aes_tfm = NULL;
}
} else if (key->type == CEPH_CRYPTO_AES256KRB5) {
for (i = 0; i < ARRAY_SIZE(key->krb5_tfms); i++) {
if (key->krb5_tfms[i]) {
crypto_free_aead(key->krb5_tfms[i]);
key->krb5_tfms[i] = NULL;
}
}
}
}
@ -208,7 +262,7 @@ static void teardown_sgtable(struct sg_table *sgt)
static int ceph_aes_crypt(const struct ceph_crypto_key *key, bool encrypt,
void *buf, int buf_len, int in_len, int *pout_len)
{
SYNC_SKCIPHER_REQUEST_ON_STACK(req, key->tfm);
SYNC_SKCIPHER_REQUEST_ON_STACK(req, key->aes_tfm);
struct sg_table sgt;
struct scatterlist prealloc_sg;
char iv[AES_BLOCK_SIZE] __aligned(8);
@ -224,7 +278,7 @@ static int ceph_aes_crypt(const struct ceph_crypto_key *key, bool encrypt,
return ret;
memcpy(iv, aes_iv, AES_BLOCK_SIZE);
skcipher_request_set_sync_tfm(req, key->tfm);
skcipher_request_set_sync_tfm(req, key->aes_tfm);
skcipher_request_set_callback(req, 0, NULL, NULL);
skcipher_request_set_crypt(req, sgt.sgl, sgt.sgl, crypt_len, iv);
@ -269,7 +323,68 @@ out_sgt:
return ret;
}
int ceph_crypt(const struct ceph_crypto_key *key, bool encrypt,
static int ceph_krb5_encrypt(const struct ceph_crypto_key *key, int usage_slot,
void *buf, int buf_len, int in_len, int *pout_len)
{
struct sg_table sgt;
struct scatterlist prealloc_sg;
int ret;
if (WARN_ON_ONCE(usage_slot >= ARRAY_SIZE(key->krb5_tfms)))
return -EINVAL;
ret = setup_sgtable(&sgt, &prealloc_sg, buf, buf_len);
if (ret)
return ret;
ret = crypto_krb5_encrypt(key->krb5_type, key->krb5_tfms[usage_slot],
sgt.sgl, sgt.nents, buf_len, AES_BLOCK_SIZE,
in_len, false);
if (ret < 0) {
pr_err("%s encrypt failed: %d\n", __func__, ret);
goto out_sgt;
}
*pout_len = ret;
ret = 0;
out_sgt:
teardown_sgtable(&sgt);
return ret;
}
static int ceph_krb5_decrypt(const struct ceph_crypto_key *key, int usage_slot,
void *buf, int buf_len, int in_len, int *pout_len)
{
struct sg_table sgt;
struct scatterlist prealloc_sg;
size_t data_off = 0;
size_t data_len = in_len;
int ret;
if (WARN_ON_ONCE(usage_slot >= ARRAY_SIZE(key->krb5_tfms)))
return -EINVAL;
ret = setup_sgtable(&sgt, &prealloc_sg, buf, in_len);
if (ret)
return ret;
ret = crypto_krb5_decrypt(key->krb5_type, key->krb5_tfms[usage_slot],
sgt.sgl, sgt.nents, &data_off, &data_len);
if (ret) {
pr_err("%s decrypt failed: %d\n", __func__, ret);
goto out_sgt;
}
WARN_ON(data_off != AES_BLOCK_SIZE);
*pout_len = data_len;
out_sgt:
teardown_sgtable(&sgt);
return ret;
}
int ceph_crypt(const struct ceph_crypto_key *key, int usage_slot, bool encrypt,
void *buf, int buf_len, int in_len, int *pout_len)
{
switch (key->type) {
@ -279,6 +394,12 @@ int ceph_crypt(const struct ceph_crypto_key *key, bool encrypt,
case CEPH_CRYPTO_AES:
return ceph_aes_crypt(key, encrypt, buf, buf_len, in_len,
pout_len);
case CEPH_CRYPTO_AES256KRB5:
return encrypt ?
ceph_krb5_encrypt(key, usage_slot, buf, buf_len, in_len,
pout_len) :
ceph_krb5_decrypt(key, usage_slot, buf, buf_len, in_len,
pout_len);
default:
return -ENOTSUPP;
}
@ -290,6 +411,9 @@ int ceph_crypt_data_offset(const struct ceph_crypto_key *key)
case CEPH_CRYPTO_NONE:
case CEPH_CRYPTO_AES:
return 0;
case CEPH_CRYPTO_AES256KRB5:
/* confounder */
return AES_BLOCK_SIZE;
default:
BUG();
}
@ -304,6 +428,9 @@ int ceph_crypt_buflen(const struct ceph_crypto_key *key, int data_len)
/* PKCS#7 padding at the end */
return data_len + AES_BLOCK_SIZE -
(data_len & (AES_BLOCK_SIZE - 1));
case CEPH_CRYPTO_AES256KRB5:
/* confounder at the beginning and 192-bit HMAC at the end */
return AES_BLOCK_SIZE + data_len + 24;
default:
BUG();
}

16
net/ceph/crypto.h
View file

@ -5,7 +5,7 @@
#include <linux/ceph/types.h>
#include <linux/ceph/buffer.h>
#define CEPH_MAX_KEY_LEN 16
#define CEPH_MAX_KEY_LEN 32
#define CEPH_MAX_CON_SECRET_LEN 64
/*
@ -16,10 +16,18 @@ struct ceph_crypto_key {
struct ceph_timespec created;
int len;
void *key;
struct crypto_sync_skcipher *tfm;
union {
struct crypto_sync_skcipher *aes_tfm;
struct {
const struct krb5_enctype *krb5_type;
struct crypto_aead *krb5_tfms[3];
};
};
};
int ceph_crypto_key_prepare(struct ceph_crypto_key *key);
int ceph_crypto_key_prepare(struct ceph_crypto_key *key,
const u32 *key_usages, int key_usage_cnt);
int ceph_crypto_key_clone(struct ceph_crypto_key *dst,
const struct ceph_crypto_key *src);
int ceph_crypto_key_decode(struct ceph_crypto_key *key, void **p, void *end);
@ -27,7 +35,7 @@ int ceph_crypto_key_unarmor(struct ceph_crypto_key *key, const char *in);
void ceph_crypto_key_destroy(struct ceph_crypto_key *key);
/* crypto.c */
int ceph_crypt(const struct ceph_crypto_key *key, bool encrypt,
int ceph_crypt(const struct ceph_crypto_key *key, int usage_slot, bool encrypt,
void *buf, int buf_len, int in_len, int *pout_len);
int ceph_crypt_data_offset(const struct ceph_crypto_key *key);
int ceph_crypt_buflen(const struct ceph_crypto_key *key, int data_len);