WSL2-Linux-Kernel/net/ceph/auth_x.c

826 строки
20 KiB
C

// SPDX-License-Identifier: GPL-2.0
#include <linux/ceph/ceph_debug.h>
#include <linux/err.h>
#include <linux/module.h>
#include <linux/random.h>
#include <linux/slab.h>
#include <linux/ceph/decode.h>
#include <linux/ceph/auth.h>
#include <linux/ceph/libceph.h>
#include <linux/ceph/messenger.h>
#include "crypto.h"
#include "auth_x.h"
#include "auth_x_protocol.h"
static void ceph_x_validate_tickets(struct ceph_auth_client *ac, int *pneed);
static int ceph_x_is_authenticated(struct ceph_auth_client *ac)
{
struct ceph_x_info *xi = ac->private;
int need;
ceph_x_validate_tickets(ac, &need);
dout("ceph_x_is_authenticated want=%d need=%d have=%d\n",
ac->want_keys, need, xi->have_keys);
return (ac->want_keys & xi->have_keys) == ac->want_keys;
}
static int ceph_x_should_authenticate(struct ceph_auth_client *ac)
{
struct ceph_x_info *xi = ac->private;
int need;
ceph_x_validate_tickets(ac, &need);
dout("ceph_x_should_authenticate want=%d need=%d have=%d\n",
ac->want_keys, need, xi->have_keys);
return need != 0;
}
static int ceph_x_encrypt_offset(void)
{
return sizeof(u32) + sizeof(struct ceph_x_encrypt_header);
}
static int ceph_x_encrypt_buflen(int ilen)
{
return ceph_x_encrypt_offset() + ilen + 16;
}
static int ceph_x_encrypt(struct ceph_crypto_key *secret, void *buf,
int buf_len, int plaintext_len)
{
struct ceph_x_encrypt_header *hdr = buf + sizeof(u32);
int ciphertext_len;
int ret;
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),
&ciphertext_len);
if (ret)
return ret;
ceph_encode_32(&buf, ciphertext_len);
return sizeof(u32) + ciphertext_len;
}
static int ceph_x_decrypt(struct ceph_crypto_key *secret, void **p, void *end)
{
struct ceph_x_encrypt_header *hdr = *p + sizeof(u32);
int ciphertext_len, plaintext_len;
int ret;
ceph_decode_32_safe(p, end, ciphertext_len, e_inval);
ceph_decode_need(p, end, ciphertext_len, e_inval);
ret = ceph_crypt(secret, false, *p, end - *p, ciphertext_len,
&plaintext_len);
if (ret)
return ret;
if (hdr->struct_v != 1 || le64_to_cpu(hdr->magic) != CEPHX_ENC_MAGIC)
return -EPERM;
*p += ciphertext_len;
return plaintext_len - sizeof(struct ceph_x_encrypt_header);
e_inval:
return -EINVAL;
}
/*
* get existing (or insert new) ticket handler
*/
static struct ceph_x_ticket_handler *
get_ticket_handler(struct ceph_auth_client *ac, int service)
{
struct ceph_x_ticket_handler *th;
struct ceph_x_info *xi = ac->private;
struct rb_node *parent = NULL, **p = &xi->ticket_handlers.rb_node;
while (*p) {
parent = *p;
th = rb_entry(parent, struct ceph_x_ticket_handler, node);
if (service < th->service)
p = &(*p)->rb_left;
else if (service > th->service)
p = &(*p)->rb_right;
else
return th;
}
/* add it */
th = kzalloc(sizeof(*th), GFP_NOFS);
if (!th)
return ERR_PTR(-ENOMEM);
th->service = service;
rb_link_node(&th->node, parent, p);
rb_insert_color(&th->node, &xi->ticket_handlers);
return th;
}
static void remove_ticket_handler(struct ceph_auth_client *ac,
struct ceph_x_ticket_handler *th)
{
struct ceph_x_info *xi = ac->private;
dout("remove_ticket_handler %p %d\n", th, th->service);
rb_erase(&th->node, &xi->ticket_handlers);
ceph_crypto_key_destroy(&th->session_key);
if (th->ticket_blob)
ceph_buffer_put(th->ticket_blob);
kfree(th);
}
static int process_one_ticket(struct ceph_auth_client *ac,
struct ceph_crypto_key *secret,
void **p, void *end)
{
struct ceph_x_info *xi = ac->private;
int type;
u8 tkt_struct_v, blob_struct_v;
struct ceph_x_ticket_handler *th;
void *dp, *dend;
int dlen;
char is_enc;
struct timespec64 validity;
void *tp, *tpend;
void **ptp;
struct ceph_crypto_key new_session_key = { 0 };
struct ceph_buffer *new_ticket_blob;
time64_t new_expires, new_renew_after;
u64 new_secret_id;
int ret;
ceph_decode_need(p, end, sizeof(u32) + 1, bad);
type = ceph_decode_32(p);
dout(" ticket type %d %s\n", type, ceph_entity_type_name(type));
tkt_struct_v = ceph_decode_8(p);
if (tkt_struct_v != 1)
goto bad;
th = get_ticket_handler(ac, type);
if (IS_ERR(th)) {
ret = PTR_ERR(th);
goto out;
}
/* blob for me */
dp = *p + ceph_x_encrypt_offset();
ret = ceph_x_decrypt(secret, p, end);
if (ret < 0)
goto out;
dout(" decrypted %d bytes\n", ret);
dend = dp + ret;
tkt_struct_v = ceph_decode_8(&dp);
if (tkt_struct_v != 1)
goto bad;
ret = ceph_crypto_key_decode(&new_session_key, &dp, dend);
if (ret)
goto out;
ceph_decode_timespec64(&validity, dp);
dp += sizeof(struct ceph_timespec);
new_expires = ktime_get_real_seconds() + validity.tv_sec;
new_renew_after = new_expires - (validity.tv_sec / 4);
dout(" expires=%llu renew_after=%llu\n", new_expires,
new_renew_after);
/* ticket blob for service */
ceph_decode_8_safe(p, end, is_enc, bad);
if (is_enc) {
/* encrypted */
tp = *p + ceph_x_encrypt_offset();
ret = ceph_x_decrypt(&th->session_key, p, end);
if (ret < 0)
goto out;
dout(" encrypted ticket, decrypted %d bytes\n", ret);
ptp = &tp;
tpend = tp + ret;
} else {
/* unencrypted */
ptp = p;
tpend = end;
}
ceph_decode_32_safe(ptp, tpend, dlen, bad);
dout(" ticket blob is %d bytes\n", dlen);
ceph_decode_need(ptp, tpend, 1 + sizeof(u64), bad);
blob_struct_v = ceph_decode_8(ptp);
if (blob_struct_v != 1)
goto bad;
new_secret_id = ceph_decode_64(ptp);
ret = ceph_decode_buffer(&new_ticket_blob, ptp, tpend);
if (ret)
goto out;
/* all is well, update our ticket */
ceph_crypto_key_destroy(&th->session_key);
if (th->ticket_blob)
ceph_buffer_put(th->ticket_blob);
th->session_key = new_session_key;
th->ticket_blob = new_ticket_blob;
th->secret_id = new_secret_id;
th->expires = new_expires;
th->renew_after = new_renew_after;
th->have_key = true;
dout(" got ticket service %d (%s) secret_id %lld len %d\n",
type, ceph_entity_type_name(type), th->secret_id,
(int)th->ticket_blob->vec.iov_len);
xi->have_keys |= th->service;
return 0;
bad:
ret = -EINVAL;
out:
ceph_crypto_key_destroy(&new_session_key);
return ret;
}
static int ceph_x_proc_ticket_reply(struct ceph_auth_client *ac,
struct ceph_crypto_key *secret,
void *buf, void *end)
{
void *p = buf;
u8 reply_struct_v;
u32 num;
int ret;
ceph_decode_8_safe(&p, end, reply_struct_v, bad);
if (reply_struct_v != 1)
return -EINVAL;
ceph_decode_32_safe(&p, end, num, bad);
dout("%d tickets\n", num);
while (num--) {
ret = process_one_ticket(ac, secret, &p, end);
if (ret)
return ret;
}
return 0;
bad:
return -EINVAL;
}
static void ceph_x_authorizer_cleanup(struct ceph_x_authorizer *au)
{
ceph_crypto_key_destroy(&au->session_key);
if (au->buf) {
ceph_buffer_put(au->buf);
au->buf = NULL;
}
}
static int ceph_x_build_authorizer(struct ceph_auth_client *ac,
struct ceph_x_ticket_handler *th,
struct ceph_x_authorizer *au)
{
int maxlen;
struct ceph_x_authorize_a *msg_a;
struct ceph_x_authorize_b *msg_b;
void *p, *end;
int ret;
int ticket_blob_len =
(th->ticket_blob ? th->ticket_blob->vec.iov_len : 0);
dout("build_authorizer for %s %p\n",
ceph_entity_type_name(th->service), au);
ceph_crypto_key_destroy(&au->session_key);
ret = ceph_crypto_key_clone(&au->session_key, &th->session_key);
if (ret)
goto out_au;
maxlen = sizeof(*msg_a) + ticket_blob_len +
ceph_x_encrypt_buflen(sizeof(*msg_b));
dout(" need len %d\n", maxlen);
if (au->buf && au->buf->alloc_len < maxlen) {
ceph_buffer_put(au->buf);
au->buf = NULL;
}
if (!au->buf) {
au->buf = ceph_buffer_new(maxlen, GFP_NOFS);
if (!au->buf) {
ret = -ENOMEM;
goto out_au;
}
}
au->service = th->service;
au->secret_id = th->secret_id;
msg_a = au->buf->vec.iov_base;
msg_a->struct_v = 1;
msg_a->global_id = cpu_to_le64(ac->global_id);
msg_a->service_id = cpu_to_le32(th->service);
msg_a->ticket_blob.struct_v = 1;
msg_a->ticket_blob.secret_id = cpu_to_le64(th->secret_id);
msg_a->ticket_blob.blob_len = cpu_to_le32(ticket_blob_len);
if (ticket_blob_len) {
memcpy(msg_a->ticket_blob.blob, th->ticket_blob->vec.iov_base,
th->ticket_blob->vec.iov_len);
}
dout(" th %p secret_id %lld %lld\n", th, th->secret_id,
le64_to_cpu(msg_a->ticket_blob.secret_id));
p = msg_a + 1;
p += ticket_blob_len;
end = au->buf->vec.iov_base + au->buf->vec.iov_len;
msg_b = p + ceph_x_encrypt_offset();
msg_b->struct_v = 1;
get_random_bytes(&au->nonce, sizeof(au->nonce));
msg_b->nonce = cpu_to_le64(au->nonce);
ret = ceph_x_encrypt(&au->session_key, p, end - p, sizeof(*msg_b));
if (ret < 0)
goto out_au;
p += ret;
WARN_ON(p > end);
au->buf->vec.iov_len = p - au->buf->vec.iov_base;
dout(" built authorizer nonce %llx len %d\n", au->nonce,
(int)au->buf->vec.iov_len);
return 0;
out_au:
ceph_x_authorizer_cleanup(au);
return ret;
}
static int ceph_x_encode_ticket(struct ceph_x_ticket_handler *th,
void **p, void *end)
{
ceph_decode_need(p, end, 1 + sizeof(u64), bad);
ceph_encode_8(p, 1);
ceph_encode_64(p, th->secret_id);
if (th->ticket_blob) {
const char *buf = th->ticket_blob->vec.iov_base;
u32 len = th->ticket_blob->vec.iov_len;
ceph_encode_32_safe(p, end, len, bad);
ceph_encode_copy_safe(p, end, buf, len, bad);
} else {
ceph_encode_32_safe(p, end, 0, bad);
}
return 0;
bad:
return -ERANGE;
}
static bool need_key(struct ceph_x_ticket_handler *th)
{
if (!th->have_key)
return true;
return ktime_get_real_seconds() >= th->renew_after;
}
static bool have_key(struct ceph_x_ticket_handler *th)
{
if (th->have_key) {
if (ktime_get_real_seconds() >= th->expires)
th->have_key = false;
}
return th->have_key;
}
static void ceph_x_validate_tickets(struct ceph_auth_client *ac, int *pneed)
{
int want = ac->want_keys;
struct ceph_x_info *xi = ac->private;
int service;
*pneed = ac->want_keys & ~(xi->have_keys);
for (service = 1; service <= want; service <<= 1) {
struct ceph_x_ticket_handler *th;
if (!(ac->want_keys & service))
continue;
if (*pneed & service)
continue;
th = get_ticket_handler(ac, service);
if (IS_ERR(th)) {
*pneed |= service;
continue;
}
if (need_key(th))
*pneed |= service;
if (!have_key(th))
xi->have_keys &= ~service;
}
}
static int ceph_x_build_request(struct ceph_auth_client *ac,
void *buf, void *end)
{
struct ceph_x_info *xi = ac->private;
int need;
struct ceph_x_request_header *head = buf;
int ret;
struct ceph_x_ticket_handler *th =
get_ticket_handler(ac, CEPH_ENTITY_TYPE_AUTH);
if (IS_ERR(th))
return PTR_ERR(th);
ceph_x_validate_tickets(ac, &need);
dout("build_request want %x have %x need %x\n",
ac->want_keys, xi->have_keys, need);
if (need & CEPH_ENTITY_TYPE_AUTH) {
struct ceph_x_authenticate *auth = (void *)(head + 1);
void *p = auth + 1;
void *enc_buf = xi->auth_authorizer.enc_buf;
struct ceph_x_challenge_blob *blob = enc_buf +
ceph_x_encrypt_offset();
u64 *u;
if (p > end)
return -ERANGE;
dout(" get_auth_session_key\n");
head->op = cpu_to_le16(CEPHX_GET_AUTH_SESSION_KEY);
/* encrypt and hash */
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,
sizeof(*blob));
if (ret < 0)
return ret;
auth->struct_v = 1;
auth->key = 0;
for (u = (u64 *)enc_buf; u + 1 <= (u64 *)(enc_buf + ret); u++)
auth->key ^= *(__le64 *)u;
dout(" server_challenge %llx client_challenge %llx key %llx\n",
xi->server_challenge, le64_to_cpu(auth->client_challenge),
le64_to_cpu(auth->key));
/* now encode the old ticket if exists */
ret = ceph_x_encode_ticket(th, &p, end);
if (ret < 0)
return ret;
return p - buf;
}
if (need) {
void *p = head + 1;
struct ceph_x_service_ticket_request *req;
if (p > end)
return -ERANGE;
head->op = cpu_to_le16(CEPHX_GET_PRINCIPAL_SESSION_KEY);
ret = ceph_x_build_authorizer(ac, th, &xi->auth_authorizer);
if (ret)
return ret;
ceph_encode_copy(&p, xi->auth_authorizer.buf->vec.iov_base,
xi->auth_authorizer.buf->vec.iov_len);
req = p;
req->keys = cpu_to_le32(need);
p += sizeof(*req);
return p - buf;
}
return 0;
}
static int ceph_x_handle_reply(struct ceph_auth_client *ac, int result,
void *buf, void *end)
{
struct ceph_x_info *xi = ac->private;
struct ceph_x_reply_header *head = buf;
struct ceph_x_ticket_handler *th;
int len = end - buf;
int op;
int ret;
if (result)
return result; /* XXX hmm? */
if (xi->starting) {
/* it's a hello */
struct ceph_x_server_challenge *sc = buf;
if (len != sizeof(*sc))
return -EINVAL;
xi->server_challenge = le64_to_cpu(sc->server_challenge);
dout("handle_reply got server challenge %llx\n",
xi->server_challenge);
xi->starting = false;
xi->have_keys &= ~CEPH_ENTITY_TYPE_AUTH;
return -EAGAIN;
}
op = le16_to_cpu(head->op);
result = le32_to_cpu(head->result);
dout("handle_reply op %d result %d\n", op, result);
switch (op) {
case CEPHX_GET_AUTH_SESSION_KEY:
/* verify auth key */
ret = ceph_x_proc_ticket_reply(ac, &xi->secret,
buf + sizeof(*head), end);
break;
case CEPHX_GET_PRINCIPAL_SESSION_KEY:
th = get_ticket_handler(ac, CEPH_ENTITY_TYPE_AUTH);
if (IS_ERR(th))
return PTR_ERR(th);
ret = ceph_x_proc_ticket_reply(ac, &th->session_key,
buf + sizeof(*head), end);
break;
default:
return -EINVAL;
}
if (ret)
return ret;
if (ac->want_keys == xi->have_keys)
return 0;
return -EAGAIN;
}
static void ceph_x_destroy_authorizer(struct ceph_authorizer *a)
{
struct ceph_x_authorizer *au = (void *)a;
ceph_x_authorizer_cleanup(au);
kfree(au);
}
static int ceph_x_create_authorizer(
struct ceph_auth_client *ac, int peer_type,
struct ceph_auth_handshake *auth)
{
struct ceph_x_authorizer *au;
struct ceph_x_ticket_handler *th;
int ret;
th = get_ticket_handler(ac, peer_type);
if (IS_ERR(th))
return PTR_ERR(th);
au = kzalloc(sizeof(*au), GFP_NOFS);
if (!au)
return -ENOMEM;
au->base.destroy = ceph_x_destroy_authorizer;
ret = ceph_x_build_authorizer(ac, th, au);
if (ret) {
kfree(au);
return ret;
}
auth->authorizer = (struct ceph_authorizer *) au;
auth->authorizer_buf = au->buf->vec.iov_base;
auth->authorizer_buf_len = au->buf->vec.iov_len;
auth->authorizer_reply_buf = au->enc_buf;
auth->authorizer_reply_buf_len = CEPHX_AU_ENC_BUF_LEN;
auth->sign_message = ac->ops->sign_message;
auth->check_message_signature = ac->ops->check_message_signature;
return 0;
}
static int ceph_x_update_authorizer(
struct ceph_auth_client *ac, int peer_type,
struct ceph_auth_handshake *auth)
{
struct ceph_x_authorizer *au;
struct ceph_x_ticket_handler *th;
th = get_ticket_handler(ac, peer_type);
if (IS_ERR(th))
return PTR_ERR(th);
au = (struct ceph_x_authorizer *)auth->authorizer;
if (au->secret_id < th->secret_id) {
dout("ceph_x_update_authorizer service %u secret %llu < %llu\n",
au->service, au->secret_id, th->secret_id);
return ceph_x_build_authorizer(ac, th, au);
}
return 0;
}
static int ceph_x_verify_authorizer_reply(struct ceph_auth_client *ac,
struct ceph_authorizer *a)
{
struct ceph_x_authorizer *au = (void *)a;
void *p = au->enc_buf;
struct ceph_x_authorize_reply *reply = p + ceph_x_encrypt_offset();
int ret;
ret = ceph_x_decrypt(&au->session_key, &p, p + CEPHX_AU_ENC_BUF_LEN);
if (ret < 0)
return ret;
if (ret != sizeof(*reply))
return -EPERM;
if (au->nonce + 1 != le64_to_cpu(reply->nonce_plus_one))
ret = -EPERM;
else
ret = 0;
dout("verify_authorizer_reply nonce %llx got %llx ret %d\n",
au->nonce, le64_to_cpu(reply->nonce_plus_one), ret);
return ret;
}
static void ceph_x_reset(struct ceph_auth_client *ac)
{
struct ceph_x_info *xi = ac->private;
dout("reset\n");
xi->starting = true;
xi->server_challenge = 0;
}
static void ceph_x_destroy(struct ceph_auth_client *ac)
{
struct ceph_x_info *xi = ac->private;
struct rb_node *p;
dout("ceph_x_destroy %p\n", ac);
ceph_crypto_key_destroy(&xi->secret);
while ((p = rb_first(&xi->ticket_handlers)) != NULL) {
struct ceph_x_ticket_handler *th =
rb_entry(p, struct ceph_x_ticket_handler, node);
remove_ticket_handler(ac, th);
}
ceph_x_authorizer_cleanup(&xi->auth_authorizer);
kfree(ac->private);
ac->private = NULL;
}
static void invalidate_ticket(struct ceph_auth_client *ac, int peer_type)
{
struct ceph_x_ticket_handler *th;
th = get_ticket_handler(ac, peer_type);
if (!IS_ERR(th))
th->have_key = false;
}
static void ceph_x_invalidate_authorizer(struct ceph_auth_client *ac,
int peer_type)
{
/*
* We are to invalidate a service ticket in the hopes of
* getting a new, hopefully more valid, one. But, we won't get
* it unless our AUTH ticket is good, so invalidate AUTH ticket
* as well, just in case.
*/
invalidate_ticket(ac, peer_type);
invalidate_ticket(ac, CEPH_ENTITY_TYPE_AUTH);
}
static int calc_signature(struct ceph_x_authorizer *au, struct ceph_msg *msg,
__le64 *psig)
{
void *enc_buf = au->enc_buf;
struct {
__le32 len;
__le32 header_crc;
__le32 front_crc;
__le32 middle_crc;
__le32 data_crc;
} __packed *sigblock = enc_buf + ceph_x_encrypt_offset();
int ret;
sigblock->len = cpu_to_le32(4*sizeof(u32));
sigblock->header_crc = msg->hdr.crc;
sigblock->front_crc = msg->footer.front_crc;
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));
if (ret < 0)
return ret;
*psig = *(__le64 *)(enc_buf + sizeof(u32));
return 0;
}
static int ceph_x_sign_message(struct ceph_auth_handshake *auth,
struct ceph_msg *msg)
{
__le64 sig;
int ret;
if (ceph_test_opt(from_msgr(msg->con->msgr), NOMSGSIGN))
return 0;
ret = calc_signature((struct ceph_x_authorizer *)auth->authorizer,
msg, &sig);
if (ret)
return ret;
msg->footer.sig = sig;
msg->footer.flags |= CEPH_MSG_FOOTER_SIGNED;
return 0;
}
static int ceph_x_check_message_signature(struct ceph_auth_handshake *auth,
struct ceph_msg *msg)
{
__le64 sig_check;
int ret;
if (ceph_test_opt(from_msgr(msg->con->msgr), NOMSGSIGN))
return 0;
ret = calc_signature((struct ceph_x_authorizer *)auth->authorizer,
msg, &sig_check);
if (ret)
return ret;
if (sig_check == msg->footer.sig)
return 0;
if (msg->footer.flags & CEPH_MSG_FOOTER_SIGNED)
dout("ceph_x_check_message_signature %p has signature %llx "
"expect %llx\n", msg, msg->footer.sig, sig_check);
else
dout("ceph_x_check_message_signature %p sender did not set "
"CEPH_MSG_FOOTER_SIGNED\n", msg);
return -EBADMSG;
}
static const struct ceph_auth_client_ops ceph_x_ops = {
.name = "x",
.is_authenticated = ceph_x_is_authenticated,
.should_authenticate = ceph_x_should_authenticate,
.build_request = ceph_x_build_request,
.handle_reply = ceph_x_handle_reply,
.create_authorizer = ceph_x_create_authorizer,
.update_authorizer = ceph_x_update_authorizer,
.verify_authorizer_reply = ceph_x_verify_authorizer_reply,
.invalidate_authorizer = ceph_x_invalidate_authorizer,
.reset = ceph_x_reset,
.destroy = ceph_x_destroy,
.sign_message = ceph_x_sign_message,
.check_message_signature = ceph_x_check_message_signature,
};
int ceph_x_init(struct ceph_auth_client *ac)
{
struct ceph_x_info *xi;
int ret;
dout("ceph_x_init %p\n", ac);
ret = -ENOMEM;
xi = kzalloc(sizeof(*xi), GFP_NOFS);
if (!xi)
goto out;
ret = -EINVAL;
if (!ac->key) {
pr_err("no secret set (for auth_x protocol)\n");
goto out_nomem;
}
ret = ceph_crypto_key_clone(&xi->secret, ac->key);
if (ret < 0) {
pr_err("cannot clone key: %d\n", ret);
goto out_nomem;
}
xi->starting = true;
xi->ticket_handlers = RB_ROOT;
ac->protocol = CEPH_AUTH_CEPHX;
ac->private = xi;
ac->ops = &ceph_x_ops;
return 0;
out_nomem:
kfree(xi);
out:
return ret;
}