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![Ilya Dryomov](/assets/img/avatar_default.png)
When a client authenticates with a service, an authorizer is sent with a nonce to the service (ceph_x_authorize_[ab]) and the service responds with a mutation of that nonce (ceph_x_authorize_reply). This lets the client verify the service is who it says it is but it doesn't protect against a replay: someone can trivially capture the exchange and reuse the same authorizer to authenticate themselves. Allow the service to reject an initial authorizer with a random challenge (ceph_x_authorize_challenge). The client then has to respond with an updated authorizer proving they are able to decrypt the service's challenge and that the new authorizer was produced for this specific connection instance. The accepting side requires this challenge and response unconditionally if the client side advertises they have CEPHX_V2 feature bit. This addresses CVE-2018-1128. Link: http://tracker.ceph.com/issues/24836 Signed-off-by: Ilya Dryomov <idryomov@gmail.com> Reviewed-by: Sage Weil <sage@redhat.com>
354 lines
7.9 KiB
C
354 lines
7.9 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#include <linux/ceph/ceph_debug.h>
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#include <linux/module.h>
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#include <linux/err.h>
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#include <linux/slab.h>
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#include <linux/ceph/types.h>
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#include <linux/ceph/decode.h>
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#include <linux/ceph/libceph.h>
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#include <linux/ceph/messenger.h>
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#include "auth_none.h"
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#include "auth_x.h"
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/*
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* get protocol handler
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*/
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static u32 supported_protocols[] = {
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CEPH_AUTH_NONE,
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CEPH_AUTH_CEPHX
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};
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static int ceph_auth_init_protocol(struct ceph_auth_client *ac, int protocol)
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{
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switch (protocol) {
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case CEPH_AUTH_NONE:
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return ceph_auth_none_init(ac);
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case CEPH_AUTH_CEPHX:
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return ceph_x_init(ac);
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default:
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return -ENOENT;
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}
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}
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/*
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* setup, teardown.
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*/
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struct ceph_auth_client *ceph_auth_init(const char *name, const struct ceph_crypto_key *key)
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{
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struct ceph_auth_client *ac;
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int ret;
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dout("auth_init name '%s'\n", name);
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ret = -ENOMEM;
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ac = kzalloc(sizeof(*ac), GFP_NOFS);
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if (!ac)
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goto out;
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mutex_init(&ac->mutex);
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ac->negotiating = true;
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if (name)
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ac->name = name;
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else
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ac->name = CEPH_AUTH_NAME_DEFAULT;
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dout("auth_init name %s\n", ac->name);
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ac->key = key;
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return ac;
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out:
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return ERR_PTR(ret);
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}
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void ceph_auth_destroy(struct ceph_auth_client *ac)
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{
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dout("auth_destroy %p\n", ac);
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if (ac->ops)
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ac->ops->destroy(ac);
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kfree(ac);
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}
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/*
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* Reset occurs when reconnecting to the monitor.
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*/
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void ceph_auth_reset(struct ceph_auth_client *ac)
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{
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mutex_lock(&ac->mutex);
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dout("auth_reset %p\n", ac);
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if (ac->ops && !ac->negotiating)
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ac->ops->reset(ac);
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ac->negotiating = true;
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mutex_unlock(&ac->mutex);
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}
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/*
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* EntityName, not to be confused with entity_name_t
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*/
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int ceph_auth_entity_name_encode(const char *name, void **p, void *end)
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{
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int len = strlen(name);
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if (*p + 2*sizeof(u32) + len > end)
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return -ERANGE;
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ceph_encode_32(p, CEPH_ENTITY_TYPE_CLIENT);
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ceph_encode_32(p, len);
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ceph_encode_copy(p, name, len);
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return 0;
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}
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/*
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* Initiate protocol negotiation with monitor. Include entity name
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* and list supported protocols.
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*/
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int ceph_auth_build_hello(struct ceph_auth_client *ac, void *buf, size_t len)
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{
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struct ceph_mon_request_header *monhdr = buf;
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void *p = monhdr + 1, *end = buf + len, *lenp;
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int i, num;
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int ret;
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mutex_lock(&ac->mutex);
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dout("auth_build_hello\n");
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monhdr->have_version = 0;
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monhdr->session_mon = cpu_to_le16(-1);
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monhdr->session_mon_tid = 0;
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ceph_encode_32(&p, CEPH_AUTH_UNKNOWN); /* no protocol, yet */
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lenp = p;
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p += sizeof(u32);
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ceph_decode_need(&p, end, 1 + sizeof(u32), bad);
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ceph_encode_8(&p, 1);
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num = ARRAY_SIZE(supported_protocols);
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ceph_encode_32(&p, num);
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ceph_decode_need(&p, end, num * sizeof(u32), bad);
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for (i = 0; i < num; i++)
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ceph_encode_32(&p, supported_protocols[i]);
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ret = ceph_auth_entity_name_encode(ac->name, &p, end);
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if (ret < 0)
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goto out;
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ceph_decode_need(&p, end, sizeof(u64), bad);
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ceph_encode_64(&p, ac->global_id);
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ceph_encode_32(&lenp, p - lenp - sizeof(u32));
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ret = p - buf;
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out:
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mutex_unlock(&ac->mutex);
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return ret;
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bad:
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ret = -ERANGE;
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goto out;
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}
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static int ceph_build_auth_request(struct ceph_auth_client *ac,
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void *msg_buf, size_t msg_len)
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{
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struct ceph_mon_request_header *monhdr = msg_buf;
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void *p = monhdr + 1;
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void *end = msg_buf + msg_len;
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int ret;
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monhdr->have_version = 0;
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monhdr->session_mon = cpu_to_le16(-1);
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monhdr->session_mon_tid = 0;
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ceph_encode_32(&p, ac->protocol);
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ret = ac->ops->build_request(ac, p + sizeof(u32), end);
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if (ret < 0) {
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pr_err("error %d building auth method %s request\n", ret,
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ac->ops->name);
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goto out;
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}
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dout(" built request %d bytes\n", ret);
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ceph_encode_32(&p, ret);
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ret = p + ret - msg_buf;
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out:
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return ret;
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}
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/*
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* Handle auth message from monitor.
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*/
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int ceph_handle_auth_reply(struct ceph_auth_client *ac,
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void *buf, size_t len,
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void *reply_buf, size_t reply_len)
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{
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void *p = buf;
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void *end = buf + len;
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int protocol;
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s32 result;
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u64 global_id;
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void *payload, *payload_end;
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int payload_len;
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char *result_msg;
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int result_msg_len;
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int ret = -EINVAL;
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mutex_lock(&ac->mutex);
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dout("handle_auth_reply %p %p\n", p, end);
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ceph_decode_need(&p, end, sizeof(u32) * 3 + sizeof(u64), bad);
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protocol = ceph_decode_32(&p);
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result = ceph_decode_32(&p);
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global_id = ceph_decode_64(&p);
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payload_len = ceph_decode_32(&p);
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payload = p;
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p += payload_len;
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ceph_decode_need(&p, end, sizeof(u32), bad);
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result_msg_len = ceph_decode_32(&p);
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result_msg = p;
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p += result_msg_len;
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if (p != end)
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goto bad;
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dout(" result %d '%.*s' gid %llu len %d\n", result, result_msg_len,
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result_msg, global_id, payload_len);
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payload_end = payload + payload_len;
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if (global_id && ac->global_id != global_id) {
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dout(" set global_id %lld -> %lld\n", ac->global_id, global_id);
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ac->global_id = global_id;
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}
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if (ac->negotiating) {
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/* server does not support our protocols? */
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if (!protocol && result < 0) {
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ret = result;
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goto out;
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}
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/* set up (new) protocol handler? */
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if (ac->protocol && ac->protocol != protocol) {
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ac->ops->destroy(ac);
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ac->protocol = 0;
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ac->ops = NULL;
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}
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if (ac->protocol != protocol) {
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ret = ceph_auth_init_protocol(ac, protocol);
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if (ret) {
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pr_err("error %d on auth protocol %d init\n",
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ret, protocol);
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goto out;
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}
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}
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ac->negotiating = false;
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}
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ret = ac->ops->handle_reply(ac, result, payload, payload_end);
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if (ret == -EAGAIN) {
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ret = ceph_build_auth_request(ac, reply_buf, reply_len);
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} else if (ret) {
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pr_err("auth method '%s' error %d\n", ac->ops->name, ret);
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}
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out:
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mutex_unlock(&ac->mutex);
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return ret;
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bad:
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pr_err("failed to decode auth msg\n");
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ret = -EINVAL;
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goto out;
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}
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int ceph_build_auth(struct ceph_auth_client *ac,
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void *msg_buf, size_t msg_len)
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{
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int ret = 0;
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mutex_lock(&ac->mutex);
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if (ac->ops->should_authenticate(ac))
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ret = ceph_build_auth_request(ac, msg_buf, msg_len);
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mutex_unlock(&ac->mutex);
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return ret;
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}
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int ceph_auth_is_authenticated(struct ceph_auth_client *ac)
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{
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int ret = 0;
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mutex_lock(&ac->mutex);
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if (ac->ops)
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ret = ac->ops->is_authenticated(ac);
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mutex_unlock(&ac->mutex);
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return ret;
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}
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EXPORT_SYMBOL(ceph_auth_is_authenticated);
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int ceph_auth_create_authorizer(struct ceph_auth_client *ac,
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int peer_type,
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struct ceph_auth_handshake *auth)
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{
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int ret = 0;
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mutex_lock(&ac->mutex);
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if (ac->ops && ac->ops->create_authorizer)
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ret = ac->ops->create_authorizer(ac, peer_type, auth);
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mutex_unlock(&ac->mutex);
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return ret;
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}
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EXPORT_SYMBOL(ceph_auth_create_authorizer);
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void ceph_auth_destroy_authorizer(struct ceph_authorizer *a)
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{
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a->destroy(a);
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}
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EXPORT_SYMBOL(ceph_auth_destroy_authorizer);
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int ceph_auth_update_authorizer(struct ceph_auth_client *ac,
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int peer_type,
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struct ceph_auth_handshake *a)
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{
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int ret = 0;
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mutex_lock(&ac->mutex);
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if (ac->ops && ac->ops->update_authorizer)
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ret = ac->ops->update_authorizer(ac, peer_type, a);
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mutex_unlock(&ac->mutex);
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return ret;
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}
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EXPORT_SYMBOL(ceph_auth_update_authorizer);
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int ceph_auth_add_authorizer_challenge(struct ceph_auth_client *ac,
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struct ceph_authorizer *a,
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void *challenge_buf,
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int challenge_buf_len)
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{
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int ret = 0;
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mutex_lock(&ac->mutex);
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if (ac->ops && ac->ops->add_authorizer_challenge)
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ret = ac->ops->add_authorizer_challenge(ac, a, challenge_buf,
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challenge_buf_len);
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mutex_unlock(&ac->mutex);
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return ret;
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}
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EXPORT_SYMBOL(ceph_auth_add_authorizer_challenge);
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int ceph_auth_verify_authorizer_reply(struct ceph_auth_client *ac,
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struct ceph_authorizer *a)
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{
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int ret = 0;
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mutex_lock(&ac->mutex);
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if (ac->ops && ac->ops->verify_authorizer_reply)
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ret = ac->ops->verify_authorizer_reply(ac, a);
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mutex_unlock(&ac->mutex);
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return ret;
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}
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EXPORT_SYMBOL(ceph_auth_verify_authorizer_reply);
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void ceph_auth_invalidate_authorizer(struct ceph_auth_client *ac, int peer_type)
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{
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mutex_lock(&ac->mutex);
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if (ac->ops && ac->ops->invalidate_authorizer)
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ac->ops->invalidate_authorizer(ac, peer_type);
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mutex_unlock(&ac->mutex);
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}
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EXPORT_SYMBOL(ceph_auth_invalidate_authorizer);
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