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283 lines
7.1 KiB
283 lines
7.1 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
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/* Request key authorisation token key definition. |
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* |
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* Copyright (C) 2005 Red Hat, Inc. All Rights Reserved. |
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* Written by David Howells ([email protected]) |
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* |
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* See Documentation/security/keys/request-key.rst |
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*/ |
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#include <linux/sched.h> |
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#include <linux/err.h> |
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#include <linux/seq_file.h> |
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#include <linux/slab.h> |
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#include <linux/uaccess.h> |
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#include "internal.h" |
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#include <keys/request_key_auth-type.h> |
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static int request_key_auth_preparse(struct key_preparsed_payload *); |
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static void request_key_auth_free_preparse(struct key_preparsed_payload *); |
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static int request_key_auth_instantiate(struct key *, |
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struct key_preparsed_payload *); |
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static void request_key_auth_describe(const struct key *, struct seq_file *); |
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static void request_key_auth_revoke(struct key *); |
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static void request_key_auth_destroy(struct key *); |
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static long request_key_auth_read(const struct key *, char *, size_t); |
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/* |
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* The request-key authorisation key type definition. |
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*/ |
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struct key_type key_type_request_key_auth = { |
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.name = ".request_key_auth", |
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.def_datalen = sizeof(struct request_key_auth), |
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.preparse = request_key_auth_preparse, |
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.free_preparse = request_key_auth_free_preparse, |
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.instantiate = request_key_auth_instantiate, |
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.describe = request_key_auth_describe, |
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.revoke = request_key_auth_revoke, |
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.destroy = request_key_auth_destroy, |
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.read = request_key_auth_read, |
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}; |
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static int request_key_auth_preparse(struct key_preparsed_payload *prep) |
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{ |
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return 0; |
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} |
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static void request_key_auth_free_preparse(struct key_preparsed_payload *prep) |
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{ |
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} |
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/* |
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* Instantiate a request-key authorisation key. |
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*/ |
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static int request_key_auth_instantiate(struct key *key, |
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struct key_preparsed_payload *prep) |
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{ |
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rcu_assign_keypointer(key, (struct request_key_auth *)prep->data); |
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return 0; |
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} |
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/* |
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* Describe an authorisation token. |
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*/ |
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static void request_key_auth_describe(const struct key *key, |
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struct seq_file *m) |
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{ |
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struct request_key_auth *rka = dereference_key_rcu(key); |
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if (!rka) |
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return; |
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seq_puts(m, "key:"); |
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seq_puts(m, key->description); |
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if (key_is_positive(key)) |
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seq_printf(m, " pid:%d ci:%zu", rka->pid, rka->callout_len); |
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} |
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/* |
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* Read the callout_info data (retrieves the callout information). |
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* - the key's semaphore is read-locked |
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*/ |
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static long request_key_auth_read(const struct key *key, |
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char *buffer, size_t buflen) |
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{ |
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struct request_key_auth *rka = dereference_key_locked(key); |
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size_t datalen; |
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long ret; |
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if (!rka) |
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return -EKEYREVOKED; |
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datalen = rka->callout_len; |
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ret = datalen; |
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/* we can return the data as is */ |
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if (buffer && buflen > 0) { |
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if (buflen > datalen) |
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buflen = datalen; |
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memcpy(buffer, rka->callout_info, buflen); |
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} |
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return ret; |
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} |
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static void free_request_key_auth(struct request_key_auth *rka) |
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{ |
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if (!rka) |
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return; |
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key_put(rka->target_key); |
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key_put(rka->dest_keyring); |
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if (rka->cred) |
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put_cred(rka->cred); |
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kfree(rka->callout_info); |
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kfree(rka); |
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} |
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/* |
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* Dispose of the request_key_auth record under RCU conditions |
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*/ |
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static void request_key_auth_rcu_disposal(struct rcu_head *rcu) |
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{ |
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struct request_key_auth *rka = |
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container_of(rcu, struct request_key_auth, rcu); |
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free_request_key_auth(rka); |
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} |
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/* |
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* Handle revocation of an authorisation token key. |
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* |
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* Called with the key sem write-locked. |
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*/ |
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static void request_key_auth_revoke(struct key *key) |
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{ |
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struct request_key_auth *rka = dereference_key_locked(key); |
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kenter("{%d}", key->serial); |
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rcu_assign_keypointer(key, NULL); |
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call_rcu(&rka->rcu, request_key_auth_rcu_disposal); |
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} |
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/* |
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* Destroy an instantiation authorisation token key. |
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*/ |
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static void request_key_auth_destroy(struct key *key) |
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{ |
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struct request_key_auth *rka = rcu_access_pointer(key->payload.rcu_data0); |
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kenter("{%d}", key->serial); |
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if (rka) { |
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rcu_assign_keypointer(key, NULL); |
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call_rcu(&rka->rcu, request_key_auth_rcu_disposal); |
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} |
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} |
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/* |
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* Create an authorisation token for /sbin/request-key or whoever to gain |
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* access to the caller's security data. |
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*/ |
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struct key *request_key_auth_new(struct key *target, const char *op, |
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const void *callout_info, size_t callout_len, |
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struct key *dest_keyring) |
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{ |
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struct request_key_auth *rka, *irka; |
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const struct cred *cred = current_cred(); |
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struct key *authkey = NULL; |
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char desc[20]; |
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int ret = -ENOMEM; |
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kenter("%d,", target->serial); |
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/* allocate a auth record */ |
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rka = kzalloc(sizeof(*rka), GFP_KERNEL); |
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if (!rka) |
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goto error; |
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rka->callout_info = kmemdup(callout_info, callout_len, GFP_KERNEL); |
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if (!rka->callout_info) |
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goto error_free_rka; |
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rka->callout_len = callout_len; |
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strlcpy(rka->op, op, sizeof(rka->op)); |
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/* see if the calling process is already servicing the key request of |
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* another process */ |
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if (cred->request_key_auth) { |
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/* it is - use that instantiation context here too */ |
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down_read(&cred->request_key_auth->sem); |
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/* if the auth key has been revoked, then the key we're |
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* servicing is already instantiated */ |
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if (test_bit(KEY_FLAG_REVOKED, |
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&cred->request_key_auth->flags)) { |
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up_read(&cred->request_key_auth->sem); |
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ret = -EKEYREVOKED; |
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goto error_free_rka; |
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} |
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irka = cred->request_key_auth->payload.data[0]; |
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rka->cred = get_cred(irka->cred); |
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rka->pid = irka->pid; |
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up_read(&cred->request_key_auth->sem); |
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} |
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else { |
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/* it isn't - use this process as the context */ |
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rka->cred = get_cred(cred); |
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rka->pid = current->pid; |
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} |
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rka->target_key = key_get(target); |
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rka->dest_keyring = key_get(dest_keyring); |
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/* allocate the auth key */ |
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sprintf(desc, "%x", target->serial); |
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authkey = key_alloc(&key_type_request_key_auth, desc, |
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cred->fsuid, cred->fsgid, cred, |
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KEY_POS_VIEW | KEY_POS_READ | KEY_POS_SEARCH | KEY_POS_LINK | |
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KEY_USR_VIEW, KEY_ALLOC_NOT_IN_QUOTA, NULL); |
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if (IS_ERR(authkey)) { |
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ret = PTR_ERR(authkey); |
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goto error_free_rka; |
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} |
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/* construct the auth key */ |
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ret = key_instantiate_and_link(authkey, rka, 0, NULL, NULL); |
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if (ret < 0) |
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goto error_put_authkey; |
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kleave(" = {%d,%d}", authkey->serial, refcount_read(&authkey->usage)); |
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return authkey; |
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error_put_authkey: |
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key_put(authkey); |
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error_free_rka: |
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free_request_key_auth(rka); |
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error: |
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kleave("= %d", ret); |
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return ERR_PTR(ret); |
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} |
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/* |
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* Search the current process's keyrings for the authorisation key for |
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* instantiation of a key. |
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*/ |
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struct key *key_get_instantiation_authkey(key_serial_t target_id) |
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{ |
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char description[16]; |
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struct keyring_search_context ctx = { |
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.index_key.type = &key_type_request_key_auth, |
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.index_key.description = description, |
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.cred = current_cred(), |
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.match_data.cmp = key_default_cmp, |
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.match_data.raw_data = description, |
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.match_data.lookup_type = KEYRING_SEARCH_LOOKUP_DIRECT, |
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.flags = (KEYRING_SEARCH_DO_STATE_CHECK | |
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KEYRING_SEARCH_RECURSE), |
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}; |
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struct key *authkey; |
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key_ref_t authkey_ref; |
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ctx.index_key.desc_len = sprintf(description, "%x", target_id); |
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rcu_read_lock(); |
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authkey_ref = search_process_keyrings_rcu(&ctx); |
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rcu_read_unlock(); |
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if (IS_ERR(authkey_ref)) { |
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authkey = ERR_CAST(authkey_ref); |
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if (authkey == ERR_PTR(-EAGAIN)) |
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authkey = ERR_PTR(-ENOKEY); |
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goto error; |
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} |
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authkey = key_ref_to_ptr(authkey_ref); |
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if (test_bit(KEY_FLAG_REVOKED, &authkey->flags)) { |
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key_put(authkey); |
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authkey = ERR_PTR(-EKEYREVOKED); |
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} |
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error: |
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return authkey; |
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}
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