![David Howells](/assets/img/avatar_default.png)
Search functions pass around a bunch of arguments, each of which gets copied with each call. Introduce a search context structure to hold these. Whilst we're at it, create a search flag that indicates whether the search should be directly to the description or whether it should iterate through all keys looking for a non-description match. This will be useful when keyrings use a generic data struct with generic routines to manage their content as the search terms can just be passed through to the iterator callback function. Also, for future use, the data to be supplied to the match function is separated from the description pointer in the search context. This makes it clear which is being supplied. Signed-off-by: David Howells <dhowells@redhat.com>
270 lines
6.7 KiB
C
270 lines
6.7 KiB
C
/* 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 (dhowells@redhat.com)
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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* See Documentation/security/keys-request-key.txt
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*/
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#include <linux/module.h>
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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 <asm/uaccess.h>
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#include "internal.h"
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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 __user *, 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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.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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/*
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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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key->payload.data = (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 = key->payload.data;
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seq_puts(m, "key:");
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seq_puts(m, key->description);
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if (key_is_instantiated(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 __user *buffer, size_t buflen)
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{
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struct request_key_auth *rka = key->payload.data;
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size_t datalen;
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long ret;
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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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if (copy_to_user(buffer, rka->callout_info, buflen) != 0)
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ret = -EFAULT;
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}
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return ret;
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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 = key->payload.data;
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kenter("{%d}", key->serial);
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if (rka->cred) {
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put_cred(rka->cred);
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rka->cred = NULL;
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}
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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 = key->payload.data;
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kenter("{%d}", key->serial);
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if (rka->cred) {
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put_cred(rka->cred);
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rka->cred = NULL;
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}
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key_put(rka->target_key);
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key_put(rka->dest_keyring);
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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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* 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 void *callout_info,
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size_t callout_len, 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;
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kenter("%d,", target->serial);
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/* allocate a auth record */
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rka = kmalloc(sizeof(*rka), GFP_KERNEL);
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if (!rka) {
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kleave(" = -ENOMEM");
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return ERR_PTR(-ENOMEM);
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}
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rka->callout_info = kmalloc(callout_len, GFP_KERNEL);
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if (!rka->callout_info) {
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kleave(" = -ENOMEM");
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kfree(rka);
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return ERR_PTR(-ENOMEM);
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}
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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, &cred->request_key_auth->flags))
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goto auth_key_revoked;
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irka = cred->request_key_auth->payload.data;
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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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memcpy(rka->callout_info, callout_info, callout_len);
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rka->callout_len = callout_len;
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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 |
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KEY_USR_VIEW, KEY_ALLOC_NOT_IN_QUOTA);
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if (IS_ERR(authkey)) {
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ret = PTR_ERR(authkey);
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goto error_alloc;
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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_inst;
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kleave(" = {%d,%d}", authkey->serial, atomic_read(&authkey->usage));
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return authkey;
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auth_key_revoked:
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up_read(&cred->request_key_auth->sem);
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kfree(rka->callout_info);
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kfree(rka);
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kleave("= -EKEYREVOKED");
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return ERR_PTR(-EKEYREVOKED);
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error_inst:
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key_revoke(authkey);
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key_put(authkey);
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error_alloc:
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key_put(rka->target_key);
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key_put(rka->dest_keyring);
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kfree(rka->callout_info);
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kfree(rka);
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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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* See if an authorisation key is associated with a particular key.
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*/
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static int key_get_instantiation_authkey_match(const struct key *key,
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const void *_id)
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{
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struct request_key_auth *rka = key->payload.data;
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key_serial_t id = (key_serial_t)(unsigned long) _id;
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return rka->target_key->serial == id;
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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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struct keyring_search_context ctx = {
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.index_key.type = &key_type_request_key_auth,
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.cred = current_cred(),
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.match = key_get_instantiation_authkey_match,
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.match_data = (void *)(unsigned long)target_id,
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.flags = KEYRING_SEARCH_LOOKUP_DIRECT,
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};
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struct key *authkey;
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key_ref_t authkey_ref;
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authkey_ref = search_process_keyrings(&ctx);
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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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