269 lines
7.2 KiB
C
269 lines
7.2 KiB
C
/* request_key_auth.c: request key authorisation controlling key def
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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/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 <asm/uaccess.h>
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#include "internal.h"
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static int request_key_auth_instantiate(struct key *, const void *, size_t);
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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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/*
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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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const void *data,
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size_t datalen)
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{
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key->payload.data = (struct request_key_auth *) data;
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return 0;
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} /* end request_key_auth_instantiate() */
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/*****************************************************************************/
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/*
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* reading a request-key authorisation key retrieves the callout information
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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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seq_printf(m, " pid:%d ci:%zu", rka->pid, strlen(rka->callout_info));
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} /* end request_key_auth_describe() */
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/*****************************************************************************/
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/*
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* read the callout_info data
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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 = strlen(rka->callout_info);
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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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} /* end request_key_auth_read() */
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/*****************************************************************************/
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/*
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* handle revocation of an authorisation token key
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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->context) {
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put_task_struct(rka->context);
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rka->context = NULL;
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}
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} /* end request_key_auth_revoke() */
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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->context) {
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put_task_struct(rka->context);
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rka->context = NULL;
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}
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key_put(rka->target_key);
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kfree(rka);
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} /* end request_key_auth_destroy() */
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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 *callout_info)
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{
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struct request_key_auth *rka, *irka;
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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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/* see if the calling process is already servicing the key request of
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* another process */
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if (current->request_key_auth) {
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/* it is - use that instantiation context here too */
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down_read(¤t->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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¤t->request_key_auth->flags))
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goto auth_key_revoked;
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irka = current->request_key_auth->payload.data;
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rka->context = irka->context;
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rka->pid = irka->pid;
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get_task_struct(rka->context);
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up_read(¤t->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->context = current;
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rka->pid = current->pid;
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get_task_struct(rka->context);
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}
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rka->target_key = key_get(target);
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rka->callout_info = callout_info;
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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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current->fsuid, current->fsgid, current,
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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 and attach to the keyring */
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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}", authkey->serial);
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return authkey;
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auth_key_revoked:
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up_read(¤t->request_key_auth->sem);
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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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kfree(rka);
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kleave("= %d", ret);
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return ERR_PTR(ret);
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} /* end request_key_auth_new() */
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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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} /* end key_get_instantiation_authkey_match() */
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/*****************************************************************************/
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/*
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* get the authorisation key for instantiation of a specific key if attached to
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* the current process's keyrings
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* - this key is inserted into a keyring and that is set as /sbin/request-key's
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* session keyring
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* - a target_id of zero specifies any valid token
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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 key *authkey;
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key_ref_t authkey_ref;
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authkey_ref = search_process_keyrings(
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&key_type_request_key_auth,
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(void *) (unsigned long) target_id,
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key_get_instantiation_authkey_match,
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current);
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if (IS_ERR(authkey_ref)) {
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authkey = ERR_PTR(PTR_ERR(authkey_ref));
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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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} /* end key_get_instantiation_authkey() */
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