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-rw-r--r--security/keys/request_key_auth.c180
1 files changed, 180 insertions, 0 deletions
diff --git a/security/keys/request_key_auth.c b/security/keys/request_key_auth.c
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--- /dev/null
+++ b/security/keys/request_key_auth.c
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+/* request_key_auth.c: request key authorisation controlling key def
+ *
+ * Copyright (C) 2005 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/err.h>
+#include <linux/seq_file.h>
+#include "internal.h"
+
+static int request_key_auth_instantiate(struct key *, const void *, size_t);
+static void request_key_auth_describe(const struct key *, struct seq_file *);
+static void request_key_auth_destroy(struct key *);
+
+/*
+ * the request-key authorisation key type definition
+ */
+struct key_type key_type_request_key_auth = {
+ .name = ".request_key_auth",
+ .def_datalen = sizeof(struct request_key_auth),
+ .instantiate = request_key_auth_instantiate,
+ .describe = request_key_auth_describe,
+ .destroy = request_key_auth_destroy,
+};
+
+/*****************************************************************************/
+/*
+ * instantiate a request-key authorisation record
+ */
+static int request_key_auth_instantiate(struct key *key,
+ const void *data,
+ size_t datalen)
+{
+ struct request_key_auth *rka, *irka;
+ struct key *instkey;
+ int ret;
+
+ ret = -ENOMEM;
+ rka = kmalloc(sizeof(*rka), GFP_KERNEL);
+ if (rka) {
+ /* see if the calling process is already servicing the key
+ * request of another process */
+ instkey = key_get_instantiation_authkey(0);
+ if (!IS_ERR(instkey)) {
+ /* it is - use that instantiation context here too */
+ irka = instkey->payload.data;
+ rka->context = irka->context;
+ rka->pid = irka->pid;
+ key_put(instkey);
+ }
+ else {
+ /* it isn't - use this process as the context */
+ rka->context = current;
+ rka->pid = current->pid;
+ }
+
+ rka->target_key = key_get((struct key *) data);
+ key->payload.data = rka;
+ ret = 0;
+ }
+
+ return ret;
+
+} /* end request_key_auth_instantiate() */
+
+/*****************************************************************************/
+/*
+ *
+ */
+static void request_key_auth_describe(const struct key *key,
+ struct seq_file *m)
+{
+ struct request_key_auth *rka = key->payload.data;
+
+ seq_puts(m, "key:");
+ seq_puts(m, key->description);
+ seq_printf(m, " pid:%d", rka->pid);
+
+} /* end request_key_auth_describe() */
+
+/*****************************************************************************/
+/*
+ * destroy an instantiation authorisation token key
+ */
+static void request_key_auth_destroy(struct key *key)
+{
+ struct request_key_auth *rka = key->payload.data;
+
+ kenter("{%d}", key->serial);
+
+ key_put(rka->target_key);
+
+} /* end request_key_auth_destroy() */
+
+/*****************************************************************************/
+/*
+ * create a session keyring to be for the invokation of /sbin/request-key and
+ * stick an authorisation token in it
+ */
+struct key *request_key_auth_new(struct key *target, struct key **_rkakey)
+{
+ struct key *keyring, *rkakey = NULL;
+ char desc[20];
+ int ret;
+
+ kenter("%d,", target->serial);
+
+ /* allocate a new session keyring */
+ sprintf(desc, "_req.%u", target->serial);
+
+ keyring = keyring_alloc(desc, current->fsuid, current->fsgid, 1, NULL);
+ if (IS_ERR(keyring)) {
+ kleave("= %ld", PTR_ERR(keyring));
+ return keyring;
+ }
+
+ /* allocate the auth key */
+ sprintf(desc, "%x", target->serial);
+
+ rkakey = key_alloc(&key_type_request_key_auth, desc,
+ current->fsuid, current->fsgid,
+ KEY_USR_VIEW, 1);
+ if (IS_ERR(rkakey)) {
+ key_put(keyring);
+ kleave("= %ld", PTR_ERR(rkakey));
+ return rkakey;
+ }
+
+ /* construct and attach to the keyring */
+ ret = key_instantiate_and_link(rkakey, target, 0, keyring, NULL);
+ if (ret < 0) {
+ key_revoke(rkakey);
+ key_put(rkakey);
+ key_put(keyring);
+ kleave("= %d", ret);
+ return ERR_PTR(ret);
+ }
+
+ *_rkakey = rkakey;
+ kleave(" = {%d} ({%d})", keyring->serial, rkakey->serial);
+ return keyring;
+
+} /* end request_key_auth_new() */
+
+/*****************************************************************************/
+/*
+ * get the authorisation key for instantiation of a specific key if attached to
+ * the current process's keyrings
+ * - this key is inserted into a keyring and that is set as /sbin/request-key's
+ * session keyring
+ * - a target_id of zero specifies any valid token
+ */
+struct key *key_get_instantiation_authkey(key_serial_t target_id)
+{
+ struct task_struct *tsk = current;
+ struct key *instkey;
+
+ /* we must have our own personal session keyring */
+ if (!tsk->signal->session_keyring)
+ return ERR_PTR(-EACCES);
+
+ /* and it must contain a suitable request authorisation key
+ * - lock RCU against session keyring changing
+ */
+ rcu_read_lock();
+
+ instkey = keyring_search_instkey(
+ rcu_dereference(tsk->signal->session_keyring), target_id);
+
+ rcu_read_unlock();
+ return instkey;
+
+} /* end key_get_instantiation_authkey() */
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