1 files changed, 359 insertions, 0 deletions
diff --git a/security/keys/request_key.c b/security/keys/request_key.c
new file mode 100644
index 00000000000..9705b1aeba5
--- /dev/null
+++ b/security/keys/request_key.c
@@ -0,0 +1,359 @@
+/* request_key.c: request a key from userspace
+ *
+ * Copyright (C) 2004 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/kmod.h>
+#include <linux/err.h>
+#include "internal.h"
+
+struct key_construction {
+	struct list_head	link;	/* link in construction queue */
+	struct key		*key;	/* key being constructed */
+};
+
+/* when waiting for someone else's keys, you get added to this */
+DECLARE_WAIT_QUEUE_HEAD(request_key_conswq);
+
+/*****************************************************************************/
+/*
+ * request userspace finish the construction of a key
+ * - execute "/sbin/request-key <op> <key> <uid> <gid> <keyring> <keyring> <keyring> <info>"
+ * - if callout_info is an empty string, it'll be rendered as a "-" instead
+ */
+static int call_request_key(struct key *key,
+			    const char *op,
+			    const char *callout_info)
+{
+	struct task_struct *tsk = current;
+	unsigned long flags;
+	key_serial_t prkey, sskey;
+	char *argv[10], *envp[3], uid_str[12], gid_str[12];
+	char key_str[12], keyring_str[3][12];
+	int i;
+
+	/* record the UID and GID */
+	sprintf(uid_str, "%d", current->fsuid);
+	sprintf(gid_str, "%d", current->fsgid);
+
+	/* we say which key is under construction */
+	sprintf(key_str, "%d", key->serial);
+
+	/* we specify the process's default keyrings */
+	sprintf(keyring_str[0], "%d",
+		tsk->thread_keyring ? tsk->thread_keyring->serial : 0);
+
+	prkey = 0;
+	if (tsk->signal->process_keyring)
+		prkey = tsk->signal->process_keyring->serial;
+
+	sskey = 0;
+	spin_lock_irqsave(&tsk->sighand->siglock, flags);
+	if (tsk->signal->session_keyring)
+		sskey = tsk->signal->session_keyring->serial;
+	spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
+
+
+	if (!sskey)
+		sskey = tsk->user->session_keyring->serial;
+
+	sprintf(keyring_str[1], "%d", prkey);
+	sprintf(keyring_str[2], "%d", sskey);
+
+	/* set up a minimal environment */
+	i = 0;
+	envp[i++] = "HOME=/";
+	envp[i++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
+	envp[i] = NULL;
+
+	/* set up the argument list */
+	i = 0;
+	argv[i++] = "/sbin/request-key";
+	argv[i++] = (char *) op;
+	argv[i++] = key_str;
+	argv[i++] = uid_str;
+	argv[i++] = gid_str;
+	argv[i++] = keyring_str[0];
+	argv[i++] = keyring_str[1];
+	argv[i++] = keyring_str[2];
+	argv[i++] = callout_info[0] ? (char *) callout_info : "-";
+	argv[i] = NULL;
+
+	/* do it */
+	return call_usermodehelper(argv[0], argv, envp, 1);
+
+} /* end call_request_key() */
+
+/*****************************************************************************/
+/*
+ * call out to userspace for the key
+ * - called with the construction sem held, but the sem is dropped here
+ * - we ignore program failure and go on key status instead
+ */
+static struct key *__request_key_construction(struct key_type *type,
+					      const char *description,
+					      const char *callout_info)
+{
+	struct key_construction cons;
+	struct timespec now;
+	struct key *key;
+	int ret, negative;
+
+	/* create a key and add it to the queue */
+	key = key_alloc(type, description,
+			current->fsuid, current->fsgid, KEY_USR_ALL, 0);
+	if (IS_ERR(key))
+		goto alloc_failed;
+
+	write_lock(&key->lock);
+	key->flags |= KEY_FLAG_USER_CONSTRUCT;
+	write_unlock(&key->lock);
+
+	cons.key = key;
+	list_add_tail(&cons.link, &key->user->consq);
+
+	/* we drop the construction sem here on behalf of the caller */
+	up_write(&key_construction_sem);
+
+	/* make the call */
+	ret = call_request_key(key, "create", callout_info);
+	if (ret < 0)
+		goto request_failed;
+
+	/* if the key wasn't instantiated, then we want to give an error */
+	ret = -ENOKEY;
+	if (!(key->flags & KEY_FLAG_INSTANTIATED))
+		goto request_failed;
+
+	down_write(&key_construction_sem);
+	list_del(&cons.link);
+	up_write(&key_construction_sem);
+
+	/* also give an error if the key was negatively instantiated */
+ check_not_negative:
+	if (key->flags & KEY_FLAG_NEGATIVE) {
+		key_put(key);
+		key = ERR_PTR(-ENOKEY);
+	}
+
+ out:
+	return key;
+
+ request_failed:
+	/* it wasn't instantiated
+	 * - remove from construction queue
+	 * - mark the key as dead
+	 */
+	negative = 0;
+	down_write(&key_construction_sem);
+
+	list_del(&cons.link);
+
+	write_lock(&key->lock);
+	key->flags &= ~KEY_FLAG_USER_CONSTRUCT;
+
+	/* check it didn't get instantiated between the check and the down */
+	if (!(key->flags & KEY_FLAG_INSTANTIATED)) {
+		key->flags |= KEY_FLAG_INSTANTIATED | KEY_FLAG_NEGATIVE;
+		negative = 1;
+	}
+
+	write_unlock(&key->lock);
+	up_write(&key_construction_sem);
+
+	if (!negative)
+		goto check_not_negative; /* surprisingly, the key got
+					  * instantiated */
+
+	/* set the timeout and store in the session keyring if we can */
+	now = current_kernel_time();
+	key->expiry = now.tv_sec + key_negative_timeout;
+
+	if (current->signal->session_keyring) {
+		unsigned long flags;
+		struct key *keyring;
+
+		spin_lock_irqsave(&current->sighand->siglock, flags);
+		keyring = current->signal->session_keyring;
+		atomic_inc(&keyring->usage);
+		spin_unlock_irqrestore(&current->sighand->siglock, flags);
+
+		key_link(keyring, key);
+		key_put(keyring);
+	}
+
+	key_put(key);
+
+	/* notify anyone who was waiting */
+	wake_up_all(&request_key_conswq);
+
+	key = ERR_PTR(ret);
+	goto out;
+
+ alloc_failed:
+	up_write(&key_construction_sem);
+	goto out;
+
+} /* end __request_key_construction() */
+
+/*****************************************************************************/
+/*
+ * call out to userspace to request the key
+ * - we check the construction queue first to see if an appropriate key is
+ *   already being constructed by userspace
+ */
+static struct key *request_key_construction(struct key_type *type,
+					    const char *description,
+					    struct key_user *user,
+					    const char *callout_info)
+{
+	struct key_construction *pcons;
+	struct key *key, *ckey;
+
+	DECLARE_WAITQUEUE(myself, current);
+
+	/* see if there's such a key under construction already */
+	down_write(&key_construction_sem);
+
+	list_for_each_entry(pcons, &user->consq, link) {
+		ckey = pcons->key;
+
+		if (ckey->type != type)
+			continue;
+
+		if (type->match(ckey, description))
+			goto found_key_under_construction;
+	}
+
+	/* see about getting userspace to construct the key */
+	key = __request_key_construction(type, description, callout_info);
+ error:
+	return key;
+
+	/* someone else has the same key under construction
+	 * - we want to keep an eye on their key
+	 */
+ found_key_under_construction:
+	atomic_inc(&ckey->usage);
+	up_write(&key_construction_sem);
+
+	/* wait for the key to be completed one way or another */
+	add_wait_queue(&request_key_conswq, &myself);
+
+	for (;;) {
+		set_current_state(TASK_UNINTERRUPTIBLE);
+		if (!(ckey->flags & KEY_FLAG_USER_CONSTRUCT))
+			break;
+		schedule();
+	}
+
+	set_current_state(TASK_RUNNING);
+	remove_wait_queue(&request_key_conswq, &myself);
+
+	/* we'll need to search this process's keyrings to see if the key is
+	 * now there since we can't automatically assume it's also available
+	 * there */
+	key_put(ckey);
+	ckey = NULL;
+
+	key = NULL; /* request a retry */
+	goto error;
+
+} /* end request_key_construction() */
+
+/*****************************************************************************/
+/*
+ * request a key
+ * - search the process's keyrings
+ * - check the list of keys being created or updated
+ * - call out to userspace for a key if requested (supplementary info can be
+ *   passed)
+ */
+struct key *request_key(struct key_type *type,
+			const char *description,
+			const char *callout_info)
+{
+	struct key_user *user;
+	struct key *key;
+
+	/* search all the process keyrings for a key */
+	key = search_process_keyrings_aux(type, description, type->match);
+
+	if (PTR_ERR(key) == -EAGAIN) {
+		/* the search failed, but the keyrings were searchable, so we
+		 * should consult userspace if we can */
+		key = ERR_PTR(-ENOKEY);
+		if (!callout_info)
+			goto error;
+
+		/* - get hold of the user's construction queue */
+		user = key_user_lookup(current->fsuid);
+		if (!user) {
+			key = ERR_PTR(-ENOMEM);
+			goto error;
+		}
+
+		for (;;) {
+			/* ask userspace (returns NULL if it waited on a key
+			 * being constructed) */
+			key = request_key_construction(type, description,
+						       user, callout_info);
+			if (key)
+				break;
+
+			/* someone else made the key we want, so we need to
+			 * search again as it might now be available to us */
+			key = search_process_keyrings_aux(type, description,
+							  type->match);
+			if (PTR_ERR(key) != -EAGAIN)
+				break;
+		}
+
+		key_user_put(user);
+	}
+
+ error:
+	return key;
+
+} /* end request_key() */
+
+EXPORT_SYMBOL(request_key);
+
+/*****************************************************************************/
+/*
+ * validate a key
+ */
+int key_validate(struct key *key)
+{
+	struct timespec now;
+	int ret = 0;
+
+	if (key) {
+		/* check it's still accessible */
+		ret = -EKEYREVOKED;
+		if (key->flags & (KEY_FLAG_REVOKED | KEY_FLAG_DEAD))
+			goto error;
+
+		/* check it hasn't expired */
+		ret = 0;
+		if (key->expiry) {
+			now = current_kernel_time();
+			if (now.tv_sec >= key->expiry)
+				ret = -EKEYEXPIRED;
+		}
+	}
+
+ error:
+	return ret;
+
+} /* end key_validate() */
+
+EXPORT_SYMBOL(key_validate);