1 files changed, 106 insertions, 90 deletions

diff --git a/security/keys/request_key_auth.c b/security/keys/request_key_auth.c
index 85730d5a5a59..8f33cd170e42 100644
--- a/security/keys/request_key_auth.c
+++ b/security/keys/request_key_auth.c
@@ -1,30 +1,28 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 /* Request key authorisation token key definition.
  *
  * 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.
- *
- * See Documentation/security/keys-request-key.txt
+ * See Documentation/security/keys/request-key.rst
  */
 
-#include <linux/module.h>
 #include <linux/sched.h>
 #include <linux/err.h>
 #include <linux/seq_file.h>
 #include <linux/slab.h>
-#include <asm/uaccess.h>
+#include <linux/uaccess.h>
 #include "internal.h"
+#include <keys/request_key_auth-type.h>
 
+static int request_key_auth_preparse(struct key_preparsed_payload *);
+static void request_key_auth_free_preparse(struct key_preparsed_payload *);
 static int request_key_auth_instantiate(struct key *,
 					struct key_preparsed_payload *);
 static void request_key_auth_describe(const struct key *, struct seq_file *);
 static void request_key_auth_revoke(struct key *);
 static void request_key_auth_destroy(struct key *);
-static long request_key_auth_read(const struct key *, char __user *, size_t);
+static long request_key_auth_read(const struct key *, char *, size_t);
 
 /*
  * The request-key authorisation key type definition.
@@ -32,6 +30,8 @@ static long request_key_auth_read(const struct key *, char __user *, size_t);
 struct key_type key_type_request_key_auth = {
 	.name		= ".request_key_auth",
 	.def_datalen	= sizeof(struct request_key_auth),
+	.preparse	= request_key_auth_preparse,
+	.free_preparse	= request_key_auth_free_preparse,
 	.instantiate	= request_key_auth_instantiate,
 	.describe	= request_key_auth_describe,
 	.revoke		= request_key_auth_revoke,
@@ -39,13 +39,22 @@ struct key_type key_type_request_key_auth = {
 	.read		= request_key_auth_read,
 };
 
+static int request_key_auth_preparse(struct key_preparsed_payload *prep)
+{
+	return 0;
+}
+
+static void request_key_auth_free_preparse(struct key_preparsed_payload *prep)
+{
+}
+
 /*
  * Instantiate a request-key authorisation key.
  */
 static int request_key_auth_instantiate(struct key *key,
 					struct key_preparsed_payload *prep)
 {
-	key->payload.data = (struct request_key_auth *)prep->data;
+	rcu_assign_keypointer(key, (struct request_key_auth *)prep->data);
 	return 0;
 }
 
@@ -55,11 +64,14 @@ static int request_key_auth_instantiate(struct key *key,
 static void request_key_auth_describe(const struct key *key,
 				      struct seq_file *m)
 {
-	struct request_key_auth *rka = key->payload.data;
+	struct request_key_auth *rka = dereference_key_rcu(key);
+
+	if (!rka)
+		return;
 
 	seq_puts(m, "key:");
 	seq_puts(m, key->description);
-	if (key_is_instantiated(key))
+	if (key_is_positive(key))
 		seq_printf(m, " pid:%d ci:%zu", rka->pid, rka->callout_len);
 }
 
@@ -68,12 +80,15 @@ static void request_key_auth_describe(const struct key *key,
  * - the key's semaphore is read-locked
  */
 static long request_key_auth_read(const struct key *key,
-				  char __user *buffer, size_t buflen)
+				  char *buffer, size_t buflen)
 {
-	struct request_key_auth *rka = key->payload.data;
+	struct request_key_auth *rka = dereference_key_locked(key);
 	size_t datalen;
 	long ret;
 
+	if (!rka)
+		return -EKEYREVOKED;
+
 	datalen = rka->callout_len;
 	ret = datalen;
 
@@ -82,13 +97,35 @@ static long request_key_auth_read(const struct key *key,
 		if (buflen > datalen)
 			buflen = datalen;
 
-		if (copy_to_user(buffer, rka->callout_info, buflen) != 0)
-			ret = -EFAULT;
+		memcpy(buffer, rka->callout_info, buflen);
 	}
 
 	return ret;
 }
 
+static void free_request_key_auth(struct request_key_auth *rka)
+{
+	if (!rka)
+		return;
+	key_put(rka->target_key);
+	key_put(rka->dest_keyring);
+	if (rka->cred)
+		put_cred(rka->cred);
+	kfree(rka->callout_info);
+	kfree(rka);
+}
+
+/*
+ * Dispose of the request_key_auth record under RCU conditions
+ */
+static void request_key_auth_rcu_disposal(struct rcu_head *rcu)
+{
+	struct request_key_auth *rka =
+		container_of(rcu, struct request_key_auth, rcu);
+
+	free_request_key_auth(rka);
+}
+
 /*
  * Handle revocation of an authorisation token key.
  *
@@ -96,14 +133,11 @@ static long request_key_auth_read(const struct key *key,
  */
 static void request_key_auth_revoke(struct key *key)
 {
-	struct request_key_auth *rka = key->payload.data;
+	struct request_key_auth *rka = dereference_key_locked(key);
 
 	kenter("{%d}", key->serial);
-
-	if (rka->cred) {
-		put_cred(rka->cred);
-		rka->cred = NULL;
-	}
+	rcu_assign_keypointer(key, NULL);
+	call_rcu(&rka->rcu, request_key_auth_rcu_disposal);
 }
 
 /*
@@ -111,48 +145,40 @@ static void request_key_auth_revoke(struct key *key)
  */
 static void request_key_auth_destroy(struct key *key)
 {
-	struct request_key_auth *rka = key->payload.data;
+	struct request_key_auth *rka = rcu_access_pointer(key->payload.rcu_data0);
 
 	kenter("{%d}", key->serial);
-
-	if (rka->cred) {
-		put_cred(rka->cred);
-		rka->cred = NULL;
+	if (rka) {
+		rcu_assign_keypointer(key, NULL);
+		call_rcu(&rka->rcu, request_key_auth_rcu_disposal);
 	}
-
-	key_put(rka->target_key);
-	key_put(rka->dest_keyring);
-	kfree(rka->callout_info);
-	kfree(rka);
 }
 
 /*
  * Create an authorisation token for /sbin/request-key or whoever to gain
  * access to the caller's security data.
  */
-struct key *request_key_auth_new(struct key *target, const void *callout_info,
-				 size_t callout_len, struct key *dest_keyring)
+struct key *request_key_auth_new(struct key *target, const char *op,
+				 const void *callout_info, size_t callout_len,
+				 struct key *dest_keyring)
 {
 	struct request_key_auth *rka, *irka;
-	const struct cred *cred = current->cred;
+	const struct cred *cred = current_cred();
 	struct key *authkey = NULL;
 	char desc[20];
-	int ret;
+	int ret = -ENOMEM;
 
 	kenter("%d,", target->serial);
 
 	/* allocate a auth record */
-	rka = kmalloc(sizeof(*rka), GFP_KERNEL);
-	if (!rka) {
-		kleave(" = -ENOMEM");
-		return ERR_PTR(-ENOMEM);
-	}
-	rka->callout_info = kmalloc(callout_len, GFP_KERNEL);
-	if (!rka->callout_info) {
-		kleave(" = -ENOMEM");
-		kfree(rka);
-		return ERR_PTR(-ENOMEM);
-	}
+	rka = kzalloc(sizeof(*rka), GFP_KERNEL);
+	if (!rka)
+		goto error;
+	rka->callout_info = kmemdup(callout_info, callout_len, GFP_KERNEL);
+	if (!rka->callout_info)
+		goto error_free_rka;
+	rka->callout_len = callout_len;
+	strscpy(rka->op, op, sizeof(rka->op));
 
 	/* see if the calling process is already servicing the key request of
 	 * another process */
@@ -162,10 +188,14 @@ struct key *request_key_auth_new(struct key *target, const void *callout_info,
 
 		/* if the auth key has been revoked, then the key we're
 		 * servicing is already instantiated */
-		if (test_bit(KEY_FLAG_REVOKED, &cred->request_key_auth->flags))
-			goto auth_key_revoked;
-
-		irka = cred->request_key_auth->payload.data;
+		if (test_bit(KEY_FLAG_REVOKED,
+			     &cred->request_key_auth->flags)) {
+			up_read(&cred->request_key_auth->sem);
+			ret = -EKEYREVOKED;
+			goto error_free_rka;
+		}
+
+		irka = cred->request_key_auth->payload.data[0];
 		rka->cred = get_cred(irka->cred);
 		rka->pid = irka->pid;
 
@@ -179,75 +209,61 @@ struct key *request_key_auth_new(struct key *target, const void *callout_info,
 
 	rka->target_key = key_get(target);
 	rka->dest_keyring = key_get(dest_keyring);
-	memcpy(rka->callout_info, callout_info, callout_len);
-	rka->callout_len = callout_len;
 
 	/* allocate the auth key */
 	sprintf(desc, "%x", target->serial);
 
 	authkey = key_alloc(&key_type_request_key_auth, desc,
 			    cred->fsuid, cred->fsgid, cred,
-			    KEY_POS_VIEW | KEY_POS_READ | KEY_POS_SEARCH |
-			    KEY_USR_VIEW, KEY_ALLOC_NOT_IN_QUOTA);
+			    KEY_POS_VIEW | KEY_POS_READ | KEY_POS_SEARCH | KEY_POS_LINK |
+			    KEY_USR_VIEW, KEY_ALLOC_NOT_IN_QUOTA, NULL);
 	if (IS_ERR(authkey)) {
 		ret = PTR_ERR(authkey);
-		goto error_alloc;
+		goto error_free_rka;
 	}
 
 	/* construct the auth key */
 	ret = key_instantiate_and_link(authkey, rka, 0, NULL, NULL);
 	if (ret < 0)
-		goto error_inst;
+		goto error_put_authkey;
 
-	kleave(" = {%d,%d}", authkey->serial, atomic_read(&authkey->usage));
+	kleave(" = {%d,%d}", authkey->serial, refcount_read(&authkey->usage));
 	return authkey;
 
-auth_key_revoked:
-	up_read(&cred->request_key_auth->sem);
-	kfree(rka->callout_info);
-	kfree(rka);
-	kleave("= -EKEYREVOKED");
-	return ERR_PTR(-EKEYREVOKED);
-
-error_inst:
-	key_revoke(authkey);
+error_put_authkey:
 	key_put(authkey);
-error_alloc:
-	key_put(rka->target_key);
-	key_put(rka->dest_keyring);
-	kfree(rka->callout_info);
-	kfree(rka);
+error_free_rka:
+	free_request_key_auth(rka);
+error:
 	kleave("= %d", ret);
 	return ERR_PTR(ret);
 }
 
 /*
- * See if an authorisation key is associated with a particular key.
- */
-static int key_get_instantiation_authkey_match(const struct key *key,
-					       const void *_id)
-{
-	struct request_key_auth *rka = key->payload.data;
-	key_serial_t id = (key_serial_t)(unsigned long) _id;
-
-	return rka->target_key->serial == id;
-}
-
-/*
  * Search the current process's keyrings for the authorisation key for
  * instantiation of a key.
  */
 struct key *key_get_instantiation_authkey(key_serial_t target_id)
 {
-	const struct cred *cred = current_cred();
+	char description[16];
+	struct keyring_search_context ctx = {
+		.index_key.type		= &key_type_request_key_auth,
+		.index_key.description	= description,
+		.cred			= current_cred(),
+		.match_data.cmp		= key_default_cmp,
+		.match_data.raw_data	= description,
+		.match_data.lookup_type	= KEYRING_SEARCH_LOOKUP_DIRECT,
+		.flags			= (KEYRING_SEARCH_DO_STATE_CHECK |
+					   KEYRING_SEARCH_RECURSE),
+	};
 	struct key *authkey;
 	key_ref_t authkey_ref;
 
-	authkey_ref = search_process_keyrings(
-		&key_type_request_key_auth,
-		(void *) (unsigned long) target_id,
-		key_get_instantiation_authkey_match,
-		cred);
+	ctx.index_key.desc_len = sprintf(description, "%x", target_id);
+
+	rcu_read_lock();
+	authkey_ref = search_process_keyrings_rcu(&ctx);
+	rcu_read_unlock();
 
 	if (IS_ERR(authkey_ref)) {
 		authkey = ERR_CAST(authkey_ref);