---

yaml
---
r: 28562
b: refs/heads/master
c: 04c567d
h: refs/heads/master
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: d720024e94de4e8b7f10ee83c532926f3ad5d708
+refs/heads/master: 04c567d9313e4927b9835361d8ac0318ce65af6b

trunk/Documentation/keys.txt

@@ -964,6 +964,16 @@ The structure has a number of fields, some of which are mandatory:
      It is not safe to sleep in this method; the caller may hold spinlocks.
 
 
+ (*) void (*revoke)(struct key *key);
+
+     This method is optional.  It is called to discard part of the payload
+     data upon a key being revoked.  The caller will have the key semaphore
+     write-locked.
+
+     It is safe to sleep in this method, though care should be taken to avoid
+     a deadlock against the key semaphore.
+
+
  (*) void (*destroy)(struct key *key);
 
      This method is optional. It is called to discard the payload data on a key

trunk/include/linux/key.h

@@ -205,6 +205,11 @@ struct key_type {
 	/* match a key against a description */
 	int (*match)(const struct key *key, const void *desc);
 
+	/* clear some of the data from a key on revokation (optional)
+	 * - the key's semaphore will be write-locked by the caller
+	 */
+	void (*revoke)(struct key *key);
+
 	/* clear the data from a key (optional) */
 	void (*destroy)(struct key *key);
 

trunk/security/keys/key.c

@@ -907,6 +907,10 @@ void key_revoke(struct key *key)
 	 * it */
 	down_write(&key->sem);
 	set_bit(KEY_FLAG_REVOKED, &key->flags);
+
+	if (key->type->revoke)
+		key->type->revoke(key);
+
 	up_write(&key->sem);
 
 } /* end key_revoke() */

trunk/security/keys/process_keys.c

@@ -391,6 +391,8 @@ key_ref_t search_process_keyrings(struct key_type *type,
 	struct request_key_auth *rka;
 	key_ref_t key_ref, ret, err;
 
+	might_sleep();
+
 	/* we want to return -EAGAIN or -ENOKEY if any of the keyrings were
 	 * searchable, but we failed to find a key or we found a negative key;
 	 * otherwise we want to return a sample error (probably -EACCES) if
@@ -496,27 +498,35 @@ key_ref_t search_process_keyrings(struct key_type *type,
 	 */
 	if (context->request_key_auth &&
 	    context == current &&
-	    type != &key_type_request_key_auth &&
-	    key_validate(context->request_key_auth) == 0
+	    type != &key_type_request_key_auth
 	    ) {
-		rka = context->request_key_auth->payload.data;
+		/* defend against the auth key being revoked */
+		down_read(&context->request_key_auth->sem);
 
-		key_ref = search_process_keyrings(type, description, match,
-						  rka->context);
+		if (key_validate(context->request_key_auth) == 0) {
+			rka = context->request_key_auth->payload.data;
 
-		if (!IS_ERR(key_ref))
-			goto found;
+			key_ref = search_process_keyrings(type, description,
+							  match, rka->context);
 
-		switch (PTR_ERR(key_ref)) {
-		case -EAGAIN: /* no key */
-			if (ret)
+			up_read(&context->request_key_auth->sem);
+
+			if (!IS_ERR(key_ref))
+				goto found;
+
+			switch (PTR_ERR(key_ref)) {
+			case -EAGAIN: /* no key */
+				if (ret)
+					break;
+			case -ENOKEY: /* negative key */
+				ret = key_ref;
 				break;
-		case -ENOKEY: /* negative key */
-			ret = key_ref;
-			break;
-		default:
-			err = key_ref;
-			break;
+			default:
+				err = key_ref;
+				break;
+			}
+		} else {
+			up_read(&context->request_key_auth->sem);
 		}
 	}
 

trunk/security/keys/request_key_auth.c

@@ -20,6 +20,7 @@
 
 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_revoke(struct key *);
 static void request_key_auth_destroy(struct key *);
 static long request_key_auth_read(const struct key *, char __user *, size_t);
 
@@ -31,6 +32,7 @@ struct key_type key_type_request_key_auth = {
 	.def_datalen	= sizeof(struct request_key_auth),
 	.instantiate	= request_key_auth_instantiate,
 	.describe	= request_key_auth_describe,
+	.revoke		= request_key_auth_revoke,
 	.destroy	= request_key_auth_destroy,
 	.read		= request_key_auth_read,
 };
@@ -91,6 +93,24 @@ static long request_key_auth_read(const struct key *key,
 
 } /* end request_key_auth_read() */
 
+/*****************************************************************************/
+/*
+ * handle revocation of an authorisation token key
+ * - called with the key sem write-locked
+ */
+static void request_key_auth_revoke(struct key *key)
+{
+	struct request_key_auth *rka = key->payload.data;
+
+	kenter("{%d}", key->serial);
+
+	if (rka->context) {
+		put_task_struct(rka->context);
+		rka->context = NULL;
+	}
+
+} /* end request_key_auth_revoke() */
+
 /*****************************************************************************/
 /*
  * destroy an instantiation authorisation token key
@@ -101,6 +121,11 @@ static void request_key_auth_destroy(struct key *key)
 
 	kenter("{%d}", key->serial);
 
+	if (rka->context) {
+		put_task_struct(rka->context);
+		rka->context = NULL;
+	}
+
 	key_put(rka->target_key);
 	kfree(rka);
 
@@ -131,14 +156,26 @@ struct key *request_key_auth_new(struct key *target, const char *callout_info)
 	 * another process */
 	if (current->request_key_auth) {
 		/* it is - use that instantiation context here too */
+		down_read(&current->request_key_auth->sem);
+
+		/* if the auth key has been revoked, then the key we're
+		 * servicing is already instantiated */
+		if (test_bit(KEY_FLAG_REVOKED,
+			     &current->request_key_auth->flags))
+			goto auth_key_revoked;
+
 		irka = current->request_key_auth->payload.data;
 		rka->context = irka->context;
 		rka->pid = irka->pid;
+		get_task_struct(rka->context);
+
+		up_read(&current->request_key_auth->sem);
 	}
 	else {
 		/* it isn't - use this process as the context */
 		rka->context = current;
 		rka->pid = current->pid;
+		get_task_struct(rka->context);
 	}
 
 	rka->target_key = key_get(target);
@@ -161,9 +198,15 @@ struct key *request_key_auth_new(struct key *target, const char *callout_info)
 	if (ret < 0)
 		goto error_inst;
 
-	kleave(" = {%d})", authkey->serial);
+	kleave(" = {%d}", authkey->serial);
 	return authkey;
 
+auth_key_revoked:
+	up_read(&current->request_key_auth->sem);
+	kfree(rka);
+	kleave("= -EKEYREVOKED");
+	return ERR_PTR(-EKEYREVOKED);
+
 error_inst:
 	key_revoke(authkey);
 	key_put(authkey);