KEYS: Add a key type op to permit the key description to be vetted
Add a key type operation to permit the key type to vet the description of a new
key that key_alloc() is about to allocate. The operation may reject the
description if it wishes with an error of its choosing. If it does this, the
key will not be allocated.
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Mimi Zohar <zohar@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>
diff --git a/Documentation/keys.txt b/Documentation/keys.txt
index e4dbbdb..cf68d1f 100644
--- a/Documentation/keys.txt
+++ b/Documentation/keys.txt
@@ -1062,6 +1062,13 @@
viable.
+ (*) int (*vet_description)(const char *description);
+
+ This optional method is called to vet a key description. If the key type
+ doesn't approve of the key description, it may return an error, otherwise
+ it should return 0.
+
+
(*) int (*instantiate)(struct key *key, const void *data, size_t datalen);
This method is called to attach a payload to a key during construction.
diff --git a/include/linux/key-type.h b/include/linux/key-type.h
index 65833d4..fc8525e8 100644
--- a/include/linux/key-type.h
+++ b/include/linux/key-type.h
@@ -41,6 +41,9 @@
*/
size_t def_datalen;
+ /* vet a description */
+ int (*vet_description)(const char *description);
+
/* instantiate a key of this type
* - this method should call key_payload_reserve() to determine if the
* user's quota will hold the payload
diff --git a/net/rxrpc/ar-key.c b/net/rxrpc/ar-key.c
index d763793..43ea7de 100644
--- a/net/rxrpc/ar-key.c
+++ b/net/rxrpc/ar-key.c
@@ -25,6 +25,7 @@
#include <keys/user-type.h>
#include "ar-internal.h"
+static int rxrpc_vet_description_s(const char *);
static int rxrpc_instantiate(struct key *, const void *, size_t);
static int rxrpc_instantiate_s(struct key *, const void *, size_t);
static void rxrpc_destroy(struct key *);
@@ -52,6 +53,7 @@
*/
struct key_type key_type_rxrpc_s = {
.name = "rxrpc_s",
+ .vet_description = rxrpc_vet_description_s,
.instantiate = rxrpc_instantiate_s,
.match = user_match,
.destroy = rxrpc_destroy_s,
@@ -59,6 +61,23 @@
};
/*
+ * Vet the description for an RxRPC server key
+ */
+static int rxrpc_vet_description_s(const char *desc)
+{
+ unsigned long num;
+ char *p;
+
+ num = simple_strtoul(desc, &p, 10);
+ if (*p != ':' || num > 65535)
+ return -EINVAL;
+ num = simple_strtoul(p + 1, &p, 10);
+ if (*p || num < 1 || num > 255)
+ return -EINVAL;
+ return 0;
+}
+
+/*
* parse an RxKAD type XDR format token
* - the caller guarantees we have at least 4 words
*/
diff --git a/security/keys/key.c b/security/keys/key.c
index 1c2d43d..8e315ef 100644
--- a/security/keys/key.c
+++ b/security/keys/key.c
@@ -249,6 +249,14 @@
if (!desc || !*desc)
goto error;
+ if (type->vet_description) {
+ ret = type->vet_description(desc);
+ if (ret < 0) {
+ key = ERR_PTR(ret);
+ goto error;
+ }
+ }
+
desclen = strlen(desc) + 1;
quotalen = desclen + type->def_datalen;