KEYS: Add an RCU payload dereference macro

Add an RCU payload dereference macro as this seems to be a common piece of code
amongst key types that use RCU referenced payloads.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>

4 files changed, 7 insertions, 6 deletions

diff --git a/include/linux/key.h b/include/linux/key.h
index 3db0adce1fda..a6b1edcffc34 100644
--- a/include/linux/key.h
+++ b/include/linux/key.h
@@ -275,6 +275,10 @@ static inline key_serial_t key_serial(struct key *key)
         return key ? key->serial : 0;
 }
 
+#define rcu_dereference_key(KEY)                                        \
+        (rcu_dereference_protected((KEY)->payload.rcudata,              \
+                                   rwsem_is_locked(&((struct key *)(KEY))->sem)))
+
 #ifdef CONFIG_SYSCTL
 extern ctl_table key_sysctls[];
 #endif
diff --git a/security/keys/encrypted.c b/security/keys/encrypted.c
index 9e7e4ce3fae8..69907a58a683 100644
--- a/security/keys/encrypted.c
+++ b/security/keys/encrypted.c
@@ -765,8 +765,7 @@ static long encrypted_read(const struct key *key, char __user *buffer,
         size_t asciiblob_len;
         int ret;
 
-        epayload = rcu_dereference_protected(key->payload.data,
-                                  rwsem_is_locked(&((struct key *)key)->sem));
+        epayload = rcu_dereference_key(key);
 
         /* returns the hex encoded iv, encrypted-data, and hmac as ascii */
         asciiblob_len = epayload->datablob_len + ivsize + 1
diff --git a/security/keys/trusted.c b/security/keys/trusted.c
index 83fc92e297cd..c99b9368368c 100644
--- a/security/keys/trusted.c
+++ b/security/keys/trusted.c
@@ -1076,8 +1076,7 @@ static long trusted_read(const struct key *key, char __user *buffer,
         char *bufp;
         int i;
 
-        p = rcu_dereference_protected(key->payload.data,
-                        rwsem_is_locked(&((struct key *)key)->sem));
+        p = rcu_dereference_key(key);
         if (!p)
                 return -EINVAL;
         if (!buffer || buflen <= 0)
diff --git a/security/keys/user_defined.c b/security/keys/user_defined.c
index 02807fb16340..c6ca8662a468 100644
--- a/security/keys/user_defined.c
+++ b/security/keys/user_defined.c
@@ -184,8 +184,7 @@ long user_read(const struct key *key, char __user *buffer, size_t buflen)
         struct user_key_payload *upayload;
         long ret;
 
-        upayload = rcu_dereference_protected(
-                key->payload.data, rwsem_is_locked(&((struct key *)key)->sem));
+        upayload = rcu_dereference_key(key);
         ret = upayload->datalen;
 
         /* we can return the data as is */