keys: allow the callout data to be passed as a blob rather than a string

Allow the callout data to be passed as a blob rather than a string for
internal kernel services that call any request_key_*() interface other than
request_key().  request_key() itself still takes a NUL-terminated string.

The functions that change are:

	request_key_with_auxdata()
	request_key_async()
	request_key_async_with_auxdata()

Signed-off-by: David Howells <dhowells@redhat.com>
Cc: Paul Moore <paul.moore@hp.com>
Cc: Chris Wright <chrisw@sous-sol.org>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Cc: James Morris <jmorris@namei.org>
Cc: Kevin Coffman <kwc@citi.umich.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/key.h b/include/linux/key.h
index a70b8a8..163f864 100644
--- a/include/linux/key.h
+++ b/include/linux/key.h
@@ -208,16 +208,19 @@
 
 extern struct key *request_key_with_auxdata(struct key_type *type,
 					    const char *description,
-					    const char *callout_info,
+					    const void *callout_info,
+					    size_t callout_len,
 					    void *aux);
 
 extern struct key *request_key_async(struct key_type *type,
 				     const char *description,
-				     const char *callout_info);
+				     const void *callout_info,
+				     size_t callout_len);
 
 extern struct key *request_key_async_with_auxdata(struct key_type *type,
 						  const char *description,
-						  const char *callout_info,
+						  const void *callout_info,
+						  size_t callout_len,
 						  void *aux);
 
 extern int wait_for_key_construction(struct key *key, bool intr);