CRED: Wrap task credential accesses in the block loopback driver

Wrap access to task credentials so that they can be separated more easily from
the task_struct during the introduction of COW creds.

Change most current->(|e|s|fs)[ug]id to current_(|e|s|fs)[ug]id().

Change some task->e?[ug]id to task_e?[ug]id().  In some places it makes more
sense to use RCU directly rather than a convenient wrapper; these will be
addressed by later patches.

Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: James Morris <jmorris@namei.org>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: James Morris <jmorris@namei.org>

1 files changed, 4 insertions, 2 deletions

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 5c4ee70d5cf3..fb06ed659212 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -936,8 +936,10 @@ loop_set_status(struct loop_device *lo, const struct loop_info64 *info)
 {
         int err;
         struct loop_func_table *xfer;
+        uid_t uid = current_uid();
 
-        if (lo->lo_encrypt_key_size && lo->lo_key_owner != current->uid &&
+        if (lo->lo_encrypt_key_size &&
+            lo->lo_key_owner != uid &&
             !capable(CAP_SYS_ADMIN))
                 return -EPERM;
         if (lo->lo_state != Lo_bound)
@@ -992,7 +994,7 @@ loop_set_status(struct loop_device *lo, const struct loop_info64 *info)
         if (info->lo_encrypt_key_size) {
                 memcpy(lo->lo_encrypt_key, info->lo_encrypt_key,
                        info->lo_encrypt_key_size);
-                lo->lo_key_owner = current->uid;
+                lo->lo_key_owner = uid;
         }       
 
         return 0;