CRED: Wrap task credential accesses in the filesystem subsystem

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: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: James Morris <jmorris@namei.org>

1 files changed, 6 insertions, 4 deletions

diff --git a/fs/namei.c b/fs/namei.c
index 09ce58e49e72..42d7b7606936 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -186,7 +186,7 @@ int generic_permission(struct inode *inode, int mask,
 
         mask &= MAY_READ | MAY_WRITE | MAY_EXEC;
 
-        if (current->fsuid == inode->i_uid)
+        if (current_fsuid() == inode->i_uid)
                 mode >>= 6;
         else {
                 if (IS_POSIXACL(inode) && (mode & S_IRWXG) && check_acl) {
@@ -441,7 +441,7 @@ static int exec_permission_lite(struct inode *inode)
         if (inode->i_op && inode->i_op->permission)
                 return -EAGAIN;
 
-        if (current->fsuid == inode->i_uid)
+        if (current_fsuid() == inode->i_uid)
                 mode >>= 6;
         else if (in_group_p(inode->i_gid))
                 mode >>= 3;
@@ -1334,11 +1334,13 @@ static int user_path_parent(int dfd, const char __user *path,
  */
 static inline int check_sticky(struct inode *dir, struct inode *inode)
 {
+        uid_t fsuid = current_fsuid();
+
         if (!(dir->i_mode & S_ISVTX))
                 return 0;
-        if (inode->i_uid == current->fsuid)
+        if (inode->i_uid == fsuid)
                 return 0;
-        if (dir->i_uid == current->fsuid)
+        if (dir->i_uid == fsuid)
                 return 0;
         return !capable(CAP_FOWNER);
 }