CRED: Wrap task credential accesses in the core kernel

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>
Cc: linux-audit@redhat.com
Cc: containers@lists.linux-foundation.org
Cc: linux-mm@kvack.org
Signed-off-by: James Morris <jmorris@namei.org>

1 files changed, 5 insertions, 4 deletions

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 35eebd5510c2..78f9b310c4f3 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -571,8 +571,8 @@ static struct inode *cgroup_new_inode(mode_t mode, struct super_block *sb)
 
         if (inode) {
                 inode->i_mode = mode;
-                inode->i_uid = current->fsuid;
-                inode->i_gid = current->fsgid;
+                inode->i_uid = current_fsuid();
+                inode->i_gid = current_fsgid();
                 inode->i_blocks = 0;
                 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
                 inode->i_mapping->backing_dev_info = &cgroup_backing_dev_info;
@@ -1279,6 +1279,7 @@ int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk)
 static int attach_task_by_pid(struct cgroup *cgrp, u64 pid)
 {
         struct task_struct *tsk;
+        uid_t euid;
         int ret;
 
         if (pid) {
@@ -1291,8 +1292,8 @@ static int attach_task_by_pid(struct cgroup *cgrp, u64 pid)
                 get_task_struct(tsk);
                 rcu_read_unlock();
 
-                if ((current->euid) && (current->euid != tsk->uid)
-                    && (current->euid != tsk->suid)) {
+                euid = current_euid();
+                if (euid && euid != tsk->uid && euid != tsk->suid) {
                         put_task_struct(tsk);
                         return -EACCES;
                 }