Uid namespaces will require that when a tasks' permission to an
inode is checked, not just the uid, but also the namespace is
checked.  Since this is a pervasive change, let's start by
introducing a helper without making any semantic changes, so we
can make the semantic change in one place.

Signed-off-by: Serge E. Hallyn <serue@us.ibm.com>

---

 fs/namei.c         |   11 ++++++-----
 include/linux/fs.h |    5 +++++
 2 files changed, 11 insertions(+), 5 deletions(-)

f3afe1adf8ebb6d2e7975dada086df5e9ea36d3c
diff --git a/fs/namei.c b/fs/namei.c
index ede2761..522ec89 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -184,7 +184,7 @@ int generic_permission(struct inode *ino
 {
 	umode_t			mode = inode->i_mode;
 
-	if (current->fsuid == inode->i_uid)
+	if (inode_task_same_uid(inode, current))
 		mode >>= 6;
 	else {
 		if (IS_POSIXACL(inode) && (mode & S_IRWXG) && check_acl) {
@@ -436,7 +436,7 @@ static int exec_permission_lite(struct i
 	if (inode->i_op && inode->i_op->permission)
 		return -EAGAIN;
 
-	if (current->fsuid == inode->i_uid)
+	if (inode_task_same_uid(inode, current))
 		mode >>= 6;
 	else if (in_group_p(inode->i_gid))
 		mode >>= 3;
@@ -1360,9 +1360,9 @@ static inline int check_sticky(struct in
 {
 	if (!(dir->i_mode & S_ISVTX))
 		return 0;
-	if (inode->i_uid == current->fsuid)
+	if (inode_task_same_uid(inode, current))
 		return 0;
-	if (dir->i_uid == current->fsuid)
+	if (inode_task_same_uid(dir, current))
 		return 0;
 	return !capable(CAP_FOWNER);
 }
@@ -1572,7 +1572,8 @@ int may_open(struct nameidata *nd, int a
 
 	/* O_NOATIME can only be set by the owner or superuser */
 	if (flag & O_NOATIME)
-		if (current->fsuid != inode->i_uid && !capable(CAP_FOWNER))
+		if (!inode_task_same_uid(inode, current) &&
+					 !capable(CAP_FOWNER))
 			return -EPERM;
 
 	/*
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 4090d9d..699c7b5 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2157,5 +2157,10 @@ static inline void free_secdata(void *se
 { }
 #endif	/* CONFIG_SECURITY */
 
+static inline int inode_task_same_uid(struct inode *ino,
+		struct task_struct *tsk)
+{
+	return (ino->i_uid == tsk->fsuid);
+}
 #endif /* __KERNEL__ */
 #endif /* _LINUX_FS_H */
-- 
1.1.6
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