fs/vfs/security: pass last path component to LSM on inode creation

SELinux would like to implement a new labeling behavior of newly created
inodes.  We currently label new inodes based on the parent and the creating
process.  This new behavior would also take into account the name of the
new object when deciding the new label.  This is not the (supposed) full path,
just the last component of the path.

This is very useful because creating /etc/shadow is different than creating
/etc/passwd but the kernel hooks are unable to differentiate these
operations.  We currently require that userspace realize it is doing some
difficult operation like that and than userspace jumps through SELinux hoops
to get things set up correctly.  This patch does not implement new
behavior, that is obviously contained in a seperate SELinux patch, but it
does pass the needed name down to the correct LSM hook.  If no such name
exists it is fine to pass NULL.

Signed-off-by: Eric Paris <eparis@redhat.com>

3 files changed, 6 insertions, 5 deletions

diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c
index 1ce240a..49b6cfd 100644
--- a/fs/ext4/ialloc.c
+++ b/fs/ext4/ialloc.c
@@ -1042,7 +1042,7 @@ got:
 	if (err)
 		goto fail_free_drop;
 
-	err = ext4_init_security(handle, inode, dir);
+	err = ext4_init_security(handle, inode, dir, qstr);
 	if (err)
 		goto fail_free_drop;
 
diff --git a/fs/ext4/xattr.h b/fs/ext4/xattr.h
index 1ef1652..25b7387 100644
--- a/fs/ext4/xattr.h
+++ b/fs/ext4/xattr.h
@@ -145,10 +145,10 @@ ext4_expand_extra_isize_ea(struct inode *inode, int new_extra_isize,
 
 #ifdef CONFIG_EXT4_FS_SECURITY
 extern int ext4_init_security(handle_t *handle, struct inode *inode,
-				struct inode *dir);
+			      struct inode *dir, const struct qstr *qstr);
 #else
 static inline int ext4_init_security(handle_t *handle, struct inode *inode,
-				struct inode *dir)
+				     struct inode *dir, const struct qstr *qstr)
 {
 	return 0;
 }
diff --git a/fs/ext4/xattr_security.c b/fs/ext4/xattr_security.c
index 9b21268..007c3bf 100644
--- a/fs/ext4/xattr_security.c
+++ b/fs/ext4/xattr_security.c
@@ -49,14 +49,15 @@ ext4_xattr_security_set(struct dentry *dentry, const char *name,
 }
 
 int
-ext4_init_security(handle_t *handle, struct inode *inode, struct inode *dir)
+ext4_init_security(handle_t *handle, struct inode *inode, struct inode *dir,
+		   const struct qstr *qstr)
 {
 	int err;
 	size_t len;
 	void *value;
 	char *name;
 
-	err = security_inode_init_security(inode, dir, &name, &value, &len);
+	err = security_inode_init_security(inode, dir, qstr, &name, &value, &len);
 	if (err) {
 		if (err == -EOPNOTSUPP)
 			return 0;