# \[PATCH v2 09/18\] fs: Refuse uid/gid changes which don't map into s\_user\_ns

- From: Seth Forshee \<hidden\>
- Date: 2015-12-07 21:21:18 
- List: linux-raid
- Page: https://ratatoskr.run/linux-raid/2015/12/102590
- Thread: https://ratatoskr.run/linux-bcache/2015/12/102821/t.md

```text
Add checks to inode_change_ok to verify that uid and gid changes
will map into the superblock's user namespace. If they do not
fail with -EOVERFLOW. This cannot be overriden with ATTR_FORCE.

Signed-off-by: Seth Forshee <redacted>
Acked-by: Serge Hallyn <redacted>
---
 fs/attr.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/fs/attr.c b/fs/attr.c
index 6530ced19697..55b46e3aa888 100644
--- a/fs/attr.c
+++ b/fs/attr.c
@@ -42,6 +42,17 @@ int inode_change_ok(const struct inode *inode, struct iattr *attr)
 			return error;
 	}
 
+	/*
+	 * Verify that uid/gid changes are valid in the target namespace
+	 * of the superblock. This cannot be overriden using ATTR_FORCE.
+	 */
+	if (ia_valid & ATTR_UID &&
+	    from_kuid(inode->i_sb->s_user_ns, attr->ia_uid) == (uid_t)-1)
+		return -EOVERFLOW;
+	if (ia_valid & ATTR_GID &&
+	    from_kgid(inode->i_sb->s_user_ns, attr->ia_gid) == (gid_t)-1)
+		return -EOVERFLOW;
+
 	/* If force is set do it anyway. */
 	if (ia_valid & ATTR_FORCE)
 		return 0;
-- 
1.9.1


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```