It is expected that filesystems can not represent uids and gids from
outside of their user namespace. Keep things simple by not even
trying to create filesystem nodes with non-sense uids and gids.
Acked-by: Seth Forshee <seth.forshee@xxxxxxxxxxxxx>
Signed-off-by: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
---
fs/namei.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/fs/namei.c b/fs/namei.c
index 840201c4c290..629823f19a6a 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -2814,16 +2814,22 @@ static int may_delete(struct inode *dir, struct dentry *victim, bool isdir)
* 1. We can't do it if child already exists (open has special treatment for
* this case, but since we are inlined it's OK)
* 2. We can't do it if dir is read-only (done in permission())
- * 3. We should have write and exec permissions on dir
- * 4. We can't do it if dir is immutable (done in permission())
+ * 3. We can't do it if the fs can't represent the fsuid or fsgid.
+ * 4. We should have write and exec permissions on dir
+ * 5. We can't do it if dir is immutable (done in permission())
*/
static inline int may_create(struct inode *dir, struct dentry *child)
{
+ struct user_namespace *s_user_ns;
audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE);
if (child->d_inode)
return -EEXIST;
if (IS_DEADDIR(dir))
return -ENOENT;
+ s_user_ns = dir->i_sb->s_user_ns;
+ if (!kuid_has_mapping(s_user_ns, current_fsuid()) ||
+ !kgid_has_mapping(s_user_ns, current_fsgid()))
+ return -EOVERFLOW;
return inode_permission(dir, MAY_WRITE | MAY_EXEC);
}
--
2.8.3
--
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