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authorEric W. Biederman <ebiederm@xmission.com>2016-07-01 20:52:06 +0300
committerEric W. Biederman <ebiederm@xmission.com>2016-07-05 23:11:47 +0300
commit036d523641c66bef713042894a17f4335f199e49 (patch)
treee1d0b786d6da437c10245cd9665b1d3b6b6e246c
parent0bd23d09b874e53bd1a2fe2296030aa2720d7b08 (diff)
downloadlinux-036d523641c66bef713042894a17f4335f199e49.tar.xz
vfs: Don't create inodes with a uid or gid unknown to the vfs
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@canonical.com> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
-rw-r--r--fs/namei.c10
1 files 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);
}