udf: Apply uid/gid mount options also to new inodes & chown

Currently newly created files belong to current user despite
uid=<number> / gid=<number> mount options. This is confusing to users
(as owner of the file will change after remount / eviction from cache)
and also inconsistent with e.g. FAT with the same mount option. So apply
uid=<number> and gid=<number> also to newly created inodes and similarly
as FAT disallow to change owner of the file in this case.

Reported-by: Steve Kenton <skenton@ou.edu>
Reviewed-by: Pali Rohár <pali.rohar@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

2 files changed, 14 insertions, 0 deletions

diff --git a/fs/udf/file.c b/fs/udf/file.c
index 356c2bf148a5..cd31e4f6d6da 100644
--- a/fs/udf/file.c
+++ b/fs/udf/file.c
@@ -257,12 +257,22 @@ const struct file_operations udf_file_operations = {
 static int udf_setattr(struct dentry *dentry, struct iattr *attr)
 {
         struct inode *inode = d_inode(dentry);
+        struct super_block *sb = inode->i_sb;
         int error;
 
         error = setattr_prepare(dentry, attr);
         if (error)
                 return error;
 
+        if ((attr->ia_valid & ATTR_UID) &&
+            UDF_QUERY_FLAG(sb, UDF_FLAG_UID_SET) &&
+            !uid_eq(attr->ia_uid, UDF_SB(sb)->s_uid))
+                return -EPERM;
+        if ((attr->ia_valid & ATTR_GID) &&
+            UDF_QUERY_FLAG(sb, UDF_FLAG_GID_SET) &&
+            !gid_eq(attr->ia_gid, UDF_SB(sb)->s_gid))
+                return -EPERM;
+
         if ((attr->ia_valid & ATTR_SIZE) &&
             attr->ia_size != i_size_read(inode)) {
                 error = udf_setsize(inode, attr->ia_size);
diff --git a/fs/udf/ialloc.c b/fs/udf/ialloc.c
index b6e420c1bfeb..b7a0d4b4bda1 100644
--- a/fs/udf/ialloc.c
+++ b/fs/udf/ialloc.c
@@ -104,6 +104,10 @@ struct inode *udf_new_inode(struct inode *dir, umode_t mode)
         }
 
         inode_init_owner(inode, dir, mode);
+        if (UDF_QUERY_FLAG(sb, UDF_FLAG_UID_SET))
+                inode->i_uid = sbi->s_uid;
+        if (UDF_QUERY_FLAG(sb, UDF_FLAG_GID_SET))
+                inode->i_gid = sbi->s_gid;
 
         iinfo->i_location.logicalBlockNum = block;
         iinfo->i_location.partitionReferenceNum =