add new system file

hc

2024-02-20 102a0743326a03cd1a1202ceda21e175b7d3575c

 kernel/fs/overlayfs/dir.c
..
..
@@ -266,8 +266,7 @@
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 	ovl_dir_modified(dentry->d_parent, false);
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 	ovl_dentry_set_upper_alias(dentry);
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-	ovl_dentry_update_reval(dentry, newdentry,
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-			DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE);
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+	ovl_dentry_init_reval(dentry, newdentry);
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 	if (!hardlink) {
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 		/*
..
..
@@ -586,29 +585,43 @@
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 			goto out_revert_creds;
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 	}
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-	err = -ENOMEM;
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-	override_cred = prepare_creds();
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-	if (override_cred) {
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+	if (!attr->hardlink) {
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+		err = -ENOMEM;
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+		override_cred = prepare_creds();
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+		if (!override_cred)
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+			goto out_revert_creds;
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+		/*
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+		 * In the creation cases(create, mkdir, mknod, symlink),
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+		 * ovl should transfer current's fs{u,g}id to underlying
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+		 * fs. Because underlying fs want to initialize its new
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+		 * inode owner using current's fs{u,g}id. And in this
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+		 * case, the @inode is a new inode that is initialized
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+		 * in inode_init_owner() to current's fs{u,g}id. So use
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+		 * the inode's i_{u,g}id to override the cred's fs{u,g}id.
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+		 *
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+		 * But in the other hardlink case, ovl_link() does not
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+		 * create a new inode, so just use the ovl mounter's
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+		 * fs{u,g}id.
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+		 */
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 		override_cred->fsuid = inode->i_uid;
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 		override_cred->fsgid = inode->i_gid;
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-		if (!attr->hardlink) {
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-			err = security_dentry_create_files_as(dentry,
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-					attr->mode, &dentry->d_name,
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-					old_cred ? old_cred : current_cred(),
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-					override_cred);
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-			if (err) {
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-				put_cred(override_cred);
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-				goto out_revert_creds;
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-			}
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+		err = security_dentry_create_files_as(dentry,
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+				attr->mode, &dentry->d_name,
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+				old_cred ? old_cred : current_cred(),
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+				override_cred);
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+		if (err) {
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+			put_cred(override_cred);
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+			goto out_revert_creds;
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 		}
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 		hold_cred = override_creds(override_cred);
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 		put_cred(override_cred);
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-
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-		if (!ovl_dentry_is_whiteout(dentry))
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-			err = ovl_create_upper(dentry, inode, attr);
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-		else
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-			err = ovl_create_over_whiteout(dentry, inode, attr);
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 	}
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+
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+	if (!ovl_dentry_is_whiteout(dentry))
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+		err = ovl_create_upper(dentry, inode, attr);
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+	else
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+		err = ovl_create_over_whiteout(dentry, inode, attr);
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+
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 out_revert_creds:
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 	ovl_revert_creds(dentry->d_sb, old_cred ?: hold_cred);
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 	if (old_cred && hold_cred)