From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id CD4AC2FDC53; Thu, 16 Jul 2026 14:15:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784211347; cv=none; b=MRRFJVGXTWfK3gf18exC+CyHGTus9Du1LyDBWxU/Jw8wLN7vt3B972161kUqa6TyrQMt0PboRy4MPzTdghsWgoz32t8Uw6gEtfcsElP91ddlhQfbB2QTlwEuvK/7PcRVFHco5T7XhuhMCEzQ341apaJpyKw0JdPIqZBaJ6ooS9U= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784211347; c=relaxed/simple; bh=u6spkd5JCVGZCWRMuDK8E0p4eZ54jUuECyPFGsrWBwo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=pWeKGGMaTZd2RK6jzo42pYOYfxWVff/o+SjLY7cPsKs/aYJ5tDNgaDv78tcXVPmQSmLjK8Oa60TYcCGiS93+tmdH9z4FuZKGAl+/gGjqnaVokeJXHphej0iLUJrQ3n1XuKuVhqkyHkCHC/wBtHi+G+jKVfQJ2lu//o1v/t6OWkU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=SRRRSbTo; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="SRRRSbTo" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EBD831F000E9; Thu, 16 Jul 2026 14:15:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784211346; bh=5vu238qOtNKPcVYTZDDm3aQc3HKOWLlk+g6k24yuCGg=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=SRRRSbToKZet0EqCHwXTu1ggJGW5kCfYommQ1hzEdXPhepjTVN7bc9K5rv6DOVPRn a3/2tRxaBIxHvie79Rr9KQOAHMS/zKCBxSoHDBQ49JCqB/ZmVhYhDiL6QUstWPL6xc jlYwiKIFGPb6yMkwysdD/HizCJJq6JDa9OiVNrYg= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Trond Myklebust , Benjamin Coddington , Anna Schumaker Subject: [PATCH 6.18 393/480] NFSv4: include MAY_WRITE in open permission mask for O_TRUNC Date: Thu, 16 Jul 2026 15:32:20 +0200 Message-ID: <20260716133053.301692605@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260716133044.672218725@linuxfoundation.org> References: <20260716133044.672218725@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Benjamin Coddington commit 5140f099ecd8a2f2808b7f7b720ee1bad8468974 upstream. POSIX requires write permission to truncate a file, so an open() that specifies O_TRUNC must be authorized for write access regardless of the O_ACCMODE access mode. nfs_open_permission_mask() builds the access mask passed to nfs_may_open(), which is the local authorization gate for OPENs the client serves itself from a cached write delegation via the can_open_delegated() path in nfs4_try_open_cached(). The mask is derived from O_ACCMODE alone, so an open(O_RDONLY | O_TRUNC) against a file the caller cannot write requests only MAY_READ and passes the local check. The OPEN is then satisfied locally and the truncation is issued to the server as a SETATTR(size=0) over the delegation stateid, which the server accepts under standard write-delegation semantics. POSIX requires that this open fail with EACCES. Include MAY_WRITE in the mask whenever O_TRUNC is set so the local check matches the access the server would have enforced. Suggested-by: Trond Myklebust Fixes: af22f94ae02a ("NFSv4: Simplify _nfs4_do_access()") Cc: stable@vger.kernel.org Signed-off-by: Benjamin Coddington Signed-off-by: Anna Schumaker Signed-off-by: Greg Kroah-Hartman --- fs/nfs/dir.c | 2 ++ 1 file changed, 2 insertions(+) --- a/fs/nfs/dir.c +++ b/fs/nfs/dir.c @@ -3302,6 +3302,8 @@ static int nfs_open_permission_mask(int mask |= MAY_READ; if ((openflags & O_ACCMODE) != O_RDONLY) mask |= MAY_WRITE; + if (openflags & O_TRUNC) + mask |= MAY_WRITE; } return mask;