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 2A05442BE98; Thu, 16 Jul 2026 14:33:02 +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=1784212383; cv=none; b=FVtA0DRlC9azdyuxvydOYV3USWULjGlnLmBz91UViAsY8h5b2pBi3yMPX5Dj+QYJ+RHQ60ZXybdEedYt6pBYi3Pex4GzzNr3Nvgv1a8JrQFINH7LMkwHR+ZW1tbgrLgX6zq/GweRKr+IF4PRft9atlBoDv1vDbeQ0gC5xI/vJ+A= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784212383; c=relaxed/simple; bh=4CNy360/D22Kjxq+8fPJpecjS/tbw/sS1wGZ3jMImjs=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=lriGwZSmXU6a+8vWzOM9MMW4/l/7LbmKN3sWBUG7XHPuxs1g0SJ8X0RCPBrAwEJff+Q6F+URaimesNNkTNURTAYrYVBQ6CvPxGr2czqmoce2lyb5npPI4XQzYanK26C5gWpJvHr6qdWt4RQwsusnf7aT0e+1F8P2QEEVSIea/fI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=UWFaTJUb; 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="UWFaTJUb" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9F8611F000E9; Thu, 16 Jul 2026 14:33:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784212382; bh=s0kpd1AEzm4gZ4ggFpPKa6m+BLBMjKbW/jHXA6YJCQg=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=UWFaTJUbSzSnVYgZYkTw+jb5AfsABYgNBeqVwIKTyEPHLQvPMRI571C0P2ENKXf+2 izdIUWaic8hvi2flG+bEU7GimcKikuEelViLlHJZEAGWOha/Y25LlV849CgOMnfTen wU8OnNzcEi78V7wW4gRzvVb0JsJaYoOwIHFQ1hjU= 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 6.12 306/349] NFSv4: include MAY_WRITE in open permission mask for O_TRUNC Date: Thu, 16 Jul 2026 15:34:00 +0200 Message-ID: <20260716133040.167335284@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260716133033.287196923@linuxfoundation.org> References: <20260716133033.287196923@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 6.12-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 @@ -3318,6 +3318,8 @@ 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;