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 A4F3E44AB85; Tue, 21 Jul 2026 21:16:10 +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=1784668571; cv=none; b=TOqNltFKuzzjj9IK+CsNqrF40vNl0gqZbXM87+4abtcB6Z4kyN2NQ2pqNtPhS5VJi+1uOuRoqQtH8ZnV99vYmUQ1qzsTmY7QD7XZdE65a3zGm3828Cf+88+1k9bbUFmqzztRaytWZjohE/TLp+KQwcefBSGScHhStCrh30kZnLo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784668571; c=relaxed/simple; bh=XpwmRHL6Fv9IlwpJdmJVMBTS1AZPfswAsM/kNdBIQPA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=MKG8r3Qo8YHNdSRVJnAtQCcYPw4UXxrGtYzonfjQMMtiAuNOZDj9weDxpM7rgVAhmN3m6QM40xOiCnSdYf1Equs3siR4SjlP3/MavPBFBLWyKhM+4wMv+3pBGELl+5/mxHHauj4admRTL9KNLZrduaqyRR+CHacJe3+3Hu5uxps= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=ftyBiuQY; 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="ftyBiuQY" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 163F61F000E9; Tue, 21 Jul 2026 21:16:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784668570; bh=AmuYbcamTaYUhrJa602pzq9/B7veIH1l/tBgqjiOU/Y=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=ftyBiuQY5x5JnFU92GaLD0IiGdUSNZ8eChTVL0gjYRPOpI+k4l2zF1Iwq243HZ7oI 1BBM2USZzkxrY8ABbeQxUz5Me8BXb914hMpQM8znF8Eho//4dIgpueKf70Nos/ipfd Wv8gb+1c3FOIQdWEOiKxhCRx3cg/1KOksXGIEkOM= 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 6.1 0225/1067] NFSv4: include MAY_WRITE in open permission mask for O_TRUNC Date: Tue, 21 Jul 2026 17:13:46 +0200 Message-ID: <20260721152429.632791191@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260721152424.521567757@linuxfoundation.org> References: <20260721152424.521567757@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.1-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 @@ -3237,6 +3237,8 @@ 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;