From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 6BE5370814; Tue, 28 Oct 2025 20:07:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761682076; cv=none; b=MreTTeIfLk/WSrRRfa4aVilfNZVQQs0fa0gpho6+xlboYJ6LNZFe9dyW8Fsm7F/8YWkqBg290wHWyjq6z+3R65UiGXzYimggFp/DFJEPTEeKhftIbWZh3wYX6OCVukMGRHR7yF3Fz6ODv8mTV0D5BDAKd3ZbA+EZyU/W63MjhhY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761682076; c=relaxed/simple; bh=lqhcGj8AvOs5ztyB9VxiBJaNBn39P9EjaFW2eYVQxlE=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=aJkJEtzxq+R2EHF2P5UJXkg0Yp2pZBp8blHv+ahyKRiJestyPhfGgOGxViuiHC4iyoUGp+2RnVdvwlF4VivEUKbNZNsVeNZKpsX3CZ4hdwbDFPnslHXcgeyE15/UY6hXNswHQFWTDViIZ0NltqZJUXwhdlIQJfSSi70voSNLhrw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=H0ADMY+N; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="H0ADMY+N" Received: by smtp.kernel.org (Postfix) with ESMTPSA id ED442C4CEE7; Tue, 28 Oct 2025 20:07:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1761682076; bh=lqhcGj8AvOs5ztyB9VxiBJaNBn39P9EjaFW2eYVQxlE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=H0ADMY+NtLDcGkjx+pJRYYTdyo7ne4j7NrFRzVnMLqWvtYAfIOitYnbolEvC3cT3B 78XwjyJRUL+fwPcfS4UTj9jN7NaC2fH0Y4vsEtimfWgY9QfpYGAp1uSmJOl/0IGG5g 7MvPrXz0+1TTviGh/9MmQlBOAzrLwk8KxtdcfnI0Jp7fgkwq1fw+YQdhZIdlxQ43oV jctJQ5trvuTDmJgPz9Jdai6smQHtEw6gUhO3OwGFUnNYt3QRASdbadfKtu4vu9nlWW eXCBAhEBsyQONBuv78Dz54/rLraHfo8P83tCnnmZchlrMSL+YprrV9TF9z64e8odfT XFV++yKc6kpfA== Date: Tue, 28 Oct 2025 13:07:55 -0700 From: "Darrick J. Wong" To: Brajesh Patil Cc: miklos@szeredi.hu, stefanha@redhat.com, vgoyal@redhat.com, eperezma@redhat.com, virtualization@lists.linux.dev, virtio-fs@lists.linux.dev, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, skhan@linuxfoundation.org, linux-kernel-mentees@lists.linux.dev, david.hunter.linux@gmail.com, khalid@kernel.org Subject: Re: [PATCH] fuse: virtio_fs: add checks for FUSE protocol compliance Message-ID: <20251028200755.GJ6174@frogsfrogsfrogs> References: <20251028200311.40372-1-brajeshpatil11@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel-mentees@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251028200311.40372-1-brajeshpatil11@gmail.com> On Wed, Oct 29, 2025 at 01:33:11AM +0530, Brajesh Patil wrote: > Add validation in virtio-fs to ensure the server follows the FUSE > protocol for response headers, addressing the existing TODO for > verifying protocol compliance. > > Add checks for fuse_out_header to verify: > - oh->unique matches req->in.h.unique > - FUSE_INT_REQ_BIT is not set > - error codes are valid > - oh->len does not exceed the expected size > > Signed-off-by: Brajesh Patil > --- > fs/fuse/virtio_fs.c | 30 +++++++++++++++++++++++++----- > 1 file changed, 25 insertions(+), 5 deletions(-) > > diff --git a/fs/fuse/virtio_fs.c b/fs/fuse/virtio_fs.c > index 6bc7c97b017d..52e8338bf436 100644 > --- a/fs/fuse/virtio_fs.c > +++ b/fs/fuse/virtio_fs.c > @@ -764,14 +764,34 @@ static void virtio_fs_request_complete(struct fuse_req *req, > { > struct fuse_args *args; > struct fuse_args_pages *ap; > - unsigned int len, i, thislen; > + struct fuse_out_header *oh; > + unsigned int len, i, thislen, expected_len = 0; > struct folio *folio; > > - /* > - * TODO verify that server properly follows FUSE protocol > - * (oh.uniq, oh.len) > - */ > + oh = &req->out.h; > + > + if (oh->unique == 0) > + pr_warn_once("notify through fuse-virtio-fs not supported"); > + > + if ((oh->unique & ~FUSE_INT_REQ_BIT) != req->in.h.unique) > + pr_warn_ratelimited("virtio-fs: unique mismatch, expected: %llu got %llu\n", > + req->in.h.unique, oh->unique & ~FUSE_INT_REQ_BIT); Er... shouldn't these be rejecting the response somehow? Instead of warning that something's amiss but continuing with known bad data? --D > + > + WARN_ON_ONCE(oh->unique & FUSE_INT_REQ_BIT); > + > + if (oh->error <= -ERESTARTSYS || oh->error > 0) > + pr_warn_ratelimited("virtio-fs: invalid error code from server: %d\n", > + oh->error); > + > args = req->args; > + > + for (i = 0; i < args->out_numargs; i++) > + expected_len += args->out_args[i].size; > + > + if (oh->len > sizeof(*oh) + expected_len) > + pr_warn("FUSE reply too long! got=%u expected<=%u\n", > + oh->len, (unsigned int)(sizeof(*oh) + expected_len)); > + > copy_args_from_argbuf(args, req); > > if (args->out_pages && args->page_zeroing) { > -- > 2.43.0 > >