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 9D2543BD643 for ; Wed, 5 Aug 2026 16:43:30 +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=1785948211; cv=none; b=qIkORuNYAMBALO9jTRpbn74tzR64iUs0vLj3uTO2gCx/slb9dPbzRQLKOunJY3k1Pbc6Uuw19hdMTPqCXkWOQA1GLxED6Ah0AMP4kHWkNyE72sZuK+hUkLQpmywUtvIbjEsF0ELgccmIDemwUIjaAPpI//KlPM7+Zci9RQtjsEs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785948211; c=relaxed/simple; bh=HFp9b3fyFj6TUY1liv5fx2joDDSi1B3KK+XEl22WFEo=; h=Message-ID:Date:MIME-Version:Subject:To:References:From: In-Reply-To:Content-Type; b=CgyQWY50mWoG7c8Mrr7Q5HxzlDUMMHPgUYhi7bvr7w5ObV/dwNXw/j1OD/H1vKk27MowRN43mMSI43kIrhWa4XUcAnc83K6dg5rcni4bkmB//Zz8ONIx6ChSpecFNLZfkK5hrC64xYAgzGA4LgiLzK1MCh7smkFYSdUd6ncRLwI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=La7GQSxO; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="La7GQSxO" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EF1D61F00A3A for ; Wed, 5 Aug 2026 16:43:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785948210; bh=A+58uySFn+GP5sG515r9oAkbziyN8Bsi7b7JfCLOueU=; h=Date:Subject:To:References:From:In-Reply-To; b=La7GQSxOEGyTJZ9i6GRC8gJsQXnnlIwXQg2m4oRgEWNGpbGhizBvqY2TfDuy6OuTO CoiNLy9tUL6H8GVcM88C1JnKez3Q6yU3pJfSL4yWuidkmMCMR1alFGjzd/MsaKyh+W hJUslmphUqcr43y+tDbELhb8XExQ0P4pCF6vFRSpxqhiuFhCA0gQVmYmmuCxRpyCZj 126o4hFBXRW0GILnhjc7+cVyo4Qke+e9avG4EJfq3MQL3Jcv+IZCxCd3iCPeq4CvwD GBzQMaQCKFwf5NeO0B0B6ZwKwSbySntuAUS7RGrKW6pnrGAgNhLNkeqlVZX02Eyl3i /a21K4ya6JU+A== Message-ID: Date: Wed, 5 Aug 2026 18:43:29 +0200 Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Beta Subject: Re: [PATCH mptcp-net 2/6] mptcp: pm: userspace: allow announcing ID0 addr Content-Language: fr To: MPTCP Linux References: <20260727-mptcp-pm-userspace-id0-case-v1-0-9877f02a9bae@kernel.org> <20260727-mptcp-pm-userspace-id0-case-v1-2-9877f02a9bae@kernel.org> From: Matthieu Baerts Autocrypt: addr=matttbe@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit Replying to Sashiko's review: >> diff --git a/net/mptcp/pm_userspace.c b/net/mptcp/pm_userspace.c >> index 6e6eeda91ade0..4c96433590e36 100644 >> --- a/net/mptcp/pm_userspace.c >> +++ b/net/mptcp/pm_userspace.c >> @@ -212,12 +212,6 @@ int mptcp_pm_nl_announce_doit(struct sk_buff *skb, struct genl_info *info) >> if (err < 0) >> goto announce_err; >> >> - if (addr_val.addr.id == 0) { >> - NL_SET_ERR_MSG_ATTR(info->extack, addr, "invalid addr id"); >> - err = -EINVAL; >> - goto announce_err; >> - } >> - > > If userspace deletes the initial subflow via MPTCP_PM_CMD_SUBFLOW_DESTROY, > which removes the ID 0 entry from the local address list, can userspace then > announce an arbitrary IP address with ID 0? > > Since the original ID 0 entry would be missing, it seems > mptcp_userspace_pm_append_new_local_addr() wouldn't find an address or ID > match: > > net/mptcp/pm_userspace.c:mptcp_userspace_pm_append_new_local_addr() { > ... > if (!addr_match && !id_match) { > ... > list_add_tail_rcu(&e->list, &msk->pm.userspace_pm_local_addr_list); > msk->pm.local_addr_used++; > ret = e->addr.id; > } > ... > } > > Would this incorrectly append a new entry with ID 0 and an arbitrary IP > address, bypassing the validation mentioned in the commit message? Yes, but the RFC8684 doesn't specify if the ID0 can be replaced by another address, once removed. But it says: "A host wishing to replace an existing Address ID MUST first remove the existing one". In this condition, better to let the responsibility to the userspace daemon. I can add a note in the commit message. > Does allowing ID 0 announcements here also create a state inconsistency when > trying to remove them? > > Looking at mptcp_pm_nl_remove_doit(), there is a hardcoded fast path for ID 0: > > net/mptcp/pm_userspace.c:mptcp_pm_nl_remove_doit() { > ... > if (id_val == 0) { > err = mptcp_userspace_pm_remove_id_zero_address(msk); > goto out; > } > ... > } > > Because mptcp_userspace_pm_remove_id_zero_address() doesn't call > mptcp_pm_announced_remove() and ignores msk->pm.anno_list, would this > leave the announcement un-cancellable and leak the state in anno_list? Removed in the next patch. Cheers, Matt -- Sponsored by the NGI0 Core fund.