From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 25AC0C282C2 for ; Wed, 13 Feb 2019 18:39:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F0D9D222D6 for ; Wed, 13 Feb 2019 18:39:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1550083199; bh=OBXob9E1le+atK3fC3FjhF6X6K0IhXVElwZw7si7i/A=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=AI1WVS3Aur3ckYlOHwnQfRqKeKHO7oNrG9PyDVUs4mgbPLxF5Z4bx9sIs2xwGXNit BUKEyUWNgOR6dSqjVUa7qY0XkG3hlJ+g/UqaB2aa76kIjW+JeivViwMzAPzkzRzVqS bNtO/IKQSn5p0+WLSWsdfTkNJ+L9CvOsFLnilm7o= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2405318AbfBMSj5 (ORCPT ); Wed, 13 Feb 2019 13:39:57 -0500 Received: from mail.kernel.org ([198.145.29.99]:37946 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2405302AbfBMSjy (ORCPT ); Wed, 13 Feb 2019 13:39:54 -0500 Received: from localhost (5356596B.cm-6-7b.dynamic.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id D7891222D6; Wed, 13 Feb 2019 18:39:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1550083193; bh=OBXob9E1le+atK3fC3FjhF6X6K0IhXVElwZw7si7i/A=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ZponWgQ72/AFuj/ZEOgiMqVUiFlalHwUvGzTkyzJz80S7CLtc3DIZlNhogfjT1B+2 eQ4RNCFdGZ6f/u25++uTaK59QlNymwYPsxDXe3UwLlk/MALnUrrz5ES4Pwdu/91O4y 7ugl6lphS7+Rnr79+GXnCvVlddGKc1oCqO2HRuLA= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Olga Kornievskaia , "J. Bruce Fields" , Salvatore Bonaccorso Subject: [PATCH 4.9 18/24] nfsd4: catch some false session retries Date: Wed, 13 Feb 2019 19:38:15 +0100 Message-Id: <20190213183648.924916825@linuxfoundation.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190213183647.333441569@linuxfoundation.org> References: <20190213183647.333441569@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: J. Bruce Fields commit 53da6a53e1d414e05759fa59b7032ee08f4e22d7 upstream. The spec allows us to return NFS4ERR_SEQ_FALSE_RETRY if we notice that the client is making a call that matches a previous (slot, seqid) pair but that *isn't* actually a replay, because some detail of the call doesn't actually match the previous one. Catching every such case is difficult, but we may as well catch a few easy ones. This also handles the case described in the previous patch, in a different way. The spec does however require us to catch the case where the difference is in the rpc credentials. This prevents somebody from snooping another user's replies by fabricating retries. (But the practical value of the attack is limited by the fact that the replies with the most sensitive data are READ replies, which are not normally cached.) Tested-by: Olga Kornievskaia Signed-off-by: J. Bruce Fields Cc: Salvatore Bonaccorso Signed-off-by: Greg Kroah-Hartman --- fs/nfsd/nfs4state.c | 37 ++++++++++++++++++++++++++++++++++++- fs/nfsd/state.h | 1 + 2 files changed, 37 insertions(+), 1 deletion(-) --- a/fs/nfsd/nfs4state.c +++ b/fs/nfsd/nfs4state.c @@ -1472,8 +1472,10 @@ free_session_slots(struct nfsd4_session { int i; - for (i = 0; i < ses->se_fchannel.maxreqs; i++) + for (i = 0; i < ses->se_fchannel.maxreqs; i++) { + free_svc_cred(&ses->se_slots[i]->sl_cred); kfree(ses->se_slots[i]); + } } /* @@ -2347,6 +2349,8 @@ nfsd4_store_cache_entry(struct nfsd4_com slot->sl_flags |= NFSD4_SLOT_INITIALIZED; slot->sl_opcnt = resp->opcnt; slot->sl_status = resp->cstate.status; + free_svc_cred(&slot->sl_cred); + copy_cred(&slot->sl_cred, &resp->rqstp->rq_cred); if (!nfsd4_cache_this(resp)) { slot->sl_flags &= ~NFSD4_SLOT_CACHED; @@ -3049,6 +3053,34 @@ static bool nfsd4_request_too_big(struct return xb->len > session->se_fchannel.maxreq_sz; } +static bool replay_matches_cache(struct svc_rqst *rqstp, + struct nfsd4_sequence *seq, struct nfsd4_slot *slot) +{ + struct nfsd4_compoundargs *argp = rqstp->rq_argp; + + if ((bool)(slot->sl_flags & NFSD4_SLOT_CACHETHIS) != + (bool)seq->cachethis) + return false; + /* + * If there's an error than the reply can have fewer ops than + * the call. But if we cached a reply with *more* ops than the + * call you're sending us now, then this new call is clearly not + * really a replay of the old one: + */ + if (slot->sl_opcnt < argp->opcnt) + return false; + /* This is the only check explicitly called by spec: */ + if (!same_creds(&rqstp->rq_cred, &slot->sl_cred)) + return false; + /* + * There may be more comparisons we could actually do, but the + * spec doesn't require us to catch every case where the calls + * don't match (that would require caching the call as well as + * the reply), so we don't bother. + */ + return true; +} + __be32 nfsd4_sequence(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate, @@ -3108,6 +3140,9 @@ nfsd4_sequence(struct svc_rqst *rqstp, status = nfserr_seq_misordered; if (!(slot->sl_flags & NFSD4_SLOT_INITIALIZED)) goto out_put_session; + status = nfserr_seq_false_retry; + if (!replay_matches_cache(rqstp, seq, slot)) + goto out_put_session; cstate->slot = slot; cstate->session = session; cstate->clp = clp; --- a/fs/nfsd/state.h +++ b/fs/nfsd/state.h @@ -169,6 +169,7 @@ static inline struct nfs4_delegation *de struct nfsd4_slot { u32 sl_seqid; __be32 sl_status; + struct svc_cred sl_cred; u32 sl_datalen; u16 sl_opcnt; #define NFSD4_SLOT_INUSE (1 << 0)