From patchwork Tue Apr 6 12:21:13 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Pablo Neira Ayuso X-Patchwork-Id: 417331 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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 D30A7C43460 for ; Tue, 6 Apr 2021 12:22:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B2FAE613CA for ; Tue, 6 Apr 2021 12:22:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344116AbhDFMW3 (ORCPT ); Tue, 6 Apr 2021 08:22:29 -0400 Received: from mail.netfilter.org ([217.70.188.207]:34438 "EHLO mail.netfilter.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1343969AbhDFMWC (ORCPT ); Tue, 6 Apr 2021 08:22:02 -0400 Received: from localhost.localdomain (unknown [90.77.255.23]) by mail.netfilter.org (Postfix) with ESMTPSA id F2DA563E5F; Tue, 6 Apr 2021 14:21:28 +0200 (CEST) From: Pablo Neira Ayuso To: netfilter-devel@vger.kernel.org Cc: davem@davemloft.net, netdev@vger.kernel.org, kuba@kernel.org Subject: [PATCH net-next 08/28] netfilter: nft_log: perform module load from nf_tables Date: Tue, 6 Apr 2021 14:21:13 +0200 Message-Id: <20210406122133.1644-9-pablo@netfilter.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210406122133.1644-1-pablo@netfilter.org> References: <20210406122133.1644-1-pablo@netfilter.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Florian Westphal modprobe calls from the nf_logger_find_get() API causes deadlock in very special cases because they occur with the nf_tables transaction mutex held. In the specific case of nf_log, deadlock is via: A nf_tables -> transaction mutex -> nft_log -> modprobe -> nf_log_syslog \ -> pernet_ops rwsem -> wait for C B netlink event -> rtnl_mutex -> nf_tables transaction mutex -> wait for A C close() -> ip6mr_sk_done -> rtnl_mutex -> wait for B Earlier patch added NFLOG/xt_LOG module softdeps to avoid the need to load the backend module during a transaction. For nft_log we would have to add a softdep for both nfnetlink_log or nf_log_syslog, since we do not know in advance which of the two backends are going to be configured. This defers the modprobe op until after the transaction mutex is released. Tested-by: Phil Sutter Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso --- include/net/netfilter/nf_tables.h | 5 +++++ net/netfilter/nf_log.c | 3 --- net/netfilter/nf_tables_api.c | 5 +++-- net/netfilter/nft_log.c | 20 +++++++++++++++++++- 4 files changed, 27 insertions(+), 6 deletions(-) diff --git a/include/net/netfilter/nf_tables.h b/include/net/netfilter/nf_tables.h index 0cef5ad9768a..8fefa112ae89 100644 --- a/include/net/netfilter/nf_tables.h +++ b/include/net/netfilter/nf_tables.h @@ -1562,4 +1562,9 @@ void nf_tables_trans_destroy_flush_work(void); int nf_msecs_to_jiffies64(const struct nlattr *nla, u64 *result); __be64 nf_jiffies64_to_msecs(u64 input); +#ifdef CONFIG_MODULES +__printf(2, 3) int nft_request_module(struct net *net, const char *fmt, ...); +#else +static inline int nft_request_module(struct net *net, const char *fmt, ...) { return -ENOENT; } +#endif #endif /* _NET_NF_TABLES_H */ diff --git a/net/netfilter/nf_log.c b/net/netfilter/nf_log.c index eaa8181f5ef7..edee7fa944c1 100644 --- a/net/netfilter/nf_log.c +++ b/net/netfilter/nf_log.c @@ -170,9 +170,6 @@ int nf_logger_find_get(int pf, enum nf_log_type type) return 0; } - if (rcu_access_pointer(loggers[pf][type]) == NULL) - request_module("nf-logger-%u-%u", pf, type); - rcu_read_lock(); logger = rcu_dereference(loggers[pf][type]); if (logger == NULL) diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c index fc2526b8bd55..c09b67f2f64c 100644 --- a/net/netfilter/nf_tables_api.c +++ b/net/netfilter/nf_tables_api.c @@ -586,8 +586,8 @@ struct nft_module_request { }; #ifdef CONFIG_MODULES -static __printf(2, 3) int nft_request_module(struct net *net, const char *fmt, - ...) +__printf(2, 3) int nft_request_module(struct net *net, const char *fmt, + ...) { char module_name[MODULE_NAME_LEN]; struct nft_module_request *req; @@ -620,6 +620,7 @@ static __printf(2, 3) int nft_request_module(struct net *net, const char *fmt, return -EAGAIN; } +EXPORT_SYMBOL_GPL(nft_request_module); #endif static void lockdep_nfnl_nft_mutex_not_held(void) diff --git a/net/netfilter/nft_log.c b/net/netfilter/nft_log.c index a06a46b039c5..54f6c2035e84 100644 --- a/net/netfilter/nft_log.c +++ b/net/netfilter/nft_log.c @@ -128,6 +128,20 @@ static const struct nla_policy nft_log_policy[NFTA_LOG_MAX + 1] = { [NFTA_LOG_FLAGS] = { .type = NLA_U32 }, }; +static int nft_log_modprobe(struct net *net, enum nf_log_type t) +{ + switch (t) { + case NF_LOG_TYPE_LOG: + return nft_request_module(net, "%s", "nf_log_syslog"); + case NF_LOG_TYPE_ULOG: + return nft_request_module(net, "%s", "nfnetlink_log"); + case NF_LOG_TYPE_MAX: + break; + } + + return -ENOENT; +} + static int nft_log_init(const struct nft_ctx *ctx, const struct nft_expr *expr, const struct nlattr * const tb[]) @@ -197,8 +211,12 @@ static int nft_log_init(const struct nft_ctx *ctx, return 0; err = nf_logger_find_get(ctx->family, li->type); - if (err < 0) + if (err < 0) { + if (nft_log_modprobe(ctx->net, li->type) == -EAGAIN) + err = -EAGAIN; + goto err1; + } return 0;