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 3971E477E58; Thu, 20 Aug 2026 16:26:14 +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=1787243177; cv=none; b=G5vBMnUur7UU2akbf+4Fb3//OFXawvX5Hhdn5sBDrZ/16tSnf1JZxdUr049MxRYnCU7Olqf6SX825FMqnXIgAzp06ii1xWGme6SBNXJB36qdp/BVz3TOwR832s6px0/EwpclPeQV/OcfO68LnYieJQ+DyJgC0fTJo/JG2WBhKBQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787243177; c=relaxed/simple; bh=poqJimMhFAJo+TXbOKDw8ej+yLbO5Q+GyPURW4oXyxA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=pDx6NN3RiaWlwKNFVKUWO0XOsmyfUVJvskNk865dNz3Cp75ODZqr9N81kwk6FuxYXJp91yb8xu4und1EdzSIjpH90FT6I+wi9z+9GUOXdluHKlEh3eX51Yz+Kv/0Bhs/VxP5KLZdZ0AWLZoy17CZnMYu5hVH1BEEBXRBsykOCl8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=bG0NmpIz; 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="bG0NmpIz" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3E1611F000E9; Thu, 20 Aug 2026 16:26:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1787243174; bh=gYGb+zRq7EQ1eIGx0RFm9idqcbR+F+IIqjWpqm2OO7w=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=bG0NmpIzLXiSrIvZp2JcAjW5Pf4UhipsOHWVNxccFl7f1joGu3OKRjIrkY2rQLHS7 bd/Z+2zp8kbANmCFu44RsqvPfJTzj08f6GZKZS6orTuSwYLPD7+5h1Qqv/dU7IIZru /LCefA2uj+A+ED03ms958oxBY2XpyVvRMgWA4pME= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Vega , Zihan Xi , Florian Westphal , Pablo Neira Ayuso , Sasha Levin Subject: [PATCH 6.1 276/303] netfilter: nf_conntrack: defer invalid log until after unlock Date: Thu, 20 Aug 2026 16:56:52 +0200 Message-ID: <20260820145301.763799745@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260820145253.200766705@linuxfoundation.org> References: <20260820145253.200766705@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev 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: Zihan Xi [ Upstream commit 2d19b95c9723001f214f7a47d67b09f46238f200 ] TCP and SCTP conntrack paths can emit invalid-packet logs while ct->lock is still held. When invalid logging is routed to nfnetlink_log and conntrack export is enabled, the log path can re-enter conntrack netlink glue and dump the same conntrack again. Protocol attribute dumping may take ct->lock, so logging while holding that lock can deadlock. Defer the TCP invalid logs by storing only the minimal log context while ct->lock is held and emitting the log after unlocking. Also make the TCP timeout-lowering invalid path return whether a log is needed, then emit that log after unlocking. Do the same for the SCTP invalid state-transition log that can be reached while ct->lock is held. Add a lockdep assertion to nf_ct_l4proto_log_invalid() so future callers that log invalid conntracks while holding ct->lock are caught outside TCP and SCTP as well. Fixes: 628d694344a0 ("netfilter: conntrack: reduce timeout when receiving out-of-window fin or rst") Fixes: d9a6f0d0df18 ("netfilter: conntrack: prepare tcp_in_window for ternary return value") Fixes: f71cb8f45d09 ("netfilter: conntrack: sctp: use nf log infrastructure for invalid packets") Cc: stable@vger.kernel.org Reported-by: Vega Assisted-by: Codex:gpt-5.4 Signed-off-by: Zihan Xi Reviewed-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- net/netfilter/nf_conntrack_proto.c | 6 + net/netfilter/nf_conntrack_proto_sctp.c | 12 +- net/netfilter/nf_conntrack_proto_tcp.c | 132 +++++++++++++++++++++----------- 3 files changed, 102 insertions(+), 48 deletions(-) --- a/net/netfilter/nf_conntrack_proto.c +++ b/net/netfilter/nf_conntrack_proto.c @@ -79,6 +79,12 @@ void nf_ct_l4proto_log_invalid(const str struct net *net; va_list args; + /* nfnetlink_log may re-enter conntrack attribute dumping and try to + * take ct->lock again via helpers such as tcp_to_nlattr(), so invalid + * conntrack logs must only be emitted after dropping ct->lock. + */ + lockdep_assert_not_held(&ct->lock); + net = nf_ct_net(ct); if (likely(net->ct.sysctl_log_invalid == 0)) return; --- a/net/netfilter/nf_conntrack_proto_sctp.c +++ b/net/netfilter/nf_conntrack_proto_sctp.c @@ -340,10 +340,12 @@ int nf_conntrack_sctp_packet(struct nf_c struct sctphdr _sctph; const struct sctp_chunkhdr *sch; struct sctp_chunkhdr _sch; + bool log_invalid = false; u_int32_t offset, count; unsigned int *timeouts; unsigned long map[256 / sizeof(unsigned long)] = { 0 }; bool ignore = false; + u8 invalid_type = 0; if (sctp_error(skb, dataoff, state)) return -NF_ACCEPT; @@ -455,10 +457,8 @@ int nf_conntrack_sctp_packet(struct nf_c /* Invalid */ if (new_state == SCTP_CONNTRACK_MAX) { - nf_ct_l4proto_log_invalid(skb, ct, state, - "Invalid, old_state %d, dir %d, type %d", - old_state, dir, sch->type); - + log_invalid = true; + invalid_type = sch->type; goto out_unlock; } @@ -533,6 +533,10 @@ int nf_conntrack_sctp_packet(struct nf_c out_unlock: spin_unlock_bh(&ct->lock); + if (log_invalid) + nf_ct_l4proto_log_invalid(skb, ct, state, + "Invalid, old_state %d, dir %d, type %d", + old_state, dir, invalid_type); out: return -NF_ACCEPT; } --- a/net/netfilter/nf_conntrack_proto_tcp.c +++ b/net/netfilter/nf_conntrack_proto_tcp.c @@ -480,37 +480,81 @@ static void tcp_init_sender(struct ip_ct } } -__printf(6, 7) -static enum nf_ct_tcp_action nf_tcp_log_invalid(const struct sk_buff *skb, - const struct nf_conn *ct, - const struct nf_hook_state *state, - const struct ip_ct_tcp_state *sender, - enum nf_ct_tcp_action ret, - const char *fmt, ...) +enum nf_tcp_invalid_log_type { + NF_TCP_LOG_NONE, + NF_TCP_LOG_OVERSHOT, + NF_TCP_LOG_SEQ_OVER, + NF_TCP_LOG_ACK_OVER, + NF_TCP_LOG_SEQ_UNDER, + NF_TCP_LOG_ACK_UNDER, +}; + +struct nf_tcp_invalid_log { + enum nf_tcp_invalid_log_type type; + u32 value; +}; + +static enum nf_ct_tcp_action +nf_tcp_store_invalid(const struct nf_conn *ct, + const struct ip_ct_tcp_state *sender, + struct nf_tcp_invalid_log *log, + enum nf_ct_tcp_action ret, + enum nf_tcp_invalid_log_type type, + u32 value) { const struct nf_tcp_net *tn = nf_tcp_pernet(nf_ct_net(ct)); - struct va_format vaf; - va_list args; bool be_liberal; be_liberal = sender->flags & IP_CT_TCP_FLAG_BE_LIBERAL || tn->tcp_be_liberal; if (be_liberal) return NFCT_TCP_ACCEPT; - va_start(args, fmt); - vaf.fmt = fmt; - vaf.va = &args; - nf_ct_l4proto_log_invalid(skb, ct, state, "%pV", &vaf); - va_end(args); - + log->type = type; + log->value = value; return ret; } +static void nf_tcp_log_invalid(const struct sk_buff *skb, + const struct nf_conn *ct, + const struct nf_hook_state *state, + const struct nf_tcp_invalid_log *log) +{ + switch (log->type) { + case NF_TCP_LOG_OVERSHOT: + nf_ct_l4proto_log_invalid(skb, ct, state, + "%u bytes more than expected", + log->value); + break; + case NF_TCP_LOG_SEQ_OVER: + nf_ct_l4proto_log_invalid(skb, ct, state, + "SEQ is over upper bound %u (over the window of the receiver)", + log->value); + break; + case NF_TCP_LOG_ACK_OVER: + nf_ct_l4proto_log_invalid(skb, ct, state, + "ACK is over upper bound %u (ACKed data not seen yet)", + log->value); + break; + case NF_TCP_LOG_SEQ_UNDER: + nf_ct_l4proto_log_invalid(skb, ct, state, + "SEQ is under lower bound %u (already ACKed data retransmitted)", + log->value); + break; + case NF_TCP_LOG_ACK_UNDER: + nf_ct_l4proto_log_invalid(skb, ct, state, + "ignored ACK under lower bound %u (possible overly delayed)", + log->value); + break; + case NF_TCP_LOG_NONE: + break; + } +} + static enum nf_ct_tcp_action tcp_in_window(struct nf_conn *ct, enum ip_conntrack_dir dir, unsigned int index, const struct sk_buff *skb, unsigned int dataoff, const struct tcphdr *tcph, - const struct nf_hook_state *hook_state) + struct nf_tcp_invalid_log *log) { struct ip_ct_tcp *state = &ct->proto.tcp; struct ip_ct_tcp_state *sender = &state->seen[dir]; @@ -640,31 +684,29 @@ tcp_in_window(struct nf_conn *ct, enum i sender->td_end = end; sender->flags |= IP_CT_TCP_FLAG_DATA_UNACKNOWLEDGED; - return nf_tcp_log_invalid(skb, ct, hook_state, sender, NFCT_TCP_IGNORE, - "%u bytes more than expected", overshot); + return nf_tcp_store_invalid(ct, sender, log, NFCT_TCP_IGNORE, + NF_TCP_LOG_OVERSHOT, overshot); } - return nf_tcp_log_invalid(skb, ct, hook_state, sender, NFCT_TCP_INVALID, - "SEQ is over upper bound %u (over the window of the receiver)", - sender->td_maxend + 1); + return nf_tcp_store_invalid(ct, sender, log, NFCT_TCP_INVALID, + NF_TCP_LOG_SEQ_OVER, sender->td_maxend + 1); } if (!before(sack, receiver->td_end + 1)) - return nf_tcp_log_invalid(skb, ct, hook_state, sender, NFCT_TCP_INVALID, - "ACK is over upper bound %u (ACKed data not seen yet)", - receiver->td_end + 1); + return nf_tcp_store_invalid(ct, sender, log, NFCT_TCP_INVALID, + NF_TCP_LOG_ACK_OVER, receiver->td_end + 1); /* Is the ending sequence in the receive window (if available)? */ in_recv_win = !receiver->td_maxwin || after(end, sender->td_end - receiver->td_maxwin - 1); if (!in_recv_win) - return nf_tcp_log_invalid(skb, ct, hook_state, sender, NFCT_TCP_IGNORE, - "SEQ is under lower bound %u (already ACKed data retransmitted)", - sender->td_end - receiver->td_maxwin - 1); + return nf_tcp_store_invalid(ct, sender, log, NFCT_TCP_IGNORE, + NF_TCP_LOG_SEQ_UNDER, + sender->td_end - receiver->td_maxwin - 1); if (!after(sack, receiver->td_end - MAXACKWINDOW(sender) - 1)) - return nf_tcp_log_invalid(skb, ct, hook_state, sender, NFCT_TCP_IGNORE, - "ignored ACK under lower bound %u (possible overly delayed)", - receiver->td_end - MAXACKWINDOW(sender) - 1); + return nf_tcp_store_invalid(ct, sender, log, NFCT_TCP_IGNORE, + NF_TCP_LOG_ACK_UNDER, + receiver->td_end - MAXACKWINDOW(sender) - 1); /* Take into account window scaling (RFC 1323). */ if (!tcph->syn) @@ -719,11 +761,8 @@ tcp_in_window(struct nf_conn *ct, enum i return NFCT_TCP_ACCEPT; } -static void __cold nf_tcp_handle_invalid(struct nf_conn *ct, - enum ip_conntrack_dir dir, - int index, - const struct sk_buff *skb, - const struct nf_hook_state *hook_state) +static bool __cold +nf_tcp_handle_invalid(struct nf_conn *ct, enum ip_conntrack_dir dir, int index) { const unsigned int *timeouts; const struct nf_tcp_net *tn; @@ -732,7 +771,7 @@ static void __cold nf_tcp_handle_invalid if (!test_bit(IPS_ASSURED_BIT, &ct->status) || test_bit(IPS_FIXED_TIMEOUT_BIT, &ct->status)) - return; + return false; /* We don't want to have connections hanging around in ESTABLISHED * state for long time 'just because' conntrack deemed a FIN/RST @@ -747,7 +786,7 @@ static void __cold nf_tcp_handle_invalid case TCP_FIN_SET: break; default: - return; + return false; } if (ct->proto.tcp.last_dir != dir && @@ -755,7 +794,7 @@ static void __cold nf_tcp_handle_invalid ct->proto.tcp.last_index == TCP_RST_SET)) { expires = nf_ct_expires(ct); if (expires < 120 * HZ) - return; + return false; tn = nf_tcp_pernet(nf_ct_net(ct)); timeouts = nf_ct_timeout_lookup(ct); @@ -764,16 +803,15 @@ static void __cold nf_tcp_handle_invalid timeout = READ_ONCE(timeouts[TCP_CONNTRACK_UNACK]); if (expires > timeout) { - nf_ct_l4proto_log_invalid(skb, ct, hook_state, - "packet (index %d, dir %d) response for index %d lower timeout to %u", - index, dir, ct->proto.tcp.last_index, timeout); - WRITE_ONCE(ct->timeout, timeout + nfct_time_stamp); + return true; } } else { ct->proto.tcp.last_index = index; ct->proto.tcp.last_dir = dir; } + + return false; } /* table of valid flag combinations - PUSH, ECE and CWR are always valid */ @@ -969,7 +1007,9 @@ int nf_conntrack_tcp_packet(struct nf_co struct nf_tcp_net *tn = nf_tcp_pernet(net); struct nf_conntrack_tuple *tuple; enum tcp_conntrack new_state, old_state; + struct nf_tcp_invalid_log log = {}; unsigned int index, *timeouts; + bool lowered_timeout = false; enum nf_ct_tcp_action res; enum ip_conntrack_dir dir; const struct tcphdr *th; @@ -1253,14 +1293,18 @@ int nf_conntrack_tcp_packet(struct nf_co } res = tcp_in_window(ct, dir, index, - skb, dataoff, th, state); + skb, dataoff, th, &log); switch (res) { case NFCT_TCP_IGNORE: spin_unlock_bh(&ct->lock); + nf_tcp_log_invalid(skb, ct, state, &log); return NF_ACCEPT; case NFCT_TCP_INVALID: - nf_tcp_handle_invalid(ct, dir, index, skb, state); + lowered_timeout = nf_tcp_handle_invalid(ct, dir, index); spin_unlock_bh(&ct->lock); + nf_tcp_log_invalid(skb, ct, state, &log); + if (lowered_timeout) + nf_ct_l4proto_log_invalid(skb, ct, state, "lowered timeout to UNACK"); return -NF_ACCEPT; case NFCT_TCP_ACCEPT: break;