From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793210888; b=ACAO96+J/kWBUFW3/iP5vPew7u6iQ3dxZR50bf97xbK/UBdZDcw9mgdIOZLANLc0pqiv iiYhpQ+c1b+BBLA8fODTq/Ry5ug/YU/er+ZbpH5MXd/+IJwfLv9JjoIcC3hcPI5iT8ZIF Nb7T+k5vQcGWIo4L0bzYbd3OjvdTivvqQe/KJCzbp06Uj/y8EKTkuVqgwzultuWV/zgGF XvmJ+YnsV5nJ/MD2cZ2wajpSRJddj84WuWwKxaFu1eQe99yb2ysUVkD6Iy4M4QkDkTAr3 RZkUnqOyFZbrJ2AsTBxw+zYu7zEj2Q3jsdeJWf5NK62x7vpNLoWWfAv6UgEcCfKw31w== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793210888; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:User-Agent:X-stable:X-Patchwork-Hint: MIME-Version:Content-Transfer-Encoding; bh=POh4Ai9CCnh9IM8RDjz8MRUROdF1JxhgrQcd47I7HBM=; b=k2T4WvM89VsQLfdhEodKvSDdayyeCRwVUhT9dWnDuDGWRV/JUDTsBeLFV48p9/Szxx8a paG/lnP0kUz+l9v3ibin/Od7a7vq/vkXUWL26/koNfg5zYcIAmLY3OUWy8DLO5Y4Rrtj3 2VPg6miiVnaKIJMRMUIYhaRCPHSrhLf69ENeLi37RMDYWznpj2COpmRfhQ63ns0FU6BCO HYkqjgFDsr6p4OvnyarZ3gnnwRwSVIVM7ysdSu/pygnCEEAdN78QKrMjByJT1eaKbYXb5 sexc30t9zIzB6Rq0VW0QCwFJG9OslCep2LH14xeUeigR5emouBCl/EZGyy9wub9T4og== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b="CuxE/evE"; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 29393606A31C; Wed, 28 Oct 2026 18:08:08 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=CuxE/evE Received: by smtp.kernel.org (Postfix) with ESMTPSA id 78F091F01825; Wed, 28 Oct 2026 18:08:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793210888; bh=POh4Ai9CCnh9IM8RDjz8MRUROdF1JxhgrQcd47I7HBM=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=CuxE/evEyavGpbNj0w61lFhDzVlmU1p47h+iuhVXsSHUME6+WXipe+8E7dO0CM/zW RqIiXklSNJzH5tdibwaY1GLzv/sQsbcIT8ibHuRbmYjEJ75y51vlAKasGUsIXaJY9Z lUTKZHzgTwVwMcEJbnMYiaH0XK9gCAGnlcXTYzNM= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Pablo Neira Ayuso , Florian Westphal , Sasha Levin Subject: [PATCH 5.15 185/571] netfilter: nf_tables: avoid skb access on nf_stolen Date: Wed, 28 Oct 2026 17:55:32 +0100 Message-ID: <20261028170012.400673825@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261028170008.009143722@linuxfoundation.org> References: <20261028170008.009143722@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: patches@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Florian Westphal [ Upstream commit e34b9ed96ce3b06c79bf884009b16961ca478f87 ] When verdict is NF_STOLEN, the skb might have been freed. When tracing is enabled, this can result in a use-after-free: 1. access to skb->nf_trace 2. access to skb->mark 3. computation of trace id 4. dump of packet payload To avoid 1, keep a cached copy of skb->nf_trace in the trace state struct. Refresh this copy whenever verdict is != STOLEN. Avoid 2 by skipping skb->mark access if verdict is STOLEN. 3 is avoided by precomputing the trace id. Only dump the packet when verdict is not "STOLEN". Reported-by: Pablo Neira Ayuso Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso Stable-dep-of: 8ec454dcd00c ("ipv6: sr: use skb_get_hash_net() in seg6_make_flowlabel()") Signed-off-by: Sasha Levin --- include/net/netfilter/nf_tables.h | 16 ++++++----- net/netfilter/nf_tables_core.c | 24 ++++++++++++++--- net/netfilter/nf_tables_trace.c | 44 +++++++++++++++++-------------- 3 files changed, 55 insertions(+), 29 deletions(-) diff --git a/include/net/netfilter/nf_tables.h b/include/net/netfilter/nf_tables.h index be271c66329e8..e05e2d85f67b2 100644 --- a/include/net/netfilter/nf_tables.h +++ b/include/net/netfilter/nf_tables.h @@ -1373,24 +1373,28 @@ void nft_unregister_flowtable_type(struct nf_flowtable_type *type); /** * struct nft_traceinfo - nft tracing information and state * + * @trace: other struct members are initialised + * @nf_trace: copy of skb->nf_trace before rule evaluation + * @type: event type (enum nft_trace_types) + * @skbid: hash of skb to be used as trace id + * @packet_dumped: packet headers sent in a previous traceinfo message * @pkt: pktinfo currently processed * @basechain: base chain currently processed * @chain: chain currently processed * @rule: rule that was evaluated * @verdict: verdict given by rule - * @type: event type (enum nft_trace_types) - * @packet_dumped: packet headers sent in a previous traceinfo message - * @trace: other struct members are initialised */ struct nft_traceinfo { + bool trace; + bool nf_trace; + bool packet_dumped; + enum nft_trace_types type:8; + u32 skbid; const struct nft_pktinfo *pkt; const struct nft_base_chain *basechain; const struct nft_chain *chain; const struct nft_rule *rule; const struct nft_verdict *verdict; - enum nft_trace_types type; - bool packet_dumped; - bool trace; }; void nft_trace_init(struct nft_traceinfo *info, const struct nft_pktinfo *pkt, diff --git a/net/netfilter/nf_tables_core.c b/net/netfilter/nf_tables_core.c index 2ab4216d2a903..4ee62c0da1b31 100644 --- a/net/netfilter/nf_tables_core.c +++ b/net/netfilter/nf_tables_core.c @@ -25,9 +25,7 @@ static noinline void __nft_trace_packet(struct nft_traceinfo *info, const struct nft_chain *chain, enum nft_trace_types type) { - const struct nft_pktinfo *pkt = info->pkt; - - if (!info->trace || !pkt->skb->nf_trace) + if (!info->trace || !info->nf_trace) return; info->chain = chain; @@ -42,11 +40,24 @@ static inline void nft_trace_packet(struct nft_traceinfo *info, enum nft_trace_types type) { if (static_branch_unlikely(&nft_trace_enabled)) { + const struct nft_pktinfo *pkt = info->pkt; + + info->nf_trace = pkt->skb->nf_trace; info->rule = rule; __nft_trace_packet(info, chain, type); } } +static inline void nft_trace_copy_nftrace(struct nft_traceinfo *info) +{ + if (static_branch_unlikely(&nft_trace_enabled)) { + const struct nft_pktinfo *pkt = info->pkt; + + if (info->trace) + info->nf_trace = pkt->skb->nf_trace; + } +} + static void nft_bitwise_fast_eval(const struct nft_expr *expr, struct nft_regs *regs) { @@ -85,6 +96,7 @@ static noinline void __nft_trace_verdict(struct nft_traceinfo *info, const struct nft_chain *chain, const struct nft_regs *regs) { + const struct nft_pktinfo *pkt = info->pkt; enum nft_trace_types type; switch (regs->verdict.code) { @@ -92,8 +104,13 @@ static noinline void __nft_trace_verdict(struct nft_traceinfo *info, case NFT_RETURN: type = NFT_TRACETYPE_RETURN; break; + case NF_STOLEN: + type = NFT_TRACETYPE_RULE; + /* can't access skb->nf_trace; use copy */ + break; default: type = NFT_TRACETYPE_RULE; + info->nf_trace = pkt->skb->nf_trace; break; } @@ -244,6 +261,7 @@ nft_do_chain(struct nft_pktinfo *pkt, void *priv) switch (regs.verdict.code) { case NFT_BREAK: regs.verdict.code = NFT_CONTINUE; + nft_trace_copy_nftrace(&info); continue; case NFT_CONTINUE: nft_trace_packet(&info, chain, rule, diff --git a/net/netfilter/nf_tables_trace.c b/net/netfilter/nf_tables_trace.c index 84a7dea46efae..ed4b067bfb6af 100644 --- a/net/netfilter/nf_tables_trace.c +++ b/net/netfilter/nf_tables_trace.c @@ -7,7 +7,7 @@ #include #include #include -#include +#include #include #include #include @@ -25,22 +25,6 @@ DEFINE_STATIC_KEY_FALSE(nft_trace_enabled); EXPORT_SYMBOL_GPL(nft_trace_enabled); -static int trace_fill_id(struct sk_buff *nlskb, struct sk_buff *skb) -{ - __be32 id; - - /* using skb address as ID results in a limited number of - * values (and quick reuse). - * - * So we attempt to use as many skb members that will not - * change while skb is with netfilter. - */ - id = (__be32)jhash_2words(hash32_ptr(skb), skb_get_hash(skb), - skb->skb_iif); - - return nla_put_be32(nlskb, NFTA_TRACE_ID, id); -} - static int trace_fill_header(struct sk_buff *nlskb, u16 type, const struct sk_buff *skb, int off, unsigned int len) @@ -186,6 +170,7 @@ void nft_trace_notify(struct nft_traceinfo *info) struct nlmsghdr *nlh; struct sk_buff *skb; unsigned int size; + u32 mark = 0; u16 event; if (!nfnetlink_has_listeners(nft_net(pkt), NFNLGRP_NFTRACE)) @@ -229,7 +214,7 @@ void nft_trace_notify(struct nft_traceinfo *info) if (nla_put_be32(skb, NFTA_TRACE_TYPE, htonl(info->type))) goto nla_put_failure; - if (trace_fill_id(skb, pkt->skb)) + if (nla_put_u32(skb, NFTA_TRACE_ID, info->skbid)) goto nla_put_failure; if (nla_put_string(skb, NFTA_TRACE_CHAIN, info->chain->name)) @@ -249,16 +234,24 @@ void nft_trace_notify(struct nft_traceinfo *info) case NFT_TRACETYPE_RULE: if (nft_verdict_dump(skb, NFTA_TRACE_VERDICT, info->verdict)) goto nla_put_failure; + + /* pkt->skb undefined iff NF_STOLEN, disable dump */ + if (info->verdict->code == NF_STOLEN) + info->packet_dumped = true; + else + mark = pkt->skb->mark; + break; case NFT_TRACETYPE_POLICY: + mark = pkt->skb->mark; + if (nla_put_be32(skb, NFTA_TRACE_POLICY, htonl(info->basechain->policy))) goto nla_put_failure; break; } - if (pkt->skb->mark && - nla_put_be32(skb, NFTA_TRACE_MARK, htonl(pkt->skb->mark))) + if (mark && nla_put_be32(skb, NFTA_TRACE_MARK, htonl(mark))) goto nla_put_failure; if (!info->packet_dumped) { @@ -283,9 +276,20 @@ void nft_trace_init(struct nft_traceinfo *info, const struct nft_pktinfo *pkt, const struct nft_verdict *verdict, const struct nft_chain *chain) { + static siphash_key_t trace_key __read_mostly; + struct sk_buff *skb = pkt->skb; + info->basechain = nft_base_chain(chain); info->trace = true; + info->nf_trace = pkt->skb->nf_trace; info->packet_dumped = false; info->pkt = pkt; info->verdict = verdict; + + net_get_random_once(&trace_key, sizeof(trace_key)); + + info->skbid = (u32)siphash_3u32(hash32_ptr(skb), + skb_get_hash(skb), + skb->skb_iif, + &trace_key); } -- 2.53.0