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 87BE452B1FE; Wed, 23 Sep 2026 14:36:28 +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=1790174189; cv=none; b=YuvPK2EqV26c+GUkL6BZv5PzDNTIgwAOzBO9Hnu7COY7tfcupX4FxOloswA6S0voz9DCvXFRRuFInFQIwIbvcqKyc8tSw+mLYrRZ+qhXiYoWjbOjMg8++TrosyjXV6NrtjFXPDUAJSuAUtPw1lr6ur7zow9fCC5wYEWuiKkUt+U= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790174189; c=relaxed/simple; bh=9CJpxKokBIuRTMqHgfP3Ec7jn7lWvX6v9iw+J8sAv8I=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Ed8LPkMtd21Q4fegPR3eNOzjmAalF6YIF0aCUOWUZohHazlcGYYy+eU2rA2AxOLfwA4qsJ81yDEEzLsT7rpVeQPVEs9gVGv2Z2ucgcNzTH4P67+WnuwThCdtzikaz6zzuBv17sxj80FmmlPtMlWOPyN9pgWdN38M99ga5RyoWUo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=ICZ6A1lG; 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="ICZ6A1lG" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 927BA1F00893; Wed, 23 Sep 2026 14:36:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1790174188; bh=LgpQsqe50jw50ndot/WUd275fB2z8yt3h3sQYfPTuJY=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=ICZ6A1lGSyu5B3LH33vewGlGUThaFSioNH03uznEEpRo8V9U51NqRPqpIiRxq2bRs ypcxu4IorGNvBsRW8+xWjvJ05xzcqoWAu4t8nDujv1wowz1zuXsucRX4OIcuD72bFK HQ1PQpST+hDK2BB4NjDJRMBI9xo/xzoX1FNt/0ts= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Sabrina Dubroca , Simon Horman , Steffen Klassert , Sasha Levin Subject: [PATCH 6.18 019/398] xfrm: avoid RCU warnings around the per-netns netlink socket Date: Wed, 23 Sep 2026 16:01:33 +0200 Message-ID: <20260923140643.933337229@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260923140643.441954610@linuxfoundation.org> References: <20260923140643.441954610@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 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Sabrina Dubroca [ Upstream commit d87f8bc47fbf012a7f115e311d0603d97e47c34c ] net->xfrm.nlsk is used in 2 types of contexts: - fully under RCU, with rcu_read_lock + rcu_dereference and a NULL check - in the netlink handlers, with requests coming from a userspace socket In the 2nd case, net->xfrm.nlsk is guaranteed to stay non-NULL and the object is alive, since we can't enter the netns destruction path while the user socket holds a reference on the netns. After adding the __rcu annotation to netns_xfrm.nlsk (which silences sparse warnings in the RCU users and __net_init code), we need to tell sparse that the 2nd case is safe. Add a helper for that. Signed-off-by: Sabrina Dubroca Reviewed-by: Simon Horman Signed-off-by: Steffen Klassert Stable-dep-of: d1ebd9081879 ("xfrm: fix compat ALLOCSPI request use-after-free") Signed-off-by: Sasha Levin --- include/net/netns/xfrm.h | 2 +- net/xfrm/xfrm_user.c | 25 +++++++++++++++++-------- 2 files changed, 18 insertions(+), 9 deletions(-) diff --git a/include/net/netns/xfrm.h b/include/net/netns/xfrm.h index 23dd647fe0248..b73983a17e088 100644 --- a/include/net/netns/xfrm.h +++ b/include/net/netns/xfrm.h @@ -59,7 +59,7 @@ struct netns_xfrm { struct list_head inexact_bins; - struct sock *nlsk; + struct sock __rcu *nlsk; struct sock *nlsk_stash; u32 sysctl_aevent_etime; diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c index 0f0384b6a11d0..4e80e1b5ef4b4 100644 --- a/net/xfrm/xfrm_user.c +++ b/net/xfrm/xfrm_user.c @@ -35,6 +35,15 @@ #endif #include +static struct sock *xfrm_net_nlsk(const struct net *net, const struct sk_buff *skb) +{ + /* get the source of this request, see netlink_unicast_kernel */ + const struct sock *sk = NETLINK_CB(skb).sk; + + /* sk is refcounted, the netns stays alive and nlsk with it */ + return rcu_dereference_protected(net->xfrm.nlsk, sk->sk_net_refcnt); +} + static int verify_one_alg(struct nlattr **attrs, enum xfrm_attr_type_t type, struct netlink_ext_ack *extack) { @@ -1727,7 +1736,7 @@ static int xfrm_get_spdinfo(struct sk_buff *skb, struct nlmsghdr *nlh, err = build_spdinfo(r_skb, net, sportid, seq, *flags); BUG_ON(err < 0); - return nlmsg_unicast(net->xfrm.nlsk, r_skb, sportid); + return nlmsg_unicast(xfrm_net_nlsk(net, skb), r_skb, sportid); } static inline unsigned int xfrm_sadinfo_msgsize(void) @@ -1787,7 +1796,7 @@ static int xfrm_get_sadinfo(struct sk_buff *skb, struct nlmsghdr *nlh, err = build_sadinfo(r_skb, net, sportid, seq, *flags); BUG_ON(err < 0); - return nlmsg_unicast(net->xfrm.nlsk, r_skb, sportid); + return nlmsg_unicast(xfrm_net_nlsk(net, skb), r_skb, sportid); } static int xfrm_get_sa(struct sk_buff *skb, struct nlmsghdr *nlh, @@ -1807,7 +1816,7 @@ static int xfrm_get_sa(struct sk_buff *skb, struct nlmsghdr *nlh, if (IS_ERR(resp_skb)) { err = PTR_ERR(resp_skb); } else { - err = nlmsg_unicast(net->xfrm.nlsk, resp_skb, NETLINK_CB(skb).portid); + err = nlmsg_unicast(xfrm_net_nlsk(net, skb), resp_skb, NETLINK_CB(skb).portid); } xfrm_state_put(x); out_noput: @@ -1898,7 +1907,7 @@ static int xfrm_alloc_userspi(struct sk_buff *skb, struct nlmsghdr *nlh, } } - err = nlmsg_unicast(net->xfrm.nlsk, resp_skb, NETLINK_CB(skb).portid); + err = nlmsg_unicast(xfrm_net_nlsk(net, skb), resp_skb, NETLINK_CB(skb).portid); out: xfrm_state_put(x); @@ -2542,7 +2551,7 @@ static int xfrm_get_default(struct sk_buff *skb, struct nlmsghdr *nlh, r_up->out = READ_ONCE(net->xfrm.policy_default[XFRM_POLICY_OUT]); nlmsg_end(r_skb, r_nlh); - return nlmsg_unicast(net->xfrm.nlsk, r_skb, portid); + return nlmsg_unicast(xfrm_net_nlsk(net, skb), r_skb, portid); } static int xfrm_get_policy(struct sk_buff *skb, struct nlmsghdr *nlh, @@ -2608,7 +2617,7 @@ static int xfrm_get_policy(struct sk_buff *skb, struct nlmsghdr *nlh, if (IS_ERR(resp_skb)) { err = PTR_ERR(resp_skb); } else { - err = nlmsg_unicast(net->xfrm.nlsk, resp_skb, + err = nlmsg_unicast(xfrm_net_nlsk(net, skb), resp_skb, NETLINK_CB(skb).portid); } } else { @@ -2787,7 +2796,7 @@ static int xfrm_get_ae(struct sk_buff *skb, struct nlmsghdr *nlh, return err; } - err = nlmsg_unicast(net->xfrm.nlsk, r_skb, NETLINK_CB(skb).portid); + err = nlmsg_unicast(xfrm_net_nlsk(net, skb), r_skb, NETLINK_CB(skb).portid); spin_unlock_bh(&x->lock); xfrm_state_put(x); return err; @@ -3491,7 +3500,7 @@ static int xfrm_user_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh, goto err; } - err = netlink_dump_start(net->xfrm.nlsk, skb, nlh, &c); + err = netlink_dump_start(xfrm_net_nlsk(net, skb), skb, nlh, &c); goto err; } -- 2.53.0