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 D1945471421; Tue, 21 Jul 2026 18:48:42 +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=1784659723; cv=none; b=QajSg54cF2fstDbynrVpHO/Ab0FuCKisrVHMk/SEAb6Vn2CmLcAmDDArewPpd/Qw4TjTa0vlJoJP18wXahm75CBpWvDtSFSHBiSmqJfIO8JDh2YatXiBA8zu46FgEgV5O2bCXeOeMcQgm3qAD+hyZpPnDH5RHtQYatjDAm3/BrE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784659723; c=relaxed/simple; bh=/3VBVgob8KqZ/bQS3uawBinvqfZsqL1Lxyvc/u2MFME=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=TvnuOfYhm6uUgm188yUASDmp95y4lbMOy/bSxOrWhvmJqznCthJ0RG/gDXUQpSohrpHUbG0E0f7CoTbSb7+0/2WAtaxjjhAK6zTlvAKg5y1gx6WTRvvprcQpOzDcWvBN6pQZG29DA0xDzfjSd0a2+DF7uUFhpFOAf2BDcpo/c+o= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=H4UcqoI2; 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="H4UcqoI2" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3D1F11F00A3E; Tue, 21 Jul 2026 18:48:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784659722; bh=cjHOH6TuOHMhhWYSpg2FwqZHc46zktWcnJZChq/EAqo=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=H4UcqoI2eazrN6WOVTMDGSyPPFeXHYsGoLRBiGn51cLF/4MpD6OyqVXBkD8GvcvQK 10d5dyqcVlcs3+5McXGZGB466L2w7y+MuIeyOnH3Ll74f9heOpV5HZQiYX9+U2X6Wq 4XyJPGijxvbsK2QXKbIbP4joJruMjWhv2t56HGSA= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Kyle Zeng , Victor Nogueira , Jamal Hadi Salim , Eric Dumazet , Jakub Kicinski , Sasha Levin Subject: [PATCH 7.1 0709/2077] net/sched: cls_flow: Dont expose folded kernel pointers Date: Tue, 21 Jul 2026 17:06:22 +0200 Message-ID: <20260721152609.518923571@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260721152552.646164743@linuxfoundation.org> References: <20260721152552.646164743@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 7.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jamal Hadi Salim [ Upstream commit f294fc71c4a0fa4964f6428a1b4e7929c1d83125 ] The flow classifier falls back to addr_fold() for fields that are missing from packet headers. In map mode, userspace controls mask, xor, rshift, addend and divisor, and can observe the resulting classid through class statistics. This allows a tc classifier in a user/network namespace to recover the 32-bit folded value of skb->sk, skb_dst() or skb_nfct(). Align with standard kernel practices for pointer hashing and replace the XOR folding with a keyed siphash (which is cryptographically secure) Fixes: e5dfb815181f ("[NET_SCHED]: Add flow classifier") Reported-by: Kyle Zeng Tested-by: Kyle Zeng Tested-by: Victor Nogueira Signed-off-by: Jamal Hadi Salim Reviewed-by: Eric Dumazet Link: https://patch.msgid.link/20260610101839.14135-1-jhs@mojatatu.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/sched/cls_flow.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/net/sched/cls_flow.c b/net/sched/cls_flow.c index ab364e4e468624..356c68ebc3895a 100644 --- a/net/sched/cls_flow.c +++ b/net/sched/cls_flow.c @@ -21,6 +21,7 @@ #include #include +#include #include #include #include @@ -57,11 +58,15 @@ struct flow_filter { struct rcu_work rwork; }; +static siphash_aligned_key_t flow_keys_secret __read_mostly; + static inline u32 addr_fold(void *addr) { - unsigned long a = (unsigned long)addr; - - return (a & 0xFFFFFFFF) ^ (BITS_PER_LONG > 32 ? a >> 32 : 0); +#ifdef CONFIG_64BIT + return (u32)siphash_1u64((u64)addr, &flow_keys_secret); +#else + return (u32)siphash_1u32((u32)addr, &flow_keys_secret); +#endif } static u32 flow_get_src(const struct sk_buff *skb, const struct flow_keys *flow) @@ -596,6 +601,7 @@ static int flow_init(struct tcf_proto *tp) return -ENOBUFS; INIT_LIST_HEAD(&head->filters); rcu_assign_pointer(tp->root, head); + net_get_random_once(&flow_keys_secret, sizeof(flow_keys_secret)); return 0; } -- 2.53.0