From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from Chamillionaire.breakpoint.cc (Chamillionaire.breakpoint.cc [91.216.245.30]) (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 C75F515CD64 for ; Sat, 7 Sep 2024 14:53:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.216.245.30 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725720815; cv=none; b=uy6RGgGDlXXpTvBKbQb2d4YCy0UplAmYWXWhr2j84swSYgDhGotG0e74AvHy0vX+EBAXx90tOVlpU3K7fiyKqbCS/DXASRT2Q9mid+nazUk2ZqsDi9SdmzHb6Z2a/FOMgRidINYhYSvAEgIajB2WYkEKkkectIY5M0d+RGLhiRY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725720815; c=relaxed/simple; bh=AM7lrTKklEpWNKJ8ObehswacxRHfagf8RG6MUx5gBRs=; h=From:To:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=kFpSv019W9DkNHuhxBs3XhH14eNFl2LgZ3Ceo/LtkXd0eXo3eccSY2g4ftABI2yyBcLSglKriX05KmcaqeJTXnJDvP4uujihYiNlHdxoJURepD8DRBUBocw1J6/wdJy91WiXQAwdSOauPkkV3Aj89J1j/FofBZkR1iEkdlPO9CE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=strlen.de; spf=pass smtp.mailfrom=breakpoint.cc; arc=none smtp.client-ip=91.216.245.30 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=strlen.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=breakpoint.cc Received: from fw by Chamillionaire.breakpoint.cc with local (Exim 4.92) (envelope-from ) id 1smw71-0006SP-3x; Sat, 07 Sep 2024 16:08:27 +0200 From: Florian Westphal To: netfilter-devel Subject: [PATCH nf v2 2/2] netfilter: nft_socket: make cgroupsv2 matching work with namespaces Date: Sat, 7 Sep 2024 16:07:49 +0200 Message-ID: <20240907140824.39841-1-fw@strlen.de> X-Mailer: git-send-email 2.46.0 In-Reply-To: <202409070305.pBDk8EVS-lkp@intel.com> References: <202409070305.pBDk8EVS-lkp@intel.com> Precedence: bulk X-Mailing-List: netfilter-devel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit When running in container environmment, /sys/fs/cgroup/ might not be the real root node of the sk-attached cgroup. Example: In container: % stat /sys//fs/cgroup/ Device: 0,21 Inode: 2214 .. % stat /sys/fs/cgroup/foo Device: 0,21 Inode: 2264 .. The expectation would be for: nft add rule .. socket cgroupv2 level 1 "foo" counter to match traffic from a process that got added to "foo" via "echo $pid > /sys/fs/cgroup/foo/cgroup.procs". However, 'level 3' is needed to make this work. Seen from initial namespace, the complete hierarchy is: % stat /sys/fs/cgroup/system.slice/docker-.../foo Device: 0,21 Inode: 2264 .. i.e. hierarchy is 0 1 2 3 / -> system.slice -> docker-1... -> foo ... but the container doesn't know that its "/" is the "docker-1.." cgroup. Current code will retrieve the 'system.slice' cgroup node and store its kn->id in the destination register, so compare with 2264 ("foo" cgroup id) will not match. Fetch "/" cgroup from ->init() and add its level to the level we try to extract. cgroup root-level is 0 for the init-namespace or the level of the ancestor that is exposed as the cgroup root inside the container. In the above case, cgrp->level of "/" resolved in the container is 2 (docker-1...scope/) and request for 'level 1' will get adjusted to fetch the actual level (3). v2: use CONFIG_SOCK_CGROUP_DATA, eval function depends on it. (kernel test robot) Cc: cgroups@vger.kernel.org Fixes: e0bb96db96f8 ("netfilter: nft_socket: add support for cgroupsv2") Reported-by: Nadia Pinaeva Signed-off-by: Florian Westphal --- net/netfilter/nft_socket.c | 41 +++++++++++++++++++++++++++++++++++--- 1 file changed, 38 insertions(+), 3 deletions(-) diff --git a/net/netfilter/nft_socket.c b/net/netfilter/nft_socket.c index 765ffd6e06bc..12cdff640492 100644 --- a/net/netfilter/nft_socket.c +++ b/net/netfilter/nft_socket.c @@ -9,7 +9,8 @@ struct nft_socket { enum nft_socket_keys key:8; - u8 level; + u8 level; /* cgroupv2 level to extract */ + u8 level_user; /* cgroupv2 level provided by userspace */ u8 len; union { u8 dreg; @@ -53,6 +54,28 @@ nft_sock_get_eval_cgroupv2(u32 *dest, struct sock *sk, const struct nft_pktinfo memcpy(dest, &cgid, sizeof(u64)); return true; } + +/* process context only, uses current->nsproxy. */ +static noinline int nft_socket_cgroup_subtree_level(void) +{ + struct cgroup *cgrp = cgroup_get_from_path("/"); + int level; + + if (!cgrp) + return -ENOENT; + + level = cgrp->level; + + cgroup_put(cgrp); + + if (WARN_ON_ONCE(level > 255)) + return -ERANGE; + + if (WARN_ON_ONCE(level < 0)) + return -EINVAL; + + return level; +} #endif static struct sock *nft_socket_do_lookup(const struct nft_pktinfo *pkt) @@ -174,9 +197,10 @@ static int nft_socket_init(const struct nft_ctx *ctx, case NFT_SOCKET_MARK: len = sizeof(u32); break; -#ifdef CONFIG_CGROUPS +#ifdef CONFIG_SOCK_CGROUP_DATA case NFT_SOCKET_CGROUPV2: { unsigned int level; + int err; if (!tb[NFTA_SOCKET_LEVEL]) return -EINVAL; @@ -185,6 +209,17 @@ static int nft_socket_init(const struct nft_ctx *ctx, if (level > 255) return -EOPNOTSUPP; + err = nft_socket_cgroup_subtree_level(); + if (err < 0) + return err; + + priv->level_user = level; + + level += err; + /* Implies a giant cgroup tree */ + if (WARN_ON_ONCE(level > 255)) + return -EOPNOTSUPP; + priv->level = level; len = sizeof(u64); break; @@ -209,7 +244,7 @@ static int nft_socket_dump(struct sk_buff *skb, if (nft_dump_register(skb, NFTA_SOCKET_DREG, priv->dreg)) return -1; if (priv->key == NFT_SOCKET_CGROUPV2 && - nla_put_be32(skb, NFTA_SOCKET_LEVEL, htonl(priv->level))) + nla_put_be32(skb, NFTA_SOCKET_LEVEL, htonl(priv->level_user))) return -1; return 0; } -- 2.46.0