From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 D351B222587; Mon, 13 Oct 2025 15:28:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760369327; cv=none; b=sScXnoIrNTpWytqyufsQm2ou97kM9ABC0JU2KTiI1G9Zu8UFIwMIjrfGKLqhBxVozM3ZsvC5cAsxGwFAHPkSo40PoCL/c4s8TH46Fo9CFw9u+uRK3Tx1Ri4fhFLUemxmwjfmpGpalFHOeGtMqcCEKP5rVRngXW1WbinnWiXSCN8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760369327; c=relaxed/simple; bh=4SFj6E+CUYiuLIVHpjG/2/WLKKcLL4eSwDwvhGIYByY=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Dd07ySVOixLEjsBlCc5eqTDkcNjd1b7HIc+OkeRbbLJg8PkpOh2LBjGWwFn5tngOxaLm65Dyqhge5eMmXsOMpWpjToyAMdvZPT6NAsrcMLrSeq85B5Fn4y+zffO/0OX+EdD1eMbGW2CHVeORFbZjN08J2HV8OQbRcoIoDhi1fco= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=wN87pZL+; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="wN87pZL+" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 19CD7C4CEFE; Mon, 13 Oct 2025 15:28:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1760369327; bh=4SFj6E+CUYiuLIVHpjG/2/WLKKcLL4eSwDwvhGIYByY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=wN87pZL+EjubMwnytQCj4EsXsHdDDdy5UUOx6ICHlZaoQ/zGGvxdb/oG+7Q3TV6id qfcs+A6a9pdPSPoJAebVG6e1Nbu27SwWqHmd9RcxCoUjEe1AlgIrB9jjZ7QEOt1acB bhzEFBN813ZeTs8dkea4ceColWoVNRxdc2Kx0gXI= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Yinhao Hu , Kaiyan Mei , Dongliang Mu , Daniel Borkmann , Alexei Starovoitov , Sasha Levin Subject: [PATCH 6.17 208/563] bpf: Enforce expected_attach_type for tailcall compatibility Date: Mon, 13 Oct 2025 16:41:09 +0200 Message-ID: <20251013144418.821103745@linuxfoundation.org> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20251013144411.274874080@linuxfoundation.org> References: <20251013144411.274874080@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 6.17-stable review patch. If anyone has any objections, please let me know. ------------------ From: Daniel Borkmann [ Upstream commit 4540aed51b12bc13364149bf95f6ecef013197c0 ] Yinhao et al. recently reported: Our fuzzer tool discovered an uninitialized pointer issue in the bpf_prog_test_run_xdp() function within the Linux kernel's BPF subsystem. This leads to a NULL pointer dereference when a BPF program attempts to deference the txq member of struct xdp_buff object. The test initializes two programs of BPF_PROG_TYPE_XDP: progA acts as the entry point for bpf_prog_test_run_xdp() and its expected_attach_type can neither be of be BPF_XDP_DEVMAP nor BPF_XDP_CPUMAP. progA calls into a slot of a tailcall map it owns. progB's expected_attach_type must be BPF_XDP_DEVMAP to pass xdp_is_valid_access() validation. The program returns struct xdp_md's egress_ifindex, and the latter is only allowed to be accessed under mentioned expected_attach_type. progB is then inserted into the tailcall which progA calls. The underlying issue goes beyond XDP though. Another example are programs of type BPF_PROG_TYPE_CGROUP_SOCK_ADDR. sock_addr_is_valid_access() as well as sock_addr_func_proto() have different logic depending on the programs' expected_attach_type. Similarly, a program attached to BPF_CGROUP_INET4_GETPEERNAME should not be allowed doing a tailcall into a program which calls bpf_bind() out of BPF which is only enabled for BPF_CGROUP_INET4_CONNECT. In short, specifying expected_attach_type allows to open up additional functionality or restrictions beyond what the basic bpf_prog_type enables. The use of tailcalls must not violate these constraints. Fix it by enforcing expected_attach_type in __bpf_prog_map_compatible(). Note that we only enforce this for tailcall maps, but not for BPF devmaps or cpumaps: There, the programs are invoked through dev_map_bpf_prog_run*() and cpu_map_bpf_prog_run*() which set up a new environment / context and therefore these situations are not prone to this issue. Fixes: 5e43f899b03a ("bpf: Check attach type at prog load time") Reported-by: Yinhao Hu Reported-by: Kaiyan Mei Reviewed-by: Dongliang Mu Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/r/20250926171201.188490-1-daniel@iogearbox.net Signed-off-by: Alexei Starovoitov Signed-off-by: Sasha Levin --- include/linux/bpf.h | 1 + kernel/bpf/core.c | 5 +++++ 2 files changed, 6 insertions(+) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index cc700925b802f..84826dc0a3268 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -285,6 +285,7 @@ struct bpf_map_owner { bool xdp_has_frags; u64 storage_cookie[MAX_BPF_CGROUP_STORAGE_TYPE]; const struct btf_type *attach_func_proto; + enum bpf_attach_type expected_attach_type; }; struct bpf_map { diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index e4568d44e8279..f6dd071f5e38c 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -2393,6 +2393,7 @@ static bool __bpf_prog_map_compatible(struct bpf_map *map, map->owner->type = prog_type; map->owner->jited = fp->jited; map->owner->xdp_has_frags = aux->xdp_has_frags; + map->owner->expected_attach_type = fp->expected_attach_type; map->owner->attach_func_proto = aux->attach_func_proto; for_each_cgroup_storage_type(i) { map->owner->storage_cookie[i] = @@ -2404,6 +2405,10 @@ static bool __bpf_prog_map_compatible(struct bpf_map *map, ret = map->owner->type == prog_type && map->owner->jited == fp->jited && map->owner->xdp_has_frags == aux->xdp_has_frags; + if (ret && + map->map_type == BPF_MAP_TYPE_PROG_ARRAY && + map->owner->expected_attach_type != fp->expected_attach_type) + ret = false; for_each_cgroup_storage_type(i) { if (!ret) break; -- 2.51.0