ccce4a3382
InProcessTethering runs as system_server (uid/gid AID_SYSTEM) instead of as the network_stack (uid/gid AID_NETWORK_STACK). Additionally only the network_stack has access to the default selinux context of /sys/fs/bpf/tethering, which is fs_bpf_tethering, so we need to use 'fs_bpf_net_shared' instead. Bug: 190523685 Bug: 236925089 Test: TreeHugger Signed-off-by: Maciej Żenczykowski <maze@google.com> Change-Id: Ibb6ae255dcd8a8e8049be112055f60c3b2cf7df0
72 lines
2.4 KiB
C
72 lines
2.4 KiB
C
/*
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* Copyright (C) 2021 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <linux/if_ether.h>
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#include <linux/in.h>
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#include <linux/ip.h>
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#ifdef BTF
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// BTF is incompatible with bpfloaders < v0.10, hence for S (v0.2) we must
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// ship a different file than for later versions, but we need bpfloader v0.25+
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// for obj@ver.o support
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#define BPFLOADER_MIN_VER BPFLOADER_OBJ_AT_VER_VERSION
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#else /* BTF */
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// The resulting .o needs to load on the Android S bpfloader
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#define BPFLOADER_MIN_VER BPFLOADER_S_VERSION
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#define BPFLOADER_MAX_VER BPFLOADER_OBJ_AT_VER_VERSION
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#endif /* BTF */
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// Warning: values other than AID_ROOT don't work for map uid on BpfLoader < v0.21
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#define TETHERING_UID AID_ROOT
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#ifdef INPROCESS
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#define DEFAULT_BPF_MAP_SELINUX_CONTEXT "fs_bpf_net_shared"
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#define DEFAULT_BPF_PROG_SELINUX_CONTEXT "fs_bpf_net_shared"
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#define TETHERING_GID AID_SYSTEM
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#else
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#define TETHERING_GID AID_NETWORK_STACK
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#endif
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#include "bpf_helpers.h"
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#include "bpf_net_helpers.h"
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#include "bpf_tethering.h"
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// Used only by TetheringPrivilegedTests, not by production code.
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DEFINE_BPF_MAP_GRW(tether_downstream6_map, HASH, TetherDownstream6Key, Tether6Value, 16,
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TETHERING_GID)
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// Used only by BpfBitmapTest, not by production code.
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DEFINE_BPF_MAP_GRW(bitmap, ARRAY, int, uint64_t, 2, TETHERING_GID)
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DEFINE_BPF_PROG_KVER("xdp/drop_ipv4_udp_ether", TETHERING_UID, TETHERING_GID,
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xdp_test, KVER(5, 9, 0))
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(struct xdp_md *ctx) {
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void *data = (void *)(long)ctx->data;
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void *data_end = (void *)(long)ctx->data_end;
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struct ethhdr *eth = data;
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int hsize = sizeof(*eth);
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struct iphdr *ip = data + hsize;
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hsize += sizeof(struct iphdr);
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if (data + hsize > data_end) return XDP_PASS;
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if (eth->h_proto != htons(ETH_P_IP)) return XDP_PASS;
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if (ip->protocol == IPPROTO_UDP) return XDP_DROP;
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return XDP_PASS;
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}
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LICENSE("Apache 2.0");
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