ae58e7e4a7
This is to prevent platform and tethering mainline module updatable code from being to step on each other. Bug: 218408035 Test: TreeHugger Signed-off-by: Maciej Żenczykowski <maze@google.com> Change-Id: I8f4ffafb72efb17d07aaf993892c5d395bd6876d
244 lines
9 KiB
C++
244 lines
9 KiB
C++
/*
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* Copyright (C) 2017 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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#ifndef LOG_TAG
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#define LOG_TAG "bpfloader"
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#endif
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#include <arpa/inet.h>
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#include <dirent.h>
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#include <elf.h>
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#include <error.h>
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#include <fcntl.h>
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#include <inttypes.h>
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#include <linux/bpf.h>
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#include <linux/unistd.h>
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#include <net/if.h>
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#include <stdint.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <sys/mman.h>
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#include <sys/socket.h>
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#include <sys/stat.h>
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#include <sys/types.h>
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#include <android-base/logging.h>
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#include <android-base/macros.h>
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#include <android-base/properties.h>
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#include <android-base/stringprintf.h>
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#include <android-base/strings.h>
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#include <android-base/unique_fd.h>
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#include <libbpf_android.h>
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#include <log/log.h>
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#include <netdutils/Misc.h>
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#include <netdutils/Slice.h>
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#include "bpf/BpfUtils.h"
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using android::base::EndsWith;
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using android::bpf::domain;
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using std::string;
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constexpr unsigned long long kTetheringApexDomainBitmask =
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domainToBitmask(domain::tethering) |
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domainToBitmask(domain::net_private) |
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domainToBitmask(domain::net_shared) |
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domainToBitmask(domain::netd_readonly) |
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domainToBitmask(domain::netd_shared);
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// Programs shipped inside the tethering apex should be limited to networking stuff,
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// as KPROBE, PERF_EVENT, TRACEPOINT are dangerous to use from mainline updatable code,
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// since they are less stable abi/api and may conflict with platform uses of bpf.
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constexpr bpf_prog_type kTetheringApexAllowedProgTypes[] = {
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BPF_PROG_TYPE_CGROUP_SOCK_ADDR,
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BPF_PROG_TYPE_CGROUP_SKB,
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BPF_PROG_TYPE_CGROUP_SOCK,
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BPF_PROG_TYPE_SCHED_ACT,
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BPF_PROG_TYPE_SCHED_CLS,
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BPF_PROG_TYPE_SOCKET_FILTER,
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BPF_PROG_TYPE_XDP,
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};
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// Networking-related program types are limited to the Tethering Apex
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// to prevent things from breaking due to conflicts on mainline updates
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// (exception made for socket filters, ie. xt_bpf for potential use in iptables,
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// or for attaching to sockets directly)
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constexpr bpf_prog_type kPlatformAllowedProgTypes[] = {
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BPF_PROG_TYPE_KPROBE,
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BPF_PROG_TYPE_PERF_EVENT,
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BPF_PROG_TYPE_SOCKET_FILTER,
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BPF_PROG_TYPE_TRACEPOINT,
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};
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// see b/162057235. For arbitrary program types, the concern is that due to the lack of
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// SELinux access controls over BPF program attachpoints, we have no way to control the
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// attachment of programs to shared resources (or to detect when a shared resource
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// has one BPF program replace another that is attached there)
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constexpr bpf_prog_type kVendorAllowedProgTypes[] = {
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BPF_PROG_TYPE_SOCKET_FILTER,
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};
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struct Location {
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const char* const dir;
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const char* const prefix;
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unsigned long long allowedDomainBitmask;
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const bpf_prog_type* allowedProgTypes = nullptr;
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size_t allowedProgTypesLength = 0;
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};
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const Location locations[] = {
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// S+ Tethering mainline module (network_stack): tether offload
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{
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.dir = "/apex/com.android.tethering/etc/bpf/",
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.prefix = "tethering/",
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.allowedDomainBitmask = kTetheringApexDomainBitmask,
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.allowedProgTypes = kTetheringApexAllowedProgTypes,
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.allowedProgTypesLength = arraysize(kTetheringApexAllowedProgTypes),
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},
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// T+ Tethering mainline module (shared with netd & system server)
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// netutils_wrapper (for iptables xt_bpf) has access to programs
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{
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.dir = "/apex/com.android.tethering/etc/bpf/netd_shared/",
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.prefix = "netd_shared/",
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.allowedDomainBitmask = kTetheringApexDomainBitmask,
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.allowedProgTypes = kTetheringApexAllowedProgTypes,
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.allowedProgTypesLength = arraysize(kTetheringApexAllowedProgTypes),
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},
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// T+ Tethering mainline module (shared with netd & system server)
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// netutils_wrapper has no access, netd has read only access
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{
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.dir = "/apex/com.android.tethering/etc/bpf/netd_readonly/",
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.prefix = "netd_readonly/",
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.allowedDomainBitmask = kTetheringApexDomainBitmask,
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.allowedProgTypes = kTetheringApexAllowedProgTypes,
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.allowedProgTypesLength = arraysize(kTetheringApexAllowedProgTypes),
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},
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// T+ Tethering mainline module (shared with system server)
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{
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.dir = "/apex/com.android.tethering/etc/bpf/net_shared/",
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.prefix = "net_shared/",
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.allowedDomainBitmask = kTetheringApexDomainBitmask,
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.allowedProgTypes = kTetheringApexAllowedProgTypes,
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.allowedProgTypesLength = arraysize(kTetheringApexAllowedProgTypes),
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},
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// T+ Tethering mainline module (not shared, just network_stack)
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{
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.dir = "/apex/com.android.tethering/etc/bpf/net_private/",
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.prefix = "net_private/",
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.allowedDomainBitmask = kTetheringApexDomainBitmask,
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.allowedProgTypes = kTetheringApexAllowedProgTypes,
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.allowedProgTypesLength = arraysize(kTetheringApexAllowedProgTypes),
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},
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// Core operating system
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{
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.dir = "/system/etc/bpf/",
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.prefix = "",
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.allowedDomainBitmask = domainToBitmask(domain::platform),
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.allowedProgTypes = kPlatformAllowedProgTypes,
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.allowedProgTypesLength = arraysize(kPlatformAllowedProgTypes),
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},
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// Vendor operating system
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{
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.dir = "/vendor/etc/bpf/",
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.prefix = "vendor/",
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.allowedDomainBitmask = domainToBitmask(domain::vendor),
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.allowedProgTypes = kVendorAllowedProgTypes,
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.allowedProgTypesLength = arraysize(kVendorAllowedProgTypes),
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},
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};
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int loadAllElfObjects(const Location& location) {
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int retVal = 0;
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DIR* dir;
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struct dirent* ent;
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if ((dir = opendir(location.dir)) != NULL) {
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while ((ent = readdir(dir)) != NULL) {
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string s = ent->d_name;
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if (!EndsWith(s, ".o")) continue;
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string progPath(location.dir);
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progPath += s;
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bool critical;
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int ret = android::bpf::loadProg(progPath.c_str(), &critical,
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location.prefix,
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location.allowedDomainBitmask,
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location.allowedProgTypes,
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location.allowedProgTypesLength);
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if (ret) {
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if (critical) retVal = ret;
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ALOGE("Failed to load object: %s, ret: %s", progPath.c_str(), std::strerror(-ret));
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} else {
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ALOGI("Loaded object: %s", progPath.c_str());
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}
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}
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closedir(dir);
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}
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return retVal;
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}
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void createSysFsBpfSubDir(const char* const prefix) {
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if (*prefix) {
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mode_t prevUmask = umask(0);
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string s = "/sys/fs/bpf/";
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s += prefix;
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errno = 0;
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int ret = mkdir(s.c_str(), S_ISVTX | S_IRWXU | S_IRWXG | S_IRWXO);
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if (ret && errno != EEXIST) {
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ALOGW("Failed to create directory: %s, ret: %s", s.c_str(), std::strerror(errno));
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}
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umask(prevUmask);
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}
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}
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int main(int argc, char** argv) {
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(void)argc;
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android::base::InitLogging(argv, &android::base::KernelLogger);
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// Create all the pin subdirectories
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// (this must be done first to allow selinux_context and pin_subdir functionality,
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// which could otherwise fail with ENOENT during object pinning or renaming,
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// due to ordering issues)
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for (const auto& location : locations) {
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createSysFsBpfSubDir(location.prefix);
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}
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// Load all ELF objects, create programs and maps, and pin them
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for (const auto& location : locations) {
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if (loadAllElfObjects(location) != 0) {
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ALOGE("=== CRITICAL FAILURE LOADING BPF PROGRAMS FROM %s ===", location.dir);
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ALOGE("If this triggers reliably, you're probably missing kernel options or patches.");
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ALOGE("If this triggers randomly, you might be hitting some memory allocation "
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"problems or startup script race.");
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ALOGE("--- DO NOT EXPECT SYSTEM TO BOOT SUCCESSFULLY ---");
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sleep(20);
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return 2;
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}
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}
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if (android::base::SetProperty("bpf.progs_loaded", "1") == false) {
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ALOGE("Failed to set bpf.progs_loaded property");
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return 1;
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}
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return 0;
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}
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