/*
* Copyright (C) 2017 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef LOG_TAG
#define LOG_TAG "bpfloader"
#endif
#include <arpa/inet.h>
#include <dirent.h>
#include <elf.h>
#include <error.h>
#include <fcntl.h>
#include <inttypes.h>
#include <linux/bpf.h>
#include <linux/unistd.h>
#include <net/if.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/mman.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <android-base/logging.h>
#include <android-base/macros.h>
#include <android-base/properties.h>
#include <android-base/stringprintf.h>
#include <android-base/strings.h>
#include <android-base/unique_fd.h>
#include <libbpf_android.h>
#include <log/log.h>
#include <netdutils/Misc.h>
#include <netdutils/Slice.h>
#include "bpf/BpfUtils.h"
using android::base::EndsWith;
using android::bpf::domain;
using std::string;
constexpr unsigned long long kTetheringApexDomainBitmask =
domainToBitmask(domain::tethering) |
domainToBitmask(domain::net_private) |
domainToBitmask(domain::net_shared) |
domainToBitmask(domain::netd_readonly) |
domainToBitmask(domain::netd_shared);
// see b/162057235. For arbitrary program types, the concern is that due to the lack of
// SELinux access controls over BPF program attachpoints, we have no way to control the
// attachment of programs to shared resources (or to detect when a shared resource
// has one BPF program replace another that is attached there)
constexpr bpf_prog_type kVendorAllowedProgTypes[] = {
BPF_PROG_TYPE_SOCKET_FILTER,
};
struct Location {
const char* const dir;
const char* const prefix;
unsigned long long allowedDomainBitmask;
const bpf_prog_type* allowedProgTypes = nullptr;
size_t allowedProgTypesLength = 0;
};
const Location locations[] = {
// S+ Tethering mainline module (network_stack): tether offload
{
.dir = "/apex/com.android.tethering/etc/bpf/",
.prefix = "tethering/",
.allowedDomainBitmask = kTetheringApexDomainBitmask,
},
// T+ Tethering mainline module (shared with netd & system server)
// netutils_wrapper (for iptables xt_bpf) has access to programs
{
.dir = "/apex/com.android.tethering/etc/bpf/netd_shared/",
.prefix = "netd_shared/",
.allowedDomainBitmask = kTetheringApexDomainBitmask,
},
// T+ Tethering mainline module (shared with netd & system server)
// netutils_wrapper has no access, netd has read only access
{
.dir = "/apex/com.android.tethering/etc/bpf/netd_readonly/",
.prefix = "netd_readonly/",
.allowedDomainBitmask = kTetheringApexDomainBitmask,
},
// T+ Tethering mainline module (shared with system server)
{
.dir = "/apex/com.android.tethering/etc/bpf/net_shared/",
.prefix = "net_shared/",
.allowedDomainBitmask = kTetheringApexDomainBitmask,
},
// T+ Tethering mainline module (not shared, just network_stack)
{
.dir = "/apex/com.android.tethering/etc/bpf/net_private/",
.prefix = "net_private/",
.allowedDomainBitmask = kTetheringApexDomainBitmask,
},
// Core operating system
{
.dir = "/system/etc/bpf/",
.prefix = "",
.allowedDomainBitmask = domainToBitmask(domain::platform),
},
// Vendor operating system
{
.dir = "/vendor/etc/bpf/",
.prefix = "vendor/",
.allowedDomainBitmask = domainToBitmask(domain::vendor),
.allowedProgTypes = kVendorAllowedProgTypes,
.allowedProgTypesLength = arraysize(kVendorAllowedProgTypes),
},
};
int loadAllElfObjects(const Location& location) {
int retVal = 0;
DIR* dir;
struct dirent* ent;
if ((dir = opendir(location.dir)) != NULL) {
while ((ent = readdir(dir)) != NULL) {
string s = ent->d_name;
if (!EndsWith(s, ".o")) continue;
string progPath(location.dir);
progPath += s;
bool critical;
int ret = android::bpf::loadProg(progPath.c_str(), &critical,
location.prefix,
location.allowedDomainBitmask,
location.allowedProgTypes,
location.allowedProgTypesLength);
if (ret) {
if (critical) retVal = ret;
ALOGE("Failed to load object: %s, ret: %s", progPath.c_str(), std::strerror(-ret));
} else {
ALOGI("Loaded object: %s", progPath.c_str());
}
}
closedir(dir);
}
return retVal;
}
void createSysFsBpfSubDir(const char* const prefix) {
if (*prefix) {
mode_t prevUmask = umask(0);
string s = "/sys/fs/bpf/";
s += prefix;
errno = 0;
int ret = mkdir(s.c_str(), S_ISVTX | S_IRWXU | S_IRWXG | S_IRWXO);
if (ret && errno != EEXIST) {
ALOGW("Failed to create directory: %s, ret: %s", s.c_str(), std::strerror(errno));
}
umask(prevUmask);
}
}
int main(int argc, char** argv) {
(void)argc;
android::base::InitLogging(argv, &android::base::KernelLogger);
// Create all the pin subdirectories
// (this must be done first to allow selinux_context and pin_subdir functionality,
// which could otherwise fail with ENOENT during object pinning or renaming,
// due to ordering issues)
for (const auto& location : locations) {
createSysFsBpfSubDir(location.prefix);
}
// Load all ELF objects, create programs and maps, and pin them
for (const auto& location : locations) {
if (loadAllElfObjects(location) != 0) {
ALOGE("=== CRITICAL FAILURE LOADING BPF PROGRAMS FROM %s ===", location.dir);
ALOGE("If this triggers reliably, you're probably missing kernel options or patches.");
ALOGE("If this triggers randomly, you might be hitting some memory allocation "
"problems or startup script race.");
ALOGE("--- DO NOT EXPECT SYSTEM TO BOOT SUCCESSFULLY ---");
sleep(20);
return 2;
}
}
int key = 1;
int value = 123;
android::base::unique_fd map(
android::bpf::createMap(BPF_MAP_TYPE_ARRAY, sizeof(key), sizeof(value), 2, 0));
if (android::bpf::writeToMapEntry(map, &key, &value, BPF_ANY)) {
ALOGE("Critical kernel bug - failure to write into index 1 of 2 element bpf map array.");
return 1;
}
if (android::base::SetProperty("bpf.progs_loaded", "1") == false) {
ALOGE("Failed to set bpf.progs_loaded property");
return 1;
}
return 0;
}