bpfloader/BpfLoader.cpp - LeafOS-Project/android_system_bpf - Gitiles

 /*
  * 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 "BpfSyscallWrappers.h"
 #include "bpf/BpfUtils.h"

 using android::base::EndsWith;
 using android::bpf::domain;
 using std::string;

 bool exists(const char* const path) {
     int v = access(path, F_OK);
     if (!v) {
         ALOGI("%s exists.", path);
         return true;
     }
     if (errno == ENOENT) return false;
     ALOGE("FATAL: access(%s, F_OK) -> %d [%d:%s]", path, v, errno, strerror(errno));
     abort();  // can only hit this if permissions (likely selinux) are screwed up
 }

 // Networking-related program types are limited to the Tethering Apex
 // to prevent things from breaking due to conflicts on mainline updates
 // (exception made for socket filters, ie. xt_bpf for potential use in iptables,
 // or for attaching to sockets directly)
 constexpr bpf_prog_type kPlatformAllowedProgTypes[] = {
         BPF_PROG_TYPE_KPROBE,
         BPF_PROG_TYPE_PERF_EVENT,
         BPF_PROG_TYPE_SOCKET_FILTER,
         BPF_PROG_TYPE_TRACEPOINT,
         BPF_PROG_TYPE_UNSPEC,  // Will be replaced with fuse bpf program type
 };

 // 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,
 };


 const android::bpf::Location locations[] = {
         // Core operating system
         {
                 .dir = "/system/etc/bpf/",
                 .prefix = "",
                 .allowedDomainBitmask = domainToBitmask(domain::platform),
                 .allowedProgTypes = kPlatformAllowedProgTypes,
                 .allowedProgTypesLength = arraysize(kPlatformAllowedProgTypes),
         },
         // Vendor operating system
         {
                 .dir = "/vendor/etc/bpf/",
                 .prefix = "vendor/",
                 .allowedDomainBitmask = domainToBitmask(domain::vendor),
                 .allowedProgTypes = kVendorAllowedProgTypes,
                 .allowedProgTypesLength = arraysize(kVendorAllowedProgTypes),
         },
 };

 int loadAllElfObjects(const android::bpf::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);
             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;
 }

 int 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) {
             const int err = errno;
             ALOGE("Failed to create directory: %s, ret: %s", s.c_str(), std::strerror(err));
             return -err;
         }

         umask(prevUmask);
     }
     return 0;
 }

 // Technically 'value' doesn't need to be newline terminated, but it's best
 // to include a newline to match 'echo "value" > /proc/sys/...foo' behaviour,
 // which is usually how kernel devs test the actual sysctl interfaces.
 int writeProcSysFile(const char *filename, const char *value) {
     android::base::unique_fd fd(open(filename, O_WRONLY | O_CLOEXEC));
     if (fd < 0) {
         const int err = errno;
         ALOGE("open('%s', O_WRONLY | O_CLOEXEC) -> %s", filename, strerror(err));
         return -err;
     }
     int len = strlen(value);
     int v = write(fd, value, len);
     if (v < 0) {
         const int err = errno;
         ALOGE("write('%s', '%s', %d) -> %s", filename, value, len, strerror(err));
         return -err;
     }
     if (v != len) {
         // In practice, due to us only using this for /proc/sys/... files, this can't happen.
         ALOGE("write('%s', '%s', %d) -> short write [%d]", filename, value, len, v);
         return -EINVAL;
     }
     return 0;
 }

 int main(int argc, char** argv) {
     (void)argc;
     android::base::InitLogging(argv, &android::base::KernelLogger);

     // Linux 5.16-rc1 changed the default to 2 (disabled but changeable), but we need 0 (enabled)
     // (this writeFile is known to fail on at least 4.19, but always defaults to 0 on pre-5.13,
     // on 5.13+ it depends on CONFIG_BPF_UNPRIV_DEFAULT_OFF)
     if (writeProcSysFile("/proc/sys/kernel/unprivileged_bpf_disabled", "0\n") &&
         android::bpf::isAtLeastKernelVersion(5, 13, 0)) return 1;

     // Enable the eBPF JIT -- but do note that on 64-bit kernels it is likely
     // already force enabled by the kernel config option BPF_JIT_ALWAYS_ON.
     // (Note: this (open) will fail with ENOENT 'No such file or directory' if
     //  kernel does not have CONFIG_BPF_JIT=y)
     // BPF_JIT is required by R VINTF (which means 4.14/4.19/5.4 kernels),
     // but 4.14/4.19 were released with P & Q, and only 5.4 is new in R+.
     if (writeProcSysFile("/proc/sys/net/core/bpf_jit_enable", "1\n")) return 1;

     // Enable JIT kallsyms export for privileged users only
     // (Note: this (open) will fail with ENOENT 'No such file or directory' if
     //  kernel does not have CONFIG_HAVE_EBPF_JIT=y)
     if (writeProcSysFile("/proc/sys/net/core/bpf_jit_kallsyms", "1\n")) return 1;

     // 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) {
         if (createSysFsBpfSubDir(location.prefix)) return 1;
     }

     // Note: there's no actual src dir for fs_bpf_loader .o's,
     // so it is not listed in 'locations[].prefix'.
     // This is because this is primarily meant for triggering genfscon rules,
     // and as such this will likely always be the case.
     // Thus we need to manually create the /sys/fs/bpf/loader subdirectory.
     if (createSysFsBpfSubDir("loader")) return 1;

     // 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;
         }
     }

     return 0;
 }
	/*
	* 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 "BpfSyscallWrappers.h"
	#include "bpf/BpfUtils.h"

	using android::base::EndsWith;
	using android::bpf::domain;
	using std::string;

	bool exists(const char* const path) {
	int v = access(path, F_OK);
	if (!v) {
	ALOGI("%s exists.", path);
	return true;
	}
	if (errno == ENOENT) return false;
	ALOGE("FATAL: access(%s, F_OK) -> %d [%d:%s]", path, v, errno, strerror(errno));
	abort(); // can only hit this if permissions (likely selinux) are screwed up
	}

	// Networking-related program types are limited to the Tethering Apex
	// to prevent things from breaking due to conflicts on mainline updates
	// (exception made for socket filters, ie. xt_bpf for potential use in iptables,
	// or for attaching to sockets directly)
	constexpr bpf_prog_type kPlatformAllowedProgTypes[] = {
	BPF_PROG_TYPE_KPROBE,
	BPF_PROG_TYPE_PERF_EVENT,
	BPF_PROG_TYPE_SOCKET_FILTER,
	BPF_PROG_TYPE_TRACEPOINT,
	BPF_PROG_TYPE_UNSPEC, // Will be replaced with fuse bpf program type
	};

	// 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,
	};


	const android::bpf::Location locations[] = {
	// Core operating system
	{
	.dir = "/system/etc/bpf/",
	.prefix = "",
	.allowedDomainBitmask = domainToBitmask(domain::platform),
	.allowedProgTypes = kPlatformAllowedProgTypes,
	.allowedProgTypesLength = arraysize(kPlatformAllowedProgTypes),
	},
	// Vendor operating system
	{
	.dir = "/vendor/etc/bpf/",
	.prefix = "vendor/",
	.allowedDomainBitmask = domainToBitmask(domain::vendor),
	.allowedProgTypes = kVendorAllowedProgTypes,
	.allowedProgTypesLength = arraysize(kVendorAllowedProgTypes),
	},
	};

	int loadAllElfObjects(const android::bpf::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);
	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;
	}

	int 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) {
	const int err = errno;
	ALOGE("Failed to create directory: %s, ret: %s", s.c_str(), std::strerror(err));
	return -err;
	}

	umask(prevUmask);
	}
	return 0;
	}

	// Technically 'value' doesn't need to be newline terminated, but it's best
	// to include a newline to match 'echo "value" > /proc/sys/...foo' behaviour,
	// which is usually how kernel devs test the actual sysctl interfaces.
	int writeProcSysFile(const char filename, const char value) {
	android::base::unique_fd fd(open(filename, O_WRONLY \| O_CLOEXEC));
	if (fd < 0) {
	const int err = errno;
	ALOGE("open('%s', O_WRONLY \| O_CLOEXEC) -> %s", filename, strerror(err));
	return -err;
	}
	int len = strlen(value);
	int v = write(fd, value, len);
	if (v < 0) {
	const int err = errno;
	ALOGE("write('%s', '%s', %d) -> %s", filename, value, len, strerror(err));
	return -err;
	}
	if (v != len) {
	// In practice, due to us only using this for /proc/sys/... files, this can't happen.
	ALOGE("write('%s', '%s', %d) -> short write [%d]", filename, value, len, v);
	return -EINVAL;
	}
	return 0;
	}

	int main(int argc, char** argv) {
	(void)argc;
	android::base::InitLogging(argv, &android::base::KernelLogger);

	// Linux 5.16-rc1 changed the default to 2 (disabled but changeable), but we need 0 (enabled)
	// (this writeFile is known to fail on at least 4.19, but always defaults to 0 on pre-5.13,
	// on 5.13+ it depends on CONFIG_BPF_UNPRIV_DEFAULT_OFF)
	if (writeProcSysFile("/proc/sys/kernel/unprivileged_bpf_disabled", "0\n") &&
	android::bpf::isAtLeastKernelVersion(5, 13, 0)) return 1;

	// Enable the eBPF JIT -- but do note that on 64-bit kernels it is likely
	// already force enabled by the kernel config option BPF_JIT_ALWAYS_ON.
	// (Note: this (open) will fail with ENOENT 'No such file or directory' if
	// kernel does not have CONFIG_BPF_JIT=y)
	// BPF_JIT is required by R VINTF (which means 4.14/4.19/5.4 kernels),
	// but 4.14/4.19 were released with P & Q, and only 5.4 is new in R+.
	if (writeProcSysFile("/proc/sys/net/core/bpf_jit_enable", "1\n")) return 1;

	// Enable JIT kallsyms export for privileged users only
	// (Note: this (open) will fail with ENOENT 'No such file or directory' if
	// kernel does not have CONFIG_HAVE_EBPF_JIT=y)
	if (writeProcSysFile("/proc/sys/net/core/bpf_jit_kallsyms", "1\n")) return 1;

	// 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) {
	if (createSysFsBpfSubDir(location.prefix)) return 1;
	}

	// Note: there's no actual src dir for fs_bpf_loader .o's,
	// so it is not listed in 'locations[].prefix'.
	// This is because this is primarily meant for triggering genfscon rules,
	// and as such this will likely always be the case.
	// Thus we need to manually create the /sys/fs/bpf/loader subdirectory.
	if (createSysFsBpfSubDir("loader")) return 1;

	// 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;
	}
	}

	return 0;
	}