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platform_system_core/libcutils/fs_config.cpp

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/*
* Copyright (C) 2007 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.
*/
// This file is used to define the properties of the filesystem
// images generated by build tools (mkbootfs and mkyaffs2image) and
// by the device side of adb.
#define LOG_TAG "fs_config"
#include <errno.h>
#include <fcntl.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <log/log.h>
#include <private/android_filesystem_config.h>
#include <private/fs_config.h>
#include <utils/Compat.h>
#ifndef O_BINARY
#define O_BINARY 0
#endif
// My kingdom for <endian.h>
static inline uint16_t get2LE(const uint8_t* src) {
return src[0] | (src[1] << 8);
}
static inline uint64_t get8LE(const uint8_t* src) {
uint32_t low, high;
low = src[0] | (src[1] << 8) | (src[2] << 16) | (src[3] << 24);
high = src[4] | (src[5] << 8) | (src[6] << 16) | (src[7] << 24);
return ((uint64_t)high << 32) | (uint64_t)low;
}
#define ALIGN(x, alignment) (((x) + ((alignment)-1)) & ~((alignment)-1))
// Rules for directories.
// These rules are applied based on "first match", so they
// should start with the most specific path and work their
// way up to the root.
static const struct fs_path_config android_dirs[] = {
// clang-format off
{ 00770, AID_SYSTEM, AID_CACHE, 0, "cache" },
{ 00500, AID_ROOT, AID_ROOT, 0, "config" },
{ 00771, AID_SYSTEM, AID_SYSTEM, 0, "data/app" },
{ 00771, AID_SYSTEM, AID_SYSTEM, 0, "data/app-private" },
{ 00771, AID_SYSTEM, AID_SYSTEM, 0, "data/app-ephemeral" },
{ 00771, AID_ROOT, AID_ROOT, 0, "data/dalvik-cache" },
{ 00771, AID_SYSTEM, AID_SYSTEM, 0, "data/data" },
{ 00771, AID_SHELL, AID_SHELL, 0, "data/local/tmp" },
{ 00771, AID_SHELL, AID_SHELL, 0, "data/local" },
{ 00770, AID_DHCP, AID_DHCP, 0, "data/misc/dhcp" },
{ 00771, AID_SHARED_RELRO, AID_SHARED_RELRO, 0, "data/misc/shared_relro" },
{ 01771, AID_SYSTEM, AID_MISC, 0, "data/misc" },
{ 00775, AID_MEDIA_RW, AID_MEDIA_RW, 0, "data/media/Music" },
{ 00775, AID_MEDIA_RW, AID_MEDIA_RW, 0, "data/media" },
{ 00750, AID_ROOT, AID_SHELL, 0, "data/nativetest" },
{ 00750, AID_ROOT, AID_SHELL, 0, "data/nativetest64" },
{ 00775, AID_ROOT, AID_ROOT, 0, "data/preloads" },
{ 00771, AID_SYSTEM, AID_SYSTEM, 0, "data" },
{ 00755, AID_ROOT, AID_SYSTEM, 0, "mnt" },
{ 00755, AID_ROOT, AID_ROOT, 0, "root" },
{ 00750, AID_ROOT, AID_SHELL, 0, "sbin" },
{ 00777, AID_ROOT, AID_ROOT, 0, "sdcard" },
{ 00751, AID_ROOT, AID_SDCARD_R, 0, "storage" },
{ 00755, AID_ROOT, AID_SHELL, 0, "system/bin" },
{ 00755, AID_ROOT, AID_ROOT, 0, "system/etc/ppp" },
{ 00755, AID_ROOT, AID_SHELL, 0, "system/vendor" },
{ 00755, AID_ROOT, AID_SHELL, 0, "system/xbin" },
{ 00755, AID_ROOT, AID_SHELL, 0, "vendor" },
{ 00755, AID_ROOT, AID_ROOT, 0, 0 },
// clang-format on
};
#ifndef __ANDROID_VNDK__
auto __for_testing_only__android_dirs = android_dirs;
#endif
// Rules for files.
// These rules are applied based on "first match", so they
// should start with the most specific path and work their
// way up to the root. Prefixes ending in * denotes wildcard
// and will allow partial matches.
static const char sys_conf_dir[] = "/system/etc/fs_config_dirs";
static const char sys_conf_file[] = "/system/etc/fs_config_files";
// No restrictions are placed on the vendor and oem file-system config files,
// although the developer is advised to restrict the scope to the /vendor or
// oem/ file-system since the intent is to provide support for customized
// portions of a separate vendor.img or oem.img. Has to remain open so that
// customization can also land on /system/vendor, /system/oem or /system/odm.
// We expect build-time checking or filtering when constructing the associated
// fs_config_* files (see build/tools/fs_config/fs_config_generate.c)
static const char ven_conf_dir[] = "/vendor/etc/fs_config_dirs";
static const char ven_conf_file[] = "/vendor/etc/fs_config_files";
static const char oem_conf_dir[] = "/oem/etc/fs_config_dirs";
static const char oem_conf_file[] = "/oem/etc/fs_config_files";
static const char odm_conf_dir[] = "/odm/etc/fs_config_dirs";
static const char odm_conf_file[] = "/odm/etc/fs_config_files";
static const char* conf[][2] = {
{sys_conf_file, sys_conf_dir},
{ven_conf_file, ven_conf_dir},
{oem_conf_file, oem_conf_dir},
{odm_conf_file, odm_conf_dir},
};
static const struct fs_path_config android_files[] = {
// clang-format off
{ 00644, AID_SYSTEM, AID_SYSTEM, 0, "data/app/*" },
{ 00644, AID_SYSTEM, AID_SYSTEM, 0, "data/app-ephemeral/*" },
{ 00644, AID_SYSTEM, AID_SYSTEM, 0, "data/app-private/*" },
{ 00644, AID_APP, AID_APP, 0, "data/data/*" },
{ 00644, AID_MEDIA_RW, AID_MEDIA_RW, 0, "data/media/*" },
{ 00640, AID_ROOT, AID_SHELL, 0, "data/nativetest/tests.txt" },
{ 00640, AID_ROOT, AID_SHELL, 0, "data/nativetest64/tests.txt" },
{ 00750, AID_ROOT, AID_SHELL, 0, "data/nativetest/*" },
{ 00750, AID_ROOT, AID_SHELL, 0, "data/nativetest64/*" },
{ 00600, AID_ROOT, AID_ROOT, 0, "default.prop" },
{ 00600, AID_ROOT, AID_ROOT, 0, "odm/build.prop" },
{ 00600, AID_ROOT, AID_ROOT, 0, "odm/default.prop" },
{ 00444, AID_ROOT, AID_ROOT, 0, odm_conf_dir + 1 },
{ 00444, AID_ROOT, AID_ROOT, 0, odm_conf_file + 1 },
{ 00444, AID_ROOT, AID_ROOT, 0, oem_conf_dir + 1 },
{ 00444, AID_ROOT, AID_ROOT, 0, oem_conf_file + 1 },
{ 00750, AID_ROOT, AID_SHELL, 0, "sbin/fs_mgr" },
{ 00755, AID_ROOT, AID_SHELL, 0, "system/bin/crash_dump32" },
{ 00755, AID_ROOT, AID_SHELL, 0, "system/bin/crash_dump64" },
{ 00755, AID_ROOT, AID_SHELL, 0, "system/bin/debuggerd" },
{ 00750, AID_ROOT, AID_ROOT, 0, "system/bin/install-recovery.sh" },
{ 00700, AID_ROOT, AID_ROOT, 0, "system/bin/secilc" },
{ 00750, AID_ROOT, AID_ROOT, 0, "system/bin/uncrypt" },
{ 00600, AID_ROOT, AID_ROOT, 0, "system/build.prop" },
{ 00444, AID_ROOT, AID_ROOT, 0, sys_conf_dir + 1 },
{ 00444, AID_ROOT, AID_ROOT, 0, sys_conf_file + 1 },
{ 00440, AID_ROOT, AID_SHELL, 0, "system/etc/init.goldfish.rc" },
{ 00550, AID_ROOT, AID_SHELL, 0, "system/etc/init.goldfish.sh" },
{ 00550, AID_ROOT, AID_SHELL, 0, "system/etc/init.ril" },
{ 00555, AID_ROOT, AID_ROOT, 0, "system/etc/ppp/*" },
{ 00555, AID_ROOT, AID_ROOT, 0, "system/etc/rc.*" },
{ 00440, AID_ROOT, AID_ROOT, 0, "system/etc/recovery.img" },
{ 00600, AID_ROOT, AID_ROOT, 0, "vendor/build.prop" },
{ 00600, AID_ROOT, AID_ROOT, 0, "vendor/default.prop" },
{ 00444, AID_ROOT, AID_ROOT, 0, ven_conf_dir + 1 },
{ 00444, AID_ROOT, AID_ROOT, 0, ven_conf_file + 1 },
// the following two files are INTENTIONALLY set-uid, but they
// are NOT included on user builds.
{ 06755, AID_ROOT, AID_ROOT, 0, "system/xbin/procmem" },
{ 04750, AID_ROOT, AID_SHELL, 0, "system/xbin/su" },
// the following files have enhanced capabilities and ARE included
// in user builds.
{ 00700, AID_SYSTEM, AID_SHELL, CAP_MASK_LONG(CAP_BLOCK_SUSPEND),
"system/bin/inputflinger" },
{ 00550, AID_LOGD, AID_LOGD, CAP_MASK_LONG(CAP_SYSLOG) |
CAP_MASK_LONG(CAP_AUDIT_CONTROL) |
CAP_MASK_LONG(CAP_SETGID),
"system/bin/logd" },
{ 00750, AID_ROOT, AID_SHELL, CAP_MASK_LONG(CAP_SETUID) |
CAP_MASK_LONG(CAP_SETGID),
"system/bin/run-as" },
// Support FIFO scheduling mode in SurfaceFlinger.
{ 00755, AID_SYSTEM, AID_GRAPHICS, CAP_MASK_LONG(CAP_SYS_NICE),
"system/bin/surfaceflinger" },
// Support hostapd administering a network interface.
{ 00755, AID_WIFI, AID_WIFI, CAP_MASK_LONG(CAP_NET_ADMIN) |
CAP_MASK_LONG(CAP_NET_RAW),
"system/bin/hostapd" },
// Support Bluetooth legacy hal accessing /sys/class/rfkill
// Support RT scheduling in Bluetooth
{ 00700, AID_BLUETOOTH, AID_BLUETOOTH, CAP_MASK_LONG(CAP_NET_ADMIN) |
CAP_MASK_LONG(CAP_SYS_NICE),
"vendor/bin/hw/android.hardware.bluetooth@1.0-service" },
// Support wifi_hal_legacy administering a network interface.
{ 00755, AID_WIFI, AID_WIFI, CAP_MASK_LONG(CAP_NET_ADMIN) |
CAP_MASK_LONG(CAP_NET_RAW),
"vendor/bin/hw/android.hardware.wifi@1.0-service" },
// A non-privileged zygote that spawns isolated processes for web rendering.
{ 0750, AID_ROOT, AID_ROOT, CAP_MASK_LONG(CAP_SETUID) |
CAP_MASK_LONG(CAP_SETGID) |
CAP_MASK_LONG(CAP_SETPCAP),
"system/bin/webview_zygote32" },
{ 0750, AID_ROOT, AID_ROOT, CAP_MASK_LONG(CAP_SETUID) |
CAP_MASK_LONG(CAP_SETGID) |
CAP_MASK_LONG(CAP_SETPCAP),
"system/bin/webview_zygote64" },
// generic defaults
{ 00755, AID_ROOT, AID_ROOT, 0, "bin/*" },
{ 00640, AID_ROOT, AID_SHELL, 0, "fstab.*" },
{ 00750, AID_ROOT, AID_SHELL, 0, "init*" },
{ 00750, AID_ROOT, AID_SHELL, 0, "sbin/*" },
{ 00755, AID_ROOT, AID_SHELL, 0, "system/bin/*" },
{ 00755, AID_ROOT, AID_ROOT, 0, "system/lib/valgrind/*" },
{ 00755, AID_ROOT, AID_ROOT, 0, "system/lib64/valgrind/*" },
{ 00755, AID_ROOT, AID_SHELL, 0, "system/xbin/*" },
{ 00755, AID_ROOT, AID_SHELL, 0, "vendor/bin/*" },
{ 00755, AID_ROOT, AID_SHELL, 0, "vendor/xbin/*" },
{ 00644, AID_ROOT, AID_ROOT, 0, 0 },
// clang-format on
};
#ifndef __ANDROID_VNDK__
auto __for_testing_only__android_files = android_files;
#endif
static size_t strip(const char* path, size_t len, const char suffix[]) {
if (len < strlen(suffix)) return len;
if (strncmp(path + len - strlen(suffix), suffix, strlen(suffix))) return len;
return len - strlen(suffix);
}
static int fs_config_open(int dir, int which, const char* target_out_path) {
int fd = -1;
if (target_out_path && *target_out_path) {
// target_out_path is the path to the directory holding content of
// system partition but as we cannot guarantee it ends with '/system'
// or with or without a trailing slash, need to strip them carefully.
char* name = NULL;
size_t len = strlen(target_out_path);
len = strip(target_out_path, len, "/");
len = strip(target_out_path, len, "/system");
if (asprintf(&name, "%.*s%s", (int)len, target_out_path, conf[which][dir]) != -1) {
fd = TEMP_FAILURE_RETRY(open(name, O_RDONLY | O_BINARY));
free(name);
}
}
if (fd < 0) {
fd = TEMP_FAILURE_RETRY(open(conf[which][dir], O_RDONLY | O_BINARY));
}
return fd;
}
// if path is "vendor/<stuff>", "oem/<stuff>" or "odm/<stuff>"
static bool is_partition(const char* path, size_t len) {
static const char* partitions[] = {"vendor/", "oem/", "odm/"};
for (size_t i = 0; i < (sizeof(partitions) / sizeof(partitions[0])); ++i) {
size_t plen = strlen(partitions[i]);
if (len <= plen) continue;
if (!strncmp(path, partitions[i], plen)) return true;
}
return false;
}
// alias prefixes of "<partition>/<stuff>" to "system/<partition>/<stuff>" or
// "system/<partition>/<stuff>" to "<partition>/<stuff>"
static bool prefix_cmp(const char* prefix, const char* path, size_t len) {
if (!strncmp(prefix, path, len)) return true;
static const char system[] = "system/";
if (!strncmp(path, system, strlen(system))) {
path += strlen(system);
} else if (len <= strlen(system)) {
return false;
} else if (strncmp(prefix, system, strlen(system))) {
return false;
} else {
prefix += strlen(system);
len -= strlen(system);
}
return is_partition(prefix, len) && !strncmp(prefix, path, len);
}
static bool fs_config_cmp(bool dir, const char* prefix, size_t len, const char* path, size_t plen) {
if (dir) {
if (plen < len) {
return false;
}
} else {
// If name ends in * then allow partial matches.
if (prefix[len - 1] == '*') {
return prefix_cmp(prefix, path, len - 1);
}
if (plen != len) {
return false;
}
}
return prefix_cmp(prefix, path, len);
}
void fs_config(const char* path, int dir, const char* target_out_path, unsigned* uid, unsigned* gid,
unsigned* mode, uint64_t* capabilities) {
const struct fs_path_config* pc;
size_t which, plen;
if (path[0] == '/') {
path++;
}
plen = strlen(path);
for (which = 0; which < (sizeof(conf) / sizeof(conf[0])); ++which) {
struct fs_path_config_from_file header;
int fd = fs_config_open(dir, which, target_out_path);
if (fd < 0) continue;
while (TEMP_FAILURE_RETRY(read(fd, &header, sizeof(header))) == sizeof(header)) {
char* prefix;
uint16_t host_len = get2LE((const uint8_t*)&header.len);
ssize_t len, remainder = host_len - sizeof(header);
if (remainder <= 0) {
ALOGE("%s len is corrupted", conf[which][dir]);
break;
}
prefix = static_cast<char*>(calloc(1, remainder));
if (!prefix) {
ALOGE("%s out of memory", conf[which][dir]);
break;
}
if (TEMP_FAILURE_RETRY(read(fd, prefix, remainder)) != remainder) {
free(prefix);
ALOGE("%s prefix is truncated", conf[which][dir]);
break;
}
len = strnlen(prefix, remainder);
if (len >= remainder) { // missing a terminating null
free(prefix);
ALOGE("%s is corrupted", conf[which][dir]);
break;
}
if (fs_config_cmp(dir, prefix, len, path, plen)) {
free(prefix);
close(fd);
*uid = get2LE((const uint8_t*)&(header.uid));
*gid = get2LE((const uint8_t*)&(header.gid));
*mode = (*mode & (~07777)) | get2LE((const uint8_t*)&(header.mode));
*capabilities = get8LE((const uint8_t*)&(header.capabilities));
return;
}
free(prefix);
}
close(fd);
}
for (pc = dir ? android_dirs : android_files; pc->prefix; pc++) {
if (fs_config_cmp(dir, pc->prefix, strlen(pc->prefix), path, plen)) {
break;
}
}
*uid = pc->uid;
*gid = pc->gid;
*mode = (*mode & (~07777)) | pc->mode;
*capabilities = pc->capabilities;
}
ssize_t fs_config_generate(char* buffer, size_t length, const struct fs_path_config* pc) {
struct fs_path_config_from_file* p = (struct fs_path_config_from_file*)buffer;
size_t len = ALIGN(sizeof(*p) + strlen(pc->prefix) + 1, sizeof(uint64_t));
if ((length < len) || (len > UINT16_MAX)) {
return -ENOSPC;
}
memset(p, 0, len);
uint16_t host_len = len;
p->len = get2LE((const uint8_t*)&host_len);
p->mode = get2LE((const uint8_t*)&(pc->mode));
p->uid = get2LE((const uint8_t*)&(pc->uid));
p->gid = get2LE((const uint8_t*)&(pc->gid));
p->capabilities = get8LE((const uint8_t*)&(pc->capabilities));
strcpy(p->prefix, pc->prefix);
return len;
}
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