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platform_system_core/libcutils/fs_config.c

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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"
#define _GNU_SOURCE
#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 <utils/Compat.h>
#ifndef O_BINARY
#define O_BINARY 0
#endif
/* The following structure is stored little endian */
struct fs_path_config_from_file {
uint16_t len;
uint16_t mode;
uint16_t uid;
uint16_t gid;
uint64_t capabilities;
char prefix[];
} __attribute__((__aligned__(sizeof(uint64_t))));
/* 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[] = {
{ 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" },
{ 01771, AID_SYSTEM, AID_MISC, 0, "data/misc" },
{ 00770, AID_DHCP, AID_DHCP, 0, "data/misc/dhcp" },
{ 00771, AID_SHARED_RELRO, AID_SHARED_RELRO, 0, "data/misc/shared_relro" },
{ 00775, AID_MEDIA_RW, AID_MEDIA_RW, 0, "data/media" },
{ 00775, AID_MEDIA_RW, AID_MEDIA_RW, 0, "data/media/Music" },
{ 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" },
{ 00751, AID_ROOT, AID_SDCARD_R, 0, "storage" },
{ 00755, AID_ROOT, AID_SHELL, 0, "system/bin" },
{ 00755, AID_ROOT, AID_SHELL, 0, "system/vendor" },
{ 00755, AID_ROOT, AID_SHELL, 0, "system/xbin" },
{ 00755, AID_ROOT, AID_ROOT, 0, "system/etc/ppp" },
{ 00755, AID_ROOT, AID_SHELL, 0, "vendor" },
{ 00777, AID_ROOT, AID_ROOT, 0, "sdcard" },
{ 00755, AID_ROOT, AID_ROOT, 0, 0 },
};
/* 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 conf_dir[] = "/system/etc/fs_config_dirs";
static const char conf_file[] = "/system/etc/fs_config_files";
static const struct fs_path_config android_files[] = {
{ 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" },
{ 00444, AID_ROOT, AID_ROOT, 0, conf_dir + 1 },
{ 00444, AID_ROOT, AID_ROOT, 0, conf_file + 1 },
{ 00644, AID_SYSTEM, AID_SYSTEM, 0, "data/app/*" },
{ 00644, AID_MEDIA_RW, AID_MEDIA_RW, 0, "data/media/*" },
{ 00644, AID_SYSTEM, AID_SYSTEM, 0, "data/app-private/*" },
{ 00644, AID_SYSTEM, AID_SYSTEM, 0, "data/app-ephemeral/*" },
{ 00644, AID_APP, AID_APP, 0, "data/data/*" },
{ 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/*" },
/* the following two files are INTENTIONALLY set-uid, but they
* are NOT included on user builds. */
{ 04750, AID_ROOT, AID_SHELL, 0, "system/xbin/su" },
{ 06755, AID_ROOT, AID_ROOT, 0, "system/xbin/procmem" },
/* the following files have enhanced capabilities and ARE included in user builds. */
{ 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" },
{ 00700, AID_SYSTEM, AID_SHELL, CAP_MASK_LONG(CAP_BLOCK_SUSPEND),
"system/bin/inputflinger" },
/* 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),
"vendor/bin/hostapd" },
/* 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" },
/* Support Bluetooth legacy hal accessing /sys/class/rfkill */
{ 00700, AID_BLUETOOTH, AID_BLUETOOTH, CAP_MASK_LONG(CAP_NET_ADMIN),
"vendor/bin/hw/android.hardware.bluetooth@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" },
{ 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" },
{ 00700, AID_ROOT, AID_ROOT, 0, "system/bin/secilc" },
{ 00750, AID_ROOT, AID_ROOT, 0, "system/bin/uncrypt" },
{ 00750, AID_ROOT, AID_ROOT, 0, "system/bin/install-recovery.sh" },
{ 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, "system/vendor/bin/*" },
{ 00755, AID_ROOT, AID_SHELL, 0, "system/vendor/xbin/*" },
{ 00755, AID_ROOT, AID_SHELL, 0, "vendor/bin/*" },
{ 00755, AID_ROOT, AID_SHELL, 0, "vendor/xbin/*" },
{ 00750, AID_ROOT, AID_SHELL, 0, "sbin/*" },
{ 00755, AID_ROOT, AID_ROOT, 0, "bin/*" },
{ 00750, AID_ROOT, AID_SHELL, 0, "init*" },
{ 00750, AID_ROOT, AID_SHELL, 0, "sbin/fs_mgr" },
{ 00640, AID_ROOT, AID_SHELL, 0, "fstab.*" },
{ 00600, AID_ROOT, AID_ROOT, 0, "system/build.prop" },
{ 00600, AID_ROOT, AID_ROOT, 0, "vendor/build.prop" },
{ 00600, AID_ROOT, AID_ROOT, 0, "odm/build.prop" },
{ 00600, AID_ROOT, AID_ROOT, 0, "default.prop" },
{ 00600, AID_ROOT, AID_ROOT, 0, "vendor/default.prop" },
{ 00600, AID_ROOT, AID_ROOT, 0, "odm/default.prop" },
{ 00644, AID_ROOT, AID_ROOT, 0, 0 },
};
static int fs_config_open(int dir, 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 guaranty it ends with '/system' we need this below skip_len logic */
char *name = NULL;
int target_out_path_len = strlen(target_out_path);
int skip_len = strlen("/system");
if (target_out_path[target_out_path_len] == '/') {
skip_len++;
}
if (asprintf(&name, "%s%s", target_out_path, (dir ? conf_dir : conf_file) + skip_len) != -1) {
fd = TEMP_FAILURE_RETRY(open(name, O_RDONLY | O_BINARY));
free(name);
}
}
if (fd < 0) {
fd = TEMP_FAILURE_RETRY(open(dir ? conf_dir : conf_file, O_RDONLY | O_BINARY));
}
return fd;
}
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 !strncmp(prefix, path, len - 1);
}
if (plen != len) {
return false;
}
}
return !strncmp(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;
int fd, plen;
if (path[0] == '/') {
path++;
}
plen = strlen(path);
fd = fs_config_open(dir, target_out_path);
if (fd >= 0) {
struct fs_path_config_from_file header;
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", dir ? conf_dir : conf_file);
break;
}
prefix = calloc(1, remainder);
if (!prefix) {
ALOGE("%s out of memory", dir ? conf_dir : conf_file);
break;
}
if (TEMP_FAILURE_RETRY(read(fd, prefix, remainder)) != remainder) {
free(prefix);
ALOGE("%s prefix is truncated", dir ? conf_dir : conf_file);
break;
}
len = strnlen(prefix, remainder);
if (len >= remainder) { /* missing a terminating null */
free(prefix);
ALOGE("%s is corrupted", dir ? conf_dir : conf_file);
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);
}
pc = dir ? android_dirs : android_files;
for(; 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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