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Diffstat (limited to 'libcutils/fs_config.c')
| -rw-r--r-- | libcutils/fs_config.c | 273 |
1 files changed, 273 insertions, 0 deletions
diff --git a/libcutils/fs_config.c b/libcutils/fs_config.c new file mode 100644 index 0000000..9f8023e --- /dev/null +++ b/libcutils/fs_config.c @@ -0,0 +1,273 @@ +/* + * 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" }, + { 00771, AID_SYSTEM, AID_SYSTEM, 0, "data/app" }, + { 00771, AID_SYSTEM, AID_SYSTEM, 0, "data/app-private" }, + { 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" }, + { 00771, AID_SYSTEM, AID_SYSTEM, 0, "data" }, + { 00750, AID_ROOT, AID_SHELL, 0, "sbin" }, + { 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" }, + { 00550, AID_DHCP, AID_SHELL, 0, "system/etc/dhcpcd/dhcpcd-run-hooks" }, + { 00555, AID_ROOT, AID_ROOT, 0, "system/etc/ppp/*" }, + { 00555, AID_ROOT, AID_ROOT, 0, "system/etc/rc.*" }, + { 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_APP, AID_APP, 0, "data/data/*" }, + + /* the following five 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/librank" }, + { 06755, AID_ROOT, AID_ROOT, 0, "system/xbin/procrank" }, + { 06755, AID_ROOT, AID_ROOT, 0, "system/xbin/procmem" }, + { 04770, AID_ROOT, AID_RADIO, 0, "system/bin/pppd-ril" }, + + /* the following files have enhanced capabilities and ARE included in user builds. */ + { 00750, AID_ROOT, AID_SHELL, (1ULL << CAP_SETUID) | (1ULL << CAP_SETGID), "system/bin/run-as" }, + { 00700, AID_SYSTEM, AID_SHELL, (1ULL << CAP_BLOCK_SUSPEND), "system/bin/inputflinger" }, + + { 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, "vendor/bin/*" }, + { 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.*" }, + { 00644, AID_ROOT, AID_ROOT, 0, 0 }, +}; + +static int fs_config_open(int dir) +{ + int fd = -1; + + const char *out = getenv("OUT"); + if (out && *out) { + char *name = NULL; + asprintf(&name, "%s%s", out, dir ? conf_dir : conf_file); + if (name) { + 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, + 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); + 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; +} |