libcutils: fs_config read from file
Intention is to read from ${OUT}/system/etc/fs_config_dirs and ${OUT}/system/etc/fs_config_files on host. And /system/etc/fs_config_dirs and /system/etc/config_files on target systems. Bug: 19908228 Change-Id: I0966a94f79a3fae4f7325056c701ea355370f9df
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c01445d2e8
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4e5f71ae72
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@ -19,12 +19,36 @@
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** by the device side of adb.
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*/
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#include <stdint.h>
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#include <string.h>
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#include <sys/stat.h>
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#define LOG_TAG "fs_config"
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#define _GNU_SOURCE
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#include <endian.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <stdbool.h>
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#include <stdint.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/mman.h>
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#include <sys/stat.h>
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#include <sys/types.h>
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#include <cutils/fs.h>
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#include <log/log.h>
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#include <private/android_filesystem_config.h>
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/* The following structure is stored little endian */
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struct fs_path_config_from_file {
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uint16_t len;
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uint16_t mode;
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uint16_t uid;
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uint16_t gid;
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uint64_t capabilities;
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char prefix[];
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} __attribute__((__aligned__(sizeof(uint64_t))));
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/* Rules for directories.
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** These rules are applied based on "first match", so they
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** should start with the most specific path and work their
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@ -61,6 +85,9 @@ static const struct fs_path_config android_dirs[] = {
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** way up to the root. Prefixes ending in * denotes wildcard
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** and will allow partial matches.
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*/
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static const char conf_dir[] = "/system/etc/fs_config_dirs";
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static const char conf_file[] = "/system/etc/fs_config_files";
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static const struct fs_path_config android_files[] = {
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{ 00440, AID_ROOT, AID_SHELL, 0, "system/etc/init.goldfish.rc" },
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{ 00550, AID_ROOT, AID_SHELL, 0, "system/etc/init.goldfish.sh" },
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@ -68,6 +95,8 @@ static const struct fs_path_config android_files[] = {
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{ 00550, AID_DHCP, AID_SHELL, 0, "system/etc/dhcpcd/dhcpcd-run-hooks" },
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{ 00555, AID_ROOT, AID_ROOT, 0, "system/etc/ppp/*" },
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{ 00555, AID_ROOT, AID_ROOT, 0, "system/etc/rc.*" },
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{ 00444, AID_ROOT, AID_ROOT, 0, conf_dir + 1 },
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{ 00444, AID_ROOT, AID_ROOT, 0, conf_file + 1 },
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{ 00644, AID_SYSTEM, AID_SYSTEM, 0, "data/app/*" },
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{ 00644, AID_MEDIA_RW, AID_MEDIA_RW, 0, "data/media/*" },
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{ 00644, AID_SYSTEM, AID_SYSTEM, 0, "data/app-private/*" },
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@ -101,30 +130,114 @@ static const struct fs_path_config android_files[] = {
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{ 00644, AID_ROOT, AID_ROOT, 0, 0 },
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};
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static int fs_config_open(int dir)
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{
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int fd = -1;
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const char *out = getenv("OUT");
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if (out && *out) {
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char *name = NULL;
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asprintf(&name, "%s%s", out, dir ? conf_dir : conf_file);
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if (name) {
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fd = TEMP_FAILURE_RETRY(open(name, O_RDONLY));
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free(name);
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}
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}
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if (fd < 0) {
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fd = TEMP_FAILURE_RETRY(open(dir ? conf_dir : conf_file, O_RDONLY));
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}
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return fd;
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}
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static bool fs_config_cmp(bool dir, const char *prefix, size_t len,
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const char *path, size_t plen)
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{
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if (dir) {
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if (plen < len) {
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return false;
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}
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} else {
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/* If name ends in * then allow partial matches. */
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if (prefix[len - 1] == '*') {
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return !strncmp(prefix, path, len - 1);
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}
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if (plen != len) {
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return false;
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}
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}
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return !strncmp(prefix, path, len);
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}
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void fs_config(const char *path, int dir,
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unsigned *uid, unsigned *gid, unsigned *mode, uint64_t *capabilities)
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{
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const struct fs_path_config *pc;
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int plen;
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struct stat st;
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void *address = NULL;
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int fd = fs_config_open(dir);
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if ((fd >= 0)
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&& (TEMP_FAILURE_RETRY(fstat(fd, &st)) >= 0)
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&& (size_t)st.st_size) {
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address = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
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if (address == MAP_FAILED) {
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address = NULL;
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}
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} else if (fd >= 0) {
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close(fd);
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}
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if (path[0] == '/') {
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path++;
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}
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pc = dir ? android_dirs : android_files;
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plen = strlen(path);
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for(; pc->prefix; pc++){
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int len = strlen(pc->prefix);
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if (dir) {
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if(plen < len) continue;
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if(!strncmp(pc->prefix, path, len)) break;
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continue;
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if (address) {
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const struct fs_path_config_from_file *p = (const struct fs_path_config_from_file *)
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address;
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const char *end = (const char *)address + st.st_size;
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const struct fs_path_config_from_file *e = (const struct fs_path_config_from_file *)
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(end - sizeof(*p));
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for (; p < e; p = (const struct fs_path_config_from_file *)(((const char *)p) + le16toh(p->len))) {
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ssize_t len, remainder = le16toh(p->len) - sizeof(*p);
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if (remainder <= 0) {
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ALOGE("%s is truncated", dir ? conf_dir : conf_file);
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p = e;
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break;
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}
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len = (const char *)e - (const char *)p;
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if (remainder > len) {
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remainder = len;
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}
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len = strnlen(p->prefix, remainder);
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if (len >= remainder) { /* missing a terminating null */
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ALOGE("%s is corrupted", dir ? conf_dir : conf_file);
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p = e;
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break;
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}
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if (fs_config_cmp(dir, p->prefix, len, path, plen)) {
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break;
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}
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}
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/* If name ends in * then allow partial matches. */
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if (pc->prefix[len -1] == '*') {
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if(!strncmp(pc->prefix, path, len - 1)) break;
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} else if (plen == len){
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if(!strncmp(pc->prefix, path, len)) break;
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if (p < e) {
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*uid = le16toh(p->uid);
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*gid = le16toh(p->gid);
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*mode = (*mode & (~07777)) | le16toh(p->mode);
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*capabilities = le64toh(p->capabilities);
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}
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munmap(address, st.st_size);
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close(fd);
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if (p < e) {
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return;
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}
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}
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pc = dir ? android_dirs : android_files;
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for(; pc->prefix; pc++){
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if (fs_config_cmp(dir, pc->prefix, strlen(pc->prefix), path, plen)) {
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break;
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}
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}
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*uid = pc->uid;
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