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
This commit is contained in:
Mark Salyzyn 2015-04-01 09:24:22 -07:00
parent c01445d2e8
commit 4e5f71ae72
1 changed files with 128 additions and 15 deletions

View File

@ -19,12 +19,36 @@
** by the device side of adb.
*/
#include <stdint.h>
#include <string.h>
#include <sys/stat.h>
#define LOG_TAG "fs_config"
#define _GNU_SOURCE
#include <endian.h>
#include <errno.h>
#include <fcntl.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <cutils/fs.h>
#include <log/log.h>
#include <private/android_filesystem_config.h>
/* 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))));
/* Rules for directories.
** These rules are applied based on "first match", so they
** should start with the most specific path and work their
@ -61,6 +85,9 @@ static const struct fs_path_config android_dirs[] = {
** 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" },
@ -68,6 +95,8 @@ static const struct fs_path_config android_files[] = {
{ 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/*" },
@ -101,30 +130,114 @@ static const struct fs_path_config android_files[] = {
{ 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));
free(name);
}
}
if (fd < 0) {
fd = TEMP_FAILURE_RETRY(open(dir ? conf_dir : conf_file, O_RDONLY));
}
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 plen;
struct stat st;
void *address = NULL;
int fd = fs_config_open(dir);
if ((fd >= 0)
&& (TEMP_FAILURE_RETRY(fstat(fd, &st)) >= 0)
&& (size_t)st.st_size) {
address = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
if (address == MAP_FAILED) {
address = NULL;
}
} else if (fd >= 0) {
close(fd);
}
if (path[0] == '/') {
path++;
}
pc = dir ? android_dirs : android_files;
plen = strlen(path);
for(; pc->prefix; pc++){
int len = strlen(pc->prefix);
if (dir) {
if(plen < len) continue;
if(!strncmp(pc->prefix, path, len)) break;
continue;
if (address) {
const struct fs_path_config_from_file *p = (const struct fs_path_config_from_file *)
address;
const char *end = (const char *)address + st.st_size;
const struct fs_path_config_from_file *e = (const struct fs_path_config_from_file *)
(end - sizeof(*p));
for (; p < e; p = (const struct fs_path_config_from_file *)(((const char *)p) + le16toh(p->len))) {
ssize_t len, remainder = le16toh(p->len) - sizeof(*p);
if (remainder <= 0) {
ALOGE("%s is truncated", dir ? conf_dir : conf_file);
p = e;
break;
}
len = (const char *)e - (const char *)p;
if (remainder > len) {
remainder = len;
}
len = strnlen(p->prefix, remainder);
if (len >= remainder) { /* missing a terminating null */
ALOGE("%s is corrupted", dir ? conf_dir : conf_file);
p = e;
break;
}
if (fs_config_cmp(dir, p->prefix, len, path, plen)) {
break;
}
}
/* If name ends in * then allow partial matches. */
if (pc->prefix[len -1] == '*') {
if(!strncmp(pc->prefix, path, len - 1)) break;
} else if (plen == len){
if(!strncmp(pc->prefix, path, len)) break;
if (p < e) {
*uid = le16toh(p->uid);
*gid = le16toh(p->gid);
*mode = (*mode & (~07777)) | le16toh(p->mode);
*capabilities = le64toh(p->capabilities);
}
munmap(address, st.st_size);
close(fd);
if (p < e) {
return;
}
}
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;