diff --git a/libcutils/fs_config.c b/libcutils/fs_config.c index 659f614b8..bdb24dc3e 100644 --- a/libcutils/fs_config.c +++ b/libcutils/fs_config.c @@ -19,12 +19,50 @@ ** by the device side of adb. */ -#include -#include -#include +#define LOG_TAG "fs_config" +#define _GNU_SOURCE + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include +#include #include +/* 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 */ +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; +} + /* 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 +99,9 @@ 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 +109,8 @@ 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 +144,116 @@ 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)); + uint16_t host_len = sizeof(*p); + for (; p < e; p = (const struct fs_path_config_from_file *)(((const char *)p) + host_len)) { + host_len = get2LE((const uint8_t *)&(p->len)); + ssize_t len, remainder = host_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 = get2LE((const uint8_t *)&(p->uid)); + *gid = get2LE((const uint8_t *)&(p->gid)); + *mode = (*mode & (~07777)) | get2LE((const uint8_t *)&(p->mode)); + *capabilities = get8LE((const uint8_t *)&(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;