2017-12-11 20:03:05 +01:00
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/* su_daemon.c - The entrypoint for su, connect to daemon and send correct info
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2017-04-14 21:21:31 +02:00
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*/
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2017-07-07 19:12:47 +02:00
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#define _GNU_SOURCE
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2018-10-04 10:59:51 +02:00
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2017-04-14 21:21:31 +02:00
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#include <unistd.h>
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#include <pthread.h>
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#include <stdlib.h>
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#include <fcntl.h>
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#include <string.h>
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#include <signal.h>
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2018-10-04 10:59:51 +02:00
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#include <pwd.h>
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2017-04-14 21:21:31 +02:00
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#include <sys/socket.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <sys/wait.h>
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#include "magisk.h"
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#include "daemon.h"
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#include "utils.h"
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#include "su.h"
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#include "pts.h"
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2018-09-27 06:09:59 +02:00
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#include "selinux.h"
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2017-04-14 21:21:31 +02:00
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2017-05-29 12:54:33 +02:00
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#define TIMEOUT 3
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2018-10-04 05:31:15 +02:00
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#define LOCK_CACHE() pthread_mutex_lock(&cache_lock)
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#define LOCK_INFO() pthread_mutex_lock(&info->lock)
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#define UNLOCK_CACHE() pthread_mutex_unlock(&cache_lock)
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2018-10-04 10:59:51 +02:00
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#define UNLOCK_INFO() pthread_mutex_unlock(&info->lock)
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2017-07-16 09:31:40 +02:00
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2018-10-04 05:31:15 +02:00
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static pthread_mutex_t cache_lock = PTHREAD_MUTEX_INITIALIZER;
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static struct su_info *cache;
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2017-05-29 12:54:33 +02:00
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2018-06-13 17:04:57 +02:00
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static void *info_collector(void *node) {
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struct su_info *info = node;
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while (1) {
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2017-05-29 12:54:33 +02:00
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sleep(1);
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2018-10-04 05:31:15 +02:00
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if (info->life) {
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LOCK_CACHE();
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if (--info->life == 0 && cache && info->uid == cache->uid)
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cache = NULL;
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UNLOCK_CACHE();
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2017-05-29 12:54:33 +02:00
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}
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2018-10-04 05:31:15 +02:00
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if (!info->life && !info->ref) {
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2018-06-13 17:04:57 +02:00
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pthread_mutex_destroy(&info->lock);
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free(info);
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return NULL;
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2017-05-29 12:54:33 +02:00
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}
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}
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2017-05-07 21:08:34 +02:00
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}
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2017-04-15 20:28:12 +02:00
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2018-06-12 22:33:32 +02:00
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static void database_check(struct su_info *info) {
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int uid = info->uid;
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sqlite3 *db = get_magiskdb();
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if (db) {
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get_db_settings(db, -1, &info->dbs);
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get_db_strings(db, -1, &info->str);
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// Check multiuser settings
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2018-10-04 07:49:52 +02:00
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switch (DB_SET(info, SU_MULTIUSER_MODE)) {
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2018-06-12 22:33:32 +02:00
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case MULTIUSER_MODE_OWNER_ONLY:
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if (info->uid / 100000) {
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uid = -1;
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info->access = NO_SU_ACCESS;
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}
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break;
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case MULTIUSER_MODE_OWNER_MANAGED:
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uid = info->uid % 100000;
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break;
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case MULTIUSER_MODE_USER:
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default:
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break;
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}
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if (uid > 0)
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get_uid_policy(db, uid, &info->access);
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sqlite3_close(db);
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}
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// We need to check our manager
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if (info->access.log || info->access.notify)
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2018-10-04 07:49:52 +02:00
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validate_manager(DB_STR(info, SU_MANAGER), uid / 100000, &info->mgr_st);
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2018-06-12 22:33:32 +02:00
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}
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2017-05-29 12:54:33 +02:00
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2018-06-12 22:33:32 +02:00
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static struct su_info *get_su_info(unsigned uid) {
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2018-10-04 05:31:15 +02:00
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struct su_info *info;
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int cache_miss = 0;
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2017-05-29 12:54:33 +02:00
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2018-10-04 05:31:15 +02:00
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LOCK_CACHE();
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2017-05-29 12:54:33 +02:00
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2018-10-04 05:31:15 +02:00
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if (cache && cache->uid == uid) {
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info = cache;
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} else {
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cache_miss = 1;
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2018-10-04 07:49:52 +02:00
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info = xcalloc(1, sizeof(*info));
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2018-06-12 22:33:32 +02:00
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info->uid = uid;
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info->dbs = DEFAULT_DB_SETTINGS;
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info->access = DEFAULT_SU_ACCESS;
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2017-05-29 12:54:33 +02:00
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pthread_mutex_init(&info->lock, NULL);
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2018-10-04 05:31:15 +02:00
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cache = info;
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2018-06-13 17:04:57 +02:00
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}
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// Update the cache status
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2018-10-04 05:31:15 +02:00
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info->life = TIMEOUT;
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2018-06-13 17:04:57 +02:00
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++info->ref;
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2018-10-04 05:31:15 +02:00
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// Start a thread to maintain the cache
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2018-06-13 17:04:57 +02:00
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if (cache_miss) {
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pthread_t thread;
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xpthread_create(&thread, NULL, info_collector, info);
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pthread_detach(thread);
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2017-05-29 12:54:33 +02:00
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}
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2018-10-04 05:31:15 +02:00
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UNLOCK_CACHE();
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2017-05-29 12:54:33 +02:00
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2017-07-16 09:31:40 +02:00
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LOGD("su: request from uid=[%d] (#%d)\n", info->uid, ++info->count);
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2017-05-29 12:54:33 +02:00
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2017-07-16 09:31:40 +02:00
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// Lock before the policy is determined
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2018-10-04 05:31:15 +02:00
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LOCK_INFO();
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2017-07-16 09:31:40 +02:00
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2018-06-12 22:33:32 +02:00
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if (info->access.policy == QUERY) {
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// Not cached, get data from database
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database_check(info);
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// Check su access settings
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2018-10-04 07:49:52 +02:00
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switch (DB_SET(info, ROOT_ACCESS)) {
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2018-06-12 22:33:32 +02:00
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case ROOT_ACCESS_DISABLED:
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2018-10-04 20:41:48 +02:00
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LOGW("Root access is disabled!\n");
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2018-06-12 22:33:32 +02:00
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info->access = NO_SU_ACCESS;
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break;
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case ROOT_ACCESS_ADB_ONLY:
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if (info->uid != UID_SHELL) {
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2018-10-04 20:41:48 +02:00
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LOGW("Root access limited to ADB only!\n");
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2018-06-12 22:33:32 +02:00
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info->access = NO_SU_ACCESS;
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}
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break;
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case ROOT_ACCESS_APPS_ONLY:
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if (info->uid == UID_SHELL) {
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2018-10-04 20:41:48 +02:00
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LOGW("Root access is disabled for ADB!\n");
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2018-06-12 22:33:32 +02:00
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info->access = NO_SU_ACCESS;
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}
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break;
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case ROOT_ACCESS_APPS_AND_ADB:
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default:
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break;
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2017-05-29 12:54:33 +02:00
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}
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2018-06-12 22:33:32 +02:00
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// If it's the manager, allow it silently
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2018-10-04 07:49:52 +02:00
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if ((info->uid % 100000) == (info->mgr_st.st_uid % 100000))
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2018-06-12 22:33:32 +02:00
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info->access = SILENT_SU_ACCESS;
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// Allow if it's root
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if (info->uid == UID_ROOT)
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info->access = SILENT_SU_ACCESS;
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2017-05-29 12:54:33 +02:00
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2018-06-12 22:33:32 +02:00
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// If still not determined, check if manager exists
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2018-10-04 07:49:52 +02:00
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if (info->access.policy == QUERY && DB_STR(info, SU_MANAGER)[0] == '\0')
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2018-06-12 22:33:32 +02:00
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info->access = NO_SU_ACCESS;
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2017-05-29 12:54:33 +02:00
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}
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2018-10-04 10:59:51 +02:00
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// If still not determined, ask manager
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if (info->access.policy == QUERY) {
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// Create random socket
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struct sockaddr_un addr;
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int sockfd = create_rand_socket(&addr);
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// Connect manager
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app_connect(addr.sun_path + 1, info);
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int fd = socket_accept(sockfd, 60);
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2018-10-04 21:06:13 +02:00
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if (fd < 0) {
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info->access.policy = DENY;
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} else {
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socket_send_request(fd, info);
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int ret = read_int_be(fd);
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info->access.policy = ret < 0 ? DENY : ret;
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close(fd);
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}
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2018-10-04 10:59:51 +02:00
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close(sockfd);
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}
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// Unlock
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UNLOCK_INFO();
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2018-06-12 22:33:32 +02:00
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return info;
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}
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2018-10-04 10:59:51 +02:00
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static void populate_environment(struct su_request *req) {
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struct passwd *pw;
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if (req->keepenv)
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return;
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pw = getpwuid(req->uid);
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if (pw) {
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setenv("HOME", pw->pw_dir, 1);
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if (req->shell)
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setenv("SHELL", req->shell, 1);
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else
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setenv("SHELL", DEFAULT_SHELL, 1);
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if (req->login || req->uid) {
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setenv("USER", pw->pw_name, 1);
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setenv("LOGNAME", pw->pw_name, 1);
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}
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}
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}
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static void set_identity(unsigned uid) {
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/*
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* Set effective uid back to root, otherwise setres[ug]id will fail
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* if uid isn't root.
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*/
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if (seteuid(0)) {
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PLOGE("seteuid (root)");
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}
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if (setresgid(uid, uid, uid)) {
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PLOGE("setresgid (%u)", uid);
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}
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if (setresuid(uid, uid, uid)) {
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PLOGE("setresuid (%u)", uid);
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}
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}
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void su_daemon_handler(int client, struct ucred *credential) {
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LOGD("su: request from client: %d\n", client);
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struct su_info *info = get_su_info(credential->uid);
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// Fail fast
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if (info->access.policy == DENY && !info->access.log && !info->access.notify) {
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write_int(client, DENY);
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return;
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}
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/* Fork a new process, the child process will need to setsid,
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* open a pseudo-terminal if needed, and will eventually run exec
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* The parent process will wait for the result and
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* send the return code back to our client
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*/
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int child = xfork();
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if (child) {
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// Decrement reference count
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--info->ref;
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// Wait result
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LOGD("su: waiting child: [%d]\n", child);
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int status, code;
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if (waitpid(child, &status, 0) > 0)
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code = WEXITSTATUS(status);
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else
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code = -1;
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LOGD("su: return code: [%d]\n", code);
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write(client, &code, sizeof(code));
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close(client);
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return;
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}
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LOGD("su: fork handler\n");
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struct su_context ctx = {
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.info = info,
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.pid = credential->pid
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};
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2017-04-14 21:21:31 +02:00
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// Become session leader
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xsetsid();
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2017-12-18 06:12:06 +01:00
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// Migrate environment from client
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char path[32], buf[4096];
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2018-10-04 10:59:51 +02:00
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snprintf(path, sizeof(path), "/proc/%d/cwd", ctx.pid);
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xreadlink(path, buf, sizeof(buf));
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chdir(buf);
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snprintf(path, sizeof(path), "/proc/%d/environ", ctx.pid);
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2017-12-18 06:12:06 +01:00
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memset(buf, 0, sizeof(buf));
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int fd = open(path, O_RDONLY);
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read(fd, buf, sizeof(buf));
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2018-10-04 10:59:51 +02:00
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close(fd);
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2017-12-18 06:12:06 +01:00
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clearenv();
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for (size_t pos = 0; buf[pos];) {
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putenv(buf + pos);
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pos += strlen(buf + pos) + 1;
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}
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2018-10-04 10:59:51 +02:00
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// Read su_request
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2018-10-04 20:41:48 +02:00
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xxread(client, &ctx.req, 4 * sizeof(unsigned));
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2018-10-04 10:59:51 +02:00
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ctx.req.shell = read_string(client);
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ctx.req.command = read_string(client);
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2017-04-14 21:21:31 +02:00
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// Get pts_slave
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char *pts_slave = read_string(client);
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2018-06-12 22:33:32 +02:00
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// The FDs for each of the streams
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2017-04-15 20:28:12 +02:00
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int infd = recv_fd(client);
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int outfd = recv_fd(client);
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int errfd = recv_fd(client);
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2017-05-07 21:08:34 +02:00
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int ptsfd = -1;
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2017-04-15 20:28:12 +02:00
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if (pts_slave[0]) {
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2018-06-26 12:45:51 +02:00
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LOGD("su: pts_slave=[%s]\n", pts_slave);
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2018-06-12 22:33:32 +02:00
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// Check pts_slave file is owned by daemon_from_uid
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struct stat st;
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xstat(pts_slave, &st);
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2017-04-15 20:28:12 +02:00
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2018-06-12 22:33:32 +02:00
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// If caller is not root, ensure the owner of pts_slave is the caller
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2018-10-04 10:59:51 +02:00
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if(st.st_uid != info->uid && info->uid != 0) {
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2017-04-15 20:28:12 +02:00
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LOGE("su: Wrong permission of pts_slave");
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2018-10-04 10:59:51 +02:00
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info->access.policy = DENY;
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exit(1);
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2017-04-15 20:28:12 +02:00
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}
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2018-08-02 14:29:18 +02:00
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// Set our pts_slave to devpts, same restriction as adb shell
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lsetfilecon(pts_slave, "u:object_r:devpts:s0");
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2017-04-15 20:28:12 +02:00
|
|
|
// Opening the TTY has to occur after the
|
|
|
|
// fork() and setsid() so that it becomes
|
|
|
|
// our controlling TTY and not the daemon's
|
2017-05-07 21:08:34 +02:00
|
|
|
ptsfd = xopen(pts_slave, O_RDWR);
|
2017-04-15 20:28:12 +02:00
|
|
|
|
2018-10-04 10:59:51 +02:00
|
|
|
if (infd < 0)
|
|
|
|
infd = ptsfd;
|
|
|
|
if (outfd < 0)
|
2017-04-15 20:28:12 +02:00
|
|
|
outfd = ptsfd;
|
2018-10-04 10:59:51 +02:00
|
|
|
if (errfd < 0)
|
2017-04-15 20:28:12 +02:00
|
|
|
errfd = ptsfd;
|
2017-04-14 21:21:31 +02:00
|
|
|
}
|
|
|
|
|
|
|
|
free(pts_slave);
|
|
|
|
|
|
|
|
// Swap out stdin, stdout, stderr
|
2017-04-15 20:28:12 +02:00
|
|
|
xdup2(infd, STDIN_FILENO);
|
|
|
|
xdup2(outfd, STDOUT_FILENO);
|
|
|
|
xdup2(errfd, STDERR_FILENO);
|
2017-04-14 21:21:31 +02:00
|
|
|
|
2017-05-07 21:08:34 +02:00
|
|
|
close(ptsfd);
|
|
|
|
|
2018-08-02 14:29:18 +02:00
|
|
|
// ack and close
|
|
|
|
write_int(client, 0);
|
|
|
|
close(client);
|
|
|
|
|
2018-10-04 10:59:51 +02:00
|
|
|
// Handle namespaces
|
2018-10-04 20:41:48 +02:00
|
|
|
if (ctx.req.mount_master)
|
|
|
|
DB_SET(info, SU_MNT_NS) = NAMESPACE_MODE_GLOBAL;
|
2018-10-04 10:59:51 +02:00
|
|
|
switch (DB_SET(info, SU_MNT_NS)) {
|
|
|
|
case NAMESPACE_MODE_GLOBAL:
|
|
|
|
LOGD("su: use global namespace\n");
|
|
|
|
break;
|
|
|
|
case NAMESPACE_MODE_REQUESTER:
|
|
|
|
LOGD("su: use namespace of pid=[%d]\n", ctx.pid);
|
|
|
|
if (switch_mnt_ns(ctx.pid)) {
|
|
|
|
LOGD("su: setns failed, fallback to isolated\n");
|
|
|
|
xunshare(CLONE_NEWNS);
|
|
|
|
}
|
|
|
|
break;
|
|
|
|
case NAMESPACE_MODE_ISOLATE:
|
|
|
|
LOGD("su: use new isolated namespace\n");
|
|
|
|
xunshare(CLONE_NEWNS);
|
|
|
|
break;
|
2018-06-26 12:45:51 +02:00
|
|
|
}
|
|
|
|
|
2018-10-04 20:41:48 +02:00
|
|
|
if (info->access.notify || info->access.log)
|
|
|
|
app_log(&ctx);
|
|
|
|
|
|
|
|
if (info->access.policy == ALLOW) {
|
2018-10-04 10:59:51 +02:00
|
|
|
char* argv[] = { NULL, NULL, NULL, NULL };
|
2018-06-26 12:45:51 +02:00
|
|
|
|
2018-10-04 20:41:48 +02:00
|
|
|
argv[0] = ctx.req.login ? "-" : ctx.req.shell;
|
2018-06-26 12:45:51 +02:00
|
|
|
|
2018-10-04 10:59:51 +02:00
|
|
|
if (ctx.req.command[0]) {
|
|
|
|
argv[1] = "-c";
|
|
|
|
argv[2] = ctx.req.command;
|
|
|
|
}
|
2017-04-14 21:21:31 +02:00
|
|
|
|
2018-10-04 10:59:51 +02:00
|
|
|
// Setup shell
|
|
|
|
umask(022);
|
|
|
|
populate_environment(&ctx.req);
|
|
|
|
set_identity(ctx.req.uid);
|
2017-04-14 21:21:31 +02:00
|
|
|
|
2018-10-04 10:59:51 +02:00
|
|
|
execvp(ctx.req.shell, argv);
|
|
|
|
fprintf(stderr, "Cannot execute %s: %s\n", ctx.req.shell, strerror(errno));
|
|
|
|
PLOGE("exec");
|
|
|
|
exit(EXIT_FAILURE);
|
2017-04-15 20:28:12 +02:00
|
|
|
} else {
|
2018-10-04 10:59:51 +02:00
|
|
|
LOGW("su: request rejected (%u->%u)", info->uid, ctx.req.uid);
|
2018-06-13 12:14:23 +02:00
|
|
|
fprintf(stderr, "%s\n", strerror(EACCES));
|
2018-10-04 10:59:51 +02:00
|
|
|
exit(EXIT_FAILURE);
|
2018-06-13 12:14:23 +02:00
|
|
|
}
|
2017-04-14 21:21:31 +02:00
|
|
|
}
|
2018-10-04 10:59:51 +02:00
|
|
|
|