224 lines
5.7 KiB
C
224 lines
5.7 KiB
C
/*
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nsjail - CLONE_NEWUSER routines
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-----------------------------------------
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Copyright 2014 Google Inc. All Rights Reserved.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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#include "user.h"
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#include <errno.h>
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#include <fcntl.h>
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#include <grp.h>
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#include <stdbool.h>
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#include <stddef.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/syscall.h>
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#include <unistd.h>
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#include "log.h"
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#include "subproc.h"
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#include "util.h"
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static bool userSetGroups(pid_t pid)
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{
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/*
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* No need to write 'deny' to /proc/pid/setgroups if our euid==0, as writing to uid_map/gid_map
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* will succeed anyway
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*/
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if (geteuid() == 0) {
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return true;
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}
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char fname[PATH_MAX];
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snprintf(fname, sizeof(fname), "/proc/%d/setgroups", pid);
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const char *denystr = "deny";
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if (utilWriteBufToFile(fname, denystr, strlen(denystr), O_WRONLY) == false) {
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LOG_E("utilWriteBufToFile('%s', '%s') failed", fname, denystr);
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return false;
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}
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return true;
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}
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static bool userUidMapSelf(struct nsjconf_t *nsjconf, pid_t pid)
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{
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char fname[PATH_MAX];
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snprintf(fname, sizeof(fname), "/proc/%d/uid_map", pid);
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char map[4096] = {[0] = '\0' };
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struct idmap_t *p;
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TAILQ_FOREACH(p, &nsjconf->uids, pointers) {
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utilSSnPrintf(map, sizeof(map), "%lu %lu 1\n", (unsigned long)p->inside_id,
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(unsigned long)p->outside_id);
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}
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LOG_D("Writing '%s' to '%s'", map, fname);
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if (utilWriteBufToFile(fname, map, strlen(map), O_WRONLY) == false) {
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LOG_E("utilWriteBufToFile('%s', '%s') failed", fname, map);
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return false;
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}
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return true;
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}
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static bool userGidMapSelf(struct nsjconf_t *nsjconf, pid_t pid)
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{
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char fname[PATH_MAX];
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snprintf(fname, sizeof(fname), "/proc/%d/gid_map", pid);
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char map[4096] = {[0] = '\0' };
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struct idmap_t *p;
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TAILQ_FOREACH(p, &nsjconf->gids, pointers) {
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utilSSnPrintf(map, sizeof(map), "%lu %lu 1\n", (unsigned long)p->inside_id,
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(unsigned long)p->outside_id);
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}
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LOG_D("Writing '%s' to '%s'", map, fname);
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if (utilWriteBufToFile(fname, map, strlen(map), O_WRONLY) == false) {
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LOG_E("utilWriteBufToFile('%s', '%s') failed", fname, map);
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return false;
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}
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return true;
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}
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/* Use /usr/bin/newgidmap for writing the gid map */
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static bool userGidMapExternal(struct nsjconf_t *nsjconf, pid_t pid UNUSED)
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{
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char pid_str[128];
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snprintf(pid_str, sizeof(pid_str), "%d", (int)pid);
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const char *argv[1024] = { "/usr/bin/newgidmap", pid_str };
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size_t argv_idx = 2;
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struct mapping_t *p;
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TAILQ_FOREACH(p, &nsjconf->gid_mappings, pointers) {
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if (argv_idx >= ARRAYSIZE(argv)) {
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LOG_W("Number of arguments to '/usr/bin/newgidmap' too big");
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return false;
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}
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argv[argv_idx++] = p->inside_id;
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argv[argv_idx++] = p->outside_id;
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argv[argv_idx++] = p->count;
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}
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argv[argv_idx++] = NULL;
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if (subprocSystem(argv, environ) != 0) {
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LOG_E("'/usr/bin/newgidmap' failed");
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return false;
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}
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return true;
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}
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/* Use /usr/bin/newuidmap for writing the uid map */
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static bool userUidMapExternal(struct nsjconf_t *nsjconf, pid_t pid UNUSED)
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{
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char pid_str[128];
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snprintf(pid_str, sizeof(pid_str), "%d", (int)pid);
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const char *argv[1024] = { "/usr/bin/newuidmap", pid_str };
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size_t argv_idx = 2;
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struct mapping_t *p;
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TAILQ_FOREACH(p, &nsjconf->uid_mappings, pointers) {
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if (argv_idx >= ARRAYSIZE(argv)) {
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LOG_W("Number of arguments to '/usr/bin/newuidmap' too big");
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return false;
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}
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argv[argv_idx++] = p->inside_id;
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argv[argv_idx++] = p->outside_id;
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argv[argv_idx++] = p->count;
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}
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argv[argv_idx++] = NULL;
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if (subprocSystem(argv, environ) != 0) {
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LOG_E("'/usr/bin/newuidmap' failed");
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return false;
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}
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return true;
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}
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static bool userUidGidMap(struct nsjconf_t *nsjconf, pid_t pid)
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{
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if (TAILQ_EMPTY(&nsjconf->gid_mappings)) {
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if (!userGidMapSelf(nsjconf, pid)) {
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return false;
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}
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} else {
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if (!userGidMapExternal(nsjconf, pid)) {
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return false;
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}
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}
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if (TAILQ_EMPTY(&nsjconf->uid_mappings)) {
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return userUidMapSelf(nsjconf, pid);
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} else {
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return userUidMapExternal(nsjconf, pid);
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}
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}
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bool userInitNsFromParent(struct nsjconf_t * nsjconf, pid_t pid)
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{
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if (nsjconf->clone_newuser == false) {
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return true;
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}
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if (userSetGroups(pid) == false) {
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return false;
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}
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if (userUidGidMap(nsjconf, pid) == false) {
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return false;
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}
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return true;
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}
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bool userInitNsFromChild(struct nsjconf_t * nsjconf)
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{
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/*
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* Best effort because of /proc/self/setgroups
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*/
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LOG_D("setgroups(0, NULL)");
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gid_t *group_list = NULL;
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if (setgroups(0, group_list) == -1) {
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PLOG_D("setgroups(NULL) failed");
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}
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LOG_D("setresgid(%d, %d, %d)", TAILQ_FIRST(&nsjconf->gids)->inside_id,
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TAILQ_FIRST(&nsjconf->gids)->inside_id, TAILQ_FIRST(&nsjconf->gids)->inside_id);
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if (syscall
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(__NR_setresgid, TAILQ_FIRST(&nsjconf->gids)->inside_id,
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TAILQ_FIRST(&nsjconf->gids)->inside_id,
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TAILQ_FIRST(&nsjconf->gids)->inside_id) == -1) {
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PLOG_E("setresgid(%u)", TAILQ_FIRST(&nsjconf->gids)->inside_id);
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return false;
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}
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LOG_D("setresuid(%d, %d, %d)", TAILQ_FIRST(&nsjconf->uids)->inside_id,
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TAILQ_FIRST(&nsjconf->uids)->inside_id, TAILQ_FIRST(&nsjconf->uids)->inside_id);
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if (syscall
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(__NR_setresuid, TAILQ_FIRST(&nsjconf->uids)->inside_id,
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TAILQ_FIRST(&nsjconf->uids)->inside_id,
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TAILQ_FIRST(&nsjconf->uids)->inside_id) == -1) {
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PLOG_E("setresuid(%u)", TAILQ_FIRST(&nsjconf->uids)->inside_id);
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return false;
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}
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return true;
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}
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