2016-03-03 22:54:15 +08:00
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/*
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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 <unistd.h>
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#include "log.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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2016-09-25 20:30:19 +08:00
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static bool userUidMapSelf(struct nsjconf_t *nsjconf, pid_t pid) {
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2016-03-03 22:54:15 +08:00
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char fname[PATH_MAX];
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char map[128];
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snprintf(fname, sizeof(fname), "/proc/%d/uid_map", pid);
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snprintf(map, sizeof(map), "%lu %lu 1", (unsigned long)nsjconf->inside_uid,
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(unsigned long)nsjconf->outside_uid);
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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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2016-09-25 20:30:19 +08:00
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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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char fname[PATH_MAX];
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char map[128];
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2016-03-03 22:54:15 +08:00
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snprintf(fname, sizeof(fname), "/proc/%d/gid_map", pid);
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snprintf(map, sizeof(map), "%lu %lu 1", (unsigned long)nsjconf->inside_gid,
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(unsigned long)nsjconf->outside_gid);
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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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2016-09-25 20:30:19 +08:00
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// use /usr/bin/newgidmap for writing the uid and gid map
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static bool userGidMapExternal(struct nsjconf_t *nsjconf, pid_t pid) {
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char cmd_buf[1024];
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char *cmd_ptr = cmd_buf;
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size_t len = sizeof(cmd_buf);
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int write_size;
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write_size = snprintf(cmd_ptr, len, "/usr/bin/newgidmap %lu %lu %lu 1",
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(unsigned long)pid,
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(unsigned long)nsjconf->inside_gid,
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(unsigned long)nsjconf->outside_gid);
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if (write_size <= 0 || (size_t) write_size > len) {
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LOG_E("snprintf writing the new{u,g}idmap command failed");
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return false;
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}
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cmd_ptr += write_size;
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len -= write_size;
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struct mapping_t *p;
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TAILQ_FOREACH(p, &nsjconf->gid_mappings, pointers) {
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write_size = snprintf(cmd_ptr, len, " %s %s %s",
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p->inside_id, p->outside_id, p->count);
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if (write_size <= 0 || (size_t) write_size > len) {
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LOG_E("snprintf writing the new{u,g}idmap command failed");
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return false;
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}
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cmd_ptr += write_size;
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len -= write_size;
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}
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if (system(cmd_buf) != 0) {
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LOG_E("system('%s') failed", cmd_buf);
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while(1) ;
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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 and gid map
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static bool userUidMapExternal(struct nsjconf_t *nsjconf, pid_t pid) {
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char cmd_buf[1024];
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char *cmd_ptr = cmd_buf;
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size_t len = sizeof(cmd_buf);
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int write_size;
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write_size = snprintf(cmd_ptr, len, "/usr/bin/newuidmap %lu %lu %lu 1",
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(unsigned long)pid,
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(unsigned long)nsjconf->inside_uid,
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(unsigned long)nsjconf->outside_uid);
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if (write_size <= 0 || (size_t) write_size > len) {
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LOG_E("snprintf writing the new{u,g}idmap command failed");
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return false;
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}
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cmd_ptr += write_size;
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len -= write_size;
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struct mapping_t *p;
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TAILQ_FOREACH(p, &nsjconf->uid_mappings, pointers) {
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write_size = snprintf(cmd_ptr, len, " %s %s %s",
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p->inside_id, p->outside_id, p->count);
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if (write_size <= 0 || (size_t) write_size > len) {
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LOG_E("snprintf writing the new{u,g}idmap command failed");
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return false;
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}
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cmd_ptr += write_size;
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len -= write_size;
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}
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if (system(cmd_buf) != 0) {
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LOG_E("system('%s') failed", cmd_buf);
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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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2016-03-03 22:54:15 +08:00
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bool userInitNsFromParent(struct nsjconf_t * nsjconf, pid_t pid)
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{
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2016-03-04 03:11:32 +08:00
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if (nsjconf->clone_newuser == false) {
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return true;
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}
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2016-03-03 22:54:15 +08:00
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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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