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// SPDX-License-Identifier: CDDL-1.0
/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or https://opensource.org/licenses/CDDL-1.0.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <limits.h>
#include <sys/types.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/wait.h>
#include <fcntl.h>
#include <errno.h>
#include <signal.h>
#include <sched.h>
#define EXECSHELL "/bin/sh"
#define UIDMAP "0 100000 65536"
static int
child_main(int argc, char *argv[], int sync_pipe)
{
char sync_buf;
char cmds[BUFSIZ] = { 0 };
char sep[] = " ";
int i, len;
if (unshare(CLONE_NEWUSER | CLONE_NEWNS) != 0) {
perror("unshare");
return (1);
}
/* tell parent we entered the new namespace */
if (write(sync_pipe, "1", 1) != 1) {
perror("write");
return (1);
}
/* wait for parent to setup the uid mapping */
if (read(sync_pipe, &sync_buf, 1) != 1) {
(void) fprintf(stderr, "user namespace setup failed\n");
return (1);
}
close(sync_pipe);
if (setuid(0) != 0) {
perror("setuid");
return (1);
}
if (setgid(0) != 0) {
perror("setgid");
return (1);
}
len = 0;
for (i = 1; i < argc; i++) {
(void) snprintf(cmds+len, sizeof (cmds)-len,
"%s%s", argv[i], sep);
len += strlen(argv[i]) + strlen(sep);
}
if (execl(EXECSHELL, "sh", "-c", cmds, (char *)NULL) != 0) {
perror("execl: " EXECSHELL);
return (1);
}
return (0);
}
static int
set_idmap(pid_t pid, const char *file)
{
int result = 0;
int mapfd;
char path[PATH_MAX];
(void) snprintf(path, sizeof (path), "/proc/%d/%s", (int)pid, file);
mapfd = open(path, O_WRONLY);
if (mapfd < 0) {
perror("open");
return (errno);
}
if (write(mapfd, UIDMAP, sizeof (UIDMAP)-1) != sizeof (UIDMAP)-1) {
perror("write");
result = (errno);
}
close(mapfd);
return (result);
}
int
main(int argc, char *argv[])
{
char sync_buf;
int result, wstatus;
int syncfd[2];
pid_t child;
if (argc < 2 || strlen(argv[1]) == 0) {
(void) printf("\tUsage: %s <commands> ...\n", argv[0]);
return (1);
}
if (socketpair(AF_UNIX, SOCK_STREAM, 0, syncfd) != 0) {
perror("socketpair");
return (1);
}
child = fork();
if (child == (pid_t)-1) {
perror("fork");
return (1);
}
if (child == 0) {
close(syncfd[0]);
return (child_main(argc, argv, syncfd[1]));
}
close(syncfd[1]);
result = 0;
/* wait for the child to have unshared its namespaces */
if (read(syncfd[0], &sync_buf, 1) != 1) {
perror("read");
kill(child, SIGKILL);
result = 1;
goto reap;
}
/* write uid mapping */
if (set_idmap(child, "uid_map") != 0 ||
set_idmap(child, "gid_map") != 0) {
result = 1;
kill(child, SIGKILL);
goto reap;
}
/* tell the child to proceed */
if (write(syncfd[0], "1", 1) != 1) {
perror("write");
kill(child, SIGKILL);
result = 1;
goto reap;
}
close(syncfd[0]);
reap:
while (waitpid(child, &wstatus, 0) != child)
kill(child, SIGKILL);
if (result == 0)
result = WEXITSTATUS(wstatus);
return (result);
}
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