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// SPDX-License-Identifier: GPL-2.0
/*
* Sandbox itself and execute another program (in a different mount point).
*
* Used by layout1.umount_sandboxer from fs_test.c
*
* Copyright © 2024-2025 Microsoft Corporation
*/
#define _GNU_SOURCE
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/prctl.h>
#include <unistd.h>
#include "wrappers.h"
int main(int argc, char *argv[])
{
struct landlock_ruleset_attr ruleset_attr = {
.scoped = LANDLOCK_SCOPE_SIGNAL,
};
int pipe_child, pipe_parent, ruleset_fd;
char buf;
/*
* The first argument must be the file descriptor number of a pipe.
* The second argument must be the program to execute.
*/
if (argc != 4) {
fprintf(stderr, "Wrong number of arguments (not three)\n");
return 1;
}
pipe_child = atoi(argv[2]);
pipe_parent = atoi(argv[3]);
ruleset_fd =
landlock_create_ruleset(&ruleset_attr, sizeof(ruleset_attr), 0);
if (ruleset_fd < 0) {
perror("Failed to create ruleset");
return 1;
}
if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0)) {
perror("Failed to call prctl()");
return 1;
}
if (landlock_restrict_self(ruleset_fd, 0)) {
perror("Failed to restrict self");
return 1;
}
if (close(ruleset_fd)) {
perror("Failed to close ruleset");
return 1;
}
/* Signals that we are sandboxed. */
errno = 0;
if (write(pipe_child, ".", 1) != 1) {
perror("Failed to write to the second argument");
return 1;
}
/* Waits for the parent to try to umount. */
if (read(pipe_parent, &buf, 1) != 1) {
perror("Failed to write to the third argument");
return 1;
}
/* Shifts arguments. */
argv[0] = argv[1];
argv[1] = argv[2];
argv[2] = argv[3];
argv[3] = NULL;
execve(argv[0], argv, NULL);
perror("Failed to execute the provided binary");
return 1;
}
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