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/*
* Copyright (c) 2020, Sergey Bugaev <bugaevc@serenityos.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <AK/StringView.h>
#include <LibCore/ArgsParser.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
int main(int argc, char** argv)
{
int flags = -1;
uid_t chroot_user = 0;
gid_t chroot_group = 0;
const char* path = nullptr;
const char* program = "/bin/Shell";
const char* userspec = "0:0";
Core::ArgsParser args_parser;
args_parser.set_general_help(
"Run a program in a chroot sandbox. During execution, the program "
"sees the given path as '/', and cannot access files outside of it.");
args_parser.add_positional_argument(path, "New root directory", "path");
args_parser.add_positional_argument(program, "Program to run", "program", Core::ArgsParser::Required::No);
Core::ArgsParser::Option userspec_option {
true,
"The uid:gid to use",
"userspec",
'u',
"userpec",
[&userspec](const char* s) {
Vector<StringView> parts = StringView(s).split_view(':', true);
if (parts.size() != 2)
return false;
userspec = s;
return true;
}
};
args_parser.add_option(move(userspec_option));
Core::ArgsParser::Option mount_options {
true,
"Mount options",
"options",
'o',
"options",
[&flags](const char* s) {
flags = 0;
Vector<StringView> parts = StringView(s).split_view(',');
for (auto& part : parts) {
if (part == "defaults")
continue;
else if (part == "nodev")
flags |= MS_NODEV;
else if (part == "noexec")
flags |= MS_NOEXEC;
else if (part == "nosuid")
flags |= MS_NOSUID;
else if (part == "ro")
flags |= MS_RDONLY;
else if (part == "remount")
flags |= MS_REMOUNT;
else if (part == "bind")
fprintf(stderr, "Ignoring -o bind, as it doesn't make sense for chroot\n");
else
return false;
}
return true;
}
};
args_parser.add_option(move(mount_options));
args_parser.parse(argc, argv);
if (chroot_with_mount_flags(path, flags) < 0) {
perror("chroot");
return 1;
}
if (chdir("/") < 0) {
perror("chdir(/)");
return 1;
}
// Failed parsing will silently fail open (uid=0; gid=0);
// 0:0 is also the default when no --userspec argument is provided.
auto parts = String(userspec).split(':', true);
chroot_user = (uid_t)strtol(parts[0].characters(), nullptr, 10);
chroot_group = (uid_t)strtol(parts[1].characters(), nullptr, 10);
if (setresgid(chroot_group, chroot_group, chroot_group)) {
perror("setgid");
return 1;
}
if (setresuid(chroot_user, chroot_user, chroot_user)) {
perror("setuid");
return 1;
}
execl(program, program, nullptr);
perror("execl");
return 1;
}
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