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// Copyright 2016 The Bazel Authors. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include "src/main/tools/linux-sandbox-options.h"
#include <errno.h>
#include <sched.h>
#include <stdarg.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/wait.h>
#include <unistd.h>
#include <fstream>
#include <iostream>
#include <memory>
#include <string>
#include <vector>
#include "src/main/tools/logging.h"
#include "src/main/tools/process-tools.h"
using std::ifstream;
using std::unique_ptr;
using std::vector;
struct Options opt;
// Print out a usage error. argc and argv are the argument counter and vector,
// fmt is a format, string for the error message to print.
static void Usage(char *program_name, const char *fmt, ...) {
va_list ap;
va_start(ap, fmt);
vfprintf(stderr, fmt, ap);
va_end(ap);
fprintf(stderr, "\nUsage: %s -- command arg1 @args\n", program_name);
fprintf(stderr,
"\nPossible arguments:\n"
" -W <working-dir> working directory (uses current directory if "
"not specified)\n"
" -T <timeout> timeout after which the child process will be "
"terminated with SIGTERM\n"
" -t <timeout> in case timeout occurs, how long to wait before "
"killing the child with SIGKILL\n"
" -i on receipt of a SIGINT, forward it to the child process as a "
"SIGTERM first and then as a SIGKILL after the -T timeout\n"
" -l <file> redirect stdout to a file\n"
" -L <file> redirect stderr to a file\n"
" -w <file> make a file or directory writable for the sandboxed "
"process\n"
" -e <dir> mount an empty tmpfs on a directory\n"
" -M/-m <source/target> directory to mount inside the sandbox\n"
" Multiple directories can be specified and each of them will be "
"mounted readonly.\n"
" The -M option specifies which directory to mount, the -m option "
"specifies where to\n"
" -S <file> if set, write stats in protobuf format to a file\n"
" -H if set, make hostname in the sandbox equal to 'localhost'\n"
" -N if set, a new network namespace will be created\n"
" -R if set, make the uid/gid be root\n"
" -U if set, make the uid/gid be nobody\n"
" -D if set, debug info will be printed\n"
" -h <sandbox-dir> if set, chroot to sandbox-dir and only "
" mount whats been specified with -M/-m for improved hermeticity. "
" The working-dir should be a folder inside the sandbox-dir\n"
" @FILE read newline-separated arguments from FILE\n"
" -- command to run inside sandbox, followed by arguments\n");
exit(EXIT_FAILURE);
}
static void ValidateIsAbsolutePath(char *path, char *program_name, char flag) {
if (path[0] != '/') {
Usage(program_name, "The -%c option must be used with absolute paths only.",
flag);
}
}
// Parses command line flags from an argv array and puts the results into an
// Options structure passed in as an argument.
static void ParseCommandLine(unique_ptr<vector<char *>> args) {
extern char *optarg;
extern int optind, optopt;
int c;
bool source_specified = false;
while ((c = getopt(args->size(), args->data(),
":W:T:t:il:L:w:e:M:m:S:h:HNRUD")) != -1) {
if (c != 'M' && c != 'm') source_specified = false;
switch (c) {
case 'W':
if (opt.working_dir.empty()) {
ValidateIsAbsolutePath(optarg, args->front(), static_cast<char>(c));
opt.working_dir.assign(optarg);
} else {
Usage(args->front(),
"Multiple working directories (-W) specified, expected one.");
}
break;
case 'T':
if (sscanf(optarg, "%d", &opt.timeout_secs) != 1 ||
opt.timeout_secs < 0) {
Usage(args->front(), "Invalid timeout (-T) value: %s", optarg);
}
break;
case 't':
if (sscanf(optarg, "%d", &opt.kill_delay_secs) != 1 ||
opt.kill_delay_secs < 0) {
Usage(args->front(), "Invalid kill delay (-t) value: %s", optarg);
}
break;
case 'i':
opt.sigint_sends_sigterm = true;
break;
case 'l':
if (opt.stdout_path.empty()) {
opt.stdout_path.assign(optarg);
} else {
Usage(args->front(),
"Cannot redirect stdout to more than one destination.");
}
break;
case 'L':
if (opt.stderr_path.empty()) {
opt.stderr_path.assign(optarg);
} else {
Usage(args->front(),
"Cannot redirect stderr to more than one destination.");
}
break;
case 'w':
ValidateIsAbsolutePath(optarg, args->front(), static_cast<char>(c));
opt.writable_files.emplace_back(optarg);
break;
case 'e':
ValidateIsAbsolutePath(optarg, args->front(), static_cast<char>(c));
opt.tmpfs_dirs.emplace_back(optarg);
break;
case 'M':
ValidateIsAbsolutePath(optarg, args->front(), static_cast<char>(c));
// Add the current source path to both source and target lists
opt.bind_mount_sources.emplace_back(optarg);
opt.bind_mount_targets.emplace_back(optarg);
source_specified = true;
break;
case 'm':
ValidateIsAbsolutePath(optarg, args->front(), static_cast<char>(c));
if (!source_specified) {
Usage(args->front(),
"The -m option must be strictly preceded by an -M option.");
}
opt.bind_mount_targets.pop_back();
opt.bind_mount_targets.emplace_back(optarg);
source_specified = false;
break;
case 'S':
if (opt.stats_path.empty()) {
opt.stats_path.assign(optarg);
} else {
Usage(args->front(),
"Cannot write stats to more than one destination.");
}
break;
case 'h':
opt.hermetic = true;
if (opt.sandbox_root.empty()) {
std::string sandbox_root(optarg);
// Make sure that the sandbox_root path has no trailing slash.
if (sandbox_root.back() == '/') {
ValidateIsAbsolutePath(optarg, args->front(), static_cast<char>(c));
opt.sandbox_root.assign(sandbox_root, 0, sandbox_root.length() - 1);
if (opt.sandbox_root.back() == '/') {
Usage(args->front(),
"Sandbox root path should not have trailing slashes");
}
} else {
opt.sandbox_root.assign(sandbox_root);
}
} else {
Usage(args->front(),
"Multiple sandbox roots (-s) specified, expected one.");
}
break;
case 'H':
opt.fake_hostname = true;
break;
case 'N':
opt.create_netns = true;
break;
case 'R':
if (opt.fake_username) {
Usage(args->front(),
"The -R option cannot be used at the same time us the -U "
"option.");
}
opt.fake_root = true;
break;
case 'U':
if (opt.fake_root) {
Usage(args->front(),
"The -U option cannot be used at the same time us the -R "
"option.");
}
opt.fake_username = true;
break;
case 'D':
opt.debug = true;
break;
case '?':
Usage(args->front(), "Unrecognized argument: -%c (%d)", optopt, optind);
break;
case ':':
Usage(args->front(), "Flag -%c requires an argument", optopt);
break;
}
}
if (!opt.working_dir.empty() && !opt.sandbox_root.empty() &&
opt.working_dir.find(opt.sandbox_root) == std::string::npos) {
Usage(args->front(),
"working-dir %s (-W) should be a "
"subdirectory of sandbox-dir %s (-h)",
opt.working_dir.c_str(), opt.sandbox_root.c_str());
}
if (optind < static_cast<int>(args->size())) {
if (opt.args.empty()) {
opt.args.assign(args->begin() + optind, args->end());
} else {
Usage(args->front(), "Merging commands not supported.");
}
}
}
// Expands a single argument, expanding options @filename to read in the content
// of the file and add it to the list of processed arguments.
static unique_ptr<vector<char *>> ExpandArgument(
unique_ptr<vector<char *>> expanded, char *arg) {
if (arg[0] == '@') {
const char *filename = arg + 1; // strip off the '@'.
ifstream f(filename);
if (!f.is_open()) {
DIE("opening argument file %s failed", filename);
}
for (std::string line; std::getline(f, line);) {
if (line.length() > 0) {
expanded = ExpandArgument(std::move(expanded), strdup(line.c_str()));
}
}
if (f.bad()) {
DIE("error while reading from argument file %s", filename);
}
} else {
expanded->push_back(arg);
}
return expanded;
}
// Pre-processes an argument list, expanding options @filename to read in the
// content of the file and add it to the list of arguments. Stops expanding
// arguments once it encounters "--".
static unique_ptr<vector<char *>> ExpandArguments(const vector<char *> &args) {
unique_ptr<vector<char *>> expanded(new vector<char *>());
expanded->reserve(args.size());
for (auto arg = args.begin(); arg != args.end(); ++arg) {
if (strcmp(*arg, "--") != 0) {
expanded = ExpandArgument(std::move(expanded), *arg);
} else {
expanded->insert(expanded->end(), arg, args.end());
break;
}
}
return expanded;
}
void ParseOptions(int argc, char *argv[]) {
vector<char *> args(argv, argv + argc);
ParseCommandLine(ExpandArguments(args));
if (opt.args.empty()) {
Usage(args.front(), "No command specified.");
}
if (opt.working_dir.empty()) {
char *working_dir = getcwd(nullptr, 0);
if (working_dir == nullptr) {
DIE("getcwd");
}
opt.working_dir = working_dir;
free(working_dir);
}
}