| // 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 "linux-sandbox-options.h" | |
| #include "linux-sandbox-utils.h" | |
| #define DIE(args...) \ | |
| { \ | |
| fprintf(stderr, __FILE__ ":" S__LINE__ ": \"" args); \ | |
| fprintf(stderr, "\": "); \ | |
| perror(NULL); \ | |
| exit(EXIT_FAILURE); \ | |
| } | |
| #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> | |
| 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" | |
| " -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" | |
| " -i <file> make a file or directory inaccessible for the " | |
| "sandboxed process\n" | |
| " -e <dir> mount an empty tmpfs on a directory\n" | |
| " -b <dir> bind mount a file or directory inside the sandbox\n" | |
| " -N if set, a new network namespace will be created\n" | |
| " -R if set, make the uid/gid be root, otherwise use nobody\n" | |
| " -D if set, debug info will be printed\n" | |
| " @FILE read newline-separated arguments from FILE\n" | |
| " -- command to run inside sandbox, followed by arguments\n"); | |
| exit(EXIT_FAILURE); | |
| } | |
| // Child function used by CheckNamespacesSupported() in call to clone(). | |
| static int CheckNamespacesSupportedChild(void *arg) { return 0; } | |
| // Check whether the required namespaces are supported. | |
| static int CheckNamespacesSupported() { | |
| const int kStackSize = 1024 * 1024; | |
| vector<char> child_stack(kStackSize); | |
| pid_t pid = clone(CheckNamespacesSupportedChild, &child_stack.back(), | |
| CLONE_NEWUSER | CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC | | |
| CLONE_NEWNET | CLONE_NEWPID | SIGCHLD, | |
| NULL); | |
| if (pid < 0) { | |
| DIE("pid"); | |
| } | |
| int err; | |
| do { | |
| err = waitpid(pid, NULL, 0); | |
| } while (err < 0 && errno == EINTR); | |
| if (err < 0) { | |
| DIE("waitpid"); | |
| } | |
| return EXIT_SUCCESS; | |
| } | |
| // 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; | |
| while ((c = getopt(args->size(), args->data(), | |
| ":CS:W:T:t:l:L:w:i:e:b:NRD")) != -1) { | |
| switch (c) { | |
| case 'C': | |
| // Shortcut for the "does this system support sandboxing" check. | |
| exit(CheckNamespacesSupported()); | |
| break; | |
| case 'S': | |
| if (opt.sandbox_root_dir == NULL) { | |
| if (optarg[0] != '/') { | |
| Usage(args->front(), | |
| "The -r option must be used with absolute paths only."); | |
| } | |
| opt.sandbox_root_dir = strdup(optarg); | |
| } else { | |
| Usage(args->front(), | |
| "Multiple root directories (-r) specified, expected one."); | |
| } | |
| break; | |
| case 'W': | |
| if (opt.working_dir == NULL) { | |
| if (optarg[0] != '/') { | |
| Usage(args->front(), | |
| "The -W option must be used with absolute paths only."); | |
| } | |
| opt.working_dir = strdup(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 'l': | |
| if (opt.stdout_path == NULL) { | |
| opt.stdout_path = optarg; | |
| } else { | |
| Usage(args->front(), | |
| "Cannot redirect stdout to more than one destination."); | |
| } | |
| break; | |
| case 'L': | |
| if (opt.stderr_path == NULL) { | |
| opt.stderr_path = optarg; | |
| } else { | |
| Usage(args->front(), | |
| "Cannot redirect stderr to more than one destination."); | |
| } | |
| break; | |
| case 'w': | |
| if (optarg[0] != '/') { | |
| Usage(args->front(), | |
| "The -w option must be used with absolute paths only."); | |
| } | |
| opt.writable_files.push_back(strdup(optarg)); | |
| break; | |
| case 'i': | |
| if (optarg[0] != '/') { | |
| Usage(args->front(), | |
| "The -i option must be used with absolute paths only."); | |
| } | |
| opt.inaccessible_files.push_back(strdup(optarg)); | |
| break; | |
| case 'e': | |
| if (optarg[0] != '/') { | |
| Usage(args->front(), | |
| "The -e option must be used with absolute paths only."); | |
| } | |
| opt.tmpfs_dirs.push_back(strdup(optarg)); | |
| break; | |
| case 'b': | |
| if (optarg[0] != '/') { | |
| Usage(args->front(), | |
| "The -b option must be used with absolute paths only."); | |
| } | |
| opt.bind_mounts.push_back(strdup(optarg)); | |
| break; | |
| case 'N': | |
| opt.create_netns = true; | |
| break; | |
| case 'R': | |
| opt.fake_root = 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 (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. | |
| 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 "--". | |
| 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; | |
| } | |
| // Handles parsing all command line flags and populates the global opt struct. | |
| 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."); | |
| } | |
| opt.tmpfs_dirs.push_back("/tmp"); | |
| if (opt.working_dir == NULL) { | |
| opt.working_dir = getcwd(NULL, 0); | |
| } | |
| } |