int sandbox(void* sandbox_arg) { // Get rid of unused parameter warning (void)sandbox_arg; pid_t child_pid = getpid(); if (arg_debug) printf("Initializing child process\n"); // close each end of the unused pipes close(parent_to_child_fds[1]); close(child_to_parent_fds[0]); // wait for parent to do base setup wait_for_other(parent_to_child_fds[0]); if (arg_debug && child_pid == 1) printf("PID namespace installed\n"); //**************************** // set hostname //**************************** if (cfg.hostname) { if (sethostname(cfg.hostname, strlen(cfg.hostname)) < 0) errExit("sethostname"); } //**************************** // mount namespace //**************************** // mount events are not forwarded between the host the sandbox if (mount(NULL, "/", NULL, MS_SLAVE | MS_REC, NULL) < 0) { chk_chroot(); } //**************************** // log sandbox data //**************************** if (cfg.name) fs_logger2("sandbox name:", cfg.name); fs_logger2int("sandbox pid:", (int) sandbox_pid); if (cfg.chrootdir) fs_logger("sandbox filesystem: chroot"); else if (arg_overlay) fs_logger("sandbox filesystem: overlay"); else fs_logger("sandbox filesystem: local"); fs_logger("install mount namespace"); //**************************** // netfilter etc. //**************************** if (arg_netfilter && any_bridge_configured()) { // assuming by default the client filter netfilter(arg_netfilter_file); } if (arg_netfilter6 && any_bridge_configured()) { // assuming by default the client filter netfilter6(arg_netfilter6_file); } // load IBUS env variables if (arg_nonetwork || any_bridge_configured() || any_interface_configured()) { // do nothing - there are problems with ibus version 1.5.11 } else env_ibus_load(); // grab a copy of cp command fs_build_cp_command(); // trace pre-install if (arg_trace || arg_tracelog) fs_trace_preload(); //**************************** // configure filesystem //**************************** #ifdef HAVE_SECCOMP int enforce_seccomp = 0; #endif #ifdef HAVE_CHROOT if (cfg.chrootdir) { fs_chroot(cfg.chrootdir); // redo cp command fs_build_cp_command(); // force caps and seccomp if not started as root if (getuid() != 0) { // force default seccomp inside the chroot, no keep or drop list // the list build on top of the default drop list is kept intact arg_seccomp = 1; #ifdef HAVE_SECCOMP enforce_seccomp = 1; #endif if (cfg.seccomp_list_drop) { free(cfg.seccomp_list_drop); cfg.seccomp_list_drop = NULL; } if (cfg.seccomp_list_keep) { free(cfg.seccomp_list_keep); cfg.seccomp_list_keep = NULL; } // disable all capabilities if (arg_caps_default_filter || arg_caps_list) fprintf(stderr, "Warning: all capabilities disabled for a regular user during chroot\n"); arg_caps_drop_all = 1; // drop all supplementary groups; /etc/group file inside chroot // is controlled by a regular usr arg_nogroups = 1; if (!arg_quiet) printf("Dropping all Linux capabilities and enforcing default seccomp filter\n"); } else arg_seccomp = 1; //**************************** // trace pre-install, this time inside chroot //**************************** if (arg_trace || arg_tracelog) fs_trace_preload(); } else #endif if (arg_overlay) fs_overlayfs(); else fs_basic_fs(); //**************************** // set hostname in /etc/hostname //**************************** if (cfg.hostname) { fs_hostname(cfg.hostname); } //**************************** // private mode //**************************** if (arg_private) { if (cfg.home_private) // --private= fs_private_homedir(); else // --private fs_private(); } if (arg_private_dev) fs_private_dev(); if (arg_private_etc) { fs_private_etc_list(); // create /etc/ld.so.preload file again if (arg_trace || arg_tracelog) fs_trace_preload(); } if (arg_private_bin) fs_private_bin_list(); if (arg_private_tmp) fs_private_tmp(); //**************************** // apply the profile file //**************************** if (cfg.profile) { // apply all whitelist commands ... fs_whitelist(); // ... followed by blacklist commands fs_blacklist(); } //**************************** // install trace //**************************** if (arg_trace || arg_tracelog) fs_trace(); //**************************** // update /proc, /dev, /boot directorymy //**************************** fs_proc_sys_dev_boot(); //**************************** // --nosound and fix for pulseaudio 7.0 //**************************** if (arg_nosound) pulseaudio_disable(); else pulseaudio_init(); //**************************** // networking //**************************** if (arg_nonetwork) { net_if_up("lo"); if (arg_debug) printf("Network namespace enabled, only loopback interface available\n"); } else if (any_bridge_configured() || any_interface_configured()) { // configure lo and eth0...eth3 net_if_up("lo"); if (mac_not_zero(cfg.bridge0.macsandbox)) net_config_mac(cfg.bridge0.devsandbox, cfg.bridge0.macsandbox); sandbox_if_up(&cfg.bridge0); if (mac_not_zero(cfg.bridge1.macsandbox)) net_config_mac(cfg.bridge1.devsandbox, cfg.bridge1.macsandbox); sandbox_if_up(&cfg.bridge1); if (mac_not_zero(cfg.bridge2.macsandbox)) net_config_mac(cfg.bridge2.devsandbox, cfg.bridge2.macsandbox); sandbox_if_up(&cfg.bridge2); if (mac_not_zero(cfg.bridge3.macsandbox)) net_config_mac(cfg.bridge3.devsandbox, cfg.bridge3.macsandbox); sandbox_if_up(&cfg.bridge3); // add a default route if (cfg.defaultgw) { // set the default route if (net_add_route(0, 0, cfg.defaultgw)) fprintf(stderr, "Warning: cannot configure default route\n"); } // enable interfaces if (cfg.interface0.configured && cfg.interface0.ip) { if (arg_debug) printf("Configuring %d.%d.%d.%d address on interface %s\n", PRINT_IP(cfg.interface0.ip), cfg.interface0.dev); net_if_ip(cfg.interface0.dev, cfg.interface0.ip, cfg.interface0.mask, cfg.interface0.mtu); net_if_up(cfg.interface0.dev); } if (cfg.interface1.configured && cfg.interface1.ip) { if (arg_debug) printf("Configuring %d.%d.%d.%d address on interface %s\n", PRINT_IP(cfg.interface1.ip), cfg.interface1.dev); net_if_ip(cfg.interface1.dev, cfg.interface1.ip, cfg.interface1.mask, cfg.interface1.mtu); net_if_up(cfg.interface1.dev); } if (cfg.interface2.configured && cfg.interface2.ip) { if (arg_debug) printf("Configuring %d.%d.%d.%d address on interface %s\n", PRINT_IP(cfg.interface2.ip), cfg.interface2.dev); net_if_ip(cfg.interface2.dev, cfg.interface2.ip, cfg.interface2.mask, cfg.interface2.mtu); net_if_up(cfg.interface2.dev); } if (cfg.interface3.configured && cfg.interface3.ip) { if (arg_debug) printf("Configuring %d.%d.%d.%d address on interface %s\n", PRINT_IP(cfg.interface3.ip), cfg.interface3.dev); net_if_ip(cfg.interface3.dev, cfg.interface3.ip, cfg.interface3.mask, cfg.interface3.mtu); net_if_up(cfg.interface3.dev); } if (arg_debug) printf("Network namespace enabled\n"); } // if any dns server is configured, it is time to set it now fs_resolvconf(); fs_logger_print(); fs_logger_change_owner(); // print network configuration if (!arg_quiet) { if (any_bridge_configured() || any_interface_configured() || cfg.defaultgw || cfg.dns1) { printf("\n"); if (any_bridge_configured() || any_interface_configured()) net_ifprint(); if (cfg.defaultgw != 0) printf("Default gateway %d.%d.%d.%d\n", PRINT_IP(cfg.defaultgw)); if (cfg.dns1 != 0) printf("DNS server %d.%d.%d.%d\n", PRINT_IP(cfg.dns1)); if (cfg.dns2 != 0) printf("DNS server %d.%d.%d.%d\n", PRINT_IP(cfg.dns2)); if (cfg.dns3 != 0) printf("DNS server %d.%d.%d.%d\n", PRINT_IP(cfg.dns3)); printf("\n"); } } fs_delete_cp_command(); //**************************** // set application environment //**************************** prctl(PR_SET_PDEATHSIG, SIGKILL, 0, 0, 0); // kill the child in case the parent died int cwd = 0; if (cfg.cwd) { if (chdir(cfg.cwd) == 0) cwd = 1; } if (!cwd) { if (chdir("/") < 0) errExit("chdir"); if (cfg.homedir) { struct stat s; if (stat(cfg.homedir, &s) == 0) { /* coverity[toctou] */ if (chdir(cfg.homedir) < 0) errExit("chdir"); } } } // set environment env_defaults(); // set user-supplied environment variables env_apply(); // set nice if (arg_nice) { errno = 0; int rv = nice(cfg.nice); (void) rv; if (errno) { fprintf(stderr, "Warning: cannot set nice value\n"); errno = 0; } } // clean /tmp/.X11-unix sockets fs_x11(); //**************************** // set security filters //**************************** // set capabilities if (!arg_noroot) set_caps(); // set rlimits set_rlimits(); // set seccomp #ifdef HAVE_SECCOMP // install protocol filter if (cfg.protocol) { protocol_filter(); // install filter protocol_filter_save(); // save filter in PROTOCOL_CFG } // if a keep list is available, disregard the drop list if (arg_seccomp == 1) { if (cfg.seccomp_list_keep) seccomp_filter_keep(); else if (cfg.seccomp_list_errno) seccomp_filter_errno(); else seccomp_filter_drop(enforce_seccomp); } #endif // set cpu affinity if (cfg.cpus) { save_cpu(); // save cpu affinity mask to CPU_CFG file set_cpu_affinity(); } // save cgroup in CGROUP_CFG file if (cfg.cgroup) save_cgroup(); //**************************************** // drop privileges or create a new user namespace //**************************************** save_nogroups(); if (arg_noroot) { int rv = unshare(CLONE_NEWUSER); if (rv == -1) { fprintf(stderr, "Error: cannot mount a new user namespace\n"); perror("unshare"); drop_privs(arg_nogroups); } } else drop_privs(arg_nogroups); // notify parent that new user namespace has been created so a proper // UID/GID map can be setup notify_other(child_to_parent_fds[1]); close(child_to_parent_fds[1]); // wait for parent to finish setting up a proper UID/GID map wait_for_other(parent_to_child_fds[0]); close(parent_to_child_fds[0]); // somehow, the new user namespace resets capabilities; // we need to do them again if (arg_noroot) { set_caps(); if (arg_debug) printf("noroot user namespace installed\n"); } //**************************************** // fork the application and monitor it //**************************************** pid_t app_pid = fork(); if (app_pid == -1) errExit("fork"); if (app_pid == 0) { prctl(PR_SET_PDEATHSIG, SIGKILL, 0, 0, 0); // kill the child in case the parent died start_application(); // start app } monitor_application(app_pid); // monitor application return 0; }
void join(pid_t pid, int argc, char **argv, int index) { EUID_ASSERT(); char *homedir = cfg.homedir; extract_command(argc, argv, index); signal (SIGTERM, signal_handler); // if the pid is that of a firejail process, use the pid of the first child process EUID_ROOT(); char *comm = pid_proc_comm(pid); EUID_USER(); if (comm) { if (strcmp(comm, "firejail") == 0) { pid_t child; if (find_child(pid, &child) == 0) { pid = child; printf("Switching to pid %u, the first child process inside the sandbox\n", (unsigned) pid); } } free(comm); } // check privileges for non-root users uid_t uid = getuid(); if (uid != 0) { uid_t sandbox_uid = pid_get_uid(pid); if (uid != sandbox_uid) { fprintf(stderr, "Error: permission is denied to join a sandbox created by a different user.\n"); exit(1); } } EUID_ROOT(); // in user mode set caps seccomp, cpu, cgroup, etc if (getuid() != 0) { extract_caps_seccomp(pid); extract_cpu(pid); extract_cgroup(pid); extract_nogroups(pid); extract_user_namespace(pid); } // set cgroup if (cfg.cgroup) // not available for uid 0 set_cgroup(cfg.cgroup); // join namespaces if (arg_join_network) { if (join_namespace(pid, "net")) exit(1); } else if (arg_join_filesystem) { if (join_namespace(pid, "mnt")) exit(1); } else { if (join_namespace(pid, "ipc") || join_namespace(pid, "net") || join_namespace(pid, "pid") || join_namespace(pid, "uts") || join_namespace(pid, "mnt")) exit(1); } pid_t child = fork(); if (child < 0) errExit("fork"); if (child == 0) { // chroot into /proc/PID/root directory char *rootdir; if (asprintf(&rootdir, "/proc/%d/root", pid) == -1) errExit("asprintf"); int rv; if (!arg_join_network) { rv = chroot(rootdir); // this will fail for processes in sandboxes not started with --chroot option if (rv == 0) printf("changing root to %s\n", rootdir); } prctl(PR_SET_PDEATHSIG, SIGKILL, 0, 0, 0); // kill the child in case the parent died if (chdir("/") < 0) errExit("chdir"); if (homedir) { struct stat s; if (stat(homedir, &s) == 0) { /* coverity[toctou] */ if (chdir(homedir) < 0) errExit("chdir"); } } // set cpu affinity if (cfg.cpus) // not available for uid 0 set_cpu_affinity(); // set caps filter if (apply_caps == 1) // not available for uid 0 caps_set(caps); #ifdef HAVE_SECCOMP // read cfg.protocol from file if (getuid() != 0) protocol_filter_load(RUN_PROTOCOL_CFG); if (cfg.protocol) { // not available for uid 0 seccomp_load(RUN_SECCOMP_PROTOCOL); // install filter } // set seccomp filter if (apply_seccomp == 1) // not available for uid 0 seccomp_load(RUN_SECCOMP_CFG); #endif // mount user namespace or drop privileges if (arg_noroot) { // not available for uid 0 if (arg_debug) printf("Joining user namespace\n"); if (join_namespace(1, "user")) exit(1); // user namespace resets capabilities // set caps filter if (apply_caps == 1) // not available for uid 0 caps_set(caps); } else drop_privs(arg_nogroups); // nogroups not available for uid 0 // set nice if (arg_nice) { errno = 0; int rv = nice(cfg.nice); (void) rv; if (errno) { fprintf(stderr, "Warning: cannot set nice value\n"); errno = 0; } } env_defaults(); if (cfg.command_line == NULL) { assert(cfg.shell); cfg.command_line = cfg.shell; cfg.window_title = cfg.shell; } int cwd = 0; if (cfg.cwd) { if (chdir(cfg.cwd) == 0) cwd = 1; } if (!cwd) { if (chdir("/") < 0) errExit("chdir"); if (cfg.homedir) { struct stat s; if (stat(cfg.homedir, &s) == 0) { /* coverity[toctou] */ if (chdir(cfg.homedir) < 0) errExit("chdir"); } } } start_application(); // it will never get here!!! } // wait for the child to finish waitpid(child, NULL, 0); flush_stdin(); exit(0); }