From 25b58f2d549c0fb67e33849c2fc14106f667f404 Mon Sep 17 00:00:00 2001 From: Etienne CHAMPETIER Date: Wed, 26 Aug 2015 23:26:47 +0000 Subject: [PATCH] jail: allow to not use namespaces building a generic jail can be hard, choosing to drop some capabilities can be easier. This commit permit to use namespaces, capabilities and seccomp combined as you like. Signed-off-by: Etienne CHAMPETIER --- jail/jail.c | 76 +++++++++++++++++++++++++++++++++++++++-------------- 1 file changed, 56 insertions(+), 20 deletions(-) diff --git a/jail/jail.c b/jail/jail.c index 40b7558..f459a5e 100644 --- a/jail/jail.c +++ b/jail/jail.c @@ -42,6 +42,7 @@ static struct { char **jail_argv; char *seccomp; char *capabilities; + int namespace; int procfs; int ronly; int sysfs; @@ -233,13 +234,14 @@ static char** build_envp(const char *seccomp) static void usage(void) { fprintf(stderr, "ujail -- \n"); - fprintf(stderr, " -P \tpath where the jail will be staged\n"); - fprintf(stderr, " -S \tseccomp filter\n"); + fprintf(stderr, " -d \tshow debug log (increase num to increase verbosity)\n"); + fprintf(stderr, " -S \tseccomp filter config\n"); fprintf(stderr, " -C \tcapabilities drop config\n"); fprintf(stderr, " -n \tthe name of the jail\n"); + fprintf(stderr, "namespace jail options:\n"); + fprintf(stderr, " -P \tpath where the jail will be staged\n"); fprintf(stderr, " -r \treadonly files that should be staged\n"); fprintf(stderr, " -w \twriteable files that should be staged\n"); - fprintf(stderr, " -d \tshow debug log (increase num to increase verbosity)\n"); fprintf(stderr, " -p\t\tjail has /proc\n"); fprintf(stderr, " -s\t\tjail has /sys\n"); fprintf(stderr, " -l\t\tjail has /dev/log\n"); @@ -248,20 +250,14 @@ static void usage(void) fprintf(stderr, "\nWarning: by default root inside the jail is the same\n\ and he has the same powers as root outside the jail,\n\ thus he can escape the jail and/or break stuff.\n\ -Please use an appropriate seccomp/capabilities filter (-S/-C) to restrict his powers\n"); +Please use seccomp/capabilities (-S/-C) to restrict his powers\n\n\ +If you use none of the namespace jail options,\n\ +ujail will not use namespace/build a jail,\n\ +and will only drop capabilities/apply seccomp filter.\n\n"); } -static int spawn_jail(void *arg) +static int exec_jail() { - if (opts.name && sethostname(opts.name, strlen(opts.name))) { - ERROR("failed to sethostname: %s\n", strerror(errno)); - } - - if (build_jail_fs()) { - ERROR("failed to build jail fs"); - exit(EXIT_FAILURE); - } - char **envp = build_envp(opts.seccomp); if (!envp) exit(EXIT_FAILURE); @@ -276,6 +272,20 @@ static int spawn_jail(void *arg) exit(EXIT_FAILURE); } +static int spawn_jail(void *arg) +{ + if (opts.name && sethostname(opts.name, strlen(opts.name))) { + ERROR("failed to sethostname: %s\n", strerror(errno)); + } + + if (build_jail_fs()) { + ERROR("failed to build jail fs"); + exit(EXIT_FAILURE); + } + + return exec_jail(); +} + static int jail_running = 1; static int jail_return_code = 0; @@ -335,12 +345,15 @@ int main(int argc, char **argv) debug = atoi(optarg); break; case 'p': + opts.namespace = 1; opts.procfs = 1; break; case 'o': + opts.namespace = 1; opts.ronly = 1; break; case 's': + opts.namespace = 1; opts.sysfs = 1; break; case 'S': @@ -352,21 +365,26 @@ int main(int argc, char **argv) add_extra(optarg, 1); break; case 'P': + opts.namespace = 1; opts.path = optarg; break; case 'n': opts.name = optarg; break; case 'r': + opts.namespace = 1; add_extra(optarg, 1); break; case 'w': + opts.namespace = 1; add_extra(optarg, 0); break; case 'u': + opts.namespace = 1; add_extra(ubus, 0); break; case 'l': + opts.namespace = 1; add_extra(log, 0); break; } @@ -377,41 +395,59 @@ int main(int argc, char **argv) usage(); return EXIT_FAILURE; } + if (!(opts.namespace||opts.capabilities||opts.seccomp)) { + ERROR("Not using namespaces, capabilities or seccomp !!!\n\n"); + usage(); + return EXIT_FAILURE; + } + DEBUG("Using namespaces(%d), capabilities(%d), seccomp(%d)\n", + opts.namespace, + opts.capabilities != 0, + opts.seccomp != 0); opts.jail_argv = &argv[optind]; if (opts.name) prctl(PR_SET_NAME, opts.name, NULL, NULL, NULL); - if (!opts.path && asprintf(&opts.path, "/tmp/%s", basename(*opts.jail_argv)) == -1) { + if (opts.namespace && !opts.path && asprintf(&opts.path, "/tmp/%s", basename(*opts.jail_argv)) == -1) { ERROR("failed to asprintf root path: %s\n", strerror(errno)); return EXIT_FAILURE; } - if (mkdir(opts.path, 0755)) { + if (opts.namespace && mkdir(opts.path, 0755)) { ERROR("unable to create root path: %s (%s)\n", opts.path, strerror(errno)); return EXIT_FAILURE; } uloop_init(); - jail_process.pid = clone(spawn_jail, + if (opts.namespace) { + jail_process.pid = clone(spawn_jail, child_stack + STACK_SIZE, CLONE_NEWUTS | CLONE_NEWPID | CLONE_NEWNS | CLONE_NEWIPC | SIGCHLD, argv); + } else { + jail_process.pid = fork(); + } - if (jail_process.pid != -1) { + if (jail_process.pid > 0) { + //parent process uloop_process_add(&jail_process); uloop_run(); uloop_done(); if (jail_running) { + DEBUG("uloop interrupted, killing jail process\n"); kill(jail_process.pid, SIGTERM); waitpid(jail_process.pid, NULL, 0); } + } else if (jail_process.pid == 0) { + //fork child process + return exec_jail(); } else { - ERROR("failed to spawn namespace: %s\n", strerror(errno)); + ERROR("failed to clone/fork: %s\n", strerror(errno)); ret = EXIT_FAILURE; } - if (rmdir(opts.path)) { + if (opts.namespace && rmdir(opts.path)) { ERROR("Unable to remove root path: %s (%s)\n", opts.path, strerror(errno)); ret = EXIT_FAILURE; } -- 2.25.1