#define _GNU_SOURCE #include #include #include #include #include #include #include #include #include #include #include #include #include "config.h" #include "utils.h" #include "macros.h" bool g_verbose = false; void usage(const char *progname) { printf("Usage: %s [OPTIONS] PROGRAM [ARGS]\n", progname); printf("\n" "Options:\n" " -V: Enable verbose output.\n" " -h: Print this help.\n" " -v: Print version.\n"); } int main(int argc, char **argv) { bool binded = strcmp(basename(argv[0]), VOIDNSUNDO_NAME) != 0; int c; int sock_fd = -1; int exit_code = 1; char realpath_buf[PATH_MAX]; char cwd[PATH_MAX]; if (!binded) { if (argc < 2) { usage(argv[0]); return 0; } while ((c = getopt(argc, argv, "vhs:V")) != -1) { switch (c) { case 'v': printf("%s\n", PROG_VERSION); return 0; case 'h': usage(argv[0]); return 0; case 'V': g_verbose = true; break; case '?': return 1; } } if (!argv[optind]) { usage(argv[0]); return 1; } } else { int bytes = readlink("/proc/self/exe", realpath_buf, PATH_MAX); realpath_buf[bytes] = '\0'; /* DEBUG("/proc/self/exe points to %s\n", realpath_buf); */ } /* Get current working directory. */ getcwd(cwd, PATH_MAX); DEBUG("cwd=%s\n", cwd); /* Get namespace's fd. */ sock_fd = socket(AF_UNIX, SOCK_STREAM, 0); if (sock_fd == -1) ERROR_EXIT("socket: %s.\n", strerror(errno)); struct sockaddr_un sock_addr = {0}; sock_addr.sun_family = AF_UNIX; strncpy(sock_addr.sun_path, SOCK_PATH, 108); if (connect(sock_fd, (struct sockaddr *)&sock_addr, sizeof(sock_addr)) == -1) ERROR_EXIT("connect: %s\n", strerror(errno)); int nsfd = recv_fd(sock_fd); if (!nsfd) ERROR_EXIT("error: failed to get nsfd.\n"); if (setns(nsfd, CLONE_NEWNS) == -1) ERROR_EXIT("setns: %s.\n", strerror(errno)); /* Drop root. */ uid_t uid = getuid(); gid_t gid = getgid(); if (setreuid(uid, uid) == -1) ERROR_EXIT("setreuid: %s\n", strerror(errno)); if (setregid(gid, gid) == -1) ERROR_EXIT("setregid: %s\n", strerror(errno)); /* Restore working directory. */ if (chdir(cwd) == -1) DEBUG("chdir: %s\n", strerror(errno)); /* Launch program. */ int argind = binded ? 0 : optind; if (binded) argv[0] = realpath_buf; if (execvp(argv[argind], (char *const *)argv+argind) == -1) ERROR_EXIT("execvp(%s): %s\n", argv[argind], strerror(errno)); exit_code = 0; end: if (sock_fd != -1) close(sock_fd); return exit_code; }