diff options
Diffstat (limited to 'voidnsundo.c')
| -rw-r--r-- | voidnsundo.c | 154 |
1 files changed, 154 insertions, 0 deletions
diff --git a/voidnsundo.c b/voidnsundo.c new file mode 100644 index 0000000..fac27aa --- /dev/null +++ b/voidnsundo.c @@ -0,0 +1,154 @@ +#define _GNU_SOURCE + +#include <string.h> +#include <stdio.h> +#include <stdlib.h> +#include <libgen.h> +#include <stdbool.h> +#include <getopt.h> +#include <dirent.h> +#include <errno.h> +#include <unistd.h> +#include <sched.h> +#include <sys/socket.h> +#include <sys/un.h> +#include <linux/limits.h> + +#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" + " -s: Socket directory path. When this option is not present,\n" + " " SOCK_DIR_VAR " environment variable is used. If both are\n" + " missing, defaults to " SOCK_DIR_DEFAULT ".\n" + " -V: 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; + char *sock_dir = NULL; + 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 's': + sock_dir = optarg; + break; + 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); */ + } + + /* Check socket directory. */ + DIR *dirptr = NULL; + if (!sock_dir) + sock_dir = getenv(SOCK_DIR_VAR); + if (!sock_dir) + sock_dir = SOCK_DIR_DEFAULT; + if (strlen(sock_dir) > SOCK_DIR_PATH_MAX) + ERROR_EXIT("error: socket directory path is too long.\n"); + if (!isdir(sock_dir)) + ERROR_EXIT("error: %s is not a directory.\n", sock_dir); + if (access(sock_dir, F_OK) == -1) { + ERROR_EXIT("error: failed to access socket directory: %s.\n", + strerror(errno)); + } else { + if ((dirptr = opendir(sock_dir)) == NULL) + ERROR_EXIT("error: %s is not a directory.\n", sock_dir); + } + DEBUG("sock_dir=%s\n", sock_dir); + + /* 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; + strcpy(sock_addr.sun_path, sock_dir); + strcat(sock_addr.sun_path, SOCK_NAME); + + 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 (dirptr != NULL) + closedir(dirptr); + + if (sock_fd != -1) + close(sock_fd); + + return exit_code; +}
\ No newline at end of file |