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