cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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test-fsmount.c (2686B)

      1// SPDX-License-Identifier: GPL-2.0-or-later
      2/* fd-based mount test.
      3 *
      4 * Copyright (C) 2017 Red Hat, Inc. All Rights Reserved.
      5 * Written by David Howells (dhowells@redhat.com)
      6 */
      7
      8#include <stdio.h>
      9#include <stdlib.h>
     10#include <unistd.h>
     11#include <errno.h>
     12#include <fcntl.h>
     13#include <sys/prctl.h>
     14#include <sys/wait.h>
     15#include <linux/mount.h>
     16#include <linux/unistd.h>
     17
     18#define E(x) do { if ((x) == -1) { perror(#x); exit(1); } } while(0)
     19
     20static void check_messages(int fd)
     21{
     22	char buf[4096];
     23	int err, n;
     24
     25	err = errno;
     26
     27	for (;;) {
     28		n = read(fd, buf, sizeof(buf));
     29		if (n < 0)
     30			break;
     31		n -= 2;
     32
     33		switch (buf[0]) {
     34		case 'e':
     35			fprintf(stderr, "Error: %*.*s\n", n, n, buf + 2);
     36			break;
     37		case 'w':
     38			fprintf(stderr, "Warning: %*.*s\n", n, n, buf + 2);
     39			break;
     40		case 'i':
     41			fprintf(stderr, "Info: %*.*s\n", n, n, buf + 2);
     42			break;
     43		}
     44	}
     45
     46	errno = err;
     47}
     48
     49static __attribute__((noreturn))
     50void mount_error(int fd, const char *s)
     51{
     52	check_messages(fd);
     53	fprintf(stderr, "%s: %m\n", s);
     54	exit(1);
     55}
     56
     57/* Hope -1 isn't a syscall */
     58#ifndef __NR_fsopen
     59#define __NR_fsopen -1
     60#endif
     61#ifndef __NR_fsmount
     62#define __NR_fsmount -1
     63#endif
     64#ifndef __NR_fsconfig
     65#define __NR_fsconfig -1
     66#endif
     67#ifndef __NR_move_mount
     68#define __NR_move_mount -1
     69#endif
     70
     71
     72static inline int fsopen(const char *fs_name, unsigned int flags)
     73{
     74	return syscall(__NR_fsopen, fs_name, flags);
     75}
     76
     77static inline int fsmount(int fsfd, unsigned int flags, unsigned int ms_flags)
     78{
     79	return syscall(__NR_fsmount, fsfd, flags, ms_flags);
     80}
     81
     82static inline int fsconfig(int fsfd, unsigned int cmd,
     83			   const char *key, const void *val, int aux)
     84{
     85	return syscall(__NR_fsconfig, fsfd, cmd, key, val, aux);
     86}
     87
     88static inline int move_mount(int from_dfd, const char *from_pathname,
     89			     int to_dfd, const char *to_pathname,
     90			     unsigned int flags)
     91{
     92	return syscall(__NR_move_mount,
     93		       from_dfd, from_pathname,
     94		       to_dfd, to_pathname, flags);
     95}
     96
     97#define E_fsconfig(fd, cmd, key, val, aux)				\
     98	do {								\
     99		if (fsconfig(fd, cmd, key, val, aux) == -1)		\
    100			mount_error(fd, key ?: "create");		\
    101	} while (0)
    102
    103int main(int argc, char *argv[])
    104{
    105	int fsfd, mfd;
    106
    107	/* Mount a publically available AFS filesystem */
    108	fsfd = fsopen("afs", 0);
    109	if (fsfd == -1) {
    110		perror("fsopen");
    111		exit(1);
    112	}
    113
    114	E_fsconfig(fsfd, FSCONFIG_SET_STRING, "source", "#grand.central.org:root.cell.", 0);
    115	E_fsconfig(fsfd, FSCONFIG_CMD_CREATE, NULL, NULL, 0);
    116
    117	mfd = fsmount(fsfd, 0, MOUNT_ATTR_RDONLY);
    118	if (mfd < 0)
    119		mount_error(fsfd, "fsmount");
    120	E(close(fsfd));
    121
    122	if (move_mount(mfd, "", AT_FDCWD, "/mnt", MOVE_MOUNT_F_EMPTY_PATH) < 0) {
    123		perror("move_mount");
    124		exit(1);
    125	}
    126
    127	E(close(mfd));
    128	exit(0);
    129}