cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
Log | Files | Refs | README | LICENSE | sfeed.txt

read.c (3548B)

      1/*
      2 * Copyright © 2018 Alexey Dobriyan <adobriyan@gmail.com>
      3 *
      4 * Permission to use, copy, modify, and distribute this software for any
      5 * purpose with or without fee is hereby granted, provided that the above
      6 * copyright notice and this permission notice appear in all copies.
      7 *
      8 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
      9 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
     10 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
     11 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
     12 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
     13 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
     14 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
     15 */
     16// Test
     17// 1) read and lseek on every file in /proc
     18// 2) readlink of every symlink in /proc
     19// 3) recursively (1) + (2) for every directory in /proc
     20// 4) write to /proc/*/clear_refs and /proc/*/task/*/clear_refs
     21// 5) write to /proc/sysrq-trigger
     22#undef NDEBUG
     23#include <assert.h>
     24#include <errno.h>
     25#include <sys/types.h>
     26#include <dirent.h>
     27#include <stdbool.h>
     28#include <stdlib.h>
     29#include <stdio.h>
     30#include <string.h>
     31#include <sys/stat.h>
     32#include <sys/vfs.h>
     33#include <fcntl.h>
     34#include <unistd.h>
     35
     36#include "proc.h"
     37
     38static void f_reg(DIR *d, const char *filename)
     39{
     40	char buf[4096];
     41	int fd;
     42	ssize_t rv;
     43
     44	/* read from /proc/kmsg can block */
     45	fd = openat(dirfd(d), filename, O_RDONLY|O_NONBLOCK);
     46	if (fd == -1)
     47		return;
     48	/* struct proc_ops::proc_lseek is mandatory if file is seekable. */
     49	(void)lseek(fd, 0, SEEK_SET);
     50	rv = read(fd, buf, sizeof(buf));
     51	assert((0 <= rv && rv <= sizeof(buf)) || rv == -1);
     52	close(fd);
     53}
     54
     55static void f_reg_write(DIR *d, const char *filename, const char *buf, size_t len)
     56{
     57	int fd;
     58	ssize_t rv;
     59
     60	fd = openat(dirfd(d), filename, O_WRONLY);
     61	if (fd == -1)
     62		return;
     63	rv = write(fd, buf, len);
     64	assert((0 <= rv && rv <= len) || rv == -1);
     65	close(fd);
     66}
     67
     68static void f_lnk(DIR *d, const char *filename)
     69{
     70	char buf[4096];
     71	ssize_t rv;
     72
     73	rv = readlinkat(dirfd(d), filename, buf, sizeof(buf));
     74	assert((0 <= rv && rv <= sizeof(buf)) || rv == -1);
     75}
     76
     77static void f(DIR *d, unsigned int level)
     78{
     79	struct dirent *de;
     80
     81	de = xreaddir(d);
     82	assert(de->d_type == DT_DIR);
     83	assert(streq(de->d_name, "."));
     84
     85	de = xreaddir(d);
     86	assert(de->d_type == DT_DIR);
     87	assert(streq(de->d_name, ".."));
     88
     89	while ((de = xreaddir(d))) {
     90		assert(!streq(de->d_name, "."));
     91		assert(!streq(de->d_name, ".."));
     92
     93		switch (de->d_type) {
     94			DIR *dd;
     95			int fd;
     96
     97		case DT_REG:
     98			if (level == 0 && streq(de->d_name, "sysrq-trigger")) {
     99				f_reg_write(d, de->d_name, "h", 1);
    100			} else if (level == 1 && streq(de->d_name, "clear_refs")) {
    101				f_reg_write(d, de->d_name, "1", 1);
    102			} else if (level == 3 && streq(de->d_name, "clear_refs")) {
    103				f_reg_write(d, de->d_name, "1", 1);
    104			} else {
    105				f_reg(d, de->d_name);
    106			}
    107			break;
    108		case DT_DIR:
    109			fd = openat(dirfd(d), de->d_name, O_DIRECTORY|O_RDONLY);
    110			if (fd == -1)
    111				continue;
    112			dd = fdopendir(fd);
    113			if (!dd)
    114				continue;
    115			f(dd, level + 1);
    116			closedir(dd);
    117			break;
    118		case DT_LNK:
    119			f_lnk(d, de->d_name);
    120			break;
    121		default:
    122			assert(0);
    123		}
    124	}
    125}
    126
    127int main(void)
    128{
    129	DIR *d;
    130	struct statfs sfs;
    131
    132	d = opendir("/proc");
    133	if (!d)
    134		return 4;
    135
    136	/* Ensure /proc is proc. */
    137	if (fstatfs(dirfd(d), &sfs) == -1) {
    138		return 1;
    139	}
    140	if (sfs.f_type != 0x9fa0) {
    141		fprintf(stderr, "error: unexpected f_type %lx\n", (long)sfs.f_type);
    142		return 2;
    143	}
    144
    145	f(d, 0);
    146
    147	return 0;
    148}