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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copyfile.c (2862B)

      1// SPDX-License-Identifier: GPL-2.0
      2#include "util/copyfile.h"
      3#include "util/namespaces.h"
      4#include <internal/lib.h>
      5#include <sys/mman.h>
      6#include <sys/stat.h>
      7#include <errno.h>
      8#include <fcntl.h>
      9#include <stdio.h>
     10#include <stdlib.h>
     11#include <string.h>
     12#include <unistd.h>
     13
     14static int slow_copyfile(const char *from, const char *to, struct nsinfo *nsi)
     15{
     16	int err = -1;
     17	char *line = NULL;
     18	size_t n;
     19	FILE *from_fp, *to_fp;
     20	struct nscookie nsc;
     21
     22	nsinfo__mountns_enter(nsi, &nsc);
     23	from_fp = fopen(from, "r");
     24	nsinfo__mountns_exit(&nsc);
     25	if (from_fp == NULL)
     26		goto out;
     27
     28	to_fp = fopen(to, "w");
     29	if (to_fp == NULL)
     30		goto out_fclose_from;
     31
     32	while (getline(&line, &n, from_fp) > 0)
     33		if (fputs(line, to_fp) == EOF)
     34			goto out_fclose_to;
     35	err = 0;
     36out_fclose_to:
     37	fclose(to_fp);
     38	free(line);
     39out_fclose_from:
     40	fclose(from_fp);
     41out:
     42	return err;
     43}
     44
     45int copyfile_offset(int ifd, loff_t off_in, int ofd, loff_t off_out, u64 size)
     46{
     47	void *ptr;
     48	loff_t pgoff;
     49
     50	pgoff = off_in & ~(page_size - 1);
     51	off_in -= pgoff;
     52
     53	ptr = mmap(NULL, off_in + size, PROT_READ, MAP_PRIVATE, ifd, pgoff);
     54	if (ptr == MAP_FAILED)
     55		return -1;
     56
     57	while (size) {
     58		ssize_t ret = pwrite(ofd, ptr + off_in, size, off_out);
     59		if (ret < 0 && errno == EINTR)
     60			continue;
     61		if (ret <= 0)
     62			break;
     63
     64		size -= ret;
     65		off_in += ret;
     66		off_out += ret;
     67	}
     68	munmap(ptr, off_in + size);
     69
     70	return size ? -1 : 0;
     71}
     72
     73static int copyfile_mode_ns(const char *from, const char *to, mode_t mode,
     74			    struct nsinfo *nsi)
     75{
     76	int fromfd, tofd;
     77	struct stat st;
     78	int err;
     79	char *tmp = NULL, *ptr = NULL;
     80	struct nscookie nsc;
     81
     82	nsinfo__mountns_enter(nsi, &nsc);
     83	err = stat(from, &st);
     84	nsinfo__mountns_exit(&nsc);
     85	if (err)
     86		goto out;
     87	err = -1;
     88
     89	/* extra 'x' at the end is to reserve space for '.' */
     90	if (asprintf(&tmp, "%s.XXXXXXx", to) < 0) {
     91		tmp = NULL;
     92		goto out;
     93	}
     94	ptr = strrchr(tmp, '/');
     95	if (!ptr)
     96		goto out;
     97	ptr = memmove(ptr + 1, ptr, strlen(ptr) - 1);
     98	*ptr = '.';
     99
    100	tofd = mkstemp(tmp);
    101	if (tofd < 0)
    102		goto out;
    103
    104	if (st.st_size == 0) { /* /proc? do it slowly... */
    105		err = slow_copyfile(from, tmp, nsi);
    106		if (!err && fchmod(tofd, mode))
    107			err = -1;
    108		goto out_close_to;
    109	}
    110
    111	if (fchmod(tofd, mode))
    112		goto out_close_to;
    113
    114	nsinfo__mountns_enter(nsi, &nsc);
    115	fromfd = open(from, O_RDONLY);
    116	nsinfo__mountns_exit(&nsc);
    117	if (fromfd < 0)
    118		goto out_close_to;
    119
    120	err = copyfile_offset(fromfd, 0, tofd, 0, st.st_size);
    121
    122	close(fromfd);
    123out_close_to:
    124	close(tofd);
    125	if (!err)
    126		err = link(tmp, to);
    127	unlink(tmp);
    128out:
    129	free(tmp);
    130	return err;
    131}
    132
    133int copyfile_ns(const char *from, const char *to, struct nsinfo *nsi)
    134{
    135	return copyfile_mode_ns(from, to, 0755, nsi);
    136}
    137
    138int copyfile_mode(const char *from, const char *to, mode_t mode)
    139{
    140	return copyfile_mode_ns(from, to, mode, NULL);
    141}
    142
    143int copyfile(const char *from, const char *to)
    144{
    145	return copyfile_mode(from, to, 0755);
    146}