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/*
* Copyright (C) 2014-2018 Firejail Authors
*
* This file is part of firejail project
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
// https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=770fe30a46a12b6fb6b63fbe1737654d28e84844
// sudo mount -o loop krita-3.0-x86_64.appimage mnt
#include "firejail.h"
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mount.h>
#include <fcntl.h>
#include <linux/loop.h>
#include <errno.h>
static char *devloop = NULL; // device file
static char *mntdir = NULL; // mount point in /tmp directory
#ifdef LOOP_CTL_GET_FREE // test for older kernels; this definition is found in /usr/include/linux/loop.h
static void err_loop(void) {
fprintf(stderr, "Error: cannot configure loopback device\n");
exit(1);
}
#endif
void appimage_set(const char *appimage) {
assert(appimage);
assert(devloop == NULL); // don't call this twice!
EUID_ASSERT();
#ifdef LOOP_CTL_GET_FREE
// check appimage file
invalid_filename(appimage, 0); // no globbing
if (access(appimage, R_OK) == -1) {
fprintf(stderr, "Error: cannot access AppImage file\n");
exit(1);
}
// get appimage type and ELF size
// a value of 0 means we are dealing with a type1 appimage
long unsigned int size = appimage2_size(appimage);
if (arg_debug)
printf("AppImage ELF size %lu\n", size);
// open appimage file
/* coverity[toctou] */
int ffd = open(appimage, O_RDONLY|O_CLOEXEC);
if (ffd == -1) {
fprintf(stderr, "Error: cannot open AppImage file\n");
exit(1);
}
// find or allocate a free loop device to use
EUID_ROOT();
int cfd = open("/dev/loop-control", O_RDWR);
if (cfd == -1)
err_loop();
int devnr = ioctl(cfd, LOOP_CTL_GET_FREE);
if (devnr == -1)
err_loop();
close(cfd);
if (asprintf(&devloop, "/dev/loop%d", devnr) == -1)
errExit("asprintf");
int lfd = open(devloop, O_RDONLY);
if (lfd == -1)
err_loop();
if (ioctl(lfd, LOOP_SET_FD, ffd) == -1)
err_loop();
if (size) {
struct loop_info64 info;
memset(&info, 0, sizeof(struct loop_info64));
info.lo_offset = size;
if (ioctl(lfd, LOOP_SET_STATUS64, &info) == -1)
err_loop();
}
close(lfd);
close(ffd);
EUID_USER();
// creates appimage mount point perms 0700
if (asprintf(&mntdir, "%s/.appimage-%u", RUN_FIREJAIL_APPIMAGE_DIR, getpid()) == -1)
errExit("asprintf");
EUID_ROOT();
mkdir_attr(mntdir, 0700, getuid(), getgid());
EUID_USER();
// mount
char *mode;
if (asprintf(&mode, "mode=700,uid=%d,gid=%d", getuid(), getgid()) == -1)
errExit("asprintf");
unsigned long flags = MS_MGC_VAL|MS_RDONLY;
if (getuid())
flags |= MS_NODEV|MS_NOSUID;
EUID_ROOT();
if (size == 0) {
fmessage("Mounting appimage type 1\n");
if (mount(devloop, mntdir, "iso9660", flags, mode) < 0)
errExit("mounting appimage");
}
else {
fmessage("Mounting appimage type 2\n");
if (mount(devloop, mntdir, "squashfs", flags, mode) < 0)
errExit("mounting appimage");
}
if (arg_debug)
printf("appimage mounted on %s\n", mntdir);
EUID_USER();
// set environment
if (setenv("APPIMAGE", appimage, 1) < 0)
errExit("setenv");
if (mntdir && setenv("APPDIR", mntdir, 1) < 0)
errExit("setenv");
// build new command line
if (asprintf(&cfg.command_line, "%s/AppRun", mntdir) == -1)
errExit("asprintf");
free(mode);
#ifdef HAVE_GCOV
__gcov_flush();
#endif
#else
fprintf(stderr, "Error: /dev/loop-control interface is not supported by your kernel\n");
exit(1);
#endif
}
void appimage_clear(void) {
int rv;
EUID_ROOT();
if (mntdir) {
int i;
int rv = 0;
for (i = 0; i < 5; i++) {
rv = umount2(mntdir, MNT_FORCE);
if (rv == 0) {
fmessage("AppImage unmounted\n");
break;
}
if (rv == -1 && errno == EBUSY) {
fwarning("EBUSY error trying to unmount %s\n", mntdir);
sleep(2);
continue;
}
// rv = -1
if (!arg_quiet) {
fwarning("error trying to unmount %s\n", mntdir);
perror("umount");
}
}
if (rv == 0) {
rmdir(mntdir);
free(mntdir);
}
}
if (devloop) {
int lfd = open(devloop, O_RDONLY);
if (lfd != -1) {
rv = ioctl(lfd, LOOP_CLR_FD, 0);
(void) rv;
close(lfd);
}
}
}
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