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/*
* Copyright (C) 2014-2021 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>
#ifdef HAVE_GCOV
#include <gcov.h>
#endif
static char *devloop = NULL; // device file
static long unsigned size = 0; // offset into appimage file
#define MAXBUF 4096
#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
// return 1 if found
int appimage_find_profile(const char *archive) {
assert(archive);
assert(strlen(archive));
// try to match the name of the archive with the list of programs in /usr/lib/firejail/firecfg.config
FILE *fp = fopen(LIBDIR "/firejail/firecfg.config", "r");
if (!fp) {
fprintf(stderr, "Error: cannot find %s, firejail is not correctly installed\n", LIBDIR "/firejail/firecfg.config");
exit(1);
}
char buf[MAXBUF];
while (fgets(buf, MAXBUF, fp)) {
if (*buf == '#')
continue;
char *ptr = strchr(buf, '\n');
if (ptr)
*ptr = '\0';
if (strcasestr(archive, buf)) {
fclose(fp);
return profile_find_firejail(buf, 1);
}
}
fclose(fp);
return 0;
}
void appimage_set(const char *appimage) {
assert(appimage);
assert(devloop == NULL); // don't call this twice!
EUID_ASSERT();
#ifdef LOOP_CTL_GET_FREE
// open appimage file
invalid_filename(appimage, 0); // no globbing
int ffd = open(appimage, O_RDONLY|O_CLOEXEC);
if (ffd == -1) {
fprintf(stderr, "Error: cannot read AppImage file\n");
exit(1);
}
struct stat s;
if (fstat(ffd, &s) == -1)
errExit("fstat");
if (!S_ISREG(s.st_mode)) {
fprintf(stderr, "Error: invalid AppImage file\n");
exit(1);
}
// get appimage type and ELF size
// a value of 0 means we are dealing with a type1 appimage
size = appimage2_size(ffd);
if (arg_debug)
printf("AppImage ELF size %lu\n", size);
// find or allocate a free loop device to use
EUID_ROOT();
int cfd = open("/dev/loop-control", O_RDWR|O_CLOEXEC);
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");
// associate loop device with appimage
int lfd = open(devloop, O_RDONLY|O_CLOEXEC);
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();
// set environment
char* abspath = realpath(appimage, NULL);
if (abspath == NULL)
errExit("Failed to obtain absolute path");
env_store_name_val("APPIMAGE", abspath, SETENV);
free(abspath);
env_store_name_val("APPDIR", RUN_FIREJAIL_APPIMAGE_DIR, SETENV);
if (size != 0)
env_store_name_val("ARGV0", appimage, SETENV);
if (cfg.cwd)
env_store_name_val("OWD", cfg.cwd, SETENV);
#ifdef HAVE_GCOV
__gcov_flush();
#endif
#else
fprintf(stderr, "Error: /dev/loop-control interface is not supported by your kernel\n");
exit(1);
#endif
}
// mount appimage into sandbox file system
void appimage_mount(void) {
if (!devloop)
return;
unsigned long flags = MS_MGC_VAL|MS_RDONLY;
if (getuid())
flags |= MS_NODEV|MS_NOSUID;
if (size == 0) {
fmessage("Mounting appimage type 1\n");
char *mode;
if (asprintf(&mode, "mode=700,uid=%d,gid=%d", getuid(), getgid()) == -1)
errExit("asprintf");
if (mount(devloop, RUN_FIREJAIL_APPIMAGE_DIR, "iso9660", flags, mode) < 0)
errExit("mounting appimage");
free(mode);
}
else {
fmessage("Mounting appimage type 2\n");
if (mount(devloop, RUN_FIREJAIL_APPIMAGE_DIR, "squashfs", flags, NULL) < 0)
errExit("mounting appimage");
}
}
void appimage_clear(void) {
EUID_ROOT();
if (devloop) {
int lfd = open(devloop, O_RDONLY|O_CLOEXEC);
if (lfd != -1) {
if (ioctl(lfd, LOOP_CLR_FD, 0) != -1)
fmessage("AppImage detached\n");
close(lfd);
}
}
}
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