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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.
*/
#include "firejail.h"
#include <sys/stat.h>
#define MAXBUF 4096
void save_cgroup(void) {
if (cfg.cgroup == NULL)
return;
FILE *fp = fopen(RUN_CGROUP_CFG, "w");
if (fp) {
fprintf(fp, "%s", cfg.cgroup);
fflush(0);
SET_PERMS_STREAM(fp, 0, 0, 0644);
if (fclose(fp))
goto errout;
}
else
goto errout;
return;
errout:
fprintf(stderr, "Error: cannot save cgroup\n");
exit(1);
}
void load_cgroup(const char *fname) {
if (!fname)
return;
FILE *fp = fopen(fname, "r");
if (fp) {
char buf[MAXBUF];
if (fgets(buf, MAXBUF, fp)) {
cfg.cgroup = strdup(buf);
if (!cfg.cgroup)
errExit("strdup");
}
else
goto errout;
fclose(fp);
return;
}
errout:
fwarning("cannot load control group\n");
if (fp)
fclose(fp);
}
void set_cgroup(const char *path) {
EUID_ASSERT();
invalid_filename(path, 0); // no globbing
// path starts with /sys/fs/cgroup
if (strncmp(path, "/sys/fs/cgroup", 14) != 0)
goto errout;
// path ends in tasks
char *ptr = strstr(path, "tasks");
if (!ptr)
goto errout;
if (*(ptr + 5) != '\0')
goto errout;
// no .. traversal
ptr = strstr(path, "..");
if (ptr)
goto errout;
// tasks file exists
struct stat s;
if (stat(path, &s) == -1)
goto errout;
// task file belongs to the user running the sandbox
if (s.st_uid != getuid() && s.st_gid != getgid())
goto errout2;
// add the task to cgroup
/* coverity[toctou] */
FILE *fp = fopen(path, "a");
if (!fp)
goto errout;
pid_t pid = getpid();
int rv = fprintf(fp, "%d\n", pid);
(void) rv;
fclose(fp);
return;
errout:
fprintf(stderr, "Error: invalid cgroup\n");
exit(1);
errout2:
fprintf(stderr, "Error: you don't have permissions to use this control group\n");
exit(1);
}
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