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/*
SSSD
Check file permissions and open file
Authors:
Sumit Bose <sbose@redhat.com>
Copyright (C) 2009 Red Hat
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 3 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, see <http://www.gnu.org/licenses/>.
*/
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include "util/util.h"
errno_t check_and_open_readonly(const char *filename, int *fd, const uid_t uid,
const gid_t gid, const mode_t mode)
{
int ret;
struct stat stat_buf;
struct stat fd_stat_buf;
*fd = -1;
ret = lstat(filename, &stat_buf);
if (ret == -1) {
DEBUG(1, ("lstat for [%s] failed: [%d][%s].\n", filename, errno,
strerror(errno)));
return errno;
}
if (!S_ISREG(stat_buf.st_mode)) {
DEBUG(1, ("File [%s] is not a regular file.\n", filename));
return EINVAL;
}
if ((stat_buf.st_mode & ~S_IFMT) != mode) {
DEBUG(1, ("File [%s] has the wrong mode [%.7o], expected [%.7o].\n",
filename, (stat_buf.st_mode & ~S_IFMT), mode));
return EINVAL;
}
if (stat_buf.st_uid != uid || stat_buf.st_gid != gid) {
DEBUG(1, ("File [%s] must be owned by uid [%d] and gid [%d].\n",
filename, uid, gid));
return EINVAL;
}
*fd = open(filename, O_RDONLY);
if (*fd == -1) {
DEBUG(1, ("open [%s] failed: [%d][%s].\n", filename, errno,
strerror(errno)));
return errno;
}
ret = fstat(*fd, &fd_stat_buf);
if (ret == -1) {
DEBUG(1, ("fstat for [%s] failed: [%d][%s].\n", filename, errno,
strerror(errno)));
return errno;
}
if (stat_buf.st_dev != fd_stat_buf.st_dev ||
stat_buf.st_ino != fd_stat_buf.st_ino) {
DEBUG(1, ("File [%s] was modified between lstat and open.\n", filename));
close(*fd);
*fd = -1;
return EIO;
}
return EOK;
}
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