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/*
* SPDX-License-Identifier: ISC
*
* Copyright (c) 2012, 2014-2022 Todd C. Miller <Todd.Miller@sudo.ws>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
/*
* This is an open source non-commercial project. Dear PVS-Studio, please check it.
* PVS-Studio Static Code Analyzer for C, C++ and C#: http://www.viva64.com
*/
#include <config.h>
#include <sys/stat.h>
#include <errno.h>
#include <fcntl.h>
#include <string.h>
#include <unistd.h>
#include <sudo_compat.h>
#include <sudo_util.h>
#include <sudo_debug.h>
/*
* Verify that path is the right type and not writable by other users.
*/
static int
sudo_check_secure(struct stat *sb, unsigned int type, uid_t uid, gid_t gid)
{
int ret = SUDO_PATH_SECURE;
debug_decl(sudo_check_secure, SUDO_DEBUG_UTIL);
if ((sb->st_mode & S_IFMT) != type) {
ret = SUDO_PATH_BAD_TYPE;
} else if (uid != (uid_t)-1 && sb->st_uid != uid) {
ret = SUDO_PATH_WRONG_OWNER;
} else if (sb->st_mode & S_IWOTH) {
ret = SUDO_PATH_WORLD_WRITABLE;
} else if (ISSET(sb->st_mode, S_IWGRP) &&
(gid == (gid_t)-1 || sb->st_gid != gid)) {
ret = SUDO_PATH_GROUP_WRITABLE;
}
debug_return_int(ret);
}
/*
* Verify that path is the right type and not writable by other users.
*/
static int
sudo_secure_path(const char *path, unsigned int type, uid_t uid, gid_t gid,
struct stat *sb)
{
int ret = SUDO_PATH_MISSING;
struct stat stat_buf;
debug_decl(sudo_secure_path, SUDO_DEBUG_UTIL);
if (sb == NULL)
sb = &stat_buf;
if (path != NULL && stat(path, sb) == 0)
ret = sudo_check_secure(sb, type, uid, gid);
debug_return_int(ret);
}
/*
* Verify that path is a regular file and not writable by other users.
* Not currently used.
*/
int
sudo_secure_file_v1(const char *path, uid_t uid, gid_t gid, struct stat *sb)
{
return sudo_secure_path(path, S_IFREG, uid, gid, sb);
}
/*
* Verify that path is a directory and not writable by other users.
*/
int
sudo_secure_dir_v1(const char *path, uid_t uid, gid_t gid, struct stat *sb)
{
return sudo_secure_path(path, S_IFDIR, uid, gid, sb);
}
/*
* Verify that fd matches type and not writable by other users.
*/
int
sudo_secure_fd_v1(int fd, unsigned int type, uid_t uid, gid_t gid,
struct stat *sb)
{
int ret = SUDO_PATH_MISSING;
debug_decl(sudo_secure_fd, SUDO_DEBUG_UTIL);
if (fd != -1 && fstat(fd, sb) == 0)
ret = sudo_check_secure(sb, type, uid, gid);
debug_return_int(ret);
}
/*
* Open path read-only as long as it is not writable by other users.
* Returns an open file descriptor on success, else -1.
* Sets error to SUDO_PATH_SECURE on success, and a value < 0 on failure.
*/
static int
sudo_secure_open(const char *path, unsigned int type, uid_t uid, gid_t gid,
struct stat *sb, int *error)
{
struct stat stat_buf;
int fd;
debug_decl(sudo_secure_open, SUDO_DEBUG_UTIL);
if (sb == NULL)
sb = &stat_buf;
fd = open(path, O_RDONLY|O_NONBLOCK);
if (fd == -1 || fstat(fd, sb) != 0) {
if (fd != -1)
close(fd);
*error = SUDO_PATH_MISSING;
debug_return_int(-1);
}
*error = sudo_check_secure(sb, type, uid, gid);
if (*error == SUDO_PATH_SECURE) {
(void)fcntl(fd, F_SETFL, fcntl(fd, F_GETFL, 0) & ~O_NONBLOCK);
} else {
/* Not secure, caller can check error flag. */
close(fd);
fd = -1;
}
debug_return_int(fd);
}
int
sudo_secure_open_file_v1(const char *path, uid_t uid, gid_t gid,
struct stat *sb, int *error)
{
return sudo_secure_open(path, S_IFREG, uid, gid, sb, error);
}
int
sudo_secure_open_dir_v1(const char *path, uid_t uid, gid_t gid,
struct stat *sb, int *error)
{
return sudo_secure_open(path, S_IFDIR, uid, gid, sb, error);
}
/*
* Open the first file found in a colon-separated list of paths.
* Subsequent files in the path are only attempted if the
* previous file does not exist. Errors other than ENOENT are
* considered fatal and will stop processing the path.
* Sets name based on the last file it tried to open, even on error.
*/
int
sudo_open_conf_path_v1(const char *path, char *name, size_t namesize,
int (*fn)(const char *, int))
{
const char *cp, *ep, *path_end;
int fd = -1;
debug_decl(sudo_open_conf_path, SUDO_DEBUG_UTIL);
path_end = path + strlen(path);
for (cp = sudo_strsplit(path, path_end, ":", &ep);
cp != NULL; cp = sudo_strsplit(NULL, path_end, ":", &ep)) {
const size_t len = (size_t)(ep - cp);
if (len >= namesize) {
/* We always set name, even on error. */
memcpy(name, cp, namesize - 1);
name[namesize - 1] = '\0';
errno = ENAMETOOLONG;
break;
}
memcpy(name, cp, len);
name[len] = '\0';
fd = fn ?
fn(name, O_RDONLY|O_NONBLOCK) : open(name, O_RDONLY|O_NONBLOCK);
if (fd != -1) {
(void)fcntl(fd, F_SETFL, fcntl(fd, F_GETFL, 0) & ~O_NONBLOCK);
break;
}
if (errno != ENOENT)
break;
}
debug_return_int(fd);
}
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