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/* Copyright (C) 2022 Open Information Security Foundation
*
* You can copy, redistribute or modify this Program under the terms of
* the GNU General Public License version 2 as published by the Free
* Software Foundation.
*
* 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
* version 2 along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA.
*/
/**
* \file
*
* \author Eric Leblond <el@stamus-networks.com>
*/
#include "suricata.h"
#include "feature.h"
#include "util-conf.h"
#include "util-file.h"
#include "util-landlock.h"
#include "util-mem.h"
#include "util-path.h"
#ifndef HAVE_LINUX_LANDLOCK_H
void LandlockSandboxing(SCInstance *suri)
{
return;
}
#else /* HAVE_LINUX_LANDLOCK_H */
#include <linux/landlock.h>
#ifndef landlock_create_ruleset
static inline int landlock_create_ruleset(
const struct landlock_ruleset_attr *const attr, const size_t size, const __u32 flags)
{
return syscall(__NR_landlock_create_ruleset, attr, size, flags);
}
#endif
#ifndef landlock_add_rule
static inline int landlock_add_rule(const int ruleset_fd, const enum landlock_rule_type rule_type,
const void *const rule_attr, const __u32 flags)
{
return syscall(__NR_landlock_add_rule, ruleset_fd, rule_type, rule_attr, flags);
}
#endif
#ifndef landlock_restrict_self
static inline int landlock_restrict_self(const int ruleset_fd, const __u32 flags)
{
return syscall(__NR_landlock_restrict_self, ruleset_fd, flags);
}
#endif
#ifndef LANDLOCK_ACCESS_FS_REFER
#define LANDLOCK_ACCESS_FS_REFER (1ULL << 13)
#endif
#define _LANDLOCK_ACCESS_FS_WRITE \
(LANDLOCK_ACCESS_FS_WRITE_FILE | LANDLOCK_ACCESS_FS_REMOVE_DIR | \
LANDLOCK_ACCESS_FS_REMOVE_FILE | LANDLOCK_ACCESS_FS_MAKE_CHAR | \
LANDLOCK_ACCESS_FS_MAKE_DIR | LANDLOCK_ACCESS_FS_MAKE_REG | \
LANDLOCK_ACCESS_FS_MAKE_SOCK | LANDLOCK_ACCESS_FS_MAKE_FIFO | \
LANDLOCK_ACCESS_FS_MAKE_BLOCK | LANDLOCK_ACCESS_FS_MAKE_SYM | \
LANDLOCK_ACCESS_FS_REFER)
#define _LANDLOCK_ACCESS_FS_READ (LANDLOCK_ACCESS_FS_READ_FILE | LANDLOCK_ACCESS_FS_READ_DIR)
#define _LANDLOCK_SURI_ACCESS_FS_WRITE \
(LANDLOCK_ACCESS_FS_WRITE_FILE | LANDLOCK_ACCESS_FS_MAKE_DIR | LANDLOCK_ACCESS_FS_MAKE_REG | \
LANDLOCK_ACCESS_FS_REMOVE_FILE | LANDLOCK_ACCESS_FS_MAKE_SOCK)
struct landlock_ruleset {
int fd;
struct landlock_ruleset_attr attr;
};
static inline struct landlock_ruleset *LandlockCreateRuleset(void)
{
struct landlock_ruleset *ruleset = SCCalloc(1, sizeof(struct landlock_ruleset));
if (ruleset == NULL) {
SCLogError("Can't alloc landlock ruleset");
return NULL;
}
ruleset->attr.handled_access_fs =
_LANDLOCK_ACCESS_FS_READ | _LANDLOCK_ACCESS_FS_WRITE | LANDLOCK_ACCESS_FS_EXECUTE;
int abi = landlock_create_ruleset(NULL, 0, LANDLOCK_CREATE_RULESET_VERSION);
if (abi < 0) {
SCFree(ruleset);
return NULL;
}
if (abi < 2) {
if (RequiresFeature(FEATURE_OUTPUT_FILESTORE)) {
SCLogError("Landlock disabled: need Linux 5.19+ for file store support");
SCFree(ruleset);
return NULL;
} else {
ruleset->attr.handled_access_fs &= ~LANDLOCK_ACCESS_FS_REFER;
}
}
ruleset->fd = landlock_create_ruleset(&ruleset->attr, sizeof(ruleset->attr), 0);
if (ruleset->fd < 0) {
SCFree(ruleset);
SCLogError("Can't create landlock ruleset");
return NULL;
}
return ruleset;
}
static inline void LandlockEnforceRuleset(struct landlock_ruleset *ruleset)
{
if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0) == -1) {
SCLogError("Can't self restrict (prctl phase): %s", strerror(errno));
return;
}
if (landlock_restrict_self(ruleset->fd, 0)) {
SCLogError("Can't self restrict (landlock phase): %s", strerror(errno));
}
}
static int LandlockSandboxingAddRule(
struct landlock_ruleset *ruleset, const char *directory, uint64_t permission)
{
struct landlock_path_beneath_attr path_beneath = {
.allowed_access = permission & ruleset->attr.handled_access_fs,
};
int dir_fd = open(directory, O_PATH | O_CLOEXEC | O_DIRECTORY);
if (dir_fd == -1) {
SCLogError("Can't open %s", directory);
return -1;
}
path_beneath.parent_fd = dir_fd;
if (landlock_add_rule(ruleset->fd, LANDLOCK_RULE_PATH_BENEATH, &path_beneath, 0)) {
SCLogError("Can't add write rule: %s", strerror(errno));
close(dir_fd);
return -1;
}
close(dir_fd);
return 0;
}
static inline void LandlockSandboxingWritePath(
struct landlock_ruleset *ruleset, const char *directory)
{
if (LandlockSandboxingAddRule(ruleset, directory, _LANDLOCK_SURI_ACCESS_FS_WRITE) == 0) {
SCLogConfig("Added write permission to '%s'", directory);
}
}
static inline void LandlockSandboxingReadPath(
struct landlock_ruleset *ruleset, const char *directory)
{
if (LandlockSandboxingAddRule(ruleset, directory, _LANDLOCK_ACCESS_FS_READ) == 0) {
SCLogConfig("Added read permission to '%s'", directory);
}
}
void LandlockSandboxing(SCInstance *suri)
{
/* Read configuration variable and exit if no enforcement */
int conf_status;
if (ConfGetBool("security.landlock.enabled", &conf_status) == 0) {
conf_status = 0;
}
if (!conf_status) {
SCLogConfig("Landlock is not enabled in configuration");
return;
}
struct landlock_ruleset *ruleset = LandlockCreateRuleset();
if (ruleset == NULL) {
SCLogError("Kernel does not support Landlock");
return;
}
LandlockSandboxingWritePath(ruleset, ConfigGetLogDirectory());
struct stat sb;
if (stat(ConfigGetDataDirectory(), &sb) == 0) {
LandlockSandboxingAddRule(ruleset, ConfigGetDataDirectory(),
_LANDLOCK_SURI_ACCESS_FS_WRITE | _LANDLOCK_ACCESS_FS_READ);
}
if (suri->run_mode == RUNMODE_PCAP_FILE) {
const char *pcap_file;
if (ConfGet("pcap-file.file", &pcap_file) == 1) {
char *file_name = SCStrdup(pcap_file);
if (file_name != NULL) {
struct stat statbuf;
if (stat(file_name, &statbuf) != -1) {
if (S_ISDIR(statbuf.st_mode)) {
LandlockSandboxingReadPath(ruleset, file_name);
} else {
LandlockSandboxingReadPath(ruleset, dirname(file_name));
}
} else {
SCLogError("Can't open pcap file");
}
SCFree(file_name);
}
}
}
if (suri->sig_file) {
char *file_name = SCStrdup(suri->sig_file);
if (file_name != NULL) {
LandlockSandboxingReadPath(ruleset, dirname(file_name));
SCFree(file_name);
}
}
if (suri->pid_filename) {
char *file_name = SCStrdup(suri->pid_filename);
if (file_name != NULL) {
LandlockSandboxingWritePath(ruleset, dirname(file_name));
SCFree(file_name);
}
}
if (ConfUnixSocketIsEnable()) {
const char *socketname;
if (ConfGet("unix-command.filename", &socketname) == 1) {
if (PathIsAbsolute(socketname)) {
char *file_name = SCStrdup(socketname);
if (file_name != NULL) {
LandlockSandboxingWritePath(ruleset, dirname(file_name));
SCFree(file_name);
}
} else {
LandlockSandboxingWritePath(ruleset, LOCAL_STATE_DIR "/run/suricata/");
}
} else {
LandlockSandboxingWritePath(ruleset, LOCAL_STATE_DIR "/run/suricata/");
}
}
if (suri->sig_file_exclusive == FALSE) {
const char *rule_path;
if (ConfGet("default-rule-path", &rule_path) == 1 && rule_path) {
LandlockSandboxingReadPath(ruleset, rule_path);
}
}
ConfNode *read_dirs = ConfGetNode("security.landlock.directories.read");
if (read_dirs) {
if (!ConfNodeIsSequence(read_dirs)) {
SCLogWarning("Invalid security.landlock.directories.read configuration section: "
"expected a list of directory names.");
} else {
ConfNode *directory;
TAILQ_FOREACH (directory, &read_dirs->head, next) {
LandlockSandboxingReadPath(ruleset, directory->val);
}
}
}
ConfNode *write_dirs = ConfGetNode("security.landlock.directories.write");
if (write_dirs) {
if (!ConfNodeIsSequence(write_dirs)) {
SCLogWarning("Invalid security.landlock.directories.write configuration section: "
"expected a list of directory names.");
} else {
ConfNode *directory;
TAILQ_FOREACH (directory, &write_dirs->head, next) {
LandlockSandboxingWritePath(ruleset, directory->val);
}
}
}
LandlockEnforceRuleset(ruleset);
SCFree(ruleset);
}
#endif /* HAVE_LINUX_LANDLOCK_H */
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