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/*
* Copyright (C) 2026 Daniel Golle <daniel@makrotopia.org>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License version 2.1
* 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.
*/
#define _GNU_SOURCE
#include <errno.h>
#include <fcntl.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/syscall.h>
#include <linux/landlock.h>
#include "log.h"
#include "landlock.h"
static int landlock_abi_cached = -2;
static int sys_landlock_create_ruleset(const struct landlock_ruleset_attr *attr,
size_t size, uint32_t flags)
{
return syscall(SYS_landlock_create_ruleset, attr, size, flags);
}
static int sys_landlock_add_rule(int ruleset_fd, enum landlock_rule_type type,
const void *rule_attr, uint32_t flags)
{
return syscall(SYS_landlock_add_rule, ruleset_fd, type, rule_attr, flags);
}
static int sys_landlock_restrict_self(int ruleset_fd, uint32_t flags)
{
return syscall(SYS_landlock_restrict_self, ruleset_fd, flags);
}
static int landlock_abi(void)
{
if (landlock_abi_cached == -2)
landlock_abi_cached = sys_landlock_create_ruleset(NULL, 0,
LANDLOCK_CREATE_RULESET_VERSION);
return landlock_abi_cached;
}
bool landlock_available(void)
{
return landlock_abi() >= 1;
}
int landlock_config_add(struct landlock_config *cfg, const char *path, uint64_t access)
{
struct landlock_rule *r;
r = realloc(cfg->rules, sizeof(*r) * (cfg->n + 1));
if (!r)
return -ENOMEM;
cfg->rules = r;
r[cfg->n].path = strdup(path);
if (!r[cfg->n].path)
return -ENOMEM;
r[cfg->n].access = access;
cfg->n++;
return 0;
}
int landlock_config_add_paths(struct landlock_config *cfg, const char *paths,
uint64_t access)
{
char *dup, *tok, *save;
int rc = 0;
if (!paths || !*paths)
return 0;
dup = strdup(paths);
if (!dup)
return -ENOMEM;
for (tok = strtok_r(dup, ":", &save); tok; tok = strtok_r(NULL, ":", &save)) {
rc = landlock_config_add(cfg, tok, access);
if (rc)
break;
}
free(dup);
return rc;
}
int landlock_apply(const struct landlock_config *cfg)
{
struct landlock_ruleset_attr ra = { 0 };
int ruleset_fd, rc = 0;
size_t i;
if (cfg->n == 0)
return 0;
if (!landlock_available())
return -ENOSYS;
for (i = 0; i < cfg->n; i++)
ra.handled_access_fs |= cfg->rules[i].access;
ruleset_fd = sys_landlock_create_ruleset(&ra, sizeof(ra), 0);
if (ruleset_fd < 0) {
int saved_errno = errno;
ERROR("landlock_create_ruleset: %s\n", strerror(saved_errno));
return -saved_errno;
}
for (i = 0; i < cfg->n; i++) {
struct landlock_path_beneath_attr pa = {
.allowed_access = cfg->rules[i].access,
};
int saved_errno;
pa.parent_fd = open(cfg->rules[i].path, O_PATH | O_CLOEXEC);
if (pa.parent_fd < 0) {
saved_errno = errno;
ERROR("landlock: open(%s): %s\n", cfg->rules[i].path,
strerror(saved_errno));
rc = -saved_errno;
goto out;
}
if (sys_landlock_add_rule(ruleset_fd, LANDLOCK_RULE_PATH_BENEATH,
&pa, 0)) {
saved_errno = errno;
ERROR("landlock_add_rule(%s): %s\n", cfg->rules[i].path,
strerror(saved_errno));
rc = -saved_errno;
close(pa.parent_fd);
goto out;
}
close(pa.parent_fd);
}
if (sys_landlock_restrict_self(ruleset_fd, 0)) {
int saved_errno = errno;
ERROR("landlock_restrict_self: %s\n", strerror(saved_errno));
rc = -saved_errno;
}
out:
close(ruleset_fd);
return rc;
}
void landlock_config_free(struct landlock_config *cfg)
{
size_t i;
for (i = 0; i < cfg->n; i++)
free(cfg->rules[i].path);
free(cfg->rules);
cfg->rules = NULL;
cfg->n = 0;
}
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