/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
/*
 * Container Security Monitor module
 *
 * Copyright (c) 2018 Google, Inc
 */

#define pr_fmt(fmt)	"container-security-monitor: " fmt

#include <linux/kernel.h>
#include <linux/security.h>
#include <linux/fs.h>
#include <linux/rwsem.h>
#include <linux/binfmts.h>
#include <linux/xattr.h>
#include <config.pb.h>
#include <event.pb.h>
#include <pb_encode.h>
#include <pb_decode.h>

#include "monitoring_protocol.h"

/* Part of the CSM configuration response. */
#define CSM_VERSION 1

/* protects csm_*_enabled and configurations. */
extern struct rw_semaphore csm_rwsem_config;

/*
 * Is monitoring enabled? Defaults to disabled.
 * These variables might be used as gates without locking (as processor ensures
 * valid proper access for native scalar values) so it can bail quickly.
 */
extern bool csm_enabled;
extern bool csm_execute_enabled;
extern bool csm_memexec_enabled;

/* Configuration options for execute collector. */
struct execute_config {
	size_t argv_limit;
	size_t envp_limit;
	char *envp_allowlist;
};

extern struct execute_config csm_execute_config;

/* pipe to forward events to user-mode. */
extern struct rw_semaphore csm_rwsem_pipe;
extern struct file *csm_user_write_pipe;

/* Stats on LSM events. */
struct container_stats {
	size_t proto_encoding_failed;
	size_t event_writing_failed;
	size_t workqueue_failed;
	size_t size_picking_failed;
	size_t pipe_already_opened;
};

extern struct container_stats csm_stats;

/* Streams file numbers are unknown from the kernel */
#define STDIN_FILENO	0
#define STDOUT_FILENO	1
#define STDERR_FILENO	2

/* security attribute for file provenance. */
#define XATTR_SECURITY_CSM XATTR_SECURITY_PREFIX "csm"

/* monitor functions */
int csm_update_config_from_buffer(void *data, size_t size);

/* send event to userland */
int csm_sendeventproto(const pb_field_t fields[], schema_Event *event);

/* process events functions */
int csm_bprm_check_security(struct linux_binprm *bprm);
void csm_task_exit(struct task_struct *task);
void csm_task_post_alloc(struct task_struct *task);
int get_process_uuid_by_pid(pid_t pid_nr, char *buffer, size_t size);

/* memory execution events functions */
int csm_mprotect(struct vm_area_struct *vma, unsigned long reqprot,
					  unsigned long prot);
int csm_mmap_file(struct file *file, unsigned long reqprot,
				  unsigned long prot, unsigned long flags);

/* Tracking of file modification provenance. */
void csm_file_pre_free(struct file *file);

/* nano functions */
bool pb_encode_string_field(pb_ostream_t *stream, const pb_field_t *field,
			    void * const *arg);
bool pb_decode_string_field(pb_istream_t *stream, const pb_field_t *field,
		      void **arg);
ssize_t pb_encode_string_field_limit(pb_ostream_t *stream,
				     const pb_field_t *field,
				     void * const *arg, size_t limit);
bool pb_encode_string_array(pb_ostream_t *stream, const pb_field_t *field,
			    void * const *arg);
bool pb_decode_string_array(pb_istream_t *stream, const pb_field_t *field,
			    void **arg);
bool pb_encode_uuid_field(pb_ostream_t *stream, const pb_field_t *field,
			  void * const *arg);
bool pb_encode_ip4(pb_ostream_t *stream, const pb_field_t *field,
		   void * const *arg);
bool pb_encode_ip6(pb_ostream_t *stream, const pb_field_t *field,
		   void * const *arg);