/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 1999 Marcel Moolenaar
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/cdefs.h>
#include <sys/param.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mount.h>
#include <sys/jail.h>
#include <sys/proc.h>
#include <sys/sx.h>

#include <compat/linux/linux_mib.h>
#include <compat/linux/linux_misc.h>

struct linux_prison {
	char	pr_osname[LINUX_MAX_UTSNAME];
	char	pr_osrelease[LINUX_MAX_UTSNAME];
	int	pr_oss_version;
	int	pr_osrel;
};

static struct linux_prison lprison0 = {
	.pr_osname =		"Linux",
	.pr_osrelease =		LINUX_VERSION_STR,
	.pr_oss_version =	0x030600,
	.pr_osrel =		LINUX_VERSION_CODE
};

static unsigned linux_osd_jail_slot;

SYSCTL_NODE(_compat, OID_AUTO, linux, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
    "Linux mode");

int linux_debug = 3;
SYSCTL_INT(_compat_linux, OID_AUTO, debug, CTLFLAG_RWTUN,
    &linux_debug, 0, "Log warnings from linux(4); or 0 to disable");

int linux_default_openfiles = 1024;
SYSCTL_INT(_compat_linux, OID_AUTO, default_openfiles, CTLFLAG_RWTUN,
    &linux_default_openfiles, 0,
    "Default soft openfiles resource limit, or -1 for unlimited");

int linux_default_stacksize = 8 * 1024 * 1024;
SYSCTL_INT(_compat_linux, OID_AUTO, default_stacksize, CTLFLAG_RWTUN,
    &linux_default_stacksize, 0,
    "Default soft stack size resource limit, or -1 for unlimited");

int linux_dummy_rlimits = 0;
SYSCTL_INT(_compat_linux, OID_AUTO, dummy_rlimits, CTLFLAG_RWTUN,
    &linux_dummy_rlimits, 0,
    "Return dummy values for unsupported Linux-specific rlimits");

int linux_ignore_ip_recverr = 1;
SYSCTL_INT(_compat_linux, OID_AUTO, ignore_ip_recverr, CTLFLAG_RWTUN,
    &linux_ignore_ip_recverr, 0, "Ignore enabling IP_RECVERR");

int linux_preserve_vstatus = 1;
SYSCTL_INT(_compat_linux, OID_AUTO, preserve_vstatus, CTLFLAG_RWTUN,
    &linux_preserve_vstatus, 0, "Preserve VSTATUS termios(4) flag");

bool linux_map_sched_prio = true;
SYSCTL_BOOL(_compat_linux, OID_AUTO, map_sched_prio, CTLFLAG_RDTUN,
    &linux_map_sched_prio, 0, "Map scheduler priorities to Linux priorities "
    "(not POSIX compliant)");

int linux_use_emul_path = 1;
SYSCTL_INT(_compat_linux, OID_AUTO, use_emul_path, CTLFLAG_RWTUN,
    &linux_use_emul_path, 0, "Use linux.compat.emul_path");

static bool linux_setid_allowed = true;
SYSCTL_BOOL(_compat_linux, OID_AUTO, setid_allowed, CTLFLAG_RWTUN,
    &linux_setid_allowed, 0,
    "Allow setuid/setgid on execve of Linux binary");

int
linux_setid_allowed_query(struct thread *td __unused,
    struct image_params *imgp __unused)
{
	return (linux_setid_allowed);
}

static int	linux_set_osname(struct thread *td, char *osname);
static int	linux_set_osrelease(struct thread *td, char *osrelease);
static int	linux_set_oss_version(struct thread *td, int oss_version);

static int
linux_sysctl_osname(SYSCTL_HANDLER_ARGS)
{
	char osname[LINUX_MAX_UTSNAME];
	int error;

	linux_get_osname(req->td, osname);
	error = sysctl_handle_string(oidp, osname, LINUX_MAX_UTSNAME, req);
	if (error != 0 || req->newptr == NULL)
		return (error);
	error = linux_set_osname(req->td, osname);

	return (error);
}

SYSCTL_PROC(_compat_linux, OID_AUTO, osname,
	    CTLTYPE_STRING | CTLFLAG_RW | CTLFLAG_PRISON | CTLFLAG_MPSAFE,
	    0, 0, linux_sysctl_osname, "A",
	    "Linux kernel OS name");

static int
linux_sysctl_osrelease(SYSCTL_HANDLER_ARGS)
{
	char osrelease[LINUX_MAX_UTSNAME];
	int error;

	linux_get_osrelease(req->td, osrelease);
	error = sysctl_handle_string(oidp, osrelease, LINUX_MAX_UTSNAME, req);
	if (error != 0 || req->newptr == NULL)
		return (error);
	error = linux_set_osrelease(req->td, osrelease);

	return (error);
}

SYSCTL_PROC(_compat_linux, OID_AUTO, osrelease,
	    CTLTYPE_STRING | CTLFLAG_RW | CTLFLAG_PRISON | CTLFLAG_MPSAFE,
	    0, 0, linux_sysctl_osrelease, "A",
	    "Linux kernel OS release");

static int
linux_sysctl_oss_version(SYSCTL_HANDLER_ARGS)
{
	int oss_version;
	int error;

	oss_version = linux_get_oss_version(req->td);
	error = sysctl_handle_int(oidp, &oss_version, 0, req);
	if (error != 0 || req->newptr == NULL)
		return (error);
	error = linux_set_oss_version(req->td, oss_version);

	return (error);
}

SYSCTL_PROC(_compat_linux, OID_AUTO, oss_version,
	    CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_PRISON | CTLFLAG_MPSAFE,
	    0, 0, linux_sysctl_oss_version, "I",
	    "Linux OSS version");

/*
 * Map the osrelease into integer
 */
static int
linux_map_osrel(char *osrelease, int *osrel)
{
	char *sep, *eosrelease;
	int len, v0, v1, v2, v;

	len = strlen(osrelease);
	eosrelease = osrelease + len;
	v0 = strtol(osrelease, &sep, 10);
	if (osrelease == sep || sep + 1 >= eosrelease || *sep != '.')
		return (EINVAL);
	osrelease = sep + 1;
	v1 = strtol(osrelease, &sep, 10);
	if (osrelease == sep || sep + 1 >= eosrelease || *sep != '.')
		return (EINVAL);
	osrelease = sep + 1;
	v2 = strtol(osrelease, &sep, 10);
	if (osrelease == sep ||
	    (sep != eosrelease && (sep + 1 >= eosrelease || *sep != '-')))
		return (EINVAL);

	v = LINUX_KERNVER(v0, v1, v2);
	if (v < LINUX_KERNVER(1, 0, 0))
		return (EINVAL);

	if (osrel != NULL)
		*osrel = v;

	return (0);
}

/*
 * Find a prison with Linux info.
 * Return the Linux info and the (locked) prison.
 */
static struct linux_prison *
linux_find_prison(struct prison *spr, struct prison **prp)
{
	struct prison *pr;
	struct linux_prison *lpr;

	for (pr = spr;; pr = pr->pr_parent) {
		mtx_lock(&pr->pr_mtx);
		lpr = (pr == &prison0)
		    ? &lprison0
		    : osd_jail_get(pr, linux_osd_jail_slot);
		if (lpr != NULL)
			break;
		mtx_unlock(&pr->pr_mtx);
	}
	*prp = pr;

	return (lpr);
}

/*
 * Ensure a prison has its own Linux info.  If lprp is non-null, point it to
 * the Linux info and lock the prison.
 */
static void
linux_alloc_prison(struct prison *pr, struct linux_prison **lprp)
{
	struct prison *ppr;
	struct linux_prison *lpr, *nlpr;
	void **rsv;

	/* If this prison already has Linux info, return that. */
	lpr = linux_find_prison(pr, &ppr);
	if (ppr == pr)
		goto done;
	/*
	 * Allocate a new info record.  Then check again, in case something
	 * changed during the allocation.
	 */
	mtx_unlock(&ppr->pr_mtx);
	nlpr = malloc(sizeof(struct linux_prison), M_PRISON, M_WAITOK);
	rsv = osd_reserve(linux_osd_jail_slot);
	lpr = linux_find_prison(pr, &ppr);
	if (ppr == pr) {
		free(nlpr, M_PRISON);
		osd_free_reserved(rsv);
		goto done;
	}
	/* Inherit the initial values from the ancestor. */
	mtx_lock(&pr->pr_mtx);
	(void)osd_jail_set_reserved(pr, linux_osd_jail_slot, rsv, nlpr);
	bcopy(lpr, nlpr, sizeof(*lpr));
	lpr = nlpr;
	mtx_unlock(&ppr->pr_mtx);
 done:
	if (lprp != NULL)
		*lprp = lpr;
	else
		mtx_unlock(&pr->pr_mtx);
}

/*
 * Jail OSD methods for Linux prison data.
 */
static int
linux_prison_create(void *obj, void *data)
{
	struct prison *pr = obj;
	struct vfsoptlist *opts = data;
	int jsys;

	if (vfs_copyopt(opts, "linux", &jsys, sizeof(jsys)) == 0 &&
	    jsys == JAIL_SYS_INHERIT)
		return (0);
	/*
	 * Inherit a prison's initial values from its parent
	 * (different from JAIL_SYS_INHERIT which also inherits changes).
	 */
	linux_alloc_prison(pr, NULL);
	return (0);
}

static int
linux_prison_check(void *obj __unused, void *data)
{
	struct vfsoptlist *opts = data;
	char *osname, *osrelease;
	int error, jsys, len, oss_version;

	/* Check that the parameters are correct. */
	error = vfs_copyopt(opts, "linux", &jsys, sizeof(jsys));
	if (error != ENOENT) {
		if (error != 0)
			return (error);
		if (jsys != JAIL_SYS_NEW && jsys != JAIL_SYS_INHERIT)
			return (EINVAL);
	}
	error = vfs_getopt(opts, "linux.osname", (void **)&osname, &len);
	if (error != ENOENT) {
		if (error != 0)
			return (error);
		if (len == 0 || osname[len - 1] != '\0')
			return (EINVAL);
		if (len > LINUX_MAX_UTSNAME) {
			vfs_opterror(opts, "linux.osname too long");
			return (ENAMETOOLONG);
		}
	}
	error = vfs_getopt(opts, "linux.osrelease", (void **)&osrelease, &len);
	if (error != ENOENT) {
		if (error != 0)
			return (error);
		if (len == 0 || osrelease[len - 1] != '\0')
			return (EINVAL);
		if (len > LINUX_MAX_UTSNAME) {
			vfs_opterror(opts, "linux.osrelease too long");
			return (ENAMETOOLONG);
		}
		error = linux_map_osrel(osrelease, NULL);
		if (error != 0) {
			vfs_opterror(opts, "linux.osrelease format error");
			return (error);
		}
	}
	error = vfs_copyopt(opts, "linux.oss_version", &oss_version,
	    sizeof(oss_version));

	if (error == ENOENT)
		error = 0;
	return (error);
}

static int
linux_prison_set(void *obj, void *data)
{
	struct linux_prison *lpr;
	struct prison *pr = obj;
	struct vfsoptlist *opts = data;
	char *osname, *osrelease;
	int error, gotversion, jsys, len, oss_version;

	/* Set the parameters, which should be correct. */
	error = vfs_copyopt(opts, "linux", &jsys, sizeof(jsys));
	if (error == ENOENT)
		jsys = -1;
	error = vfs_getopt(opts, "linux.osname", (void **)&osname, &len);
	if (error == ENOENT)
		osname = NULL;
	else
		jsys = JAIL_SYS_NEW;
	error = vfs_getopt(opts, "linux.osrelease", (void **)&osrelease, &len);
	if (error == ENOENT)
		osrelease = NULL;
	else
		jsys = JAIL_SYS_NEW;
	error = vfs_copyopt(opts, "linux.oss_version", &oss_version,
	    sizeof(oss_version));
	if (error == ENOENT)
		gotversion = 0;
	else {
		gotversion = 1;
		jsys = JAIL_SYS_NEW;
	}
	switch (jsys) {
	case JAIL_SYS_INHERIT:
		/* "linux=inherit": inherit the parent's Linux info. */
		mtx_lock(&pr->pr_mtx);
		osd_jail_del(pr, linux_osd_jail_slot);
		mtx_unlock(&pr->pr_mtx);
		break;
	case JAIL_SYS_NEW:
		/*
		 * "linux=new" or "linux.*":
		 * the prison gets its own Linux info.
		 */
		linux_alloc_prison(pr, &lpr);
		if (osrelease) {
			(void)linux_map_osrel(osrelease, &lpr->pr_osrel);
			strlcpy(lpr->pr_osrelease, osrelease,
			    LINUX_MAX_UTSNAME);
		}
		if (osname)
			strlcpy(lpr->pr_osname, osname, LINUX_MAX_UTSNAME);
		if (gotversion)
			lpr->pr_oss_version = oss_version;
		mtx_unlock(&pr->pr_mtx);
	}

	return (0);
}

SYSCTL_JAIL_PARAM_SYS_NODE(linux, CTLFLAG_RW, "Jail Linux parameters");
SYSCTL_JAIL_PARAM_STRING(_linux, osname, CTLFLAG_RW, LINUX_MAX_UTSNAME,
    "Jail Linux kernel OS name");
SYSCTL_JAIL_PARAM_STRING(_linux, osrelease, CTLFLAG_RW, LINUX_MAX_UTSNAME,
    "Jail Linux kernel OS release");
SYSCTL_JAIL_PARAM(_linux, oss_version, CTLTYPE_INT | CTLFLAG_RW,
    "I", "Jail Linux OSS version");

static int
linux_prison_get(void *obj, void *data)
{
	struct linux_prison *lpr;
	struct prison *ppr;
	struct prison *pr = obj;
	struct vfsoptlist *opts = data;
	int error, i;

	static int version0;

	/* See if this prison is the one with the Linux info. */
	lpr = linux_find_prison(pr, &ppr);
	i = (ppr == pr) ? JAIL_SYS_NEW : JAIL_SYS_INHERIT;
	error = vfs_setopt(opts, "linux", &i, sizeof(i));
	if (error != 0 && error != ENOENT)
		goto done;
	if (i) {
		error = vfs_setopts(opts, "linux.osname", lpr->pr_osname);
		if (error != 0 && error != ENOENT)
			goto done;
		error = vfs_setopts(opts, "linux.osrelease", lpr->pr_osrelease);
		if (error != 0 && error != ENOENT)
			goto done;
		error = vfs_setopt(opts, "linux.oss_version",
		    &lpr->pr_oss_version, sizeof(lpr->pr_oss_version));
		if (error != 0 && error != ENOENT)
			goto done;
	} else {
		/*
		 * If this prison is inheriting its Linux info, report
		 * empty/zero parameters.
		 */
		error = vfs_setopts(opts, "linux.osname", "");
		if (error != 0 && error != ENOENT)
			goto done;
		error = vfs_setopts(opts, "linux.osrelease", "");
		if (error != 0 && error != ENOENT)
			goto done;
		error = vfs_setopt(opts, "linux.oss_version", &version0,
		    sizeof(lpr->pr_oss_version));
		if (error != 0 && error != ENOENT)
			goto done;
	}
	error = 0;

 done:
	mtx_unlock(&ppr->pr_mtx);

	return (error);
}

static void
linux_prison_destructor(void *data)
{

	free(data, M_PRISON);
}

void
linux_osd_jail_register(void)
{
	struct prison *pr;
	osd_method_t methods[PR_MAXMETHOD] = {
	    [PR_METHOD_CREATE] =	linux_prison_create,
	    [PR_METHOD_GET] =		linux_prison_get,
	    [PR_METHOD_SET] =		linux_prison_set,
	    [PR_METHOD_CHECK] =		linux_prison_check
	};

	linux_osd_jail_slot =
	    osd_jail_register(linux_prison_destructor, methods);
	/* Copy the system Linux info to any current prisons. */
	sx_slock(&allprison_lock);
	TAILQ_FOREACH(pr, &allprison, pr_list)
		linux_alloc_prison(pr, NULL);
	sx_sunlock(&allprison_lock);
}

void
linux_osd_jail_deregister(void)
{

	osd_jail_deregister(linux_osd_jail_slot);
}

void
linux_get_osname(struct thread *td, char *dst)
{
	struct prison *pr;
	struct linux_prison *lpr;

	lpr = linux_find_prison(td->td_ucred->cr_prison, &pr);
	bcopy(lpr->pr_osname, dst, LINUX_MAX_UTSNAME);
	mtx_unlock(&pr->pr_mtx);
}

static int
linux_set_osname(struct thread *td, char *osname)
{
	struct prison *pr;
	struct linux_prison *lpr;

	lpr = linux_find_prison(td->td_ucred->cr_prison, &pr);
	strlcpy(lpr->pr_osname, osname, LINUX_MAX_UTSNAME);
	mtx_unlock(&pr->pr_mtx);

	return (0);
}

void
linux_get_osrelease(struct thread *td, char *dst)
{
	struct prison *pr;
	struct linux_prison *lpr;

	lpr = linux_find_prison(td->td_ucred->cr_prison, &pr);
	bcopy(lpr->pr_osrelease, dst, LINUX_MAX_UTSNAME);
	mtx_unlock(&pr->pr_mtx);
}

int
linux_kernver(struct thread *td)
{
	struct prison *pr;
	struct linux_prison *lpr;
	int osrel;

	lpr = linux_find_prison(td->td_ucred->cr_prison, &pr);
	osrel = lpr->pr_osrel;
	mtx_unlock(&pr->pr_mtx);

	return (osrel);
}

static int
linux_set_osrelease(struct thread *td, char *osrelease)
{
	struct prison *pr;
	struct linux_prison *lpr;
	int error;

	lpr = linux_find_prison(td->td_ucred->cr_prison, &pr);
	error = linux_map_osrel(osrelease, &lpr->pr_osrel);
	if (error == 0)
		strlcpy(lpr->pr_osrelease, osrelease, LINUX_MAX_UTSNAME);
	mtx_unlock(&pr->pr_mtx);

	return (error);
}

int
linux_get_oss_version(struct thread *td)
{
	struct prison *pr;
	struct linux_prison *lpr;
	int version;

	lpr = linux_find_prison(td->td_ucred->cr_prison, &pr);
	version = lpr->pr_oss_version;
	mtx_unlock(&pr->pr_mtx);

	return (version);
}

static int
linux_set_oss_version(struct thread *td, int oss_version)
{
	struct prison *pr;
	struct linux_prison *lpr;

	lpr = linux_find_prison(td->td_ucred->cr_prison, &pr);
	lpr->pr_oss_version = oss_version;
	mtx_unlock(&pr->pr_mtx);

	return (0);
}