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freebsd-dev/sys/kern/kern_jail.c
Mike Barcroft fd7a8150fb o In struct prison, add an allprison linked list of prisons (protected 
by allprison_mtx), a unique prison/jail identifier field, two path
  fields (pr_path for reporting and pr_root vnode instance) to store
  the chroot() point of each jail.
o Add jail_attach(2) to allow a process to bind to an existing jail.
o Add change_root() to perform the chroot operation on a specified
  vnode.
o Generalize change_dir() to accept a vnode, and move namei() calls
  to callers of change_dir().
o Add a new sysctl (security.jail.list) which is a group of
  struct xprison instances that represent a snapshot of active jails.

Reviewed by:	rwatson, tjr
2003-04-09 02:55:18 +00:00

457 lines
9.3 KiB
C
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/*
* ----------------------------------------------------------------------------
* "THE BEER-WARE LICENSE" (Revision 42):
* <phk@FreeBSD.ORG> wrote this file. As long as you retain this notice you
* can do whatever you want with this stuff. If we meet some day, and you think
* this stuff is worth it, you can buy me a beer in return. Poul-Henning Kamp
* ----------------------------------------------------------------------------
*
* $FreeBSD$
*
*/
#include <sys/param.h>
#include <sys/types.h>
#include <sys/kernel.h>
#include <sys/systm.h>
#include <sys/errno.h>
#include <sys/sysproto.h>
#include <sys/malloc.h>
#include <sys/proc.h>
#include <sys/jail.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/namei.h>
#include <sys/queue.h>
#include <sys/socket.h>
#include <sys/syscallsubr.h>
#include <sys/sysctl.h>
#include <sys/vnode.h>
#include <net/if.h>
#include <netinet/in.h>
MALLOC_DEFINE(M_PRISON, "prison", "Prison structures");
SYSCTL_DECL(_security);
SYSCTL_NODE(_security, OID_AUTO, jail, CTLFLAG_RW, 0,
"Jail rules");
mp_fixme("these variables need a lock")
int jail_set_hostname_allowed = 1;
SYSCTL_INT(_security_jail, OID_AUTO, set_hostname_allowed, CTLFLAG_RW,
&jail_set_hostname_allowed, 0,
"Processes in jail can set their hostnames");
int jail_socket_unixiproute_only = 1;
SYSCTL_INT(_security_jail, OID_AUTO, socket_unixiproute_only, CTLFLAG_RW,
&jail_socket_unixiproute_only, 0,
"Processes in jail are limited to creating UNIX/IPv4/route sockets only");
int jail_sysvipc_allowed = 0;
SYSCTL_INT(_security_jail, OID_AUTO, sysvipc_allowed, CTLFLAG_RW,
&jail_sysvipc_allowed, 0,
"Processes in jail can use System V IPC primitives");
/* allprison, lastprid, and prisoncount are protected by allprison_mtx. */
struct prisonlist allprison;
struct mtx allprison_mtx;
int lastprid = 0;
int prisoncount = 0;
static void init_prison(void *);
static struct prison *prison_find(int);
static int sysctl_jail_list(SYSCTL_HANDLER_ARGS);
static void
init_prison(void *data __unused)
{
mtx_init(&allprison_mtx, "allprison", NULL, MTX_DEF);
LIST_INIT(&allprison);
}
SYSINIT(prison, SI_SUB_INTRINSIC, SI_ORDER_ANY, init_prison, NULL);
/*
* MPSAFE
*/
int
jail(td, uap)
struct thread *td;
struct jail_args /* {
struct jail *jail;
} */ *uap;
{
struct nameidata nd;
struct prison *pr, *tpr;
struct jail j;
struct jail_attach_args jaa;
int error, tryprid;
error = copyin(uap->jail, &j, sizeof j);
if (error)
return (error);
if (j.version != 0)
return (EINVAL);
MALLOC(pr, struct prison *, sizeof *pr , M_PRISON, M_WAITOK | M_ZERO);
mtx_init(&pr->pr_mtx, "jail mutex", NULL, MTX_DEF);
pr->pr_ref = 1;
error = copyinstr(j.path, &pr->pr_path, sizeof pr->pr_path, 0);
if (error)
goto e_killmtx;
mtx_lock(&Giant);
NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF, UIO_SYSSPACE, pr->pr_path, td);
error = namei(&nd);
if (error) {
mtx_unlock(&Giant);
goto e_killmtx;
}
pr->pr_root = nd.ni_vp;
VOP_UNLOCK(nd.ni_vp, 0, td);
NDFREE(&nd, NDF_ONLY_PNBUF);
mtx_unlock(&Giant);
error = copyinstr(j.hostname, &pr->pr_host, sizeof pr->pr_host, 0);
if (error)
goto e_dropvnref;
pr->pr_ip = j.ip_number;
pr->pr_linux = NULL;
pr->pr_securelevel = securelevel;
/* Determine next pr_id and add prison to allprison list. */
mtx_lock(&allprison_mtx);
tryprid = lastprid + 1;
if (tryprid == JAIL_MAX)
tryprid = 1;
next:
LIST_FOREACH(tpr, &allprison, pr_list) {
if (tpr->pr_id == tryprid) {
tryprid++;
if (tryprid == JAIL_MAX) {
mtx_unlock(&allprison_mtx);
error = EAGAIN;
goto e_dropvnref;
}
goto next;
}
}
pr->pr_id = jaa.jid = lastprid = tryprid;
LIST_INSERT_HEAD(&allprison, pr, pr_list);
prisoncount++;
mtx_unlock(&allprison_mtx);
error = jail_attach(td, &jaa);
if (error)
goto e_dropprref;
mtx_lock(&pr->pr_mtx);
pr->pr_ref--;
mtx_unlock(&pr->pr_mtx);
td->td_retval[0] = jaa.jid;
return (0);
e_dropprref:
mtx_lock(&allprison_mtx);
LIST_REMOVE(pr, pr_list);
prisoncount--;
mtx_unlock(&allprison_mtx);
e_dropvnref:
mtx_lock(&Giant);
vrele(pr->pr_root);
mtx_unlock(&Giant);
e_killmtx:
mtx_destroy(&pr->pr_mtx);
FREE(pr, M_PRISON);
return (error);
}
/*
* MPSAFE
*/
int
jail_attach(td, uap)
struct thread *td;
struct jail_attach_args /* {
int jid;
} */ *uap;
{
struct proc *p;
struct ucred *newcred, *oldcred;
struct prison *pr;
int error;
p = td->td_proc;
mtx_lock(&allprison_mtx);
pr = prison_find(uap->jid);
if (pr == NULL) {
mtx_unlock(&allprison_mtx);
return (EINVAL);
}
pr->pr_ref++;
mtx_unlock(&pr->pr_mtx);
mtx_unlock(&allprison_mtx);
error = suser_cred(td->td_ucred, PRISON_ROOT);
if (error)
goto e_dropref;
mtx_lock(&Giant);
vn_lock(pr->pr_root, LK_EXCLUSIVE | LK_RETRY, td);
if ((error = change_dir(pr->pr_root, td)) != 0)
goto e_unlock;
#ifdef MAC
if ((error = mac_check_vnode_chroot(td->td_ucred, pr->pr_root)))
goto e_unlock;
#endif
VOP_UNLOCK(pr->pr_root, 0, td);
change_root(pr->pr_root, td);
mtx_unlock(&Giant);
newcred = crget();
PROC_LOCK(p);
/* Implicitly fail if already in jail. */
error = suser_cred(p->p_ucred, 0);
if (error) {
PROC_UNLOCK(p);
crfree(newcred);
goto e_dropref;
}
oldcred = p->p_ucred;
setsugid(p);
crcopy(newcred, oldcred);
p->p_ucred = newcred;
mtx_lock(&pr->pr_mtx);
p->p_ucred->cr_prison = pr;
mtx_unlock(&pr->pr_mtx);
PROC_UNLOCK(p);
crfree(oldcred);
return (0);
e_unlock:
VOP_UNLOCK(pr->pr_root, 0, td);
mtx_unlock(&Giant);
e_dropref:
mtx_lock(&pr->pr_mtx);
pr->pr_ref--;
mtx_unlock(&pr->pr_mtx);
return (error);
}
/*
* Returns a locked prison instance, or NULL on failure.
*/
static struct prison *
prison_find(int prid)
{
struct prison *pr;
mtx_assert(&allprison_mtx, MA_OWNED);
LIST_FOREACH(pr, &allprison, pr_list) {
if (pr->pr_id == prid) {
mtx_lock(&pr->pr_mtx);
return (pr);
}
}
return (NULL);
}
void
prison_free(struct prison *pr)
{
mtx_assert(&Giant, MA_OWNED);
mtx_lock(&allprison_mtx);
mtx_lock(&pr->pr_mtx);
pr->pr_ref--;
if (pr->pr_ref == 0) {
LIST_REMOVE(pr, pr_list);
mtx_unlock(&pr->pr_mtx);
prisoncount--;
mtx_unlock(&allprison_mtx);
vrele(pr->pr_root);
mtx_destroy(&pr->pr_mtx);
if (pr->pr_linux != NULL)
FREE(pr->pr_linux, M_PRISON);
FREE(pr, M_PRISON);
return;
}
mtx_unlock(&pr->pr_mtx);
mtx_unlock(&allprison_mtx);
}
void
prison_hold(struct prison *pr)
{
mtx_lock(&pr->pr_mtx);
pr->pr_ref++;
mtx_unlock(&pr->pr_mtx);
}
u_int32_t
prison_getip(struct ucred *cred)
{
return (cred->cr_prison->pr_ip);
}
int
prison_ip(struct ucred *cred, int flag, u_int32_t *ip)
{
u_int32_t tmp;
if (!jailed(cred))
return (0);
if (flag)
tmp = *ip;
else
tmp = ntohl(*ip);
if (tmp == INADDR_ANY) {
if (flag)
*ip = cred->cr_prison->pr_ip;
else
*ip = htonl(cred->cr_prison->pr_ip);
return (0);
}
if (tmp == INADDR_LOOPBACK) {
if (flag)
*ip = cred->cr_prison->pr_ip;
else
*ip = htonl(cred->cr_prison->pr_ip);
return (0);
}
if (cred->cr_prison->pr_ip != tmp)
return (1);
return (0);
}
void
prison_remote_ip(struct ucred *cred, int flag, u_int32_t *ip)
{
u_int32_t tmp;
if (!jailed(cred))
return;
if (flag)
tmp = *ip;
else
tmp = ntohl(*ip);
if (tmp == INADDR_LOOPBACK) {
if (flag)
*ip = cred->cr_prison->pr_ip;
else
*ip = htonl(cred->cr_prison->pr_ip);
return;
}
return;
}
int
prison_if(struct ucred *cred, struct sockaddr *sa)
{
struct sockaddr_in *sai = (struct sockaddr_in*) sa;
int ok;
if ((sai->sin_family != AF_INET) && jail_socket_unixiproute_only)
ok = 1;
else if (sai->sin_family != AF_INET)
ok = 0;
else if (cred->cr_prison->pr_ip != ntohl(sai->sin_addr.s_addr))
ok = 1;
else
ok = 0;
return (ok);
}
/*
* Return 0 if jails permit p1 to frob p2, otherwise ESRCH.
*/
int
prison_check(cred1, cred2)
struct ucred *cred1, *cred2;
{
if (jailed(cred1)) {
if (!jailed(cred2))
return (ESRCH);
if (cred2->cr_prison != cred1->cr_prison)
return (ESRCH);
}
return (0);
}
/*
* Return 1 if the passed credential is in a jail, otherwise 0.
*/
int
jailed(cred)
struct ucred *cred;
{
return (cred->cr_prison != NULL);
}
/*
* Return the correct hostname for the passed credential.
*/
void
getcredhostname(cred, buf, size)
struct ucred *cred;
char *buf;
size_t size;
{
if (jailed(cred)) {
mtx_lock(&cred->cr_prison->pr_mtx);
strlcpy(buf, cred->cr_prison->pr_host, size);
mtx_unlock(&cred->cr_prison->pr_mtx);
}
else
strlcpy(buf, hostname, size);
}
static int
sysctl_jail_list(SYSCTL_HANDLER_ARGS)
{
struct xprison *xp, *sxp;
struct prison *pr;
int count, error;
mtx_assert(&Giant, MA_OWNED);
retry:
mtx_lock(&allprison_mtx);
count = prisoncount;
mtx_unlock(&allprison_mtx);
if (count == 0)
return (0);
sxp = xp = malloc(sizeof(*xp) * count, M_TEMP, M_WAITOK | M_ZERO);
mtx_lock(&allprison_mtx);
if (count != prisoncount) {
mtx_unlock(&allprison_mtx);
free(sxp, M_TEMP);
goto retry;
}
LIST_FOREACH(pr, &allprison, pr_list) {
mtx_lock(&pr->pr_mtx);
xp->pr_version = XPRISON_VERSION;
xp->pr_id = pr->pr_id;
strlcpy(xp->pr_path, pr->pr_path, sizeof(xp->pr_path));
strlcpy(xp->pr_host, pr->pr_host, sizeof(xp->pr_host));
xp->pr_ip = pr->pr_ip;
mtx_unlock(&pr->pr_mtx);
xp++;
}
mtx_unlock(&allprison_mtx);
error = SYSCTL_OUT(req, sxp, sizeof(*sxp) * count);
free(sxp, M_TEMP);
if (error)
return (error);
return (0);
}
SYSCTL_OID(_security_jail, OID_AUTO, list, CTLTYPE_STRUCT | CTLFLAG_RD,
NULL, 0, sysctl_jail_list, "S", "List of active jails");
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