text: /*-
   * ----------------------------------------------------------------------------
   * "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
   * ----------------------------------------------------------------------------
   */
  
  #include <sys/cdefs.h>
  __FBSDID("$FreeBSD: src/sys/kern/kern_jail.c,v 1.51 2005/09/28 00:30:56 csjp Exp $");
  
  #include "opt_mac.h"
  
  #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/mac.h>
  #include <sys/malloc.h>
  #include <sys/proc.h>
  #include <sys/taskqueue.h>
  #include <sys/jail.h>
  #include <sys/lock.h>
  #include <sys/mutex.h>
  #include <sys/namei.h>
  #include <sys/mount.h>
  #include <sys/queue.h>
  #include <sys/socket.h>
  #include <sys/syscallsubr.h>
  #include <sys/sysctl.h>
  #include <sys/vnode.h>
  #include <sys/capability.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");
  
  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");
  
  static int jail_enforce_statfs = 2;
  SYSCTL_INT(_security_jail, OID_AUTO, enforce_statfs, CTLFLAG_RW,
      &jail_enforce_statfs, 0,
      "Processes in jail cannot see all mounted file systems");
  
  int	jail_allow_raw_sockets = 0;
  SYSCTL_INT(_security_jail, OID_AUTO, allow_raw_sockets, CTLFLAG_RW,
      &jail_allow_raw_sockets, 0,
      "Prison root can create raw sockets");
  
  int	jail_chflags_allowed = 0;
  SYSCTL_INT(_security_jail, OID_AUTO, chflags_allowed, CTLFLAG_RW,
      &jail_chflags_allowed, 0,
      "Processes in jail can alter system file flags");
  
  /* 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 void		 prison_complete(void *context, int pending);
  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
   *
   * struct jail_args {
   *	struct jail *jail;
   * };
   */
  int
  jail(struct thread *td, struct jail_args *uap)
  {
  	struct nameidata nd;
  	struct prison *pr, *tpr;
  	struct jail j;
  	struct jail_attach_args jaa;
  	int vfslocked, 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;
  	NDINIT(&nd, LOOKUP, MPSAFE | FOLLOW | LOCKLEAF, UIO_SYSSPACE,
  	    pr->pr_path, td);
  	error = namei(&nd);
  	if (error)
  		goto e_killmtx;
  	vfslocked = NDHASGIANT(&nd);
  	pr->pr_root = nd.ni_vp;
  	VOP_UNLOCK(nd.ni_vp, 0, td);
  	NDFREE(&nd, NDF_ONLY_PNBUF);
  	VFS_UNLOCK_GIANT(vfslocked);
  	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:
  	vfslocked = VFS_LOCK_GIANT(pr->pr_root->v_mount);
  	vrele(pr->pr_root);
  	VFS_UNLOCK_GIANT(vfslocked);
  e_killmtx:
  	mtx_destroy(&pr->pr_mtx);
  	FREE(pr, M_PRISON);
  	return (error);
  }
  
  /*
   * MPSAFE
   *
   * struct jail_attach_args {
   *	int jid;
   * };
   */
  int
  jail_attach(struct thread *td, struct jail_attach_args *uap)
  {
  	struct proc *p;
  	struct ucred *newcred, *oldcred;
  	struct prison *pr;
  	int vfslocked, error;
  	
  	/*
  	 * XXX: Note that there is a slight race here if two threads
  	 * in the same privileged process attempt to attach to two
  	 * different jails at the same time.  It is important for
  	 * user processes not to do this, or they might end up with
  	 * a process root from one prison, but attached to the jail
  	 * of another.
  	 */
  	error = cap_check(td, CAP_SYS_CHROOT);
  	if (error)
  		return (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);
  
  	vfslocked = VFS_LOCK_GIANT(pr->pr_root->v_mount);
  	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);
  	VFS_UNLOCK_GIANT(vfslocked);
  
  	newcred = crget();
  	PROC_LOCK(p);
  	oldcred = p->p_ucred;
  	setsugid(p);
  	crcopy(newcred, oldcred);
  	newcred->cr_prison = pr;
  	p->p_ucred = newcred;
  	PROC_UNLOCK(p);
  	crfree(oldcred);
  	return (0);
  e_unlock:
  	VOP_UNLOCK(pr->pr_root, 0, td);
  	VFS_UNLOCK_GIANT(vfslocked);
  	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_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);
  
  		TASK_INIT(&pr->pr_task, 0, prison_complete, pr);
  		taskqueue_enqueue(taskqueue_thread, &pr->pr_task);
  		return;
  	}
  	mtx_unlock(&pr->pr_mtx);
  	mtx_unlock(&allprison_mtx);
  }
  
  static void
  prison_complete(void *context, int pending)
  {
  	struct prison *pr;
  	int vfslocked;
  
  	pr = (struct prison *)context;
  
  	vfslocked = VFS_LOCK_GIANT(pr->pr_root->v_mount);
  	vrele(pr->pr_root);
  	VFS_UNLOCK_GIANT(vfslocked);
  
  	mtx_destroy(&pr->pr_mtx);
  	if (pr->pr_linux != NULL)
  		FREE(pr->pr_linux, M_PRISON);
  	FREE(pr, M_PRISON);
  }
  
  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;
  	int ok;
  
  	sai = (struct sockaddr_in *)sa;
  	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(struct ucred *cred1, struct ucred *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(struct ucred *cred)
  {
  
  	return (cred->cr_prison != NULL);
  }
  
  /*
   * Return the correct hostname for the passed credential.
   */
  void
  getcredhostname(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);
  }
  
  /*
   * Determine whether the subject represented by cred can "see"
   * status of a mount point.
   * Returns: 0 for permitted, ENOENT otherwise.
   * XXX: This function should be called cr_canseemount() and should be
   *      placed in kern_prot.c.
   */
  int
  prison_canseemount(struct ucred *cred, struct mount *mp)
  {
  	struct prison *pr;
  	struct statfs *sp;
  	size_t len;
  
  	if (!jailed(cred) || jail_enforce_statfs == 0)
  		return (0);
  	pr = cred->cr_prison;
  	if (pr->pr_root->v_mount == mp)
  		return (0);
  	if (jail_enforce_statfs == 2)
  		return (ENOENT);
  	/*
  	 * If jail's chroot directory is set to "/" we should be able to see
  	 * all mount-points from inside a jail.
  	 * This is ugly check, but this is the only situation when jail's
  	 * directory ends with '/'.
  	 */
  	if (strcmp(pr->pr_path, "/") == 0)
  		return (0);
  	len = strlen(pr->pr_path);
  	sp = &mp->mnt_stat;
  	if (strncmp(pr->pr_path, sp->f_mntonname, len) != 0)
  		return (ENOENT);
  	/*
  	 * Be sure that we don't have situation where jail's root directory
  	 * is "/some/path" and mount point is "/some/pathpath".
  	 */
  	if (sp->f_mntonname[len] != '\0' && sp->f_mntonname[len] != '/')
  		return (ENOENT);
  	return (0);
  }
  
  void
  prison_enforce_statfs(struct ucred *cred, struct mount *mp, struct statfs *sp)
  {
  	char jpath[MAXPATHLEN];
  	struct prison *pr;
  	size_t len;
  
  	if (!jailed(cred) || jail_enforce_statfs == 0)
  		return;
  	pr = cred->cr_prison;
  	if (prison_canseemount(cred, mp) != 0) {
  		bzero(sp->f_mntonname, sizeof(sp->f_mntonname));
  		strlcpy(sp->f_mntonname, "[restricted]",
  		    sizeof(sp->f_mntonname));
  		return;
  	}
  	if (pr->pr_root->v_mount == mp) {
  		/*
  		 * Clear current buffer data, so we are sure nothing from
  		 * the valid path left there.
  		 */
  		bzero(sp->f_mntonname, sizeof(sp->f_mntonname));
  		*sp->f_mntonname = '/';
  		return;
  	}
  	/*
  	 * If jail's chroot directory is set to "/" we should be able to see
  	 * all mount-points from inside a jail.
  	 */
  	if (strcmp(pr->pr_path, "/") == 0)
  		return;
  	len = strlen(pr->pr_path);
  	strlcpy(jpath, sp->f_mntonname + len, sizeof(jpath));
  	/*
  	 * Clear current buffer data, so we are sure nothing from
  	 * the valid path left there.
  	 */
  	bzero(sp->f_mntonname, sizeof(sp->f_mntonname));
  	if (*jpath == '\0') {
  		/* Should never happen. */
  		*sp->f_mntonname = '/';
  	} else {
  		strlcpy(sp->f_mntonname, jpath, sizeof(sp->f_mntonname));
  	}
  }
  
  static int
  sysctl_jail_list(SYSCTL_HANDLER_ARGS)
  {
  	struct xprison *xp, *sxp;
  	struct prison *pr;
  	int count, error;
  
  	if (jailed(req->td->td_ucred))
  		return (0);
  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");
  
  static int
  sysctl_jail_jailed(SYSCTL_HANDLER_ARGS)
  {
  	int error, injail;
  
  	injail = jailed(req->td->td_ucred);
  	error = SYSCTL_OUT(req, &injail, sizeof(injail));
  
  	return (error);
  }
  SYSCTL_PROC(_security_jail, OID_AUTO, jailed, CTLTYPE_INT | CTLFLAG_RD,
      NULL, 0, sysctl_jail_jailed, "I", "Process in jail?");
  