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This Implements the mumbled about "Jail" feature. This is a seriously beefed up chroot kind of thing. The process is jailed along the same lines as a chroot does it, but with additional tough restrictions imposed on what the superuser can do. For all I know, it is safe to hand over the root bit inside a prison to the customer living in that prison, this is what it was developed for in fact: "real virtual servers". Each prison has an ip number associated with it, which all IP communications will be coerced to use and each prison has its own hostname. Needless to say, you need more RAM this way, but the advantage is that each customer can run their own particular version of apache and not stomp on the toes of their neighbors. It generally does what one would expect, but setting up a jail still takes a little knowledge. A few notes: I have no scripts for setting up a jail, don't ask me for them. The IP number should be an alias on one of the interfaces. mount a /proc in each jail, it will make ps more useable. /proc/<pid>/status tells the hostname of the prison for jailed processes. Quotas are only sensible if you have a mountpoint per prison. There are no privisions for stopping resource-hogging. Some "#ifdef INET" and similar may be missing (send patches!) If somebody wants to take it from here and develop it into more of a "virtual machine" they should be most welcome! Tools, comments, patches & documentation most welcome. Have fun... Sponsored by: http://www.rndassociates.com/ Run for almost a year by: http://www.servetheweb.com/
1999-04-28 11:38:52 +00:00
.\"
.\"----------------------------------------------------------------------------
.\""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
.\"----------------------------------------------------------------------------
.\"
Various man page cleanup: - Sort xrefs - FreeBSD.ORG -> FreeBSD.org - Be consistent with section names as outlines in mdoc(7) - Other misc mdoc cleanup. PR: doc/13144 Submitted by: Alexy M. Zelkin <phantom@cris.net>
1999-08-15 09:51:25 +00:00
.\"$Id: jail.2,v 1.4 1999/07/09 21:35:37 phk Exp $
This Implements the mumbled about "Jail" feature. This is a seriously beefed up chroot kind of thing. The process is jailed along the same lines as a chroot does it, but with additional tough restrictions imposed on what the superuser can do. For all I know, it is safe to hand over the root bit inside a prison to the customer living in that prison, this is what it was developed for in fact: "real virtual servers". Each prison has an ip number associated with it, which all IP communications will be coerced to use and each prison has its own hostname. Needless to say, you need more RAM this way, but the advantage is that each customer can run their own particular version of apache and not stomp on the toes of their neighbors. It generally does what one would expect, but setting up a jail still takes a little knowledge. A few notes: I have no scripts for setting up a jail, don't ask me for them. The IP number should be an alias on one of the interfaces. mount a /proc in each jail, it will make ps more useable. /proc/<pid>/status tells the hostname of the prison for jailed processes. Quotas are only sensible if you have a mountpoint per prison. There are no privisions for stopping resource-hogging. Some "#ifdef INET" and similar may be missing (send patches!) If somebody wants to take it from here and develop it into more of a "virtual machine" they should be most welcome! Tools, comments, patches & documentation most welcome. Have fun... Sponsored by: http://www.rndassociates.com/ Run for almost a year by: http://www.servetheweb.com/
1999-04-28 11:38:52 +00:00
.\"
.\"
.Dd April 28, 1999
.Dt JAIL 2
.Os FreeBSD 4.0
.Sh NAME
.Nm jail
.Nd Imprison current process and future decendants.
.Sh SYNOPSIS
.Fd #include <sys/types.h>
.Fd #include <sys/jail.h>
.Ft int
$ brucify -deblunder
1999-05-16 10:51:52 +00:00
.Fn jail "struct jail *jail"
This Implements the mumbled about "Jail" feature. This is a seriously beefed up chroot kind of thing. The process is jailed along the same lines as a chroot does it, but with additional tough restrictions imposed on what the superuser can do. For all I know, it is safe to hand over the root bit inside a prison to the customer living in that prison, this is what it was developed for in fact: "real virtual servers". Each prison has an ip number associated with it, which all IP communications will be coerced to use and each prison has its own hostname. Needless to say, you need more RAM this way, but the advantage is that each customer can run their own particular version of apache and not stomp on the toes of their neighbors. It generally does what one would expect, but setting up a jail still takes a little knowledge. A few notes: I have no scripts for setting up a jail, don't ask me for them. The IP number should be an alias on one of the interfaces. mount a /proc in each jail, it will make ps more useable. /proc/<pid>/status tells the hostname of the prison for jailed processes. Quotas are only sensible if you have a mountpoint per prison. There are no privisions for stopping resource-hogging. Some "#ifdef INET" and similar may be missing (send patches!) If somebody wants to take it from here and develop it into more of a "virtual machine" they should be most welcome! Tools, comments, patches & documentation most welcome. Have fun... Sponsored by: http://www.rndassociates.com/ Run for almost a year by: http://www.servetheweb.com/
1999-04-28 11:38:52 +00:00
.Sh DESCRIPTION
The
.Nm
system call sets up a jail and locks the current process in it.
.Pp
The argument is a pointer to a structure describing the prison:
.Bd -literal -offset indent
struct jail {
char *path;
char *hostname;
u_int32_t ip_number;
};
.Ed
.Pp
The
.Dq Li path
pointer should be set to the directory which is to be the root of the
prison.
.Pp
The
.Dq Li hostname
pointer can be set the hostname of the prison. This can be changed
from the inside of the prison.
.Pp
The
.Dq Li ip_number
can be set to the IP number assigned to the prison.
.Sh PRISON ?
Once a process has been put in a prison, it and its decendants cannot escape
the prison. It is not possible to add a process to a preexisting prison.
.Pp
Minor English corrections were made; SEE ALSO was also fixed (no commas).
1999-06-17 23:43:35 +00:00
Inside the prison, the concept of "superuser" is very diluted. In general,
it can be assumed that nothing can be mangled from inside a prison which
Clarify an explanation a little bit.
1999-07-09 21:35:37 +00:00
doesn't exist entirely inside that prison. For instance the directory
tree below
.Dq Li path
can be manipulated all the ways a root can normally do it, including
.Dq Li "rm -rf /*"
but new device special notes cannot be created because the reference
shared resources (the device drivers in the kernel).
This Implements the mumbled about "Jail" feature. This is a seriously beefed up chroot kind of thing. The process is jailed along the same lines as a chroot does it, but with additional tough restrictions imposed on what the superuser can do. For all I know, it is safe to hand over the root bit inside a prison to the customer living in that prison, this is what it was developed for in fact: "real virtual servers". Each prison has an ip number associated with it, which all IP communications will be coerced to use and each prison has its own hostname. Needless to say, you need more RAM this way, but the advantage is that each customer can run their own particular version of apache and not stomp on the toes of their neighbors. It generally does what one would expect, but setting up a jail still takes a little knowledge. A few notes: I have no scripts for setting up a jail, don't ask me for them. The IP number should be an alias on one of the interfaces. mount a /proc in each jail, it will make ps more useable. /proc/<pid>/status tells the hostname of the prison for jailed processes. Quotas are only sensible if you have a mountpoint per prison. There are no privisions for stopping resource-hogging. Some "#ifdef INET" and similar may be missing (send patches!) If somebody wants to take it from here and develop it into more of a "virtual machine" they should be most welcome! Tools, comments, patches & documentation most welcome. Have fun... Sponsored by: http://www.rndassociates.com/ Run for almost a year by: http://www.servetheweb.com/
1999-04-28 11:38:52 +00:00
.Pp
All IP activity will be forced to happen to/from the IP number specified,
Clarify an explanation a little bit.
1999-07-09 21:35:37 +00:00
which should be an alias on one of the network interfaces.
This Implements the mumbled about "Jail" feature. This is a seriously beefed up chroot kind of thing. The process is jailed along the same lines as a chroot does it, but with additional tough restrictions imposed on what the superuser can do. For all I know, it is safe to hand over the root bit inside a prison to the customer living in that prison, this is what it was developed for in fact: "real virtual servers". Each prison has an ip number associated with it, which all IP communications will be coerced to use and each prison has its own hostname. Needless to say, you need more RAM this way, but the advantage is that each customer can run their own particular version of apache and not stomp on the toes of their neighbors. It generally does what one would expect, but setting up a jail still takes a little knowledge. A few notes: I have no scripts for setting up a jail, don't ask me for them. The IP number should be an alias on one of the interfaces. mount a /proc in each jail, it will make ps more useable. /proc/<pid>/status tells the hostname of the prison for jailed processes. Quotas are only sensible if you have a mountpoint per prison. There are no privisions for stopping resource-hogging. Some "#ifdef INET" and similar may be missing (send patches!) If somebody wants to take it from here and develop it into more of a "virtual machine" they should be most welcome! Tools, comments, patches & documentation most welcome. Have fun... Sponsored by: http://www.rndassociates.com/ Run for almost a year by: http://www.servetheweb.com/
1999-04-28 11:38:52 +00:00
.Pp
It is possible to identify a process as jailed by examining
.Dq Li /proc/<pid>/status :
it will show a field near the end of the line, either as
a single hyphen for a process at large, or the hostname currently
set for the prison for jailed processes.
.Sh ERRORS
.Fn Jail
calls
.Xr chroot 2
internally, so the it can fail for all the same reasons.
Please consult the
.Xr chroot 2
manual page for details.
.Sh SEE ALSO
Various man page cleanup: - Sort xrefs - FreeBSD.ORG -> FreeBSD.org - Be consistent with section names as outlines in mdoc(7) - Other misc mdoc cleanup. PR: doc/13144 Submitted by: Alexy M. Zelkin <phantom@cris.net>
1999-08-15 09:51:25 +00:00
.Xr chdir 2 ,
.Xr chroot 2
This Implements the mumbled about "Jail" feature. This is a seriously beefed up chroot kind of thing. The process is jailed along the same lines as a chroot does it, but with additional tough restrictions imposed on what the superuser can do. For all I know, it is safe to hand over the root bit inside a prison to the customer living in that prison, this is what it was developed for in fact: "real virtual servers". Each prison has an ip number associated with it, which all IP communications will be coerced to use and each prison has its own hostname. Needless to say, you need more RAM this way, but the advantage is that each customer can run their own particular version of apache and not stomp on the toes of their neighbors. It generally does what one would expect, but setting up a jail still takes a little knowledge. A few notes: I have no scripts for setting up a jail, don't ask me for them. The IP number should be an alias on one of the interfaces. mount a /proc in each jail, it will make ps more useable. /proc/<pid>/status tells the hostname of the prison for jailed processes. Quotas are only sensible if you have a mountpoint per prison. There are no privisions for stopping resource-hogging. Some "#ifdef INET" and similar may be missing (send patches!) If somebody wants to take it from here and develop it into more of a "virtual machine" they should be most welcome! Tools, comments, patches & documentation most welcome. Have fun... Sponsored by: http://www.rndassociates.com/ Run for almost a year by: http://www.servetheweb.com/
1999-04-28 11:38:52 +00:00
.Sh HISTORY
The
.Fn jail
function call appeared in
.Fx 4.0 .
.Pp
Various man page cleanup: - Sort xrefs - FreeBSD.ORG -> FreeBSD.org - Be consistent with section names as outlines in mdoc(7) - Other misc mdoc cleanup. PR: doc/13144 Submitted by: Alexy M. Zelkin <phantom@cris.net>
1999-08-15 09:51:25 +00:00
The jail feature was written by
.An Poul-Henning Kamp
for R&D Associates
This Implements the mumbled about "Jail" feature. This is a seriously beefed up chroot kind of thing. The process is jailed along the same lines as a chroot does it, but with additional tough restrictions imposed on what the superuser can do. For all I know, it is safe to hand over the root bit inside a prison to the customer living in that prison, this is what it was developed for in fact: "real virtual servers". Each prison has an ip number associated with it, which all IP communications will be coerced to use and each prison has its own hostname. Needless to say, you need more RAM this way, but the advantage is that each customer can run their own particular version of apache and not stomp on the toes of their neighbors. It generally does what one would expect, but setting up a jail still takes a little knowledge. A few notes: I have no scripts for setting up a jail, don't ask me for them. The IP number should be an alias on one of the interfaces. mount a /proc in each jail, it will make ps more useable. /proc/<pid>/status tells the hostname of the prison for jailed processes. Quotas are only sensible if you have a mountpoint per prison. There are no privisions for stopping resource-hogging. Some "#ifdef INET" and similar may be missing (send patches!) If somebody wants to take it from here and develop it into more of a "virtual machine" they should be most welcome! Tools, comments, patches & documentation most welcome. Have fun... Sponsored by: http://www.rndassociates.com/ Run for almost a year by: http://www.servetheweb.com/
1999-04-28 11:38:52 +00:00
.Dq Li http://www.rndassociates.com/
who contributed it to FreeBSD.