Date: Tue, 8 Feb 2011 17:30:32 +0100 From: Julian Fagir <gnrp@gnrp.in-berlin.de> To: freebsd-jail@freebsd.org Subject: Getting hostname from jail_getid(3) or ezjail(5) Message-ID: <20110208173032.38e0a073@adolfputzen>
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Hi,
I wanted to write a tool starting a shell in a jail. I know, jexec
accomplishes this too, but I want to compile the name of the jail into the
program, no commandline-parameters (more about this topic will be posted on
this list soon).
Thus, I used libjail, more specific jail_getid(3) to get the id of the jail
and start a shell in it.
The name of the jail is 'jail2', it was created by ezjail(5), and the
important lines in /usr/local/etc/ezjail/jail2 are:
export jail_jail2_hostname=3D"zweihorn2"
export jail_jail2_ip=3D"IPADDRESS"
export jail_jail22_rootdir=3D"/usr/jails/jail2"
Anyway, when starting the jail, `jls` bravely shows as the hostname of the
jail 'jail2'.
But when I compile this program (with `cc -ljail jexec_sh.c -o jexec_sh`)
#include <sys/types.h>
#include <sys/param.h>
#include <sys/jail.h>
#include <string.h>
#include <unistd.h>
#include <stdio.h>
#include <jail.h>
#define JAIL_NAME "jail2"
int
main(int argc, char* argv[]) {
char *jname;
int jid;
jid =3D jail_getid(JAIL_NAME);
printf("Jail 2 is running: %d\n", jid);
jname =3D jail_getname(jid);
printf("Jailname: '%s' to jid %d\n", jname, jid);
return(0);
}
jail_getid returns -1; meaning the jailname does not exist. When setting
JAIL_NAME to "1" (or "2", etc., according to the jid, if I restarted it), t=
he
jid is correctly returned:
zweihorn1# /home/julian/jexec_sh
Jail 1 is running: 1
Jailname: '1' to jid 1
Am i missing something? jail_getid/jail_getname should return exactly the
output I expected?! ezjail must be setting the name right as jls returns the
correct name. jls does nearly the same, though requesting directly the para=
ms
without libjail, but libjail does that internally, too.
Regards, Julian
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