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Diffstat (limited to 'lib/libc/sys/jail.2')
| -rw-r--r-- | lib/libc/sys/jail.2 | 142 |
1 files changed, 142 insertions, 0 deletions
diff --git a/lib/libc/sys/jail.2 b/lib/libc/sys/jail.2 new file mode 100644 index 0000000..5cba4bf --- /dev/null +++ b/lib/libc/sys/jail.2 @@ -0,0 +1,142 @@ +.\" +.\" ---------------------------------------------------------------------------- +.\" "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 +.\" ---------------------------------------------------------------------------- +.\" +.\" $FreeBSD$ +.\" +.Dd April 8, 2003 +.Dt JAIL 2 +.Os +.Sh NAME +.Nm jail , jail_attach +.Nd imprison current process and future descendants +.Sh LIBRARY +.Lb libc +.Sh SYNOPSIS +.In sys/param.h +.In sys/jail.h +.Ft int +.Fn jail "struct jail *jail" +.Ft int +.Fn jail_attach "int jid" +.Sh DESCRIPTION +The +.Fn jail +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 { + u_int32_t version; + char *path; + char *hostname; + u_int32_t ip_number; +}; +.Ed +.Pp +.Dq Li version +defines the version of the API in use. +It should be set to zero at this time. +.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 to 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. +.Pp +The +.Fn jail_attach +system call attaches the current process to an existing jail, +identified by +.Fa jid . +.Sh RETURN VALUES +If successful, +.Fn jail +returns a non-negative integer, termed the jail identifier (JID). +It returns \-1 on failure, and sets +.Va errno +to indicate the error. +.Pp +.Rv -std jail_attach +.Sh PRISON? +Once a process has been put in a prison, it and its descendants cannot escape +the prison. +.Pp +Inside the prison, the concept of +.Dq superuser +is very diluted. +In general, +it can be assumed that nothing can be mangled from inside a prison which +does not 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 nodes cannot be created because they reference +shared resources (the device drivers in the kernel). +The effective +.Dq securelevel +for a process is the greater of the global +.Dq securelevel +or, if present, the per-jail +.Dq securelevel . +.Pp +All IP activity will be forced to happen to/from the IP number specified, +which should be an alias on one of the network interfaces. +.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 +The +.Fn jail +system call +will fail if: +.Bl -tag -width Er +.It Bq Er EINVAL +The version number of the argument is not correct. +.El +.Pp +Further +.Fn jail +calls +.Xr chroot 2 +internally, so it can fail for all the same reasons. +Please consult the +.Xr chroot 2 +manual page for details. +.Sh SEE ALSO +.Xr chdir 2 , +.Xr chroot 2 +.Sh HISTORY +The +.Fn jail +system call appeared in +.Fx 4.0 . +The +.Fn jail_attach +system call appeared in +.Fx 5.1 . +.Sh AUTHORS +The jail feature was written by +.An Poul-Henning Kamp +for R&D Associates +.Dq Li http://www.rndassociates.com/ +who contributed it to +.Fx . |
