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Diffstat (limited to 'lib/libc/sys/jail.2')
| -rw-r--r-- | lib/libc/sys/jail.2 | 105 |
1 files changed, 105 insertions, 0 deletions
diff --git a/lib/libc/sys/jail.2 b/lib/libc/sys/jail.2 new file mode 100644 index 0000000..00aae7e --- /dev/null +++ b/lib/libc/sys/jail.2 @@ -0,0 +1,105 @@ +.\" +.\"---------------------------------------------------------------------------- +.\""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 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 +.Fn jail "struct jail *jail" +.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 { + 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 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 +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 +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). +.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 +.Fn jail +will fail if: +.Bl -tag -width EWOULDBLOCK +.It Bq Er EINVAL +The version number of the argument is not correct. +.El +Further +.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 +.Xr chdir 2 , +.Xr chroot 2 +.Sh HISTORY +The +.Fn jail +function call appeared in +.Fx 4.0 . +.Pp +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 . |
