Re: sysctl node names (Re: CVS commit: src/sys/uvm)

[Patrick Welche <prlw1%cam.ac.uk@localhost>]

On Fri, Feb 19, 2010 at 05:44:48AM +0000, YAMAMOTO Takashi wrote:
> hi,
> 
> > Module Name:        src
> > Committed By:       drochner
> > Date:               Thu Feb 18 14:57:01 UTC 2010
> > 
> > Modified Files:
> >     src/sys/uvm: files.uvm uvm_map.c
> > 
> > Log Message:
> > Disable mapping of virtual address 0 by user programs per default.
> > This blocks an easy exploit of kernel bugs leading to dereference
> > of a NULL pointer on some architectures (eg i386).
> > The check can be disabled in various ways:
> > -by CPP definitions in machine/types.h (portmaster's choice)
> > -by a kernel config option USER_VA0_DISABLED_DEFAULT=0
> > -at runtime by sysctl vm.user_va0_disabled (cannot be cleared
> >  at securelevel>0)
> 
> it reminded me this...
> 
> can we have some policy for future sysctl node names?
> the current mixture of "enable" vs "enabled" seems ugly to me.
> if my preference matters, i'd say "enable"/"disable".
> 
> YAMAMOTO Takashi
> 
> ushi% sysctl -a|grep enable
> net.inet.tcp.sack.enable = 1
> net.inet.tcp.ecn.enable = 0
> net.inet.tcp.abc.enable = 1
> net.inet6.tcp6.sack.enable = 1
> net.inet6.tcp6.ecn.enable = 0
> net.inet6.tcp6.abc.enable = 1
> hw.fwohci.phydma_enable = 1
> security.pax.mprotect.enabled = 1
> security.pax.aslr.enabled = 1
> ushi% 

Which reminds me of sys/sysctl.h

#define CTLTYPE_BOOL    6       /* name describes a bool */

but bool doesn't seem to have i/o routines (I bet that all the above
are CTLTYPE_INT) And then what would be output for bool 1, t, true, vrai...

Cheers,

Patrick