PERFORCE change 99406 for review

[Divacky Roman]

On Mon, Jun 19, 2006 at 10:02:25AM -0400, John Baldwin wrote:
> On Saturday 17 June 2006 04:57, Roman Divacky wrote:
> > http://perforce.freebsd.org/chv.cgi?CH=99406
> > 
> > Change 99406 by rdivacky at rdivacky_witten on 2006/06/17 08:56:59
> > 
> > 	Change the emulpath sysctl to be per-prison.
> > 
> > ==== //depot/projects/soc2006/rdivacky_linuxolator/compat/linux/linux_mib.c#3 (text+ko) ====
> > 
> > @@ -90,7 +90,7 @@
> >  static int
> >  linux_sysctl_linux_emul_path(SYSCTL_HANDLER_ARGS)
> >  {
> > -           char emul_path[LINUX_NAME_MAX];
> > +           static char emul_path[LINUX_NAME_MAX];
> >  	   int error;
> >  	   Elf32_Brandinfo **brandinfo;
> >  
> > @@ -99,10 +99,39 @@
> >  	   if (error || req->newptr == NULL)
> >  	      	return (error);
> >  	   error = linux_set_emul_path(req->td, emul_path);
> > -	   for (brandinfo = &linux_brandlist[0]; *brandinfo != NULL;
> > -		 ++brandinfo)
> > -	      	if (elf32_insert_brand_entry(*brandinfo) < 0)
> > -		   error = EINVAL;	   
> > +	   {
> > +	        static Elf32_Brandinfo linux_brand = {
> > +		   ELFOSABI_LINUX,
> > +		   EM_386,
> > +		   "Linux",
> > +		   emul_path,
> > +		   "/lib/ld-linux.so.1",
> > +		   &elf_linux_sysvec,
> > +		   NULL,
> > +		   BI_CAN_EXEC_DYN,
> > +		};
> > +	        static Elf32_Brandinfo linux_glibc2brand = {
> > +		   ELFOSABI_LINUX,
> > +		   EM_386,
> > +		   "Linux",
> > +		   emul_path,
> > +		   "/lib/ld-linux.so.2",
> > +		   &elf_linux_sysvec,
> > +		   NULL,
> > +		   BI_CAN_EXEC_DYN,
> > +		};
> > +		
> > +	        Elf32_Brandinfo *local_linux_brandlist[] = {
> > +		   &linux_brand,
> > +		   &linux_glibc2brand,
> > +		   NULL
> > +		};
> > +
> > +   	   	for (brandinfo = &local_linux_brandlist[0]; *brandinfo != NULL;
> > +		 	++brandinfo)
> > +	      		if (elf32_insert_brand_entry(*brandinfo) < 0)
> > +		   		error = EINVAL;	   
> > +	   }
> >  	   return (error);
> >  }
> 
> I don't think this is going to work because the brand lists aren't
> per-prison, they are one shared list.  That is, once you create a
> jail and try to change the path, the insert's will add new entries
> to the end of the list, but an earlier entry for another jail
> might handle the binary instead.  Also, elf32_insert_brand_entry()

hm... so there's no (easy) way to do it per-prison, right?

> saves the pointer you pass to it, and your pointers are for variables
> that are on the stack which will become garbage when this function
> returns.

the variable is declared static so it should work