Re: [PATCH 2/2] exec: increase BINPRM_BUF_SIZE to 256

Re: [PATCH 2/2] exec: increase BINPRM_BUF_SIZE to 256

[Alan Cox]

On Mon, 12 Nov 2018 17:09:56 +0100
Oleg Nesterov <oleg@redhat.com> wrote:

> Large enterprise clients often times run applications out of networked
> file systems where the IT mandated layout of project volumes can end up
> leading to paths that are longer than 128 characters. Bumping this up to
> the next order of two solves this problem in all but the most egregious
> case while still fitting into a 512b slab.

You also need to update the execve manual page as it explicitly documents
the 128 byte limit.

Alan

Re: [PATCH 2/2] exec: increase BINPRM_BUF_SIZE to 256

[Oleg Nesterov]

On 11/16, Alan Cox wrote:
>
> On Mon, 12 Nov 2018 17:09:56 +0100
> Oleg Nesterov <oleg@redhat.com> wrote:
>
> > Large enterprise clients often times run applications out of networked
> > file systems where the IT mandated layout of project volumes can end up
> > leading to paths that are longer than 128 characters. Bumping this up to
> > the next order of two solves this problem in all but the most egregious
> > case while still fitting into a 512b slab.
>
> You also need to update the execve manual page as it explicitly documents
> the 128 byte limit.

Thanks, Eugene sent the patch:

	[PATCH] execve.2: document an effect of BINPRM_BUF_SIZE increase to 256
	https://marc.info/?l=linux-man&m=154281645706657

Oleg.

Re: [PATCH] execve.2: document an effect of BINPRM_BUF_SIZE increase to 256

[Eugene Syromiatnikov]

On Thu, Nov 22, 2018 at 04:59:24PM +0100, Michael Kerrisk (man-pages) wrote:
> Hi Eugene,
> 
> On Wed, 21 Nov 2018 at 17:07, Eugene Syromiatnikov <esyr@redhat.com> wrote:
> >
> > Increase of BINPRM_BUF_SIZE to 256 increases the limit on the possible
> > interpreter line length for scripts to 255.
> 
> I don't see this in the kernel source tree? Could you point me at the
> right source file / git commit?

Sorry, it's a corresponding man page update for a proposed kernel
change[1][2], and I failed to Cc: all the related parties properly.

[1] https://lkml.org/lkml/2018/11/12/2330
[2] https://lkml.org/lkml/2018/11/12/2328

> Thanks,
> 
> Michael
> 
> > Signed-off-by: Eugene Syromiatnikov <esyr@redhat.com>
> > ---
> >  man2/execve.2 | 5 +++--
> >  1 file changed, 3 insertions(+), 2 deletions(-)
> >
> > diff --git a/man2/execve.2 b/man2/execve.2
> > index d2bb861..f4e37d6 100644
> > --- a/man2/execve.2
> > +++ b/man2/execve.2
> > @@ -633,8 +633,9 @@ prototype:
> >  .in
> >  .\"
> >  .SS Interpreter scripts
> > -A maximum line length of 127 characters is allowed for the first line in
> > -an interpreter script.
> > +Before Linux 4.20, a maximum line length of 127 characters was allowed
> > +for the first line in an interpreter script.
> > +In Linux 4.20 onwards, this limit was increased up to 255 characters.
> >  .PP
> >  The semantics of the
> >  .I optional-arg
> > --
> > 2.1.4
> >
> 
> 
> -- 
> Michael Kerrisk
> Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
> Linux/UNIX System Programming Training: http://man7.org/training/