lkml.org 
[lkml]   [2008]   [Sep]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
SubjectRe: [PATCH 2.6.27-rc5] Allow set RLIMIT_NOFILE to RLIM_INFINITY
On Fri, Sep 12, 2008 at 01:20:46PM +0200, Andreas Schwab wrote:
> Adam Tkac <vonsch@gmail.com> writes:
>
> > diff -puN kernel/sys.c~rlimit-permit-setting-rlimit_nofile-to-rlim_infinity kernel/sys.c
> > --- a/kernel/sys.c~rlimit-permit-setting-rlimit_nofile-to-rlim_infinity
> > +++ a/kernel/sys.c
> > @@ -1532,8 +1532,14 @@ asmlinkage long sys_setrlimit(unsigned i
> > if ((new_rlim.rlim_max > old_rlim->rlim_max) &&
> > !capable(CAP_SYS_RESOURCE))
> > return -EPERM;
> > - if (resource == RLIMIT_NOFILE && new_rlim.rlim_max > sysctl_nr_open)
> > - return -EPERM;
> > + if (resource == RLIMIT_NOFILE) {
> > + if (new_rlim.rlim_max == RLIM_INFINITY)
> > + new_rlim.rlim_max = sysctl_nr_open;
> > + if (new_rlim.rlim_cur == RLIM_INFINITY)
> > + new_rlim.rlim_cur = sysctl_nr_open;
> > + if (new_rlim.rlim_max > sysctl_nr_open)
> > + return -EPERM;
>
> This makes it possible to set cur > nr_open (when max = INF but nr_open
> < cur < INF). You need to check that cur <= max after adjustment.
>
> Andreas.
>

Right you are. Improved patch is attached, when cur > max && cur !=
INF after adjustment EINVAL is returned. (cur can be also set to max
but it seems like bad solution for me)
--
Adam Tkac

When a process wants to set the limit of open files to RLIM_INFINITY it
gets EPERM even if it has CAP_SYS_RESOURCE capability.

For example, BIND does:

...
#elif defined(NR_OPEN) && defined(__linux__)
/*
* Some Linux kernels don't accept RLIM_INFINIT; the maximum
* possible value is the NR_OPEN defined in linux/fs.h.
*/
if (resource == isc_resource_openfiles && rlim_value == RLIM_INFINITY) {
rl.rlim_cur = rl.rlim_max = NR_OPEN;
unixresult = setrlimit(unixresource, &rl);
if (unixresult == 0)
return (ISC_R_SUCCESS);
}
#elif ...
If we allow setting RLIMIT_NOFILE to RLIM_INFINITY we increase portability
- you don't have to check if OS is linux and then use different schema for
limits.

The spec says "Specifying RLIM_INFINITY as any resource limit value on a
successful call to setrlimit() shall inhibit enforcement of that resource
limit." and we're presently not doing that.

Signed-off-by: Adam Tkac <vonsch@gmail.com>
--- a/kernel/sys.c.openfiles
+++ a/kernel/sys.c
@@ -1469,14 +1469,22 @@ asmlinkage long sys_setrlimit(unsigned i
return -EINVAL;
if (copy_from_user(&new_rlim, rlim, sizeof(*rlim)))
return -EFAULT;
- if (new_rlim.rlim_cur > new_rlim.rlim_max)
- return -EINVAL;
old_rlim = current->signal->rlim + resource;
if ((new_rlim.rlim_max > old_rlim->rlim_max) &&
!capable(CAP_SYS_RESOURCE))
return -EPERM;
- if (resource == RLIMIT_NOFILE && new_rlim.rlim_max > sysctl_nr_open)
- return -EPERM;
+
+ if (resource == RLIMIT_NOFILE) {
+ if (new_rlim.rlim_max == RLIM_INFINITY)
+ new_rlim.rlim_max = sysctl_nr_open;
+ if (new_rlim.rlim_cur == RLIM_INFINITY)
+ new_rlim.rlim_cur = sysctl_nr_open;
+ if (new_rlim.rlim_max > sysctl_nr_open)
+ return -EPERM;
+ }
+
+ if (new_rlim.rlim_cur > new_rlim.rlim_max)
+ return -EINVAL;

retval = security_task_setrlimit(resource, &new_rlim);
if (retval)
\
 
 \ /
  Last update: 2008-09-12 13:55    [from the cache]
©2003-2014 Jasper Spaans. Advertise on this site