Messages in this thread Patch in this message | | | Date | Fri, 12 Sep 2008 13:52:26 +0200 | From | Adam Tkac <> | Subject | Re: [PATCH 2.6.27-rc5] Allow set RLIMIT_NOFILE to RLIM_INFINITY |
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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) | |