Messages in this thread Patch in this message | | | Date | Thu, 11 Sep 2008 12:22:19 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH 2.6.27-rc5] Allow set RLIMIT_NOFILE to RLIM_INFINITY |
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On Thu, 11 Sep 2008 09:54:38 +0200 Adam Tkac <vonsch@gmail.com> wrote:
> On Wed, Sep 10, 2008 at 02:31:41PM -0700, Andrew Morton wrote: > > On Tue, 9 Sep 2008 09:14:07 +0200 > > Adam Tkac <vonsch@gmail.com> wrote: > > > > > when process wants set limit of open files to RLIM_INFINITY it gets > > > EPERM even if it has CAP_SYS_RESOURCE capability. Attached patch > > > should fix the problem. Please add me to CC of your responses because > > > I'm not member of list. > > > > > > Regards, Adam > > > > > > -- > > > Adam Tkac > > > > > > > > > [linux26-openfiles.patch text/plain (634B)] > > > --- a/kernel/sys.c > > > +++ b/kernel/sys.c > > > @@ -1458,8 +1458,14 @@ 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; > > > + } > > > > The kernel has had this behaviour for a long time. 2.6.13 had: > > > > if ((new_rlim.rlim_max > old_rlim->rlim_max) && > > !capable(CAP_SYS_RESOURCE)) > > return -EPERM; > > if (resource == RLIMIT_NOFILE && new_rlim.rlim_max > NR_OPEN) > > return -EPERM; > > > > I don't immediately see a problem with your change, but what makes you > > believe that it is needed? Is there some standard which we're > > violating? Is there some operational situation in which the current > > behaviour is causing a problem? > > > > Thanks. > > Well, this change is not _absolutely_ needed because everyone who wants > unlimited file descriptors he could set it to NR_OPEN. Look on > example (from BIND): > > ... > #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 ... > > I think that when you allow set RLIMIT_NOFILE to RLIM_INFINITY you > increase portability - you don't have to check if OS is linux and then > use different schema for limits. >
OK.
I updated the changelog as below.
Please send a Signed-off-by: for thsi change, as per section 12 of Documentation/SubmittingPatches.
Thanks.
From: Adam Tkac <vonsch@gmail.com>
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.
Cc: Michael Kerrisk <mtk.manpages@googlemail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> ---
kernel/sys.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-)
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; + } retval = security_task_setrlimit(resource, &new_rlim); if (retval) _
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