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Subject[PATCH 2.6.27-rc5] Allow set RLIMIT_NOFILE to RLIM_INFINITY
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: Adam Tkac <vonsch@gmail.com>
Tested-by: Adam Tkac <vonsch@gmail.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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