When a task is attempting to violate the RLIMIT_NPROC limit we have a
check to see if the task is sufficiently priviledged. The check first
looks at CAP_SYS_ADMIN, then CAP_SYS_RESOURCE, then if the task is
uid=0. A result is that tasks which are allowed by the uid=0 check are
first checked against the security subsystem. This results in the
security subsystem auditting a denial for sys_admin and sys_resource and
then the task passing the uid=0 check. This patch rearrainges the code
to first check uid=0, since if we pass that we shouldn't hit the
security system at all. We then check sys_resource, since it is the
smallest capability which will solve the problem. Lastly we check the
fallback everything cap_sysadmin. We don't want to give this capability
many places since it is so powerful. This will eliminate many of the
false positive/needless denial messages we get when a root task tries to
violate the nproc limit. (note that kthreads count against root, so on
a sufficiently large machine we can actually get past the default limits
before any userspace tasks are launched.)
Signed-off-by: Eric Paris <epa...@redhat.com>
---
kernel/fork.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/fork.c b/kernel/fork.c
index 987b28a..09dbda3 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1199,8 +1199,8 @@ static struct task_struct *copy_process(unsigned long
clone_flags,
retval = -EAGAIN;
if (atomic_read(&p->real_cred->user->processes) >=
task_rlimit(p, RLIMIT_NPROC)) {
- if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_RESOURCE) &&
- p->real_cred->user != INIT_USER)
+ if (p->real_cred->user != INIT_USER &&
+ !capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN))
goto bad_fork_free;
}
current->flags &= ~PF_NPROC_EXCEEDED;
--
1.8.2.1
--
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