Patch Related with Fork Bombing Attack

From: Anand Jahagirdar
Date: Fri Jul 13 2007 - 08:39:25 EST


Hello All
I have searched for Maintainers List to get the correct
Maintainer for my patch. But i am not getting exact maintainer to
which i should forward my patch. Will any body please tell me,to which
maintainer i should forward my patch for its inclusion?

Summery of the Patch:

This patch Warns the administrator about the fork bombing attack
(whenever any user is crossing its process limit). I have used
printk_ratelimit function in this patch. This function helps to
prevent flooding of syslog and prints message as per the values set by
root user in following files:-

1) /proc/sys/kernel/printk_ratelimit:- This file contains value for,
how many times message should be printed in syslog.

2) /proc/sys/kernel/printk_ratelimit_burst: - This file contains value
for, after how much time message should be repeated.

This patch is really helpful for administrator/root user from security
point of view. They can take action against attacker by looking at
syslog messages related with fork bombing attack.

Added comments will definitely help developers.

Signed-Off-by: Anand Jahagirdar <anandjigar@xxxxxxxxx> Index: root/Desktop/a1/linux-2.6.17.tar.bz2_FILES/linux-2.6.17/kernel/fork.c
===================================================================
--- root.orig/Desktop/a1/linux-2.6.17.tar.bz2_FILES/linux-2.6.17/kernel/fork.c 2007-06-26 20:40:06.000000000 +0530
+++ root/Desktop/a1/linux-2.6.17.tar.bz2_FILES/linux-2.6.17/kernel/fork.c 2007-06-26 20:41:41.000000000 +0530
@@ -957,12 +957,19 @@

retval = -EAGAIN;

-
+ /*
+ * following code does not allow Non Root User to cross its process
+ * limit and it alerts administrator about user crossing the process limit.
+ */
+
if (atomic_read(&p->user->processes) >= p->signal->rlim[RLIMIT_NPROC].rlim_cur)
if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_RESOURCE) &&
- p->user != &root_user)
+ p->user != &root_user) {
+ if (printk_ratelimit())
+ printk(KERN_WARNING "User with uid %u is crossing the process limit\n",p->user->uid);
+
goto bad_fork_free;
-
+ }

atomic_inc(&p->user->__count);
atomic_inc(&p->user->processes);