netdev - [PATCH for 2.6.33] conntrack: restrict runtime hashsize modifications

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Date:	Wed, 3 Feb 2010 22:39:29 +0200
From:	Alexey Dobriyan <adobriyan@...il.com>
To:	davem@...emloft.net, kaber@...sh.net
Cc:	jonathan@...masters.org, eric.dumazet@...il.com,
	netdev@...r.kernel.org, netfilter-devel@...r.kernel.org
Subject: [PATCH for 2.6.33] conntrack: restrict runtime hashsize
 modifications

Jon Masters correctly points out that conntrack hash sizes
(nf_conntrack_htable_size) are global (not per-netns) and
modifiable at runtime via /sys/module/nf_conntrack/hashsize .

Steps to reproduce:
	clone(CLONE_NEWNET)
	[grow /sys/module/nf_conntrack/hashsize]
	exit()

At netns exit we are going to scan random memory for conntracks to be killed.

Apparently there is a code which deals with hashtable resize for
init_net (and it was there befode netns conntrack code), so prohibit
hashsize modification if there is more than one netns exists.

To change hashtable sizes, you need to reload module.

Expectation hashtable size was simply glued to a variable with no code
to rehash expectations, so it was a bug to allow writing to it.
Make "expect_hashsize" readonly.

This is temporarily until we figure out what to do.

Signed-off-by: Alexey Dobriyan <adobriyan@...il.com>
Cc: stable@...nel.org
---

 net/netfilter/nf_conntrack_core.c   |   15 +++++++++++++++
 net/netfilter/nf_conntrack_expect.c |    2 +-
 2 files changed, 16 insertions(+), 1 deletion(-)

--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -21,6 +21,7 @@
 #include <linux/stddef.h>
 #include <linux/slab.h>
 #include <linux/random.h>
+#include <linux/rtnetlink.h>
 #include <linux/jhash.h>
 #include <linux/err.h>
 #include <linux/percpu.h>
@@ -1198,6 +1199,20 @@ int nf_conntrack_set_hashsize(const char *val, struct kernel_param *kp)
 	if (!nf_conntrack_htable_size)
 		return param_set_uint(val, kp);
 
+	{
+		struct net *net;
+		unsigned int nr;
+
+		nr = 0;
+		rtnl_lock();
+		for_each_net(net)
+			nr++;
+		rtnl_unlock();
+		/* init_net always exists */
+		if (nr != 1)
+			return -EINVAL;
+	}
+
 	hashsize = simple_strtoul(val, NULL, 0);
 	if (!hashsize)
 		return -EINVAL;
--- a/net/netfilter/nf_conntrack_expect.c
+++ b/net/netfilter/nf_conntrack_expect.c
@@ -569,7 +569,7 @@ static void exp_proc_remove(struct net *net)
 #endif /* CONFIG_PROC_FS */
 }
 
-module_param_named(expect_hashsize, nf_ct_expect_hsize, uint, 0600);
+module_param_named(expect_hashsize, nf_ct_expect_hsize, uint, 0400);
 
 int nf_conntrack_expect_init(struct net *net)
 {
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html