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Message-Id: <42957681548090694@sas1-adb97d30497b.qloud-c.yandex.net>
Date: Mon, 21 Jan 2019 20:11:34 +0300
From: Nazarov Sergey <s-nazarov@...dex.ru>
To: Paul Moore <paul@...l-moore.com>
Cc: "linux-security-module@...r.kernel.org"
<linux-security-module@...r.kernel.org>,
"selinux@...r.kernel.org" <selinux@...r.kernel.org>,
"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
Casey Schaufler <casey@...aufler-ca.com>
Subject: Re: Kernel memory corruption in CIPSO labeled TCP packets processing.
18.01.2019, 20:17, "Paul Moore" <paul@...l-moore.com>:
> Yes, this is extra overhead, but it is in an error path so I'm not
> overly concerned about the performance impact on the given connection.
>
> I will admit that it isn't an ideal solution from a LSM/NetLabel
> perspective, but historically the netdev folks have not been overly
> receptive to changes which negatively impact the core network stack
> regardless of how important it may be for the LSMs. If we could
> modify icmp_send() so that it works regardless of the caller's
> location in the stack, that would be great, I'm just not sure it would
> be deemed acceptable. I suggested the approach I did because I think
> that has the best chance of getting merged.
>
> Regardless, I would encourage you to put together a patch and post it
> for review, I think that's the best way to get a response. If you
> aren't able, or aren't comfortable, submitting a patch please let me
> know.
> --
> paul moore
> www.paul-moore.com
May be something like that?
[PATCH 1/2] Add IP options parameter to icmp_send
---
include/net/icmp.h | 9 ++++++++-
net/ipv4/icmp.c | 7 ++++---
2 files changed, 12 insertions(+), 4 deletions(-)
diff --git a/include/net/icmp.h b/include/net/icmp.h
index 6ac3a5b..e0f709d 100644
--- a/include/net/icmp.h
+++ b/include/net/icmp.h
@@ -22,6 +22,7 @@
#include <net/inet_sock.h>
#include <net/snmp.h>
+#include <net/ip.h>
struct icmp_err {
int errno;
@@ -39,7 +40,13 @@ struct icmp_err {
struct sk_buff;
struct net;
-void icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info);
+void __icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info,
+ const struct ip_options *opt);
+static inline void icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info)
+{
+ __icmp_send(skb_in, type, code, info, &IPCB(skb_in)->opt);
+}
+
int icmp_rcv(struct sk_buff *skb);
int icmp_err(struct sk_buff *skb, u32 info);
int icmp_init(void);
diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c
index 065997f..3f24414 100644
--- a/net/ipv4/icmp.c
+++ b/net/ipv4/icmp.c
@@ -570,7 +570,8 @@ static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb)
* MUST reply to only the first fragment.
*/
-void icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info)
+void __icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info,
+ const struct ip_options *opt)
{
struct iphdr *iph;
int room;
@@ -691,7 +692,7 @@ void icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info)
iph->tos;
mark = IP4_REPLY_MARK(net, skb_in->mark);
- if (ip_options_echo(net, &icmp_param.replyopts.opt.opt, skb_in))
+ if (__ip_options_echo(net, &icmp_param.replyopts.opt.opt, skb_in, opt))
goto out_unlock;
@@ -742,7 +743,7 @@ void icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info)
local_bh_enable();
out:;
}
-EXPORT_SYMBOL(icmp_send);
+EXPORT_SYMBOL(__icmp_send);
static void icmp_socket_deliver(struct sk_buff *skb, u32 info)
---
[PATCH 2/2] Extract IP options in cipso_v4_error
---
include/net/ip.h | 2 ++
net/ipv4/cipso_ipv4.c | 11 +++++++++--
net/ipv4/ip_options.c | 22 +++++++++++++++++-----
3 files changed, 28 insertions(+), 7 deletions(-)
diff --git a/include/net/ip.h b/include/net/ip.h
index 8866bfc..f0e8d06 100644
--- a/include/net/ip.h
+++ b/include/net/ip.h
@@ -667,6 +667,8 @@ static inline int ip_options_echo(struct net *net, struct ip_options *dopt,
}
void ip_options_fragment(struct sk_buff *skb);
+int __ip_options_compile(struct net *net, struct ip_options *opt,
+ struct sk_buff *skb, __be32 *info);
int ip_options_compile(struct net *net, struct ip_options *opt,
struct sk_buff *skb);
int ip_options_get(struct net *net, struct ip_options_rcu **optp,
diff --git a/net/ipv4/cipso_ipv4.c b/net/ipv4/cipso_ipv4.c
index 777fa3b..86599e9 100644
--- a/net/ipv4/cipso_ipv4.c
+++ b/net/ipv4/cipso_ipv4.c
@@ -1735,13 +1735,20 @@ int cipso_v4_validate(const struct sk_buff *skb, unsigned char **option)
*/
void cipso_v4_error(struct sk_buff *skb, int error, u32 gateway)
{
+ unsigned char optbuf[sizeof(struct ip_options) + 40];
+ struct ip_options *opt = (struct ip_options *)optbuf;
+
if (ip_hdr(skb)->protocol == IPPROTO_ICMP || error != -EACCES)
return;
+ opt->optlen = ip_hdr(skb)->ihl*4 - sizeof(struct iphdr);
+ if (__ip_options_compile(dev_net(skb->dev), opt, skb, NULL))
+ return;
+
if (gateway)
- icmp_send(skb, ICMP_DEST_UNREACH, ICMP_NET_ANO, 0);
+ __icmp_send(skb, ICMP_DEST_UNREACH, ICMP_NET_ANO, 0, opt);
else
- icmp_send(skb, ICMP_DEST_UNREACH, ICMP_HOST_ANO, 0);
+ __icmp_send(skb, ICMP_DEST_UNREACH, ICMP_HOST_ANO, 0, opt);
}
/**
diff --git a/net/ipv4/ip_options.c b/net/ipv4/ip_options.c
index ed194d4..32a3504 100644
--- a/net/ipv4/ip_options.c
+++ b/net/ipv4/ip_options.c
@@ -251,8 +251,9 @@ static void spec_dst_fill(__be32 *spec_dst, struct sk_buff *skb)
* If opt == NULL, then skb->data should point to IP header.
*/
-int ip_options_compile(struct net *net,
- struct ip_options *opt, struct sk_buff *skb)
+int __ip_options_compile(struct net *net,
+ struct ip_options *opt, struct sk_buff *skb,
+ __be32 *info)
{
__be32 spec_dst = htonl(INADDR_ANY);
unsigned char *pp_ptr = NULL;
@@ -468,11 +469,22 @@ int ip_options_compile(struct net *net,
return 0;
error:
- if (skb) {
- icmp_send(skb, ICMP_PARAMETERPROB, 0, htonl((pp_ptr-iph)<<24));
- }
+ if (info)
+ *info = htonl((pp_ptr-iph)<<24);
return -EINVAL;
}
+
+int ip_options_compile(struct net *net,
+ struct ip_options *opt, struct sk_buff *skb)
+{
+ int ret;
+ __be32 info;
+
+ ret = __ip_options_compile(net, opt, skb, &info);
+ if (ret != 0 && skb)
+ icmp_send(skb, ICMP_PARAMETERPROB, 0, info);
+ return ret;
+}
EXPORT_SYMBOL(ip_options_compile);
/*
---
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