Since cipso_v4_error might be called from different network stack layers, we
can't safely use icmp_send there.
icmp_send copies IP options with ip_option_echo, which uses IPCB to take access
to IP header compiled data.
But after commit 971f10ec ("tcp: better TCP_SKB_CB layout to reduce cache line
misses"), IPCB can't be used
above IP layer.
This patch fixes the problem by creating in cipso_v4_error a local copy of
compiled IP options and using it with
introduced __icmp_send function. This looks some overloaded, but in quite rare
error conditions only.
The original discussion is here:
https://lore.kernel.org/linux-security-module/16659801547571...@sas1-890ba5c2334a.qloud-c.yandex.net/
Signed-off-by: Sergey Nazarov <s-naza...@yandex.ru>
---
include/net/icmp.h | 9 ++++++++-
net/ipv4/cipso_ipv4.c | 18 ++++++++++++++++--
net/ipv4/icmp.c | 7 ++++---
3 files changed, 28 insertions(+), 6 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/cipso_ipv4.c b/net/ipv4/cipso_ipv4.c
index 777fa3b..234d12e 100644
--- a/net/ipv4/cipso_ipv4.c
+++ b/net/ipv4/cipso_ipv4.c
@@ -1735,13 +1735,27 @@ 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;
+ /*
+ * We might be called above the IP layer,
+ * so we can not use icmp_send and IPCB here.
+ */
+
+ memset(opt, 0, sizeof(struct ip_options));
+ opt->optlen = ip_hdr(skb)->ihl*4 - sizeof(struct iphdr);
+ memcpy(opt->__data, (unsigned char *)&(ip_hdr(skb)[1]), opt->optlen);
+ if (ip_options_compile(dev_net(skb->dev), opt, 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/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)
--
