esp: Fix possible buffer overflow in ESP transformation
[ Upstream commit ebe48d368e97d007bfeb76fcb065d6cfc4c96645 ]
The maximum message size that can be send is bigger than
the maximum site that skb_page_frag_refill can allocate.
So it is possible to write beyond the allocated buffer.
Fix this by doing a fallback to COW in that case.
v2:
Avoid get get_order() costs as suggested by Linus Torvalds.
For having the patch build on v5.4, following changes are done:
- `SKB_FRAG_PAGE_ORDER` declaration is moved from net/core/sock.c to include/net/sock.c.
- Remove changes introduced due to `xfrm: add support for UDPv6 encapsulation of ESP` in esp6_output_head
BUG=b/225430860
TEST=presubmit
RELEASE_NOTE=Fixed possible buffer overflow in ESP transformation.
cos-patch: bug
Fixes: cac2661c53f3 ("esp4: Avoid skb_cow_data whenever possible")
Fixes: 03e2a30f6a27 ("esp6: Avoid skb_cow_data whenever possible")
Reported-by: valis <sec@valis.email>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Vaibhav Rustagi <vaibhavrustagi@google.com>
Change-Id: Ibba7d1063e1e78fe8cecb2d0ae1e94a586101a93
Reviewed-on: https://cos-review.googlesource.com/c/third_party/kernel/+/31081
Tested-by: Cusky Presubmit Bot <presubmit@cos-infra-prod.iam.gserviceaccount.com>
Main-Branch-Verified: Cusky Presubmit Bot <presubmit@cos-infra-prod.iam.gserviceaccount.com>
Reviewed-by: Oleksandr Tymoshenko <ovt@google.com>
diff --git a/include/net/esp.h b/include/net/esp.h
index 117652e..465e388 100644
--- a/include/net/esp.h
+++ b/include/net/esp.h
@@ -4,6 +4,8 @@
#include <linux/skbuff.h>
+#define ESP_SKB_FRAG_MAXSIZE (PAGE_SIZE << SKB_FRAG_PAGE_ORDER)
+
struct ip_esp_hdr;
static inline struct ip_esp_hdr *ip_esp_hdr(const struct sk_buff *skb)
diff --git a/include/net/sock.h b/include/net/sock.h
index fed8706..b5b3c6b 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -2611,6 +2611,9 @@
extern __u32 sysctl_wmem_default;
extern __u32 sysctl_rmem_default;
+
+/* On 32bit arches, an skb frag is limited to 2^15 */
+#define SKB_FRAG_PAGE_ORDER get_order(32768)
DECLARE_STATIC_KEY_FALSE(net_high_order_alloc_disable_key);
static inline int sk_get_wmem0(const struct sock *sk, const struct proto *proto)
diff --git a/net/core/sock.c b/net/core/sock.c
index bf4f9d5..a4ee174 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -2367,8 +2367,6 @@
}
}
-/* On 32bit arches, an skb frag is limited to 2^15 */
-#define SKB_FRAG_PAGE_ORDER get_order(32768)
DEFINE_STATIC_KEY_FALSE(net_high_order_alloc_disable_key);
/**
diff --git a/net/ipv4/esp4.c b/net/ipv4/esp4.c
index 86c836f..94e1779 100644
--- a/net/ipv4/esp4.c
+++ b/net/ipv4/esp4.c
@@ -277,6 +277,7 @@
struct page *page;
struct sk_buff *trailer;
int tailen = esp->tailen;
+ unsigned int allocsz;
/* this is non-NULL only with UDP Encapsulation */
if (x->encap) {
@@ -286,6 +287,10 @@
return err;
}
+ allocsz = ALIGN(skb->data_len + tailen, L1_CACHE_BYTES);
+ if (allocsz > ESP_SKB_FRAG_MAXSIZE)
+ goto cow;
+
if (!skb_cloned(skb)) {
if (tailen <= skb_tailroom(skb)) {
nfrags = 1;
diff --git a/net/ipv6/esp6.c b/net/ipv6/esp6.c
index 12570a7..06a172a 100644
--- a/net/ipv6/esp6.c
+++ b/net/ipv6/esp6.c
@@ -230,6 +230,11 @@
struct page *page;
struct sk_buff *trailer;
int tailen = esp->tailen;
+ unsigned int allocsz;
+
+ allocsz = ALIGN(skb->data_len + tailen, L1_CACHE_BYTES);
+ if (allocsz > ESP_SKB_FRAG_MAXSIZE)
+ goto cow;
if (!skb_cloned(skb)) {
if (tailen <= skb_tailroom(skb)) {
