| From ebe48d368e97d007bfeb76fcb065d6cfc4c96645 Mon Sep 17 00:00:00 2001 |
| From: Steffen Klassert <steffen.klassert@secunet.com> |
| Date: Mon, 7 Mar 2022 13:11:39 +0100 |
| Subject: esp: Fix possible buffer overflow in ESP transformation |
| |
| From: Steffen Klassert <steffen.klassert@secunet.com> |
| |
| commit ebe48d368e97d007bfeb76fcb065d6cfc4c96645 upstream. |
| |
| 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. |
| |
| 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> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| --- |
| include/net/esp.h | 2 ++ |
| include/net/sock.h | 3 +++ |
| net/core/sock.c | 3 --- |
| net/ipv4/esp4.c | 5 +++++ |
| net/ipv6/esp6.c | 5 +++++ |
| 5 files changed, 15 insertions(+), 3 deletions(-) |
| |
| --- 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) |
| --- a/include/net/sock.h |
| +++ b/include/net/sock.h |
| @@ -2438,4 +2438,7 @@ extern int sysctl_optmem_max; |
| 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) |
| + |
| #endif /* _SOCK_H */ |
| --- a/net/core/sock.c |
| +++ b/net/core/sock.c |
| @@ -2193,9 +2193,6 @@ static void sk_leave_memory_pressure(str |
| } |
| } |
| |
| -/* On 32bit arches, an skb frag is limited to 2^15 */ |
| -#define SKB_FRAG_PAGE_ORDER get_order(32768) |
| - |
| /** |
| * skb_page_frag_refill - check that a page_frag contains enough room |
| * @sz: minimum size of the fragment we want to get |
| --- a/net/ipv4/esp4.c |
| +++ b/net/ipv4/esp4.c |
| @@ -257,6 +257,7 @@ int esp_output_head(struct xfrm_state *x |
| 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) { |
| @@ -266,6 +267,10 @@ int esp_output_head(struct xfrm_state *x |
| 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; |
| --- a/net/ipv6/esp6.c |
| +++ b/net/ipv6/esp6.c |
| @@ -223,6 +223,11 @@ int esp6_output_head(struct xfrm_state * |
| 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)) { |
