From: Willem de Bruijn <will...@google.com>
bpf_skb_change_proto and bpf_skb_adjust_room change skb header length.
For GSO packets they adjust gso_size to maintain the same MTU.
The gso size can only be safely adjusted on bytestream protocols.
Commit d02f51cbcf12 ("bpf: fix bpf_skb_adjust_net/bpf_skb_proto_xlat
to deal with gso sctp skbs") excluded SKB_GSO_SCTP.
Since then type SKB_GSO_UDP_L4 has been added, whose contents are one
gso_size unit per datagram. Also exclude these.
Move from a blacklist to a whitelist check to future proof against
additional such new GSO types, e.g., for fraglist based GRO.
Fixes: bec1f6f69736 ("udp: generate gso with UDP_SEGMENT")
Signed-off-by: Willem de Bruijn <will...@google.com>
---
include/linux/skbuff.h | 6 ++++++
net/core/filter.c | 12 ++++--------
2 files changed, 10 insertions(+), 8 deletions(-)
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 95d25b010a257..5a7a8b93a5abf 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -4212,6 +4212,12 @@ static inline bool skb_is_gso_sctp(const struct sk_buff
*skb)
return skb_shinfo(skb)->gso_type & SKB_GSO_SCTP;
}
+static inline bool skb_is_gso_tcp(const struct sk_buff *skb)
+{
+ return skb_is_gso(skb) &&
+ skb_shinfo(skb)->gso_type & (SKB_GSO_TCPV4 | SKB_GSO_TCPV6);
+}
+
static inline void skb_gso_reset(struct sk_buff *skb)
{
skb_shinfo(skb)->gso_size = 0;
diff --git a/net/core/filter.c b/net/core/filter.c
index 7a54dc11ac2d3..f7d0004fc1609 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -2789,8 +2789,7 @@ static int bpf_skb_proto_4_to_6(struct sk_buff *skb)
u32 off = skb_mac_header_len(skb);
int ret;
- /* SCTP uses GSO_BY_FRAGS, thus cannot adjust it. */
- if (skb_is_gso(skb) && unlikely(skb_is_gso_sctp(skb)))
+ if (!skb_is_gso_tcp(skb))
return -ENOTSUPP;
ret = skb_cow(skb, len_diff);
@@ -2831,8 +2830,7 @@ static int bpf_skb_proto_6_to_4(struct sk_buff *skb)
u32 off = skb_mac_header_len(skb);
int ret;
- /* SCTP uses GSO_BY_FRAGS, thus cannot adjust it. */
- if (skb_is_gso(skb) && unlikely(skb_is_gso_sctp(skb)))
+ if (!skb_is_gso_tcp(skb))
return -ENOTSUPP;
ret = skb_unclone(skb, GFP_ATOMIC);
@@ -2957,8 +2955,7 @@ static int bpf_skb_net_grow(struct sk_buff *skb, u32
len_diff)
u32 off = skb_mac_header_len(skb) + bpf_skb_net_base_len(skb);
int ret;
- /* SCTP uses GSO_BY_FRAGS, thus cannot adjust it. */
- if (skb_is_gso(skb) && unlikely(skb_is_gso_sctp(skb)))
+ if (!skb_is_gso_tcp(skb))
return -ENOTSUPP;
ret = skb_cow(skb, len_diff);
@@ -2987,8 +2984,7 @@ static int bpf_skb_net_shrink(struct sk_buff *skb, u32
len_diff)
u32 off = skb_mac_header_len(skb) + bpf_skb_net_base_len(skb);
int ret;
- /* SCTP uses GSO_BY_FRAGS, thus cannot adjust it. */
- if (skb_is_gso(skb) && unlikely(skb_is_gso_sctp(skb)))
+ if (!skb_is_gso_tcp(skb))
return -ENOTSUPP;
ret = skb_unclone(skb, GFP_ATOMIC);
--
2.20.1.611.gfbb209baf1-goog
