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Code Issues Releases Wiki Activity

Revert "bpf: Check for BPF_F_ADJ_ROOM_FIXED_GSO when bpf_skb_change_proto"

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This reverts commit fa7b83bf3b.

See the followup commit for the reasoning why I believe the appropriate
approach is to simply make this change without a flag, but it can basically
be summarized as using this helper without the flag is bug-prone or outright
buggy, and thus the default should be this new behaviour.

As this commit has only made it into net-next/master, but not into
any real release, such a backwards incompatible change is still ok.

Signed-off-by: Maciej Żenczykowski <maze@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Cc: Dongseok Yi <dseok.yi@samsung.com>
Cc: Willem de Bruijn <willemb@google.com>
Link: https://lore.kernel.org/bpf/20210617000953.2787453-1-zenczykowski@gmail.com
This commit is contained in:
Maciej Żenczykowski 2021-06-16 17:09:50 -07:00 committed by Daniel Borkmann
parent 647d446d66
commit ba47396e1c
1 changed files with 9 additions and 13 deletions
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22
net/core/filter.c
View file

@ -3235,7 +3235,7 @@ static int bpf_skb_net_hdr_pop(struct sk_buff *skb, u32 off, u32 len)
return ret;
}
static int bpf_skb_proto_4_to_6(struct sk_buff *skb, u64 flags)
static int bpf_skb_proto_4_to_6(struct sk_buff *skb)
{
const u32 len_diff = sizeof(struct ipv6hdr) - sizeof(struct iphdr);
u32 off = skb_mac_header_len(skb);
@ -3264,9 +3264,7 @@ static int bpf_skb_proto_4_to_6(struct sk_buff *skb, u64 flags)
}
/* Due to IPv6 header, MSS needs to be downgraded. */
if (!(flags & BPF_F_ADJ_ROOM_FIXED_GSO))
skb_decrease_gso_size(shinfo, len_diff);
skb_decrease_gso_size(shinfo, len_diff);
/* Header must be checked, and gso_segs recomputed. */
shinfo->gso_type |= SKB_GSO_DODGY;
shinfo->gso_segs = 0;
@ -3278,7 +3276,7 @@ static int bpf_skb_proto_4_to_6(struct sk_buff *skb, u64 flags)
return 0;
}
static int bpf_skb_proto_6_to_4(struct sk_buff *skb, u64 flags)
static int bpf_skb_proto_6_to_4(struct sk_buff *skb)
{
const u32 len_diff = sizeof(struct ipv6hdr) - sizeof(struct iphdr);
u32 off = skb_mac_header_len(skb);
@ -3307,9 +3305,7 @@ static int bpf_skb_proto_6_to_4(struct sk_buff *skb, u64 flags)
}
/* Due to IPv4 header, MSS can be upgraded. */
if (!(flags & BPF_F_ADJ_ROOM_FIXED_GSO))
skb_increase_gso_size(shinfo, len_diff);
skb_increase_gso_size(shinfo, len_diff);
/* Header must be checked, and gso_segs recomputed. */
shinfo->gso_type |= SKB_GSO_DODGY;
shinfo->gso_segs = 0;
@ -3321,17 +3317,17 @@ static int bpf_skb_proto_6_to_4(struct sk_buff *skb, u64 flags)
return 0;
}
static int bpf_skb_proto_xlat(struct sk_buff *skb, __be16 to_proto, u64 flags)
static int bpf_skb_proto_xlat(struct sk_buff *skb, __be16 to_proto)
{
__be16 from_proto = skb->protocol;
if (from_proto == htons(ETH_P_IP) &&
to_proto == htons(ETH_P_IPV6))
return bpf_skb_proto_4_to_6(skb, flags);
return bpf_skb_proto_4_to_6(skb);
if (from_proto == htons(ETH_P_IPV6) &&
to_proto == htons(ETH_P_IP))
return bpf_skb_proto_6_to_4(skb, flags);
return bpf_skb_proto_6_to_4(skb);
return -ENOTSUPP;
}
@ -3341,7 +3337,7 @@ BPF_CALL_3(bpf_skb_change_proto, struct sk_buff *, skb, __be16, proto,
{
int ret;
if (unlikely(flags & ~(BPF_F_ADJ_ROOM_FIXED_GSO)))
if (unlikely(flags))
return -EINVAL;
/* General idea is that this helper does the basic groundwork
@ -3361,7 +3357,7 @@ BPF_CALL_3(bpf_skb_change_proto, struct sk_buff *, skb, __be16, proto,
* that. For offloads, we mark packet as dodgy, so that headers
* need to be verified first.
*/
ret = bpf_skb_proto_xlat(skb, proto, flags);
ret = bpf_skb_proto_xlat(skb, proto);
bpf_compute_data_pointers(skb);
return ret;
}