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| author | David S. Miller <davem@davemloft.net> | 2021-03-25 15:31:22 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2021-03-25 15:31:22 -0700 |
| commit | efd13b71a3fa31413f8d15342e01d44b60b0a432 (patch) | |
| tree | 2ed1b299e25538c5a60485a1047507b49d3e0ecf /include/uapi/linux/bpf.h | |
| parent | 84c7f6c33f42a12eb036ebf0f0e3670799304120 (diff) | |
| parent | 002322402dafd846c424ffa9240a937f49b48c42 (diff) | |
Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include/uapi/linux/bpf.h')
| -rw-r--r-- | include/uapi/linux/bpf.h | 16 |
1 files changed, 11 insertions, 5 deletions
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 2d3036e292a9..008edc1dc8c1 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -4573,7 +4573,7 @@ union bpf_attr { * * long bpf_check_mtu(void *ctx, u32 ifindex, u32 *mtu_len, s32 len_diff, u64 flags) * Description - * Check ctx packet size against exceeding MTU of net device (based + * Check packet size against exceeding MTU of net device (based * on *ifindex*). This helper will likely be used in combination * with helpers that adjust/change the packet size. * @@ -4590,6 +4590,14 @@ union bpf_attr { * against the current net device. This is practical if this isn't * used prior to redirect. * + * On input *mtu_len* must be a valid pointer, else verifier will + * reject BPF program. If the value *mtu_len* is initialized to + * zero then the ctx packet size is use. When value *mtu_len* is + * provided as input this specify the L3 length that the MTU check + * is done against. Remember XDP and TC length operate at L2, but + * this value is L3 as this correlate to MTU and IP-header tot_len + * values which are L3 (similar behavior as bpf_fib_lookup). + * * The Linux kernel route table can configure MTUs on a more * specific per route level, which is not provided by this helper. * For route level MTU checks use the **bpf_fib_lookup**\ () @@ -4614,11 +4622,9 @@ union bpf_attr { * * On return *mtu_len* pointer contains the MTU value of the net * device. Remember the net device configured MTU is the L3 size, - * which is returned here and XDP and TX length operate at L2. + * which is returned here and XDP and TC length operate at L2. * Helper take this into account for you, but remember when using - * MTU value in your BPF-code. On input *mtu_len* must be a valid - * pointer and be initialized (to zero), else verifier will reject - * BPF program. + * MTU value in your BPF-code. * * Return * * 0 on success, and populate MTU value in *mtu_len* pointer. |