diff options
| author | Jesper Dangaard Brouer <brouer@redhat.com> | 2021-03-08 15:59:18 +0100 |
|---|---|---|
| committer | Daniel Borkmann <daniel@iogearbox.net> | 2021-03-08 22:44:33 +0100 |
| commit | e5e35e754c28724d5c619f2ec805fd221f8d59ce (patch) | |
| tree | c39a3c01d112c3b8143d3f70edb864dac6e0dde8 /net/core | |
| parent | e7fb6465d4c8e767e39cbee72464e0060ab3d20c (diff) | |
bpf: BPF-helper for MTU checking add length input
The FIB lookup example[1] show how the IP-header field tot_len
(iph->tot_len) is used as input to perform the MTU check.
This patch extend the BPF-helper bpf_check_mtu() with the same ability
to provide the length as user parameter input, via mtu_len parameter.
This still needs to be done before the bpf_check_mtu() helper API
becomes frozen.
[1] samples/bpf/xdp_fwd_kern.c
Fixes: 34b2021cc616 ("bpf: Add BPF-helper for MTU checking")
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/161521555850.3515614.6533850861569774444.stgit@firesoul
Diffstat (limited to 'net/core')
| -rw-r--r-- | net/core/filter.c | 12 |
1 files changed, 10 insertions, 2 deletions
diff --git a/net/core/filter.c b/net/core/filter.c index adfdad234674..9323d34d34cc 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -5658,7 +5658,7 @@ BPF_CALL_5(bpf_skb_check_mtu, struct sk_buff *, skb, if (unlikely(flags & ~(BPF_MTU_CHK_SEGS))) return -EINVAL; - if (unlikely(flags & BPF_MTU_CHK_SEGS && len_diff)) + if (unlikely(flags & BPF_MTU_CHK_SEGS && (len_diff || *mtu_len))) return -EINVAL; dev = __dev_via_ifindex(dev, ifindex); @@ -5668,7 +5668,11 @@ BPF_CALL_5(bpf_skb_check_mtu, struct sk_buff *, skb, mtu = READ_ONCE(dev->mtu); dev_len = mtu + dev->hard_header_len; - skb_len = skb->len + len_diff; /* minus result pass check */ + + /* If set use *mtu_len as input, L3 as iph->tot_len (like fib_lookup) */ + skb_len = *mtu_len ? *mtu_len + dev->hard_header_len : skb->len; + + skb_len += len_diff; /* minus result pass check */ if (skb_len <= dev_len) { ret = BPF_MTU_CHK_RET_SUCCESS; goto out; @@ -5713,6 +5717,10 @@ BPF_CALL_5(bpf_xdp_check_mtu, struct xdp_buff *, xdp, /* Add L2-header as dev MTU is L3 size */ dev_len = mtu + dev->hard_header_len; + /* Use *mtu_len as input, L3 as iph->tot_len (like fib_lookup) */ + if (*mtu_len) + xdp_len = *mtu_len + dev->hard_header_len; + xdp_len += len_diff; /* minus result pass check */ if (xdp_len > dev_len) ret = BPF_MTU_CHK_RET_FRAG_NEEDED; |