diff options
| author | John Fastabend <john.fastabend@gmail.com> | 2018-03-18 12:57:20 -0700 |
|---|---|---|
| committer | Daniel Borkmann <daniel@iogearbox.net> | 2018-03-19 21:14:39 +0100 |
| commit | 91843d540a139eb8070bcff8aa10089164436deb (patch) | |
| tree | 9d8907f96f184bd3953bb5a2365a44ed85e0d132 /include | |
| parent | 2a100317c9ebc204a166f16294884fbf9da074ce (diff) | |
| download | linux-91843d540a139eb8070bcff8aa10089164436deb.tar.bz2 | |
bpf: sockmap, add msg_cork_bytes() helper
In the case where we need a specific number of bytes before a
verdict can be assigned, even if the data spans multiple sendmsg
or sendfile calls. The BPF program may use msg_cork_bytes().
The extreme case is a user can call sendmsg repeatedly with
1-byte msg segments. Obviously, this is bad for performance but
is still valid. If the BPF program needs N bytes to validate
a header it can use msg_cork_bytes to specify N bytes and the
BPF program will not be called again until N bytes have been
accumulated. The infrastructure will attempt to coalesce data
if possible so in many cases (most my use cases at least) the
data will be in a single scatterlist element with data pointers
pointing to start/end of the element. However, this is dependent
on available memory so is not guaranteed. So BPF programs must
validate data pointer ranges, but this is the case anyways to
convince the verifier the accesses are valid.
Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Diffstat (limited to 'include')
| -rw-r--r-- | include/uapi/linux/bpf.h | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index a557a2a5d72d..1765cfb16c99 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -792,7 +792,8 @@ union bpf_attr { FN(override_return), \ FN(sock_ops_cb_flags_set), \ FN(msg_redirect_map), \ - FN(msg_apply_bytes), + FN(msg_apply_bytes), \ + FN(msg_cork_bytes), /* integer value in 'imm' field of BPF_CALL instruction selects which helper * function eBPF program intends to call |