diff options
| author | Petar Penkov <ppenkov@google.com> | 2019-07-29 09:59:15 -0700 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2019-07-30 21:03:05 -0700 |
| commit | 70d66244317e958092e9c971b08dd5b7fd29d9cb (patch) | |
| tree | ce2f9693389e7084cdf245f1a39e3787dcfccdb2 /include/uapi | |
| parent | 9349d600fb6a1ca0aaeb515523e1bb5409483d76 (diff) | |
bpf: add bpf_tcp_gen_syncookie helper
This helper function allows BPF programs to try to generate SYN
cookies, given a reference to a listener socket. The function works
from XDP and with an skb context since bpf_skc_lookup_tcp can lookup a
socket in both cases.
Signed-off-by: Petar Penkov <ppenkov@google.com>
Suggested-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Lorenz Bauer <lmb@cloudflare.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'include/uapi')
| -rw-r--r-- | include/uapi/linux/bpf.h | 30 |
1 files changed, 29 insertions, 1 deletions
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 6bbef0c7f585..4393bd4b2419 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -2714,6 +2714,33 @@ union bpf_attr { * **-EPERM** if no permission to send the *sig*. * * **-EAGAIN** if bpf program can try again. + * + * s64 bpf_tcp_gen_syncookie(struct bpf_sock *sk, void *iph, u32 iph_len, struct tcphdr *th, u32 th_len) + * Description + * Try to issue a SYN cookie for the packet with corresponding + * IP/TCP headers, *iph* and *th*, on the listening socket in *sk*. + * + * *iph* points to the start of the IPv4 or IPv6 header, while + * *iph_len* contains **sizeof**\ (**struct iphdr**) or + * **sizeof**\ (**struct ip6hdr**). + * + * *th* points to the start of the TCP header, while *th_len* + * contains the length of the TCP header. + * + * Return + * On success, lower 32 bits hold the generated SYN cookie in + * followed by 16 bits which hold the MSS value for that cookie, + * and the top 16 bits are unused. + * + * On failure, the returned value is one of the following: + * + * **-EINVAL** SYN cookie cannot be issued due to error + * + * **-ENOENT** SYN cookie should not be issued (no SYN flood) + * + * **-EOPNOTSUPP** kernel configuration does not enable SYN cookies + * + * **-EPROTONOSUPPORT** IP packet version is not 4 or 6 */ #define __BPF_FUNC_MAPPER(FN) \ FN(unspec), \ @@ -2825,7 +2852,8 @@ union bpf_attr { FN(strtoul), \ FN(sk_storage_get), \ FN(sk_storage_delete), \ - FN(send_signal), + FN(send_signal), \ + FN(tcp_gen_syncookie), /* integer value in 'imm' field of BPF_CALL instruction selects which helper * function eBPF program intends to call |