From 725721a6506eea53bfde81a34e91a06d6162c216 Mon Sep 17 00:00:00 2001 From: Viet Hoang Tran Date: Mon, 15 Apr 2019 09:54:55 +0000 Subject: [PATCH] bpf: allow clearing all sock_ops callback flags The helper function bpf_sock_ops_cb_flags_set() can be used to both set and clear the sock_ops callback flags. However, its current behavior is not consistent. BPF program may clear a flag if more than one were set, or replace a flag with another one, but cannot clear all flags. This patch also updates the documentation to clarify the ability to clear flags of this helper function. Signed-off-by: Hoang Tran Acked-by: Martin KaFai Lau Signed-off-by: Alexei Starovoitov --- include/uapi/linux/bpf.h | 9 ++++++++- net/core/filter.c | 3 +-- 2 files changed, 9 insertions(+), 3 deletions(-) diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 704bb69514a2..eaf2d3284248 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -1737,12 +1737,19 @@ union bpf_attr { * error if an eBPF program tries to set a callback that is not * supported in the current kernel. * - * The supported callback values that *argval* can combine are: + * *argval* is a flag array which can combine these flags: * * * **BPF_SOCK_OPS_RTO_CB_FLAG** (retransmission time out) * * **BPF_SOCK_OPS_RETRANS_CB_FLAG** (retransmission) * * **BPF_SOCK_OPS_STATE_CB_FLAG** (TCP state change) * + * Therefore, this function can be used to clear a callback flag by + * setting the appropriate bit to zero. e.g. to disable the RTO + * callback: + * + * **bpf_sock_ops_cb_flags_set(bpf_sock,** + * **bpf_sock->bpf_sock_ops_cb_flags & ~BPF_SOCK_OPS_RTO_CB_FLAG)** + * * Here are some examples of where one could call such eBPF * program: * diff --git a/net/core/filter.c b/net/core/filter.c index bd1f51907b83..1833926a63fc 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -4437,8 +4437,7 @@ BPF_CALL_2(bpf_sock_ops_cb_flags_set, struct bpf_sock_ops_kern *, bpf_sock, if (!IS_ENABLED(CONFIG_INET) || !sk_fullsock(sk)) return -EINVAL; - if (val) - tcp_sk(sk)->bpf_sock_ops_cb_flags = val; + tcp_sk(sk)->bpf_sock_ops_cb_flags = val; return argval & (~BPF_SOCK_OPS_ALL_CB_FLAGS); } -- 2.30.2