netdev - [PATCH bpf-next v7 2/6] bpf: Fix documentation of th_len in bpf_tcp_{gen,check}

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Date:   Thu, 28 Apr 2022 18:38:29 +0300
From:   Maxim Mikityanskiy <maximmi@...dia.com>
To:     <bpf@...r.kernel.org>, Alexei Starovoitov <ast@...nel.org>,
        "Daniel Borkmann" <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>, <netdev@...r.kernel.org>
CC:     Tariq Toukan <tariqt@...dia.com>, Martin KaFai Lau <kafai@...com>,
        "Song Liu" <songliubraving@...com>, Yonghong Song <yhs@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...nel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Petar Penkov <ppenkov@...gle.com>,
        Lorenz Bauer <lmb@...udflare.com>,
        Eric Dumazet <edumazet@...gle.com>,
        Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
        "David Ahern" <dsahern@...nel.org>, Shuah Khan <shuah@...nel.org>,
        "Jesper Dangaard Brouer" <hawk@...nel.org>,
        Nathan Chancellor <nathan@...nel.org>,
        "Nick Desaulniers" <ndesaulniers@...gle.com>,
        Joe Stringer <joe@...ium.io>,
        "Florent Revest" <revest@...omium.org>,
        <linux-kselftest@...r.kernel.org>,
        Toke Høiland-Jørgensen <toke@...e.dk>,
        "Kumar Kartikeya Dwivedi" <memxor@...il.com>,
        Florian Westphal <fw@...len.de>, <pabeni@...hat.com>,
        Maxim Mikityanskiy <maximmi@...dia.com>
Subject: [PATCH bpf-next v7 2/6] bpf: Fix documentation of th_len in bpf_tcp_{gen,check}_syncookie

bpf_tcp_gen_syncookie expects the full length of the TCP header (with
all options), and bpf_tcp_check_syncookie accepts lengths bigger than
sizeof(struct tcphdr). Fix the documentation that says these lengths
should be exactly sizeof(struct tcphdr).

While at it, fix a typo in the name of struct ipv6hdr.

Signed-off-by: Maxim Mikityanskiy <maximmi@...dia.com>
Reviewed-by: Tariq Toukan <tariqt@...dia.com>
---
 include/uapi/linux/bpf.h       | 10 ++++++----
 tools/include/uapi/linux/bpf.h | 10 ++++++----
 2 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index d14b10b85e51..5e1679af8282 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -3587,10 +3587,11 @@ union bpf_attr {
  *
  * 		*iph* points to the start of the IPv4 or IPv6 header, while
  * 		*iph_len* contains **sizeof**\ (**struct iphdr**) or
- * 		**sizeof**\ (**struct ip6hdr**).
+ * 		**sizeof**\ (**struct ipv6hdr**).
  *
  * 		*th* points to the start of the TCP header, while *th_len*
- * 		contains **sizeof**\ (**struct tcphdr**).
+ *		contains the length of the TCP header (at least
+ *		**sizeof**\ (**struct tcphdr**)).
  * 	Return
  * 		0 if *iph* and *th* are a valid SYN cookie ACK, or a negative
  * 		error otherwise.
@@ -3773,10 +3774,11 @@ union bpf_attr {
  *
  *		*iph* points to the start of the IPv4 or IPv6 header, while
  *		*iph_len* contains **sizeof**\ (**struct iphdr**) or
- *		**sizeof**\ (**struct ip6hdr**).
+ *		**sizeof**\ (**struct ipv6hdr**).
  *
  *		*th* points to the start of the TCP header, while *th_len*
- *		contains the length of the TCP header.
+ *		contains the length of the TCP header with options (at least
+ *		**sizeof**\ (**struct tcphdr**)).
  *	Return
  *		On success, lower 32 bits hold the generated SYN cookie in
  *		followed by 16 bits which hold the MSS value for that cookie,
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index d14b10b85e51..5e1679af8282 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -3587,10 +3587,11 @@ union bpf_attr {
  *
  * 		*iph* points to the start of the IPv4 or IPv6 header, while
  * 		*iph_len* contains **sizeof**\ (**struct iphdr**) or
- * 		**sizeof**\ (**struct ip6hdr**).
+ * 		**sizeof**\ (**struct ipv6hdr**).
  *
  * 		*th* points to the start of the TCP header, while *th_len*
- * 		contains **sizeof**\ (**struct tcphdr**).
+ *		contains the length of the TCP header (at least
+ *		**sizeof**\ (**struct tcphdr**)).
  * 	Return
  * 		0 if *iph* and *th* are a valid SYN cookie ACK, or a negative
  * 		error otherwise.
@@ -3773,10 +3774,11 @@ union bpf_attr {
  *
  *		*iph* points to the start of the IPv4 or IPv6 header, while
  *		*iph_len* contains **sizeof**\ (**struct iphdr**) or
- *		**sizeof**\ (**struct ip6hdr**).
+ *		**sizeof**\ (**struct ipv6hdr**).
  *
  *		*th* points to the start of the TCP header, while *th_len*
- *		contains the length of the TCP header.
+ *		contains the length of the TCP header with options (at least
+ *		**sizeof**\ (**struct tcphdr**)).
  *	Return
  *		On success, lower 32 bits hold the generated SYN cookie in
  *		followed by 16 bits which hold the MSS value for that cookie,
-- 
2.30.2