bpf: Be less specific about socket cookies guarantees

Since "92acdc58ab11 bpf, net: Rework cookie generator as per-cpu one"
socket cookies are not guaranteed to be non-decreasing. The
bpf_get_socket_cookie helper descriptions are currently specifying that
cookies are non-decreasing but we don't want users to rely on that.

Reported-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Florent Revest <revest@chromium.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: KP Singh <kpsingh@kernel.org>
Link: https://lore.kernel.org/bpf/20210210111406.785541-1-revest@chromium.org

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index c547ad1..dbf10bf 100644 (file)
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -1656,22 +1656,22 @@ union bpf_attr {
  *             networking traffic statistics as it provides a global socket
  *             identifier that can be assumed unique.
  *     Return
- *             A 8-byte long non-decreasing number on success, or 0 if the
- *             socket field is missing inside *skb*.
+ *             A 8-byte long unique number on success, or 0 if the socket
+ *             field is missing inside *skb*.
  *
  * u64 bpf_get_socket_cookie(struct bpf_sock_addr *ctx)
  *     Description
  *             Equivalent to bpf_get_socket_cookie() helper that accepts
  *             *skb*, but gets socket from **struct bpf_sock_addr** context.
  *     Return
- *             A 8-byte long non-decreasing number.
+ *             A 8-byte long unique number.
  *
  * u64 bpf_get_socket_cookie(struct bpf_sock_ops *ctx)
  *     Description
  *             Equivalent to **bpf_get_socket_cookie**\ () helper that accepts
  *             *skb*, but gets socket from **struct bpf_sock_ops** context.
  *     Return
- *             A 8-byte long non-decreasing number.
+ *             A 8-byte long unique number.
  *
  * u32 bpf_get_socket_uid(struct sk_buff *skb)
  *     Return

diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index c547ad1..dbf10bf 100644 (file)
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -1656,22 +1656,22 @@ union bpf_attr {
  *             networking traffic statistics as it provides a global socket
  *             identifier that can be assumed unique.
  *     Return
- *             A 8-byte long non-decreasing number on success, or 0 if the
- *             socket field is missing inside *skb*.
+ *             A 8-byte long unique number on success, or 0 if the socket
+ *             field is missing inside *skb*.
  *
  * u64 bpf_get_socket_cookie(struct bpf_sock_addr *ctx)
  *     Description
  *             Equivalent to bpf_get_socket_cookie() helper that accepts
  *             *skb*, but gets socket from **struct bpf_sock_addr** context.
  *     Return
- *             A 8-byte long non-decreasing number.
+ *             A 8-byte long unique number.
  *
  * u64 bpf_get_socket_cookie(struct bpf_sock_ops *ctx)
  *     Description
  *             Equivalent to **bpf_get_socket_cookie**\ () helper that accepts
  *             *skb*, but gets socket from **struct bpf_sock_ops** context.
  *     Return
- *             A 8-byte long non-decreasing number.
+ *             A 8-byte long unique number.
  *
  * u32 bpf_get_socket_uid(struct sk_buff *skb)
  *     Return