Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next

Daniel Borkmann says:

====================
The following pull-request contains BPF updates for your *net-next* tree.

There is a small merge conflict in libbpf (Cc Andrii so he's in the loop
as well):

        for (i = 1; i <= btf__get_nr_types(btf); i++) {
                t = (struct btf_type *)btf__type_by_id(btf, i);

                if (!has_datasec && btf_is_var(t)) {
                        /* replace VAR with INT */
                        t->info = BTF_INFO_ENC(BTF_KIND_INT, 0, 0);
  <<<<<<< HEAD
                        /*
                         * using size = 1 is the safest choice, 4 will be too
                         * big and cause kernel BTF validation failure if
                         * original variable took less than 4 bytes
                         */
                        t->size = 1;
                        *(int *)(t+1) = BTF_INT_ENC(0, 0, 8);
                } else if (!has_datasec && kind == BTF_KIND_DATASEC) {
  =======
                        t->size = sizeof(int);
                        *(int *)(t + 1) = BTF_INT_ENC(0, 0, 32);
                } else if (!has_datasec && btf_is_datasec(t)) {
  >>>>>>> 72ef80b5ee131e96172f19e74b4f98fa3404efe8
                        /* replace DATASEC with STRUCT */

Conflict is between the two commits 1d4126c4e119 ("libbpf: sanitize VAR to
conservative 1-byte INT") and b03bc6853c0e ("libbpf: convert libbpf code to
use new btf helpers"), so we need to pick the sanitation fixup as well as
use the new btf_is_datasec() helper and the whitespace cleanup. Looks like
the following:

  [...]
                if (!has_datasec && btf_is_var(t)) {
                        /* replace VAR with INT */
                        t->info = BTF_INFO_ENC(BTF_KIND_INT, 0, 0);
                        /*
                         * using size = 1 is the safest choice, 4 will be too
                         * big and cause kernel BTF validation failure if
                         * original variable took less than 4 bytes
                         */
                        t->size = 1;
                        *(int *)(t + 1) = BTF_INT_ENC(0, 0, 8);
                } else if (!has_datasec && btf_is_datasec(t)) {
                        /* replace DATASEC with STRUCT */
  [...]

The main changes are:

1) Addition of core parts of compile once - run everywhere (co-re) effort,
   that is, relocation of fields offsets in libbpf as well as exposure of
   kernel's own BTF via sysfs and loading through libbpf, from Andrii.

   More info on co-re: http://vger.kernel.org/bpfconf2019.html#session-2
   and http://vger.kernel.org/lpc-bpf2018.html#session-2

2) Enable passing input flags to the BPF flow dissector to customize parsing
   and allowing it to stop early similar to the C based one, from Stanislav.

3) Add a BPF helper function that allows generating SYN cookies from XDP and
   tc BPF, from Petar.

4) Add devmap hash-based map type for more flexibility in device lookup for
   redirects, from Toke.

5) Improvements to XDP forwarding sample code now utilizing recently enabled
   devmap lookups, from Jesper.

6) Add support for reporting the effective cgroup progs in bpftool, from Jakub
   and Takshak.

7) Fix reading kernel config from bpftool via /proc/config.gz, from Peter.

8) Fix AF_XDP umem pages mapping for 32 bit architectures, from Ivan.

9) Follow-up to add two more BPF loop tests for the selftest suite, from Alexei.

10) Add perf event output helper also for other skb-based program types, from Allan.

11) Fix a co-re related compilation error in selftests, from Yonghong.
====================

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>

2 files changed, 35 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/sysfs-kernel-btf b/Documentation/ABI/testing/sysfs-kernel-btf
new file mode 100644
index 000000000000..2c9744b2cd59
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-kernel-btf
@@ -0,0 +1,17 @@
+What:		/sys/kernel/btf
+Date:		Aug 2019
+KernelVersion:	5.5
+Contact:	bpf@vger.kernel.org
+Description:
+		Contains BTF type information and related data for kernel and
+		kernel modules.
+
+What:		/sys/kernel/btf/vmlinux
+Date:		Aug 2019
+KernelVersion:	5.5
+Contact:	bpf@vger.kernel.org
+Description:
+		Read-only binary attribute exposing kernel's own BTF type
+		information with description of all internal kernel types. See
+		Documentation/bpf/btf.rst for detailed description of format
+		itself.
diff --git a/Documentation/bpf/prog_flow_dissector.rst b/Documentation/bpf/prog_flow_dissector.rst
index ed343abe541e..a78bf036cadd 100644
--- a/Documentation/bpf/prog_flow_dissector.rst
+++ b/Documentation/bpf/prog_flow_dissector.rst
@@ -26,6 +26,7 @@ The inputs are:
   * ``nhoff`` - initial offset of the networking header
   * ``thoff`` - initial offset of the transport header, initialized to nhoff
   * ``n_proto`` - L3 protocol type, parsed out of L2 header
+  * ``flags`` - optional flags
 
 Flow dissector BPF program should fill out the rest of the ``struct
 bpf_flow_keys`` fields. Input arguments ``nhoff/thoff/n_proto`` should be
@@ -101,6 +102,23 @@ can be called for both cases and would have to be written carefully to
 handle both cases.
 
 
+Flags
+=====
+
+``flow_keys->flags`` might contain optional input flags that work as follows:
+
+* ``BPF_FLOW_DISSECTOR_F_PARSE_1ST_FRAG`` - tells BPF flow dissector to
+  continue parsing first fragment; the default expected behavior is that
+  flow dissector returns as soon as it finds out that the packet is fragmented;
+  used by ``eth_get_headlen`` to estimate length of all headers for GRO.
+* ``BPF_FLOW_DISSECTOR_F_STOP_AT_FLOW_LABEL`` - tells BPF flow dissector to
+  stop parsing as soon as it reaches IPv6 flow label; used by
+  ``___skb_get_hash`` and ``__skb_get_hash_symmetric`` to get flow hash.
+* ``BPF_FLOW_DISSECTOR_F_STOP_AT_ENCAP`` - tells BPF flow dissector to stop
+  parsing as soon as it reaches encapsulated headers; used by routing
+  infrastructure.
+
+
 Reference Implementation
 ========================