As requested by David Ahern:

- add negative tests (no routes, explicitly unreachable destinations)
  to exercize error handling code paths;
- do not exit on test failures, but instead print a summary of
  passed/failed tests at the end.

Future patches will add TSO and VRF tests.
Signed-off-by: Peter Oskolkov <posk@google.com>
Reviewed-by: David Ahern <dsahern@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

Lightweight tunnels are L3 constructs that are used with IP/IP6.

For example, lwtunnel_xmit is called from ip_output.c and
ip6_output.c only.

Make the dependency explicit at least for LWT-BPF, as now they
call into IP routing.

V2: added "Reported-by" below.
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Peter Oskolkov <posk@google.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org> # build-tested
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

Add new accessor for bpf_object to get opaque struct btf * from it.

struct btf * is needed for all operations with BTF and it's present in
bpf_object. The only thing missing is a way to get it.

Example use-case is to get BTF key_type_id and value_type_id for a map in
bpf_object. It can be done with btf__get_map_kv_tids() but that function
requires struct btf *.

Similar API can be added for struct btf_ext but no use-case for it yet.
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

Add bpf_map__resize() to change max_entries for a map.

Quite often necessary map size is unknown at compile time and can be
calculated only at run time.

Currently the following approach is used to do so:
* bpf_object__open_buffer() to open Elf file from a buffer;
* bpf_object__find_map_by_name() to find relevant map;
* bpf_map__def() to get map attributes and create struct
  bpf_create_map_attr from them;
* update max_entries in bpf_create_map_attr;
* bpf_create_map_xattr() to create new map with updated max_entries;
* bpf_map__reuse_fd() to replace the map in bpf_object with newly
  created one.

And after all this bpf_object can finally be loaded. The map will have
new size.

It 1) is quite a lot of steps; 2) doesn't take BTF into account.

For "2)" even more steps should be made and some of them require changes
to libbpf (e.g. to get struct btf * from bpf_object).

Instead the whole problem can be solved by introducing simple
bpf_map__resize() API that checks the map and sets new max_entries if
the map is not loaded yet.

So the new steps are:
* bpf_object__open_buffer() to open Elf file from a buffer;
* bpf_object__find_map_by_name() to find relevant map;
* bpf_map__resize() to update max_entries.

That's much simpler and works with BTF.
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

Commit c9b47cc1 ("xsk: fix bug when trying to use both copy and
zero-copy on one queue id") moved the umem query code to the AF_XDP
core, and therefore removed the need to query the netdevice for a
umem.

This patch removes XDP_QUERY_XSK_UMEM and all code that implement that
behavior, which is just dead code.
Signed-off-by: Jan Sokolowski <jan.sokolowski@intel.com>
Acked-by: Björn Töpel <bjorn.topel@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

Andrii Nakryiko says:

====================
This patchset replaces bzero() with memset() and syncs if_link.h header
to suppress unsynchronized headers warning.
====================
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

Syncing if_link.h that got out of sync.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

bzero() call is deprecated and superseded by memset().
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Reported-by: David Laight <david.laight@aculab.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

On error the skb should be freed. Tested with diff/steps
provided by David Ahern.

v2: surface routing errors to the user instead of a generic EINVAL,
    as suggested by David Ahern.
Reported-by: David Ahern <dsahern@gmail.com>
Fixes: 3bd0b152 ("bpf: add handling of BPF_LWT_REROUTE to lwt_bpf.c")
Signed-off-by: Peter Oskolkov <posk@google.com>
Reviewed-by: David Ahern <dsahern@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

Peter Oskolkov says:

====================
This patchset implements BPF_LWT_ENCAP_IP mode in bpf_lwt_push_encap
BPF helper. It enables BPF programs (specifically, BPF_PROG_TYPE_LWT_IN
and BPF_PROG_TYPE_LWT_XMIT prog types) to add IP encapsulation headers
to packets (e.g. IP/GRE, GUE, IPIP).

This is useful when thousands of different short-lived flows should be
encapped, each with different and dynamically determined destination.
Although lwtunnels can be used in some of these scenarios, the ability
to dynamically generate encap headers adds more flexibility, e.g.
when routing depends on the state of the host (reflected in global bpf
maps).

V2 changes: added flowi-based route lookup, IPv6 encapping, and
   encapping on ingress.

V3 changes: incorporated David Ahern's suggestions:
   - added l3mdev check/oif (patch 2)
   - sync bpf.h from include/uapi into tools/include/uapi
   - selftest tweaks

V4 changes: moved route lookup/dst change from bpf_push_ip_encap
   to when BPF_LWT_REROUTE is handled, as suggested by David Ahern.

V5 changes: added a check in lwt_xmit that skb->protocol stays the
   same if the skb is to be passed back to the stack (ret == BPF_OK).
   Again, suggested by David Ahern.

V6 changes: abandoned.

V7 changes: added handling of GSO packets (patch 3 in the patchset added),
   as suggested by BPF maintainers.

V8 changes:
   - fixed build errors when LWT or IPV6 are not enabled;
   - whitelisted TCP GSO instead of blacklisting SCTP and UDP GSO, as
     suggested by Willem de Bruijn;
   - added validation that pushed length cover needed headers when GRE/UDP
     encap is detected, as suggested by Willem de Bruijn;
   - a couple of minor/stylistic tweaks/fixed typos.

V9 changes:
   - fixed a kbuild test robot compiler warning;
   - added ipv6_route_input to ipv6_stub (patch 4 in the patchset
     added), and IPv6 routing functions are now invoked via ipv6_stub,
     as suggested by David Ahern.

V10 changes:
   - removed unnecessary IS_ENABLED and pr_warn_once from patch 5.

V11 changes: fixed a potential dst leak in patch 5, as suggested by
    David Ahern.
====================
Reviewed-by: David Ahern <dsahern@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

This patch adds a bpf self-test to cover BPF_LWT_ENCAP_IP mode
in bpf_lwt_push_encap.

Covered:
- encapping in LWT_IN and LWT_XMIT
- IPv4 and IPv6

A follow-up patch will add GSO and VRF-enabled tests.
Signed-off-by: Peter Oskolkov <posk@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

This patch copies changes in bpf.h done by a previous patch
in this patchset from the kernel uapi include dir into tools
uapi include dir.
Signed-off-by: Peter Oskolkov <posk@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

This patch builds on top of the previous patch in the patchset,
which added BPF_LWT_ENCAP_IP mode to bpf_lwt_push_encap. As the
encapping can result in the skb needing to go via a different
interface/route/dst, bpf programs can indicate this by returning
BPF_LWT_REROUTE, which triggers a new route lookup for the skb.

v8 changes: fix kbuild errors when LWTUNNEL_BPF is builtin, but
   IPV6 is a module: as LWTUNNEL_BPF can only be either Y or N,
   call IPV6 routing functions only if they are built-in.

v9 changes:
   - fixed a kbuild test robot compiler warning;
   - call IPV6 routing functions via ipv6_stub.

v10 changes: removed unnecessary IS_ENABLED and pr_warn_once.

v11 changes: fixed a potential dst leak.
Signed-off-by: Peter Oskolkov <posk@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

Proxy ip6_route_input via ipv6_stub, for later use by lwt bpf ip encap
(see the next patch in the patchset).
Signed-off-by: Peter Oskolkov <posk@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

This patch adds handling of GSO packets in bpf_lwt_push_ip_encap()
(called from bpf_lwt_push_encap):

* IPIP, GRE, and UDP encapsulation types are deduced by looking
  into iphdr->protocol or ipv6hdr->next_header;
* SCTP GSO packets are not supported (as bpf_skb_proto_4_to_6
  and similar do);
* UDP_L4 GSO packets are also not supported (although they are
  not blocked in bpf_skb_proto_4_to_6 and similar), as
  skb_decrease_gso_size() will break it;
* SKB_GSO_DODGY bit is set.

Note: it may be possible to support SCTP and UDP_L4 gso packets;
      but as these cases seem to be not well handled by other
      tunneling/encapping code paths, the solution should
      be generic enough to apply to all tunneling/encapping code.

v8 changes:
   - make sure that if GRE or UDP encap is detected, there is
     enough of pushed bytes to cover both IP[v6] + GRE|UDP headers;
   - do not reject double-encapped packets;
   - whitelist TCP GSO packets rather than block SCTP GSO and
     UDP GSO.
Signed-off-by: Peter Oskolkov <posk@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

Implement BPF_LWT_ENCAP_IP mode in bpf_lwt_push_encap BPF helper.
It enables BPF programs (specifically, BPF_PROG_TYPE_LWT_IN and
BPF_PROG_TYPE_LWT_XMIT prog types) to add IP encapsulation headers
to packets (e.g. IP/GRE, GUE, IPIP).

This is useful when thousands of different short-lived flows should be
encapped, each with different and dynamically determined destination.
Although lwtunnels can be used in some of these scenarios, the ability
to dynamically generate encap headers adds more flexibility, e.g.
when routing depends on the state of the host (reflected in global bpf
maps).

v7 changes:
 - added a call skb_clear_hash();
 - removed calls to skb_set_transport_header();
 - refuse to encap GSO-enabled packets.

v8 changes:
 - fix build errors when LWT is not enabled.

Note: the next patch in the patchset with deal with GSO-enabled packets,
which are currently rejected at encapping attempt.
Signed-off-by: Peter Oskolkov <posk@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

This patch adds all needed plumbing in preparation to allowing
bpf programs to do IP encapping via bpf_lwt_push_encap. Actual
implementation is added in the next patch in the patchset.

Of note:
- bpf_lwt_push_encap can now be called from BPF_PROG_TYPE_LWT_XMIT
  prog types in addition to BPF_PROG_TYPE_LWT_IN;
- if the skb being encapped has GSO set, encapsulation is limited
  to IPIP/IP+GRE/IP+GUE (both IPv4 and IPv6);
- as route lookups are different for ingress vs egress, the single
  external bpf_lwt_push_encap BPF helper is routed internally to
  either bpf_lwt_in_push_encap or bpf_lwt_xmit_push_encap BPF_CALLs,
  depending on prog type.

v8 changes: fixed a typo.
Signed-off-by: Peter Oskolkov <posk@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

Currently bpf_offload_dev does not have any priv pointer, forcing
the drivers to work backwards from the netdev in program metadata.
This is not great given programs are conceptually associated with
the offload device, and it means one or two unnecessary deferences.
Add a priv pointer to bpf_offload_dev.
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

This patch adds missing information about feature-subcommand in
bpftool.rst
Signed-off-by: Prashant Bhole <bhole_prashant_q7@lab.ntt.co.jp>
Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

Jiong Wang says:

====================
This set improves bpf object file related rules in selftests Makefile.
  - tell git to ignore the build dir "alu32".
  - extend sub-register mode compilation to all bpf object files to give
    LLVM compiler bpf back-end more exercise.
  - auto-generate bpf kernel object file list.
  - relax sub-register mode compilation criteria.

v1 -> v2:
  - rename "kern_progs" to "progs". (Alexei)
  - spin a new patch to remove build server kernel requirement for
    sub-register mode compilation (Alexei)
  - rebase on top of KaFai’s latest "test_sock_fields" patch set.
====================
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

Sub-register mode compilation was enabled only when there are eBPF "v3"
processor supports at both compilation time inside LLVM and runtime inside
kernel.

Given separation betwen build and test server could be often, this patch
removes the runtime support criteria.
Suggested-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Jiong Wang <jiong.wang@netronome.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

At the moment, all kernel bpf objects are listed under BPF_OBJ_FILES.
Listing them manually sometimes causing patch conflict when people are
adding new testcases simultaneously.

It is better to centre all the related source files under a subdir
"progs", then auto-generate the object file list.
Suggested-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Jiong Wang <jiong.wang@netronome.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

At the moment, we only do extra sub-register mode compilation on bpf object
files used by "test_progs". These object files are really loaded and
executed.

This patch further extends sub-register mode compilation to all bpf object
files, even those without corresponding runtime tests. Because this could
help testing LLVM sub-register code-gen, kernel bpf selftest has much more
C testcases with reasonable size and complexity compared with LLVM
testsuite which only contains unit tests.

There were some file duplication inside BPF_OBJ_FILES_DUAL_COMPILE which
is removed now.
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Jiong Wang <jiong.wang@netronome.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

"alu32" is a build dir and contains various files for BPF sub-register
code-gen testing.

This patch tells git to ignore it.
Suggested-by: Yonghong Song <yhs@fb.com>
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Jiong Wang <jiong.wang@netronome.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

Martin KaFai Lau says:

====================
This series adds __sk_buff->sk, "struct bpf_tcp_sock",
BPF_FUNC_sk_fullsock and BPF_FUNC_tcp_sock.  Together, they provide
a common way to expose the members of "struct tcp_sock" and
"struct bpf_sock" for the bpf_prog to access.

The patch series first adds a bpf_sock pointer to __sk_buff
and a new helper BPF_FUNC_sk_fullsock.

It then adds BPF_FUNC_tcp_sock to get a bpf_tcp_sock
pointer from a bpf_sock pointer.

The current use case is to allow a cg_skb_bpf_prog to provide
per cgroup traffic policing/shaping.

Please see individual patch for details.

v2:
- Patch 1 depends on
  commit d6238766 ("bpf: Fix narrow load on a bpf_sock returned from sk_lookup()")
  in the bpf branch.
- Add sk_to_full_sk() to bpf_sk_fullsock() and bpf_tcp_sock()
  such that there is a way to access the listener's sk and tcp_sk
  when __sk_buff->sk is a request_sock.
  The comments in the uapi bpf.h is updated accordingly.
- bpf_ctx_range_till() is used in bpf_sock_common_is_valid_access()
  in patch 1.  Saved a few lines.
- Patch 2 is new in v2 and it adds "state", "dst_ip4", "dst_ip6" and
  "dst_port" to the bpf_sock.  Narrow load is allowed on them.
  The "state" (i.e. sk_state) has already been used in
  INET_DIAG (e.g. ss -t) and getsockopt(TCP_INFO).
- While at it in the new patch 2, also allow narrow load on some
  existing fields of the bpf_sock, which are "family", "type", "protocol"
  and "src_port".  Only allow loading from first byte for now.
  i.e. does not allow narrow load starting from the 2nd byte.
- Add some narrow load tests to the test_verifier's sock.c
====================
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

This patch adds a C program to show the usage on
skb->sk and bpf_tcp_sock.
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

This patch tests accessing the skb->sk and the new helpers,
bpf_sk_fullsock and bpf_tcp_sock.

The errstr of some existing "reference tracking" tests is changed
with s/bpf_sock/sock/ and s/socket/sock/ where "sock" is from the
verifier's reg_type_str[].
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

This patch sync the uapi bpf.h to tools/.
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

This patch adds a helper function BPF_FUNC_tcp_sock and it
is currently available for cg_skb and sched_(cls|act):

struct bpf_tcp_sock *bpf_tcp_sock(struct bpf_sock *sk);

int cg_skb_foo(struct __sk_buff *skb) {
	struct bpf_tcp_sock *tp;
	struct bpf_sock *sk;
	__u32 snd_cwnd;

	sk = skb->sk;
	if (!sk)
		return 1;

	tp = bpf_tcp_sock(sk);
	if (!tp)
		return 1;

	snd_cwnd = tp->snd_cwnd;
	/* ... */

	return 1;
}

A 'struct bpf_tcp_sock' is also added to the uapi bpf.h to provide
read-only access.  bpf_tcp_sock has all the existing tcp_sock's fields
that has already been exposed by the bpf_sock_ops.
i.e. no new tcp_sock's fields are exposed in bpf.h.

This helper returns a pointer to the tcp_sock.  If it is not a tcp_sock
or it cannot be traced back to a tcp_sock by sk_to_full_sk(), it
returns NULL.  Hence, the caller needs to check for NULL before
accessing it.

The current use case is to expose members from tcp_sock
to allow a cg_skb_bpf_prog to provide per cgroup traffic
policing/shaping.
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

The next patch will introduce a new "struct bpf_tcp_sock" which
exposes the same tcp_sock's fields already exposed in
"struct bpf_sock_ops".

This patch refactor the existing convert_ctx_access() codes for
"struct bpf_sock_ops" to get them ready to be reused for
"struct bpf_tcp_sock".  The "rtt_min" is not refactored
in this patch because its handling is different from other
fields.

The SOCK_OPS_GET_TCP_SOCK_FIELD is new. All other SOCK_OPS_XXX_FIELD
changes are code move only.
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

This patch adds "state", "dst_ip4", "dst_ip6" and "dst_port" to the
bpf_sock.  The userspace has already been using "state",
e.g. inet_diag (ss -t) and getsockopt(TCP_INFO).

This patch also allows narrow load on the following existing fields:
"family", "type", "protocol" and "src_port".  Unlike IP address,
the load offset is resticted to the first byte for them but it
can be relaxed later if there is a use case.

This patch also folds __sock_filter_check_size() into
bpf_sock_is_valid_access() since it is not called
by any where else.  All bpf_sock checking is in
one place.
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

In kernel, it is common to check "skb->sk && sk_fullsock(skb->sk)"
before accessing the fields in sock.  For example, in __netdev_pick_tx:

static u16 __netdev_pick_tx(struct net_device *dev, struct sk_buff *skb,
			    struct net_device *sb_dev)
{
	/* ... */

	struct sock *sk = skb->sk;

		if (queue_index != new_index && sk &&
		    sk_fullsock(sk) &&
		    rcu_access_pointer(sk->sk_dst_cache))
			sk_tx_queue_set(sk, new_index);

	/* ... */

	return queue_index;
}

This patch adds a "struct bpf_sock *sk" pointer to the "struct __sk_buff"
where a few of the convert_ctx_access() in filter.c has already been
accessing the skb->sk sock_common's fields,
e.g. sock_ops_convert_ctx_access().

"__sk_buff->sk" is a PTR_TO_SOCK_COMMON_OR_NULL in the verifier.
Some of the fileds in "bpf_sock" will not be directly
accessible through the "__sk_buff->sk" pointer.  It is limited
by the new "bpf_sock_common_is_valid_access()".
e.g. The existing "type", "protocol", "mark" and "priority" in bpf_sock
     are not allowed.

The newly added "struct bpf_sock *bpf_sk_fullsock(struct bpf_sock *sk)"
can be used to get a sk with all accessible fields in "bpf_sock".
This helper is added to both cg_skb and sched_(cls|act).

int cg_skb_foo(struct __sk_buff *skb) {
	struct bpf_sock *sk;

	sk = skb->sk;
	if (!sk)
		return 1;

	sk = bpf_sk_fullsock(sk);
	if (!sk)
		return 1;

	if (sk->family != AF_INET6 || sk->protocol != IPPROTO_TCP)
		return 1;

	/* some_traffic_shaping(); */

	return 1;
}

(1) The sk is read only

(2) There is no new "struct bpf_sock_common" introduced.

(3) Future kernel sock's members could be added to bpf_sock only
    instead of repeatedly adding at multiple places like currently
    in bpf_sock_ops_md, bpf_sock_addr_md, sk_reuseport_md...etc.

(4) After "sk = skb->sk", the reg holding sk is in type
    PTR_TO_SOCK_COMMON_OR_NULL.

(5) After bpf_sk_fullsock(), the return type will be in type
    PTR_TO_SOCKET_OR_NULL which is the same as the return type of
    bpf_sk_lookup_xxx().

    However, bpf_sk_fullsock() does not take refcnt.  The
    acquire_reference_state() is only depending on the return type now.
    To avoid it, a new is_acquire_function() is checked before calling
    acquire_reference_state().

(6) The WARN_ON in "release_reference_state()" is no longer an
    internal verifier bug.

    When reg->id is not found in state->refs[], it means the
    bpf_prog does something wrong like
    "bpf_sk_release(bpf_sk_fullsock(skb->sk))" where reference has
    never been acquired by calling "bpf_sk_fullsock(skb->sk)".

    A -EINVAL and a verbose are done instead of WARN_ON.  A test is
    added to the test_verifier in a later patch.

    Since the WARN_ON in "release_reference_state()" is no longer
    needed, "__release_reference_state()" is folded into
    "release_reference_state()" also.
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

By adding this test to test_verifier:
{
	"reference tracking: access sk->src_ip4 (narrow load)",
	.insns = {
	BPF_SK_LOOKUP,
	BPF_MOV64_REG(BPF_REG_6, BPF_REG_0),
	BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 3),
	BPF_LDX_MEM(BPF_H, BPF_REG_2, BPF_REG_0, offsetof(struct bpf_sock, src_ip4) + 2),
	BPF_MOV64_REG(BPF_REG_1, BPF_REG_6),
	BPF_EMIT_CALL(BPF_FUNC_sk_release),
	BPF_EXIT_INSN(),
	},
	.prog_type = BPF_PROG_TYPE_SCHED_CLS,
	.result = ACCEPT,
},

The above test loads 2 bytes from sk->src_ip4 where
sk is obtained by bpf_sk_lookup_tcp().

It hits an internal verifier error from convert_ctx_accesses():
[root@arch-fb-vm1 bpf]# ./test_verifier 665 665
Failed to load prog 'Invalid argument'!
0: (b7) r2 = 0
1: (63) *(u32 *)(r10 -8) = r2
2: (7b) *(u64 *)(r10 -16) = r2
3: (7b) *(u64 *)(r10 -24) = r2
4: (7b) *(u64 *)(r10 -32) = r2
5: (7b) *(u64 *)(r10 -40) = r2
6: (7b) *(u64 *)(r10 -48) = r2
7: (bf) r2 = r10
8: (07) r2 += -48
9: (b7) r3 = 36
10: (b7) r4 = 0
11: (b7) r5 = 0
12: (85) call bpf_sk_lookup_tcp#84
13: (bf) r6 = r0
14: (15) if r0 == 0x0 goto pc+3
 R0=sock(id=1,off=0,imm=0) R6=sock(id=1,off=0,imm=0) R10=fp0,call_-1 fp-8=????0000 fp-16=0000mmmm fp-24=mmmmmmmm fp-32=mmmmmmmm fp-40=mmmmmmmm fp-48=mmmmmmmm refs=1
15: (69) r2 = *(u16 *)(r0 +26)
16: (bf) r1 = r6
17: (85) call bpf_sk_release#86
18: (95) exit

from 14 to 18: safe
processed 20 insns (limit 131072), stack depth 48
bpf verifier is misconfigured
Summary: 0 PASSED, 0 SKIPPED, 1 FAILED

The bpf_sock_is_valid_access() is expecting src_ip4 can be narrowly
loaded (meaning load any 1 or 2 bytes of the src_ip4) by
marking info->ctx_field_size.  However, this marked
ctx_field_size is not used.  This patch fixes it.

Due to the recent refactoring in test_verifier,
this new test will be added to the bpf-next branch
(together with the bpf_tcp_sock patchset)
to avoid merge conflict.

Fixes: c64b7983 ("bpf: Add PTR_TO_SOCKET verifier type")
Cc: Joe Stringer <joe@wand.net.nz>
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Joe Stringer <joe@wand.net.nz>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

Andrii Nakryiko says:

====================
This patchset introduces a set of new APIs that make it possible to work with BTF
more effectively (and without involving kernel) for applications like pahole that
need to manipulate .BTF and .BTF.ext data.

Patch #1 changes existing btf__new() API call to only load and initialize
struct btf, while exposing new btf__load() API to attempt to load and validate
BTF in kernel.

Patch #2 adds btf__get_raw_data() API allowing to get access to raw BTF data from
struct btf.

Patch #3 adds similar btf_ext__get_raw_data() API for working with struct btf_ext.

Patch #4 removes not-yet-stable btf__get_strings() API which was added to be able
to test contents of struct btf for btf__dedup(). It's now superseded by raw APIs.

v3->v4:
- formatting fixes
- renamed btf_ext functions/structs to use "setup" language instead of "copy"
- removed btf__get_strings from libbpf.map

v2->v3:
- const void* variants of btf__get_raw_data()
- added btf_ext__get_raw_data()
- removed btf__get_strings() and adapted test_btf.c to use btf__get_raw_data()

v1->v2:
- btf_load() returns just error, not fd
- fix ordering in libbpf.map
====================
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

Now that we have btf__get_raw_data() it's trivial for tests to iterate
over all strings for testing purposes, which eliminates the need for
btf__get_strings() API.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

This patch changes struct btf_ext to retain original data in sequential
block of memory, which makes it possible to expose
btf_ext__get_raw_data() interface similar to btf__get_raw_data(), allowing
users of libbpf to get access to raw representation of .BTF.ext section.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

This patch exposes new API btf__get_raw_data() that allows to get a copy
of raw BTF data out of struct btf. This is useful for external programs
that need to manipulate raw data, e.g., pahole using btf__dedup() to
deduplicate BTF type info and then writing it back to file.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

This change splits out previous btf__new functionality of constructing
struct btf and loading it into kernel into two:
- btf__new() just creates and initializes struct btf
- btf__load() attempts to load existing struct btf into kernel

btf__free will still close BTF fd, if it was ever loaded successfully
into kernel.

This change allows users of libbpf to manipulate BTF using its API,
without the need to unnecessarily load it into kernel.

One of the intended use cases is pahole, which will do DWARF to BTF
conversion and then use libbpf to do type deduplication, while then
handling ELF sections overwriting and other concerns on its own.

Fixes: 2d3feca8 ("bpf: btf: print map dump and lookup with btf info")
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

The kernel verifier has three levels of logs:
    0: no logs
    1: logs mostly useful
  > 1: verbose

Current libbpf API functions bpf_load_program_xattr() and
bpf_load_program() cannot specify log_level.
The bcc, however, provides an interface for user to
specify log_level 2 for verbose output.

This patch added log_level into structure
bpf_load_program_attr, so users, including bcc, can use
bpf_load_program_xattr() to change log_level. The
supported log_level is 0, 1, and 2.

The bpf selftest test_sock.c is modified to enable log_level = 2.
If the "verbose" in test_sock.c is changed to true,
the test will output logs like below:
  $ ./test_sock
  func#0 @0
  0: R1=ctx(id=0,off=0,imm=0) R10=fp0,call_-1
  0: (bf) r6 = r1
  1: R1=ctx(id=0,off=0,imm=0) R6_w=ctx(id=0,off=0,imm=0) R10=fp0,call_-1
  1: (61) r7 = *(u32 *)(r6 +28)
  invalid bpf_context access off=28 size=4

  Test case: bind4 load with invalid access: src_ip6 .. [PASS]
  ...
  Test case: bind6 allow all .. [PASS]
  Summary: 16 PASSED, 0 FAILED

Some test_sock tests are negative tests and verbose verifier
log will be printed out as shown in the above.
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

Few files in libbpf are using bzero() function (defined in strings.h header), but
don't include corresponding header. When libbpf is added as a dependency to pahole,
this undeterministically causes warnings on some machines:

bpf.c:225:2: warning: implicit declaration of function 'bzero' [-Wimplicit-function-declaration]
  bzero(&attr, sizeof(attr));
    ^~~~~
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Reported-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>