In this commit the XSKMAP entry lookup function used by the XDP
redirect code is moved from the xskmap.c file to the xdp_sock.h
header, so the lookup can be inlined from, e.g., the
bpf_xdp_redirect_map() function.

Further the __xsk_map_redirect() and __xsk_map_flush() is moved to the
xsk.c, which lets the compiler inline the xsk_rcv() and xsk_flush()
functions.

Finally, all the XDP socket functions were moved from linux/bpf.h to
net/xdp_sock.h, where most of the XDP sockets functions are anyway.

This yields a ~2% performance boost for the xdpsock "rx_drop"
scenario.
Signed-off-by: NBjörn Töpel <bjorn.topel@intel.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20191101110346.15004-4-bjorn.topel@gmail.com

The bpf program type raw_tp together with 'expected_attach_type'
was the most appropriate api to indicate BTF-enabled raw_tp programs.
But during development it became apparent that 'expected_attach_type'
cannot be used and new 'attach_btf_id' field had to be introduced.
Which means that the information is duplicated in two fields where
one of them is ignored.
Clean it up by introducing new program type where both
'expected_attach_type' and 'attach_btf_id' fields have
specific meaning.
In the future 'expected_attach_type' will be extended
with other attach points that have similar semantics to raw_tp.
This patch is replacing BTF-enabled BPF_PROG_TYPE_RAW_TRACEPOINT with
prog_type = BPF_RPOG_TYPE_TRACING
expected_attach_type = BPF_TRACE_RAW_TP
attach_btf_id = btf_id of raw tracepoint inside the kernel
Future patches will add
expected_attach_type = BPF_TRACE_FENTRY or BPF_TRACE_FEXIT
where programs have the same input context and the same helpers,
but different attach points.
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Acked-by: NAndrii Nakryiko <andriin@fb.com>
Acked-by: NMartin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20191030223212.953010-2-ast@kernel.org

This patch makes a few changes to btf_ctx_access() to prepare
it for non raw_tp use case where the attach_btf_id is not
necessary a BTF_KIND_TYPEDEF.

It moves the "btf_trace_" prefix check and typedef-follow logic to a new
function "check_attach_btf_id()" which is called only once during
bpf_check().  btf_ctx_access() only operates on a BTF_KIND_FUNC_PROTO
type now. That should also be more efficient since it is done only
one instead of every-time check_ctx_access() is called.

"check_attach_btf_id()" needs to find the func_proto type from
the attach_btf_id.  It needs to store the result into the
newly added prog->aux->attach_func_proto.  func_proto
btf type has no name, so a proper name should be stored into
"attach_func_name" also.

v2:
- Move the "btf_trace_" check to an earlier verifier phase (Alexei)
Signed-off-by: NMartin KaFai Lau <kafai@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20191025001811.1718491-1-kafai@fb.com

Introduce new helper that reuses existing skb perf_event output
implementation, but can be called from raw_tracepoint programs
that receive 'struct sk_buff *' as tracepoint argument or
can walk other kernel data structures to skb pointer.

In order to do that teach verifier to resolve true C types
of bpf helpers into in-kernel BTF ids.
The type of kernel pointer passed by raw tracepoint into bpf
program will be tracked by the verifier all the way until
it's passed into helper function.
For example:
kfree_skb() kernel function calls trace_kfree_skb(skb, loc);
bpf programs receives that skb pointer and may eventually
pass it into bpf_skb_output() bpf helper which in-kernel is
implemented via bpf_skb_event_output() kernel function.
Its first argument in the kernel is 'struct sk_buff *'.
The verifier makes sure that types match all the way.
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Acked-by: NAndrii Nakryiko <andriin@fb.com>
Acked-by: NMartin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20191016032505.2089704-11-ast@kernel.org

Pointer to BTF object is a pointer to kernel object or NULL.
Such pointers can only be used by BPF_LDX instructions.
The verifier changed their opcode from LDX|MEM|size
to LDX|PROBE_MEM|size to make JITing easier.
The number of entries in extable is the number of BPF_LDX insns
that access kernel memory via "pointer to BTF type".
Only these load instructions can fault.
Since x86 extable is relative it has to be allocated in the same
memory region as JITed code.
Allocate it prior to last pass of JITing and let the last pass populate it.
Pointer to extable in bpf_prog_aux is necessary to make page fault
handling fast.
Page fault handling is done in two steps:
1. bpf_prog_kallsyms_find() finds BPF program that page faulted.
   It's done by walking rb tree.
2. then extable for given bpf program is binary searched.
This process is similar to how page faulting is done for kernel modules.
The exception handler skips over faulting x86 instruction and
initializes destination register with zero. This mimics exact
behavior of bpf_probe_read (when probe_kernel_read faults dest is zeroed).

JITs for other architectures can add support in similar way.
Until then they will reject unknown opcode and fallback to interpreter.

Since extable should be aligned and placed near JITed code
make bpf_jit_binary_alloc() return 4 byte aligned image offset,
so that extable aligning formula in bpf_int_jit_compile() doesn't need
to rely on internal implementation of bpf_jit_binary_alloc().
On x86 gcc defaults to 16-byte alignment for regular kernel functions
due to better performance. JITed code may be aligned to 16 in the future,
but it will use 4 in the meantime.
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Acked-by: NAndrii Nakryiko <andriin@fb.com>
Acked-by: NMartin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20191016032505.2089704-10-ast@kernel.org

libbpf analyzes bpf C program, searches in-kernel BTF for given type name
and stores it into expected_attach_type.
The kernel verifier expects this btf_id to point to something like:
typedef void (*btf_trace_kfree_skb)(void *, struct sk_buff *skb, void *loc);
which represents signature of raw_tracepoint "kfree_skb".

Then btf_ctx_access() matches ctx+0 access in bpf program with 'skb'
and 'ctx+8' access with 'loc' arguments of "kfree_skb" tracepoint.
In first case it passes btf_id of 'struct sk_buff *' back to the verifier core
and 'void *' in second case.

Then the verifier tracks PTR_TO_BTF_ID as any other pointer type.
Like PTR_TO_SOCKET points to 'struct bpf_sock',
PTR_TO_TCP_SOCK points to 'struct bpf_tcp_sock', and so on.
PTR_TO_BTF_ID points to in-kernel structs.
If 1234 is btf_id of 'struct sk_buff' in vmlinux's BTF
then PTR_TO_BTF_ID#1234 points to one of in kernel skbs.

When PTR_TO_BTF_ID#1234 is dereferenced (like r2 = *(u64 *)r1 + 32)
the btf_struct_access() checks which field of 'struct sk_buff' is
at offset 32. Checks that size of access matches type definition
of the field and continues to track the dereferenced type.
If that field was a pointer to 'struct net_device' the r2's type
will be PTR_TO_BTF_ID#456. Where 456 is btf_id of 'struct net_device'
in vmlinux's BTF.

Such verifier analysis prevents "cheating" in BPF C program.
The program cannot cast arbitrary pointer to 'struct sk_buff *'
and access it. C compiler would allow type cast, of course,
but the verifier will notice type mismatch based on BPF assembly
and in-kernel BTF.
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Acked-by: NAndrii Nakryiko <andriin@fb.com>
Acked-by: NMartin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20191016032505.2089704-7-ast@kernel.org

Add attach_btf_id attribute to prog_load command.
It's similar to existing expected_attach_type attribute which is
used in several cgroup based program types.
Unfortunately expected_attach_type is ignored for
tracing programs and cannot be reused for new purpose.
Hence introduce attach_btf_id to verify bpf programs against
given in-kernel BTF type id at load time.
It is strictly checked to be valid for raw_tp programs only.
In a later patches it will become:
btf_id == 0 semantics of existing raw_tp progs.
btd_id > 0 raw_tp with BTF and additional type safety.
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Acked-by: NAndrii Nakryiko <andriin@fb.com>
Acked-by: NMartin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20191016032505.2089704-5-ast@kernel.org

Do not risk spanning these small structures on two cache lines.
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20191011181140.2898-1-edumazet@google.com

Add a new command for the bpf() system call: BPF_BTF_GET_NEXT_ID is used
to cycle through all BTF objects loaded on the system.

The motivation is to be able to inspect (list) all BTF objects presents
on the system.
Signed-off-by: NQuentin Monnet <quentin.monnet@netronome.com>
Reviewed-by: NJakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>

Rename existing bpf_map_inc_not_zero to __bpf_map_inc_not_zero to
indicate that it's caller's responsibility to do proper locking.
Create and export bpf_map_inc_not_zero wrapper that properly
locks map_idr_lock. Will be used in the next commit to
hold a map while cloning a socket.

Cc: Martin KaFai Lau <kafai@fb.com>
Cc: Yonghong Song <yhs@fb.com>
Acked-by: NMartin KaFai Lau <kafai@fb.com>
Acked-by: NYonghong Song <yhs@fb.com>
Signed-off-by: NStanislav Fomichev <sdf@google.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

A common pattern when using xdp_redirect_map() is to create a device map
where the lookup key is simply ifindex. Because device maps are arrays,
this leaves holes in the map, and the map has to be sized to fit the
largest ifindex, regardless of how many devices actually are actually
needed in the map.

This patch adds a second type of device map where the key is looked up
using a hashmap, instead of being used as an array index. This allows maps
to be densely packed, so they can be smaller.
Signed-off-by: NToke Høiland-Jørgensen <toke@redhat.com>
Acked-by: NYonghong Song <yhs@fb.com>
Acked-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>

When we changed the device and CPU maps to use linked lists instead of
bitmaps, we also removed the need for the map_insert_ctx() helpers to keep
track of the bitmaps inside each map. However, it seems I forgot to remove
the function definitions stubs, so remove those here.
Signed-off-by: NToke Høiland-Jørgensen <toke@redhat.com>
Acked-by: NYonghong Song <yhs@fb.com>
Acked-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>

Implement new BPF_PROG_TYPE_CGROUP_SOCKOPT program type and
BPF_CGROUP_{G,S}ETSOCKOPT cgroup hooks.

BPF_CGROUP_SETSOCKOPT can modify user setsockopt arguments before
passing them down to the kernel or bypass kernel completely.
BPF_CGROUP_GETSOCKOPT can can inspect/modify getsockopt arguments that
kernel returns.
Both hooks reuse existing PTR_TO_PACKET{,_END} infrastructure.

The buffer memory is pre-allocated (because I don't think there is
a precedent for working with __user memory from bpf). This might be
slow to do for each {s,g}etsockopt call, that's why I've added
__cgroup_bpf_prog_array_is_empty that exits early if there is nothing
attached to a cgroup. Note, however, that there is a race between
__cgroup_bpf_prog_array_is_empty and BPF_PROG_RUN_ARRAY where cgroup
program layout might have changed; this should not be a problem
because in general there is a race between multiple calls to
{s,g}etsocktop and user adding/removing bpf progs from a cgroup.

The return code of the BPF program is handled as follows:
* 0: EPERM
* 1: success, continue with next BPF program in the cgroup chain

v9:
* allow overwriting setsockopt arguments (Alexei Starovoitov):
  * use set_fs (same as kernel_setsockopt)
  * buffer is always kzalloc'd (no small on-stack buffer)

v8:
* use s32 for optlen (Andrii Nakryiko)

v7:
* return only 0 or 1 (Alexei Starovoitov)
* always run all progs (Alexei Starovoitov)
* use optval=0 as kernel bypass in setsockopt (Alexei Starovoitov)
  (decided to use optval=-1 instead, optval=0 might be a valid input)
* call getsockopt hook after kernel handlers (Alexei Starovoitov)

v6:
* rework cgroup chaining; stop as soon as bpf program returns
  0 or 2; see patch with the documentation for the details
* drop Andrii's and Martin's Acked-by (not sure they are comfortable
  with the new state of things)

v5:
* skip copy_to_user() and put_user() when ret == 0 (Martin Lau)

v4:
* don't export bpf_sk_fullsock helper (Martin Lau)
* size != sizeof(__u64) for uapi pointers (Martin Lau)
* offsetof instead of bpf_ctx_range when checking ctx access (Martin Lau)

v3:
* typos in BPF_PROG_CGROUP_SOCKOPT_RUN_ARRAY comments (Andrii Nakryiko)
* reverse christmas tree in BPF_PROG_CGROUP_SOCKOPT_RUN_ARRAY (Andrii
  Nakryiko)
* use __bpf_md_ptr instead of __u32 for optval{,_end} (Martin Lau)
* use BPF_FIELD_SIZEOF() for consistency (Martin Lau)
* new CG_SOCKOPT_ACCESS macro to wrap repeated parts

v2:
* moved bpf_sockopt_kern fields around to remove a hole (Martin Lau)
* aligned bpf_sockopt_kern->buf to 8 bytes (Martin Lau)
* bpf_prog_array_is_empty instead of bpf_prog_array_length (Martin Lau)
* added [0,2] return code check to verifier (Martin Lau)
* dropped unused buf[64] from the stack (Martin Lau)
* use PTR_TO_SOCKET for bpf_sockopt->sk (Martin Lau)
* dropped bpf_target_off from ctx rewrites (Martin Lau)
* use return code for kernel bypass (Martin Lau & Andrii Nakryiko)

Cc: Andrii Nakryiko <andriin@fb.com>
Cc: Martin Lau <kafai@fb.com>
Signed-off-by: NStanislav Fomichev <sdf@google.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>

Convert proc_dointvec_minmax_bpf_stats() into a more generic
helper, since we are going to use jump labels more often.

Note that sysctl_bpf_stats_enabled is removed, since
it is no longer needed/used.
Signed-off-by: NEric Dumazet <edumazet@google.com>
Acked-by: NAlexei Starovoitov <ast@kernel.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

If CONFIG_INET is not set, building fails:

kernel/bpf/verifier.o: In function `check_mem_access':
verifier.c: undefined reference to `bpf_xdp_sock_is_valid_access'
kernel/bpf/verifier.o: In function `convert_ctx_accesses':
verifier.c: undefined reference to `bpf_xdp_sock_convert_ctx_access'
Reported-by: NHulk Robot <hulkci@huawei.com>
Fixes: fada7fdc ("bpf: Allow bpf_map_lookup_elem() on an xskmap")
Signed-off-by: NYueHaibing <yuehaibing@huawei.com>
Acked-by: NJonathan Lemon <jonathan.lemon@gmail.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

Currently, the AF_XDP code uses a separate map in order to
determine if an xsk is bound to a queue.  Instead of doing this,
have bpf_map_lookup_elem() return a xdp_sock.

Rearrange some xdp_sock members to eliminate structure holes.

Remove selftest - will be added back in later patch.
Signed-off-by: NJonathan Lemon <jonathan.lemon@gmail.com>
Acked-by: NMartin KaFai Lau <kafai@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>

Most bpf map types doing similar checks and bytes to pages
conversion during memory allocation and charging.

Let's unify these checks by moving them into bpf_map_charge_init().
Signed-off-by: NRoman Gushchin <guro@fb.com>
Acked-by: NSong Liu <songliubraving@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>

In order to unify the existing memlock charging code with the
memcg-based memory accounting, which will be added later, let's
rework the current scheme.

Currently the following design is used:
  1) .alloc() callback optionally checks if the allocation will likely
     succeed using bpf_map_precharge_memlock()
  2) .alloc() performs actual allocations
  3) .alloc() callback calculates map cost and sets map.memory.pages
  4) map_create() calls bpf_map_init_memlock() which sets map.memory.user
     and performs actual charging; in case of failure the map is
     destroyed
  <map is in use>
  1) bpf_map_free_deferred() calls bpf_map_release_memlock(), which
     performs uncharge and releases the user
  2) .map_free() callback releases the memory

The scheme can be simplified and made more robust:
  1) .alloc() calculates map cost and calls bpf_map_charge_init()
  2) bpf_map_charge_init() sets map.memory.user and performs actual
    charge
  3) .alloc() performs actual allocations
  <map is in use>
  1) .map_free() callback releases the memory
  2) bpf_map_charge_finish() performs uncharge and releases the user

The new scheme also allows to reuse bpf_map_charge_init()/finish()
functions for memcg-based accounting. Because charges are performed
before actual allocations and uncharges after freeing the memory,
no bogus memory pressure can be created.

In cases when the map structure is not available (e.g. it's not
created yet, or is already destroyed), on-stack bpf_map_memory
structure is used. The charge can be transferred with the
bpf_map_charge_move() function.
Signed-off-by: NRoman Gushchin <guro@fb.com>
Acked-by: NSong Liu <songliubraving@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>

Group "user" and "pages" fields of bpf_map into the bpf_map_memory
structure. Later it can be extended with "memcg" and other related
information.

The main reason for a such change (beside cosmetics) is to pass
bpf_map_memory structure to charging functions before the actual
allocation of bpf_map.
Signed-off-by: NRoman Gushchin <guro@fb.com>
Acked-by: NSong Liu <songliubraving@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>

Create new macro BPF_PROG_CGROUP_INET_EGRESS_RUN_ARRAY() to be used by
__cgroup_bpf_run_filter_skb for EGRESS BPF progs so BPF programs can
request cwr for TCP packets.

Current cgroup skb programs can only return 0 or 1 (0 to drop the
packet. This macro changes the behavior so the low order bit
indicates whether the packet should be dropped (0) or not (1)
and the next bit is used for congestion notification (cn).

Hence, new allowed return values of CGROUP EGRESS BPF programs are:
  0: drop packet
  1: keep packet
  2: drop packet and call cwr
  3: keep packet and call cwr

This macro then converts it to one of NET_XMIT values or -EPERM
that has the effect of dropping the packet with no cn.
  0: NET_XMIT_SUCCESS  skb should be transmitted (no cn)
  1: NET_XMIT_DROP     skb should be dropped and cwr called
  2: NET_XMIT_CN       skb should be transmitted and cwr called
  3: -EPERM            skb should be dropped (no cn)

Note that when more than one BPF program is called, the packet is
dropped if at least one of programs requests it be dropped, and
there is cn if at least one program returns cn.
Signed-off-by: NLawrence Brakmo <brakmo@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>

Based on 1 normalized pattern(s):

  this program is free software you can redistribute it and or modify
  it under the terms of version 2 of the gnu general public license as
  published by the free software foundation

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-only

has been chosen to replace the boilerplate/reference in 107 file(s).
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: NAllison Randal <allison@lohutok.net>
Reviewed-by: NRichard Fontana <rfontana@redhat.com>
Reviewed-by: NSteve Winslow <swinslow@gmail.com>
Reviewed-by: NAlexios Zavras <alexios.zavras@intel.com>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190528171438.615055994@linutronix.deSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Drop __rcu annotations and rcu read sections from bpf_prog_array
helper functions. They are not needed since all existing callers
call those helpers from the rcu update side while holding a mutex.
This guarantees that use-after-free could not happen.

In the next patches I'll fix the callers with missing
rcu_dereference_protected to make sparse/lockdep happy, the proper
way to use these helpers is:

	struct bpf_prog_array __rcu *progs = ...;
	struct bpf_prog_array *p;

	mutex_lock(&mtx);
	p = rcu_dereference_protected(progs, lockdep_is_held(&mtx));
	bpf_prog_array_length(p);
	bpf_prog_array_copy_to_user(p, ...);
	bpf_prog_array_delete_safe(p, ...);
	bpf_prog_array_copy_info(p, ...);
	bpf_prog_array_copy(p, ...);
	bpf_prog_array_free(p);
	mutex_unlock(&mtx);

No functional changes! rcu_dereference_protected with lockdep_is_held
should catch any cases where we update prog array without a mutex
(I've looked at existing call sites and I think we hold a mutex
everywhere).

Motivation is to fix sparse warnings:
kernel/bpf/core.c:1803:9: warning: incorrect type in argument 1 (different address spaces)
kernel/bpf/core.c:1803:9:    expected struct callback_head *head
kernel/bpf/core.c:1803:9:    got struct callback_head [noderef] <asn:4> *
kernel/bpf/core.c:1877:44: warning: incorrect type in initializer (different address spaces)
kernel/bpf/core.c:1877:44:    expected struct bpf_prog_array_item *item
kernel/bpf/core.c:1877:44:    got struct bpf_prog_array_item [noderef] <asn:4> *
kernel/bpf/core.c:1901:26: warning: incorrect type in assignment (different address spaces)
kernel/bpf/core.c:1901:26:    expected struct bpf_prog_array_item *existing
kernel/bpf/core.c:1901:26:    got struct bpf_prog_array_item [noderef] <asn:4> *
kernel/bpf/core.c:1935:26: warning: incorrect type in assignment (different address spaces)
kernel/bpf/core.c:1935:26:    expected struct bpf_prog_array_item *[assigned] existing
kernel/bpf/core.c:1935:26:    got struct bpf_prog_array_item [noderef] <asn:4> *

v2:
* remove comment about potential race; that can't happen
  because all callers are in rcu-update section

Cc: Roman Gushchin <guro@fb.com>
Acked-by: NRoman Gushchin <guro@fb.com>
Signed-off-by: NStanislav Fomichev <sdf@google.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

After previous patches, verifier will mark a insn if it really needs zero
extension on dst_reg.

It is then for back-ends to decide how to use such information to eliminate
unnecessary zero extension code-gen during JIT compilation.

One approach is verifier insert explicit zero extension for those insns
that need zero extension in a generic way, JIT back-ends then do not
generate zero extension for sub-register write at default.

However, only those back-ends which do not have hardware zero extension
want this optimization. Back-ends like x86_64 and AArch64 have hardware
zero extension support that the insertion should be disabled.

This patch introduces new target hook "bpf_jit_needs_zext" which returns
false at default, meaning verifier zero extension insertion is disabled at
default. A back-end could override this hook to return true if it doesn't
have hardware support and want verifier insert zero extension explicitly.

Offload targets do not use this native target hook, instead, they could
get the optimization results using bpf_prog_offload_ops.finalize.

NOTE: arches could have diversified features, it is possible for one arch
to have hardware zero extension support for some sub-register write insns
but not for all. For example, PowerPC, SPARC have zero extended loads, but
not for alu32. So when verifier zero extension insertion enabled, these JIT
back-ends need to peephole insns to remove those zero extension inserted
for insn that actually has hardware zero extension support. The peephole
could be as simple as looking the next insn, if it is a special zero
extension insn then it is safe to eliminate it if the current insn has
hardware zero extension support.
Reviewed-by: NJakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: NJiong Wang <jiong.wang@netronome.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>

Add a callback map_lookup_elem_sys_only() that map implementations
could use over map_lookup_elem() from system call side in case the
map implementation needs to handle the latter differently than from
the BPF data path. If map_lookup_elem_sys_only() is set, this will
be preferred pick for map lookups out of user space. This hook is
used in a follow-up fix for LRU map, but once development window
opens, we can convert other map types from map_lookup_elem() (here,
the one called upon BPF_MAP_LOOKUP_ELEM cmd is meant) over to use
the callback to simplify and clean up the latter.
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Acked-by: NMartin KaFai Lau <kafai@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>

After allowing a bpf prog to
- directly read the skb->sk ptr
- get the fullsock bpf_sock by "bpf_sk_fullsock()"
- get the bpf_tcp_sock by "bpf_tcp_sock()"
- get the listener sock by "bpf_get_listener_sock()"
- avoid duplicating the fields of "(bpf_)sock" and "(bpf_)tcp_sock"
  into different bpf running context.

this patch is another effort to make bpf's network programming
more intuitive to do (together with memory and performance benefit).

When bpf prog needs to store data for a sk, the current practice is to
define a map with the usual 4-tuples (src/dst ip/port) as the key.
If multiple bpf progs require to store different sk data, multiple maps
have to be defined.  Hence, wasting memory to store the duplicated
keys (i.e. 4 tuples here) in each of the bpf map.
[ The smallest key could be the sk pointer itself which requires
  some enhancement in the verifier and it is a separate topic. ]

Also, the bpf prog needs to clean up the elem when sk is freed.
Otherwise, the bpf map will become full and un-usable quickly.
The sk-free tracking currently could be done during sk state
transition (e.g. BPF_SOCK_OPS_STATE_CB).

The size of the map needs to be predefined which then usually ended-up
with an over-provisioned map in production.  Even the map was re-sizable,
while the sk naturally come and go away already, this potential re-size
operation is arguably redundant if the data can be directly connected
to the sk itself instead of proxy-ing through a bpf map.

This patch introduces sk->sk_bpf_storage to provide local storage space
at sk for bpf prog to use.  The space will be allocated when the first bpf
prog has created data for this particular sk.

The design optimizes the bpf prog's lookup (and then optionally followed by
an inline update).  bpf_spin_lock should be used if the inline update needs
to be protected.

BPF_MAP_TYPE_SK_STORAGE:
-----------------------
To define a bpf "sk-local-storage", a BPF_MAP_TYPE_SK_STORAGE map (new in
this patch) needs to be created.  Multiple BPF_MAP_TYPE_SK_STORAGE maps can
be created to fit different bpf progs' needs.  The map enforces
BTF to allow printing the sk-local-storage during a system-wise
sk dump (e.g. "ss -ta") in the future.

The purpose of a BPF_MAP_TYPE_SK_STORAGE map is not for lookup/update/delete
a "sk-local-storage" data from a particular sk.
Think of the map as a meta-data (or "type") of a "sk-local-storage".  This
particular "type" of "sk-local-storage" data can then be stored in any sk.

The main purposes of this map are mostly:
1. Define the size of a "sk-local-storage" type.
2. Provide a similar syscall userspace API as the map (e.g. lookup/update,
   map-id, map-btf...etc.)
3. Keep track of all sk's storages of this "type" and clean them up
   when the map is freed.

sk->sk_bpf_storage:
------------------
The main lookup/update/delete is done on sk->sk_bpf_storage (which
is a "struct bpf_sk_storage").  When doing a lookup,
the "map" pointer is now used as the "key" to search on the
sk_storage->list.  The "map" pointer is actually serving
as the "type" of the "sk-local-storage" that is being
requested.

To allow very fast lookup, it should be as fast as looking up an
array at a stable-offset.  At the same time, it is not ideal to
set a hard limit on the number of sk-local-storage "type" that the
system can have.  Hence, this patch takes a cache approach.
The last search result from sk_storage->list is cached in
sk_storage->cache[] which is a stable sized array.  Each
"sk-local-storage" type has a stable offset to the cache[] array.
In the future, a map's flag could be introduced to do cache
opt-out/enforcement if it became necessary.

The cache size is 16 (i.e. 16 types of "sk-local-storage").
Programs can share map.  On the program side, having a few bpf_progs
running in the networking hotpath is already a lot.  The bpf_prog
should have already consolidated the existing sock-key-ed map usage
to minimize the map lookup penalty.  16 has enough runway to grow.

All sk-local-storage data will be removed from sk->sk_bpf_storage
during sk destruction.

bpf_sk_storage_get() and bpf_sk_storage_delete():
------------------------------------------------
Instead of using bpf_map_(lookup|update|delete)_elem(),
the bpf prog needs to use the new helper bpf_sk_storage_get() and
bpf_sk_storage_delete().  The verifier can then enforce the
ARG_PTR_TO_SOCKET argument.  The bpf_sk_storage_get() also allows to
"create" new elem if one does not exist in the sk.  It is done by
the new BPF_SK_STORAGE_GET_F_CREATE flag.  An optional value can also be
provided as the initial value during BPF_SK_STORAGE_GET_F_CREATE.
The BPF_MAP_TYPE_SK_STORAGE also supports bpf_spin_lock.  Together,
it has eliminated the potential use cases for an equivalent
bpf_map_update_elem() API (for bpf_prog) in this patch.

Misc notes:
----------
1. map_get_next_key is not supported.  From the userspace syscall
   perspective,  the map has the socket fd as the key while the map
   can be shared by pinned-file or map-id.

   Since btf is enforced, the existing "ss" could be enhanced to pretty
   print the local-storage.

   Supporting a kernel defined btf with 4 tuples as the return key could
   be explored later also.

2. The sk->sk_lock cannot be acquired.  Atomic operations is used instead.
   e.g. cmpxchg is done on the sk->sk_bpf_storage ptr.
   Please refer to the source code comments for the details in
   synchronization cases and considerations.

3. The mem is charged to the sk->sk_omem_alloc as the sk filter does.

Benchmark:
---------
Here is the benchmark data collected by turning on
the "kernel.bpf_stats_enabled" sysctl.
Two bpf progs are tested:

One bpf prog with the usual bpf hashmap (max_entries = 8192) with the
sk ptr as the key. (verifier is modified to support sk ptr as the key
That should have shortened the key lookup time.)

Another bpf prog is with the new BPF_MAP_TYPE_SK_STORAGE.

Both are storing a "u32 cnt", do a lookup on "egress_skb/cgroup" for
each egress skb and then bump the cnt.  netperf is used to drive
data with 4096 connected UDP sockets.

BPF_MAP_TYPE_HASH with a modifier verifier (152ns per bpf run)
27: cgroup_skb  name egress_sk_map  tag 74f56e832918070b run_time_ns 58280107540 run_cnt 381347633
    loaded_at 2019-04-15T13:46:39-0700  uid 0
    xlated 344B  jited 258B  memlock 4096B  map_ids 16
    btf_id 5

BPF_MAP_TYPE_SK_STORAGE in this patch (66ns per bpf run)
30: cgroup_skb  name egress_sk_stora  tag d4aa70984cc7bbf6 run_time_ns 25617093319 run_cnt 390989739
    loaded_at 2019-04-15T13:47:54-0700  uid 0
    xlated 168B  jited 156B  memlock 4096B  map_ids 17
    btf_id 6

Here is a high-level picture on how are the objects organized:

       sk
    ┌──────┐
    │      │
    │      │
    │      │
    │*sk_bpf_storage─────▶ bpf_sk_storage
    └──────┘                 ┌───────┐
                 ┌───────────┤ list  │
                 │           │       │
                 │           │       │
                 │           │       │
                 │           └───────┘
                 │
                 │     elem
                 │  ┌────────┐
                 ├─▶│ snode  │
                 │  ├────────┤
                 │  │  data  │          bpf_map
                 │  ├────────┤        ┌─────────┐
                 │  │map_node│◀─┬─────┤  list   │
                 │  └────────┘  │     │         │
                 │              │     │         │
                 │     elem     │     │         │
                 │  ┌────────┐  │     └─────────┘
                 └─▶│ snode  │  │
                    ├────────┤  │
   bpf_map          │  data  │  │
 ┌─────────┐        ├────────┤  │
 │  list   ├───────▶│map_node│  │
 │         │        └────────┘  │
 │         │                    │
 │         │           elem     │
 └─────────┘        ┌────────┐  │
                 ┌─▶│ snode  │  │
                 │  ├────────┤  │
                 │  │  data  │  │
                 │  ├────────┤  │
                 │  │map_node│◀─┘
                 │  └────────┘
                 │
                 │
                 │          ┌───────┐
     sk          └──────────│ list  │
  ┌──────┐                  │       │
  │      │                  │       │
  │      │                  │       │
  │      │                  └───────┘
  │*sk_bpf_storage───────▶bpf_sk_storage
  └──────┘
Signed-off-by: NMartin KaFai Lau <kafai@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>

This is an opt-in interface that allows a tracepoint to provide a safe
buffer that can be written from a BPF_PROG_TYPE_RAW_TRACEPOINT program.
The size of the buffer must be a compile-time constant, and is checked
before allowing a BPF program to attach to a tracepoint that uses this
feature.

The pointer to this buffer will be the first argument of tracepoints
that opt in; the pointer is valid and can be bpf_probe_read() by both
BPF_PROG_TYPE_RAW_TRACEPOINT and BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE
programs that attach to such a tracepoint, but the buffer to which it
points may only be written by the latter.
Signed-off-by: NMatt Mullins <mmullins@fb.com>
Acked-by: NYonghong Song <yhs@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>

Unless the very next line is schedule(), or implies it, one must not use
preempt_enable_no_resched(). It can cause a preemption to go missing and
thereby cause arbitrary delays, breaking the PREEMPT=y invariant.

Cc: Roman Gushchin <guro@fb.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>

Add bpf_strtol and bpf_strtoul to convert a string to long and unsigned
long correspondingly. It's similar to user space strtol(3) and
strtoul(3) with a few changes to the API:

* instead of NUL-terminated C string the helpers expect buffer and
  buffer length;

* resulting long or unsigned long is returned in a separate
  result-argument;

* return value is used to indicate success or failure, on success number
  of consumed bytes is returned that can be used to identify position to
  read next if the buffer is expected to contain multiple integers;

* instead of *base* argument, *flags* is used that provides base in 5
  LSB, other bits are reserved for future use;

* number of supported bases is limited.

Documentation for the new helpers is provided in bpf.h UAPI.

The helpers are made available to BPF_PROG_TYPE_CGROUP_SYSCTL programs to
be able to convert string input to e.g. "ulongvec" output.

E.g. "net/ipv4/tcp_mem" consists of three ulong integers. They can be
parsed by calling to bpf_strtoul three times.

Implementation notes:

Implementation includes "../../lib/kstrtox.h" to reuse integer parsing
functions. It's done exactly same way as fs/proc/base.c already does.

Unfortunately existing kstrtoX function can't be used directly since
they fail if any invalid character is present right after integer in the
string. Existing simple_strtoX functions can't be used either since
they're obsolete and don't handle overflow properly.
Signed-off-by: NAndrey Ignatov <rdna@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>

Currently the way to pass result from BPF helper to BPF program is to
provide memory area defined by pointer and size: func(void *, size_t).

It works great for generic use-case, but for simple types, such as int,
it's overkill and consumes two arguments when it could use just one.

Introduce new argument types ARG_PTR_TO_INT and ARG_PTR_TO_LONG to be
able to pass result from helper to program via pointer to int and long
correspondingly: func(int *) or func(long *).

New argument types are similar to ARG_PTR_TO_MEM with the following
differences:
* they don't require corresponding ARG_CONST_SIZE argument, predefined
  access sizes are used instead (32bit for int, 64bit for long);
* it's possible to use more than one such an argument in a helper;
* provided pointers have to be aligned.

It's easy to introduce similar ARG_PTR_TO_CHAR and ARG_PTR_TO_SHORT
argument types. It's not done due to lack of use-case though.
Signed-off-by: NAndrey Ignatov <rdna@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>

Commit b0b9395d ("bpf: support input __sk_buff context in
BPF_PROG_TEST_RUN") started using bpf_check_uarg_tail_zero in
BPF_PROG_TEST_RUN. However, bpf_check_uarg_tail_zero is not defined
for !CONFIG_BPF_SYSCALL:

net/bpf/test_run.c: In function ‘bpf_ctx_init’:
net/bpf/test_run.c:142:9: error: implicit declaration of function ‘bpf_check_uarg_tail_zero’ [-Werror=implicit-function-declaration]
   err = bpf_check_uarg_tail_zero(data_in, max_size, size);
         ^~~~~~~~~~~~~~~~~~~~~~~~

Let's not build net/bpf/test_run.c when CONFIG_BPF_SYSCALL is not set.
Reported-by: Nkbuild test robot <lkp@intel.com>
Fixes: b0b9395d ("bpf: support input __sk_buff context in BPF_PROG_TEST_RUN")
Signed-off-by: NStanislav Fomichev <sdf@google.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

This patch adds a new BPF_MAP_FREEZE command which allows to
"freeze" the map globally as read-only / immutable from syscall
side.

Map permission handling has been refactored into map_get_sys_perms()
and drops FMODE_CAN_WRITE in case of locked map. Main use case is
to allow for setting up .rodata sections from the BPF ELF which
are loaded into the kernel, meaning BPF loader first allocates
map, sets up map value by copying .rodata section into it and once
complete, it calls BPF_MAP_FREEZE on the map fd to prevent further
modifications.

Right now BPF_MAP_FREEZE only takes map fd as argument while remaining
bpf_attr members are required to be zero. I didn't add write-only
locking here as counterpart since I don't have a concrete use-case
for it on my side, and I think it makes probably more sense to wait
once there is actually one. In that case bpf_attr can be extended
as usual with a flag field and/or others where flag 0 means that
we lock the map read-only hence this doesn't prevent to add further
extensions to BPF_MAP_FREEZE upon need.

A map creation flag like BPF_F_WRONCE was not considered for couple
of reasons: i) in case of a generic implementation, a map can consist
of more than just one element, thus there could be multiple map
updates needed to set the map into a state where it can then be
made immutable, ii) WRONCE indicates exact one-time write before
it is then set immutable. A generic implementation would set a bit
atomically on map update entry (if unset), indicating that every
subsequent update from then onwards will need to bail out there.
However, map updates can fail, so upon failure that flag would need
to be unset again and the update attempt would need to be repeated
for it to be eventually made immutable. While this can be made
race-free, this approach feels less clean and in combination with
reason i), it's not generic enough. A dedicated BPF_MAP_FREEZE
command directly sets the flag and caller has the guarantee that
map is immutable from syscall side upon successful return for any
future syscall invocations that would alter the map state, which
is also more intuitive from an API point of view. A command name
such as BPF_MAP_LOCK has been avoided as it's too close with BPF
map spin locks (which already has BPF_F_LOCK flag). BPF_MAP_FREEZE
is so far only enabled for privileged users.
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Acked-by: NMartin KaFai Lau <kafai@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>

This work adds two new map creation flags BPF_F_RDONLY_PROG
and BPF_F_WRONLY_PROG in order to allow for read-only or
write-only BPF maps from a BPF program side.

Today we have BPF_F_RDONLY and BPF_F_WRONLY, but this only
applies to system call side, meaning the BPF program has full
read/write access to the map as usual while bpf(2) calls with
map fd can either only read or write into the map depending
on the flags. BPF_F_RDONLY_PROG and BPF_F_WRONLY_PROG allows
for the exact opposite such that verifier is going to reject
program loads if write into a read-only map or a read into a
write-only map is detected. For read-only map case also some
helpers are forbidden for programs that would alter the map
state such as map deletion, update, etc. As opposed to the two
BPF_F_RDONLY / BPF_F_WRONLY flags, BPF_F_RDONLY_PROG as well
as BPF_F_WRONLY_PROG really do correspond to the map lifetime.

We've enabled this generic map extension to various non-special
maps holding normal user data: array, hash, lru, lpm, local
storage, queue and stack. Further generic map types could be
followed up in future depending on use-case. Main use case
here is to forbid writes into .rodata map values from verifier
side.
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Acked-by: NMartin KaFai Lau <kafai@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>

This generic extension to BPF maps allows for directly loading
an address residing inside a BPF map value as a single BPF
ldimm64 instruction!

The idea is similar to what BPF_PSEUDO_MAP_FD does today, which
is a special src_reg flag for ldimm64 instruction that indicates
that inside the first part of the double insns's imm field is a
file descriptor which the verifier then replaces as a full 64bit
address of the map into both imm parts. For the newly added
BPF_PSEUDO_MAP_VALUE src_reg flag, the idea is the following:
the first part of the double insns's imm field is again a file
descriptor corresponding to the map, and the second part of the
imm field is an offset into the value. The verifier will then
replace both imm parts with an address that points into the BPF
map value at the given value offset for maps that support this
operation. Currently supported is array map with single entry.
It is possible to support more than just single map element by
reusing both 16bit off fields of the insns as a map index, so
full array map lookup could be expressed that way. It hasn't
been implemented here due to lack of concrete use case, but
could easily be done so in future in a compatible way, since
both off fields right now have to be 0 and would correctly
denote a map index 0.

The BPF_PSEUDO_MAP_VALUE is a distinct flag as otherwise with
BPF_PSEUDO_MAP_FD we could not differ offset 0 between load of
map pointer versus load of map's value at offset 0, and changing
BPF_PSEUDO_MAP_FD's encoding into off by one to differ between
regular map pointer and map value pointer would add unnecessary
complexity and increases barrier for debugability thus less
suitable. Using the second part of the imm field as an offset
into the value does /not/ come with limitations since maximum
possible value size is in u32 universe anyway.

This optimization allows for efficiently retrieving an address
to a map value memory area without having to issue a helper call
which needs to prepare registers according to calling convention,
etc, without needing the extra NULL test, and without having to
add the offset in an additional instruction to the value base
pointer. The verifier then treats the destination register as
PTR_TO_MAP_VALUE with constant reg->off from the user passed
offset from the second imm field, and guarantees that this is
within bounds of the map value. Any subsequent operations are
normally treated as typical map value handling without anything
extra needed from verification side.

The two map operations for direct value access have been added to
array map for now. In future other types could be supported as
well depending on the use case. The main use case for this commit
is to allow for BPF loader support for global variables that
reside in .data/.rodata/.bss sections such that we can directly
load the address of them with minimal additional infrastructure
required. Loader support has been added in subsequent commits for
libbpf library.
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>

Large verifier speed improvements allow to increase
verifier complexity limit.
Now regardless of the program composition and its size it takes
little time for the verifier to hit insn_processed limit.
On typical x86 machine non-debug kernel processes 1M instructions
in 1/10 of a second.
(before these speed improvements specially crafted programs
could be hitting multi-second verification times)
Full kasan kernel with debug takes ~1 second for the same 1M insns.
Hence bump the BPF_COMPLEXITY_LIMIT_INSNS limit to 1M.
Also increase the number of instructions per program
from 4k to internal BPF_COMPLEXITY_LIMIT_INSNS limit.
4k limit was confusing to users, since small programs with hundreds
of insns could be hitting BPF_COMPLEXITY_LIMIT_INSNS limit.
Sometimes adding more insns and bpf_trace_printk debug statements
would make the verifier accept the program while removing
code would make the verifier reject it.
Some user space application started to add #define MAX_FOO to
their programs and do:
  MAX_FOO=100;
again:
  compile with MAX_FOO;
  try to load;
  if (fails_to_load) { reduce MAX_FOO; goto again; }
to be able to fit maximum amount of processing into single program.
Other users artificially split their single program into a set of programs
and use all 32 iterations of tail_calls to increase compute limits.
And the most advanced folks used unlimited tc-bpf filter list
to execute many bpf programs.
Essentially the users managed to workaround 4k insn limit.
This patch removes the limit for root programs from uapi.
BPF_COMPLEXITY_LIMIT_INSNS is the kernel internal limit
and success to load the program no longer depends on program size,
but on 'smartness' of the verifier only.
The verifier will continue to get smarter with every kernel release.
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

It's currently not possible to access timewait or request sockets
from eBPF, since there is no way to return a PTR_TO_SOCK_COMMON
from a helper. Introduce RET_PTR_TO_SOCK_COMMON to enable this
behaviour.
Signed-off-by: NLorenz Bauer <lmb@cloudflare.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>

Lorenz Bauer [thanks!] reported that a ptr returned by bpf_tcp_sock(sk)
can still be accessed after bpf_sk_release(sk).
Both bpf_tcp_sock() and bpf_sk_fullsock() have the same issue.
This patch addresses them together.

A simple reproducer looks like this:

	sk = bpf_sk_lookup_tcp();
	/* if (!sk) ... */
	tp = bpf_tcp_sock(sk);
	/* if (!tp) ... */
	bpf_sk_release(sk);
	snd_cwnd = tp->snd_cwnd; /* oops! The verifier does not complain. */

The problem is the verifier did not scrub the register's states of
the tcp_sock ptr (tp) after bpf_sk_release(sk).

[ Note that when calling bpf_tcp_sock(sk), the sk is not always
  refcount-acquired. e.g. bpf_tcp_sock(skb->sk). The verifier works
  fine for this case. ]

Currently, the verifier does not track if a helper's return ptr (in REG_0)
is "carry"-ing one of its argument's refcount status. To carry this info,
the reg1->id needs to be stored in reg0.

One approach was tried, like "reg0->id = reg1->id", when calling
"bpf_tcp_sock()".  The main idea was to avoid adding another "ref_obj_id"
for the same reg.  However, overlapping the NULL marking and ref
tracking purpose in one "id" does not work well:

	ref_sk = bpf_sk_lookup_tcp();
	fullsock = bpf_sk_fullsock(ref_sk);
	tp = bpf_tcp_sock(ref_sk);
	if (!fullsock) {
	     bpf_sk_release(ref_sk);
	     return 0;
	}
	/* fullsock_reg->id is marked for NOT-NULL.
	 * Same for tp_reg->id because they have the same id.
	 */

	/* oops. verifier did not complain about the missing !tp check */
	snd_cwnd = tp->snd_cwnd;

Hence, a new "ref_obj_id" is needed in "struct bpf_reg_state".
With a new ref_obj_id, when bpf_sk_release(sk) is called, the verifier can
scrub all reg states which has a ref_obj_id match.  It is done with the
changes in release_reg_references() in this patch.

While fixing it, sk_to_full_sk() is removed from bpf_tcp_sock() and
bpf_sk_fullsock() to avoid these helpers from returning
another ptr. It will make bpf_sk_release(tp) possible:

	sk = bpf_sk_lookup_tcp();
	/* if (!sk) ... */
	tp = bpf_tcp_sock(sk);
	/* if (!tp) ... */
	bpf_sk_release(tp);

A separate helper "bpf_get_listener_sock()" will be added in a later
patch to do sk_to_full_sk().

Misc change notes:
- To allow bpf_sk_release(tp), the arg of bpf_sk_release() is changed
  from ARG_PTR_TO_SOCKET to ARG_PTR_TO_SOCK_COMMON.  ARG_PTR_TO_SOCKET
  is removed from bpf.h since no helper is using it.

- arg_type_is_refcounted() is renamed to arg_type_may_be_refcounted()
  because ARG_PTR_TO_SOCK_COMMON is the only one and skb->sk is not
  refcounted.  All bpf_sk_release(), bpf_sk_fullsock() and bpf_tcp_sock()
  take ARG_PTR_TO_SOCK_COMMON.

- check_refcount_ok() ensures is_acquire_function() cannot take
  arg_type_may_be_refcounted() as its argument.

- The check_func_arg() can only allow one refcount-ed arg.  It is
  guaranteed by check_refcount_ok() which ensures at most one arg can be
  refcounted.  Hence, it is a verifier internal error if >1 refcount arg
  found in check_func_arg().

- In release_reference(), release_reference_state() is called
  first to ensure a match on "reg->ref_obj_id" can be found before
  scrubbing the reg states with release_reg_references().

- reg_is_refcounted() is no longer needed.
  1. In mark_ptr_or_null_regs(), its usage is replaced by
     "ref_obj_id && ref_obj_id == id" because,
     when is_null == true, release_reference_state() should only be
     called on the ref_obj_id obtained by a acquire helper (i.e.
     is_acquire_function() == true).  Otherwise, the following
     would happen:

	sk = bpf_sk_lookup_tcp();
	/* if (!sk) { ... } */
	fullsock = bpf_sk_fullsock(sk);
	if (!fullsock) {
		/*
		 * release_reference_state(fullsock_reg->ref_obj_id)
		 * where fullsock_reg->ref_obj_id == sk_reg->ref_obj_id.
		 *
		 * Hence, the following bpf_sk_release(sk) will fail
		 * because the ref state has already been released in the
		 * earlier release_reference_state(fullsock_reg->ref_obj_id).
		 */
		bpf_sk_release(sk);
	}

  2. In release_reg_references(), the current reg_is_refcounted() call
     is unnecessary because the id check is enough.

- The type_is_refcounted() and type_is_refcounted_or_null()
  are no longer needed also because reg_is_refcounted() is removed.

Fixes: 655a51e5 ("bpf: Add struct bpf_tcp_sock and BPF_FUNC_tcp_sock")
Reported-by: NLorenz Bauer <lmb@cloudflare.com>
Signed-off-by: NMartin KaFai Lau <kafai@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>

JITed BPF programs are indistinguishable from kernel functions, but unlike
kernel code BPF code can be changed often.
Typical approach of "perf record" + "perf report" profiling and tuning of
kernel code works just as well for BPF programs, but kernel code doesn't
need to be monitored whereas BPF programs do.
Users load and run large amount of BPF programs.
These BPF stats allow tools monitor the usage of BPF on the server.
The monitoring tools will turn sysctl kernel.bpf_stats_enabled
on and off for few seconds to sample average cost of the programs.
Aggregated data over hours and days will provide an insight into cost of BPF
and alarms can trigger in case given program suddenly gets more expensive.

The cost of two sched_clock() per program invocation adds ~20 nsec.
Fast BPF progs (like selftests/bpf/progs/test_pkt_access.c) will slow down
from ~10 nsec to ~30 nsec.
static_key minimizes the cost of the stats collection.
There is no measurable difference before/after this patch
with kernel.bpf_stats_enabled=0
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

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: NJakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: NQuentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

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: NAlexei Starovoitov <ast@kernel.org>
Signed-off-by: NMartin KaFai Lau <kafai@fb.com>
Signed-off-by: NAlexei 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: NAlexei Starovoitov <ast@kernel.org>
Signed-off-by: NMartin KaFai Lau <kafai@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>