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: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20191016032505.2089704-11-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: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20191016032505.2089704-7-ast@kernel.org

If in-kernel BTF exists parse it and prepare 'struct btf *btf_vmlinux'
for further use by the verifier.
In-kernel BTF is trusted just like kallsyms and other build artifacts
embedded into vmlinux.
Yet run this BTF image through BTF verifier to make sure
that it is valid and it wasn't mangled during the build.
If in-kernel BTF is incorrect it means either gcc or pahole or kernel
are buggy. In such case disallow loading BPF programs.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20191016032505.2089704-4-ast@kernel.org

There is a statement that is indented one level too deeply, remove
the extraneous tab.
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20190925093835.19515-1-colin.king@canonical.com

vmlinux BTF has enums that are 8 byte and 1 byte in size.
2 byte enum is a valid construct as well.
Fix BTF enum verification to accept those sizes.

Fixes: 69b693f0 ("bpf: btf: Introduce BPF Type Format (BTF)")
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

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: Quentin Monnet <quentin.monnet@netronome.com>
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

Implement the show_fdinfo hook for BTF FDs file operations, and make it
print the id of the BTF object. This allows for a quick retrieval of the
BTF id from its FD; or it can help understanding what type of object
(BTF) the file descriptor points to.

v2:
- Do not expose data_size, only btf_id, in FD info.
Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

BTF verifier has a size resolution bug which in some circumstances leads to
invalid size resolution for, e.g., TYPEDEF modifier.  This happens if we have
[1] PTR -> [2] TYPEDEF -> [3] ARRAY, in which case due to being in pointer
context ARRAY size won't be resolved (because for pointer it doesn't matter, so
it's a sink in pointer context), but it will be permanently remembered as zero
for TYPEDEF and TYPEDEF will be marked as RESOLVED. Eventually ARRAY size will
be resolved correctly, but TYPEDEF resolved_size won't be updated anymore.
This, subsequently, will lead to erroneous map creation failure, if that
TYPEDEF is specified as either key or value, as key_size/value_size won't
correspond to resolved size of TYPEDEF (kernel will believe it's zero).

Note, that if BTF was ordered as [1] ARRAY <- [2] TYPEDEF <- [3] PTR, this
won't be a problem, as by the time we get to TYPEDEF, ARRAY's size is already
calculated and stored.

This bug manifests itself in rejecting BTF-defined maps that use array
typedef as a value type:

typedef int array_t[16];

struct {
    __uint(type, BPF_MAP_TYPE_ARRAY);
    __type(value, array_t); /* i.e., array_t *value; */
} test_map SEC(".maps");

The fix consists on not relying on modifier's resolved_size and instead using
modifier's resolved_id (type ID for "concrete" type to which modifier
eventually resolves) and doing size determination for that resolved type. This
allow to preserve existing "early DFS termination" logic for PTR or
STRUCT_OR_ARRAY contexts, but still do correct size determination for modifier
types.

Fixes: eb3f595d ("bpf: btf: Validate type reference")
Cc: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

Commit 1dc92851 ("bpf: kernel side support for BTF Var and DataSec")
added invocations of btf_type_is_resolve_source_only before
btf_type_nosize_or_null which checks for the NULL pointer.
Swap the order of btf_type_nosize_or_null and
btf_type_is_resolve_source_only to make sure the do the NULL pointer
check first.

Fixes: 1dc92851 ("bpf: kernel side support for BTF Var and DataSec")
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

Given we'll be reusing BPF array maps for global data/bss/rodata
sections, we need a way to associate BTF DataSec type as its map
value type. In usual cases we have this ugly BPF_ANNOTATE_KV_PAIR()
macro hack e.g. via 38d5d3b3 ("bpf: Introduce BPF_ANNOTATE_KV_PAIR")
to get initial map to type association going. While more use cases
for it are discouraged, this also won't work for global data since
the use of array map is a BPF loader detail and therefore unknown
at compilation time. For array maps with just a single entry we make
an exception in terms of BTF in that key type is declared optional
if value type is of DataSec type. The latter LLVM is guaranteed to
emit and it also aligns with how we regard global data maps as just
a plain buffer area reusing existing map facilities for allowing
things like introspection with existing tools.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

This work adds kernel-side verification, logging and seq_show dumping
of BTF Var and DataSec kinds which are emitted with latest LLVM. The
following constraints apply:

BTF Var must have:

- Its kind_flag is 0
- Its vlen is 0
- Must point to a valid type
- Type must not resolve to a forward type
- Size of underlying type must be > 0
- Must have a valid name
- Can only be a source type, not sink or intermediate one
- Name may include dots (e.g. in case of static variables
  inside functions)
- Cannot be a member of a struct/union
- Linkage so far can either only be static or global/allocated

BTF DataSec must have:

- Its kind_flag is 0
- Its vlen cannot be 0
- Its size cannot be 0
- Must have a valid name
- Can only be a source type, not sink or intermediate one
- Name may include dots (e.g. to represent .bss, .data, .rodata etc)
- Cannot be a member of a struct/union
- Inner btf_var_secinfo array with {type,offset,size} triple
  must be sorted by offset in ascending order
- Type must always point to BTF Var
- BTF resolved size of Var must be <= size provided by triple
- DataSec size must be >= sum of triple sizes (thus holes
  are allowed)

btf_var_resolve(), btf_ptr_resolve() and btf_modifier_resolve()
are on a high level quite similar but each come with slight,
subtle differences. They could potentially be a bit refactored
in future which hasn't been done here to ease review.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

Introduce 'struct bpf_spin_lock' and bpf_spin_lock/unlock() helpers to let
bpf program serialize access to other variables.

Example:
struct hash_elem {
    int cnt;
    struct bpf_spin_lock lock;
};
struct hash_elem * val = bpf_map_lookup_elem(&hash_map, &key);
if (val) {
    bpf_spin_lock(&val->lock);
    val->cnt++;
    bpf_spin_unlock(&val->lock);
}

Restrictions and safety checks:
- bpf_spin_lock is only allowed inside HASH and ARRAY maps.
- BTF description of the map is mandatory for safety analysis.
- bpf program can take one bpf_spin_lock at a time, since two or more can
  cause dead locks.
- only one 'struct bpf_spin_lock' is allowed per map element.
  It drastically simplifies implementation yet allows bpf program to use
  any number of bpf_spin_locks.
- when bpf_spin_lock is taken the calls (either bpf2bpf or helpers) are not allowed.
- bpf program must bpf_spin_unlock() before return.
- bpf program can access 'struct bpf_spin_lock' only via
  bpf_spin_lock()/bpf_spin_unlock() helpers.
- load/store into 'struct bpf_spin_lock lock;' field is not allowed.
- to use bpf_spin_lock() helper the BTF description of map value must be
  a struct and have 'struct bpf_spin_lock anyname;' field at the top level.
  Nested lock inside another struct is not allowed.
- syscall map_lookup doesn't copy bpf_spin_lock field to user space.
- syscall map_update and program map_update do not update bpf_spin_lock field.
- bpf_spin_lock cannot be on the stack or inside networking packet.
  bpf_spin_lock can only be inside HASH or ARRAY map value.
- bpf_spin_lock is available to root only and to all program types.
- bpf_spin_lock is not allowed in inner maps of map-in-map.
- ld_abs is not allowed inside spin_lock-ed region.
- tracing progs and socket filter progs cannot use bpf_spin_lock due to
  insufficient preemption checks

Implementation details:
- cgroup-bpf class of programs can nest with xdp/tc programs.
  Hence bpf_spin_lock is equivalent to spin_lock_irqsave.
  Other solutions to avoid nested bpf_spin_lock are possible.
  Like making sure that all networking progs run with softirq disabled.
  spin_lock_irqsave is the simplest and doesn't add overhead to the
  programs that don't use it.
- arch_spinlock_t is used when its implemented as queued_spin_lock
- archs can force their own arch_spinlock_t
- on architectures where queued_spin_lock is not available and
  sizeof(arch_spinlock_t) != sizeof(__u32) trivial lock is used.
- presence of bpf_spin_lock inside map value could have been indicated via
  extra flag during map_create, but specifying it via BTF is cleaner.
  It provides introspection for map key/value and reduces user mistakes.

Next steps:
- allow bpf_spin_lock in other map types (like cgroup local storage)
- introduce BPF_F_LOCK flag for bpf_map_update() syscall and helper
  to request kernel to grab bpf_spin_lock before rewriting the value.
  That will serialize access to map elements.
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

Current implementation does not allow typedef func_proto.
But it is actually allowed.
  -bash-4.4$ cat t.c
  typedef int (f) (int);
  f *g;
  -bash-4.4$ clang -O2 -g -c -target bpf t.c -Xclang -target-feature -Xclang +dwarfris
  -bash-4.4$ pahole -JV t.o
  File t.o:
  [1] PTR (anon) type_id=2
  [2] TYPEDEF f type_id=3
  [3] FUNC_PROTO (anon) return=4 args=(4 (anon))
  [4] INT int size=4 bit_offset=0 nr_bits=32 encoding=SIGNED
  -bash-4.4$

This patch related btf verifier to allow such (typedef func_proto)
patterns.

Fixes: 2667a262 ("bpf: btf: Add BTF_KIND_FUNC and BTF_KIND_FUNC_PROTO")
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

Initially in commit 69b693f0 ("bpf: btf: Introduce BPF Type Format
(BTF)") the function 'btf_name_offset_valid' was introduced as static
function it was later on changed to a non-static one, and then finally
in commit 23127b33 ("bpf: Create a new btf_name_by_offset() for
non type name use case") the function prototype was removed.

Revert back to original implementation and make the function static.
Remove warning triggered with W=1:

  kernel/bpf/btf.c:470:6: warning: no previous prototype for 'btf_name_offset_valid' [-Wmissing-prototypes]

Fixes: 23127b33 ("bpf: Create a new btf_name_by_offset() for non type name use case")
Signed-off-by: Mathieu Malaterre <malat@debian.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

Currently, btf only supports up to 64-bit integer.
On the other hand, 128bit support for gcc and clang
has existed for a long time. For example, both gcc 4.8
and llvm 3.7 supports types "__int128" and
"unsigned __int128" for virtually all 64bit architectures
including bpf.

The requirement for __int128 support comes from two areas:
  . bpf program may use __int128. For example, some bcc tools
    (https://github.com/iovisor/bcc/tree/master/tools),
    mostly tcp v6 related, tcpstates.py, tcpaccept.py, etc.,
    are using __int128 to represent the ipv6 addresses.
  . linux itself is using __int128 types. Hence supporting
    __int128 type in BTF is required for vmlinux BTF,
    which will be used by "compile once and run everywhere"
    and other projects.

For 128bit integer, instead of base-10, hex numbers are pretty
printed out as large decimal number is hard to decipher, e.g.,
for ipv6 addresses.
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

Commit 9d5f9f70 ("bpf: btf: fix struct/union/fwd types
with kind_flag") introduced kind_flag and used bitfield_size
in the btf_member to directly pretty print member values.

The commit contained a bug where the incorrect parameters could be
passed to function btf_bitfield_seq_show(). The bits_offset
parameter in the function expects a value less than 8.
Instead, the member offset in the structure is passed.

The below is btf_bitfield_seq_show() func signature:
  void btf_bitfield_seq_show(void *data, u8 bits_offset,
                             u8 nr_bits, struct seq_file *m)
both bits_offset and nr_bits are u8 type. If the bitfield
member offset is greater than 256, incorrect value will
be printed.

This patch fixed the issue by calculating correct proper
data offset and bits_offset similar to non kind_flag case.

Fixes: 9d5f9f70 ("bpf: btf: fix struct/union/fwd types with kind_flag")
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

Current btf internal verbose logger logs fwd type as
  [2] FWD A type_id=0
where A is the type name.

Commit 9d5f9f70 ("bpf: btf: fix struct/union/fwd types
with kind_flag") introduced kind_flag which can be used
to distinguish whether a forward type is a struct or
union.

Also, "type_id=0" does not carry any meaningful
information for fwd type as btf_type.type = 0 is simply
enforced during btf verification and is not used
anywhere else.

This commit changed the log to
  [2] FWD A struct
if kind_flag = 0, or
  [2] FWD A union
if kind_flag = 1.
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

Commit 970289fc0a83 ("bpf: add bpffs pretty print for cgroup
local storage maps") added bpffs pretty print for cgroup
local storage maps. The commit worked for struct without kind_flag
set.

This patch refactored and made pretty print also work
with kind_flag set for the struct.
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

This patch fixed two issues with BTF. One is related to
struct/union bitfield encoding and the other is related to
forward type.

Issue #1 and solution:

======================

Current btf encoding of bitfield follows what pahole generates.
For each bitfield, pahole will duplicate the type chain and
put the bitfield size at the final int or enum type.
Since the BTF enum type cannot encode bit size,
pahole workarounds the issue by generating
an int type whenever the enum bit size is not 32.

For example,
  -bash-4.4$ cat t.c
  typedef int ___int;
  enum A { A1, A2, A3 };
  struct t {
    int a[5];
    ___int b:4;
    volatile enum A c:4;
  } g;
  -bash-4.4$ gcc -c -O2 -g t.c
The current kernel supports the following BTF encoding:
  $ pahole -JV t.o
  [1] TYPEDEF ___int type_id=2
  [2] INT int size=4 bit_offset=0 nr_bits=32 encoding=SIGNED
  [3] ENUM A size=4 vlen=3
        A1 val=0
        A2 val=1
        A3 val=2
  [4] STRUCT t size=24 vlen=3
        a type_id=5 bits_offset=0
        b type_id=9 bits_offset=160
        c type_id=11 bits_offset=164
  [5] ARRAY (anon) type_id=2 index_type_id=2 nr_elems=5
  [6] INT sizetype size=8 bit_offset=0 nr_bits=64 encoding=(none)
  [7] VOLATILE (anon) type_id=3
  [8] INT int size=1 bit_offset=0 nr_bits=4 encoding=(none)
  [9] TYPEDEF ___int type_id=8
  [10] INT (anon) size=1 bit_offset=0 nr_bits=4 encoding=SIGNED
  [11] VOLATILE (anon) type_id=10

Two issues are in the above:
  . by changing enum type to int, we lost the original
    type information and this will not be ideal later
    when we try to convert BTF to a header file.
  . the type duplication for bitfields will cause
    BTF bloat. Duplicated types cannot be deduplicated
    later if the bitfield size is different.

To fix this issue, this patch implemented a compatible
change for BTF struct type encoding:
  . the bit 31 of struct_type->info, previously reserved,
    now is used to indicate whether bitfield_size is
    encoded in btf_member or not.
  . if bit 31 of struct_type->info is set,
    btf_member->offset will encode like:
      bit 0 - 23: bit offset
      bit 24 - 31: bitfield size
    if bit 31 is not set, the old behavior is preserved:
      bit 0 - 31: bit offset

So if the struct contains a bit field, the maximum bit offset
will be reduced to (2^24 - 1) instead of MAX_UINT. The maximum
bitfield size will be 256 which is enough for today as maximum
bitfield in compiler can be 128 where int128 type is supported.

This kernel patch intends to support the new BTF encoding:
  $ pahole -JV t.o
  [1] TYPEDEF ___int type_id=2
  [2] INT int size=4 bit_offset=0 nr_bits=32 encoding=SIGNED
  [3] ENUM A size=4 vlen=3
        A1 val=0
        A2 val=1
        A3 val=2
  [4] STRUCT t kind_flag=1 size=24 vlen=3
        a type_id=5 bitfield_size=0 bits_offset=0
        b type_id=1 bitfield_size=4 bits_offset=160
        c type_id=7 bitfield_size=4 bits_offset=164
  [5] ARRAY (anon) type_id=2 index_type_id=2 nr_elems=5
  [6] INT sizetype size=8 bit_offset=0 nr_bits=64 encoding=(none)
  [7] VOLATILE (anon) type_id=3

Issue #2 and solution:
======================

Current forward type in BTF does not specify whether the original
type is struct or union. This will not work for type pretty print
and BTF-to-header-file conversion as struct/union must be specified.
  $ cat tt.c
  struct t;
  union u;
  int foo(struct t *t, union u *u) { return 0; }
  $ gcc -c -g -O2 tt.c
  $ pahole -JV tt.o
  [1] INT int size=4 bit_offset=0 nr_bits=32 encoding=SIGNED
  [2] FWD t type_id=0
  [3] PTR (anon) type_id=2
  [4] FWD u type_id=0
  [5] PTR (anon) type_id=4

To fix this issue, similar to issue #1, type->info bit 31
is used. If the bit is set, it is union type. Otherwise, it is
a struct type.

  $ pahole -JV tt.o
  [1] INT int size=4 bit_offset=0 nr_bits=32 encoding=SIGNED
  [2] FWD t kind_flag=0 type_id=0
  [3] PTR (anon) kind_flag=0 type_id=2
  [4] FWD u kind_flag=1 type_id=0
  [5] PTR (anon) kind_flag=0 type_id=4

Pahole/LLVM change:
===================

The new kind_flag functionality has been implemented in pahole
and llvm:
  https://github.com/yonghong-song/pahole/tree/bitfield
  https://github.com/yonghong-song/llvm/tree/bitfield

Note that pahole hasn't implemented func/func_proto kind
and .BTF.ext. So to print function signature with bpftool,
the llvm compiler should be used.

Fixes: 69b693f0 ("bpf: btf: Introduce BPF Type Format (BTF)")
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

Refactor function btf_int_bits_seq_show() by creating
function btf_bitfield_seq_show() which has no dependence
on btf and btf_type. The function btf_bitfield_seq_show()
will be in later patch to directly dump bitfield member values.
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

The current btf_name_by_offset() is returning "(anon)" type name for
the offset == 0 case and "(invalid-name-offset)" for the out-of-bound
offset case.

It fits well for the internal BTF verbose log purpose which
is focusing on type.  For example,
offset == 0 => "(anon)" => anonymous type/name.
Returning non-NULL for the bad offset case is needed
during the BTF verification process because the BTF verifier may
complain about another field first before discovering the name_off
is invalid.

However, it may not be ideal for the newer use case which does not
necessary mean type name.  For example, when logging line_info
in the BPF verifier in the next patch, it is better to log an
empty src line instead of logging "(anon)".

The existing bpf_name_by_offset() is renamed to __bpf_name_by_offset()
and static to btf.c.

A new bpf_name_by_offset() is added for generic context usage.  It
returns "\0" for name_off == 0 (note that btf->strings[0] is "\0")
and NULL for invalid offset.  It allows the caller to decide
what is the best output in its context.

The new btf_name_by_offset() is overlapped with btf_name_offset_valid().
Hence, btf_name_offset_valid() is removed from btf.h to keep the btf.h API
minimal.  The existing btf_name_offset_valid() usage in btf.c could also be
replaced later.
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

Implement bpffs pretty printing for cgroup local storage maps
(both shared and per-cpu).
Output example (captured for tools/testing/selftests/bpf/netcnt_prog.c):

Shared:
  $ cat /sys/fs/bpf/map_2
  # WARNING!! The output is for debug purpose only
  # WARNING!! The output format will change
  {4294968594,1}: {9999,1039896}

Per-cpu:
  $ cat /sys/fs/bpf/map_1
  # WARNING!! The output is for debug purpose only
  # WARNING!! The output format will change
  {4294968594,1}: {
  	cpu0: {0,0,0,0,0}
  	cpu1: {0,0,0,0,0}
  	cpu2: {1,104,0,0,0}
  	cpu3: {0,0,0,0,0}
  }
Signed-off-by: Roman Gushchin <guro@fb.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

This patch adds bpf_line_info support.

It accepts an array of bpf_line_info objects during BPF_PROG_LOAD.
The "line_info", "line_info_cnt" and "line_info_rec_size" are added
to the "union bpf_attr".  The "line_info_rec_size" makes
bpf_line_info extensible in the future.

The new "check_btf_line()" ensures the userspace line_info is valid
for the kernel to use.

When the verifier is translating/patching the bpf_prog (through
"bpf_patch_insn_single()"), the line_infos' insn_off is also
adjusted by the newly added "bpf_adj_linfo()".

If the bpf_prog is jited, this patch also provides the jited addrs (in
aux->jited_linfo) for the corresponding line_info.insn_off.
"bpf_prog_fill_jited_linfo()" is added to fill the aux->jited_linfo.
It is currently called by the x86 jit.  Other jits can also use
"bpf_prog_fill_jited_linfo()" and it will be done in the followup patches.
In the future, if it deemed necessary, a particular jit could also provide
its own "bpf_prog_fill_jited_linfo()" implementation.

A few "*line_info*" fields are added to the bpf_prog_info such
that the user can get the xlated line_info back (i.e. the line_info
with its insn_off reflecting the translated prog).  The jited_line_info
is available if the prog is jited.  It is an array of __u64.
If the prog is not jited, jited_line_info_cnt is 0.

The verifier's verbose log with line_info will be done in
a follow up patch.
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

This patch added name checking for the following types:
 . BTF_KIND_PTR, BTF_KIND_ARRAY, BTF_KIND_VOLATILE,
   BTF_KIND_CONST, BTF_KIND_RESTRICT:
     the name must be null
 . BTF_KIND_STRUCT, BTF_KIND_UNION: the struct/member name
     is either null or a valid identifier
 . BTF_KIND_ENUM: the enum type name is either null or a valid
     identifier; the enumerator name must be a valid identifier.
 . BTF_KIND_FWD: the name must be a valid identifier
 . BTF_KIND_TYPEDEF: the name must be a valid identifier

For those places a valid name is required, the name must be
a valid C identifier. This can be relaxed later if we found
use cases for a different (non-C) frontend.

Fixes: 69b693f0 ("bpf: btf: Introduce BPF Type Format (BTF)")
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

Function btf_name_valid_identifier() have been implemented in
bpf-next commit 2667a262 ("bpf: btf: Add BTF_KIND_FUNC and
BTF_KIND_FUNC_PROTO"). Backport this function so later patch
can use it.

Fixes: 69b693f0 ("bpf: btf: Introduce BPF Type Format (BTF)")
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

There is a spelling mistake in a btf_verifier_log_member message,
fix it.
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

This patch added interface to load a program with the following
additional information:
   . prog_btf_fd
   . func_info, func_info_rec_size and func_info_cnt
where func_info will provide function range and type_id
corresponding to each function.

The func_info_rec_size is introduced in the UAPI to specify
struct bpf_func_info size passed from user space. This
intends to make bpf_func_info structure growable in the future.
If the kernel gets a different bpf_func_info size from userspace,
it will try to handle user request with part of bpf_func_info
it can understand. In this patch, kernel can understand
  struct bpf_func_info {
       __u32   insn_offset;
       __u32   type_id;
  };
If user passed a bpf func_info record size of 16 bytes, the
kernel can still handle part of records with the above definition.

If verifier agrees with function range provided by the user,
the bpf_prog ksym for each function will use the func name
provided in the type_id, which is supposed to provide better
encoding as it is not limited by 16 bytes program name
limitation and this is better for bpf program which contains
multiple subprograms.

The bpf_prog_info interface is also extended to
return btf_id, func_info, func_info_rec_size and func_info_cnt
to userspace, so userspace can print out the function prototype
for each xlated function. The insn_offset in the returned
func_info corresponds to the insn offset for xlated functions.
With other jit related fields in bpf_prog_info, userspace can also
print out function prototypes for each jited function.
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

This patch adds BTF_KIND_FUNC and BTF_KIND_FUNC_PROTO
to support the function debug info.

BTF_KIND_FUNC_PROTO must not have a name (i.e. !t->name_off)
and it is followed by >= 0 'struct bpf_param' objects to
describe the function arguments.

The BTF_KIND_FUNC must have a valid name and it must
refer back to a BTF_KIND_FUNC_PROTO.

The above is the conclusion after the discussion between
Edward Cree, Alexei, Daniel, Yonghong and Martin.

By combining BTF_KIND_FUNC and BTF_LIND_FUNC_PROTO,
a complete function signature can be obtained.  It will be
used in the later patches to learn the function signature of
a running bpf program.
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

This patch breaks up btf_type_is_void() into
btf_type_is_void() and btf_type_is_fwd().

It also adds btf_type_nosize() to better describe it is
testing a type has nosize info.
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

Wenwen Wang reported:

  In btf_parse(), the header of the user-space btf data 'btf_data'
  is firstly parsed and verified through btf_parse_hdr().
  In btf_parse_hdr(), the header is copied from user-space 'btf_data'
  to kernel-space 'btf->hdr' and then verified. If no error happens
  during the verification process, the whole data of 'btf_data',
  including the header, is then copied to 'data' in btf_parse(). It
  is obvious that the header is copied twice here. More importantly,
  no check is enforced after the second copy to make sure the headers
  obtained in these two copies are same. Given that 'btf_data' resides
  in the user space, a malicious user can race to modify the header
  between these two copies. By doing so, the user can inject
  inconsistent data, which can cause undefined behavior of the
  kernel and introduce potential security risk.

This issue is similar to the one fixed in commit 8af03d1a ("bpf:
btf: Fix a missing check bug"). To fix it, this patch copies the user
'btf_data' *before* parsing / verifying the BTF header.

Fixes: 69b693f0 ("bpf: btf: Introduce BPF Type Format (BTF)")
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Co-developed-by: Wenwen Wang <wang6495@umn.edu>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

In btf_parse_hdr(), the length of the btf data header is firstly copied
from the user space to 'hdr_len' and checked to see whether it is larger
than 'btf_data_size'. If yes, an error code EINVAL is returned. Otherwise,
the whole header is copied again from the user space to 'btf->hdr'.
However, after the second copy, there is no check between
'btf->hdr->hdr_len' and 'hdr_len' to confirm that the two copies get the
same value. Given that the btf data is in the user space, a malicious user
can race to change the data between the two copies. By doing so, the user
can provide malicious data to the kernel and cause undefined behavior.

This patch adds a necessary check after the second copy, to make sure
'btf->hdr->hdr_len' has the same value as 'hdr_len'. Otherwise, an error
code EINVAL will be returned.
Signed-off-by: Wenwen Wang <wang6495@umn.edu>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

The end boundary math for type section is incorrect in
btf_check_all_metas().  It just happens that hdr->type_off
is always 0 for now because there are only two sections
(type and string) and string section must be at the end (ensured
in btf_parse_str_sec).

However, type_off may not be 0 if a new section would be added later.
This patch fixes it.

Fixes: f80442a4 ("bpf: btf: Change how section is supported in btf_header")
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

This patch ensures the member->offset of a struct
is in the correct order (i.e the later member's offset cannot
go backward).

The current "pahole -J" BTF encoder does not generate something
like this.  However, checking this can ensure future encoder
will not violate this.

Fixes: 69b693f0 ("bpf: btf: Introduce BPF Type Format (BTF)")
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

This patch shrinks the BTF_INT_BITS() mask.  The current
btf_int_check_meta() ensures the nr_bits of an integer
cannot exceed 64.  Hence, it is mostly an uapi cleanup.

The actual btf usage (i.e. seq_show()) is also modified
to use u8 instead of u16.  The verification (e.g. btf_int_check_meta())
path stays as is to deal with invalid BTF situation.

Fixes: 69b693f0 ("bpf: btf: Introduce BPF Type Format (BTF)")
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

When extracting bitfield from a number, btf_int_bits_seq_show() builds
a mask and accesses least significant byte of the number in a way
specific to little-endian. This patch fixes that by checking endianness
of the machine and then shifting left and right the unneeded bits.

Thanks to Martin Lau for the help in navigating potential pitfalls when
dealing with endianess and for the final solution.

Fixes: b00b8dae ("bpf: btf: Add pretty print capability for data with BTF type info")
Signed-off-by: Okash Khawaja <osk@fb.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

The kvzalloc() function has a 2-factor argument form, kvcalloc(). This
patch replaces cases of:

        kvzalloc(a * b, gfp)

with:
        kvcalloc(a * b, gfp)

as well as handling cases of:

        kvzalloc(a * b * c, gfp)

with:

        kvzalloc(array3_size(a, b, c), gfp)

as it's slightly less ugly than:

        kvcalloc(array_size(a, b), c, gfp)

This does, however, attempt to ignore constant size factors like:

        kvzalloc(4 * 1024, gfp)

though any constants defined via macros get caught up in the conversion.

Any factors with a sizeof() of "unsigned char", "char", and "u8" were
dropped, since they're redundant.

The Coccinelle script used for this was:

// Fix redundant parens around sizeof().
@@
type TYPE;
expression THING, E;
@@

(
  kvzalloc(
-	(sizeof(TYPE)) * E
+	sizeof(TYPE) * E
  , ...)
|
  kvzalloc(
-	(sizeof(THING)) * E
+	sizeof(THING) * E
  , ...)
)

// Drop single-byte sizes and redundant parens.
@@
expression COUNT;
typedef u8;
typedef __u8;
@@

(
  kvzalloc(
-	sizeof(u8) * (COUNT)
+	COUNT
  , ...)
|
  kvzalloc(
-	sizeof(__u8) * (COUNT)
+	COUNT
  , ...)
|
  kvzalloc(
-	sizeof(char) * (COUNT)
+	COUNT
  , ...)
|
  kvzalloc(
-	sizeof(unsigned char) * (COUNT)
+	COUNT
  , ...)
|
  kvzalloc(
-	sizeof(u8) * COUNT
+	COUNT
  , ...)
|
  kvzalloc(
-	sizeof(__u8) * COUNT
+	COUNT
  , ...)
|
  kvzalloc(
-	sizeof(char) * COUNT
+	COUNT
  , ...)
|
  kvzalloc(
-	sizeof(unsigned char) * COUNT
+	COUNT
  , ...)
)

// 2-factor product with sizeof(type/expression) and identifier or constant.
@@
type TYPE;
expression THING;
identifier COUNT_ID;
constant COUNT_CONST;
@@

(
- kvzalloc
+ kvcalloc
  (
-	sizeof(TYPE) * (COUNT_ID)
+	COUNT_ID, sizeof(TYPE)
  , ...)
|
- kvzalloc
+ kvcalloc
  (
-	sizeof(TYPE) * COUNT_ID
+	COUNT_ID, sizeof(TYPE)
  , ...)
|
- kvzalloc
+ kvcalloc
  (
-	sizeof(TYPE) * (COUNT_CONST)
+	COUNT_CONST, sizeof(TYPE)
  , ...)
|
- kvzalloc
+ kvcalloc
  (
-	sizeof(TYPE) * COUNT_CONST
+	COUNT_CONST, sizeof(TYPE)
  , ...)
|
- kvzalloc
+ kvcalloc
  (
-	sizeof(THING) * (COUNT_ID)
+	COUNT_ID, sizeof(THING)
  , ...)
|
- kvzalloc
+ kvcalloc
  (
-	sizeof(THING) * COUNT_ID
+	COUNT_ID, sizeof(THING)
  , ...)
|
- kvzalloc
+ kvcalloc
  (
-	sizeof(THING) * (COUNT_CONST)
+	COUNT_CONST, sizeof(THING)
  , ...)
|
- kvzalloc
+ kvcalloc
  (
-	sizeof(THING) * COUNT_CONST
+	COUNT_CONST, sizeof(THING)
  , ...)
)

// 2-factor product, only identifiers.
@@
identifier SIZE, COUNT;
@@

- kvzalloc
+ kvcalloc
  (
-	SIZE * COUNT
+	COUNT, SIZE
  , ...)

// 3-factor product with 1 sizeof(type) or sizeof(expression), with
// redundant parens removed.
@@
expression THING;
identifier STRIDE, COUNT;
type TYPE;
@@

(
  kvzalloc(
-	sizeof(TYPE) * (COUNT) * (STRIDE)
+	array3_size(COUNT, STRIDE, sizeof(TYPE))
  , ...)
|
  kvzalloc(
-	sizeof(TYPE) * (COUNT) * STRIDE
+	array3_size(COUNT, STRIDE, sizeof(TYPE))
  , ...)
|
  kvzalloc(
-	sizeof(TYPE) * COUNT * (STRIDE)
+	array3_size(COUNT, STRIDE, sizeof(TYPE))
  , ...)
|
  kvzalloc(
-	sizeof(TYPE) * COUNT * STRIDE
+	array3_size(COUNT, STRIDE, sizeof(TYPE))
  , ...)
|
  kvzalloc(
-	sizeof(THING) * (COUNT) * (STRIDE)
+	array3_size(COUNT, STRIDE, sizeof(THING))
  , ...)
|
  kvzalloc(
-	sizeof(THING) * (COUNT) * STRIDE
+	array3_size(COUNT, STRIDE, sizeof(THING))
  , ...)
|
  kvzalloc(
-	sizeof(THING) * COUNT * (STRIDE)
+	array3_size(COUNT, STRIDE, sizeof(THING))
  , ...)
|
  kvzalloc(
-	sizeof(THING) * COUNT * STRIDE
+	array3_size(COUNT, STRIDE, sizeof(THING))
  , ...)
)

// 3-factor product with 2 sizeof(variable), with redundant parens removed.
@@
expression THING1, THING2;
identifier COUNT;
type TYPE1, TYPE2;
@@

(
  kvzalloc(
-	sizeof(TYPE1) * sizeof(TYPE2) * COUNT
+	array3_size(COUNT, sizeof(TYPE1), sizeof(TYPE2))
  , ...)
|
  kvzalloc(
-	sizeof(TYPE1) * sizeof(THING2) * (COUNT)
+	array3_size(COUNT, sizeof(TYPE1), sizeof(TYPE2))
  , ...)
|
  kvzalloc(
-	sizeof(THING1) * sizeof(THING2) * COUNT
+	array3_size(COUNT, sizeof(THING1), sizeof(THING2))
  , ...)
|
  kvzalloc(
-	sizeof(THING1) * sizeof(THING2) * (COUNT)
+	array3_size(COUNT, sizeof(THING1), sizeof(THING2))
  , ...)
|
  kvzalloc(
-	sizeof(TYPE1) * sizeof(THING2) * COUNT
+	array3_size(COUNT, sizeof(TYPE1), sizeof(THING2))
  , ...)
|
  kvzalloc(
-	sizeof(TYPE1) * sizeof(THING2) * (COUNT)
+	array3_size(COUNT, sizeof(TYPE1), sizeof(THING2))
  , ...)
)

// 3-factor product, only identifiers, with redundant parens removed.
@@
identifier STRIDE, SIZE, COUNT;
@@

(
  kvzalloc(
-	(COUNT) * STRIDE * SIZE
+	array3_size(COUNT, STRIDE, SIZE)
  , ...)
|
  kvzalloc(
-	COUNT * (STRIDE) * SIZE
+	array3_size(COUNT, STRIDE, SIZE)
  , ...)
|
  kvzalloc(
-	COUNT * STRIDE * (SIZE)
+	array3_size(COUNT, STRIDE, SIZE)
  , ...)
|
  kvzalloc(
-	(COUNT) * (STRIDE) * SIZE
+	array3_size(COUNT, STRIDE, SIZE)
  , ...)
|
  kvzalloc(
-	COUNT * (STRIDE) * (SIZE)
+	array3_size(COUNT, STRIDE, SIZE)
  , ...)
|
  kvzalloc(
-	(COUNT) * STRIDE * (SIZE)
+	array3_size(COUNT, STRIDE, SIZE)
  , ...)
|
  kvzalloc(
-	(COUNT) * (STRIDE) * (SIZE)
+	array3_size(COUNT, STRIDE, SIZE)
  , ...)
|
  kvzalloc(
-	COUNT * STRIDE * SIZE
+	array3_size(COUNT, STRIDE, SIZE)
  , ...)
)

// Any remaining multi-factor products, first at least 3-factor products,
// when they're not all constants...
@@
expression E1, E2, E3;
constant C1, C2, C3;
@@

(
  kvzalloc(C1 * C2 * C3, ...)
|
  kvzalloc(
-	(E1) * E2 * E3
+	array3_size(E1, E2, E3)
  , ...)
|
  kvzalloc(
-	(E1) * (E2) * E3
+	array3_size(E1, E2, E3)
  , ...)
|
  kvzalloc(
-	(E1) * (E2) * (E3)
+	array3_size(E1, E2, E3)
  , ...)
|
  kvzalloc(
-	E1 * E2 * E3
+	array3_size(E1, E2, E3)
  , ...)
)

// And then all remaining 2 factors products when they're not all constants,
// keeping sizeof() as the second factor argument.
@@
expression THING, E1, E2;
type TYPE;
constant C1, C2, C3;
@@

(
  kvzalloc(sizeof(THING) * C2, ...)
|
  kvzalloc(sizeof(TYPE) * C2, ...)
|
  kvzalloc(C1 * C2 * C3, ...)
|
  kvzalloc(C1 * C2, ...)
|
- kvzalloc
+ kvcalloc
  (
-	sizeof(TYPE) * (E2)
+	E2, sizeof(TYPE)
  , ...)
|
- kvzalloc
+ kvcalloc
  (
-	sizeof(TYPE) * E2
+	E2, sizeof(TYPE)
  , ...)
|
- kvzalloc
+ kvcalloc
  (
-	sizeof(THING) * (E2)
+	E2, sizeof(THING)
  , ...)
|
- kvzalloc
+ kvcalloc
  (
-	sizeof(THING) * E2
+	E2, sizeof(THING)
  , ...)
|
- kvzalloc
+ kvcalloc
  (
-	(E1) * E2
+	E1, E2
  , ...)
|
- kvzalloc
+ kvcalloc
  (
-	(E1) * (E2)
+	E1, E2
  , ...)
|
- kvzalloc
+ kvcalloc
  (
-	E1 * E2
+	E1, E2
  , ...)
)
Signed-off-by: Kees Cook <keescook@chromium.org>

The t->type in BTF_KIND_FWD is not used.  It must be 0.
This patch ensures that and also adds a test case in test_btf.c
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

This patch ensures array's t->size is 0.

The array size is decided by its individual elem's size and the
number of elements.  Hence, t->size is not used and
it must be 0.

A test case is added to test_btf.c
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

gcc warns about a noreturn function possibly returning in
some configurations:

kernel/bpf/btf.c: In function 'env_type_is_resolve_sink':
kernel/bpf/btf.c:729:1: error: control reaches end of non-void function [-Werror=return-type]

Using BUG() instead of BUG_ON() avoids that warning and otherwise
does the exact same thing.

Fixes: eb3f595d ("bpf: btf: Validate type reference")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

Sparse warning:
kernel/bpf/btf.c:1985:34: warning: Variable length array is used.

This patch directly uses ARRAY_SIZE().

Fixes: f80442a4 ("bpf: btf: Change how section is supported in btf_header")
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>