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: eb3f595dab ("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 1dc9285184 ("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: 1dc9285184 ("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 38d5d3b3d5 ("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>
An ipvlan bug fix in 'net' conflicted with the abstraction away
of the IPV6 specific support in 'net-next'.
Similarly, a bug fix for mlx5 in 'net' conflicted with the flow
action conversion in 'net-next'.
Signed-off-by: David S. Miller <davem@davemloft.net>
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: 2667a2626f ("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>
Daniel Borkmann says:
====================
pull-request: bpf-next 2019-01-29
The following pull-request contains BPF updates for your *net-next* tree.
The main changes are:
1) Teach verifier dead code removal, this also allows for optimizing /
removing conditional branches around dead code and to shrink the
resulting image. Code store constrained architectures like nfp would
have hard time doing this at JIT level, from Jakub.
2) Add JMP32 instructions to BPF ISA in order to allow for optimizing
code generation for 32-bit sub-registers. Evaluation shows that this
can result in code reduction of ~5-20% compared to 64 bit-only code
generation. Also add implementation for most JITs, from Jiong.
3) Add support for __int128 types in BTF which is also needed for
vmlinux's BTF conversion to work, from Yonghong.
4) Add a new command to bpftool in order to dump a list of BPF-related
parameters from the system or for a specific network device e.g. in
terms of available prog/map types or helper functions, from Quentin.
5) Add AF_XDP sock_diag interface for querying sockets from user
space which provides information about the RX/TX/fill/completion
rings, umem, memory usage etc, from Björn.
6) Add skb context access for skb_shared_info->gso_segs field, from Eric.
7) Add support for testing flow dissector BPF programs by extending
existing BPF_PROG_TEST_RUN infrastructure, from Stanislav.
8) Split BPF kselftest's test_verifier into various subgroups of tests
in order better deal with merge conflicts in this area, from Jakub.
9) Add support for queue/stack manipulations in bpftool, from Stanislav.
10) Document BTF, from Yonghong.
11) Dump supported ELF section names in libbpf on program load
failure, from Taeung.
12) Silence a false positive compiler warning in verifier's BTF
handling, from Peter.
13) Fix help string in bpftool's feature probing, from Prashant.
14) Remove duplicate includes in BPF kselftests, from Yue.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
Initially in commit 69b693f0ae ("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 23127b33ec ("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: 23127b33ec ("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 9d5f9f701b ("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: 9d5f9f701b ("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 9d5f9f701b ("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/bitfieldhttps://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: 69b693f0ae ("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>
Daniel Borkmann says:
====================
pull-request: bpf-next 2018-12-11
The following pull-request contains BPF updates for your *net-next* tree.
It has three minor merge conflicts, resolutions:
1) tools/testing/selftests/bpf/test_verifier.c
Take first chunk with alignment_prevented_execution.
2) net/core/filter.c
[...]
case bpf_ctx_range_ptr(struct __sk_buff, flow_keys):
case bpf_ctx_range(struct __sk_buff, wire_len):
return false;
[...]
3) include/uapi/linux/bpf.h
Take the second chunk for the two cases each.
The main changes are:
1) Add support for BPF line info via BTF and extend libbpf as well
as bpftool's program dump to annotate output with BPF C code to
facilitate debugging and introspection, from Martin.
2) Add support for BPF_ALU | BPF_ARSH | BPF_{K,X} in interpreter
and all JIT backends, from Jiong.
3) Improve BPF test coverage on archs with no efficient unaligned
access by adding an "any alignment" flag to the BPF program load
to forcefully disable verifier alignment checks, from David.
4) Add a new bpf_prog_test_run_xattr() API to libbpf which allows for
proper use of BPF_PROG_TEST_RUN with data_out, from Lorenz.
5) Extend tc BPF programs to use a new __sk_buff field called wire_len
for more accurate accounting of packets going to wire, from Petar.
6) Improve bpftool to allow dumping the trace pipe from it and add
several improvements in bash completion and map/prog dump,
from Quentin.
7) Optimize arm64 BPF JIT to always emit movn/movk/movk sequence for
kernel addresses and add a dedicated BPF JIT backend allocator,
from Ard.
8) Add a BPF helper function for IR remotes to report mouse movements,
from Sean.
9) Various cleanups in BPF prog dump e.g. to make UAPI bpf_prog_info
member naming consistent with existing conventions, from Yonghong
and Song.
10) Misc cleanups and improvements in allowing to pass interface name
via cmdline for xdp1 BPF example, from Matteo.
11) Fix a potential segfault in BPF sample loader's kprobes handling,
from Daniel T.
12) Fix SPDX license in libbpf's README.rst, from Andrey.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
Several conflicts, seemingly all over the place.
I used Stephen Rothwell's sample resolutions for many of these, if not
just to double check my own work, so definitely the credit largely
goes to him.
The NFP conflict consisted of a bug fix (moving operations
past the rhashtable operation) while chaning the initial
argument in the function call in the moved code.
The net/dsa/master.c conflict had to do with a bug fix intermixing of
making dsa_master_set_mtu() static with the fixing of the tagging
attribute location.
cls_flower had a conflict because the dup reject fix from Or
overlapped with the addition of port range classifiction.
__set_phy_supported()'s conflict was relatively easy to resolve
because Andrew fixed it in both trees, so it was just a matter
of taking the net-next copy. Or at least I think it was :-)
Joe Stringer's fix to the handling of netns id 0 in bpf_sk_lookup()
intermixed with changes on how the sdif and caller_net are calculated
in these code paths in net-next.
The remaining BPF conflicts were largely about the addition of the
__bpf_md_ptr stuff in 'net' overlapping with adjustments and additions
to the relevant data structure where the MD pointer macros are used.
Signed-off-by: David S. Miller <davem@davemloft.net>
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: 69b693f0ae ("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 2667a2626f ("bpf: btf: Add BTF_KIND_FUNC and
BTF_KIND_FUNC_PROTO"). Backport this function so later patch
can use it.
Fixes: 69b693f0ae ("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 8af03d1ae2 ("bpf:
btf: Fix a missing check bug"). To fix it, this patch copies the user
'btf_data' *before* parsing / verifying the BTF header.
Fixes: 69b693f0ae ("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: f80442a4cd ("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: 69b693f0ae ("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: 69b693f0ae ("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: b00b8daec8 ("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 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: eb3f595dab ("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: f80442a4cd ("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>
This patch does the followings:
1. Limit BTF_MAX_TYPES and BTF_MAX_NAME_OFFSET to 64k. We can
raise it later.
2. Remove the BTF_TYPE_PARENT and BTF_STR_TBL_ELF_ID. They are
currently encoded at the highest bit of a u32.
It is because the current use case does not require supporting
parent type (i.e type_id referring to a type in another BTF file).
It also does not support referring to a string in ELF.
The BTF_TYPE_PARENT and BTF_STR_TBL_ELF_ID checks are replaced
by BTF_TYPE_ID_CHECK and BTF_STR_OFFSET_CHECK which are
defined in btf.c instead of uapi/linux/btf.h.
3. Limit the BTF_INFO_KIND from 5 bits to 4 bits which is enough.
There is unused bits headroom if we ever needed it later.
4. The root bit in BTF_INFO is also removed because it is not
used in the current use case.
5. Remove BTF_INT_VARARGS since func type is not supported now.
The BTF_INT_ENCODING is limited to 4 bits instead of 8 bits.
The above can be added back later because the verifier
ensures the unused bits are zeros.
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Instead of ingoring the array->index_type field. Enforce that
it must be a BTF_KIND_INT in size 1/2/4/8 bytes.
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
There are currently unused section descriptions in the btf_header. Those
sections are here to support future BTF use cases. For example, the
func section (func_off) is to support function signature (e.g. the BPF
prog function signature).
Instead of spelling out all potential sections up-front in the btf_header.
This patch makes changes to btf_header such that extending it (e.g. adding
a section) is possible later. The unused ones can be removed for now and
they can be added back later.
This patch:
1. adds a hdr_len to the btf_header. It will allow adding
sections (and other info like parent_label and parent_name)
later. The check is similar to the existing bpf_attr.
If a user passes in a longer hdr_len, the kernel
ensures the extra tailing bytes are 0.
2. allows the section order in the BTF object to be
different from its sec_off order in btf_header.
3. each sec_off is followed by a sec_len. It must not have gap or
overlapping among sections.
The string section is ensured to be at the end due to the 4 bytes
alignment requirement of the type section.
The above changes will allow enough flexibility to
add new sections (and other info) to the btf_header later.
This patch also removes an unnecessary !err check
at the end of btf_parse().
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
During BPF_OBJ_GET_INFO_BY_FD on a btf_fd, the current bpf_attr's
info.info is directly filled with the BTF binary data. It is
not extensible. In this case, we want to add BTF ID.
This patch adds "struct bpf_btf_info" which has the BTF ID as
one of its member. The BTF binary data itself is exposed through
the "btf" and "btf_size" members.
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Alexei Starovoitov <ast@fb.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This patch gives an ID to each loaded BTF. The ID is allocated by
the idr like the existing prog-id and map-id.
The bpf_put(map->btf) is moved to __bpf_map_put() so that the
userspace can stop seeing the BTF ID ASAP when the last BTF
refcnt is gone.
It also makes BTF accessible from userspace through the
1. new BPF_BTF_GET_FD_BY_ID command. It is limited to CAP_SYS_ADMIN
which is inline with the BPF_BTF_LOAD cmd and the existing
BPF_[MAP|PROG]_GET_FD_BY_ID cmd.
2. new btf_id (and btf_key_id + btf_value_id) in "struct bpf_map_info"
Once the BTF ID handler is accessible from userspace, freeing a BTF
object has to go through a rcu period. The BPF_BTF_GET_FD_BY_ID cmd
can then be done under a rcu_read_lock() instead of taking
spin_lock.
[Note: A similar rcu usage can be done to the existing
bpf_prog_get_fd_by_id() in a follow up patch]
When processing the BPF_BTF_GET_FD_BY_ID cmd,
refcount_inc_not_zero() is needed because the BTF object
could be already in the rcu dead row . btf_get() is
removed since its usage is currently limited to btf.c
alone. refcount_inc() is used directly instead.
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Alexei Starovoitov <ast@fb.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
If CONFIG_REFCOUNT_FULL=y, refcount_inc() WARN when refcount is 0.
When creating a new btf, the initial btf->refcnt is 0 and
triggered the following:
[ 34.855452] refcount_t: increment on 0; use-after-free.
[ 34.856252] WARNING: CPU: 6 PID: 1857 at lib/refcount.c:153 refcount_inc+0x26/0x30
....
[ 34.868809] Call Trace:
[ 34.869168] btf_new_fd+0x1af6/0x24d0
[ 34.869645] ? btf_type_seq_show+0x200/0x200
[ 34.870212] ? lock_acquire+0x3b0/0x3b0
[ 34.870726] ? security_capable+0x54/0x90
[ 34.871247] __x64_sys_bpf+0x1b2/0x310
[ 34.871761] ? __ia32_sys_bpf+0x310/0x310
[ 34.872285] ? bad_area_access_error+0x310/0x310
[ 34.872894] do_syscall_64+0x95/0x3f0
This patch uses refcount_set() instead.
Reported-by: Yonghong Song <yhs@fb.com>
Tested-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This patch cleans up btf.h in uapi:
1) Rename "name" to "name_off" to better reflect it is an offset to the
string section instead of a char array.
2) Remove unused value BTF_FLAGS_COMPR and BTF_MAGIC_SWAP
Suggested-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This patch adds BPF_OBJ_GET_INFO_BY_FD support to BTF fd.
The original BTF data, which was used to create the BTF fd during
the earlier BPF_BTF_LOAD call, will be returned.
The userspace is expected to allocate buffer
to info.info and the buffer size is set to info.info_len before
calling BPF_OBJ_GET_INFO_BY_FD.
The original BTF data is copied to the userspace buffer (info.info).
Only upto the user's specified info.info_len will be copied.
The original BTF data size is set to info.info_len. The userspace
needs to check if it is bigger than its allocated buffer size.
If it is, the userspace should realloc with the kernel-returned
info.info_len and call the BPF_OBJ_GET_INFO_BY_FD again.
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Alexei Starovoitov <ast@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This patch adds a BPF_BTF_LOAD command which
1) loads and verifies the BTF (implemented in earlier patches)
2) returns a BTF fd to userspace. In the next patch, the
BTF fd can be specified during BPF_MAP_CREATE.
It currently limits to CAP_SYS_ADMIN.
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Alexei Starovoitov <ast@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This patch adds pretty print capability for data with BTF type info.
The current usage is to allow pretty print for a BPF map.
The next few patches will allow a read() on a pinned map with BTF
type info for its key and value.
This patch uses the seq_printf() infra.
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Alexei Starovoitov <ast@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This patch checks a few things of struct's members:
1) It has a valid size (e.g. a "const void" is invalid)
2) A member's size (+ its member's offset) does not exceed
the containing struct's size.
3) The member's offset satisfies the alignment requirement
The above can only be done after the needs_resolve member's type
is resolved. Hence, the above is done together in
btf_struct_resolve().
Each possible member's type (e.g. int, enum, modifier...) implements
the check_member() ops which will be called from btf_struct_resolve().
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Alexei Starovoitov <ast@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
After collecting all btf_type in the first pass in an earlier patch,
the second pass (in this patch) can validate the reference types
(e.g. the referring type does exist and it does not refer to itself).
While checking the reference type, it also gathers other information (e.g.
the size of an array). This info will be useful in checking the
struct's members in a later patch. They will also be useful in doing
pretty print later.
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Alexei Starovoitov <ast@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This patch introduces BPF type Format (BTF).
BTF (BPF Type Format) is the meta data format which describes
the data types of BPF program/map. Hence, it basically focus
on the C programming language which the modern BPF is primary
using. The first use case is to provide a generic pretty print
capability for a BPF map.
BTF has its root from CTF (Compact C-Type format). To simplify
the handling of BTF data, BTF removes the differences between
small and big type/struct-member. Hence, BTF consistently uses u32
instead of supporting both "one u16" and "two u32 (+padding)" in
describing type and struct-member.
It also raises the number of types (and functions) limit
from 0x7fff to 0x7fffffff.
Due to the above changes, the format is not compatible to CTF.
Hence, BTF starts with a new BTF_MAGIC and version number.
This patch does the first verification pass to the BTF. The first
pass checks:
1. meta-data size (e.g. It does not go beyond the total btf's size)
2. name_offset is valid
3. Each BTF_KIND (e.g. int, enum, struct....) does its
own check of its meta-data.
Some other checks, like checking a struct's member is referring
to a valid type, can only be done in the second pass. The second
verification pass will be implemented in the next patch.
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Alexei Starovoitov <ast@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
