linux-stable.git/tools/lib/bpf, branch v6.9.6

libbpf: fix feature detectors when using token_fd

2024-05-30T07:45:02+00:00

[ Upstream commit 1de27bba6d50a909647f304eadc0f7c59a842a50 ]

Adjust `union bpf_attr` size passed to kernel in two feature-detecting
functions to take into account prog_token_fd field.

Libbpf is avoiding memset()'ing entire `union bpf_attr` by only using
minimal set of bpf_attr's fields. Two places have been missed when
wiring BPF token support in libbpf's feature detection logic.

Fix them trivially.

Fixes: f3dcee938f48 ("libbpf: Wire up token_fd into feature probing logic")
Signed-off-by: Andrii Nakryiko 
Link: https://lore.kernel.org/r/20240513180804.403775-1-andrii@kernel.org
Signed-off-by: Alexei Starovoitov 
Signed-off-by: Sasha Levin

libbpf: Fix error message in attach_kprobe_multi

2024-05-30T07:44:30+00:00

[ Upstream commit 7c13ef16e87ac2e44d16c0468b1191bceb06f95c ]

We just failed to retrieve pattern, so we need to print spec instead.

Fixes: ddc6b04989eb ("libbpf: Add bpf_program__attach_kprobe_multi_opts function")
Reported-by: Andrii Nakryiko 
Signed-off-by: Jiri Olsa 
Signed-off-by: Andrii Nakryiko 
Link: https://lore.kernel.org/bpf/20240502075541.1425761-2-jolsa@kernel.org
Signed-off-by: Sasha Levin

libbpf: Prevent null-pointer dereference when prog to load has no BTF

2024-05-30T07:44:11+00:00

[ Upstream commit 9bf48fa19a4b1d186e08b20bf7e5de26a15644fb ]

In bpf_objec_load_prog(), there's no guarantee that obj->btf is non-NULL
when passing it to btf__fd(), and this function does not perform any
check before dereferencing its argument (as bpf_object__btf_fd() used to
do). As a consequence, we get segmentation fault errors in bpftool (for
example) when trying to load programs that come without BTF information.

v2: Keep btf__fd() in the fix instead of reverting to bpf_object__btf_fd().

Fixes: df7c3f7d3a3d ("libbpf: make uniform use of btf__fd() accessor inside libbpf")
Suggested-by: Andrii Nakryiko 
Signed-off-by: Quentin Monnet 
Signed-off-by: Andrii Nakryiko 
Link: https://lore.kernel.org/bpf/20240314150438.232462-1-qmo@kernel.org
Signed-off-by: Sasha Levin

Merge tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf

2024-03-26T11:55:18+00:00

Daniel Borkmann says:

====================
pull-request: bpf 2024-03-25

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

We've added 17 non-merge commits during the last 12 day(s) which contain
a total of 19 files changed, 184 insertions(+), 61 deletions(-).

The main changes are:

1) Fix an arm64 BPF JIT bug in BPF_LDX_MEMSX implementation's offset handling
   found via test_bpf module, from Puranjay Mohan.

2) Various fixups to the BPF arena code in particular in the BPF verifier and
   around BPF selftests to match latest corresponding LLVM implementation,
   from Puranjay Mohan and Alexei Starovoitov.

3) Fix xsk to not assume that metadata is always requested in TX completion,
   from Stanislav Fomichev.

4) Fix riscv BPF JIT's kfunc parameter incompatibility between BPF and the riscv
   ABI which requires sign-extension on int/uint, from Pu Lehui.

5) Fix s390x BPF JIT's bpf_plt pointer arithmetic which triggered a crash when
   testing struct_ops, from Ilya Leoshkevich.

6) Fix libbpf's arena mmap handling which had incorrect u64-to-pointer cast on
   32-bit architectures, from Andrii Nakryiko.

7) Fix libbpf to define MFD_CLOEXEC when not available, from Arnaldo Carvalho de Melo.

8) Fix arm64 BPF JIT implementation for 32bit unconditional bswap which
   resulted in an incorrect swap as indicated by test_bpf, from Artem Savkov.

9) Fix BPF man page build script to use silent mode, from Hangbin Liu.

* tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf:
  riscv, bpf: Fix kfunc parameters incompatibility between bpf and riscv abi
  bpf: verifier: reject addr_space_cast insn without arena
  selftests/bpf: verifier_arena: fix mmap address for arm64
  bpf: verifier: fix addr_space_cast from as(1) to as(0)
  libbpf: Define MFD_CLOEXEC if not available
  arm64: bpf: fix 32bit unconditional bswap
  bpf, arm64: fix bug in BPF_LDX_MEMSX
  libbpf: fix u64-to-pointer cast on 32-bit arches
  s390/bpf: Fix bpf_plt pointer arithmetic
  xsk: Don't assume metadata is always requested in TX completion
  selftests/bpf: Add arena test case for 4Gbyte corner case
  selftests/bpf: Remove hard coded PAGE_SIZE macro.
  libbpf, selftests/bpf: Adjust libbpf, bpftool, selftests to match LLVM
  bpf: Clarify bpf_arena comments.
  MAINTAINERS: Update email address for Quentin Monnet
  scripts/bpf_doc: Use silent mode when exec make cmd
  bpf: Temporarily disable atomic operations in BPF arena
====================

Link: https://lore.kernel.org/r/20240325213520.26688-1-daniel@iogearbox.net
Signed-off-by: Paolo Abeni

Merge tag 'kbuild-v6.9' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

2024-03-21T21:41:00+00:00

Pull Kbuild updates from Masahiro Yamada:

 - Generate a list of built DTB files (arch/*/boot/dts/dtbs-list)

 - Use more threads when building Debian packages in parallel

 - Fix warnings shown during the RPM kernel package uninstallation

 - Change OBJECT_FILES_NON_STANDARD_*.o etc. to take a relative path to
   Makefile

 - Support GCC's -fmin-function-alignment flag

 - Fix a null pointer dereference bug in modpost

 - Add the DTB support to the RPM package

 - Various fixes and cleanups in Kconfig

* tag 'kbuild-v6.9' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (67 commits)
  kconfig: tests: test dependency after shuffling choices
  kconfig: tests: add a test for randconfig with dependent choices
  kconfig: tests: support KCONFIG_SEED for the randconfig runner
  kbuild: rpm-pkg: add dtb files in kernel rpm
  kconfig: remove unneeded menu_is_visible() call in conf_write_defconfig()
  kconfig: check prompt for choice while parsing
  kconfig: lxdialog: remove unused dialog colors
  kconfig: lxdialog: fix button color for blackbg theme
  modpost: fix null pointer dereference
  kbuild: remove GCC's default -Wpacked-bitfield-compat flag
  kbuild: unexport abs_srctree and abs_objtree
  kbuild: Move -Wenum-{compare-conditional,enum-conversion} into W=1
  kconfig: remove named choice support
  kconfig: use linked list in get_symbol_str() to iterate over menus
  kconfig: link menus to a symbol
  kbuild: fix inconsistent indentation in top Makefile
  kbuild: Use -fmin-function-alignment when available
  alpha: merge two entries for CONFIG_ALPHA_GAMMA
  alpha: merge two entries for CONFIG_ALPHA_EV4
  kbuild: change DTC_FLAGS_.o to take the path relative to $(obj)
  ...

libbpf: Define MFD_CLOEXEC if not available

2024-03-21T18:27:17+00:00

Since its going directly to the syscall to avoid not having
memfd_create() available in some systems, do the same for its
MFD_CLOEXEC flags, defining it if not available.

This fixes the build in those systems, noticed while building perf on a
set of build containers.

Fixes: 9fa5e1a180aa639f ("libbpf: Call memfd_create() syscall directly")
Signed-off-by: Arnaldo Carvalho de Melo 
Signed-off-by: Andrii Nakryiko 
Link: https://lore.kernel.org/bpf/ZfxZ9nCyKvwmpKkE@x1

libbpf: fix u64-to-pointer cast on 32-bit arches

2024-03-20T05:54:04+00:00

It's been reported that (void *)map->map_extra is causing compilation
warnings on 32-bit architectures. It's easy enough to fix this by
casting to long first.

Fixes: 79ff13e99169 ("libbpf: Add support for bpf_arena.")
Reported-by: Ryan Eatmon 
Signed-off-by: Andrii Nakryiko 
Message-ID: <20240319215143.1279312-1-andrii@kernel.org>
Signed-off-by: Alexei Starovoitov

libbpf, selftests/bpf: Adjust libbpf, bpftool, selftests to match LLVM

2024-03-15T21:24:00+00:00

The selftests use
to tell LLVM about special pointers. For LLVM there is nothing "arena"
about them. They are simply pointers in a different address space.
Hence LLVM diff https://github.com/llvm/llvm-project/pull/85161 renamed:
. macro __BPF_FEATURE_ARENA_CAST -> __BPF_FEATURE_ADDR_SPACE_CAST
. global variables in __attribute__((address_space(N))) are now
  placed in section named ".addr_space.N" instead of ".arena.N".

Adjust libbpf, bpftool, and selftests to match LLVM.

Signed-off-by: Alexei Starovoitov 
Signed-off-by: Andrii Nakryiko 
Acked-by: Stanislav Fomichev 
Link: https://lore.kernel.org/bpf/20240315021834.62988-3-alexei.starovoitov@gmail.com

libbpf: Recognize __arena global variables.

2024-03-11T22:43:35+00:00

LLVM automatically places __arena variables into ".arena.1" ELF section.
In order to use such global variables bpf program must include definition
of arena map in ".maps" section, like:
struct {
       __uint(type, BPF_MAP_TYPE_ARENA);
       __uint(map_flags, BPF_F_MMAPABLE);
       __uint(max_entries, 1000);         /* number of pages */
       __ulong(map_extra, 2ull << 44);    /* start of mmap() region */
} arena SEC(".maps");

libbpf recognizes both uses of arena and creates single `struct bpf_map *`
instance in libbpf APIs.
".arena.1" ELF section data is used as initial data image, which is exposed
through skeleton and bpf_map__initial_value() to the user, if they need to tune
it before the load phase. During load phase, this initial image is copied over
into mmap()'ed region corresponding to arena, and discarded.

Few small checks here and there had to be added to make sure this
approach works with bpf_map__initial_value(), mostly due to hard-coded
assumption that map->mmaped is set up with mmap() syscall and should be
munmap()'ed. For arena, .arena.1 can be (much) smaller than maximum
arena size, so this smaller data size has to be tracked separately.
Given it is enforced that there is only one arena for entire bpf_object
instance, we just keep it in a separate field. This can be generalized
if necessary later.

All global variables from ".arena.1" section are accessible from user space
via skel->arena->name_of_var.

For bss/data/rodata the skeleton/libbpf perform the following sequence:
1. addr = mmap(MAP_ANONYMOUS)
2. user space optionally modifies global vars
3. map_fd = bpf_create_map()
4. bpf_update_map_elem(map_fd, addr) // to store values into the kernel
5. mmap(addr, MAP_FIXED, map_fd)
after step 5 user spaces see the values it wrote at step 2 at the same addresses

arena doesn't support update_map_elem. Hence skeleton/libbpf do:
1. addr = malloc(sizeof SEC ".arena.1")
2. user space optionally modifies global vars
3. map_fd = bpf_create_map(MAP_TYPE_ARENA)
4. real_addr = mmap(map->map_extra, MAP_SHARED | MAP_FIXED, map_fd)
5. memcpy(real_addr, addr) // this will fault-in and allocate pages

At the end look and feel of global data vs __arena global data is the same from
bpf prog pov.

Another complication is:
struct {
  __uint(type, BPF_MAP_TYPE_ARENA);
} arena SEC(".maps");

int __arena foo;
int bar;

  ptr1 = &foo;   // relocation against ".arena.1" section
  ptr2 = &arena; // relocation against ".maps" section
  ptr3 = &bar;   // relocation against ".bss" section

Fo the kernel ptr1 and ptr2 has point to the same arena's map_fd
while ptr3 points to a different global array's map_fd.
For the verifier:
ptr1->type == unknown_scalar
ptr2->type == const_ptr_to_map
ptr3->type == ptr_to_map_value

After verification, from JIT pov all 3 ptr-s are normal ld_imm64 insns.

Signed-off-by: Andrii Nakryiko 
Signed-off-by: Alexei Starovoitov 
Signed-off-by: Andrii Nakryiko 
Acked-by: Quentin Monnet 
Link: https://lore.kernel.org/bpf/20240308010812.89848-11-alexei.starovoitov@gmail.com

libbpf: Add support for bpf_arena.

2024-03-11T22:37:24+00:00

mmap() bpf_arena right after creation, since the kernel needs to
remember the address returned from mmap. This is user_vm_start.
LLVM will generate bpf_arena_cast_user() instructions where
necessary and JIT will add upper 32-bit of user_vm_start
to such pointers.

Fix up bpf_map_mmap_sz() to compute mmap size as
map->value_size * map->max_entries for arrays and
PAGE_SIZE * map->max_entries for arena.

Don't set BTF at arena creation time, since it doesn't support it.

Signed-off-by: Alexei Starovoitov 
Signed-off-by: Andrii Nakryiko 
Link: https://lore.kernel.org/bpf/20240308010812.89848-9-alexei.starovoitov@gmail.com