linux.git/tools/bpf, branch master Linux kernel source tree bpftool: Fix vmlinux BTF leak in cgroup commands 2026-06-22T01:02:10+00:00 Yichong Chen chenyichong@uniontech.com 2026-06-17T09:01:17+00:00 bda6a7308ef8e79cfbb7d09e48e1c7ffaa522269 bpftool cgroup show and tree call libbpf_find_kernel_btf() to resolve attach_btf names, but never release the returned BTF object. For cgroup tree, do_show_tree_fn() is called once for each cgroup visited by nftw(). When more than one cgroup has attached programs, each callback overwrites btf_vmlinux with a new object and loses the previous allocation. Load vmlinux BTF only once during a tree walk and release it when cgroup show or tree completes. Reset btf_vmlinux_id at the same time so batch mode starts with clean state. Fixes: 596f5fb2ea2a ("bpftool: implement cgroup tree for BPF_LSM_CGROUP") Signed-off-by: Yichong Chen <chenyichong@uniontech.com> Reviewed-by: Quentin Monnet <qmo@kernel.org> Link: https://lore.kernel.org/r/24357C69B4405079+20260617090117.280222-1-chenyichong@uniontech.com Signed-off-by: Alexei Starovoitov <ast@kernel.org> 
bpftool cgroup show and tree call libbpf_find_kernel_btf() to
resolve attach_btf names, but never release the returned BTF object.

For cgroup tree, do_show_tree_fn() is called once for each cgroup
visited by nftw(). When more than one cgroup has attached programs,
each callback overwrites btf_vmlinux with a new object and loses the
previous allocation.

Load vmlinux BTF only once during a tree walk and release it when
cgroup show or tree completes. Reset btf_vmlinux_id at the same time
so batch mode starts with clean state.

Fixes: 596f5fb2ea2a ("bpftool: implement cgroup tree for BPF_LSM_CGROUP")
Signed-off-by: Yichong Chen <chenyichong@uniontech.com>
Reviewed-by: Quentin Monnet <qmo@kernel.org>
Link: https://lore.kernel.org/r/24357C69B4405079+20260617090117.280222-1-chenyichong@uniontech.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
tools/bpf: build: Append extra cflags 2026-06-15T00:32:53+00:00 Leo Yan leo.yan@arm.com 2026-06-02T14:47:14+00:00 b40ba139371c2ba4beffe0533c6d85fda9bc932c Append EXTRA_CFLAGS to CFLAGS so that additional flags can be applied to the compiler. Signed-off-by: Leo Yan <leo.yan@arm.com> Acked-by: Ihor Solodrai <ihor.solodrai@linux.dev> Link: https://lore.kernel.org/r/20260602-tools_build_fix_zero_init_bpf_only-v2-5-c76e5250ea1c@arm.com Signed-off-by: Alexei Starovoitov <ast@kernel.org> 
Append EXTRA_CFLAGS to CFLAGS so that additional flags can be applied to
the compiler.

Signed-off-by: Leo Yan <leo.yan@arm.com>
Acked-by: Ihor Solodrai <ihor.solodrai@linux.dev>
Link: https://lore.kernel.org/r/20260602-tools_build_fix_zero_init_bpf_only-v2-5-c76e5250ea1c@arm.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
bpftool: Append extra host flags 2026-06-15T00:32:53+00:00 Leo Yan leo.yan@arm.com 2026-06-02T14:47:12+00:00 3f2fec5b02b6efa1aad3238943858234751ac0f3 Append HOST_EXTRACFLAGS to HOST_CFLAGS so that additional flags can be applied to the host compiler. Acked-by: Quentin Monnet <qmo@kernel.org> Signed-off-by: Leo Yan <leo.yan@arm.com> Link: https://lore.kernel.org/r/20260602-tools_build_fix_zero_init_bpf_only-v2-3-c76e5250ea1c@arm.com Signed-off-by: Alexei Starovoitov <ast@kernel.org> 
Append HOST_EXTRACFLAGS to HOST_CFLAGS so that additional flags can be
applied to the host compiler.

Acked-by: Quentin Monnet <qmo@kernel.org>
Signed-off-by: Leo Yan <leo.yan@arm.com>
Link: https://lore.kernel.org/r/20260602-tools_build_fix_zero_init_bpf_only-v2-3-c76e5250ea1c@arm.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
bpftool: Avoid adding EXTRA_CFLAGS to HOST_CFLAGS 2026-06-15T00:32:53+00:00 Leo Yan leo.yan@arm.com 2026-06-02T14:47:11+00:00 956841cbc3d77a9e687182a8bba316e9a2665a50 Prepare for future changes where EXTRA_CFLAGS may include flags not applicable to the host compiler. Move the HOST_CFLAGS assignment before appending EXTRA_CFLAGS to CFLAGS so that HOST_CFLAGS does not inherit flags from EXTRA_CFLAGS. Acked-by: Quentin Monnet <qmo@kernel.org> Signed-off-by: Leo Yan <leo.yan@arm.com> Link: https://lore.kernel.org/r/20260602-tools_build_fix_zero_init_bpf_only-v2-2-c76e5250ea1c@arm.com Signed-off-by: Alexei Starovoitov <ast@kernel.org> 
Prepare for future changes where EXTRA_CFLAGS may include flags not
applicable to the host compiler.

Move the HOST_CFLAGS assignment before appending EXTRA_CFLAGS to
CFLAGS so that HOST_CFLAGS does not inherit flags from EXTRA_CFLAGS.

Acked-by: Quentin Monnet <qmo@kernel.org>
Signed-off-by: Leo Yan <leo.yan@arm.com>
Link: https://lore.kernel.org/r/20260602-tools_build_fix_zero_init_bpf_only-v2-2-c76e5250ea1c@arm.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
bpftool: Pass host flags to bootstrap libbpf 2026-06-15T00:32:53+00:00 Leo Yan leo.yan@arm.com 2026-06-02T14:47:10+00:00 9080b97689dbf8d2c338a9af97cd2b4a714f25bf bpftool builds a bootstrap libbpf with HOSTCC, but the libbpf submake can still inherit target build flags through CFLAGS. This can break cross builds when host objects are compiled with target-only options. Since HOST_CFLAGS contains warning options that are not suitable for building libbpf, use LIBBPF_BOOTSTRAP_CFLAGS with the warning options removed to build the bootstrap libbpf. Clear EXTRA_CFLAGS so target extra flags are not mixed into the host bootstrap libbpf build. Signed-off-by: Leo Yan <leo.yan@arm.com> Acked-by: Quentin Monnet <qmo@kernel.org> Link: https://lore.kernel.org/r/20260602-tools_build_fix_zero_init_bpf_only-v2-1-c76e5250ea1c@arm.com Signed-off-by: Alexei Starovoitov <ast@kernel.org> 
bpftool builds a bootstrap libbpf with HOSTCC, but the libbpf submake can
still inherit target build flags through CFLAGS. This can break cross
builds when host objects are compiled with target-only options.

Since HOST_CFLAGS contains warning options that are not suitable for
building libbpf, use LIBBPF_BOOTSTRAP_CFLAGS with the warning options
removed to build the bootstrap libbpf. Clear EXTRA_CFLAGS so target
extra flags are not mixed into the host bootstrap libbpf build.

Signed-off-by: Leo Yan <leo.yan@arm.com>
Acked-by: Quentin Monnet <qmo@kernel.org>
Link: https://lore.kernel.org/r/20260602-tools_build_fix_zero_init_bpf_only-v2-1-c76e5250ea1c@arm.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
bpftool: Restrict feature tests during bootstrap compilation 2026-06-05T21:17:21+00:00 Ian Rogers irogers@google.com 2026-05-31T01:07:50+00:00 231fc9bc27fd03db171cab4e75116923250af7a7 When the perf build executes 'make -C ../bpf/bpftool bootstrap', bpftool's Makefile unconditionally evaluated feature checks for llvm, libcap, libbfd, and disassembler libraries because the bootstrap target was not exempted. Since the bootstrap bpftool strictly compiles minimal AST parsing and C code generation logic without linking LLVM or disassembler libraries, these feature check sub-makes are completely redundant. Exempt the bootstrap target from non-essential feature tests to eliminate unneeded sub-make fork overhead during Kbuild startup. Tested-by: James Clark <james.clark@linaro.org> Assisted-by: Gemini:gemini-3.1-pro-preview Signed-off-by: Ian Rogers <irogers@google.com> Acked-by: Quentin Monnet <qmo@kernel.org> Link: https://lore.kernel.org/r/20260531010750.525160-1-irogers@google.com Signed-off-by: Alexei Starovoitov <ast@kernel.org> 
When the perf build executes 'make -C ../bpf/bpftool bootstrap', bpftool's
Makefile unconditionally evaluated feature checks for llvm, libcap, libbfd,
and disassembler libraries because the bootstrap target was not exempted.

Since the bootstrap bpftool strictly compiles minimal AST parsing and C
code generation logic without linking LLVM or disassembler libraries, these
feature check sub-makes are completely redundant.

Exempt the bootstrap target from non-essential feature tests to eliminate
unneeded sub-make fork overhead during Kbuild startup.

Tested-by: James Clark <james.clark@linaro.org>
Assisted-by: Gemini:gemini-3.1-pro-preview
Signed-off-by: Ian Rogers <irogers@google.com>
Acked-by: Quentin Monnet <qmo@kernel.org>
Link: https://lore.kernel.org/r/20260531010750.525160-1-irogers@google.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
bpftool: Add rhash map documentation 2026-06-05T15:00:08+00:00 Mykyta Yatsenko yatsenko@meta.com 2026-06-05T11:41:28+00:00 2bea44ea3c4ef6cee3a7c8b6bd74ace093632bef Make bpftool documentation aware of the resizable hash map. Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com> Reviewed-by: Emil Tsalapatis <emil@etsalapatis.com> Link: https://lore.kernel.org/r/20260605-rhash-v7-11-5b8e05f8630d@meta.com Signed-off-by: Alexei Starovoitov <ast@kernel.org> 
Make bpftool documentation aware of the resizable hash map.

Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com>
Reviewed-by: Emil Tsalapatis <emil@etsalapatis.com>
Link: https://lore.kernel.org/r/20260605-rhash-v7-11-5b8e05f8630d@meta.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
bpftool: Use libbpf error code for flow dissector query 2026-06-03T22:30:23+00:00 Woojin Ji random6.xyz@gmail.com 2026-06-03T00:33:39+00:00 8a7f2bff2165e53595d1e91c160b340f978c0ab7 bpf_prog_query() returns a negative errno on failure. query_flow_dissector() currently closes the namespace fd and then reads errno to decide whether -EINVAL means that the running kernel does not support flow dissector queries. That errno check controls behavior, not just diagnostics: -EINVAL is handled as a non-fatal old-kernel case, while any other error makes bpftool net fail. The namespace fd is opened read-only, so close() is not expected to commonly fail in normal use. Still, the BPF_PROG_QUERY error is already available in err, and reading errno after an intervening close() is fragile. If close() does change errno, the compatibility branch may be based on close()'s error instead of the BPF_PROG_QUERY result. This was reproduced with an LD_PRELOAD fault injector that forced BPF_PROG_QUERY for BPF_FLOW_DISSECTOR to fail with EINVAL and then forced close() on the netns fd to fail with EIO. The unpatched bpftool reported "can't query prog: Input/output error". With this change, the same injected failure is handled as the intended non-fatal EINVAL compatibility case. Use the libbpf-returned error code instead. Keep the existing errno reset in the non-fatal path to preserve batch mode behavior. The success path is unchanged. Fixes: 7f0c57fec80f ("bpftool: show flow_dissector attachment status") Signed-off-by: Woojin Ji <random6.xyz@gmail.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Leon Hwang <leon.hwang@linux.dev> Acked-by: Yonghong Song <yonghong.song@linux.dev> Acked-by: Quentin Monnet <qmo@kernel.org> Link: https://lore.kernel.org/bpf/20260603003339.33791-1-random6.xyz@gmail.com Assisted-by: ChatGPT:gpt-5.5 
bpf_prog_query() returns a negative errno on failure.
query_flow_dissector() currently closes the namespace fd and then reads
errno to decide whether -EINVAL means that the running kernel does not
support flow dissector queries.

That errno check controls behavior, not just diagnostics: -EINVAL is
handled as a non-fatal old-kernel case, while any other error makes bpftool
net fail.

The namespace fd is opened read-only, so close() is not expected to
commonly fail in normal use. Still, the BPF_PROG_QUERY error is already
available in err, and reading errno after an intervening close() is
fragile. If close() does change errno, the compatibility branch may be
based on close()'s error instead of the BPF_PROG_QUERY result.

This was reproduced with an LD_PRELOAD fault injector that forced
BPF_PROG_QUERY for BPF_FLOW_DISSECTOR to fail with EINVAL and then
forced close() on the netns fd to fail with EIO. The unpatched bpftool
reported "can't query prog: Input/output error". With this change, the
same injected failure is handled as the intended non-fatal EINVAL
compatibility case.

Use the libbpf-returned error code instead. Keep the existing errno reset
in the non-fatal path to preserve batch mode behavior. The success path
is unchanged.

Fixes: 7f0c57fec80f ("bpftool: show flow_dissector attachment status")
Signed-off-by: Woojin Ji <random6.xyz@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Leon Hwang <leon.hwang@linux.dev>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Acked-by: Quentin Monnet <qmo@kernel.org>
Link: https://lore.kernel.org/bpf/20260603003339.33791-1-random6.xyz@gmail.com

Assisted-by: ChatGPT:gpt-5.5
bpftool: Fix typo in struct_ops map FD generation for light skeleton 2026-05-28T21:19:15+00:00 Siddharth Nayyar sidnayyar@google.com 2026-05-20T09:40:44+00:00 be4c6c7bc42952b71188894933946b410deadcfe When generating light skeletons for BPF programs containing struct_ops maps, bpftool incorrectly outputs a stray literal 't' instead of a tab character for the map file descriptor member in the links structure. This causes a compilation error when the generated light skeleton is used. Correct the format string by replacing 't' with '\t'. Fixes: 08ac454e258e ("libbpf: Auto-attach struct_ops BPF maps in BPF skeleton") Signed-off-by: Siddharth Nayyar <sidnayyar@google.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Quentin Monnet <qmo@kernel.org> Link: https://lore.kernel.org/bpf/20260520-struct_ops_gen_typo_fix-v1-1-4dee3771da46@google.com 
When generating light skeletons for BPF programs containing struct_ops
maps, bpftool incorrectly outputs a stray literal 't' instead of a tab
character for the map file descriptor member in the links structure.
This causes a compilation error when the generated light skeleton is
used.

Correct the format string by replacing 't' with '\t'.

Fixes: 08ac454e258e ("libbpf: Auto-attach struct_ops BPF maps in BPF skeleton")
Signed-off-by: Siddharth Nayyar <sidnayyar@google.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Quentin Monnet <qmo@kernel.org>
Link: https://lore.kernel.org/bpf/20260520-struct_ops_gen_typo_fix-v1-1-4dee3771da46@google.com
bpftool: Support 24-bit vlen 2026-04-21T00:52:48+00:00 Alan Maguire alan.maguire@oracle.com 2026-04-17T14:30:20+00:00 22b402457ee40f64ea220f4b60776a612f084636 Adjust btf_vlen() usage to handle 24-bit vlen. Signed-off-by: Alan Maguire <alan.maguire@oracle.com> Link: https://lore.kernel.org/r/20260417143023.1551481-4-alan.maguire@oracle.com Signed-off-by: Alexei Starovoitov <ast@kernel.org> 
Adjust btf_vlen() usage to handle 24-bit vlen.

Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
Link: https://lore.kernel.org/r/20260417143023.1551481-4-alan.maguire@oracle.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>