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2026-04-12bpftool: add missing fsession to the usage and docs of bpftoolMenglong Dong3-3/+3
Add the fsession attach type to the usage of bpftool in do_help(). Meanwhile, add it to the bash-completion and bpftool-prog.rst too. Acked-by: Leon Hwang <leon.hwang@linux.dev> Acked-by: Quentin Monnet <qmo@kernel.org> Signed-off-by: Menglong Dong <dongml2@chinatelecom.cn> Link: https://lore.kernel.org/r/20260412060346.142007-4-dongml2@chinatelecom.cn Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2026-03-29bpf: Support struct btf_struct_meta via KF_IMPLICIT_ARGSIhor Solodrai1-0/+1
The following kfuncs currently accept void *meta__ign argument: * bpf_obj_new_impl * bpf_obj_drop_impl * bpf_percpu_obj_new_impl * bpf_percpu_obj_drop_impl * bpf_refcount_acquire_impl * bpf_list_push_back_impl * bpf_list_push_front_impl * bpf_rbtree_add_impl The __ign suffix is an indicator for the verifier to skip the argument in check_kfunc_args(). Then, in fixup_kfunc_call() the verifier may set the value of this argument to struct btf_struct_meta * kptr_struct_meta from insn_aux_data. BPF programs must pass a dummy NULL value when calling these kfuncs. Additionally, the list and rbtree _impl kfuncs also accept an implicit u64 argument, which doesn't require __ign suffix because it's a scalar, and BPF programs explicitly pass 0. Add new kfuncs with KF_IMPLICIT_ARGS [1], that correspond to each _impl kfunc accepting meta__ign. The existing _impl kfuncs remain unchanged for backwards compatibility. To support this, add "btf_struct_meta" to the list of recognized implicit argument types in resolve_btfids. Implement is_kfunc_arg_implicit() in the verifier, that determines implicit args by inspecting both a non-_impl BTF prototype of the kfunc. Update the special_kfunc_list in the verifier and relevant checks to support both the old _impl and the new KF_IMPLICIT_ARGS variants of btf_struct_meta users. [1] https://lore.kernel.org/bpf/20260120222638.3976562-1-ihor.solodrai@linux.dev/ Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev> Acked-by: Jiri Olsa <jolsa@kernel.org> Link: https://lore.kernel.org/r/20260327203241.3365046-1-ihor.solodrai@linux.dev Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2026-03-24bpftool: Enable aarch64 ISA extensions for JIT disassemblyPuranjay Mohan1-1/+10
The LLVM disassembler needs ISA extension features enabled to correctly decode instructions from those extensions. On aarch64, without these features, instructions like LSE atomics (e.g. ldaddal) are silently decoded as incorrect instructions and disassembly is truncated. Use LLVMCreateDisasmCPUFeatures() with "+all" features for aarch64 targets so that the disassembler can handle any instruction the kernel JIT might emit. Before: int bench_trigger_uprobe(void * ctx): bpf_prog_538c6a43d1c6b84c_bench_trigger_uprobe: ; int cpu = bpf_get_smp_processor_id(); 0: mov x9, x30 4: nop 8: stp x29, x30, [sp, #-16]! c: mov x29, sp 10: stp xzr, x26, [sp, #-16]! 14: mov x26, sp 18: mrs x10, SP_EL0 1c: ldr w7, [x10, #16] ; __sync_add_and_fetch(&hits[cpu & CPU_MASK].value, 1); 20: and w7, w7, #0xff ; __sync_add_and_fetch(&hits[cpu & CPU_MASK].value, 1); 24: lsl x7, x7, #7 28: mov x0, #-281474976710656 2c: movk x0, #32768, lsl #32 30: movk x0, #35407, lsl #16 34: add x0, x0, x7 38: mov x1, #1 ; __sync_add_and_fetch(&hits[cpu & CPU_MASK].value, 1); 3c: mov x1, #1 After: int bench_trigger_uprobe(void * ctx): bpf_prog_538c6a43d1c6b84c_bench_trigger_uprobe: ; int cpu = bpf_get_smp_processor_id(); 0: mov x9, x30 4: nop 8: stp x29, x30, [sp, #-16]! c: mov x29, sp 10: stp xzr, x26, [sp, #-16]! 14: mov x26, sp 18: mrs x10, SP_EL0 1c: ldr w7, [x10, #16] ; __sync_add_and_fetch(&hits[cpu & CPU_MASK].value, 1); 20: and w7, w7, #0xff ; __sync_add_and_fetch(&hits[cpu & CPU_MASK].value, 1); 24: lsl x7, x7, #7 28: mov x0, #-281474976710656 2c: movk x0, #32768, lsl #32 30: movk x0, #35407, lsl #16 34: add x0, x0, x7 38: mov x1, #1 ; __sync_add_and_fetch(&hits[cpu & CPU_MASK].value, 1); 3c: ldaddal x1, x1, [x0] ; return 0; 40: mov w7, #0 44: ldp xzr, x26, [sp], #16 48: ldp x29, x30, [sp], #16 4c: mov x0, x7 50: ret 54: nop 58: ldr x10, #8 5c: br x10 Signed-off-by: Puranjay Mohan <puranjay@kernel.org> Acked-by: Yonghong Song <yonghong.song@linux.dev> Acked-by: Leon Hwang <leon.hwang@linux.dev> Acked-by: Quentin Monnet <qmo@kernel.org> Reviewed-by: Emil Tsalapatis <emil@etsalapatis.com> Link: https://lore.kernel.org/r/20260318172259.2882792-1-puranjay@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2026-03-17bpftool: Allow explicitly skip llvm, libbfd and libcrypto dependenciesMykyta Yatsenko3-4/+47
Introduce SKIP_LLVM, SKIP_LIBBFD, and SKIP_CRYPTO build flags that let users build bpftool without these optional dependencies. SKIP_LLVM=1 skips LLVM even when detected. SKIP_LIBBFD=1 prevents the libbfd JIT disassembly fallback when LLVM is absent. Together, they produce a bpftool with no disassembly support. SKIP_CRYPTO=1 excludes sign.c and removes the -lcrypto link dependency. Inline stubs in main.h return errors with a clear message if signing functions are called at runtime. Use BPFTOOL_WITHOUT_CRYPTO (not HAVE_LIBCRYPTO_SUPPORT) as the C define, following the BPFTOOL_WITHOUT_SKELETONS naming convention for bpftool-internal build config, leaving HAVE_LIBCRYPTO_SUPPORT free for proper feature detection in the future. All three flags are propagated through the selftests Makefile to bpftool sub-builds. Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20260312-b4-bpftool_build-v2-1-4c9d57133644@meta.com
2026-03-09Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf 7.0-rc3Alexei Starovoitov1-2/+7
Cross-merge BPF and other fixes after downstream PR. No conflicts. Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2026-03-07resolve_btfids: Fix linker flags detectionIhor Solodrai1-2/+7
The "|| echo -lzstd" default makes zstd an unconditional link dependency of resolve_btfids. On systems where libzstd-dev is not installed and pkg-config fails, the linker fails: ld: cannot find -lzstd: No such file or directory libzstd is a transitive dependency of libelf, so the -lzstd flag is strictly necessary only for static builds [1]. Remove ZSTD_LIBS variable, and instead set LIBELF_LIBS depending on whether the build is static or not. Use $(HOSTPKG_CONFIG) as primary source of the flags list. Also add a default value for HOSTPKG_CONFIG in case it's not built via the toplevel Makefile. Pass it from selftests/bpf too. [1] https://lore.kernel.org/bpf/4ff82800-2daa-4b9f-95a9-6f512859ee70@linux.dev/ Reported-by: BPF CI Bot (Claude Opus 4.6) <bot+bpf-ci@kernel.org> Reported-by: Vitaly Chikunov <vt@altlinux.org> Closes: https://lore.kernel.org/bpf/aaWqMcK-2AQw5dx8@altlinux.org/ Fixes: 4021848a903e ("selftests/bpf: Pass through build flags to bpftool and resolve_btfids") Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev> Reviewed-by: Paul Chaignon <paul.chaignon@gmail.com> Link: https://lore.kernel.org/r/20260305014730.3123382-1-ihor.solodrai@linux.dev Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2026-03-06bpftool: Support merging multiple module BTFs in btf dumpJosef Bacik3-17/+121
Add support for specifying multiple file sources in 'bpftool btf dump' to generate a single C header containing types from vmlinux plus multiple kernel modules: bpftool btf dump file /sys/kernel/btf/mod1 file /sys/kernel/btf/mod2 format c This is useful for BPF programs that need to access types defined in kernel modules. Previously this required a separate bpftool invocation for each module, producing separate headers that could not be combined due to overlapping vmlinux type definitions. The implementation collects all file paths, then for the multi-file case creates an empty split BTF on the vmlinux base and iteratively merges each module's types into it via btf__add_btf(). The single-file code path is preserved exactly to avoid any regression risk. Auto-detection of vmlinux as the base BTF from sysfs paths works as before. If vmlinux itself appears in the file list it is skipped with a warning since its types are already provided by the base. Assisted-by: Claude:claude-opus-4-6 Signed-off-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Reviewed-by: Alan Maguire <alan.maguire@oracle.com> Link: https://lore.kernel.org/bpf/b19c2760ffe48cec546dd3810d237f8cad20d606.1772657690.git.josef@toxicpanda.com
2026-02-24resolve_btfids: Fix memory leaks reported by ASANIhor Solodrai1-27/+54
Running resolve_btfids with ASAN reveals memory leaks in btf_id handling. - Change get_id() to use a local buffer - Make btf_id__add() strdup the name internally - Add btf_id__free_all() that frees all nodese of a tree - Call the cleanup function on exit for every tree Acked-by: Jiri Olsa <jolsa@kernel.org> Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev> Link: https://lore.kernel.org/r/20260223190736.649171-8-ihor.solodrai@linux.dev Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2026-02-24selftests/bpf: Pass through build flags to bpftool and resolve_btfidsIhor Solodrai1-2/+5
EXTRA_* and SAN_* build flags were not correctly propagated to bpftool and resolve_btids when building selftests/bpf. This led to various build errors on attempt to build with SAN_CFLAGS="-fsanitize=address", for example. Fix the makefiles to address this: - Pass SAN_CFLAGS/SAN_LDFLAGS to bpftool and resolve_btfids build - Propagate EXTRA_LDFLAGS to resolve_btfids link command - Use pkg-config to detect zlib and zstd for resolve_btfids, similar libelf handling Also check for ASAN flag in selftests/bpf/Makefile for convenience. Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev> Link: https://lore.kernel.org/r/20260223190736.649171-7-ihor.solodrai@linux.dev Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2026-02-18bpftool: Fix truncated netlink dumpsJakub Kicinski1-1/+4
Netlink requires that the recv buffer used during dumps is at least min(PAGE_SIZE, 8k) (see the man page). Otherwise the messages will get truncated. Make sure bpftool follows this requirement, avoid missing information on systems with large pages. Acked-by: Quentin Monnet <qmo@kernel.org> Fixes: 7084566a236f ("tools/bpftool: Remove libbpf_internal.h usage in bpftool") Signed-off-by: Jakub Kicinski <kuba@kernel.org> Link: https://lore.kernel.org/r/20260217194150.734701-1-kuba@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2026-02-04resolve_btfids: Refactor the sort_btf_by_name functionDonglin Peng1-7/+11
Preserve original relative order of anonymous or same-named types to improve the consistency. No functional changes. Signed-off-by: Donglin Peng <pengdonglin@xiaomi.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20260202120114.3707141-1-dolinux.peng@gmail.com
2026-01-29bpftool: Fix dependencies for static buildIhor Solodrai1-2/+2
When building selftests/bpf with EXTRA_LDFLAGS=-static the follwoing error happens: LINK /ws/linux/tools/testing/selftests/bpf/tools/build/bpftool/bootstrap/bpftool /usr/bin/x86_64-linux-gnu-ld.bfd: /usr/lib/gcc/x86_64-linux-gnu/15/../../../x86_64-linux-gnu/libcrypto.a(libcrypto-lib-dso_dlfcn.o): in function `dlfcn_globallookup': [...] /usr/bin/x86_64-linux-gnu-ld.bfd: /usr/lib/gcc/x86_64-linux-gnu/15/../../../x86_64-linux-gnu/libcrypto.a(libcrypto-lib-c_zlib.o): in function `zlib_oneshot_expand_block': (.text+0xc64): undefined reference to `uncompress' /usr/bin/x86_64-linux-gnu-ld.bfd: /usr/lib/gcc/x86_64-linux-gnu/15/../../../x86_64-linux-gnu/libcrypto.a(libcrypto-lib-c_zlib.o): in function `zlib_oneshot_compress_block': (.text+0xce4): undefined reference to `compress' collect2: error: ld returned 1 exit status make[1]: *** [Makefile:252: /ws/linux/tools/testing/selftests/bpf/tools/build/bpftool/bootstrap/bpftool] Error 1 make: *** [Makefile:327: /ws/linux/tools/testing/selftests/bpf/tools/sbin/bpftool] Error 2 make: *** Waiting for unfinished jobs.... This is caused by wrong order of dependencies in the Makefile. Fix it. Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20260128211255.376933-1-ihor.solodrai@linux.dev
2026-01-25bpftool: add fsession supportMenglong Dong1-0/+1
Add BPF_TRACE_FSESSION to bpftool. Signed-off-by: Menglong Dong <dongml2@chinatelecom.cn> Link: https://lore.kernel.org/r/20260124062008.8657-10-dongml2@chinatelecom.cn Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2026-01-21resolve_btfids: Support for KF_IMPLICIT_ARGSIhor Solodrai1-0/+382
Implement BTF modifications in resolve_btfids to support BPF kernel functions with implicit arguments. For a kfunc marked with KF_IMPLICIT_ARGS flag, a new function prototype is added to BTF that does not have implicit arguments. The kfunc's prototype is then updated to a new one in BTF. This prototype is the intended interface for the BPF programs. A <func_name>_impl function is added to BTF to make the original kfunc prototype searchable for the BPF verifier. If a <func_name>_impl function already exists in BTF, its interpreted as a legacy case, and this step is skipped. Whether an argument is implicit is determined by its type: currently only `struct bpf_prog_aux *` is supported. As a result, the BTF associated with kfunc is changed from __bpf_kfunc bpf_foo(int arg1, struct bpf_prog_aux *aux); into bpf_foo_impl(int arg1, struct bpf_prog_aux *aux); __bpf_kfunc bpf_foo(int arg1); For more context see previous discussions and patches [1][2]. [1] https://lore.kernel.org/dwarves/ba1650aa-fafd-49a8-bea4-bdddee7c38c9@linux.dev/ [2] https://lore.kernel.org/bpf/20251029190113.3323406-1-ihor.solodrai@linux.dev/ Acked-by: Eduard Zingerman <eddyz87@gmail.com> Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev> Link: https://lore.kernel.org/r/20260120222638.3976562-6-ihor.solodrai@linux.dev Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2026-01-21resolve_btfids: Introduce finalize_btf() stepIhor Solodrai1-21/+48
Since recently [1][2] resolve_btfids executes final adjustments to the kernel/module BTF before it's embedded into the target binary. To keep the implementation simple, a clear and stable "pipeline" of how BTF data flows through resolve_btfids would be helpful. Some BTF modifications may change the ids of the types, so it is important to maintain correct order of operations with respect to .BTF_ids resolution too. This patch refactors the BTF handling to establish the following sequence: - load target ELF sections - load .BTF_ids symbols - this will be a dependency of btf2btf transformations in subsequent patches - load BTF and its base as is - (*) btf2btf transformations will happen here - finalize_btf(), introduced in this patch - does distill base and sort BTF - resolve and patch .BTF_ids This approach helps to avoid fixups in .BTF_ids data in case the ids change at any point of BTF processing, because symbol resolution happens on the finalized, ready to dump, BTF data. This also gives flexibility in BTF transformations, because they will happen on BTF that is not distilled and/or sorted yet, allowing to freely add, remove and modify BTF types. [1] https://lore.kernel.org/bpf/20251219181321.1283664-1-ihor.solodrai@linux.dev/ [2] https://lore.kernel.org/bpf/20260109130003.3313716-1-dolinux.peng@gmail.com/ Acked-by: Eduard Zingerman <eddyz87@gmail.com> Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev> Link: https://lore.kernel.org/r/20260120222638.3976562-5-ihor.solodrai@linux.dev Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2026-01-17bpftool: Add 'prepend' option for tcx attach to insert at chain startGyutae Bae3-12/+58
Add support for the 'prepend' option when attaching tcx_ingress and tcx_egress programs. This option allows inserting a BPF program at the beginning of the TCX chain instead of appending it at the end. The implementation uses BPF_F_BEFORE flag which automatically inserts the program at the beginning of the chain when no relative reference is specified. This change includes: - Modify do_attach_tcx() to support prepend insertion using BPF_F_BEFORE - Update documentation to describe the new 'prepend' option - Add bash completion support for the 'prepend' option on tcx attach types - Add example usage in the documentation - Add validation to reject 'overwrite' for non-XDP attach types The 'prepend' option is only valid for tcx_ingress and tcx_egress attach types. For XDP attach types, the existing 'overwrite' option remains available. Example usage: # bpftool net attach tcx_ingress name tc_prog dev lo prepend This feature is useful when the order of program execution in the TCX chain matters and users need to ensure certain programs run first. Co-developed-by: Siwan Kim <siwan.kim@navercorp.com> Signed-off-by: Siwan Kim <siwan.kim@navercorp.com> Signed-off-by: Gyutae Bae <gyutae.bae@navercorp.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Reviewed-by: Quentin Monnet <qmo@kernel.org> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20260112034516.22723-1-gyutae.opensource@navercorp.com
2026-01-14tools/resolve_btfids: Support BTF sorting featureDonglin Peng1-0/+64
This introduces a new BTF sorting phase that specifically sorts BTF types by name in ascending order, so that the binary search can be used to look up types. Signed-off-by: Donglin Peng <pengdonglin@xiaomi.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Eduard Zingerman <eddyz87@gmail.com> Link: https://lore.kernel.org/bpf/20260109130003.3313716-4-dolinux.peng@gmail.com
2026-01-09bpftool: Make skeleton C++ compatible with explicit castsWanLi Niu1-4/+4
Fix C++ compilation errors in generated skeleton by adding explicit pointer casts and use char * subtraction for offset calculation error: invalid conversion from 'void*' to '<obj_name>*' [-fpermissive] | skel = skel_alloc(sizeof(*skel)); | ~~~~~~~~~~^~~~~~~~~~~~~~~ | | | void* error: arithmetic on pointers to void | skel->ctx.sz = (void *)&skel->links - (void *)skel; | ~~~~~~~~~~~~~~~~~~~~ ^ ~~~~~~~~~~~~ error: assigning to 'struct <obj_name>__<ident> *' from incompatible type 'void *' | skel-><ident> = skel_prep_map_data((void *)data, 4096, | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | sizeof(data) - 1); | ~~~~~~~~~~~~~~~~~ error: assigning to 'struct <obj_name>__<ident> *' from incompatible type 'void *' | skel-><ident> = skel_finalize_map_data(&skel->maps.<ident>.initial_value, | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | 4096, PROT_READ | PROT_WRITE, skel->maps.<ident>.map_fd); | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Minimum reproducer: $ cat test.bpf.c int val; // placed in .bss section #include "vmlinux.h" #include <bpf/bpf_helpers.h> SEC("raw_tracepoint/sched_wakeup_new") int handle(void *ctx) { return 0; } $ cat test.cpp #include <cerrno> extern "C" { #include "test.bpf.skel.h" } $ bpftool btf dump file /sys/kernel/btf/vmlinux format c > vmlinux.h $ clang -g -O2 -target bpf -c test.bpf.c -o test.bpf.o $ bpftool gen skeleton test.bpf.o -L > test.bpf.skel.h $ g++ -c test.cpp -I. Co-developed-by: Menglong Dong <dongml2@chinatelecom.cn> Signed-off-by: WanLi Niu <niuwl1@chinatelecom.cn> Signed-off-by: Menglong Dong <dongml2@chinatelecom.cn> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20260106023123.2928-1-kiraskyler@163.com
2025-12-31resolve_btfids: Implement --patch_btfidsIhor Solodrai1-0/+117
Recent changes in BTF generation [1] rely on ${OBJCOPY} command to update .BTF_ids section data in target ELF files. This exposed a bug in llvm-objcopy --update-section code path, that may lead to corruption of a target ELF file. Specifically, because of the bug st_shndx of some symbols may be (incorrectly) set to 0xffff (SHN_XINDEX) [2][3]. While there is a pending fix for LLVM, it'll take some time before it lands (likely in 22.x). And the kernel build must keep working with older LLVM toolchains in the foreseeable future. Using GNU objcopy for .BTF_ids update would work, but it would require changes to LLVM-based build process, likely breaking existing build environments as discussed in [2]. To work around llvm-objcopy bug, implement --patch_btfids code path in resolve_btfids as a drop-in replacement for: ${OBJCOPY} --update-section .BTF_ids=${btf_ids} ${elf} Which works specifically for .BTF_ids section: ${RESOLVE_BTFIDS} --patch_btfids ${btf_ids} ${elf} This feature in resolve_btfids can be removed at some point in the future, when llvm-objcopy with a relevant bugfix becomes common. [1] https://lore.kernel.org/bpf/20251219181321.1283664-1-ihor.solodrai@linux.dev/ [2] https://lore.kernel.org/bpf/20251224005752.201911-1-ihor.solodrai@linux.dev/ [3] https://github.com/llvm/llvm-project/issues/168060#issuecomment-3533552952 Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev> Link: https://lore.kernel.org/r/20251231012558.1699758-1-ihor.solodrai@linux.dev Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2025-12-19resolve_btfids: Change in-place update with raw binary outputIhor Solodrai1-81/+143
Currently resolve_btfids updates .BTF_ids section of an ELF file in-place, based on the contents of provided BTF, usually within the same input file, and optionally a BTF base. Change resolve_btfids behavior to enable BTF transformations as part of its main operation. To achieve this, in-place ELF write in resolve_btfids is replaced with generation of the following binaries: * ${1}.BTF with .BTF section data * ${1}.BTF_ids with .BTF_ids section data if it existed in ${1} * ${1}.BTF.base with .BTF.base section data for out-of-tree modules The execution of resolve_btfids and consumption of its output is orchestrated by scripts/gen-btf.sh introduced in this patch. The motivation for emitting binary data is that it allows simplifying resolve_btfids implementation by delegating ELF update to the $OBJCOPY tool [1], which is already widely used across the codebase. There are two distinct paths for BTF generation and resolve_btfids application in the kernel build: for vmlinux and for kernel modules. For the vmlinux binary a .BTF section is added in a roundabout way to ensure correct linking. The patch doesn't change this approach, only the implementation is a little different. Before this patch it worked as follows: * pahole consumed .tmp_vmlinux1 [2] and added .BTF section with llvm-objcopy [3] to it * then everything except the .BTF section was stripped from .tmp_vmlinux1 into a .tmp_vmlinux1.bpf.o object [2], later linked into vmlinux * resolve_btfids was executed later on vmlinux.unstripped [4], updating it in-place After this patch gen-btf.sh implements the following: * pahole consumes .tmp_vmlinux1 and produces a *detached* file with raw BTF data * resolve_btfids consumes .tmp_vmlinux1 and detached BTF to produce (potentially modified) .BTF, and .BTF_ids sections data * a .tmp_vmlinux1.bpf.o object is then produced with objcopy copying BTF output of resolve_btfids * .BTF_ids data gets embedded into vmlinux.unstripped in link-vmlinux.sh by objcopy --update-section For kernel modules, creating a special .bpf.o file is not necessary, and so embedding of sections data produced by resolve_btfids is straightforward with objcopy. With this patch an ELF file becomes effectively read-only within resolve_btfids, which allows deleting elf_update() call and satellite code (like compressed_section_fix [5]). Endianness handling of .BTF_ids data is also changed. Previously the "flags" part of the section was bswapped in sets_patch() [6], and then Elf_Type was modified before elf_update() to signal to libelf that bswap may be necessary. With this patch we explicitly bswap entire data buffer on load and on dump. [1] https://lore.kernel.org/bpf/131b4190-9c49-4f79-a99d-c00fac97fa44@linux.dev/ [2] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/scripts/link-vmlinux.sh?h=v6.18#n110 [3] https://git.kernel.org/pub/scm/devel/pahole/pahole.git/tree/btf_encoder.c?h=v1.31#n1803 [4] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/scripts/link-vmlinux.sh?h=v6.18#n284 [5] https://lore.kernel.org/bpf/20200819092342.259004-1-jolsa@kernel.org/ [6] https://lore.kernel.org/bpf/cover.1707223196.git.vmalik@redhat.com/ Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Tested-by: Alan Maguire <alan.maguire@oracle.com> Acked-by: Eduard Zingerman <eddyz87@gmail.com> Link: https://lore.kernel.org/bpf/20251219181825.1289460-3-ihor.solodrai@linux.dev
2025-12-19resolve_btfids: Always build with -Wall -WerrorIhor Solodrai1-1/+2
resolve_btfids builds without compiler warnings currently, so let's enforce this for future changes with '-Wall -Werror' flags [1]. [1] https://lore.kernel.org/bpf/1957a60b-6c45-42a7-b525-a6e335a735ff@linux.dev/ Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Tested-by: Alan Maguire <alan.maguire@oracle.com> Link: https://lore.kernel.org/bpf/20251219181321.1283664-5-ihor.solodrai@linux.dev
2025-12-19resolve_btfids: Introduce enum btf_id_kindIhor Solodrai1-23/+60
Instead of using multiple flags, make struct btf_id tagged with an enum value indicating its kind in the context of resolve_btfids. Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Tested-by: Alan Maguire <alan.maguire@oracle.com> Acked-by: Eduard Zingerman <eddyz87@gmail.com> Link: https://lore.kernel.org/bpf/20251219181321.1283664-4-ihor.solodrai@linux.dev
2025-12-19resolve_btfids: Factor out load_btf()Ihor Solodrai1-13/+34
Increase the lifetime of parsed BTF in resolve_btfids by factoring load_btf() routine out of symbols_resolve() and storing the base_btf and btf pointers in the struct object. Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Tested-by: Alan Maguire <alan.maguire@oracle.com> Acked-by: Eduard Zingerman <eddyz87@gmail.com> Link: https://lore.kernel.org/bpf/20251219181321.1283664-3-ihor.solodrai@linux.dev
2025-12-19resolve_btfids: Rename object btf field to btf_pathIhor Solodrai1-5/+5
Rename the member of `struct object` holding the path to BTF data if provided via --btf arg. `btf_path` is less ambiguous. Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Tested-by: Alan Maguire <alan.maguire@oracle.com> Acked-by: Eduard Zingerman <eddyz87@gmail.com> Link: https://lore.kernel.org/bpf/20251219181321.1283664-2-ihor.solodrai@linux.dev
2025-12-10bpftool: Fix build warnings due to MS extensionsQuentin Monnet1-0/+2
The kernel is now built with -fms-extensions. Anonymous structs or unions permitted by these extensions have been used in several places, and can end up in the generated vmlinux.h file, for example: struct ns_tree { [...] }; [...] struct ns_common { [...] union { struct ns_tree; struct callback_head ns_rcu; }; }; Trying to include this header for compiling a tool may result in build warnings, if the compiler does not expect these extensions. This is the case, for example, with bpftool: In file included from skeleton/pid_iter.bpf.c:3: .../tools/testing/selftests/bpf/tools/build/bpftool/vmlinux.h:64057:3: warning: declaration does not declare anything [-Wmissing-declarations] 64057 | struct ns_tree; | ^~~~~~~~~~~~~~ Fix these build warnings in bpftool by turning on Microsoft extensions when compiling the two BPF programs that rely on vmlinux.h. Reported-by: Alexei Starovoitov <ast@kernel.org> Closes: https://lore.kernel.org/bpf/CAADnVQK9ZkPC7+R5VXKHVdtj8tumpMXm7BTp0u9CoiFLz_aPTg@mail.gmail.com/ Signed-off-by: Quentin Monnet <qmo@kernel.org> Link: https://lore.kernel.org/r/20251208130748.68371-1-qmo@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2025-11-29bpf: Remove runqslower toolHoyeon Lee6-393/+3
runqslower was added in commit 9c01546d26d2 "tools/bpf: Add runqslower tool to tools/bpf" as a BCC port to showcase early BPF CO-RE + libbpf workflows. runqslower continues to live in BCC (libbpf-tools), so there is no need to keep building and maintaining it. Drop tools/bpf/runqslower and remove all build hooks in tools/bpf and selftests accordingly. Signed-off-by: Hoyeon Lee <hoyeon.lee@suse.com> Link: https://lore.kernel.org/r/20251126093821.373291-1-hoyeon.lee@suse.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2025-11-24bpftool: Allow bpftool to build with openssl < 3Alan Maguire1-0/+6
ERR_get_error_all()[1] is a openssl v3 API, so to make code compatible with openssl v1 utilize ERR_get_err_line_data instead. Since openssl is already a build requirement for the kernel (minimum requirement openssl 1.0.0), this will allow bpftool to compile where opensslv3 is not available. Signing-related BPF selftests pass with openssl v1. [1] https://docs.openssl.org/3.4/man3/ERR_get_error/ Fixes: 40863f4d6ef2 ("bpftool: Add support for signing BPF programs") Signed-off-by: Alan Maguire <alan.maguire@oracle.com> Acked-by: Song Liu <song@kernel.org> Acked-by: Quentin Monnet <qmo@kernel.org> Link: https://lore.kernel.org/r/20251120084754.640405-2-alan.maguire@oracle.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2025-11-15Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf after 6.18-rc5+Alexei Starovoitov1-1/+1
Cross-merge BPF and other fixes after downstream PR. Minor conflict in kernel/bpf/helpers.c Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2025-11-06bpftool: Recognize insn_array map typeAnton Protopopov2-2/+4
Teach bpftool to recognize instruction array map type. Signed-off-by: Anton Protopopov <a.s.protopopov@gmail.com> Acked-by: Quentin Monnet <qmo@kernel.org> Link: https://lore.kernel.org/r/20251105090410.1250500-3-a.s.protopopov@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2025-11-05bpf: add _impl suffix for bpf_stream_vprintk() kfuncMykyta Yatsenko1-1/+1
Rename bpf_stream_vprintk() to bpf_stream_vprintk_impl(). This makes bpf_stream_vprintk() follow the already established "_impl" suffix-based naming convention for kfuncs with the bpf_prog_aux argument provided by the verifier implicitly. This convention will be taken advantage of with the upcoming KF_IMPLICIT_ARGS feature to preserve backwards compatibility to BPF programs. Acked-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com> Link: https://lore.kernel.org/r/20251104-implv2-v3-2-4772b9ae0e06@meta.com Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Ihor Solodrai <ihor.solodrai@linux.dev>
2025-10-28bpftool: Fix missing closing parethesis for BTF_KIND_UNKNZhang Chujun1-1/+1
In the btf_dumper_do_type function, the debug print statement for BTF_KIND_UNKN was missing a closing parenthesis in the output format. This patch adds the missing ')' to ensure proper formatting of the dump output. Signed-off-by: Zhang Chujun <zhangchujun@cmss.chinamobile.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20251028063345.1911-1-zhangchujun@cmss.chinamobile.com
2025-09-27bpftool: Remove duplicate string.h headerJiapeng Chong1-1/+0
./tools/bpf/bpftool/sign.c: string.h is included more than once. Reported-by: Abaci Robot <abaci@linux.alibaba.com> Closes: https://bugzilla.openanolis.cn/show_bug.cgi?id=25502 Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com> Acked-by: Quentin Monnet <qmo@kernel.org> Link: https://lore.kernel.org/r/20250926095240.3397539-2-jiapeng.chong@linux.alibaba.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2025-09-23bpftool: Add bash completion for program signing optionsQuentin Monnet1-9/+17
Commit 40863f4d6ef2 ("bpftool: Add support for signing BPF programs") added new options for "bpftool prog load" and "bpftool gen skeleton". This commit brings the relevant update to the bash completion file. We rework slightly the processing of options to make completion more resilient for options that take an argument. Signed-off-by: Quentin Monnet <qmo@kernel.org> Link: https://lore.kernel.org/r/20250923103802.57695-1-qmo@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2025-09-23bpftool: Add support for signing BPF programsKP Singh9-11/+372
Two modes of operation being added: Add two modes of operation: * For prog load, allow signing a program immediately before loading. This is essential for command-line testing and administration. bpftool prog load -S -k <private_key> -i <identity_cert> fentry_test.bpf.o * For gen skeleton, embed a pre-generated signature into the C skeleton file. This supports the use of signed programs in compiled applications. bpftool gen skeleton -S -k <private_key> -i <identity_cert> fentry_test.bpf.o Generation of the loader program and its metadata map is implemented in libbpf (bpf_obj__gen_loader). bpftool generates a skeleton that loads the program and automates the required steps: freezing the map, creating an exclusive map, loading, and running. Users can use standard libbpf APIs directly or integrate loader program generation into their own toolchains. Signed-off-by: KP Singh <kpsingh@kernel.org> Acked-by: Quentin Monnet <qmo@kernel.org> Link: https://lore.kernel.org/r/20250921160120.9711-5-kpsingh@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2025-09-20bpftool: Fix -Wuninitialized-const-pointer warnings with clang >= 21Tom Stellard2-2/+2
This fixes the build with -Werror -Wall. btf_dumper.c:71:31: error: variable 'finfo' is uninitialized when passed as a const pointer argument here [-Werror,-Wuninitialized-const-pointer] 71 | info.func_info = ptr_to_u64(&finfo); | ^~~~~ prog.c:2294:31: error: variable 'func_info' is uninitialized when passed as a const pointer argument here [-Werror,-Wuninitialized-const-pointer] 2294 | info.func_info = ptr_to_u64(&func_info); | v2: - Initialize instead of using memset. Signed-off-by: Tom Stellard <tstellar@redhat.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Quentin Monnet <qmo@kernel.org> Link: https://lore.kernel.org/bpf/20250917183847.318163-1-tstellar@redhat.com
2025-09-20bpftool: Fix UAF in get_delegate_valueTao Chen1-53/+37
The return value ret pointer is pointing opts_copy, but opts_copy gets freed in get_delegate_value before return, fix this by free the mntent->mnt_opts strdup memory after show delegate value. Fixes: 2d812311c2b2 ("bpftool: Add bpf_token show") Signed-off-by: Tao Chen <chen.dylane@linux.dev> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Reviewed-by: Quentin Monnet <qmo@kernel.org> Link: https://lore.kernel.org/bpf/20250919034816.1287280-2-chen.dylane@linux.dev
2025-09-20bpftool: Add HELP_SPEC_OPTIONS in token.cTao Chen1-0/+1
$ ./bpftool token help Usage: bpftool token { show | list } bpftool token help OPTIONS := { {-j|--json} [{-p|--pretty}] | {-d|--debug} } Fixes: 2d812311c2b2 ("bpftool: Add bpf_token show") Signed-off-by: Tao Chen <chen.dylane@linux.dev> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Quentin Monnet <qmo@kernel.org> Link: https://lore.kernel.org/bpf/20250919034816.1287280-1-chen.dylane@linux.dev
2025-09-15bpftool: Search for tracefs at /sys/kernel/tracing firstQuentin Monnet1-9/+2
With "bpftool prog tracelog", bpftool prints messages from the trace pipe. To do so, it first needs to find the tracefs mount point to open the pipe. Bpftool looks at a few "default" locations, including /sys/kernel/debug/tracing and /sys/kernel/tracing. Some of these locations, namely /tracing and /trace, are not standard. They are in the list because some users used to hardcode the tracing directory to short names; but we have no compelling reason to look at these locations. If we fail to find the tracefs at the default locations, we have an additional step to find it by parsing /proc/mounts anyway, so it's safe to remove these entries from the list of default locations to check. Additionally, Alexei reports that looking for the tracefs at /sys/kernel/debug/tracing may automatically mount the file system under that location, and generate a kernel log message telling that auto-mounting there is deprecated. To avoid this message, let's swap the order for checking the potential mount points: try /sys/kernel/tracing first, which should be the standard location nowadays. The kernel log message may still appear if the tracefs is not mounted on /sys/kernel/tracing when we run bpftool. Reported-by: Alexei Starovoitov <ast@kernel.org> Closes: https://lore.kernel.org/r/CAADnVQLcMi5YQhZKsU4z3S2uVUAGu_62C33G2Zx_ruG3uXa-Ug@mail.gmail.com/ Signed-off-by: Quentin Monnet <qmo@kernel.org> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/r/20250915134209.36568-1-qmo@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2025-09-02bpftool: Add CET-aware symbol matching for x86_64 architecturesYuan Chen1-4/+50
Adjust symbol matching logic to account for Control-flow Enforcement Technology (CET) on x86_64 systems. CET prefixes functions with a 4-byte 'endbr' instruction, shifting the actual hook entry point to symbol + 4. Signed-off-by: Yuan Chen <chenyuan@kylinos.cn> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Quentin Monnet <qmo@kernel.org> Acked-by: Yonghong Song <yonghong.song@linux.dev> Acked-by: Jiri Olsa <jolsa@kernel.org> Link: https://lore.kernel.org/bpf/20250829061107.23905-3-chenyuan_fl@163.com
2025-09-02bpftool: Refactor kernel config reading into common helperYuan Chen3-82/+106
Extract the kernel configuration file parsing logic from feature.c into a new read_kernel_config() function in common.c. This includes: 1. Moving the config file handling and option parsing code 2. Adding required headers and struct definition 3. Keeping all existing functionality The refactoring enables sharing this logic with other components while maintaining current behavior. This will be used by subsequent patches that need to check kernel config options. Signed-off-by: Yuan Chen <chenyuan@kylinos.cn> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Quentin Monnet <qmo@kernel.org> Acked-by: Yonghong Song <yonghong.song@linux.dev> Acked-by: Jiri Olsa <jolsa@kernel.org> Link: https://lore.kernel.org/bpf/20250829061107.23905-2-chenyuan_fl@163.com
2025-08-19bpftool: Add kernel.kptr_restrict hint for no instructionsVincent Li1-1/+1
From bpftool's github repository issue [0]: When a Linux distribution has the kernel.kptr_restrict set to 2, bpftool prog dump jited returns "no instructions returned". This message can be puzzling to bpftool users who are not familiar with kernel BPF internals, so add a small hint for bpftool users to check the kernel.kptr_restrict setting similar to the DUMP_XLATED case. Outside of kernel.kptr_restrict, no instructions could also be returned in case the JIT was disabled. Signed-off-by: Vincent Li <vincent.mc.li@gmail.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://github.com/libbpf/bpftool/issues/184 [0] Link: https://lore.kernel.org/bpf/20250818165113.15982-1-vincent.mc.li@gmail.com
2025-08-02bpftool: Add bash completion for token argumentTao Chen1-0/+11
This commit updates the bash completion script with the new token argument. $ bpftool token help list show Reviewed-by: Quentin Monnet <qmo@kernel.org> Signed-off-by: Tao Chen <chen.dylane@linux.dev> Link: https://lore.kernel.org/r/20250723144442.1427943-3-chen.dylane@linux.dev Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2025-08-02bpftool: Add bpftool-token manpageTao Chen1-0/+64
Add bpftool-token manpage with information and examples of token-related commands. Suggested-by: Quentin Monnet <qmo@kernel.org> Reviewed-by: Quentin Monnet <qmo@kernel.org> Signed-off-by: Tao Chen <chen.dylane@linux.dev> Link: https://lore.kernel.org/r/20250723144442.1427943-2-chen.dylane@linux.dev Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2025-08-02bpftool: Add bpf_token showTao Chen3-1/+228
Add `bpftool token show` command to get token info from bpffs in /proc/mounts. Example plain output for `token show`: token_info /sys/fs/bpf/token allowed_cmds: map_create prog_load allowed_maps: allowed_progs: kprobe allowed_attachs: xdp token_info /sys/fs/bpf/token2 allowed_cmds: map_create prog_load allowed_maps: allowed_progs: kprobe allowed_attachs: xdp Example json output for `token show`: [{ "token_info": "/sys/fs/bpf/token", "allowed_cmds": ["map_create", "prog_load"], "allowed_maps": [], "allowed_progs": ["kprobe"], "allowed_attachs": ["xdp"] }, { "token_info": "/sys/fs/bpf/token2", "allowed_cmds": ["map_create", "prog_load"], "allowed_maps": [], "allowed_progs": ["kprobe"], "allowed_attachs": ["xdp"] }] Reviewed-by: Quentin Monnet <qmo@kernel.org> Signed-off-by: Tao Chen <chen.dylane@linux.dev> Link: https://lore.kernel.org/r/20250723144442.1427943-1-chen.dylane@linux.dev Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2025-07-04bpftool: Add support for dumping streamsKumar Kartikeya Dwivedi3-2/+70
Add support for printing the BPF stream contents of a program in bpftool. The new bpftool prog tracelog command is extended to take stdout and stderr arguments, and then the prog specification. The bpf_prog_stream_read() API added in previous patch is simply reused to grab data and then it is dumped to the respective file. The stdout data is sent to stdout, and stderr is printed to stderr. Cc: Quentin Monnet <qmo@kernel.org> Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com> Link: https://lore.kernel.org/r/20250703204818.925464-12-memxor@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2025-06-26Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf after rc3Alexei Starovoitov1-1/+1
Cross-merge BPF, perf and other fixes after downstream PRs. It restores BPF CI to green after critical fix commit bc4394e5e79c ("perf: Fix the throttle error of some clock events") No conflicts. Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2025-06-20bpftool: Fix memory leak in dump_xx_nlmsg on realloc failureYuan Chen1-6/+9
In function dump_xx_nlmsg(), when realloc() fails to allocate memory, the original pointer to the buffer is overwritten with NULL. This causes a memory leak because the previously allocated buffer becomes unreachable without being freed. Fixes: 7900efc19214 ("tools/bpf: bpftool: improve output format for bpftool net") Signed-off-by: Yuan Chen <chenyuan@kylinos.cn> Reviewed-by: Quentin Monnet <qmo@kernel.org> Link: https://lore.kernel.org/r/20250620012133.14819-1-chenyuan_fl@163.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2025-06-20bpftool: Use appropriate permissions for map accessSlava Imameev8-51/+96
Modify several functions in tools/bpf/bpftool/common.c to allow specification of requested access for file descriptors, such as read-only access. Update bpftool to request only read access for maps when write access is not required. This fixes errors when reading from maps that are protected from modification via security_bpf_map. Signed-off-by: Slava Imameev <slava.imameev@crowdstrike.com> Reviewed-by: Quentin Monnet <qmo@kernel.org> Link: https://lore.kernel.org/r/20250620151812.13952-1-slava.imameev@crowdstrike.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2025-06-17bpftool: Fix JSON writer resource leak in version commandYuan Chen1-3/+3
When using `bpftool --version -j/-p`, the JSON writer object created in do_version() was not properly destroyed after use. This caused a memory leak each time the version command was executed with JSON output. Fix: 004b45c0e51a (tools: bpftool: provide JSON output for all possible commands) Suggested-by: Quentin Monnet <qmo@kernel.org> Signed-off-by: Yuan Chen <chenyuan@kylinos.cn> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Reviewed-by: Quentin Monnet <qmo@kernel.org> Link: https://lore.kernel.org/bpf/20250617132442.9998-1-chenyuan_fl@163.com
2025-06-13tools/bpf_jit_disasm: Fix potential negative tpath index in get_exec_path()Ruslan Semchenko1-0/+2
If readlink() fails, len will be -1, which can cause negative indexing and undefined behavior. This patch ensures that len is set to 0 on readlink failure, preventing such issues. Signed-off-by: Ruslan Semchenko <uncleruc2075@gmail.com> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/r/20250612131816.1870-1-uncleruc2075@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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