kernel.git/tools/bpf/bpftool/common.c, branch linux-6.1.y

bpftool: Fix readlink usage in get_fd_type

2025-06-04T12:40:17Z

[ Upstream commit 0053f7d39d491b6138d7c526876d13885cbb65f1 ] The `readlink(path, buf, sizeof(buf))` call reads at most sizeof(buf) bytes and *does not* append null-terminator to buf. With respect to that, fix two pieces in get_fd_type: 1. Change the truncation check to contain sizeof(buf) rather than sizeof(path). 2. Append null-terminator to buf. Reported by Coverity. Signed-off-by: Viktor Malik Signed-off-by: Andrii Nakryiko Reviewed-by: Quentin Monnet Link: https://lore.kernel.org/bpf/20250129071857.75182-1-vmalik@redhat.com Signed-off-by: Alexei Starovoitov Signed-off-by: Sasha Levin

bpftool: Un-const bpf_func_info to fix it for llvm 17 and newer

2024-08-03T06:49:03Z

[ Upstream commit f4aba3471cfb9ccf69b476463f19b4c50fef6b14 ] LLVM 17 started treating const structs as constants: * https://github.com/llvm/llvm-project/commit/0b2d5b967d98 Combined with pointer laundering via ptr_to_u64, which takes a const ptr, but in reality treats the underlying memory as mutable, this makes clang always pass zero to btf__type_by_id, which breaks full name resolution. Disassembly before (LLVM 16) and after (LLVM 17): - 8b 75 cc mov -0x34(%rbp),%esi - e8 47 8d 02 00 call 3f5b0 + 31 f6 xor %esi,%esi + e8 a9 8c 02 00 call 3f510 It's a bigger project to fix this properly (and a question whether LLVM itself should detect this), but for right now let's just fix bpftool. For more information, see this thread in bpf mailing list: * https://lore.kernel.org/bpf/CABWYdi0ymezpYsQsPv7qzpx2fWuTkoD1-wG1eT-9x-TSREFrQg@mail.gmail.com/T/ Fixes: b662000aff84 ("bpftool: Adding support for BTF program names") Signed-off-by: Ivan Babrou Signed-off-by: Andrii Nakryiko Acked-by: Nick Desaulniers Acked-by: Yonghong Song Link: https://lore.kernel.org/bpf/20240520225149.5517-1-ivan@cloudflare.com Signed-off-by: Sasha Levin

bpftool: Fix memory leak in do_build_table_cb

2022-12-31T12:32:23Z

[ Upstream commit fa55ef14ef4fe06198c0ce811b603aec24134bc2 ] strdup() allocates memory for path. We need to release the memory in the following error path. Add free() to avoid memory leak. Fixes: 8f184732b60b ("bpftool: Switch to libbpf's hashmap for pinned paths of BPF objects") Signed-off-by: Miaoqian Lin Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20221206071906.806384-1-linmq006@gmail.com Signed-off-by: Sasha Levin

bpftool: Fix NULL pointer dereference when pin {PROG, MAP, LINK} without FILE

2022-11-02T11:05:42Z

When using bpftool to pin {PROG, MAP, LINK} without FILE, segmentation fault will occur. The reson is that the lack of FILE will cause strlen to trigger NULL pointer dereference. The corresponding stacktrace is shown below: do_pin do_pin_any do_pin_fd mount_bpffs_for_pin strlen(name) <- NULL pointer dereference Fix it by adding validation to the common process. Fixes: 75a1e792c335 ("tools: bpftool: Allow all prog/map handles for pinning objects") Signed-off-by: Pu Lehui Signed-off-by: Daniel Borkmann Reviewed-by: Quentin Monnet Link: https://lore.kernel.org/bpf/20221102084034.3342995-1-pulehui@huaweicloud.com

bpftool: Remove BPF_OBJ_NAME_LEN restriction when looking up bpf program by name

2022-08-04T21:41:13Z

bpftool was limiting the length of names to BPF_OBJ_NAME_LEN in prog_parse fds. Since commit b662000aff84 ("bpftool: Adding support for BTF program names") we can get the full program name from BTF. This patch removes the restriction of name length when running `bpftool prog show name ${name}`. Test: Tested against some internal program names that were longer than `BPF_OBJ_NAME_LEN`, here a redacted example of what was ran to test. # previous behaviour $ sudo bpftool prog show name some_long_program_name Error: can't parse name # with the patch $ sudo ./bpftool prog show name some_long_program_name 123456789: tracing name some_long_program_name tag taghexa gpl .... ... ... ... # too long sudo ./bpftool prog show name $(python3 -c 'print("A"*128)') Error: can't parse name # not too long but no match $ sudo ./bpftool prog show name $(python3 -c 'print("A"*127)') Signed-off-by: Manu Bretelle Signed-off-by: Andrii Nakryiko Tested-by: Jiri Olsa Reviewed-by: Quentin Monnet Link: https://lore.kernel.org/bpf/20220801132409.4147849-1-chantr4@gmail.com

bpftool: Show also the name of type BPF_OBJ_LINK

2022-06-30T21:48:13Z

For example, /sys/fs/bpf/maps.debug is a BPF link. When you run `bpftool map show` to show it: Before: $ bpftool map show pinned /sys/fs/bpf/maps.debug Error: incorrect object type: unknown After: $ bpftool map show pinned /sys/fs/bpf/maps.debug Error: incorrect object type: link Signed-off-by: Yafang Shao Signed-off-by: Daniel Borkmann Reviewed-by: Quentin Monnet Link: https://lore.kernel.org/bpf/20220629154832.56986-5-laoar.shao@gmail.com

bpftool: Probe for memcg-based accounting before bumping rlimit

2022-06-29T21:33:02Z

Bpftool used to bump the memlock rlimit to make sure to be able to load BPF objects. After the kernel has switched to memcg-based memory accounting [0] in 5.11, bpftool has relied on libbpf to probe the system for memcg-based accounting support and for raising the rlimit if necessary [1]. But this was later reverted, because the probe would sometimes fail, resulting in bpftool not being able to load all required objects [2]. Here we add a more efficient probe, in bpftool itself. We first lower the rlimit to 0, then we attempt to load a BPF object (and finally reset the rlimit): if the load succeeds, then memcg-based memory accounting is supported. This approach was earlier proposed for the probe in libbpf itself [3], but given that the library may be used in multithreaded applications, the probe could have undesirable consequences if one thread attempts to lock kernel memory while memlock rlimit is at 0. Since bpftool is single-threaded and the rlimit is process-based, this is fine to do in bpftool itself. This probe was inspired by the similar one from the cilium/ebpf Go library [4]. [0] commit 97306be45fbe ("Merge branch 'switch to memcg-based memory accounting'") [1] commit a777e18f1bcd ("bpftool: Use libbpf 1.0 API mode instead of RLIMIT_MEMLOCK") [2] commit 6b4384ff1088 ("Revert "bpftool: Use libbpf 1.0 API mode instead of RLIMIT_MEMLOCK"") [3] https://lore.kernel.org/bpf/20220609143614.97837-1-quentin@isovalent.com/t/#u [4] https://github.com/cilium/ebpf/blob/v0.9.0/rlimit/rlimit.go#L39 Suggested-by: Daniel Borkmann Signed-off-by: Quentin Monnet Signed-off-by: Daniel Borkmann Reviewed-by: Stanislav Fomichev Acked-by: Yafang Shao Link: https://lore.kernel.org/bpf/20220629111351.47699-1-quentin@isovalent.com

Revert "bpftool: Use libbpf 1.0 API mode instead of RLIMIT_MEMLOCK"

2022-06-14T20:18:06Z

This reverts commit a777e18f1bcd32528ff5dfd10a6629b655b05eb8. In commit a777e18f1bcd ("bpftool: Use libbpf 1.0 API mode instead of RLIMIT_MEMLOCK"), we removed the rlimit bump in bpftool, because the kernel has switched to memcg-based memory accounting. Thanks to the LIBBPF_STRICT_AUTO_RLIMIT_MEMLOCK, we attempted to keep compatibility with other systems and ask libbpf to raise the limit for us if necessary. How do we know if memcg-based accounting is supported? There is a probe in libbpf to check this. But this probe currently relies on the availability of a given BPF helper, bpf_ktime_get_coarse_ns(), which landed in the same kernel version as the memory accounting change. This works in the generic case, but it may fail, for example, if the helper function has been backported to an older kernel. This has been observed for Google Cloud's Container-Optimized OS (COS), where the helper is available but rlimit is still in use. The probe succeeds, the rlimit is not raised, and probing features with bpftool, for example, fails. A patch was submitted [0] to update this probe in libbpf, based on what the cilium/ebpf Go library does [1]. It would lower the soft rlimit to 0, attempt to load a BPF object, and reset the rlimit. But it may induce some hard-to-debug flakiness if another process starts, or the current application is killed, while the rlimit is reduced, and the approach was discarded. As a workaround to ensure that the rlimit bump does not depend on the availability of a given helper, we restore the unconditional rlimit bump in bpftool for now. [0] https://lore.kernel.org/bpf/20220609143614.97837-1-quentin@isovalent.com/ [1] https://github.com/cilium/ebpf/blob/v0.9.0/rlimit/rlimit.go#L39 Signed-off-by: Quentin Monnet Signed-off-by: Daniel Borkmann Cc: Yafang Shao Cc: Stanislav Fomichev Link: https://lore.kernel.org/bpf/20220610112648.29695-2-quentin@isovalent.com

bpftool: Use libbpf_bpf_attach_type_str

2022-06-02T23:26:30Z

This change switches bpftool over to using the recently introduced libbpf_bpf_attach_type_str function instead of maintaining its own string representation for the bpf_attach_type enum. Note that contrary to other enum types, the variant names that bpftool maps bpf_attach_type to do not adhere a simple to follow rule. With bpf_prog_type, for example, the textual representation can easily be inferred by stripping the BPF_PROG_TYPE_ prefix and lowercasing the remaining string. bpf_attach_type violates this rule for various variants. We decided to fix up this deficiency with this change, meaning that bpftool uses the same textual representations as libbpf. Supporting tests, completion scripts, and man pages have been adjusted accordingly. However, we did add support for accepting (the now undocumented) original attach type names when they are provided by users. For the test (test_bpftool_synctypes.py), I have removed the enum representation checks, because we no longer mirror the various enum variant names in bpftool source code. For the man page, help text, and completion script checks we are now using enum definitions from uapi/linux/bpf.h as the source of truth directly. Signed-off-by: Daniel Müller Signed-off-by: Andrii Nakryiko Acked-by: Quentin Monnet Link: https://lore.kernel.org/bpf/20220523230428.3077108-10-deso@posteo.net

bpftool: Use libbpf 1.0 API mode instead of RLIMIT_MEMLOCK

2022-04-11T03:17:16Z

We have switched to memcg-based memory accouting and thus the rlimit is not needed any more. LIBBPF_STRICT_AUTO_RLIMIT_MEMLOCK was introduced in libbpf for backward compatibility, so we can use it instead now. libbpf_set_strict_mode always return 0, so we don't need to check whether the return value is 0 or not. Signed-off-by: Yafang Shao Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20220409125958.92629-4-laoar.shao@gmail.com