kernel.git/tools/lib/bpf/btf.c, branch linux-5.10.y

libbpf: Fix btf__align_of() by taking into account field offsets

2023-03-11T15:39:17Z

[ Upstream commit 25a4481b4136af7794e1df2d6c90ed2f354d60ce ] btf__align_of() is supposed to be return alignment requirement of a requested BTF type. For STRUCT/UNION it doesn't always return correct value, because it calculates alignment only based on field types. But for packed structs this is not enough, we need to also check field offsets and struct size. If field offset isn't aligned according to field type's natural alignment, then struct must be packed. Similarly, if struct size is not a multiple of struct's natural alignment, then struct must be packed as well. This patch fixes this issue precisely by additionally checking these conditions. Fixes: 3d208f4ca111 ("libbpf: Expose btf__align_of() API") Signed-off-by: Andrii Nakryiko Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20221212211505.558851-5-andrii@kernel.org Signed-off-by: Sasha Levin

libbpf: Fix BTF header parsing checks

2021-11-18T13:04:10Z

[ Upstream commit c825f5fee19caf301d9821cd79abaa734322de26 ] Original code assumed fixed and correct BTF header length. That's not always the case, though, so fix this bug with a proper additional check. And use actual header length instead of sizeof(struct btf_header) in sanity checks. Fixes: 8a138aed4a80 ("bpf: btf: Add BTF support to libbpf") Reported-by: Evgeny Vereshchagin Signed-off-by: Andrii Nakryiko Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20211023003157.726961-2-andrii@kernel.org Signed-off-by: Sasha Levin

libbpf: Fix overflow in BTF sanity checks

2021-11-18T13:04:10Z

[ Upstream commit 5245dafe3d49efba4d3285cf27ee1cc1eeafafc6 ] btf_header's str_off+str_len or type_off+type_len can overflow as they are u32s. This will lead to bypassing the sanity checks during BTF parsing, resulting in crashes afterwards. Fix by using 64-bit signed integers for comparison. Fixes: d8123624506c ("libbpf: Fix BTF data layout checks and allow empty BTF") Reported-by: Evgeny Vereshchagin Signed-off-by: Andrii Nakryiko Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20211023003157.726961-1-andrii@kernel.org Signed-off-by: Sasha Levin

libbpf: Allow loading empty BTFs

2021-11-18T13:04:10Z

[ Upstream commit b8d52264df85ec12f370c0a8b28d0ac59a05877a ] Empty BTFs do come up (e.g., simple kernel modules with no new types and strings, compared to the vmlinux BTF) and there is nothing technically wrong with them. So remove unnecessary check preventing loading empty BTFs. Fixes: d8123624506c ("libbpf: Fix BTF data layout checks and allow empty BTF") Reported-by: Christopher William Snowhill Signed-off-by: Andrii Nakryiko Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20210110070341.1380086-2-andrii@kernel.org Signed-off-by: Sasha Levin

libbpf: Fix BTF data layout checks and allow empty BTF

2021-11-18T13:04:10Z

[ Upstream commit d8123624506cd62730c9cd9c7672c698e462703d ] Make data section layout checks stricter, disallowing overlap of types and strings data. Additionally, allow BTFs with no type data. There is nothing inherently wrong with having BTF with no types (put potentially with some strings). This could be a situation with kernel module BTFs, if module doesn't introduce any new type information. Also fix invalid offset alignment check for btf->hdr->type_off. Fixes: 8a138aed4a80 ("bpf: btf: Add BTF support to libbpf") Signed-off-by: Andrii Nakryiko Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20201105043402.2530976-8-andrii@kernel.org Signed-off-by: Sasha Levin

libbpf: Make btf_dump work with modifiable BTF

2020-09-30T19:30:22Z

Ensure that btf_dump can accommodate new BTF types being appended to BTF instance after struct btf_dump was created. This came up during attemp to use btf_dump for raw type dumping in selftests, but given changes are not excessive, it's good to not have any gotchas in API usage, so I decided to support such use case in general. Signed-off-by: Andrii Nakryiko Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20200929232843.1249318-2-andriin@fb.com

libbpf: Fix uninitialized variable in btf_parse_type_sec

2020-09-30T00:05:31Z

Fix obvious unitialized variable use that wasn't reported by compiler. libbpf Makefile changes to catch such errors are added separately. Fixes: 3289959b97ca ("libbpf: Support BTF loading and raw data output in both endianness") Signed-off-by: Andrii Nakryiko Signed-off-by: Alexei Starovoitov Acked-by: Martin KaFai Lau Link: https://lore.kernel.org/bpf/20200929220604.833631-1-andriin@fb.com

libbpf: Support BTF loading and raw data output in both endianness

2020-09-29T19:21:23Z

Teach BTF to recognized wrong endianness and transparently convert it internally to host endianness. Original endianness of BTF will be preserved and used during btf__get_raw_data() to convert resulting raw data to the same endianness and a source raw_data. This means that little-endian host can parse big-endian BTF with no issues, all the type data will be presented to the client application in native endianness, but when it's time for emitting BTF to persist it in a file (e.g., after BTF deduplication), original non-native endianness will be preserved and stored. It's possible to query original endianness of BTF data with new btf__endianness() API. It's also possible to override desired output endianness with btf__set_endianness(), so that if application needs to load, say, big-endian BTF and store it as little-endian BTF, it's possible to manually override this. If btf__set_endianness() was used to change endianness, btf__endianness() will reflect overridden endianness. Given there are no known use cases for supporting cross-endianness for .BTF.ext, loading .BTF.ext in non-native endianness is not supported. Signed-off-by: Andrii Nakryiko Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20200929043046.1324350-3-andriin@fb.com

selftests/bpf: Test BTF writing APIs

2020-09-29T02:17:13Z

Add selftests for BTF writer APIs. Signed-off-by: Andrii Nakryiko Signed-off-by: Alexei Starovoitov Acked-by: John Fastabend Link: https://lore.kernel.org/bpf/20200929020533.711288-4-andriin@fb.com

libbpf: Add btf__str_by_offset() as a more generic variant of name_by_offset

2020-09-29T02:17:13Z

BTF strings are used not just for names, they can be arbitrary strings used for CO-RE relocations, line/func infos, etc. Thus "name_by_offset" terminology is too specific and might be misleading. Instead, introduce btf__str_by_offset() API which uses generic string terminology. Signed-off-by: Andrii Nakryiko Signed-off-by: Alexei Starovoitov Acked-by: John Fastabend Link: https://lore.kernel.org/bpf/20200929020533.711288-3-andriin@fb.com