lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Fri, 10 May 2019 14:10:43 -0700 From: Andrii Nakryiko <andrii.nakryiko@...il.com> To: Alexei Starovoitov <alexei.starovoitov@...il.com> Cc: Andrii Nakryiko <andriin@...com>, Networking <netdev@...r.kernel.org>, Alexei Starovoitov <ast@...com>, Yonghong Song <yhs@...com>, Daniel Borkmann <daniel@...earbox.net> Subject: Re: [PATCH v2 bpf] libbpf: detect supported kernel BTF features and sanitize BTF On Fri, May 10, 2019 at 1:13 PM Alexei Starovoitov <alexei.starovoitov@...il.com> wrote: > > On Fri, May 10, 2019 at 11:41:50AM -0700, Andrii Nakryiko wrote: > > Depending on used versions of libbpf, Clang, and kernel, it's possible to > > have valid BPF object files with valid BTF information, that still won't > > load successfully due to Clang emitting newer BTF features (e.g., > > BTF_KIND_FUNC, .BTF.ext's line_info/func_info, BTF_KIND_DATASEC, etc), that > > are not yet supported by older kernel. > > > > This patch adds detection of BTF features and sanitizes BPF object's BTF > > by substituting various supported BTF kinds, which have compatible layout: > > - BTF_KIND_FUNC -> BTF_KIND_TYPEDEF > > - BTF_KIND_FUNC_PROTO -> BTF_KIND_ENUM > > - BTF_KIND_VAR -> BTF_KIND_INT > > - BTF_KIND_DATASEC -> BTF_KIND_STRUCT > > > > Replacement is done in such a way as to preserve as much information as > > possible (names, sizes, etc) where possible without violating kernel's > > validation rules. > > > > v1->v2: > > - add internal libbpf_util.h w/ common stuff > > - switch SK storage BTF to use new libbpf__probe_raw_btf() > > > > Reported-by: Alexei Starovoitov <ast@...com> > > Signed-off-by: Andrii Nakryiko <andriin@...com> > ... > > diff --git a/tools/lib/bpf/libbpf_util.h b/tools/lib/bpf/libbpf_util.h > > index da94c4cb2e4d..319e744eb33a 100644 > > --- a/tools/lib/bpf/libbpf_util.h > > +++ b/tools/lib/bpf/libbpf_util.h > > @@ -57,4 +57,16 @@ do { \ > > } /* extern "C" */ > > #endif > > > > +#define BTF_INFO_ENC(kind, kind_flag, vlen) \ > > + ((!!(kind_flag) << 31) | ((kind) << 24) | ((vlen) & BTF_MAX_VLEN)) > > +#define BTF_TYPE_ENC(name, info, size_or_type) (name), (info), (size_or_type) > > +#define BTF_INT_ENC(encoding, bits_offset, nr_bits) \ > > + ((encoding) << 24 | (bits_offset) << 16 | (nr_bits)) > > +#define BTF_TYPE_INT_ENC(name, encoding, bits_offset, bits, sz) \ > > + BTF_TYPE_ENC(name, BTF_INFO_ENC(BTF_KIND_INT, 0, 0), sz), \ > > + BTF_INT_ENC(encoding, bits_offset, bits) > > +#define BTF_MEMBER_ENC(name, type, bits_offset) (name), (type), (bits_offset) > > +#define BTF_PARAM_ENC(name, type) (name), (type) > > +#define BTF_VAR_SECINFO_ENC(type, offset, size) (type), (offset), (size) > > hmm. why are those needed in libbpf_util.h ? > I thought the goal is move them into libbpf_internal.h > and not to expose to users? Oh... Sorry, my bad, leftover from previous refactoring... Looks like there will be v3.
Powered by blists - more mailing lists